Coal gasification information

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) Shell Carbon monoxide changes with the oxygen-to-coal ratio. As the oxygen-to-coal ratio increases, more coal will undergo combustion reactions, the heat release will increase, and the temperature of the gasifier will rise, providing more heat for the endothermic gasification reaction, which is beneficial to the gasification reaction. Therefore, the carbon conversion rate, cold gas efficiency and gas production increase, while CO2, specific oxygen consumption and specific coal consumption decrease. As the oxygen-to-coal ratio further increases, the carbon conversion rate does not increase much. At the same time, due to excess oxygen entering the gasifier, CO2 increases, which reduces the cold gas efficiency and gas production rate, and increases the specific oxygen consumption and specific coal consumption. Therefore, the oxygen-to-coal ratio should have an optimal value. It is generally believed that the atomic ratio of oxygen to carbon is around 1.0. The C element must be balanced. Putting aside the factor of carbon conversion rate, the trend of CO concentration and CO2 should be opposite. If you consider the issue of C conversion rate, the situation is slightly different, but the general trend remains unchanged. Generally speaking, the amount of CO generated changes with the oxygen-to-coal ratio: it first increases and then decreases, with a maximum value appearing in the middle. The coal-water slurry gasification reaction is slightly different, because the shift reaction also has a prominent impact on the gas composition. An increase in the amount of oxygen will lead to an increase in the proportion of carbon oxidation to CO2, but an increase in temperature will lead to a decrease in the shift reaction. The specific situation also requires detailed analysis, but it feels that the overall trend should be the same. 2) What interlocks should be set to trip the Texaco gasifier when the liquid level is low? Should I set up a low-flow and low-jump chain for the chilled water? Should the water washing tower be equipped with a low-liquid-level trip interlock? Set the quench chamber liquid level to 15% interlocking (this value is determined through discussions between the design institute and GE. The gasifier size is 3200mm * 3800mm). It is necessary to set up a chain for quenching water. As for the carbon washing tower liquid level chain, it is meaningless and is completely unnecessary. There are two out of three interlocks for low liquid level in the gasifier. This interlock should be turned on during operation! To stay safe! There is no need to set up a low-flow trip interlock for the quench water, because the gasifier system has a low-flow quench water interlock. When the quench water is low, the accidental quench water replenishment valve will be fully opened! There is no need to set up a jump chain for the water washing tower, there is enough time to deal with it! The gasifier liquid level must be maintained during normal operation. It is true that these two valves will automatically close when the liquid level is low, but the liquid level is only a little higher than the trip value. As for the low liquid level in the gasifier, the two valves will be closed in series, mainly to prevent gas blow-by due to low liquid level, not to protect the liquid level in the gasifier. If there is a problem with the quench water pump, the backup pump will start automatically. The deaeration water pump directly supplies water to the gasifier manually. This is a last resort and is generally not used. In addition, during operation, as long as there is no misoperation or a problem with the lock bucket program control system, the gasifier liquid level cannot reach the trip value instantly. If the gasifier liquid level is low due to water problems, I support releasing the quench chamber liquid level chain to assist in processing. 3) What common problems will occur during the operation of the Texaco gasifier quench ring, and how to perform inspection and maintenance? Chill ring blockage is a common problem, which is mainly manifested as a decrease in the flow rate of the quench water and an increase in the pressure difference between the quench water and the gasifier. When the quench water flow rate drops to a certain level, the machine must stop and clean the quench ring. Process measures: a) Strengthen the control of gray water quality and try to drain and replenish fresh water according to design requirements. b) Test and select appropriate gray water dispersion stabilizer under high temperature and high pressure to effectively prevent scaling and corrosion of the quench ring and the quench ring water inlet pipe, so as to avoid reducing the amount of quench water due to scale blockage and abrading the inner wall of the quench ring pipe due to excessive ash. c) Control the number of consecutive bets, try not to make consecutive bets, and the operation period should not be too long. d) Optimize operations to avoid dust and water in the process gas and deterioration of the water quality of the water washing tower. 4) The reason for the high temperature of the Texaco gasifier support plate. The uneven distribution of the quench water film can cause slagging in the downcomer and block it. Slagging at the slag port also causes gas to be suffocated in the gasifier, which can easily cause the temperature of the support plate to be high, and will also increase the overall temperature of the gasifier. Therefore, in terms of control, try to keep the temperature of the gasifier stable and suitable for the ash melting point of this coal. After the temperature of the gasifier support plate is high, reduce the load while maintaining system stability, and pay attention to the temperature of the furnace. Do not hold the gas for too long, which will easily cause the gasifier to bulge, which will have a great impact on the future operation of the equipment. Reasons for the high temperature of the support plate: a. The refractory bricks at the cone bottom of the gasification furnace are thinned, and the thermal resistance is reduced, allowing a large amount of heat to be transferred to the support plate, causing the temperature to rise. b. Cracks appear on the support plate. Gas from the gasifier passes through the cracks. c. The thermocouple is covered with a large amount of dust and the heat cannot be taken away by the rising airflow. d. The pressure in the gasification furnace increases or fluctuates, causing gas to flow through the cone bottom bricks. The main reasons for the high temperature of the Texaco gasifier support plate are:: a. The fire zone moves downwards ； b. The gap between the cone bricks is large, or the service life has expired, or the ablation is serious due to quality reasons. ； c. The burner nozzle sprays partially, causing the cone bricks to be partially burned and the temperature to be high. ； d. The water distribution in the quench ring is uneven, or there are local dry areas. ； e. Coal quality changes, operators do not respond in time, and operate improperly. 5) What issues should be paid attention to when using the German-style three-flow burner? How long can you use it for the longest time? The burner of the Lunan Fertilizer Plant has been running for a maximum of 151 days, and you will be very nervous in the later period! The operation cycle of Lunan's burners and refractory bricks is relatively long. There are many reasons. Of course, it is inseparable from the operating level of Lunan's workers and the technical management level of its leaders. However, it must be mentioned that the operating pressure of Lunan's gasifier is only 2.7MPa, and Lunan's coal blending is relatively good, and the operating cycle also depends to a large extent on the coal type. The 151 days of operation of Luhua's burners were completely within the plan. During the early stage of shutdown and maintenance, all indicators of the gasifier were normal, the atomization effect of the burners was normal, and there were no obvious abnormalities in the combustibles in the slag. Burners with longer operating times are now being researched. Pay attention when operating the gasifier: a. It is strictly forbidden to cut off the cooling water. b. Minimize the number of starts and stops. c. Try to use coal with a large grindability index. d. The temperature of the gasifier should not be too high. Texaco burner is the core equipment of Texaco coal gasification process. Generally, the atomization effect is good in the early stage of operation. The gas composition is stable. System working conditions are stable ； In the later stages of operation, the nozzle head deforms and the atomization effect is not good. At this time, the gas composition changes greatly and the effective gas composition decreases. Especially when partial spray occurs, the local temperature will be too high and the thermocouple will be burned out. In serious cases. Blow-by occurs, causing the furnace wall to overheat. To maximize the burner operating cycle, you need to pay attention to the following points:: a. Coal quality and coal slurry quality are the main factors that affect the life of the burner. The ash melting point of coal should not exceed 1300°C, and the coal slurry concentration should be controlled at 55-56%. b. Control the gasification temperature as low as possible to effectively improve its operating cycle. Generally, it should be controlled below 1350°C. c. When the amount of coal input into the system changes significantly, the coal/oxygen ratio must be adjusted to a suitable range in advance to resolutely prevent temperature rise. 6) What are the causes and solutions for Texaco gasification downcomer burnout? The quench ring is clogged, the water distribution in the downcomer is uneven, and a water film of a certain thickness cannot be formed on the inside of the downcomer to protect the downcomer, causing burnout. The main reason is that the furnace temperature is too high, causing the quench ring to become clogged. The main reasons for high furnace temperature are as follows:: a. The oxygen-to-coal ratio increases, that is, the oxygen supply increases unilaterally. b. Coal quality is unstable, resulting in lower ash melting point ； Or the amount of flux added is insufficient or less, resulting in a lower ash melting point. c. There is a problem in each quench water supply channel, resulting in insufficient quench water volume. The reasons why the downcomer burns through are:: a. The quench water flow rate is lower than the process index or the quench water is unevenly distributed on the quench ring, causing partial water outage in the downcomer. b. Quality problems in some welding points. c. Wrong material selection of the downcomer. d. Instability during the production process. The liquid level control of the gasifier is too low, causing the downcomer to be unstable. Through observation and analysis in the furnace and comprehensive comparison based on the parameters during the operation period, it is believed that the fundamental reason is the formation of dry zone.: First, the main reason is the small amount of water in the quench ring ； Second, the heat load of the gasifier is too large, which destroys the water film in the downcomer, causing slag to hang. ； Third, the burner sprays in a biased direction, and the fire zone moves downwards greatly, which directly tears the water film on the downcomer, causing slag to hang. ； Fourth, the performance of ash and slag is unstable. 