Question Bank for Power Coal Transportation Specialty 2

Thread Content

235. What are the different types of tensioning devices for belt conveyors, and what are their respective characteristics? Answer: There are three types of tensioning devices for belt conveyors: weight tensioners, screw tensioners, and automatic tensioners. Features: 1. The weight-hammer tensioning device can maintain uniform tension on the conveyor belt at all times ； 2. The screw tensioning device has the advantage of a short tensioning stroke, but it cannot automatically maintain a constant tension ； 3. The automatic tensioning device is quite excellent, as it can automatically apply even tension in response to changes in load. 236. What is screening? Answer: Screening is the process of using a sieve with holes to separate materials based on their particle size. Crushing is the process of using mechanical force to overcome and break the internal binding forces within materials, causing them to split from large pieces into smaller ones. 237. What is the function of the idler rollers in a belt conveyor? Answer: The function of idler rollers is to support the conveyor belt, reduce the resistance to its movement, and keep its sag within a certain limit, thereby ensuring smooth operation of the belt. 238. What is the function of the tensioning device in a belt conveyor? Answer: The tensioning device serves to ensure that the belt has sufficient tension, thereby creating the necessary friction between the drive drum and the belt. Another function of it is to control the sag of the belt between the supporting idlers, so as to allow the belt conveyor to operate properly. 239. What are the main components of an impeller coal feeder? Answer: The impeller coal feeder consists of a main drive mechanism and a crane drive mechanism. 1) The main drive system consists of a drive motor, a safety coupling, a reducer, cross-beam gears, bevel gear reducers, and impellers. 2) The traveling mechanism consists of a traveling motor, a reducer, gear couplings, wheel sleeve couplings, etc. 240. In how many stages is the material crushed by a ring coal crusher? Answer: The crushing process of a ring coal crusher can be divided into two stages. In the first stage, large pieces of coal are crushed by the impact force exerted by the coal crushing plates on the screen plate and the ring hammers ； In the second stage, the small coal pieces continue to be crushed on the screen under the rotation of the rotor and the continuous movement of the hammer rings; rolling, shearing, and grinding actions further take place to achieve the desired particle size, after which the particles are discharged through the gaps in the screen. 241. What are the basic principles for setting up interlocks between various equipment in the coal conveying system? Answer: In the event of a fault, all operating equipment from the fault point to the coal source must be automatically shut down. Except in cases where the coal crusher itself malfunctions, it may be excluded from the fault trip interlock mechanism. Under normal conditions, the equipment should be started in the opposite direction to the coal flow, and stopped in the direction of the coal flow. Under program control, the coal crusher can be started first and stopped last; otherwise, the proper operation of the coal conveying system cannot be ensured. 242. What are the main protective devices for motors? Answer: These mainly include inter-phase protection, single-phase ground fault protection, overload protection, and undervoltage protection, etc. 243. What information should the coal transfer duty officer report to the shift leader or the control room after conducting the handover inspection? Answer: It is necessary to report in a timely manner on the equipment’s operation during the previous shift, its maintenance and standby status, the cleanliness of the site, and the condition of the personnel on duty. 244. What are the reasons for the excessively large particle size of the output from a hammer mill, and what are the solutions? Answer: Reason: 1) There are broken parts in the holes of the sieve plate grid ； 2) Excessive gap between the hammer head and the sieve plate ； 3) Excessive wear of the hammer head and sieve plate. Treatment: 1) Replace the sieve plate ； 2) Adjust the gap ； 3) Replace the hammer head or sieve plate. What causes the impeller of the impeller coal feeder to get stuck? How to handle it? Answer: Reason: 1) The fastening screws of the impeller claws are loose ； 2) Severe deformation at the root of the impeller claws ； 3) There are large pieces of debris in the coal. Treatment: 1) Tighten screws ； 2) Replace the impeller claws ； 3) Remove large pieces of debris. 245. What are the causes of excessive bearing temperature in coal crushers and what are the solutions? Answer: Reason: 1) Damage to the bearing cage or lock sleeve ； 2) Grease contamination ； 3) The clearance of the rolling bearing is too small ； 4) Insufficient grease. Treatment: 1) Replace the bearing or lock sleeve ； 2) Clean the bearings ； 3) Replace the large clearance bearing ； 4) Fill with lubricating oil. 246. What are the “five simultaneities” that the State Council stipulates should be implemented in work related to work safety? Answer: When planning, arranging, checking, summarizing, and evaluating production, safety work is also planned, arranged, checked, summarized, and evaluated at the same time. 247. How to prevent electric shock accidents? Answer: 1) Strictly implement electrical safety regulations. 2) Earnestly carry out electrical safety education and publicity efforts. 3) Regularly check for violations and disciplinary issues, as well as the condition of electrical equipment. 248. What are the common causes of electric shock? Answer: 1) Improper installation of electrical wiring. 2) Insulation damage of electrical equipment. 3) Violation of safety operating procedures. 4) Lack of knowledge in electrical safety. 249. How to extinguish a fire in an electric motor? Answer: To extinguish a fire in an electric motor, it is necessary to first cut off the power supply to the motor before attempting to put out the fire. Dry chemical extinguishers, carbon dioxide extinguishers, or 1211 extinguishers should be used to put out the fire. 250. What should be done if someone is electrocuted? Answer: When someone is found to be electrocuted, the power supply should be cut off immediately to free the victim from the electric current, and first aid should be provided. When working at heights, care must be taken to prevent falls from great heights during rescue operations. 251. What is tape deviation? Answer: During the operation of a belt conveyor, sometimes the center line of the belt deviates from the center line of the conveyor and shifts to one side; this phenomenon is known as belt deviation. 252. What is automatic coal blending? Answer: By clicking “Program Allocation” on the upper-level computer in the control room, the coal spreader on the conveyor belt in the coal bin will distribute coal according to the level of coal in the bin – giving priority to situations with low coal levels, distributing coal in sequence as the level rises, and handling any remaining coal accordingly. 253. If it is found that the operating current of a certain device is abnormal, how should the programmed duty operator handle it? Answer: 1) During equipment operation, if the current reading suddenly increases or drops to zero, the inspector should be notified immediately to conduct a check; in emergency situations, the equipment operation should be stopped right away. 2) If the current indication of the conveyor belt changes frequently, the duty officer should be notified immediately to conduct an inspection and take appropriate action based on the specific situation. 3) The current of the belt at the next level is normal; however, the current of this belt conveyor is increasing gradually, which may be due to coal blockage. The duty operator should be notified immediately to conduct an inspection and take action, and the programmed control duty operator should immediately switch the industrial television to that equipment ； 4) If the current indication of the ring coal crusher changes frequently, the cause should be analyzed; if it is due to overload, the amount of coal fed should be reduced ； If coal clogs or it gets stuck by foreign objects, the machine should be stopped for handling ； In the event of an electrical fault, contact maintenance for repair. 5) During startup, if the motor current indication remains above the rated value for an extended period (usually not exceeding 5 seconds), the startup process should be stopped immediately; the cause should be analyzed and maintenance personnel should be notified to handle it. 254. What tasks should a programmed duty operator carry out before starting the equipment? Answer: 1) Follow the supervisor’s instructions to determine a suitable operating method, and promptly issue relevant orders to the various inspectors in order to carry out the inspections and preparations prior to system operation. 2) Check that the power connections for each component are correct, have good contact, and that the plugs are properly inserted. 3) Check that equipment in the programming room such as the CRT, programming main unit, UPS power supply, television monitors, and monitoring manipulators is in good condition. 4) Check whether the call system of the coal conveying system is in a reliable standby state. 5) Check whether all baffles in the system are consistent with the determined operating mode. 6) Check whether the telescoping device is in its normal working position. 7) Check that the signals from all auxiliary equipment and protection devices are normal. 255. What are the inspection items for belt conveyors during shift handover and operation? Answer: 1) The wiring and grounding of the motor and its electrical equipment must be in good condition. If the motor has been idle for a long time (especially those located in humid areas), it can only be used after electrical technicians verify that its insulation is satisfactory. 2) The oil levels in the reducer and hydraulic coupler are normal, and there is no oil leakage at any of the joint surfaces or shaft ends. 3) The foot screws of the motor and reducer, as well as the connection bolts of each drive drum, are all tightened properly with no signs of looseness. 4) The braking system is flexible and reliable, with no abnormal phenomena; all protective covers and guardrails are intact. 5) All tee baffles are intact and in the correct positions; the electric actuators operate properly, and the limit switches are undamaged. 6) The coal drop pipe is unobstructed, with no coal accumulation or leaks, and there are no debris on the coal grates. 7) All types of idlers are intact and operate smoothly. 8) The vibrator and coal chute clogging protection devices, as well as their electrical wiring, are in good condition, and the switches are in the correct position. 9) The drive drum and deflection drum are in good condition; there is no coal stuck to the drum walls, nor any damage. 10) The coal plows are in their raised position, and they operate in a flexible and reliable manner. 11) The belt shows no signs of scratches, tears, or delamination. 12) The bracket is not skewed. The idler frame is undamaged. 13) There are no foreign objects on or under the belt, and no jamming. 14) All types of sweepers are in good condition and in their correct positions. 15) The tensioning device is in good condition; the weight blocks are not displaced and are arranged neatly, with smooth tracks. 16) All various protective devices are in good condition. 17) The MCC and PC cabinets are in good condition; all indicator lights, switches, and buttons are intact and function reliably. 18) The sealing gasket of the material guide chute is in good condition, with no coal leakage. 19) All pier areas and transfer stations are well-lit, have sufficient light, and are kept clean. 20) The public address system and communication signal equipment along the coal transport system are in good condition and functioning properly. 21) The dust collectors and iron removers on each conveyor belt are in good condition and reliable, ready for operation. 22) The cutting edge of the coal plow is smooth, without any sharp burrs that could pose a threat to the safe operation of the belt; the plow moves up and down smoothly. 23) It is in place, and the protective devices are reliable. 24) The camera and its accessories are in good condition. 25) All expansion joint positions are correct, and the machine head locking device is in the locked position. 26) When there is water on Belt Conveyor #3, the wiper should be lowered. 256. What is the impact of changes in coal quality and type on boiler operation? Answer: 1) Volatile matter: Volatile matter is the primary indicator for determining the ignition characteristics of coal types. Different coal types have varying volatile matter contents; as the volatile matter content decreases, the ignition temperature of the coal powder rises significantly and its ignition speed slows down. Therefore, the ignition properties of coal depend primarily on its volatile matter content. The higher the volatile matter content, the lower the loss due to incomplete combustion of the ash. In general, the higher the volatile matter content, the faster the ignition speed and the lower the ignition temperature; as a result, the loss from incomplete combustion of the ash and the combustible content in the fly ash are reduced. Therefore, the volatile matter content of coal has a significant impact on the selection of boiler equipment design, the layout of heating surfaces, and the safe and economical operation of the boiler. Moisture: The moisture in coal is an inert substance. Its presence reduces the calorific value of coal; since coal used for power generation relies primarily on its heat content, during combustion the moisture in the coal absorbs heat, vaporizes, and becomes superheated. This not only diminishes the utilization of heat but also lowers the combustion temperature. When water vaporizes, its volume **increases**, which in turn raises the power consumption of the fan. An increase in the moisture content of coal leads to a gradual deterioration in its flowability, which can cause sticking and blockages in the coal discharge pipes, feeders, and coal hoppers of the coal transportation system ； An increase in the moisture content of coal also reduces the output of the coal grinder. Ash: The ash of coal is the residue that remains after combustion. As the ash content of coal increases and its combustible components decrease, its calorific value drops, resulting in an increased coal consumption at constant load. Coal with a high ash content delays the ignition time, reduces the combustion temperature, and as a result, reduces the combustion stability of the boiler. An increase in ash content reduces the degree of coal combustion, leading to increased losses due to incomplete combustion ； An increase in ash content leads to greater physical and thermal losses of the ash slag, which has a more significant impact on the economic efficiency of liquid slag discharge furnaces ； An increase in ash leads to more severe fouling and wear on the boiler’s heating surfaces. This fouling and coking severely affect heat transfer within the boiler, causing the exhaust temperature to rise and thereby reducing the boiler’s thermal efficiency. Moreover, increased wear on the heating surfaces shortens the boiler’s service life and poses a threat to its safe operation. The fusibility of ash also has a significant impact on boilers; coal with a high ash melting point can cause difficulties in slag removal in boilers that use liquid slag removal methods. Coal with a low ash melting point can cause coking in the furnace of boilers that use solid slag discharge, thereby hindering the continuous and safe operation of the boiler. 