Pulverized coal fluidized bed gasifier with fly ash regasification function and operation method

Abstract

The invention discloses a pulverized coal fluidized bed gasification furnace with a fly ash regasification function and an operation method, and relates to a pulverized coal fluidized bed gasification furnace and an operation method. The invention aims to solve the problems of high specific coal consumption and low carbon conversion rate of the gasification furnace caused by over-high carbon content of fly ash and high-temperature slagging on the wall surface caused by over-high gasification temperature in the gasification furnace in the prior art. After the device is adopted, fly ash particles with all particle sizes entering the cyclone separator can be finally circulated back to the gasification furnace for regasification, and the fly ash particles with the carbon content not meeting the requirement can be repeatedly and circularly gasified in the device until the carbon content of the fly ash meets the requirement. And particles with small particle sizes are easy to fully contact with high-temperature flames, so that the specific coal consumption of the pulverized coal gasification furnace is reduced, the carbon conversion rate is improved, the emission of carbon dioxide is reduced, the coal saving effect is achieved, and the carbon content of discharged fly ash is reduced to be less than 10%. The invention belongs to the technical field of fluidized bed gasifiers.

Description

Technical Field

[0001] The present invention relates to a pulverized coal fluidized bed gasifier and an operating method, in particular to a pulverized coal fluidized bed gasifier with a fly ash regasification function and an operating method, belonging to the technical field of fluidized bed gasifiers. Background Art

[0002] Coal still holds an absolute dominant position in my country's current energy structure. By 2024, China's raw coal production was expected to reach 4.78 billion tons, 75% of which was used for power generation in power plant boilers and coal-fired power generation and heating. However, direct coal combustion leads to energy waste and environmental pollution. Therefore, the development of coal gasification technology is essential. Coal gasification is a highly efficient and clean coal technology. Current coal gasification technologies are mainly categorized into four types: moving bed gasification, fluidized bed gasification, entrained flow gasification, and molten bed gasification.

[0003] The Ende gasifier is one of the most representative circulating fluidized bed gasifiers, with the advantages of a wide range of raw coal applications, low production costs, strong cleaning capabilities, and little environmental pollution.

[0004] like Figure 1 As shown, the Ende gasifier also has the following defects in use:

[0005] 1. The pressure at the bottom of the gasifier is greater than the pressure in the discharge pipe, and the gas in the furnace flows back into the discharge pipe, causing most of the fly ash particles to be unable to return smoothly from the discharge pipe to the bottom of the gasifier, resulting in incomplete gasification reaction.

[0006] Second, the circulating material only relies on the natural return through the discharge channel under the action of gravity, and the return effect is poor, resulting in a large amount of fly ash in the synthesis gas generated during the operation of the gasifier. The carbon content of the fly ash is relatively high (30% to 40%), affecting the stable operation of the gasification system.

[0007] To address the above issues, the invention patent with announcement number CN103965968B proposes an Ende pulverized coal gasifier with a steam booster device, which effectively solves the main problem of high carbon content in fly ash during the operation of the Ende pulverized coal gasifier, resulting in high specific coal consumption and low carbon conversion rate of the gasifier. By introducing more fly ash particles into the gasifier for re-gasification, the combustible content of the fly ash is reduced.

[0008] However, in actual engineering applications, the steam ejection unit of the above-mentioned patent can only eject 90% of the fly ash particles with a particle size greater than 20 μm separated by the cyclone separator; while the remaining 10% of the fly ash particles with a particle size greater than 20 μm and the fly ash particles with a particle size less than 20 μm flow out from the gas phase outlet of the cyclone separator 7 along with the coal gas. This part of the fly ash particles cannot return to the furnace, resulting in the carbon content of the fly ash in the discharged coal gas reaching 20% ​​to 30%, which further leads to a high specific coal consumption and a low carbon conversion rate of the gasifier.

[0009] At the same time, the recycled materials participating in the combustion are also reduced accordingly. The insufficient concentration of fly ash particles in the furnace leads to a decrease in the gas-solid mixing efficiency. The air flow velocity in the local area is too low, and the particle residence time is shortened, which increases the furnace temperature and causes the high-temperature slag to adhere to the furnace wall, accelerating the adhesion of the slag to the furnace wall.