7) The slag port of the German-style ancient gasification furnace is blocked. If the slag port is blocked, you must first find out why it is blocked. Generally, it is rarely blocked during driving unless the temperature is very low and the load is added very slowly, which may cause unstable coal slurry flow. Normally, the slag port is blocked because your temperature fluctuates greatly. The CH4 control is too high and cannot control 5000PPM. Generally, the maximum is 3000PPM, but the time cannot be too long, because this agrees with the blocking of the slag port. If it is blocked, you can increase the temperature but the speed will not be If it is too fast, it should be about 10 degrees in half an hour. The central oxygen should be controlled at about 20 percent. You must always observe the PDI1214, which is the pressure difference, but sometimes you can't trust it too much. You should also look at the furnace pressure and the syngas outlet pressure to calculate the pressure difference yourself. This is more accurate. Generally, the slag opening can be melted if the blockage is not severe. The most important thing is that the temperature should not fluctuate greatly, and it depends on the ash melting point. The proportion of limestone should also be matched to achieve the ash melting point. On the one hand, it is caused by improper operating temperature of the gasifier. The principle of gasifier temperature control is to maintain a low temperature as much as possible while ensuring liquid slag discharge. However, if the temperature is controlled too low, the fluidity of the slag will become poor and more will accumulate at the tapered slag mouth, resulting in a smaller slag mouth. The residence time of the gas in the combustion chamber will increase significantly, and the composition of the gas will change accordingly. On the other hand, it is caused by the increased opening angle of the Texaco burner mouth. The opening angle of the Texaco burner has strict design dimensions. After running for a long time, the burner wears, the opening angle increases, and the combustion is not good. The ash brought to the furnace wall under high pressure will increase. When the slag accumulates to a certain extent, under the dual influence of gravity and gas impact, the accumulated slag flows along the furnace wall to the slag opening. The slag accumulates at the slag opening, and the slag opening becomes smaller. When the slag mouth is not smooth, the oxygen-to-coal ratio should be adjusted in time, the furnace temperature should be increased, and the slag should be melted slowly. This process cannot be too hasty, and the principle of adding oxygen in small amounts at multiple times must be strictly followed to avoid causing the slag opening to shrink again, because the amount of slag will increase at this time. At the same time, pay attention to the changing trend of the furnace temperature. If discovered in time, by increasing the oxygen-to-coal ratio, it can usually be restored within 8 hours. When the slag mouth returns to normal and the gas composition is relatively stable, the oxygen-to-coal ratio can be appropriately reduced. Observe for a few more hours to confirm that there are no signs of recurrence, and return to normal operating temperature operation. How to judge whether the slag port is blocked: 1． Look at the pressure difference of the gasifier and the outlet pressure of the scrubber and calculate it yourself. If the pressure difference is large, it means there will be some blockage. 2. Looking at PDI1214, this is not very accurate. 3. Check the liquid level of the gasifier. If it is blocked, the liquid level will fluctuate greatly. 4. The synthesis gas gas analysis result shows less CO and more CO2. CH4 fluctuates too much 5. To see the scum, go and look under the lock bucket. 8) What are the causes, hazards and solutions to the phenomenon of water in the process gas at the outlet of the Texaco gasification scrubber? There are generally two reasons for the water in the washing tower. One is that the load increases too quickly and the air flow speed suddenly increases, so that the water vapor has no time to separate. The other is that the fine ash content in the gas is too high, which makes separation difficult. The direct result of water entrainment is that liquid water is entrained in the gas entering the conversion furnace, soaking the conversion catalyst, causing high conversion resistance, deactivation of the catalyst, and in the worst case, the production can not operate. Generally, when engineering companies design, they need to add a moisture separator to separate the water before changing. In addition to taking water into consideration, condensed water must also be considered. To avoid carrying water, one is to ensure that the coal quality is as stable as possible, and the other is to avoid significantly increasing the load. (1) Under high load in the gasifier, the liquid level cannot be increased and does not reach the designed normal liquid level, which directly affects the effect of the syngas water bath. The first washing of the syngas is poor, and part of the ash will be entrained into the scrubber. (2) The gasifier may contain water. Since the quench chamber is in direct contact with the slag and fly ash from the gasifier combustion chamber, the water quality in the system is poor. A large amount of ash will arrive in the scrubber along with the water entrained in the syngas, affecting the water quality of the scrubber and the cleanliness of the outlet syngas. (3) The deterioration of the water quality in the scrubber will affect the quality of the quench water extracted from the scrubber. Long-term operation will aggravate the scaling of the quench ring of the gasifier, eventually causing the gasifier to shut down. (4) The condensate sprayed at the syngas outlet of the gasifier comes from the condensate pump. Since the outlet pressure is 4.8MPa, the pressure difference with the outlet of the gasifier is low. * * The small holes have been blocked by the ash in the syngas, and there is no washing with spray condensate, which has no infiltration effect on the fly ash in the syngas. (5) Venturi scrubbers are prone to scaling, which affects the effect of jet washing. (6) There may be problems in the design of the internal parts of the scrubber, the scrubbing effect is poor, and the syngas contains more water vapor and ash, causing the resistance of the conversion system to increase. 9) Regarding the pressure difference between Texaco gasification oxygen and the gasification furnace. The operating pressure of the device is different, and the required pressure difference is also different. It has a certain relationship with the size of the nozzle. You may be talking about the Lunan plant. The operating pressure is 2.8~3.0Mpa. The pressure difference between oxygen and normal operating pressure should be 1.0Mpa. The pressure difference between oxygen and coal slurry should be around 0.5Mpa to ensure the atomization effect. If the operating pressure is 6.5Mpa, the oxygen pressure entering the furnace should be 8.0~8.2Mpa, and the coal slurry entering the furnace should be 7.5~7.8Mpa. If the operating pressure is 4.0Mpa, the pressure difference between oxygen and gasifier is 1.2Mpa, and the pressure difference with the coal slurry is about 0.5Mpa. 10) How to adjust the load of the multi-nozzle gasification device. The oxygen flow is adjusted by the regulating valve, and the coal slurry flow is adjusted by the coal slurry pump. A coal slurry pump is divided into two counter-injection burners. The coal slurry flow rate is currently adjusted by frequency conversion, so there is no need to worry. ； As for the oxygen flow, generally speaking, a relatively precise regulating valve is used to adjust it, and the error will not be too large. Even if it is larger, it will not directly erode the furnace bricks after being ejected from the burner and then colliding in the furnace. Even when the oxygen flow rate fluctuated at 5% and the coal slurry fluctuated at 12%, the gasifier did not suffer from partial spray, let alone the better equipment. 11) Are black water and gray water the same concept? What is the conceptual relationship between blackwater treatment and flash evaporation? Black water, superficially understood as black water, is actually water containing most of the gasification residual carbon that is discharged directly from the bottom of the gasifier and scrubber. ； Gray water refers to gray water on the surface. In fact, it is the water containing most of the gasification residual carbon that is directly discharged from the bottom of the gasifier and scrubber. ； In other words, a flash is the dividing line, black water is in front of the line, and gray water is behind the line. In the Texaco process, black water is discharged from the gasifier to the flash evaporation system, and then enters the settling tank. After preliminary separation, part of the mortar goes to the filter press, and the remaining gray water enters the gray water tank, which is gray water. This part of gray water is mixed with the condensate from the conversion, then enters the deaerator, and then mixed with the water from the flash tank before entering the scrubber. In TAXECO gasification, the water after flash evaporation, sedimentation and dust removal can be called gray water. 12) What are the reasons why the gasifier of Texaco’s pressurized coal-water slurry gasification contains water? What measures should be taken to solve various reasons? 1. The load of the system is too high. The amount of syngas produced is large and the load needs to be reduced. 2. The pressure of the system suddenly drops and I don’t know what to do. Haha. 3. The liquid level in the quenching chamber is high and the temperature is also high. Pour in black water and add more quenching water. 4. The down pipe in the quenching chamber is broken. Stop and repair it. 5. The syngas pipeline may be blocked. It makes me feel suffocated and I don’t know how to deal with it, haha. 6. The operating temperature is too high, lowering the temperature and ash melting point. The process temperature at the outlet of the carbon washing tower is too high, and too much condensate in the tray will also bring water. 1: When the pressure or load increases, the intensity of the heat flow increases, which may lead to film boiling, which greatly reduces the conversion ability and the gas in the furnace carries water. 