257. What is the impact of changes in coal quality and type on coal transportation systems? Answer: The quality and type of coal used in coal-fired power plants vary. These changes in coal type and quality have the following impacts on the coal transportation system: the impact of changes in calorific value on the coal transportation system. A decrease in the calorific value of coal leads to an increased consumption of coal, which raises the workload associated with coal transportation. The coal unloading equipment, storage facilities, screening and crushing equipment, as well as the coal conveyors may all be overburdened by the increased amount of coal, exceeding their designed capacity; this can disrupt production, place excessive strain on the coal transportation system, reduce the operational efficiency of the equipment, increase the frequency of failures, force a reduction in load, or even lead to the shutdown of the plant. 2) Impact of ash variation on the coal conveying system. Ash in coal is an unwanted component; its density is more than twice that of the combustible materials in coal. It increases the burden on transportation, and transporting the same volume of coal puts excessive strain on the coal transport equipment. Coal with a high ash content is hard in texture, difficult to crush, causes wear on equipment, and increases the maintenance workload for coal transportation equipment. The impact of moisture on the coal transport system; water in coal is also an unnecessary component. The higher the moisture content, the less organic matter there is accordingly. High moisture content during coal use reduces the efficiency of heat utilization and increases coal consumption. An increase in the moisture content in coal can cause coal to stick to and clog the coal conveying equipment; in severe cases, it can even halt the supply of coal, affecting production. When the moisture content in coal exceeds 10%, it will cause self-flowing, making it impossible for the coal feeding equipment to exert control and affecting production. In the harsh winter, coal with high moisture content will freeze, affecting coal unloading and loading. If the coal contains very little moisture, dust is generated in large amounts during unloading and loading, contaminating the environment. It affects both environmental hygiene and the health of employees. Volatiles and sulfur content have no significant impact on the coal transportation system. However, when using coal with high volatiles and high sulfur content, care must be taken in screening and grinding equipment to prevent explosions and spontaneous combustion. Because both the ignition point of volatile substances and that of sulfur are low, they tend to catch fire on their own. 258. What are the components of a hydraulic system? What is each one’s role? Answer: A complete hydraulic system consists of the following components: the power unit. Oil pump, used to convert mechanical energy into hydraulic energy. Operative part. Cylinders and hydraulic motors are used to convert hydraulic energy into mechanical energy. Control section. Pressure control valves, direction control valves, flow control valves, etc., are used to control and regulate fluid flow in order to meet the requirements for transmission performance. Working medium. Oil, used to transmit energy. Auxiliary part. Fuel tanks, oil filters, accumulators, heaters, coolers, pipelines, connectors, hydraulic gauges, etc. For hydraulic systems, some of these auxiliary components are essential, such as oil tanks, pipelines, and pipe fittings, while others are used to improve the quality of the transmission mechanism. 259. What is the purpose of the interlock on the coal conveyor belt? Answer: To ensure safe operation, all the equipment in the coal transportation system is started and stopped in a specific sequence according to certain operational requirements, with one device regulating the operation of another. The coal conveyor belt is one of the main devices that participate in interlocked operation in this way. When general equipment is started, it is activated one by one in the reverse order of the coal flow; whereas when it is shut down, it is stopped one by one in the same order as the coal flow. When a device involved in the interlock operation within the system fails and stops operating, the devices that come before it in the interlock sequence shut down automatically, while the devices that follow continue to operate. This helps to avoid or reduce the risk of coal accumulation and the escalation of accidents within the system. 260. What are the main reasons for severe coal leakage from the coal scraper? How to solve it? Answer: Reasons: 1) The plow blade is severely worn or clogged with debris ； 2) The plow blade is not straight or has poor contact with the belt surface ； 3) The plow head does not descend fully or is tilted ； 4) The guide angle at the rear of the plow blade is too large, or the scraper cannot be retracted ； 5) Severe damage to the belt surface ； 6) The horizontal idlers are uneven or the spacing between them is too large ； 7) The belt shifts toward the discharge side. Solution: 1) Replace the plow blade or remove debris ； 2) Corrective plowshare ； 3) Adjust the limit to correct the plow head ； 4) Reduce the guide angle or add additional closing scrapers ； 5) Replace the belt ； 6) Adjust or increase idler rollers ； 7) Offset adjustment. 261. What are the causes of belt breakage? How to handle it? Answer: Reasons: 1) Poor adhesion quality at the belt joints or severe wear, resulting in delamination or horizontal scratches ； 2) Belt too tight ； 3) High number of starts under load ； 4) Blockage of coal drop pipes and chutes ； 5) Severe coal accumulation at the head and tail sections, causing blockages ； 6) The tensioning device fails and gets stuck ； 7) The belt is operating under overload. Solution: 1) Stop operation immediately and re-adhere it ； 2) Appropriately reduce the counterweight ； 3) Avoid starting under load ； 4) Remove coal accumulation and blockages at the coal drop pipes and chutes ； 5) Remove coal accumulation at the head and tail to prevent blockages ； 6) Clear blockage ； 7) Reduce the transport volume. 262. What are the main aspects of motor operation monitoring? Answer: 1) Does the current exceed the allowable value? ； 2) Is the lubrication of the bearings proper? ； 3) Check whether the motor makes any abnormal noises, and there should be no burnt smell ； 4) Are the ambient temperature and motor temperature rise normal? ； 5) Are the enclosure grounding wires and cable terminal protective covers intact and secure? ； 6) Is the motor vibration normal? Are there any signs of sparking, smoking, dust accumulation, or water accumulation? ； 7) In the event of any abnormal phenomena, it should be reported promptly to the team leader or the electrical staff should be notified to conduct an inspection. 263. To prevent belt tearing, what aspects should be carefully checked before starting? Answer: Before starting the equipment, each inspector should conduct a thorough inspection in accordance with the operating procedures; only after confirming that there are no abnormalities can they notify the programmed duty officer to start the equipment ； Before starting up, it is necessary to carefully check whether the sweepers and coal scrapers are deformed, and whether there is any debris stuck inside the protective covers at the front end. It is also important to ensure that the primary and secondary blades of the wipers and coal scrapers are smooth without any burrs. Check whether the clamps used to hold the guide trough steel plates and the fixing angle irons are loose, and that the distance between the sealing strips and the belts is at least 5 cm. Verify that there are no hardware components or debris inside the drive rollers and the various direction-changing rollers. Also, check whether there is any debris on the belts in each circuit (especially those behind the empty-section sweepers). Ensure that none of the idler rollers have misaligned shafts or missing dust covers. Finally, check whether there is any debris stuck inside the guide troughs and coal discharge pipes. Any abnormalities found should be reported to the shift leader promptly so that appropriate action can be taken ； 264. To prevent belt tearing, what aspects should be carefully checked during operation? Answer: 1) While the equipment is in operation, the duty officer should closely monitor its operating conditions, the flow of coal, as well as any components that may fall off due to vibration. They should also keep an eye on the performance of the cleaners, and whether the disc and belt type iron removers are successfully removing iron particles. It is necessary to check whether there are any hard objects in the drive and tail rollers. If any signs of belt tearing are detected, the machine should be stopped immediately by pulling the emergency stop cord ； 2. During operation, it is strictly prohibited to operate the equipment beyond its capacity. If any abnormal objects or \"four large pieces\" are found on the belt, contact the programming operator promptly. In emergency situations, the emergency stop cable should be pulled immediately to shut down the machine ； 3. When a programmed duty officer receives a report of an abnormal situation from an inspector, they should closely monitor the operating status of the equipment at the relevant stations, and at the same time remind the duty officers at other related stations to pay attention ； The machine should be stopped immediately when an abnormality is detected ； 4. It is strictly prohibited to leave one’s post without permission, wander from one’s assigned area, leave the equipment under one’s supervision without authorization, or engage in any activities unrelated to work while on duty ； 5. In addition to strictly following the operational safety measures, the bucket wheel conveyor operator must also strictly implement the relevant safety measures to prevent belt tearing ； 6. After the belt starts operating, the programmed duty officer (deputy officer) must pay close attention to whether the direction of coal flow is correct. Once the coal supply equipment begins feeding coal, the monitor screen should be switched to show the coal bin area promptly, in order to prevent blockages in the coal discharge pipes ； 7. During operation, the programmed main and auxiliary operators must pay close attention to whether the current levels of various devices remain within normal ranges. If any abnormalities are detected, they should immediately contact the on-site operator for clarification; in emergency situations, the operation of the equipment must be stopped right away ； 8. Each shift shall conduct tests on the belt tear protection devices as required; any issues found should be recorded promptly as defects, and maintenance personnel should be contacted for handling ； 9. Each team should regularly inspect the steel plates used for alignment adjustment that are welded inside the coal discharge pipes. In the event that the belt suddenly deviates from its path or any other abnormal situation occurs, the machine should be stopped immediately for inspection, to prevent the steel plates from falling and causing scratches or tears in the belt ； 10. Strict monitoring should be exercised for equipment with serious defects (belts that are severely worn and scratched) ； 265. What preventive measures does the department take to avoid electric shock injuries and deaths? Answer: 1) Strictly implement the “two forms, three systems, and one form” system, and fill out the power outage and restoration notification forms in strict accordance with the regulations ； 2. When carrying out tasks related to operation tickets, strictly follow the procedures of \"reciting the instructions, repeating them, and then performing the operations\", as well as the supervisor system ； 3. When carrying out power outage and restoration tasks, it is necessary to follow the prescribed sequence of operations; it is strictly prohibited to perform such tasks without a supervisor present ； 4. When performing power outage and restoration operations, the operators and supervisors must wear clothing that complies with safety regulations, including insulating shoes, insulated gloves, and work uniforms ； 5. When performing power on/off operations or removing/installing fuses, it is strictly prohibited to use both hands, and it is also strictly prohibited for any other part of the body to come into contact with the control cabinet or the building ； 6 Move around randomly ； For 7 motors located in humid areas, it is necessary to first use a voltage tester to confirm that there are no abnormalities before checking their temperature and vibration levels ； 266. Measures to