[0010] In summary, how to propose a new pulverized coal fluidized bed gasification furnace and operation method to address the above technical issues has become an urgent problem to be solved by technicians in this field. Summary of the Invention

[0011] In view of the above-mentioned deficiencies in the prior art, the present invention provides a pulverized coal fluidized bed gasifier with a fly ash regasification function.

[0012] The technical solution of the present invention is: a pulverized coal fluidized bed gasifier with a fly ash regasification function, comprising a gasifier, a cyclone separator and a steam ejector.

[0013] The conical cylinder wall at the lower part of the gasifier is provided with a gasifier pressure measuring hole, a pulverized coal inlet and a gasifying agent inlet from top to bottom; the outlet at the top of the gasifier is connected to the feed port on the side wall of the cyclone separator, and the discharge port at the bottom of the cyclone separator is connected to the conical cylinder at the lower part of the gasifier through the first discharge channel, and the steam ejector is connected to the first discharge channel. The pressure in the first discharge channel is greater than the pressure in the gasifier.

[0014] Furthermore, it also includes a heat exchange and dust removal unit and a return material storage hopper.

[0015] The heat exchange and dust removal unit includes an economizer, a gas holder and a bag dust collector.

[0016] The inlet of the economizer is connected to the gas phase outlet on the top of the cyclone separator, the outlet of the economizer is connected to the air inlet of the bag dust collector, and the gas cabinet is connected to the gas phase outlet of the bag dust collector.

[0017] An inert gas supply unit is installed on the top of the return material storage hopper. The inlet of the return material storage hopper is connected to the solid phase outlet of the bag dust collector. The outlet of the return material storage hopper is connected to the gasifier through the second discharge channel. A regulating valve and a second stop valve are installed on the second discharge channel.

[0018] An ash discharge pipe is installed on the conical cylinder wall at the lower part of the return material storage hopper, and a first stop valve and a second air pump are installed on the ash discharge pipe.

[0019] Furthermore, the inert gas supply unit includes a breathing valve, a nitrogen supply valve, a pressure gauge, a nitrogen storage tank and a nitrogen pressure relief valve.

[0020] The breathing valve, nitrogen storage tank and nitrogen pressure relief valve are all installed on the top of the return material storage hopper, and a nitrogen supply valve and a pressure gauge are installed on the pipeline connecting the nitrogen storage tank and the return material storage hopper.

[0021] Furthermore, a fly ash online carbon measuring instrument is installed on the conical cylinder wall at the lower part of the return material storage hopper.

[0022] Furthermore, a return hopper pressure measuring hole is opened on the side wall of the return material storage hopper.

[0023] Furthermore, a temperature sensor is installed on the cylinder wall of the gasifier.

[0024] The present invention also provides a method for operating a pulverized coal fluidized bed gasifier with a fly ash regasification function, which is specifically carried out in the following steps:

[0025] Step 1: Monitor the pressure P inside the return hopper through the return hopper pressure hole 21 , monitor the pressure P at the bottom of the gasifier through the gasifier pressure measuring hole 10 , ensure that P 21 =P 10 +(400~1000)Pa.

[0026] When P 21 <P 10 When the pressure is + (400~1000) Pa, the nitrogen pressure relief valve is closed, the nitrogen supply valve is opened, and nitrogen is filled into the return material storage hopper. At the same time, the pressure at the outlet of the nitrogen supply valve is monitored by a pressure gauge to keep the pressure between 0.2MPa~0.8MPa.

[0027] When P 21 >P 10 When the pressure is + (400~1000) Pa, the nitrogen supply valve is closed, the nitrogen pressure relief valve is opened, and the nitrogen in the return material storage hopper is discharged.

[0028] Step 2: Monitor the temperature in the gasifier through a temperature sensor.