2: When the load is high, the airflow speed is also high, which will also bring water. ； 3: The upper and lower circulation pipes should match the original production load. Increasing production will also bring out the supersaturated steam water. ； 4: The water entrained when the distribution plate is separated cannot be effectively separated, and the water will be carried out with the air flow. 13) The reason why the cone bottom temperature is high during normal operation of the gasification furnace is that the cone temperature is over-temperature. It cannot simply be said that the flame moves downward, because the temperature in the furnace is above 1300 degrees, and the temperature of the cone in the furnace will not be low if the flame is close to the top. So I think the reasons for the high cone temperature are as follows:: 1) There are problems with the cone structure or the quality of the furnace construction, resulting in gas leakage and high-temperature slag entering the joints of the cone bricks, causing the temperature of the subject to rise. ； 2) Slag hanging at the slag mouth causes deformation of the slag mouth, and the biased flow of the process gas affects the cooling of the process gas in the downcomer, causing the temperature of the cone to rise at the location where the flow rate is large. ； 3) Slag hangs on the cone. When the furnace conditions are abnormal, the slag is wired to form needle-shaped slag, which accumulates in the cone as the process gas rises, resulting in a decrease in the heat exchange effect of the cone and an increase in the temperature of the cone. Among them, the first one causes the most. At this time, when the central oxygen amount is adjusted, the cone temperature will also change. There are also special situations, such as a large pressure difference at the slag port and a damaged gasket, causing hot gas to escape; there is also a burnout of the downcomer, which will also cause the temperature of the cone bottom plate to rise; these are very serious matters; in fact, the purpose of setting the temperature measurement point by the patentee was first to prevent the cone bottom bricks from gas leakage, and secondly to prevent the downcomer from burning through. These are very serious accidents; therefore, the rise in temperature at the cone bottom is an issue that everyone should pay attention to. The cone temperature is over-temperature, which means that the temperature of the trailer brick is high. I think the main points are as follows:: 1) The coal has large ash content and high load, and the slag will cause great erosion and thinning of the cone; 2) There are problems with the cone structure or furnace construction quality, resulting in gas cross-flow, high-temperature gas or slag entering the cone brick joints, causing the temperature to rise. ； 3) The oxygen flow rate in the center is too large, the high temperature zone moves down or the load is too large, causing the temperature to rise due to erosion of the cone; 4) Slag hanging at the slag mouth causes the slag mouth to deform, and the biased flow of process gas affects the cooling of the process gas in the downcomer, causing the temperature of the cone to rise at locations with high flow rates. ； 5) Slag hangs on the cone. When the furnace conditions are abnormal, the slag is wired to form needle-shaped slag, which accumulates in the cone as the process gas rises, causing the heat transfer effect of the cone to decrease and causing the cone temperature to rise; 6) The quench water flow rate of the quench ring fluctuates. Among them, the third and sixth causes are the most common. At this time, adjusting the central oxygen volume or stabilizing the chilled water flow will improve the condition. 14) How to deal with tempering in gasifier ovens? The main reason for tempering in gasifier ovens is that the pressure inside the furnace is higher than the outside, which causes the gas to be discharged to low pressure. Therefore, it is necessary to maintain a negative pressure inside the furnace, that is, use a suction pump to increase the negative pressure. At the same time, the exhaust must be made in time to prevent it from accumulating in the furnace, otherwise it will be difficult to draw negative pressure. As mentioned above, the gasifier liquid level cannot be too high, otherwise the gas will be difficult to discharge. 1. Turn off the oven fuel immediately. 2. Replace the combustible gas in the gasifier. 3. Check the reasons for tempering in the gasifier (high liquid level in the gasifier, small extraction air, blocked extraction air path, excessive fuel, gasifier not completely closed, condensate in the extraction gas separation tank not removed in time) and eliminate them. 4. Bake the oven according to the oven curve again. 15) Regarding the ignition method of the gasifier, the ignition of the coal-water slurry gasifier is not as troublesome as the ignition of the Shell gasifier. The Shell furnace is first ignited by the IB (ignition burner), then the SUB (starting burner), and finally the CB (coal burner). Under normal circumstances, IB ignition success is very high, but the problem is mainly on the SUB. Several domestic factories have burned out the SUB. , most of them are burnt out at the burner head. As long as the burner head is replaced, it can be used again. In Shell's original design, the SUB burner head is a replaceable part. There are strict requirements on the use time of the burner head. It seems that the burner head must be replaced after how many hours of continuous burning or how many times it has been used. I can't remember the specific number. Haha! The coal input amount in a single furnace of a Shell furnace is several times that of a coal-water slurry furnace. If only one ignition burner is used to light CB, the requirements for the ignition burner are too high. 16) How to reduce the carbon residue in the ash. Inspection and analysis of the reasons for high carbon residue in the slag: 1. The raw material particle size is uneven, the particle size difference is too large, or the gangue contains too much powder, the furnace temperature cannot be increased, and the raw material reaction is incomplete. 2. The upward blowing time is long, the steam consumption is large, the gasification layer moves upward, the furnace temperature is low, and the raw material reaction is incomplete. 3. There are scars in the furnace, the wind tunnel or the gasification layer are not well distributed, and the raw materials are not fully reacted in the gasification layer for a short time. 4. Equipment defects: The grate has uneven ventilation and poor slag breaking ability. The grate machine pulls too fast and the raw materials do not have time to react. The baffles on both sides of the furnace failed and carbon leaked. 5. The raw coal has poor activity. Solution: 1. The processing of raw materials should be strengthened to ensure uniform particle size of raw coal entering the furnace and clean gangue. 2. Adjust the up and down blowing percentage or blow the steam up and down to keep the vaporized layer in the appropriate position, thickness and temperature. 3. Deal with the wind tunnel scars in the furnace and optimize the furnace conditions. 4. Check and treat or replace the grate, adjust the appropriate speed of the grate machine, and check and treat the slip plate. 5. Replace coal with poor activity. 17) Why coal-water slurry gasifiers do not use water-cooled walls but always use refractory brick water-cooled wall structures? There is no patent issue. This is very common in the boiler industry, and any boiler factory with certain strength should be able to design and manufacture it. In fact, the reason why the water-cooled wall structure is not used is based on the principle of coal-water slurry gasification. CWS gasification brings too much water into the system, causing part of the carbon in the coal to be oxidized into carbon dioxide to provide sufficient heat for the gasification system. This is why the amount of carbon dioxide in the crude syngas of CWS gasification is much higher than that of pulverized coal gasification. If a water-cooled wall is used, the gasification system will lose an additional part of the heat to the water-cooled wall, which will cause the amount of carbon dioxide to further increase and the effective gas ratio to further decrease, affecting the gasification efficiency. This is very different from pulverized coal gasification. 18) How to deal with slag blockage in the lock bucket? 1. Reasons for slag blocking: There are generally two situations for slag blocking in the lock hopper.: 1. Slag blockage. Generally, it is caused by the high ash melting point of the coal burned in the gasifier, slagging due to temperature fluctuations in the gasifier or leakage of quenched slagging in the gasifier (shell gasifier water wall, burner flame shield, hot skirt, etc.) and hanging slag accumulated at the lower slag port falling off. For Texaco furnaces, there is also "brick slag" formed by the peeling off of refractory bricks due to temperature fluctuations. This kind of slagging is larger than the slag lock hopper channel or bridge, which will cause slag discharging to be blocked. In severe cases, slag and material cannot be discharged. 2. Mud clogging. When the temperature of the coal (low ash melting point) in the gasifier is too low, the combustion is incomplete and begins to partially turn into ash granules before rapid cooling. The ash content is relatively high, resulting in less granules, too much water content, muddy shape, and high viscosity. It will accumulate in the lower part of the lock hopper, and after the deposition is compacted, it will form a bridge and block the unloading. 2. Treatment methods 1. Preventive measures: Timely analyze the ash melting point of coal, add an appropriate amount of flux, keep the material stable, the oxygen-to-coal ratio is moderate, keep the temperature of the gasifier stable, and maintain the fluidity of the slag. Once slag blocking occurs, the working conditions should be adjusted in a timely and gentle manner. ； 2. Maintain the water level indicator and appropriate water fluidity in the lock bucket to prevent slag deposition and compaction to build bridges. ； 3. Slag blocking treatment: The most effective method is to connect a pressure water flushing line to the lower part of the lock bucket. When slag is blocked, manual "bridge removal" is performed, program control is changed to manual intervention, intermittent high-pressure water flow is reversely flushed to loosen it, and then the slag discharge operation is performed. Repeated many times, it will be effective. The pressure of the flushing water should be higher than the pressure in the lock bucket but not too high. If it is too low, the loosening effect will not be achieved. If it is too high, the water content in the gasifier will suddenly increase or even open water will enter, causing equipment safety accidents. The theoretical data of pressure difference control needs to be calculated based on the specific furnace. Personal experience is that controlling it at 1.0~1.5MPa works well. Generally, this method is more effective for the second reason than the first. The first type is slightly more difficult to handle. Of course, if the bucket lock valve cannot be opened or large pieces of slag cannot be loosened, it will not be taken away, and in the end the work will have to be stopped. 