prevent electrical fires in coal conveying systems? Answer: 1) When dust accumulates in all cable trays (inside) of the system, defects should be recorded promptly and maintenance personnel should be contacted to handle it ； 2. When dust accumulates in all control cabinets and MCC cabinets of the system, defects should be recorded promptly and maintenance personnel should be contacted to handle it ； During use, if arcing is observed due to poor contact at the switches and contactor contacts, use should be stopped immediately, and maintenance personnel should be contacted for repairs ； Upon discovering arcing at the cable connections at the site, it is necessary to report to the team leader immediately and contact the relevant maintenance departments promptly for handling ； During operation, it is necessary to check the temperature rise of each motor regularly; if any abnormalities are detected, operation should be stopped immediately and maintenance personnel should be notified to handle the issue ； It is strictly prohibited to use copper wires, iron wires, or other metals that do not meet the requirements as substitutes for fuses, and it is also strictly prohibited to use fuses beyond their rated capacity ； 267. What are the measures to prevent track deviation accidents of the impeller coal feeder? Answer: 1) Inspectors should strictly follow the checks required before starting the impeller coal feeder as well as the precautions to be observed during its operation, as specified in the operating procedures ； 2. Before operation, check all protective devices of the impeller coal feeder to ensure their reliable operation ； 3. It is strictly prohibited for the duty officer to leave his post without permission during operation; what are the measures to prevent injuries caused by cleaning the roller screens and coal crushers? Answer: 1) When cleaning the coal crusher and coal screener, it is necessary to take all required safety measures before proceeding ； 4. When cleaning the coal accumulation and debris from coal crushers and screeners, safety measures must be taken; there must be at least one supervisor to prevent 3) the cleanup workers from falling from the equipment or suffering other injuries ； 5. If it is necessary to enter the coal crusher or coal screener for cleaning due to work requirements, all safety measures to prevent rotation must be taken, and the power supply to the related equipment at various levels must be disconnected ； 6. When carrying out cleaning tasks, it is necessary to use safety belts when required, to prevent cleaners from falling from the upper part of the machine ； 7. It is strictly prohibited to insert hands directly into the machine or any part of the body to remove debris ； 8. When debris is found in the coal crusher and coal screener and cannot be removed, notify the maintenance staff promptly to handle it. 268. What are the measures to prevent fires in MCC cabinets and various local control boxes? Answer: 1) It is strictly prohibited for rinse water to splash onto the MCC cabinets and various local control boxes ； 2. After use, the door of the on-site MCC cabinet must be closed tightly ； 3. If smoking or sparking is observed in the electrical equipment within the MCC cabinet during operation, stop the equipment immediately and contact maintenance personnel to handle it ； 4. Regularly inspect the dust accumulation inside the on-site MCC cabinets; once any issues are detected, record them as defects and contact maintenance personnel to address them, in order to prevent fires in the control panels caused by excessive dust accumulation ； 5. The fuses used in the MCC cabinet must be selected according to the specified capacity; it is strictly prohibited to use iron wires, copper wires, or other metals as substitutes ； 269. Safety measures to prevent coal depletion in the coal bin? Answer: 1. During shift duty, the programmed control operator should promptly verify the actual coal level in the coal bin with the on-site operator, to prevent coal supply interruptions due to faults in the level sensors ； 2. During their shifts, the shift leaders and programmed control operators should use the MIS at any time to monitor the operation of each grinding unit as well as any changes in their operation, in order to prevent coal supply disruptions in the coal bins due to changes in the grinding units ； 3. It is strictly prohibited to allow any debris to enter the coal bin, to prevent a shortage of coal in the bin due to blockages in the coal feeding pipe ； 4. Strictly implement the relevant regulations on using water spraying to control dust in the department, in order to prevent coal from scattering in the coal bins and any situations that could affect the load of the units ； 270. What are the main functions of coal conveying program control? Answer: Coal feeding and coal storage control functions ； Coal blending control function ； Monitoring and alarm function, accident alarm function ； Functions for displaying coal level in the coal bin, managing and monitoring it, as well as recording data; accident recall function ； Function for selecting coal feeding and mixing methods 271. What is the activation mode for the interlock in the coal conveying system? Answer: When programmatic interlock automatic control is used, the interlocks between devices are automatically activated. When manual control via program interlocking is used, the interlocking between devices is activated automatically. When manual control for unlocking is used. Interlock between devices is released. Unlocked operation is not permitted under normal circumstances. In the event of a system failure, the system can be stopped using the local pull-cord switch or the emergency stop button on the operator station (the engineer station during maintenance). 272. What are the inspection items for the programmed handover during coal transfer? Answer: The programmed duty operator reviews operation logs, equipment operation records, equipment defects, work orders, and work order records, etc., to understand the operating and standby status of the equipment as well as its maintenance conditions; they also check whether the equipment defects and abnormalities match the settings on the operator station (engineer station for maintenance purposes). The power and signal indicators on the programmable control cabinet are normal, and all the buttons, indicator lights, and switches in the various panels of the control room are present and undamaged. The programmable logic controller (PLC), operator station (engineer station for maintenance purposes) (PC), monitor (CRT), printer, UPS power supply, etc., should be in normal condition and functioning properly. The hosts, keyboards, monitors, mice, UPS units, etc. of each PC are all present and in good condition, and the video surveillance system is working properly. The equipment was put into trial operation; it started and stopped properly, and operated normally. The coal feeding mechanisms were intact (except for those used for equipment maintenance), and all displays as well as electrical panels and cabinets were functioning correctly. During shift handover when the equipment is operating normally. The ammeter display on the management unit and the industrial TV monitor should be checked in detail; only upon confirmation that everything is normal can one sign to take over the shift. If problems arise after taking over, the person who took over shall be held responsible. Upon taking over, the coal level in the coal bins was checked; the inspections conducted on site showed that the coal levels were normal, all being above 8 meters, and all the coal scrapers were in the raised position. All consoles, control cabinets, public address systems, air conditioners and other equipment and facilities, as well as tools, are complete, in good condition and operating properly. Verify the data from the electronic belt scale. The door and window glass, as well as the bathroom facilities, are in good condition. The cleaning of the areas under the responsibility of this position meets the standards for civilized production. 273. What are the inspection items before programmable control startup of coal transfer? Answer: 1) Based on the team leader’s instructions, determine a reasonable operation method and promptly issue relevant orders to each inspector in order to carry out inspections and preparatory work before the system starts operating. 2. Check that the power connections for each component are correct, have good contact, and that the plugs are properly inserted. 3. Check that equipment such as the CRT in the programming control room, the programming control host, the UPS power supply, television monitors, and monitoring manual operators are in good condition. 4. Check whether the broadcast call system of the coal conveying system is in a reliable standby state. 5 Check whether each baffle in the system is consistent with the designated operating mode. 6. Check whether each head telescoping device is in its normal working position. 274. In what situations should the insulation resistance of an electric motor be measured, and the measured data recorded in detail? Answer: 1) Newly commissioned motors. 2) Motors that are powered on for the first time after maintenance. 3) Motors that have been exposed to water or moisture. 4) When power needs to be restored to motors that have been without power for more than 5 days. 5) Motors that trip during operation. 275. What are the precautions for measuring insulation in electric motors? Answer: 1) Check whether the serial number of the measuring equipment is correct. Check that the power supply to the motor has been completely cut off, confirm that there is no possibility of a sudden power restoration, and use a qualified voltage tester to verify that there is no voltage present. Discharge the tested motor and cable. Select the appropriate measuring tool and check that it is in good condition; ensure that no one is working in the circuit. Select a suitable ground point and verify that it is indeed good, then disconnect the circuits that affect the accuracy of the measurement. The insulation measurement time must be no less than 1 minute. After the measurement is complete, discharge the device being measured and restore the circuits that affected the accuracy of the measurement. 276. The basic components and working principle of belt conveyors. Answer: Components of a belt conveyor: A belt conveyor mainly consists of the conveyor belt, drive equipment (motor, hydraulic coupling, reducer, elastic pin coupling), main drive drum, redirecting drum, tensioning drum, sets of parallel idler rollers, sets of trough idler rollers, sets of buffer idler rollers, trough-type self-aligning idler rollers, parallel-type self-aligning idler rollers, tensioning devices, cleaners, empty-section cleaners, guide chutes, frame, safety guards, protective covers at the head and tail ends, and various protection devices. Working principle: A belt conveyor is a continuous conveying machine that uses a belt for traction and loading to transport bulk materials; in power plants, it is mainly used for transporting coal. The belt wraps around the drive drum, redirecting drum, and tensioning drum to form a continuous loop; it is supported by parallel idler rollers and trough idler rollers, and a tensioning device applies a certain amount of tension to keep the belt in close contact with the outer surfaces of these drums. There is a certain coefficient of friction between the outer surface of the drive drum and the belt. As the drive drum rotates continuously, the friction between it and the belt drives the belt to move horizontally, thereby transporting the materials scattered on the belt in a continuous manner. 277. What are the inspections and precautions during belt conveyor operation? Answer: 1) During the operation of the equipment, the inspector must carefully listen to whether the sounds of the motor and gearbox are normal. 2. Check whether the temperature at each bearing seat is too high and whether the vibration levels exceed the standards; the vibration level at each location should be ≤0.1 mm, the temperature should be ≤800°C, the temperature rise should be ≤400°C, and the axial movement should be ≤2 mm. The temperature of the reducer oil should be ≤600°C, and the temperature of the motor should be ≤800°C. 3. The belt in operation should not deviate from its path; if a slight deviation is detected, it should be adjusted promptly. 4. The coal flow on the belt should be normal; it must not operate under overload conditions. If overload is detected, contact the coal transfer control operator immediately to adjust the coal supply amount. 5) During operation, close attention should be paid to the condition of the belt at the outlet of the conveyor chute and at the point where coal is discharged from the belt conveyor. If abnormal coal discharge or flow is detected, the cause must be identified immediately and corrective action taken right away. 6. Pay special attention to the coal discharge from the head coal discharge pipe; if blockage is detected in this pipe, the machine should be stopped immediately. 7. Check whether various idlers and rollers rotate smoothly, if there are any abnormal noises, and whether all types of cleaners are functioning properly. If the equipment is not functioning properly, the inspector shall report to the shift leader based on the progression of the defect, or stop the operation of the equipment. 8. All coal discharge pipes should be unobstructed with no severe coal accumulation; the operator determines the operating mode and frequency of the vibrators based on the quality of the coal. 9. The tensioning device is operating properly; the weight should not reach its extreme position, the track should be smooth without any deformation, there should be no sticking in the ropes or wheels, and the steel wire rope should not have any short strands. 10. All protective devices should operate properly. 11. When a cut on the belt is detected, stop the machine immediately by pulling the emergency stop cord, and report to the shift leader and department supervisor. 12. Check the moisture content of the coal; the dust concentration in the system should not be too high, and adjust the water flow rate of the spray device at the outlet of the feed chute promptly. The water spray volume must not be too high, so as not to affect the boiler coal grinding system. 