Questions for Advanced Boiler Operators

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Questions for Advanced Boiler Operators I. Multiple-choice Questions 1. The calorific value of standard coal is (). A.20934KJ ； B.25120.8KJ ； C.29271.2KJ ； D.12560.4KJ。 2. The main reason for the low efficiency of thermal power plants is (). A. Low boiler efficiency ； B. Thermal loss in turbine exhaust steam ； C. Generator heat loss ； D. Mechanical losses of the turbine: 3. The boiler itself consists of the steam drum and ( ). A. Economizer ； B. Air preheater ； C. Furnace ； D. Superheater. 4. The flue gases emitted by thermal power plants cause air pollution, and their main pollutant is (). A. Sulfur dioxide ； B. Dust ； C. Nitrogen oxides ； D. Trace heavy metals. 5. During operation, the fan inevitably experiences fluid (), as well as friction losses in its own transmission components. A. Friction ； B. Impact ； C. Leakage ； D. Friction, impact, leakage. 6. The melting point of boiler ash is mainly related to the ( ) of the ash. A. Components ； B. Physical form ； C. Hardness ； D. Grindability 7. Low-temperature corrosion is （） corrosion. A. Alkaline ； B. Acidity ； C. Neutral ； D. Oxygen. 8. When the amount of air in the furnace is insufficient, the coal combustion flame is (). A. White ； B. Dark red ； C. Orange ； D. Red. 9. The viscosity of oil increases as the temperature rises (). A. Unchanged ； B. Reduce ； C. Increase ； D. Coagulation. 10. A failure in the coal supply to the pulverizing system can easily lead to (). A. Increase in steam pressure and steam temperature ； B. Decrease in steam pressure and temperature ； C. No impact at all ； D. The drum water level rises suddenly. 11. The main factor affecting powder ignition is (). A. Volatiles ； B. Carbon content ； C. Ash content ； D. Oxygen. 12. Too fine coal powder can cause (). A. Increased power consumption of the coal grinder ； B. Reduction in coal mill power consumption ； C.q4 increased ； D. The exhaust temperature decreases. 13. The greater the circulation ratio of the boiler water cycle, the more intense the water circulation (). A. The more dangerous ； B. The more reliable ； C. No impact ； D. Increased resistance. 14. An air preheater uses the heat from the flue gases at the back of the boiler to heat the () used in boiler combustion. A. Water supply ； B. Air ； C. Combustion ； D. Fuel. 15. As the boiler pressure gradually increases, its cycle rate (). A. Unchanged ； B. Gradually getting larger ； C. Gradually getting smaller ； D. Sudden increase. 16. Within the allowable range, maintaining as high a steam temperature and steam pressure as possible results in (). A. Decrease in boiler thermal efficiency ； B. Improvement in boiler thermal efficiency ； C. Improvement in cyclic thermal efficiency ； D. Improvement in turbine efficiency. 17. An increase in the moisture content in coal will result in an increase in the heat absorbed by the convective superheater (). A. Increase ； B. Reduce ； C. Unchanged ； D. Decreases in a logarithmic relationship. 18. When the excess air coefficient remains constant, changes in load result in corresponding changes in boiler efficiency; below the economic load, as the boiler load increases, the efficiency (). A. Unchanged ； B. Reduce ； C. Increase ； D. Decreases in a logarithmic relationship. 19. With constant external load, when combustion weakens, the drum water level (). A. Rising ； B. Decline ； C. First decline then rise ； D. First rises and then falls. 20. The main purpose of sliding parameter shutdown is (). A. Generating electricity using boiler waste heat ； B. Uniformly reducing parameters to extend the unit’s lifespan ； C. Preventing the turbine from overspeeding ； D. Reducing the temperature of the turbine casing facilitates earlier inspection. 21. During operation, a drum boiler should be shut down urgently when (). A. Reheater tube rupture ； B. Superheater tube rupture ； C. All level gauges are damaged ； D. Economizer leakage. 22. As the operating hours increase, the main reason for the gradual increase in fan vibration is generally (). A. Bearing wear ； B. Abnormal air intake ； C. Abnormal air outlet ； D. Wear of the fan impeller. 