19) The raw material transportation of dry coal gasification technologies such as shell and GSP requires nitrogen. Do they have any special requirements for the quality indicators of nitrogen? Can general air separation plants meet its requirements? The power nitrogen in the raw material transportation part only needs to have an oxygen content lower than 5% of the polluted nitrogen and meet the safety requirements during the preparation or transportation of pulverized coal, that is, the lower explosion limit is 50%. After being used in the reaction section, the nitrogen used for purging, backflushing, etc. will enter the crude synthesis gas and may affect downstream chemical equipment. Its purity is required, and it should generally be at the PPm level. This can be relaxed if it is IGCC. Generally, large-scale air separation units can easily meet this requirement. Unless there is a design or modification error, the ASU becomes a waste nitrogen machine. 20) GSP pulverized coal gasification pressure 1. "The gasifier operating pressure of GSP gasification technology can be selected from 2.5-8.0MPa" is a theoretical aspect. The actual situation is that the operating pressure can only reach a maximum of 4.0MPa, which is determined by the pulverized coal transportation system. If the operating pressure continues to be increased, on the one hand, there may be problems in producing ultra-high pressure nitrogen, and on the other hand, equipment investment will also increase significantly due to the increase in operating pressure. 2. Currently, the largest device operated by GSP in the world is the 130MW gasification device built in Germany in 1984 (lignite input is 720-750t/d, gas production is 50,000Mm3/h, the inner diameter of the gasifier is 1.9m, and the inner diameter of the pressure vessel shell is 2.4m). The design pressure is only 3.0MPa, and the working pressure is only 2.5Mpa. 8.0MPa pulverized coal gasification is just an idea. The gasification pressure of GSP, SHELL and two-stage furnaces can only reach 4MPa at present. No matter how high the pressure is, not only do you have no design experience, but there is no need for it at the moment. You just need to take a look at the driving of the shell. The one with lower pressure drives better. Therefore, there is currently no need to increase the pressure of pulverized coal gasification. The top priority is to solve the problem of stable operation and reduce the number of shutdowns. Don't burden this craft. 21) Why does TEXACO's crude gas need to be mixed with the process condensate first and then washed in the venturi after it comes out of the gasifier? Is it okay to go to Venturi directly after coming out? When designing, Texaco did add part of the condensate to the outlet of the gasifier. The main purpose was to prevent the outlet of the gasifier from being blocked. However, with the domestic digestion of Texaco's technology, the key is the increase in operating levels. Many devices no longer use this method, and the condensate is eliminated in the design of new devices. The original design included the need to add part of the condensate to the outlet of the gasifier, but the current design generally does not. Moreover, it is not used to cool the quench water in normal times. Based on long-term implementation, this water is not ideal for slag removal, so this is not included in the current design. The actual cooling, dust removal, and saturated process gas are still in the quench chamber of the gasifier. 22) Is there any requirement for the temperature of the syngas leaving the quenching chamber? Some literature says it is around 220°C, and the Huainan process package data is 227°C. Generally, the temperature leaving the quenching chamber is controlled at around 220 degrees, but it will change with different production conditions. For the same type of furnace and the same type of coal, temperature changes generally reflect changes in the water level in the quenching chamber. There is no upper limit to the temperature, but a lower limit to the water level. Within this temperature range, no damage will be caused to the downcomer. The temperature of the syngas leaving the quenching chamber is usually the saturation temperature under the corresponding pressure. Since the syngas contains water, the water in the syngas is supersaturated, and the temperature is generally lower. The pressure of the Huainan gasifier is 4MPa, and the corresponding saturation temperature is 250.3°C, so the 227°C in the process package is reasonable. 23) Are the water inlet volume of the tray and the water replenishment of the tower kettle of the carbon scrubber fixed? Are they related to scrubber liquid level control? After production is stable, these two quantities should be basically fixed and are related to the liquid level of the scrubber. The tray water volume is mainly determined by the ash content of the tower gas. The water replenishment of the carbon washing tower tray is very important in actual operation. The amount of water supplied in this way has an important impact on the ash content of the syngas. Simply put, it is used to wash the syngas. If there is less water in this path, the syngas will have more ash after it leaves the carbon scrubber. If it is run like this for a long time, the conversion efficiency of the conversion path will be reduced due to severe ash. The amount of water supplied to all trays is not fixed and must be determined according to the degree of ash in the syngas. In addition, when the load is high, the amount of water added must increase accordingly. As for replenishing water in the tower kettle. The amount of water replenishment should also be adjusted according to the liquid level of the carbon scrubber. 24) Water cutting after the gasifier is stopped under various circumstances 1. Stopping during operation. If the gasifier is stopped during operation, the water cutting will be notified after closing the burner valve on site. This is because the gasifier pressure maintenance is under ideal conditions. No gasifier can completely maintain pressure. In order to prevent the gasifier liquid level from being high due to low pressure and inability to discharge water, water must be cut to the start-up pipeline as soon as possible. 2. Planned shutdown: Reduce the planned shutdown boiler load to half load, cut water to the start-up pipeline, and then shut down. The same is to prevent water from being drained. 3. Plan to shut down the furnace, plan to stop the furnace and reduce it to half load, and plan to start the furnace to feed materials. After feeding, the water will be removed from the construction pipeline. When the charging furnace pressure rises to the same level as the operating furnace, the water is cut to the flash evaporation system. Plan to shut down the boiler and cut water to the starting pipeline before shutting down. Some people may be worried about the pressure of the start-up pipeline. In fact, the pressure design of the start-up pipeline is the pressure of a single furnace at full load, because if there is a problem with the flash evaporation system, the water still has to be cut to the start-up pipeline and isolated for treatment. Of course, the time cannot be too long. 25) How to adjust the central oxygen content of the multi-nozzle device when it is started, stopped, and the production load is adjusted? What is the purpose of the adjustment? The single nozzle of coal water slurry gasification is a premixed burner, which requires a long flame and the central oxygen content is controlled to about 15% of the total oxygen content. ； The four nozzles are pre-film burners. The flames are sprayed oppositely to form a plum blossom shape. The required flame is shorter, and the central oxygen amount plays a more obvious role in the length of the flame. Its control range is 8~12% of the total oxygen amount. If the control ratio is too large, it will easily cause the gasifier vault to overheat and damage the refractory bricks. 26) In a multi-nozzle device, one pair of burners trips and the other pair of burners runs for a short period of time. How to operate this gasifier. This kind of gasifier has two coal slurry pumps, each supplying a pair of burners. If one pair trips, the other pair can still continue to operate, but it is necessary to reduce the load and reduce the pressure. The fault must be eliminated as soon as possible to put the tripped burners into use. After a pair of burners is tripped, in order to prevent dry burning from damaging the out-of-service burners, a large amount of nitrogen must be passed into the tripped burners for protection. If the feed can be fed as soon as possible, and it is an ammonia synthesis device, short-term protection will have little impact on the system. ； If methanol is synthesized, there will be more trouble. If the feed cannot be fed as soon as possible, a large amount of nitrogen will enter the synthesis gas, and the gas composition will deteriorate, which will have a great impact on the subsequent processes of the device. Therefore, theoretically speaking, this setting itself is not a big problem, but in actual industrial production, generally a pair of burners does not need to be stopped when the outage time is very short. If the time is slightly longer, it should be stopped. After a pair of burners is out of service, it is necessary to reduce the load. As for continuous operation under pressure, since the system pressure itself will decrease after the load is reduced, it is enough to directly put in coal slurry and oxygen and slowly restore it. 27) What is the reason for abnormal fluctuations in gasifier pressure? 1. Fluctuations in pressure in the gasifier caused by pressure fluctuations in the gasifier. 2. Fluctuations in oxygen flow, pressure and purity (this possibility is very small), resulting in changes in the reaction in the gasifier. 3. Fluctuations in coal slurry concentration and flow (the high-pressure coal slurry pump has a cushion phenomenon or large particles in the coal slurry), causing changes in the gasification reaction. 4. It may be that the system's self-regulating valve surges after the syngas is removed, which affects the system pressure (especially when this valve is a butterfly valve self-regulating valve). Due to abnormal fluctuations in the pressure in the furnace and without any adjustment of the oxygen valve, the oxygen flow rate will also decrease as the furnace pressure rises and increase as the pressure decreases. Fluctuations in the oxygen flow rate will inevitably lead to fluctuations in the temperature in the furnace. Therefore, when there are abnormal pressure fluctuations, the oxygen flow rate must be adjusted in time to avoid excessive temperature fluctuations in the furnace. 