13. It is strictly prohibited to operate the telescopic head while it is in operation. 14. It is strictly prohibited to clean the coal adhering to the deflection drum and drive drum while the conveyor is in operation. 15. It is strictly prohibited to clean, sweep, or wipe any rotating parts of the belt conveyor. It is strictly prohibited to clean coal deposits, dust, and other debris accumulated under the belt conveyor. 16. It is strictly prohibited to cross the belt at any time; if it is necessary to do so, one must use the access bridge. 17. When the sealed leather strip comes out, it must not be adjusted by a single person. 18. It is strictly prohibited to use belt conveyors as other means of transportation. 19. It is strictly prohibited to start the belt conveyor under heavy load. 20. In case of the following situations, the emergency pull-cord switch should be used to shut down the machine immediately. (1) The motor overheats and starts smoking. (2) There are occurrences that threaten personal safety. (3) Blockage of the coal dropping pipe. (4) Scratches or tears in the belt. (5) A fire breaks out in the system (e.g., the belt catches fire, electrical equipment catches fire, etc.). 278. The safe operation of the coal transportation system is of great importance for the safe generation and supply of electricity across the entire plant; all employees must attach great attention to it in order to prevent accidents from occurring Answer: 1) Fire in the coal conveying system; 2) Accidents resulting in minor injuries or worse; 3) Prolonged tearing of conveyor belts; 4) Empty coal storage bins; 5) Damage to key equipment in the system; 6) Disruption of all methods for feeding coal into the system; 7) Entry of large objects into the coal storage bins, causing the boiler’s coal grinders to stop operating. 279. What are the general principles for handling failures in the coal conveying system? Answer: As the first stage in thermal power generation, the coal transport system requires the fuel department to strictly adhere to the principle of \"safety first, prevention foremost\" in order to ensure its safe, economical, and stable operation. In the event of any abnormalities or failures in the equipment or system, it is necessary to address such issues promptly, always prioritizing the protection of personnel, equipment, and the power grid. 1) When a equipment failure occurs and the equipment cannot operate, it is necessary to report to the shift supervisor as well as the company’s and department’s on-duty managers first, and actively work to restore system operation to ensure a supply of coal for the boiler. If equipment failures or potential hazards are detected, they should be reported to the shift leader and the programming operator promptly so that the cause of the failure can be identified as soon as possible. Enter equipment defects into the MIS promptly and contact the maintenance department to resolve them. For equipment that has been shut down due to a fault, no one shall restart it until the cause is identified and the defect is rectified. Equipment that must operate despite having defects should have appropriate safety measures put in place depending on the nature of those defects, in order to prevent them from worsening. After an accident occurs, the relevant teams must take proactive remedial actions to prevent the accident from spreading. All relevant personnel must cooperate in a practical and realistic manner with the departmental or company officials to conduct an investigation and analysis of the accident in accordance with the principle of \"not letting anything go unchecked.\" 280. What is the device number of the system? Answer: Based on the characteristics of the equipment and process flow in the coal transportation system, numbering is done in the order of the flow direction. The System A and System B do not intersect; when standing between the two devices facing the direction of the flow, the right side corresponds to System A, while the left side corresponds to System B. The number of the coal plow corresponds to the unit and the coal bunker. 281. What are programmed automatic coal blending, programmed manual coal blending, and on-site manual coal blending? Answer: For the programmable automatic coal blending method: By clicking “Programmable Blending” at the operator station in the control room (engineer station during maintenance), the coal spreaders on the conveyor belts of the coal bins will fill the bins in sequence, starting from the bin with the lowest coal level (except for the maintenance bin), moving upward. The programmed duty operator then manually activates another belt conveyor in the coal bin using programmed interlocking, and by clicking on the “Programmed Allocation” system, the coal is allocated to the bins in order, starting from the lowest bin first and moving to the higher ones. Programmed manual coal blending: On the operator station in the control room (engineer station during maintenance), click “Manual blending” to perform individual up-and-down movements of the coal spreader, thereby filling all the coal bins. On-site manual coal blending: This involves operating the coal spreaders one by one right at the equipment location, with manual monitoring of the coal level in the silos to ensure that they are filled to capacity. 282. What are the inspection items after the conveyor stops? Answer: 1) Check that all parts of the conveyor belt are undamaged. 2. Check each drum for coal sticking; if there is coal stuck, stop the machine and clean it. 3. Clean the hygiene on the cleaning drive device. 4. Inspect and clean the coal chute and coal grates of any stuck coal and debris. 5) Check whether the belt is scratched and whether the joints are in good condition. 6) Check whether all auxiliary equipment is in normal condition and intact, and whether the water, heating, electrical, and lighting systems are functioning properly. 7) Upon detecting equipment defects, contact the coal transfer control operator promptly and fill out an equipment defect report. 8) Keep the area under one’s responsibility clean. 283. What are the basic components and working principle of a coal crusher? Answer: Composition: The ring-type coal crusher is mainly composed of a housing, a cover, impact plates, rocker arms, a screen plate regulator, a main shaft, an ring hammer shaft, gear rings, rings, screen plates, coal crushing plates, an iron removal chamber, a hydraulic system, a hydraulic coupler, a motor, etc. Working principle: It primarily uses the hammer rings on the high-speed rotating rotor to apply hammering forces in order to break up coal lumps. When these coal lumps enter the coal crusher chamber, they are struck by the rapidly rotating rings and toothed rings and pressed against the crushing plate. The coal is broken down through shearing, compression, rolling, and grinding by the hammer rings. Indestructible materials such as iron and wood are carried by the toothed rings to the iron removal chamber. The crushed coal passes through the holes in the screening plate and enters the coal discharge pipe, thus completing the entire process of coal crushing. 284. Inspections and precautions during the operation of coal crushers: Answer: 1) The inspector should regularly check the temperature and vibration at each bearing seat while the equipment is in operation. The temperature rise of the main bearing ≯ 400°C; the maximum temperature ≯ 800°C, and the maximum amplitude ≯ 0.03 mm. There is no powder or coal leakage at various inspection doors and the door to the iron removal chamber, and no oil leakage from the hydraulic coupler. Check whether the coal supply pipes at the top and bottom are leaking coal. Check whether there are any abnormal noises inside the coal crusher, at each bearing seat, and in the motor. After the maintenance of the next level of belts (replacing the sealing elements on belt #5), it is even more necessary to pay close attention to the coal feeding and discharging conditions of the coal crusher. If a blockage is detected, stop the machine immediately; it can be restarted only after the cause has been identified. It is strictly prohibited to open the inspection door or the door of the iron removal chamber while the equipment is in operation or before it has come to a complete stop. It is strictly prohibited to wash the motor directly with water. It is strictly prohibited to clean or wipe the rotating parts of the equipment while it is in operation. It is strictly prohibited to enter the coal crusher to carry out tasks such as cleaning or maintenance without proper safety precautions. It is prohibited to start the coal crusher under load. 285. What are the basic components and working principle of the impeller coal feeder? Answer: Basic components: The impeller coal feeder is mainly composed of a frame, a main drive system, a traveling drive system, a remote control device, a control box, and a dust removal system. The main drive system consists of a motor, reducer, drive shaft, impeller, electrical speed control system, etc ； The traveling drive system consists of a motor, a reducer (pinion cycloidal), traveling wheels, couplings, etc. Working principle: The electric control box controls the rotation of the motor; through a reducer and a drive shaft, the impeller inserted into the gap of the coal unloading chute is made to rotate, which in turn causes the leaf claws to move rotatably and push the coal out of the chute. The coal then falls onto the belt conveyor below via the coal discharge pipe. During the coal feeding process carried out by the impeller feeder, it is possible to feed coal while the machine remains in place, or it is also possible to feed coal while the machine is in motion. The movement of the entire unit is achieved by the forward and reverse rotation of a motor with a constant speed. When the impeller coal feeder reaches one of the ends or when the two impeller coal feeders get close to each other, their travel switches or proximity switches activate, causing the impeller coal feeder to operate in the reverse direction automatically. The speed of the impeller is controlled by an inverter, which enables the coal feeding amount supplied by the impeller coal feeder to be adjusted. 286. What are the precautions for operating the impeller coal feeder? Answer: Whether the impeller coal feeder is operated locally or remotely via programmed control, the following operating methods are strictly prohibited (except in abnormal situations): 1) It is strictly forbidden to change the direction of movement of the impeller coal feeder while it is in motion. To change the direction of movement, it is necessary to first stop the operation of the moving system, then press the button for the opposite direction, and the device will change its direction of movement. It is strictly prohibited to start the impeller coal feeder without setting the impeller speed to “zero”. It is strictly prohibited to operate the traveling drive system when the coal feeding mechanism is not functioning properly. It is strictly prohibited to activate the impeller coal-shifting mechanism when the lower belt conveyor is not operating properly. It is strictly prohibited to stop the impeller coal feeder without adjusting the impeller speed to “zero”. It is strictly prohibited to stop the operation of the impeller coal feeder while in motion. It is strictly prohibited to place other items on the tracks, such as tools or clothing. During operation, pay attention to checking the coal feeding rate and ensure even coal supply to maintain normal unloading from the coal chute. 287. What is the composition and working principle of a roller screen? Answer: A roller screen mainly consists of a transmission mechanism and the screen body, as well as an electrical control unit. The transmission mechanism is made up of ten sets of motors plus cycloidal pinwheel reducers (for single-axis drive), while the screen body is composed of metal components, shafts (ten in total), and screening elements. The electrical control unit includes frequency converters, PLC programmable controllers, and other components. Working principle: The roller screen operates through 10 sieve shafts arranged side by side, rotating in the same direction. When the material to be screened (coal) falls on the first three shafts on the screen surface, it spreads out quickly; the rotating shafts and screen plates then push this material forward, causing it to roll. At the same time, particles of material that are smaller than the size of the screen holes fall downward due to their own weight and the rotational force of the screen plates, while particles larger than those screen hole sizes move forward along the screen surface until they reach the outlet of the roller screen and fall into the coal crusher. 288. Basic components and working principle of the bucket wheel conveyor: Answer: Components: The bucket wheel stacker-reclaimer is mainly composed of a cantilever belt conveyor, a bucket wheel mechanism, a rotating mechanism, a tilting mechanism, a traveling mechanism, a tail car mechanism, a gantry frame, a dust removal device, an operator’s cabin, a hydraulic system, power supply units, cable winding mechanisms for communication purposes, various protection devices, and an electrical system (upper electrical room and lower electrical room). Working principle: The bucket wheel mechanism is installed at the front end of the cantilevered belt conveyor and rises and falls together with the conveyor in order to accommodate coal at different heights. As the bucket wheel rotates, when the bucket turns downward, it scoops coal into the bucket; when the bucket wheel continues to rotate to its highest position, the coal falls due to its own weight, and the arc-shaped coal guide plate directs the coal toward the receiving chute, from where it is transported to the central coal discharge pipe by a cantilevered belt conveyor. Below the coal dropping pipe is the tail car belt conveyor that is connected to the surface belt; coal falls from the central coal dropping pipe onto this tail car belt conveyor, and from there it is transported via the surface belt to the coal transmission system, thereby completing the material collection process by the bucket wheel conveyor. When stacking coal is required, the tail car is raised to the upper part of the cantilevered belt conveyor. The coal supplied by the system falls onto the cantilevered belt conveyor via the surface belt and the tail car belt. The belt conveyor then reverses direction, transporting the coal to the front end where it is deposited in the coal storage area, thus completing the stacking process. 