23. Charged electrical equipment, as well as generators and motors, etc., should be extinguished using (). A. Dry chemical fire extinguishers, carbon dioxide fire extinguishers, or 1211 fire extinguishers ； B. Water ； C. Foam ； D. Dry sand. 24. When someone is found to have been electrocuted, the first thing to do is to immediately (). A. Cut off the power supply ； B. Pull the person who has been electrocuted away from the power source ； C. Contact the medical department ； D. Perform first aid for breathing. 25. The characteristic pattern of damage caused by corrosion of the heating surfaces due to prolonged insufficient dissolved oxygen in the feed water is ( ) A. Large-scale uniform corrosion ； B. Flaky corrosion ； C. Pitting corrosion. 26. When the pressure rise rate of the boiler remains constant, the mechanical stress generated in the steam drum during the later stage of pressure rise is ( ) compared to the earlier stage. A. Large in the previous stage ； B. Small in the later stage ； C. The preceding and following stages are equal ； D. Larger in the later stage. 27. With constant external load, when combustion weakens, the drum water level (). A. Rising ； B. Decline ； C. First decline then rise ； D. First rises and then falls. 28. The purpose of passivation treatment after acid cleaning of the heated surfaces is (). A. Form a dense layer of magnetic iron oxide protective film on the metal surface ； B. Smooth the metal surface ； C. Form a wear-resistant protective layer on the metal surface ； D. Rinse off the residual iron shavings from the metal surface. 29. The main purpose of sliding parameter shutdown is (). A. Generating electricity using waste heat from boilers ； B. Uniformly reducing parameters to extend the unit’s lifespan ； C. Preventing the turbine from overspeeding ； D. Reducing the temperature of the turbine casing facilitates earlier inspection. 30. After the boiler’s “MFT” operates, the interlock () trips. A. Blower ； B. Exhaust fan ； C. Air preheater ； D. Primary fan. 31. The total steam discharge capacity of the safety valve should be ( ) the maximum continuous evaporation rate of the boiler. A. Greater than ； B. Less than ； C. equals ； D. Close. 32. In the event of a leak in the water wall, economizer, reheater, or header, it is necessary to (). A. Emergency shutdown of the furnace ； B. Apply for shutdown of the furnace ； C. Maintain operation ； D. Shutdown for holidays. 33. Open the air valve when the main steam pressure of the boiler drops to (). A.0.5Mpa ； B.1Mpa ； C.0.2Mpa ； D.3.5Mpa。 34. When the quality of boiler feedwater, furnace water, or steam exceeds the standards and cannot be restored to normal despite various adjustments, it is necessary to (). A. Emergency shutdown of the furnace ； B. Apply for shutdown of the furnace ； C. Chemical treatment ； D. Continue running. 35. Start the exhaust fan for ventilation and cooling () hours after a normal shutdown. A.4～6 ； B.18 ； C.24 ； D.168。 36. The operating method for the series-connected drain valve is (). A. Open the secondary door first and then the primary door; reverse the order when closing ； B. Determine it based on whether it is convenient to operate ； C. Open the second door after opening the first one; do the opposite when closing ； D. Determined by the operator based on the load level. 37. The set values for the control safety valve and the working safety valve in high-pressure boilers are ( ) times the rated pressure. A.1.05/1.08 ； B.1.02/1.05 ； C.1.10/1.10 ； D.1.25/1.5。 38. The sequence for calibrating the safety door of a boiler is (). A. In order of actuation pressure, from bottom to top ； B. In order of actuation pressure, from high to low ； C. Start with the easy tasks first ； D. Start with the difficult tasks and move on to the easier ones. 39. The auxiliary machinery in thermal power plants that consumes the most electricity is (). A. Feed water pump ； B. Blower ； C. Circulation pump ； D. Coal grinder. 40. The pressure drop rate during the shutdown process shall not exceed ( ) per minute. A.0.05MPa ； B.0.1MPa ； C.0.15MPa ； D.0.2MPa ； 41. Before entering the drum, the staff should check the temperature inside it; it should generally not exceed (), and entry is only permitted when there is good ventilation. A.40℃ ； B.50℃ ； C.60℃ ； D. 55°C. 42. The largest cost item in thermal power plants is (). A. Fuel cost ； B. Wages ； C. Major and minor repair costs ； D. Equipment depreciation expense. 