28) When Texaco pressurizes coal-water slurry for gasification, how to determine whether the gasifier and carbon washing tower are filled with water? The gasifier is carrying water: the water inlet volume of the gasifier has not changed, the drainage volume has been reduced, and the liquid level is high. It may also be due to too fast loading. Or the oxygen-to-coal ratio is too high. The scrubber is carrying water: the temperature of the process gas at the top of the scrubber has dropped, and the liquid level is high. The amount of water in the tray is too high. 29) How high should the burner pressure difference be controlled? A high burner pressure difference is beneficial to atomization, but it also increases the wear of the burner and affects the service life of the burner. Texaco's designed burner pressure difference is 1.2~2.4. I think it is more appropriate to control it at about 0.5Mpa. The burner pressure difference of our gasifier at full load is about 0.6Mpa. It is definitely not good if the pressure difference of the burner is too low, and the dome bricks are prone to problems, but if it is too high, it will aggravate the erosion of the cone bottom bricks. Therefore, after many years of summary, it is believed that it is more appropriate to control it at 0.6Mpa. This requires that when designing the burner, the burner gap should be adjusted properly! 30) For a four-nozzle gasifier, when the flow rates of the two opposing nozzles are inconsistent, how is the operation adjusted? If the flow rate difference between the two nozzles exceeds a certain range, is there any interlock in the control? The flow rate of the coal slurry pump is only related to the speed of the pump, but it cannot ensure that the resistance of the two pipelines is consistent. In the design, the resistance of the two pipelines is considered to be consistent, but the actual situation is not entirely like this. The flow rate produced by our coal slurry pump is not completely consistent. That is to say, the issue of flow difference that the poster is considering is that a certain flow difference can be allowed in the process. As mentioned downstairs, when the flow difference reaches the set value, it will cause a chain trip, but the flow rate of the two pipelines of the same pump cannot be adjusted. There is also a flow chain between two pairs of burners, that is, a large flow difference between the two pairs of burners is not allowed, otherwise it will also cause the car to trip. 31) Coal-water slurry with good slurry-forming performance has a certain range of particle size distribution. If the proportion of pulverized coal with coarse particle size is larger, the concentration and fluidity of the produced coal-water slurry will be improved. ； If the proportion of fine coal powder is larger, the stability of the produced coal-water slurry will be better. So please discuss it based on your own actual production experience.: What influence does the coal water slurry particle size distribution (or the ratio of coarse and fine particle size of coal water slurry) have on Texaco gasification? Coal slurry coarse particles that are too high or too low are detrimental to production. If the proportion of coarse particles is larger, the gasification efficiency will decrease, but the concentration of coal slurry will increase, and the water substituted into the furnace will be reduced accordingly, and energy consumption will be reduced. The larger the proportion of fine particles, the more gasification efficiency will be improved. Although the stability of the coal slurry is good, the concentration of the produced coal slurry will be affected, the moisture brought into the furnace will increase, and the energy consumption will increase. Therefore, the uniform particle size distribution of coal slurry is conducive to improving gasification efficiency and reducing energy consumption. 32) What are the reasons for the high temperature of the gasifier pallet bricks (support plates)? How to deal with it? It is estimated that there are several possibilities: 1. Excessive ash collection in the upper part of the quenching chamber 2. There is air leakage 3. The burner is not adjusted properly 4. The load is too large 5. There is a problem with the spray water (for new quenching chambers) a The cone bricks have fallen off more seriously, so the temperature is high and the bricks need to be stopped for maintenance and replacement. b Either the flushing water flow rate drops, causing the temperature to increase. c. The operating temperature of the gasifier is too high, lower the operating temperature. d Thermocouple false indication. 33) What is the difference between Texaco's coal-water slurry gasification technology using premixed nozzles and multi-nozzle opposed coal-water slurry gasification technology? What is the difference in the structure of the nozzle? The same as the Texaco coal-water slurry gasification burner, the pre-film burner used in the four-nozzle opposed coal-water slurry gasification furnace also adopts a three-flow channel structure, that is,: The oxygen stream entering the burner is divided into two flow channels. The inner cavity of the small nozzle is filled with central oxygen, and the annular gap formed between the inner cavity of the large outer nozzle and the outer surface of the middle nozzle is filled with epoxy. ； The annular gap formed by the inner cavity of the middle nozzle and the outer surface of the inner small nozzle carries coal-water slurry. The head of the pre-film burner is also equipped with a water jacket and cooling coil to resist the high temperature in the furnace from baking the external large nozzle. Different from the Texaco coal-water slurry gasification burner, the end faces of the small and medium nozzles of the pre-film burner shrink inward by only 1mm relative to the end face of the external large nozzle. Oxygen and coal-water slurry leave the burner at the same time. There is no premixing chamber for oxygen and coal-water slurry at the burner head, making it an external mixing burner. ； As for Texaco's coal-water slurry gasification burner, the middle nozzle is axially retracted by a few millimeters compared with the external large nozzle, while the internal small nozzle is axially retracted by dozens of millimeters compared with the external large nozzle. The head of the burner forms a premixing chamber for oxygen and coal-water slurry, which is an internal and external mixed burner. The end structure of the pre-film burner causes the three streams of material to form a coaxial intersection when they are ejected. Because the coal-water slurry is in the shape of an annular film before it is ejected from the burner, it is called a pre-film burner. 34) When the slag port is clogged in Texaco gasification, the slag sample contains glass filaments. Why is this? The filamentous shape should be caused by the low viscosity of the slag. The blockage of the slag port indicates that the high viscosity and poor fluidity of the slag accumulated in the furnace before. After the furnace temperature rises rapidly, the flow rate exceeds the circulation capacity of the slag port. Of course, the above is based on the current coal quality. Even if the oxygen-to-coal ratio or gasification temperature is the same, this situation will occur due to the rapid change in the viscosity-temperature characteristics of coal ash. According to the infrared spectrum analysis, when the coal ash is around 1300 degrees, the main components in the ash are Al2O3, SiO2, CaO, etc. The main components are mullite, feldspar, green gangue and amorphous glass body and other silicate materials. When the temperature of the gasifier is high, the molten glass body mainly composed of SiO2 in the liquid slag is blown into filaments under high-speed air flow, and after cooling with quenching water, it becomes golden (some yellowish, some white) needles and filaments. In actual production, the appearance of needles and filaments in the slag is often used as one of the reference phenomena for judging the high temperature of the gasifier. 35) What is the reason for the damage to the SHell burner flame muffle and the start-up burner? Are there conditions for the generation of carbonyl iron near the CB Muffle that may pose a threat to it? If there is a possibility of producing carbonyl iron, how can it be suppressed? 1. Iron is a transition element, and its atoms produce an electron layer that is not fully filled with the structure. When it interacts with carbon monoxide to form fe(co)5, it consists of iron atoms and 5 co molecules to obtain insufficient electrons. 2. Production conditions: Fe(CO)5 (pentacarbonyl iron) is synthesized from CO and elemental iron under high pressure. The production and preparation uses coarser sponge iron powder as raw material. After granulation, it is annealed and activated in hydrogen at 350 degrees, and then placed in a reactor. The iron particles are exposed to circulating CO, the gas pressure is 6 OPMa, and the temperature is 160 degrees. Iron reacts with CO to obtain gaseous Fe(CO)5. The material of the shell coal gasification CB Muffle is 15CrMoG. The pulverized coal from the burner ejects upward swirling gas. The radial plane of the burner is not a high concentration area of ​​CO. The temperature of the gasifier is around 1600 degrees, and the outer surface of the flame muffle is also around 460 degrees, which does not meet the conditions for the formation of carbonyl iron. Crystal phase analysis of CB Muffles that were damaged during production showed high-temperature ablation leakage, with localized pitting and pitting corrosion on the surface, but no surface flake corrosion. At present, the three Sinopec companies have successfully solved this problem without changing the materials. Among them, there was no damage during the shutdown in Anqing from March to October, and there was no damage after May in Zhijiang, Hubei. The recent shutdown inspection found no problems. Therefore, the current material of CB Muffle is not likely to form carbonyl iron under the operating conditions of the shell gasifier. 