289 What are the precautions during the operation of a bucket wheel conveyor? Answer: It is necessary to contact the programmed duty operator before stacking or removing coal. It is strictly prohibited to consume alcohol within 8 hours before operating the bucket wheel loader at work. It is strictly prohibited to move the heavy vehicle without activating the audio alarm. It is strictly prohibited to change the operating mode of the bucket wheel conveyor’s tail car while the #3 belt is in use. It is strictly prohibited to start belt #3 during the process of changing the tail car of the bucket wheel conveyor. It is strictly prohibited to move the main crane or start belt #3 until it is confirmed that the tail car of the bucket wheel conveyor is properly connected. When performing rapid shunting with the large vehicle, the cantilever frame must be positioned at an angle of less than 300 degrees to the conveyor belt track. The coal intake depth of the bucket wheel shall not exceed 1000 mm. It is strictly prohibited to reverse the rotation, movement, or tilt of the bucket wheel conveyor while it has not come to a complete stop. In winter, when a collapse at the coal extraction site presses down on the bucket wheel, it is strictly prohibited to operate the lifting and lowering mechanism as well as the rotating mechanism. It is strictly prohibited to operate the rotation and tilting mechanisms of the bucket wheel loader while the hauler is in motion. It is strictly prohibited for the bucket wheel conveyor to operate under overload conditions. It is strictly prohibited for the cantilever frame to pass over the rear car. Before operation, it is necessary to check that all protective devices are in good condition and function smoothly and reliably before proceeding with the operation. When electrical or mechanical faults such as those in motors or reducers are detected, the machine must be stopped for repairs before operation can resume. The bucket wheel crane operator should conduct a thorough inspection every hour; additional inspections should be carried out when operating the crane while it is malfunctioning. The main checks include vibration and temperature rise in various areas; the temperatures should be within specified ranges (700 for motors, 750 for bearings, and 700 for reducers). The tightness of all components in the hydraulic system is also checked, as well as whether the system’s oil pressure is within the specified limits. There should be no vibration or abnormal noises in the pipes. Regularly inspect the cable reel mechanism: check whether the exterior of the cable reel is scratched, crushed, or broken, whether there is any jamming in the reel, and whether the rotation of the cable reel is synchronized with the movement. During coal loading and unloading operations, if larger pieces of iron, wood, stone, or large coal blocks (the four types of large debris) are detected, the machine must be stopped immediately for cleanup to prevent damage to the conveyor belt or blockage of the coal discharge pipes. During operation, if a situation that endangers the safety of personnel and equipment is detected, the machine should be stopped immediately by pressing the emergency stop button. When the wind force reaches level 6, operations of the bucket wheel conveyor must be stopped. Take wind protection measures: clamp the rail clamps, position the cantilever frame on top of the coal pile facing the wind, and anchor it with an anchor. When working in windy conditions, it is necessary to first check the braking and rail-clamping devices of the bucket wheel machine. Drain all the water from the dust removal system before the temperature drops below 0°C. When the temperature is below 15°C, the heater must be turned on before operating the bucket wheel loader. The two bucket wheel conveyors should have one in loading mode and the other in unloading mode, with the roles switched twice a week. All lighting of the bucket wheel conveyor should be turned on at night. 290. What tasks should be carried out after the bucket wheel conveyor is shut down? Answer: 1) Check whether there are any bruises or scratches on all rotating parts. Check the hydraulic system for oil leaks or other abnormalities. Check whether there are any defects or malfunctions in various protective devices, limit switches, proximity switches, etc. Before shutting down the machine, check whether the rail clamps and anchoring devices are properly clamped and anchored. Check whether the cable is in good condition. Check each blanking point for coal sticking; remove it immediately if present. Keep the sanitary area under the responsibility of this position clean. Contact the programming duty officer to fill out the equipment defect form. Basic components and working principle of the dust collector: Answer: Basic components: The water bath type dust collector is mainly composed of a dust collector housing, air inlet pipe, water inlet pipe, air outlet pipe, water barrier plate, motor, fan, water inlet valve for cleaning, slurry discharge valve, water level detection device, overflow valve, etc. Working principle: The motor drives the fan to rotate, creating a negative pressure at the inlet of the fan. Under this negative pressure, a negative pressure is generated on the side containing clean air inside the housing, while the side with dusty gas has positive pressure. As a result of this pressure difference, irregular ripples are formed on the water surface. At the same time, a gap is formed between the dusty gas side and the clean air side. The dusty gas rapidly passes through the water surface and makes its first contact with it; the water absorbs the dust present in the dusty gas, simultaneously carrying away numerous water droplets. These water droplets come into contact with the dusty gas on the clean air side, and once again the dust comes into contact with the water droplets. The dust is absorbed by the water droplets and continues to rise before being stopped by the water baffle and returning to the water surface. During the two contacts with water, the majority of the dust in the dusty gas is adsorbed by the water and settles in it; as a result, the dusty gas becomes cleaner and is discharged into the atmosphere by a fan. 291. What are the basic components and working principle of a bag filter? Answer: This dust removal unit consists of an air intake chamber, a ash discharge chamber, a filtration chamber, a clean air chamber, a fan, and ash cleaning components. Working principle: When dust-laden gas enters the filtration chamber through the air inlet and passes through the filter bags from the outside inward, the dust is trapped on the outer surface of the filter bags. The clean air enters the bags and is then discharged into the atmosphere through the air outlet via an ejector and a clean air chamber. As the dust on the surface of the filter bags increases, causing the equipment resistance to rise to the set value, the differential pressure controller generates a signal. The controller then sends a signal to activate the injection system; compressed air is ejected through the output pipe and enters the annular channel of the ejector tangentially, before being sprayed downward at the speed of sound. This creates a vacuum at the upper part of the ejector, and some of the air in the clean air chamber is drawn in (known as secondary airflow). The compressed air together with this secondary airflow enters the filter bags, causing them to expand rapidly and generating shock vibrations that create an external airflow. This airflow blows away the dust adhering to the outside of the filter bags and between their fibers, thus cleaning the filter bags. The cleaned dust falls to the ash discharge port and is removed; after the injection process is completed, the filter bags return to their filtering state. 292. What are the steps for local start/stop operation of a belt-type magnetizer? Answer: 1) Set the changeover switch “Programmed/Local” to the “Local” position. Open the door of the control cabinet and sequentially close the air switches QF1, QF2, QF3, and QF4. Start the belt first, then start the excitation. 4) Rotate the “adjustment knob” (clockwise to increase), gradually raising the current to 10–15A. 5) When shutting down, stop the excitation first, and then stop the belt. 293. Basic components and working principle of the disc type magnetizer: It consists of an excitation coil, a housing, a suspension mechanism, a traveling mechanism, a locking device, and a control cabinet. Working principle: The magnetic field generated by an electromagnetic magnet remover is a non-uniform magnetic field. When ferromagnetic objects enter this non-uniform magnetic field, they experience different degrees of magnetization depending on their position; the strength of the magnetic field also varies. The end with a higher degree of magnetization experiences a greater force, while the opposite end experiences a smaller force. Therefore, the force exerted on an object in a non-uniform magnetic field is uneven; its resultant force is greater than 0, causing the object to move toward the side where the force is stronger. This is how ferromagnetic objects move in a directed manner within a magnetic field. After the iron remover has been in operation for a while, another iron remover moves to its working position and starts working, while the current iron remover moves to the waste-iron discharge position to discard the iron. 294. Inspection before handover and startup of the sewage pump: Answer: 1) Check that the foot screws of the motor and pump body, as well as all the connection bolts, are tight and not loose. Check whether the motor’s wiring and grounding wires, as well as the protective cover, are in good condition. Check whether the automatic start/stop device of the sewage pump is functioning properly and whether the water level is at the normal level. The coupling connection bolts are intact, and the rotor rotates smoothly. There is no leakage of water or air from the pump body, the outlet pipe, or the inlet pipe. The sludge in the sump wells and coal settling tanks is in normal condition. 295. What is “four standards in one”? Answer: It is a comprehensive management system established within the framework of the ISO9001, ISO14001, OHSAS18001, and NOSA Five-Star safety, health, and environment management systems. Based on the GB/T19001-2000 standard, it integrates the requirements of GB/T24001-2004, GB/T28001-2001, and CMB253 2004 management standards, thereby achieving integrated management of quality, environment, and occupational health and safety. 296. The policy of the company’s quality, safety, health, and environment management system is: people-oriented, a combination of prevention and control, safety and reliability, energy conservation and environmental protection, health and civilization, integrity and compliance, the pursuit of excellence, and spreading light. 297. What are hazard sources, hazard identification, risk, and risk assessment? Answer: Hazard source: A source or condition that may cause injury or occupational diseases to persons, property damage, or damage to the workplace environment, or a combination of these. Hazard identification: The process of recognizing existing hazards and determining their characteristics. Risk: The combination of the likelihood of a specific hazardous event occurring and its consequences. Risk assessment: The entire process of evaluating the level of risk and determining whether it is acceptable. What does 298.5W1H mean? What–What to do? Why—why do this? When–When should it be done? Where – Where to do it? Who—who will do this work? How – What method should be used to do it? 299. What are the “four always” principles that are adhered to regarding issues of quality, safety, health, and environmental protection? Answer: Everything has a responsible person, everything follows established rules, everything is under supervision, and everything can be traced back to evidence. 300. Under what circumstances should braking devices be installed? Answer: When the inclination angle of a belt conveyor exceeds 40 degrees, a braking device is generally installed to prevent reverse rotation in the event of a shutdown under heavy load. 301. What is the company’s core mission? Answer: To provide high-quality electricity to society, to create substantial returns for shareholders, and to bring a better life to employees. 302. Basic behavioral norms for employees: Love for the country and the company; dedication and loyalty; serving society and contributing to its development; abiding by laws and regulations; integrity, diligence, and pragmatism; innovation and strong professional skills; a willingness to help others; courtesy and civility; taking good care of public property and protecting the environment; respecting the elderly and caring for children; equality between men and women; harmonious families; treating neighbors as friends; having graceful manners, being friendly and enthusiastic, honest and trustworthy; showing understanding and tolerance. 303. Job-specific norms for employees? Strict management to ensure safety; adherence to standards and compliance with regulations; fulfilling duties responsibly; high quality and efficiency; close cooperation for mutual progress; continuous learning; striving to surpass oneself. 304. Briefly describe the production process in a thermal power plant? Answer: The production process in a thermal power plant can be summarized as follows: The chemical energy of fuel is converted into thermal energy through combustion, which is used to heat water into steam at a certain pressure and temperature. This steam then drives a turbine, converting thermal energy into mechanical energy that causes the rotor to rotate; finally, a generator converts this mechanical energy into electrical energy. 305. What is belt deviation? Answer: During the operation of a belt conveyor, sometimes the center line of the belt deviates from the center line of the conveyor and moves to one side; this phenomenon is known as belt deviation. 