43. After shutting down a pulverized coal furnace, the rated air volume should be maintained at over 30% to facilitate ventilation () for furnace purging. A.5min ； B.10min ； C.15min ； D.20min。 44. During normal operation of the boiler, it is advisable to keep the opening degree of the feedwater control valve at (). A. 70%～80% ； B. 40%～70% ； C. 50%–100% ； D. 80%–90%. 45. The total steam discharge capacity of the safety valves must be greater than the boiler’s maximum continuous evaporation rate, and when all the safety valves on the boiler and superheater are opened, the steam pressure inside the drum shall not exceed () times the design pressure. A.1.02 ； B.1.05 ； C.1.10 ； D.1.25 ； 46. In the boiler three-element feedwater automatic control system, () is the main signal. A. Drum water level ； B. Water supply flow rate ； C. Steam flow rate ； D. Water supply pressure. 47. In the regulation of the superheated steam temperature in a boiler, the controlled variable is (). A. Superheater outlet temperature ； B. Cooling water volume ； C. Opening degree of the cooling water control valve ； D. Water supply pressure. 48. The boiler body consists of the steam drum and ( ) two parts. A. Economizer ； B. Air preheater ； C. Furnace ； D. Superheater. 49. The flue gases emitted by thermal power plants cause air pollution, and their main pollutant is (). A. Sulfur dioxide ； B. Dust ； C. Nitrogen oxides ； D. Trace heavy metals. 50. The main characteristics during the coal powder ignition preparation stage are (). A. Release heat ； B. Analyze volatile matter ； C. The combustion chemical reaction occurs rapidly ； D. Not affected by external conditions. 51. When the amount of air in the furnace is insufficient, the coal combustion flame is (). A. White ； B. Dark red ； C. Orange ； D. Red. 52. To prevent spontaneous combustion in the coal powder bin behind the furnace, it is necessary to (). A. Open the baffle of the coal powder bin for ventilation ； B. Close all baffles and moisture absorption tubes ； C. Open the valve of the moisture absorption tube to maintain negative pressure in the powder bin ； D. Use steam for fire suppression. 53. The main measures to prevent explosions in the pulverized coal system are (). A. Eliminate dust accumulation in the system, (), maintain a normal flow rate of the air-powder mixture, remove sources of ignition, and keep the system temperature within the specified range ； B. Monitor carefully and make fine adjustments ； C. Preventing interruptions in coal supply during operation ； D. Deploy a steam fire extinguishing system. 54. The main factor affecting powder ignition is (). A. Volatiles ； B. Carbon content ； C. Ash content ； D. Oxygen. II. True or False Questions 1. Absolute pressure is the true pressure of a fluid, that is, p = pg + pa. ( ) 2. In thermal power plants, the boiler is the device used to produce steam; the capacity of the boiler is referred to as its evaporation rate, which is measured in t/h. （）3. When the amount of fuel is the same, the required air volume for burning oil and coal powder is also the same. ( )4. Coal elemental analysis is a term that refers to the determination of elements such as carbon, hydrogen, oxygen, nitrogen, and sulfur in coal. （）5. Coal has a low ash melting point, so it does not easily cause overheating of the water wall and superheater, leading to slag formation. （）6. Bituminous coal is characterized by a high volatile matter content, making it easy to burn and less prone to coking. （）7. The steam temperature characteristic of the boiler convective superheater is that it decreases as the load increases. （）8. The reducing gases generated by the incomplete combustion of coal can exacerbate coking on the heating surfaces of the boiler. ( )9. The automatic control systems of thermal power plants can be classified into the following three types based on their overall structure: distributed control systems, centralized control systems, and hierarchical control systems. （）10. To prevent wear of the mill bearings, it is necessary to ensure that oil dripping from the large bearings is