36) SHELL coal burner, why is the coal burner easily burned out? What methods can be used to avoid or take some measures to reduce the probability of the coal burner being burned out? Since the start of operation at the end of 2006, none of the three Sinopec companies has experienced coal burner damage. The only damage was the burner flame shield and the start-up burner. However, among the five that have started construction, one manufacturer did burn out a coal burner. They asked a domestic research institute to research and trial-produce one. It is hard to say much about the specific details. But what I want to say is that the trial-produced burner has not been used until now. The main reason is that I am not at ease. At present, the imported spare burner is still used to replace the damaged one. The cause of the damage is not talked about much. Personal analysis is mainly peroxide ablation. Overoxygen mainly occurs during driving or coal line fluctuations. Another situation that needs attention is that when the coal type changes, the adjustment is not timely, and the fluidity of the slag changes. The slag covers part of the oxygen/coal channel of the burner, forcing the direction of the fluid to change. Oxygen and coal cannot be fully mixed. Oxygen may even appear to flow back through gaps. Over-oxygen may occur locally or on the side of the burner head. This does not rule out local high-temperature oxidation and over-temperature ablation of the burner head. For a coal burner that has been made, the cross-sectional area and heat transfer capacity of its cooling water channel have been determined, and its maximum water flow capacity cannot be changed, so I think there are two points that need to be grasped. The first is to ensure water quality. If scaling or blockage occurs in the water channel, the water flux and heat exchange capacity will be significantly reduced, which will seriously affect the service life of the burner. The second is to ensure that the heat load does not exceed the limit of heat exchange capacity, that is, the oxygen-to-coal ratio must be strictly controlled. Changes in the oxygen-to-coal ratio lead to changes in combustion. The reasons for this include gas transportation. Because there are fluctuations in coal transportation during the transportation process (gas transportation), it is easy to cause an imbalance in the ratio of coal to oxygen. This is also a flaw of SHELL itself. 37) Reasons for the continued increase in outlet temperature of SHELL coal gasification syngas cooler 1. The quench gas flow rate decreases, and the fault should be checked immediately to eliminate the fault and restore normal flow. 2. If the O/C ratio increases, it should be adjusted to the appropriate ratio immediately. 3. The circulating water flow is low and the circulating water flow should be increased immediately. 4. Dust accumulation inside the gasifier and cooler reduces the heat exchange efficiency. The rapping device should be activated immediately to remove the dust accumulation. Supplementary disposal methods: 1. The resistance drop of the subsequent system can be reduced where possible, so that the gasifier can operate at the lowest possible pressure to facilitate dust cleaning. 2. When the load is low, high ash content or high iron coal quality can be used for alternate cleaning. 3. Improve the control level of gasification furnace temperature. 38) Points to note when operating fixed-bed gasifiers with poor coal quality. Due to the current shortage of coal resources, the lump coal used in fixed-bed gasifiers will be limited due to price reasons, and some poor coal will also be blended, so stable operation is crucial. You can start from the following aspects: 1. Strictly control the bed resistance. That is, maintaining a certain fire layer thickness ； 2. Ensuring a certain ash layer is the basis for fixed bed gasification. When the gray layer is destroyed, it is nonsense to say otherwise ； 3. When coal quality deteriorates or changes, different operating methods should be adopted according to the coal quality analysis, rather than being static. a. If the ash content of coal is high, the speed of the grate machine can be appropriately increased. At the same time, the upward blowing time or the amount of upward blowing steam must be increased. Do not lower the furnace temperature. ； b. If there is a lot of crushed coal and pulverized coal, the bed resistance will increase. You should first focus on reducing the bed resistance, but avoid blowing over oxygen. You can reduce the height of the bed and the thickness of the fire layer, and at the same time slow down the speed of the grate machine to prevent damage to the ash layer and cause the furnace temperature to drop and cause carbon collapse. When the resistance is almost the same as normal, increase the speed. ； Furthermore, at this time, you must not increase the resistance just for the sake of the fire layer. ； Appropriately adjust the upper and lower blowing ratio and blowing intensity, and blow as weakly and as long as possible to maintain the furnace temperature. ； c. When the ash melting point changes and agglomeration occurs, causing wind tunnel, blowing over, furnace temperature deviation, redness, etc., the blowing intensity must be reduced first, but the furnace temperature must not be lowered! Assists manual efforts to remove blocks, hold back dust, or reduce loads. In short, keeping the resistance of the ash layer, fire layer and bed layer uniform is the key. (1) Selection of wind pressure and air volume The key to burning inferior coal well is the selection of wind pressure and air volume. Large air volume and low air pressure are the dominant directions. If the air volume is too small, it will take a long time to raise the temperature, which may easily lead to shortcuts in the blowing, local overheating, scarring, and drifting charcoal. If the air pressure is not selected appropriately and is too high (above 26 kPa), it will be difficult to control the temperature of the upper furnace and it will easily blow over the wall. (2) Selection of cycle time percentage The cycle time percentage should be selected according to the actual situation of each factory. Because the heat storage capacity of the bed of inferior coal is small, the gasification layer should not be too thick, so long circulation should be the main method. (3) The selection of the amount of upper and lower blowing steam must first ensure the stability of the steam pressure entering the furnace. Our company’s steam pressure for burning lump coal is controlled at 0.06±0.05 MPа. According to the characteristics of inferior coal, the steam pressure entering the furnace can be slightly increased by 0.005 MPа, at the same time, increase the hand wheel of the upward blowing steam valve by 1 to 2 turns, so that the amount of steam used in upward blowing is slightly larger than that in downward blowing, so that the gasification layer has good ventilation effect and the medium contacts each other for a long time, which can increase the steam decomposition rate, reduce heat loss, loosen the scars, and form a stable ash layer. When the coal quality and furnace conditions are stable, analyze the CO2 content in the upper and lower blows to adjust the steam hand. * * Small (up-blowing CO2 content is controlled at 7.0% ~ 8.0%, down-blowing CO2 content is controlled at 4.0% ~ 5.5%). (4) Control of carbon layer height and furnace temperature Effectively controlling the carbon layer height is the key to stable furnace conditions. A relatively stable carbon layer height will result in a stable gasification layer. Large fluctuations in the carbon layer height will seriously damage the gasification conditions, which will ultimately lead to reduced gas production and increased consumption. It is not suitable to operate with a high carbon layer. In daily operation, we found that after the carbon layer is controlled above 2.2 m, the higher the carbon layer, the slower the charcoal layer declines (that is, the gasification is obviously not good), resulting in the charcoal layer getting higher and higher, and the grate machine is getting bigger and bigger, entering a vicious cycle. When the temperature of the ash bin and the furnace bottom rises, and the lower ash has a red fire of charcoal, the grate machine does not dare to expand anymore, the charcoal layer rises faster, and the gasification layer begins to be disordered. Finally, the temperature of the upper furnace rises sharply, causing the hanging furnace to blow over. Therefore, the carbon layer height must be strictly controlled. In terms of furnace temperature control, we choose the upward temperature to be below 260°C, with 220 to 240°C being the best. ； The downward temperature is controlled at 250±30℃. It is appropriate for the downward trend to be 20°C higher than the upward trend. It should be particularly pointed out that the upper limit of the rising furnace temperature should be strictly controlled. Running high is a precursor to the deterioration of the furnace temperature and must be strictly assessed and controlled. 39) Where does the Texaco quench water enter the gasifier? Generally speaking, there is an interface under the syngas outlet of the gasifier. The pipe number should be marked N5 on the drawing. This is the entrance of the quench water into the gasifier. At the production site, there should also be a quench water distribution ring on the platform above the entrance. The external quench water first distributes the ring and then enters the four N5 pipe ports. Roughly speaking, the quench water is pumped out by an extremely cold water pump, filtered by the filtration facility, and then divided into four channels into the gasification furnace. In the furnace, it passes through four connectors (of different lengths) connected to the quench water pipe (flange connection) and enters the annular flow channel of the quench ring that is connected (welded) to the top of the downcomer. Then, it passes through the opening in the inner annulus and flows down evenly in a slightly circular shape along the outer wall of the downcomer into the water at the bottom of the quench chamber. 40) Is the gasification of Texaco's coal-water slurry into converted water gas serious? Is it necessary to install a separator at the beginning of the transformation section? How to consider the separation water volume if setting up a separator (regarding the selection of liquid level control valve)? Where does this water generally choose to be discharged, and where does it return to be vaporized? Generally, a Texaco system with a single nozzle carries less water and does not need to add a separator (depending on the level of the operator). However, for a furnace with four nozzles, the water volume is larger than that of a single nozzle. It is best to set up a separator, and the separated water can be returned to the gasification for continued use (this water is quite clean and can be used for gas scrubbing. The four nozzles are the same as the single nozzle. The gas and liquid are in direct contact in the scrubber. What comes out is saturated gas. When the pressure is constant, the temperature is basically the same. The steam-to-gas ratio is between 1.3 and 1.4. The main reason for the water is the problem of controlling the liquid level in the scrubber. In order to prevent the liquid water from directly reaching the transformer and affecting the transformer, a gas-water separator needs to be installed before the transformer. Of course, it is also possible that the pipeline is too far away and there is some condensed water (the amount is very small, the latent heat of steam is very large, and it is not easy to condense). Therefore, if there are no major problems with the scrubber, we should mainly work on the operation control to avoid water. A separator is required: 1. It is easy to bring water in during the early stages of driving or when the gasification operation is unstable! 