306. Briefly describe the working principle of a belt conveyor? Answer: When the belt conveyor is in operation, the motor drives the drive roller of the conveyor belt; the friction between the drive roller and the belt enables the belt to move, and materials such as coal are carried along the belt to the discharge point where they are unloaded. 307. What causes severe vibration and abnormal noises in a reducer? Answer: (1) The anchor bolts are loose. (2) The clearance between the two end surfaces of the coupling does not meet the requirements. (3) The alignment does not meet the requirements. (4) Shaft bending or gear breakage. (5) There are miscellaneous items inside the machine. (6) Bearing damage. 308. What are the advantages of belt conveyors? Answer: Compared with other types of conveying equipment, belt conveyors have the advantage of ； It features high production efficiency, stable and reliable operation, continuous and uniform conveying, low operating costs, easy maintenance, and facilitates automatic control and remote operation. 309. What are the main components of a belt conveyor for coal transport? Answer: A belt conveyor consists of a conveyor belt, idler rollers and frame, a driving device, a tensioning device, deflection drums, a cleaner, etc. 310. What is the self-aligning principle of automatic self-aligning rollers? Answer: When the tape deviates from its path, the edge of the conveyor belt comes into contact with the force roller that hangs outside the return frame. When the force roller is subjected to the force exerted by the belt edge, it exerts a torque on the rotating frame, causing it to rotate by an angle, thereby achieving centering. 311. What are the characteristics of electric drum motors? Answer: An electric drum is a driving device used for conveying coal via belt conveyors. Its features include a compact structure, small size, neat appearance, safe operation, light weight, low consumption of metal materials, and low cost; however, it is complex to maintain. 312. What is a equipment accident? Answer: Losses caused by the damage to mechanical, electrical equipment, pipelines, buildings, etc., due to various reasons, are referred to as equipment accidents. 313. What are the key points for aligning a coupling? Answer: (1) Place a straight edge at the relative positions of the coupling; after identifying the direction of the deviation, make rough adjustments to bring the centers of the couplings closer together and to ensure that their end faces are aligned, thereby laying the foundation for precise alignment of the coupling. (2) Install the alignment tool and measure the relative position of the center. (3) Fix the position of the driven motor, then adjust the motor to align the centers. After adjustment and measurement, the specified requirements are met. (4) Based on experience, it is more convenient and faster to adjust the end face first and then the center when aligning; once skilled, the adjustment of both the end face and the center can be carried out simultaneously. 314. Explain the role of lubrication? Answer: Lubrication plays an important role in the proper operation and maintenance of mechanical equipment. It can control friction, reduce wear and tear, cool down, prevent rust and corrosion on the friction surfaces, provide sealing, transmit power, and reduce vibrations. 315. What are the advantages of gear transmission? Answer: The advantage of gear transmission is its compact structure ； Wide range of applications ； It ensures that the gear ratio remains constant ； High mechanical efficiency ； It operates reliably and has a long service life, with low stress on the shafts and bearings. 316. What are the components of a hydraulic system? Answer: A hydraulic system consists of a power section, an actuating section, a working medium, and auxiliary sections. 317. What are the characteristics of throttle valves? Answer: The throttle valve is used to regulate the flow rate passing through, in order to change the operating speed of the cylinder ； The throttle valve can control the amount of bidirectional flow. When the oil flow reverses direction, the one-way throttle valve functions as a check valve, allowing the reverse-flowing oil to pass through freely without being controlled by the throttle valve. 318. What is the purpose of centering rotating machinery? Answer: In general, centering machinery refers to adjusting the axis lines of the driving and driven shafts to be on the same straight line, thereby ensuring balanced operation. This goal is achieved by measuring and adjusting the corresponding positions of the two half-couplings that are properly installed on the drive and driven shafts. 319. Why are sweepers installed on belt conveyors for coal transportation? Answer: After the belt is unloaded, fine coal slag often sticks to its surface. To keep the belt clean, a cleaner must be installed to sweep the surface of the belt. 320. What is the function of an iron remover? Answer: An iron remover is used to remove metal objects of various shapes and sizes mixed in coal during transportation, thereby ensuring the safe operation of coal conveyors, coal crushers, and coal grinders. 321. What are the basic principles for setting up interlocks between various equipment in the coal conveying system? Answer: The basic principle is that, under normal circumstances, the equipment must be stopped in the direction of coal flow ； At startup, start the equipment in the opposite direction to the coal flow. 322. Why does the pump have pressure in a ring coal crusher but no oil output, or why does the volumetric efficiency decrease? How to eliminate it? Answer: The reasons are: (1) Damage to the sealing parts inside the pump ； (2) Dirt has been inhaled, causing severe wear on the sliding parts. Remediation method: (1) Replace the seal ； (2) Remove debris or replace worn parts. 323. What are the main components of a screw coal unloader? Answer: (1) Metal frame section; (2) Traveling mechanism for the main frame; (3) Screw lifting mechanism; (4) Screw rotating mechanism. 324. What are the advantages of a ring-type coal crusher? Answer: (1) Large crushing capacity, low power consumption, high efficiency ； (2) Simple structure, small footprint, high stiffness, and lower mass compared to hammer and impact types ； (3) The guarantee strength is below 30 mm and the discharge is uniform ； (4) Since the hammer ring can swing freely, it automatically retracts when it encounters a hard object ； (5) Small machine volume, low air volume, and minimal coal dust leakage ； (6) Low operating noise ； (7) Low unit vibration ； (8) The materials used in the unit are appropriate, ensuring a long service life. 325. What are the quality requirements for manufacturing belt joint interfaces? Answer: (1) The unevenness of equal division at various steps of the belt shall not exceed 1 mm ； (2) The outer surface shall be smooth, without any cracks, and it is not allowed to accidentally cut away a layer of canvas. The error length must not exceed 1/10 of the bandwidth ； (3) When cleaning the residue from the grinding wheel, ensure that all residue is removed ； (4) The edge of the belt at the interface should be a straight line, with a straightness tolerance of less than 0.3% ； (5) The interface should be able to be used for over one year. 326. Describe the working principle of a high-voltage electrostatic precipitator? Answer: When a gas containing dust particles passes through a high-voltage electric field, the gas is ionized due to corona discharge at the cathode. At this point, the negatively charged gas ions, under the influence of the electric field force, move toward the anode. During this movement, they collide with dust particles and adhere to them, causing the dust particles to become negatively charged as well. After becoming charged, the dust particles move toward the anode under the force of the electric field. Upon reaching the anode, they release the electrons they are carrying, which then deposit on the anode plate, while the purified gas is discharged from the dust collector. 327. Describe the operation sequence of the bucket wheel conveyor? Answer: (1) According to the operational requirements, make the necessary preparations; once the start command is given from the control room, turn the interlock knob to the interlocked position ； (2) Once the air switch is closed, the power indicator light on the control panel turns on ； (3) Turn the operation power knob to the on position ； (4) After selecting the position, start \"Rear car descend\" or \"Rear car ascend\“. First, press the \"Release clamp\" button; the light will go out once it is fully released. Operation is possible only when the vehicle is in motion; the electric bell must be activated each time it moves to give a warning ； (5) The forward and backward movement of the heavy vehicle is controlled by a controller. 328. Explain the reasons for the entire tape drifting to one side Answer: (1) The center of the driving drum is not perpendicular to the center of the belt ； (2) The idler bracket is not perpendicular to the belt ； (3) The center of the driven drum is not perpendicular to the center of the belt ； (4) Accumulated coal adheres to the surfaces of the driving or driven drums and idler rollers ； (5) Improper belt joint alignment ； (6) The material falls off at a position offset from the center of the belt ； (7) Debris is jammed. 329. What is the model of the car dumper at our factory? Answer: (Type FZ1-2A”C”) 330. What is the maximum load capacity designed for the platform of the dump truck equipment in our factory? Answer: (100T) 331. What interlock conditions must the main unit meet when using a train pulling machine to pull trains? Answer: (Body at zero position, backing plate in place, clamping in place) 332. What are the main components of our factory’s car turning system? Answer: (Car dumper body, car shifter, transfer platform, wheel clamps, special-shaped transfer platform) 333. Into which two categories can car dumpers be divided based on their unloading method? Answer: (Rotor type, tilting type) 334. What are the four operating methods for the car dumper systems in our factory? Answer: (Manual, local manual, single-unit automatic, interlocked) 335. What type of drive system is used in our plant’s car dumper system? Answer: (Gear transmission) 336. What are the requirements for a vehicle transfer platform to be able to transfer vehicles? Answer: (1. The empty vehicle is already positioned on the transfer platform; 2. The boom of the vehicle handling machine is raised; 3. The alignment pins of the transfer platform are reset; 4. The tensioning device is in its clamping position; 5. The vehicle pushing machine is in its original position.) 337. What is the rotation cycle of the rotor of the car flipper at our factory? Answer: (60S) 338. What is the maximum pulling capacity of the truck dispatcher in our factory? Answer: (4500 tons) 339. What are the pulling speed, hooking speed, and traveling speed of the crane in our factory? Answer: (0.6m/s 0.3m/s 1.4m/s) 340. What is the operating speed of the vehicle transfer platform at our factory? Answer: (0.63 m/s)³ 41. What is the model of the reducer for the trolley machine in our factory? Answer: (Model ZSY-180) 342. State the four automatic stop positions of the car shifter during the operation of the car dumper system Answer: (In-place at the vehicle handler, in uncoupling position, positioned inside the unit, positioned inside the vehicle transfer platform) 343. What are the conditions for the vehicle handler to return? Answer: (The last set of wheel pairs on the car passes through the one-way stopper) 344. What does the hydraulic system of the car transfer platform control? Answer: (Counterpin, tensioner) 345. What is the clamping force of the wheel clamps in our plant’s car dumper system? Answer: (20T) 346. State what the operating speed of the cart machine is and what its maximum travel distance is Answer: (0.7 m/s, 44 M) 347. What are the different types of unloading lines for car dumpers based on their layout? What type is my factory? Answer: (Through-type, reversing type, reversing type) 348. What safety measures has our department established and implemented to prevent any movement of the car dumper itself? Answer: (When the car dumper system is not in operation, it is prohibited to store carriages inside the unit; in special cases where temporary storage of carriages is necessary, the retaining plates must be positioned against the carriages and secured firmly.) 349. What is the model of the bucket wheel conveyor in our factory? Answer: (Model DQL1000/1500－30) 350. What is the rotation radius of the bucket wheel conveyor in our factory? Answer: (30M) 351. What is the diameter of the bucket wheel of our plant’s bucket wheel conveyor? Answer: (5.4M) 352. What is the speed at which the bucket wheel can change its angle? Answer: (Ascending: 3.39 m/min; Descending: 4.93 m/min) 353. What is the rotation angle of the bucket wheel conveyor in our factory? Answer: (±110 degrees) 354. What are the different stacking methods for bucket wheel conveyors? Answer: (Rotation, positioning, movement) 355. During loading and unloading operations, what distance should be maintained between the bucket and the surface of the coal yard? Answer: To ensure that the bucket does not collide with the coal yard floor and damage the equipment. (At least 0.5M or more) 356. What are the belt width and belt speed of the belt conveyor installed on the bucket wheel conveyor in our factory? Answer: (1.4M, 2.5m/s) 357. At what gear is the electric actuator set when the bucket wheel conveyor is in stacking mode, and at what gear is it set during material retrieval operations? Answer: (Extend, retract) 358. At what wind force level during operation should the bucket wheel conveyor be stopped, and what should be activated instead? And place the bucket on the coal pile. Answer: (Level 7, Rail-Clamping Anchoring Device) 359. What should be avoided as much as possible during operation to prevent movement of the bucket wheel crane’s arm? Which type of rotation should be prioritized? What is absolutely prohibited before the arm rotation has completely stopped? Answer: (Frequent rotation, large angles, reverse operation) 360. Where should the bucket wheel be placed after the bucket wheel conveyor stops working? Where is it absolutely forbidden to place the bucket wheel when there is no work required? It even stopped above the #7 belt trestle. Answer: (On the coal pile, on the concrete floor) 361. What are the two components of the bucket wheel conveyor drive system? Answer: (Internal curve hydraulic motor, axial variable pump) 362. What are the two basic methods of material retrieval used by bucket wheel conveyors? Answer: (Slope-layer material retrieval method, horizontal full-layer material retrieval method) 363. Based on their structural design, into which three types can bucket wheel conveyors’ buckets be classified? Answer: (formatted, unformatted, semi-formatted) Into which three types can the buckets of a 364 bucket wheel conveyor be divided? Answer: (Forward-leaning, backward-leaning, standard) 365. Into which three main types can the tail car of a bucket wheel conveyor be classified based on its function? Answer: (Fixed-type, fold-back type, through-type) 366. What are the two most common power supply methods for bucket conveyors? Answer: (Power supply via rigid cable, power supply via flexible cable) 367. What are the three types of drive methods for bucket wheel drives? Answer: (Hydraulic drive, mechanical drive, hydraulic-mechanical combined drive) 368. To reduce the traveling time, what type of motor is used for the drive motor of the bucket wheel loader? Which one is for shunting speed? ； Which one is the working speed? Answer: (Two-speed motor, fast, slow-fast) 369. What are the characteristics of bituminous coal? Answer: Low volatile content and high carbon content. 