normal before starting up, and to activate the low oil pressure protection. （）11. The processing capacity of the steel ball coal grinder increases in direct proportion to the amount of steel balls loaded. ( )12. Recirculated air plays a role in drying within the coal grinding system. ( )13. The methods for dealing with a clogged coarse powder separator include: clearing the powder return pipe, checking the air lock or shutting down the powder production system, and removing debris inside the separator. ( )14. There are two methods for calculating the thermal efficiency of boilers: positive balance and negative balance. ( )15. Among all the losses in a boiler, heat loss is the greatest. （）16. After the boiler stops receiving water supply, the economizer recirculation valve should be opened; when the boiler is supplied with water continuously, the economizer recirculation valve should be closed. ( )17. 30 minutes after shutdown, open the superheater drain valve to cool the superheater. （）18. When a boiler is severely overfilled with water, the steam temperature drops rapidly, and water hammer can occur in the steam pipes. ( )19. At the beginning of ignition in a natural circulation boiler, it is necessary to increase the water discharge from the lower header of the water wall; this is done to promote water circulation, ensure even heating of the heated surfaces, and thereby reduce the temperature difference across the drum wall. （）20. The steam pressure requirements for starting and paralleling boilers connected to the main pipe are as follows: for medium-pressure boilers, it should be 0.05–0.1 MPa lower than that of the main pipe; for high-pressure boilers, it is generally 0.2–0.3 MPa lower, in order to prevent a sudden drop in steam pressure after paralleling. （） III. Multiple-choice questions 1. Boiler manufacturers should meet the following conditions ( ) A. Possess corporate legal status or have obtained legitimate registration in their location B. Have production facilities, processing equipment, technical expertise, and testing methods suitable for manufacturing the products C. Have established a quality assurance system that functions effectively D. Ensure that the safety performance of their products meets the basic requirements of **safety technical specifications 2. The coal transportation system refers to the process of transporting coal from the coal storage area to the coal hopper in front of the furnace, which includes tasks such as the handling of coal and its measurement. A. Transshipment B. Crushing C. Screening D. Magnetic separation 3. Determining the coal transportation method for the boiler room depends on many factors. They are primarily determined based on (), through technical and economic comparisons. A. The amount of coal transported B. Topographical conditions C. Coal supply situation D. Natural conditions. 4. The mechanical ventilation methods used in boilers can be divided into ( ) three types: A. Natural ventilation B. Negative pressure ventilation C. Positive pressure ventilation D. Balanced ventilation. 5. The volume of air blown by the fan can be adjusted through methods such as ( ). A. Changing the opening degree of the inlet gate or baffle. B. Changing the rotational speed of the fan impeller. C. Changing the opening degree of the guide vane blades. D. Changing the opening degree of the outlet gate or baffle. 6. The accumulation of ash on the water wall of a boiler furnace has the following effects on the boiler (). A. Reduced heat absorption in the furnace B. Lower flue gas temperature C. Decreased thermal efficiency of the boiler D. Increased superheated steam temperature 7. When performing flue gas analysis using an Oxytype flue gas analyzer, the gases that are absorbed include ( ) A. RO2 B. O2 C. Air D. CO 8. The pressure-bearing components of the boiler itself mainly include ( ) and so on. A. Water wall B. Convection tube bank C. Header D. Drum 9. The heat absorption of the convection tube bank is related to ( ). A. Flue gas velocity B. Type of fuel C. Arrangement of tubes D. Method of flue gas scouring 10. Commonly used devices for rough separation of steam and water in industrial boilers include ( ) and submersed orifice plates, etc. A. Wave