2. Condensation in the gasification-to-transformation pipeline is inevitable, and the farther away, the greater the amount of condensation. ； 3. Act as a buffer to adjust the water vapor ratio ； 4. Wash and separate the gasified fine coal ash! It is very necessary to set up a separator. Its function is to protect the conversion furnace catalyst. Who can guarantee that the carbon washing tower will not contain water? ； Whether the water content of the carbon washing tower is serious or not is mainly related to the design parameters, carbon washing tower structure, and tray design. Of course, the operation is also very important. However, the water content of the carbon washing towers of all domestic manufacturers is basically within the controllable range. There are also some manufacturers with serious water content, but there are relatively few. No more enumeration. The liquid level of the separator can be determined by double flange level gauge or float level gauge. ； Because the temperature of the water is high and the water volume is small, the oxygen tank can be removed after decompression. 41) The most easily worn part of a multi-nozzle gasifier is the dome, which is why the dome is always overheated. Would raising the height of the vault solve this problem? There is no way to modify a gasification furnace that has been finalized. The difficulty and cost are too high, but the only place that can be moved is the refractory bricks. Therefore, when building the furnace, pay attention to the arrangement of the refractory bricks. It is best to make the refractory bricks on the top of the furnace into diversion troughs to guide the flushing airflow in the opposite direction for convection. This can reduce the flushing force, that is, reduce the flushing of the furnace top. Enlarging the space above the burner can avoid the wear of the refractory bricks on the vault ； The multi-nozzle technology is different from Texaco in the flow field. It belongs to the collision flow field, which is theoretically more advanced than the Texaco flow field. It turns out that the Cathay gasifier is over-temperature, and the typical vault space is insufficient, which causes the refractory bricks in the vault to wear more. Over-temperature is inevitable. The operation of the third gasifier also reflects that it is right to increase the size of the vault space! 42) The quench water filter is usually a spare when in use. Is it necessary? If the water inlet valve is open, or the outlet valve is open? It is necessary to switch the quench water filter to one standby! ! If the filter becomes clogged and the flow of quenching water becomes smaller, switching or using a backup filter can still restore stable production. The inlet and outlet valves of the backup quench water filter must be closed before being put into use. No matter which valve you open, a dead space will be formed in the backup filter body. Once sedimentation occurs, it will become blocked and it will not function as a backup at all. It is absolutely prohibited to stop the quench water during the operation of the gasifier. Even a brief interruption of the quench water may cause serious consequences of burning out the quench ring. Therefore, backup equipment must be installed for safety. 43) When the system is in the commissioning stage, the instruments need to be interlocked and debugged. What debugging should be done on the lock bucket at this time? 1. Lock bucket program operation and debugging ； 2. Interlocking debugging of lock bucket slag inlet valve and lock bucket slag discharge valve ； 3. The liquid level of the gasifier is low, and the lock bucket safety valve interlocks "off" test ； 4. The liquid level in the lock hopper is low, and the slag discharge valve interlocking "off" test ； 5. Lock bucket operation, lock bucket maintenance, lock bucket manual/automatic mode test ； 6. Valve action test caused by high or low pressure difference between the lock bucket and the gasifier. 44) What are the technical requirements for coal quality for coal-to-gas production? Different gasification technologies have different coal quality requirements. The rough situation is roughly: 1. The ash melting point of fixed bed gasification technology cannot be lower than a certain temperature because it is solid state slagging. ； High ash content does not matter2. The ash melting point of dry pulverized coal gasification technology cannot be higher than a certain temperature. The coal ash is melted during the gasification process and then extremely cooled and solid state is discharged. ； Higher ash content doesn’t matter (at least that’s what the market says in theory) 3. The ash melting point of coal water slurry gasification technology is required to be between the above two (? ? ) ； It seems that high ash content will not work. 45) General information will mention that the optimal temperature of the coal-water slurry gasification reaction is 50°C higher than the ash melting point (T4). This is a theoretical data. In actual production, there should be a certain reaction temperature. During the commissioning process, what kind of test method should be used to determine the reaction temperature? Currently, production plants using GE Texaco gasifiers usually determine the oxygen-to-coal ratio and operating temperature based on experience. The usual practice is: 1. During the initial start-up period, when the thermocouple can correctly indicate the temperature in the gasifier, a curve corresponding to the CH4 content and temperature in the syngas can be drawn as one of the guidance bases for subsequent operations. 2. After the thermocouple fails, there are several indicators that can help determine the oxygen-coal ratio to change the operating temperature.: (1) CH4 and CO2 content in syngas ； (2) Gasification furnace slag mouth pressure difference ； (3) Slag discharge state (it seems to be rarely used). However, an interesting phenomenon has recently been discovered. Usually liquid slag furnaces are required to operate at 50 to 100 degrees above the ash melting point. However, in fact, many coal-water slurry gasifiers now operate at temperatures lower than the ash melting point. There is no problem of slag blocking during operation, but the service life of the refractory bricks is long. * * extend. This issue deserves study. The properties of coal slag that need to be considered mainly include ash melting temperature, ash composition, ash morphology, etc. For coal types whose ash fusion temperature is too high, fluxing agents must be added to reduce the ash fusion temperature of the coal slurry. This is not only to meet the needs of molten slagging, but also to consider operating at a lower furnace temperature to protect the service life of the refractory bricks. Texaco's gasification process requires the operating temperature of the gasifier to be 50°C to 100°C above the ash fusion temperature to ensure smooth slag discharge from the gasifier. Practice has proven that the principle of controlling the operating temperature of gasifiers is not scientific because some coal types have low ash melting temperatures and high viscosity. Even if the ash melting temperature is above 100°C, the slag cannot be discharged smoothly because the viscosity of the ash is too high. Therefore, the operating temperature is selected based on traditional foreign experience, and the results are not ideal. Later, it was concluded that the gasifier temperature should be controlled based on the principle of taking the viscosity of liquid slag as the control target, that is, the optimal operating temperature of the gasifier should make the corresponding ash slag viscosity μ range from 25 Pa·s to 40 Pa·s. In order to reflect the melting fluidity of ash and slag at different temperatures, it is necessary to analyze the ash viscosity and temperature characteristics of the coal used, and find the optimal gasifier operating control temperature combined with the ash and slag viscosity control range. Adding an appropriate amount of fluxing limestone to the coal slurry can reduce the ash melting temperature, change the acid-base ratio in the ash, and change the shape of the slag (glass slag). Adding an appropriate amount of fluxing agent can reduce the operating temperature of the gasifier, but the elasticity of the operating temperature must be determined based on specific analysis. If possible, the specific morphology and physical and chemical structure of the slag should also be analyzed to understand its melt polymerization performance and physical abrasion performance, so as to provide a rich theoretical basis for the stable operation of the slag system. 46) How to deal with the slag water coming out of the gasifier? In addition to using three-level flash evaporation and four-level flash evaporation, what other methods are there? Which one is more effective? Texaco's process, the gray water treatment process of Texaco's coal-water slurry gasification process generally adopts high-pressure flash evaporation with vacuum flash evaporation process. Due to different gasification pressure levels and flash steam uses, flash pressure and process settings are different. Currently, the existing processes mainly include two-stage flash evaporation, three-stage flash evaporation plus stripping and four-stage flash evaporation. The purpose of high-pressure flash evaporation is waste heat recovery, and the heat of flash steam is generally used for deoxygenation and heating of circulating gray water. In comparison, the temperature of the concentrated gray water after the four-stage flash evaporation or stripping process is lower, which is conducive to the clarification of gray water. Therefore, it is better to use four-stage flash evaporation for the gray water treatment process, in which high-pressure flash evaporation separates the gasifier black water and the carbon washing tower black water, and the clarification tank settles and the vacuum filter separates the fine residue. 47) Regarding the oxygen flow adjustment problem of the four-nozzle gasifier, is it better to operate in cascade or self-adjusting? The oxygen flow and coal-water slurry flow adjustment is a double-cross adjustment system with the oxygen-coal ratio setting coefficient as a given value. In theory, this adjustment system can meet the process requirements while ensuring that the gasifier is not oxygen-free. That is, when the load is increased, the coal-water slurry flow rate increases first, and the oxygen flow rate increases later. ； When reducing the load, the oxygen flow rate decreases first, then the coal-water slurry flow rate decreases. ； Ensure that the coal-water slurry "increases in the front and decreases in the back" to prevent the gasifier from over-oxygenation. According to general enterprise experience, the load of the gasifier does not change frequently, so it is possible to use single-loop adjustment for oxygen adjustment and coal-water slurry adjustment respectively. At this time, the oxygen-to-coal ratio needs to be determined manually. For example, when setting the coal-water slurry flow rate, calculate the oxygen flow given value based on the oxygen-to-coal ratio, and then adjust the oxygen flow rate. 48) For a four-burner gasifier, two burners are tripped. If joint operation is required, do you need to purge nitrogen? If necessary, how to purge the multi-nozzle gasifier? There are four pairs of burners in total. Each pair of burners functions as an interlocking system, and the two interlocking systems do not interfere with each other! One pair of burners tripped. Only this pair of burners tripped. Pass medium-pressure nitrogen for some protection. ； The other pair of burners works normally, and the gasifier only reduces the load. If it is not the burner, the burner that jumped out can be fed immediately. This is also the biggest advantage! 