370. Is the moisture in coal an unnecessary component or a useful one? Answer: Inactive components. 371. What is the volatile matter content of bituminous coal? Answer: 10%-45%. . 372. What are the two methods for analyzing the composition of coal? Answer: Elemental analysis and industrial analysis. 373. What are the main pollutants from thermal power plants? Answer: Sulfur dioxide. 374. What effects does an increase in the surface moisture of coal have on the coal transfer pipelines in the coal bin and the coal feeder? Answer: Adhesion, blockage. 375. At what temperature above threshold must the coal pile be turned over, loosened, or watered to cool it down? Answer: 60 degrees. 376. To carry out effective combustion management and prevent spontaneous combustion in coal yards, what methods should be adopted during coal stacking operations? Answer: Layered compaction. 377. What type of fire extinguisher should be used in case of a fire involving potentially live electrical equipment, as well as generators and motors? Answer: Dry chemical fire extinguishers, carbon dioxide fire extinguishers, or 1211 fire extinguishers. 378. Since lump coal has a small contact area with air and is easy to ventilate for heat dissipation, is the possibility of spontaneous combustion lower or higher? Answer: Smaller. 379. What is the volatil content of anthracite? Answer: Less than or equal to 10%. 380. What proportion of the operating costs of coal-fired power plants does the cost of coal account for? Answer: 70%. 381. What is the main reason for the spontaneous combustion of coal, namely, what causes it to come into contact with in the air? Answer: Oxygen. 382. Which property of coal determines the difficulty of crushing it? Answer: Malleability. 383. How many types can it be divided into based on the form of the fuel? Answer: Solid fuel, liquid fuel, gas fuel. 384. What is the main basis for classifying coal? Answer: Volatile matter content and coking property. 385. What is the impact of coal with a low ash melting point on boiler combustion? Answer: Coal with a low ash melting point tends to coking easily. 386. What is the specified lower calorific value for standard coal usage? Answer: 7000 kcal/kg. 387. The ignition temperature of various coals is closely related to the content of what components in the coal? Answer: Volatile matter. 388. There are over thirty chemical elements in coal; which seven can generally be listed? Answer: Carbon, hydrogen, oxygen, nitrogen, sulfur, moisture, ash. 389. At what temperature above does the coal start to self-ignite within one to two days? Answer: 80 degrees. 390. Coal is the main raw material for thermal power plants, and the cost of coal accounts for about 70% of the total cost of power generation. In order to significantly save primary energy resources and improve economic efficiency, what efforts must be intensified? Answer: Coal combustion management. 391. What is the head capacity of the oil unloading pump in our factory? Answer: 70 meters. 392. What is the head of the oil supply pump in our factory? Answer: 353.5 meters. 393. What kind of obvious warning signs must be hung around the oil depot area? Answer: Open flames are strictly prohibited. 394. What regulations must be followed to enter the oil depot area? Answer: Register and hand over the fire source. 395. What are the reasons for the heating of the oil pump housing? Answer: The oil pump has been running idle for too long. 396. What is the capacity of the oil tanks in our plant? Answer: 2,000 cubic meters per unit. 397. What is the designed storage capacity of the dry coal shed in our factory? Answer: 59,000 tons. 398. What is the flow rate of the oil pump in our factory? Answer: 25 cubic meters per hour. 399. What is the flow rate of the oil unloading pump in our factory? Answer: 60 cubic meters per hour. 400. What are the organizational measures for safe work on electrical equipment? Answer: Work ticket system, work permit system, work supervision system, work interruption, transfer, and completion system. 401. What are the technical measures for safe work on electrical equipment? Answer: Power outage, voltage testing, grounding, installation of warning signs, and setting up barriers. 402. Workers must take an exam on electrical safety procedures once a year; those who have been away from electrical work for several months or more due to certain reasons should relearn these procedures Answer: For those over 3 months, it is 403. The moisture content in coal is high; what is the impact on the coal transportation system in winter? Answer: The coal freezes, causing the belt to slip; in severe cases, the belt tears. 404. What is the spontaneous combustion of coal? Answer: When coal oxidizes in air, the heat generated cannot dissipate and accumulates within the pile of coal. As a result, the temperature inside the pile rises continuously until it reaches the ignition point, causing the coal to burn on its own – this phenomenon is known as spontaneous combustion of coal. 405. What does the principle of “three noes” regarding accidents refer to? Answer: Do not let go until the cause of the accident is clear ； Those responsible for the accident, as well as the general public who lack education, will not be spared ； No precaution is left unaddressed. 406. What should be done if someone gets an electric shock? Answer: Turn off the power supply, remove the person who has been electrocuted from the source of electricity, and provide first aid. 407. How to carry out effective flood control, disaster prevention, and moisture protection work in the nuclear power operation field? Answer: 1) Periodically test-operate the sewage pump ； 2) Remove standing water promptly ； 3) Turn on the moisture-proof light inside the electrical cabinet ； 4) Close doors and windows ； 5) Prevent the loss and collapse of coal. 6) Operations of the bucket wheel conveyor should be halted in case of strong winds or heavy rain, and the conveyor should be stopped on the wind-sheltered slope at the southern end of the coal yard ； 7) Ensure that there is always coal stored in the dry coal shed, so that dry coal can be supplied to the silos during prolonged rainy periods. 408. Into which grades is light diesel classified based on its freezing point? Which one does our factory use? Answer: Light diesel is classified into five grades based on freezing point: 0, +20, -10, -20, and -35. Our factory produces #0 light diesel. 409. What are the conditions under which oil tanks need steam heating in winter? Answer: Turn on the steam when the temperature is below 3 degrees, and turn it off when it is above 10 degrees. 410. What are the requirements for using industrial cooling water? Answer: Appropriate amount, unobstructed flow, continuous. 411. What is the temperature at which cooling sprays need to be activated in oil tanks during summer? Answer: 45 degrees, 412. What are the methods to reduce the temperature of a coal pile? Answer: Turning over the pile, loosening the pile, and applying large amounts of water. 413. What are the specific requirements for the “four no’s” in oil areas? Answer: No oil residue, no open flames, no flammable materials, and no weeds. 414. For thermal power plants that do not use a single type of coal, what preparations should be made before the coal is fed into the furnace? Answer: Coal blending work. 415. What should be done in the event of a fire involving electrical equipment? Answer: Immediately cut off the power to the relevant equipment, then extinguish the fire. 416. What devices should be installed at all key working locations of the coal conveyor belt? Answer: Pull-cord switch and alarm bell. 417. What precautions should be taken in the coal transportation system when the volatiles and sulfur content of the coal in use increase? Answer: Explosion-proof work. 418. By how much does the calorific value of bituminous coal decrease after being stored for 1 year? Answer: 1%-10% 419. What interlock relationships exist in the car dumper system’s equipment? Answer? 1. Interlock between the boom of the vehicle dispatcher and the sampler ； 2. Interlock between the vehicle control unit and the main unit ； 3. Interlock between the train pulling machine and the train transfer platform ； 4. Interlock between the workbench and the trolley machine ； 5. Interlock between the vehicle transfer platform and the boom of the vehicle steering machine. 420. What are the characteristics of the traveling mechanism of stacker-reclaimers? Answer: The traveling mechanism consists of two sets of driven trolleys and a driving trolley. The drive trolley is equipped with a two-speed motor; when not performing stacking or reclaiming operations, the speed of the bucket wheel stacker-reclaimer when moving empty is up to 30 m/min, while its speed during such operations is 7 m/min. 421. What are the characteristics of the bucket wheel in a bucket wheel stacker-reclaimer? Answer: The bucket wheel adopts a semi-format structure, and such buckets wheels operate smoothly, with high efficiency and excellent unloading performance in coal yard operations. The edges of the bucket wheel are welded with wear-resistant teeth, which enable coal extraction from frozen layers with a thickness of no more than 100 mm in winter. 422. What is the main function of the bucket wheel luffing mechanism? Answer: The luffing mechanism of the bucket wheel conveyor is primarily used to enable the pitching motion of the cantilever, thereby adjusting the picking height of the bucket wheel during material picking and the drop height of the materials during stacking. 423. How to reduce vibration during the operation of a bucket wheel conveyor? Answer: 1) When the bucket wheel loader is moving quickly, the switching between fast and slow speeds can cause severe vibrations; the travel control should be set to zero directly, and movement should be carried out at a slow speed after the machine has come to a stop. 2) When the bucket wheel conveyor is taking material, if the coal is hard it may cause slight vibrations; in such cases, the method of taking more material in smaller batches or less material in larger batches can be employed depending on the actual situation, to avoid vibrations. 3) When extracting material, if the bucket reaches the ground level, it will cause significant vibration and may damage the bucket; therefore, it is necessary to ensure proper supervision and control the extraction depth, keeping it at least 0.5 meters above the ground surface. 4) Any debris such as large stones and wooden pieces should be removed first before coal is taken. 5) It is prohibited to take hard coal that has been compacted by vehicles. 424. Precautions when the conveyor belt crane’s 380V cable reel does not rotate: Answer: 1) Stop the equipment immediately and contact maintenance personnel to handle it ； 2) Strengthen the monitoring of the bucket wheel crane cable reel while it remains in operation ； 3) When the heavy vehicle moves in the direction of reeling in the cable, close supervision of the cable reel is necessary. It is advisable to move at a low speed; when traveling over long distances, the speed should be changed gradually to avoid inertial sliding due to high speed, which could cause the cable to scatter. 4) When the heavy vehicle starts moving in the direction of cable deployment, it is advisable to start at a low speed, in order to avoid jamming of the 380V cable reel due to high-speed starting, which could result in the breakage of the 380V cable. 425. Briefly describe the advantages and disadvantages of rotary tipplers? Answer: Advantages: high unloading efficiency, low power consumption, large rotation angle ； Disadvantages: Large volume of earthwork is required, with the foundation reaching a depth of 13 M. 426. Briefly describe the structure of the car dumper body? Answer: Rotor, clamping device, backing plate assembly, idler roller device, vibrator, end stop, material guiding device, transmission device, hydraulic system. 427. Concrete weights are installed in the front beam of the turntable rotor; what is their function? Answer: Balance the load on the rotor, thereby reducing the unbalanced torque, lowering the driving power, and reducing the flipping impact. 428. What are the reasons for inaccurate alignment of the car dumper platform? Answer: 1. Coal accumulation at the support seat end. 2. Brake failure. 3. Gear housing displacement. 4. The travel switch disconnects prematurely. 5. Eddy currents are abnormal. 