plate B. Volute separator C. Inlet baffle D. Cyclone separator 11. Based on the relative flow direction of flue gas and steam, convective superheaters can be classified into (). A. Downstream B. Upstream C. Double upstream D. Mixed flow 12. Air preheaters come in three types: ( ) and rotary types. A. Boiling type B. Tubular type C. Plate type D. Non-boiling type 13. In coal-fired boilers, the factors that cause wear on the rear heating surfaces include ( ) A. The arrangement pattern of the tubes B. The properties of ash particles C. The flow velocity of flue gas D. The concentration of fly ash 14. The main functions of the boiler furnace wall are ( ) A. Insulation B. Raising the air temperature C. Sealing D. Providing shape or forming channels 15. Boilers under any of the following conditions require a hydrostatic test: ( ) A. It has been 6 years since the last hydrostatic test was conducted B. Boilers whose pressure-bearing components have undergone major repairs or modifications C. Newly installed or relocated boilers D. Boilers that have been out of service for more than a year and need to be put back into operation 16. The criteria for passing a hydrostatic test are ( ) A. No water droplets or mist on the metal walls and welds of the pressure-bearing components B. No water droplets dripping from the expansion joints when the pressure is reduced to the operating level C. When water supply is stopped at the operating pressure, the pressure drop within 5 minutes should be within 0.5 MPa D. No residual deformation after the hydrostatic test 17. For boilers with a rated steam pressure of P≤0.8 MPa, the starting pressure for the control safety valve is ( ), and the starting pressure for the operating safety valve is ( ) A. Operating pressure + 0.03 MPa B. Operating pressure + 0.05 MPa C. 1.04 times the operating pressure D. 1.06 times the operating pressure 18. Factors that affect the rate of change in steam pressure include ( ). A. Speed of load variation B. Heat storage capacity of the boiler itself C. Thermal inertia of the boiler’s combustion equipment D. Variation in boiler water level. 19. The main factors affecting the temperature changes of superheated steam include factors such as the temperature of the desuperheating water. A. Temperature of the flue gas B. Flow rate of the flue gas C. Flow rate of saturated steam D. Temperature of saturated steam 20. The symptoms of air leakage in an air preheater include ( ) A. An increase in the current of the supply fan, along with a decrease in the wind pressure at the inlet and outlet of the preheater B. An increase in the current of the exhaust fan C. An increase in the exhaust gas temperature D. A decrease in the exhaust gas temperature IV. Short answer questions 1. What are the four factors necessary for complete combustion? 2. What is the heat source for the ignition of the coal powder gas stream? What are the factors that affect the ignition of coal powder airflow? 3. What is the water cycle? What are the types of water cycles? 4. What is the impact of impurities in steam on the safe operation of boiler and turbine equipment? 5. What are the factors that affect high wall temperatures in superheater tubes? 6. What parameters are generally tested during the testing of the powder production system? 7. Why does coal powder flow by itself? 8. What is the function of a powder exhaust machine? 9. Why does the pressure rise rate of the boiler start slowly and then speed up during ignition? 10. What are the conditions for connecting a boiler to the steam system? V. Calculation problems 1. The excess air coefficient at the outlet of a boiler’s furnace is 1.2. What is the oxygen content in the flue gases at this point? 2. If the continuous blowdown rate of a certain boiler is P=1%, what is the blowdown volume Dpw when the boiler’s output is 610 t/h? 3. During a reverse balance thermal test of a boiler, the test results were q2=5.8%, q3=0.15%, q4=2.2%, q5=0.4%, q6=0. Determine the reverse balance efficiency of the boiler. 4. The gauge pressure reading on the boiler drum pressure gauge is 9.604 MPa, and the gauge pressure reading on the atmospheric pressure gauge is 101.7 kPa. Determine the absolute pressure of the fluid inside the drum.