49) Use of coal-water slurry additives Coal-water slurry rheology is an important property that affects the atomization and combustion characteristics of coal-water slurry. High-quality coal-water slurry not only has a higher concentration, but also has a good shear thinning effect to ensure that the slurry has good pumping and atomization characteristics, thereby reducing the transportation energy consumption of coal-water slurry and improving the combustion efficiency of coal-water slurry. Since coal is hydrophobic, the main function of the additive is to improve the hydrophilicity of the coal surface, reduce the surface tension of coal water, fully moisten the coal particles and evenly disperse them in a small amount of water, improve the flow of coal water slurry, reduce the viscosity of coal water slurry, and at the same time keep the coal particles evenly dispersed in water for a long time. In coal-water slurry, different types of coal use different additives, and the amounts and methods of addition are also different. Additives usually include dispersants, stabilizers and other auxiliary chemicals. Dispersants and stabilizers are indispensable in the preparation of coal water slurry. The dispersant can promote the uniform dispersion of the dispersed phase in the dispersion medium, and its function is to reduce the viscosity. The mechanism of the dispersant can be considered from three aspects: wetting and dispersion, electrostatic repulsion dispersion, and steric hindrance and entropic repulsion dispersion. Most dispersants are surfactants, which are composed of a hydrophobic group and a hydrophilic group. After being dissolved in water, the hydrophilic group is attracted by water molecules, while the hydrophobic group is repelled by water molecules. As a result, the hydrophobic groups are discharged to the water surface and are oriented, extending the hydrophobic end into the gas phase and the hydrophilic end into the water. When the water contains hydrophobic substances such as pulverized coal, it will also be oriented and arranged on the surface of the pulverized coal, thereby dispersing the pulverized coal particles very well. Dispersants can significantly reduce the surface tension of water and improve the wettability of the coal particle surface. The role of the stabilizer is to ensure the stability of the coal-water slurry, that is, to ensure the uniform behavior of the coal-water slurry during storage and transportation. Coal water slurry is a coarsely dispersed system composed of solid and liquid phases. The force of Brownian motion of molecules, the van der Waals force between particles, and the electrostatic attraction between particles are not enough to prevent the precipitation of particles. The stabilizer can combine the dispersed particles in the coal-water slurry with other surrounding particles and water to form a weak but strong three-dimensional spatial structure. This spatial structure forms mechanical resistance to particle precipitation, thus ensuring the stability of the coal-water slurry. Usually, inorganic salts, polymeric organic compounds, etc. are used as stabilizers. At present, my country has successfully developed three types of chemicals that can change the surface properties of coal and promote better adsorption of additive molecules on the surface of pulverized coal, and are used as stabilizers in the preparation of coal-water slurry. 50) What is the most important role of high-pressure nitrogen during coal-water slurry gasification? Is it as thermal azo protection for gasifiers? 1. Used as a purge of coal slurry and oxygen pipelines 2. As sealing nitrogen 3. As soot blowing gas for gasifier pressure lines. High-pressure nitrogen refers to: Nitrogen gas with a pressure of 12MPa. During normal production, 1. The furnace head pressure pipe removes nitrogen to blow away the ash and slag brought out by the gasification furnace, and at the same time has a cooling effect. ； 2. The temperature measurement point is used to protect the thermocouple. ； 3. It is used to purge the oxygen and coal slurry pipelines during startup and shutdown, and to purge the gas in the furnace, and at the same time partially replace the gasifier. ； 4. When the gasifier is stopped, part of it is used to isolate oxygen to prevent danger due to leakage. Also, before oxygen is introduced, the partially decompressed (6.5MPa) nitrogen plays a role in diluting the oxygen, but this is not high-pressure nitrogen. Furthermore, high-pressure nitrogen is not used for replacement after the system is shut down. At this time, the pressure of nitrogen is basically 5.9MPa. 51) What is the design outlet temperature of the carbon scrubber of the Texaco coal-water slurry 2.8-meter gasifier under 6.5MPa pressure? What is the outlet temperature of the carbon scrubber during actual operation? What operating factors are related to the outlet temperature of the gasifier? The temperature of the syngas from the gasification device of the 6.5MPa gasifier is generally around 240 degrees, and the water-vapor ratio is about 1.4. After the crude gas from the gasification device of the 6.5MPa gasifier is washed and dusted in the venturi scrubber and the scrubber tower, the temperature is about 241.9°C, the pressure is 6.28MPa (G), and the water vapor/dry gas is about 1.5 and is sent to the conversion process. At 6.5MPa, the process gas has been fully moistened and heat exchanged, and the temperature of the process gas in the carbon washing tower is about 243°C, reaching the saturated vapor pressure of water. At this time, the water-vapor ratio should be around 1.4. If the amount of quenching water is insufficient, the temperature of the process gas coming out of the gasifier is high and it may contain more water. The water vapor ratio is theoretically 1.4, but in fact it can reach up to 1.2. The main reason should be that most manufacturers open the quenching water volume much larger than the designed value. In order to prevent the quenching ring from burning out, most of the heat of the syngas is transferred to the black water system, causing a lot of steam to come out of the deoxidation tank and the clarifying tank, and the mud cannot settle. 52) What is the function of the balance hole in the downcomer of the gasifier? What is the difference if it is required or not? The balance hole can form a vortex, so that the slag accumulated on the bubble breaking strip is washed down. The initial design idea should be to reduce the generation of large slag by relying on the swirling effect after canceling the slag breaking machine. However, I personally feel that under the conditions of the quench chamber, there will not be much pressure difference between the inside and outside of the downcomer, and it may be difficult to form a high-speed swirling flow. I personally feel that these four holes are useless. 53) Can the burner valve of the oxygen pipe be cancelled? Mainly for safety reasons, some manufacturers still use manual valves for the oxygen inlet and chemical section valves, which are opened manually on site. I personally think it is very dangerous. The oxygen tube burner valve can be considered to be canceled due to the following reasons:: 1. Open the nitrogen filling valve after parking ； 2. The formation of nitrogen plug between the two oxygen cut-off valves ； 3. After the oxygen tube is cut twice, a small flow of nitrogen is blown. The system pressure has been released to normal pressure, and the burner has been removed after nitrogen replacement. The presence or absence of the burner valve actually does not have much impact. 54) What role do the pins on the inner wall of the gasifier play in preventing slag hanging? The size, arrangement and angle of the pins have an impact on the degree of slag hanging. Can improvements in the pin arrangement lead to better slag hanging effects? There are many pins planted on the outer wall of the water-cooled wall tube, which serve two purposes:: 1. Fixed refractory lining. 2. Remove the heat conduction water wall tube on the surface of the refractory lining in time to achieve the constant temperature effect of the refractory lining (the thermal conductivity of the refractory lining is generally only 1/5 of the metal pin). The technological characteristic of the shell is to use slag to resist slag. Slag nails are generally more than 10 centimeters long and are used to hang slag. During operation, the fluidity of the slag must be controlled. If the temperature is too high, the increased fluidity of the slag will reduce the thickness of the slag (if too much limestone will increase the viscosity of the slag), the slag nails will be exposed and burned out. If the temperature is too low, the conversion rate of carbon in the gasification reaction will decrease. 55) When Shell adds coal to the gasifier when the pressure rises to 1MPa, does it add coal after establishing a certain pressure? Is the furnace pressure fluctuation small? Why choose the point of 1MPa? It still has a lot to do with the compressor. 1. Mainly considering the need for sufficient quenching gas volume to cool the molten fly ash produced after coal is added. 2. Shell's chilling compressor adopts a single-stage cantilever type, which has a large axial thrust at low pressure and should generally be started under pressure. There is a reason why similar domestically produced imitation machines cannot solve the problem well and have to start at low pressure or normal pressure as a last resort. 3. According to the performance curve of the quench compressor, it should be above 0.6Mpa and generally in the range of 0.8 to 1.2Mpa. Its measurement can meet the basic quenching air volume required when adding coal. 4. If the SUB can be raised to 2.0Mpa or higher, coal can be added at that time. At this time, the pulverized coal transportation is more stable, the furnace pressure is more stable, and the requirements for the SUB are higher. 5. If you want to add coal at a lower pressure such as 0.8Mpa, the pulverized coal transportation at this time can also meet the requirements. If you want to throw coal at low pressure, the general situation is that the SUB is not fully debugged - lack of confidence - rush to throw - in case the SUB fails, but the intensity of the operation will * * Increase, a lot of inspections and preparations need to be done in a short period of time. 6. In summary, for the above reasons, it is more appropriate to add coal at 0.8 to 1.2Mpa, generally 1.0Mpa.