6. Fault in the main control unit. 429. What are the advantages and disadvantages of the three stacking methods used by bucket wheel stackers? Answer: Material piling operations include three methods: rotary piling, fixed-point piling, and traveling piling. The rotary stacking method involves the bucket wheel conveyor stopping at a certain point on the track, with its rotating arm being used to throw coal onto the coal pile. The advantage of this method is that the coal pile has a neat shape, resulting in a high utilization rate of the coal yard. The downside is that the rotation keeps moving, which is not economical. The fixed-point stacking method involves keeping the elevation and horizontal angles of the boom constant while the bucket wheel loader stacks the coal; once the coal pile reaches a certain height, either the front boom is rotated by a certain angle, or the front boom remains stationary while the main frame moves a certain distance. The advantage of this method is: it requires few actions and is relatively economical. The downside is ； The shape of the coal pile is irregular, resulting in a low utilization rate of the coal yard. The walking stacking method involves setting the front arm of the bucket wheel loader at a certain angle and height, then moving the loader while stacking coal; once it reaches the end of the coal storage area, it moves back and continues stacking, with the front arm rotating by a certain angle at the same time. The disadvantage of this method is that the walking motor operates continuously, which is inefficient, and the machine experiences significant vibration. 430. After the maintenance is complete and the equipment is tested, is it allowed to unlock manual start/stop? Answer: What are the total number of positions for the 431 permit and coal blending control levers? Which ones are they respectively? Answer: 3. Programmed setting, manual setting, zero position 432. How does the control room control the on-site coal plow? Answer: 1. The coal plow is at the programmed position ； 2. Which control handle for coal blending mode should be selected? 433. Which machine and which bin corresponds to combustion and operation bin #12 in the centralized control system? Answer: When unloading at #3 Unit, Bin B, location 434, to #B bucket wheel loader, which equipment along the line must be started manually on-site? Answer: For the 7PB disc type magnetic separator 435, during unloading operations, what is the interlock relationship between the tipper and the bucket wheel conveyor with the equipment along the line? Answer: The bucket wheel conveyor is involved in the interlock system, while the dump car is not. What are the two startup methods for belts 436 and #7? Answer: How should it be started during material retrieval operation? Forward start, reverse start. Forward start 437: During normal operation, is it allowed to perform lamp testing from the control room console? Answer: 438 is not allowed. Is it permissible to use the emergency stop button during normal shutdown? Answer: When 439 is not allowed and the machine is in operation, if the emergency stop button is pressed, which device will not shut down immediately? Answer: For the coal crusher 440, when the optical indicator in the control room sends a “slight deviation” signal, will the equipment trip? Will tripping occur if a “re-run deviation” signal is sent? Answer: No. It will be a short-answer question 441: What are the three methods of coal blending? Answer: For low coal levels, priority allocation, sequential allocation, and allocation of the remaining coal are used. The #B bucket elevator transports coal from the B side to bin 6PB. How can the control room carry out interlocked manual start operations? Answer: A. Set the control mode selector lever to the interlock manual position ； B. Press the selection buttons for Bucket 2 pickup, C21, C23, and C28; the indicator light \"Process Valid\" will turn on ； C. Press the “Pre-start” button, and the “Start Allowed” indicator light will turn on ； D. Start the equipment along the line in reverse coal flow order. 443. What are the principles for starting and stopping equipment along the coal transportation route? Answer: Start against the coal flow, stop with the coal flow. 444. #Bucket wheel conveyor from side B to bin 6PB: How to operate the pull rope at 4PB, and which devices will trip as a result? Answer: GZSB, DMF4, 3PB, 7PB, and DLJ2 trip immediately, while SMB shuts down after a delay. 445. How to disable the interlock between the 6PB belt and the 5PB belt? Answer: A. Enter the host computer’s “Function Selection”” ； B. Press “F3” and select “6PB local”” ； C. Press the “ALT+M” button. 446. What are the various operation modes of program control? Answer: 6 types, loading onto the tipper, loading onto #A bucket wheel conveyor, loading onto #B bucket wheel conveyor, unloading from the tipper to #A bucket wheel conveyor, unloading from the tipper to #B bucket wheel conveyor, and coal transfer. 447. Is L7PB involved in the interlock when unloading from Side B into Bucket B? What are the harms? Answer: It does not participate in interlocking; if L7PB is in the lowered position, it will cause coal blockage at the heads of 7PB and 2PB. 448. What is the most important task that the Fuel Operation team must carry out to ensure the stable and safe operation of the centralized control system? Answer: Coal allocation by storage location. 449. What is the significance of achieving centralized control for combustion operation? Answer: A. Increase labor productivity ； B. Reduce labor intensity ； C. Improve the working environment ； D. Improve the safety and reliability of equipment operation. 450. Briefly describe the power-on process of the PLC in the control room? Answer: A. Supply power to the remote station ； B. Supply power to the power cabinet in the control room ； C. Supply power to the communication module. 451. What should be done in case of a fire involving electrical equipment? Answer: The power supply to the relevant equipment should be cut off immediately, followed by extinguishing the fire. 452. What voltage of electrical tools must be used when working inside metal containers? Answer: Below 24V. 453. What type of fire extinguisher should be used to extinguish fires involving potentially live electrical equipment, as well as generators and motors? Answer: Dry chemical fire extinguishers, carbon dioxide fire extinguishers, or 1211 fire extinguishers. 454. What are the main protective devices for electric motors? Answer: Interphase protection, single-phase ground protection, overload protection, low voltage protection. 455. Under what circumstances should the motor be shut down in case of an accident? Answer: 1. In the event of a personal accident that requires the immediate shutdown of the motor ； 2. The machinery driven by the motor is damaged to a dangerous extent ； 3. The electric motor is on fire and smoking. 456. What should be done if someone gets an electric shock? Answer: When someone is found to be electrocuted, the power supply should be cut off immediately to free the victim from the electric current, and first aid should be provided. When working at heights, care must be taken to prevent falls during rescue operations. 457. What are the common faults of electric motors? Answer: Motor vibration, motor overheating, motor operating on two phases, increased motor temperature, vibration, humming, etc. 458. What are the continuous magnetic strength levels of belt-type iron removers? Answer: 100% and 25% – these are the two options for 459. What type of coal crusher does our factory use? Answer: 460 for ring coal crushers. What are the two operating modes of belt-type iron removers? Answer: What type is the belt tensioning device for #8 in our plant, for normal operation and forced operation modes 461? Answer: Small vehicle tensioning device 462. What is the rotation speed of the coal conveying belt in our factory? Answer: 2.5 M/S463. What are the three common types of coal conveyor belt tensioning devices? Answer: Screw, trolley, weight 464. What are the two types of buffer idlers in a belt conveyor? Answer: Rubber, spring 465. What determines the width of a belt conveyor? Answer: Transport volume and speed 466. What is the driving principle of a belt conveyor? Answer: Principle of friction drive 467. What are the main components of a belt conveyor? Answer: Tape, upper and lower idlers, drum, tensioning device, motor, reducer, and protection devices. 468. What is the inclination angle of belt #4 in our factory? Answer: 16 degrees 469. Generally, what is the maximum inclination allowed for coal conveyor belts at horizontal levels? Answer: 18 degrees, 470. Parallel idlers are generally long idlers; what is their main purpose? Answer: Lower idler 471. What is the allowable temperature for the reducer’s operating environment? Answer: -40 degrees to 45 degrees. 472. What is the maximum allowable deviation of the conveyor belt during operation? Answer: 473. At what angle above a certain degree should a braking device be installed on a belt conveyor for the idler rollers and the edges of the drum? Answer: 4 degrees, 474. After the coal crusher is started, the mechanical part struggles to rotate or does not rotate at all, and the current remains high without dropping; what is the reason? Answer: There are debris in the machine, and coal has blocked chamber 475 of the coal crusher. Why is the current of the coal crusher fluctuating? Answer: Uneven feeding 476. What are the reasons for intense vibration of the coal crusher, a sudden increase in current, and severe noise? Answer: Large pieces of coal or iron enter the coal crusher 477. What are the different types of iron removers? Answer: Suspended type, drum type, belt type 478. What is the maximum allowable temperature for the bearings of the operating equipment? Answer: 65 degrees, 479. What is the maximum allowable temperature for the reducer of the operating equipment? Answer: 60 degrees, 480. What is the maximum allowable temperature for the motor of the operating equipment? Answer: 80 degrees, 481. The belt stops operating under full load; once the motor has cooled down, how many times is it allowed to start while under load? Answer: 2 times, 482. What is the interval required between consecutive starts of the belt? Answer: 5 minutes and 483. The belt failed to start under load 2 times – what should be done? Answer: Reduce the load on the belt, and restart the motor after it has cooled down. 484. Under what circumstances should the coal distributor and the three-way dampers be switched during operation? Answer: No load, no sticky coal, 485. What changes in the coal crusher should be monitored while it is in operation? Answer: Ammeter 486. What should be the maximum bearing temperature when the coal crusher is in operation? Answer: 75 degrees, 487. What should be the maximum allowable vibration of the machine body when the coal crusher is in operation? Answer: 0.15MM488. What is the allowable vibration level of the motor driving the coal crusher? Answer: 0.1MM489. What are the seven protections for belt conveyors? Answer: Polar deviation, coal flow signal, slip protection, speed switch, two-way emergency pull cord switch, coal blockage signal, longitudinal tear protection. 490. What is the output capacity of the roller screen in our factory? Answer: 1500T/H491. What is the particle size of the undersize material from our factory’s roller screen? Answer: ≤40MM492. Why is an interlock device required in the coal conveying belt system? Answer: 1. To reduce the number of starts and stops of the system conveyor ； 2. Ensure that the coal conveyor belts in the system start and stop in sequence ； 3. When a critical device in the system fails, the system stops automatically. 493. What are the common reasons for belt deviation when the coal conveyor belt is in operation? Answer: 1. Coal sticking to the drum ； 2. The tape connection is not proper ； 3. Improper coal discharge from the coal discharge pipe ； 4. The guide chute is too tight or misaligned. 494. What is the impact of dust on coal conveying equipment? Answer: 1. Dust adheres to the equipment’s casing, preventing heat dissipation and reducing the equipment’s service life ； 2. Dust adheres to electrical connections, causing electrical faults ； 3. Dust adheres to the rotating parts, affecting bearing lubrication. 495. Why is it generally not allowed to start a belt conveyor under heavy load? Answer: This is because during start-up with no load, especially on inclined conveyors, the instantaneous current required for start-up **exceeds several times the current limit allowed by the motor. If the conveyor starts under heavy load, the motor may overheat and get damaged as a result; therefore, starting a conveyor under heavy load is generally not permitted. 496. What is the reason why the motor does not rotate when a belt conveyor starts operating? Answer: 1. No power supply ； 2. Insurance fuse blown ； 3. The control device is faulty. 497. What are the advantages and disadvantages of roller screens? Answer: Advantages: Simple structure, stable operation, reliable performance, screening efficiency of 80%, low maintenance requirements, and easy installation ； Disadvantages: Excessive moisture can cause coal clogging, it makes a lot of noise during operation, and its production capacity is low. 498. What is the working principle of a ring coal crusher? Answer: A high-speed rotating rotor is used to drive the ring hammers to impact and crush the material; the impacted material is then subjected to compression, shearing, and grinding actions between the ring hammers, the crushing plates, and the screening plates, thereby achieving the desired particle size. 499. What are the high calorific value and low calorific value of coal? Answer: The heat released when 1 kg of coal burns completely, with the water in the combustion products remaining in liquid form, is known as the high calorific value. The calorific value when the water in the combustion products remains in a vapor state is the lower calorific value. 500. What is the impact of increased moisture content in coal on the coal transportation system? Answer: 1) Excessive moisture in coal can cause coal to stick to and clog the coal transportation equipment; in severe cases, this can prevent coal from being transported. 2) High moisture content in coal leads to spontaneous flow during transportation, making it difficult to feed coal into the systems. In extremely cold winters, especially in the northern regions, the coal can freeze, thereby affecting its unloading and transportation. 3) An increase in moisture content in coal reduces its lower calorific value.