[0029] When the furnace temperature is lower than 950℃, close the regulating valve to prevent the fly ash in the return material storage hopper from entering the gasifier;

[0030] When the furnace temperature is higher than 1050℃, the opening B of the regulating valve is maintained at 0%<B≤25%, and the flow rate Q of fly ash transported to the gasifier from the second discharge channel is set to 0t / h<Q≤5t / h, thereby controlling the furnace temperature to be stable at 950℃~1050℃;

[0031] When the furnace temperature is higher than 1100℃, the opening B of the regulating valve is maintained at 25%<B≤50%, and the flow rate Q of fly ash transported from the second discharge channel to the gasifier is 5t / h<Q≤10t / h, thereby controlling the furnace temperature to be stable at 950℃~1050℃;

[0032] When the furnace temperature is higher than 1150℃, the opening B of the regulating valve is maintained at 50%<B≤75%, and the flow rate Q of fly ash transported from the second discharge channel to the gasifier is set to 10t / h<Q≤15t / h, thereby controlling the furnace temperature to be stable at 950℃~1050℃;

[0033] When the furnace temperature is higher than 1200℃, the opening B of the regulating valve is maintained at 75%<B≤100%, and the flow rate Q of fly ash transported to the gasifier from the second discharge channel is 15t / h<Q≤20t / h, thereby controlling the furnace temperature to be stable at 950℃~1050℃.

[0034] Step 3: Measure the carbon content of fly ash in the return material storage hopper using the fly ash online carbon measuring instrument 29 ;

[0035] When 29 When the concentration is ≤10%, close the second stop valve, open the first stop valve, and discharge the fly ash into the return material storage hopper through the second air pump and the ash discharge pipe;

[0036] When 29 When the temperature is greater than 10%, the first stop valve is closed and the second stop valve is opened to allow the fly ash to enter the gasifier again through the second discharge channel for circulation and gasification.

[0037] Compared with the prior art, the present invention has the following effects:

[0038] 1. The carbon content of the fly ash discharged through the ash discharge pipe 22 is reduced, the amount of ash circulating back to the gasifier 10 is increased, the specific coal consumption of the gasifier 10 is reduced, and the carbon conversion rate is improved.

[0039] After adopting the present invention, the coal gas generated in the gasifier 10 carries fly ash particles into the cyclone separator 7, among which fly ash particles with a particle size greater than 20 μm enter the lower part of the gasifier 10 through the first discharge channel 5, and the remaining fly ash particles enter the economizer 11 with the coal gas for heat exchange. The low-temperature gas-solid two-phase mixture is separated from the fly ash particles by the bag dust collector 13, and then enters the return material storage hopper 21. Finally, the carbon content of the fly ash is detected by the fly ash online carbon meter 29, and the fly ash with a carbon content less than or equal to 10% is discharged from the ash discharge pipe 22. The fly ash with a carbon content greater than 10% is controlled by the regulating valve 24 to enter the gasifier 10 times for more than ten cycles to participate in gasification.

[0040] Therefore, after adopting the present invention, fly ash particles of all sizes entering the cyclone separator 7 can ultimately be recycled back to the gasifier 10 for regasification. Fly ash particles that do not meet the required carbon content can be repeatedly recycled and gasified in the present invention until the fly ash carbon content meets the required carbon content. The phenomenon of fly ash particles with small particle size and excessively high carbon content being directly discharged from the system will not occur. Small particles easily come into contact with the high-temperature flame, which facilitates the complete combustion of combustible materials, allowing the residual carbon in the fly ash to further burn and release coal gas in the gasifier. This not only reduces the specific coal consumption of the pulverized coal gasifier, improves the carbon conversion rate, and reduces carbon dioxide emissions, thus achieving the effect of saving coal, but also reduces the carbon content of the discharged fly ash to less than 10%, which is significantly lower than that of the prior art. This makes the present invention widely applicable in the production of chemical synthesis or fuel oil synthesis feed gas, industrial gas, domestic gas, metallurgical reducing gas, and combined cycle power generation gas.

[0041] 2. Effectively adjust the gasification temperature of the gasifier 10 during operation to prevent high-temperature slagging in the gasifier 10:

[0042] A temperature sensor 30 is installed on the gasifier 10 to measure the temperature inside the furnace. A regulating valve 24 is installed on the second discharge channel 25 to control the flow rate of circulating fly ash entering the gasifier 10. The flow rate of fly ash entering the gasifier 10 through the second discharge channel 25 ranges from 0 t / h to 20 t / h, so that the gasification temperature of the gasifier is stabilized at 950°C to 1050°C.

[0043] When fly ash particles enter the gasifier 10 through the second feed channel 25 and participate in gasification again, the high-temperature pyrolysis and gasification of the pulverized coal absorbs heat, lowering the temperature within the gasifier 10. Therefore, with the present invention, the temperature within the gasifier 10 can be effectively controlled, preventing a sudden temperature rise in the gasifier 10 when too little feed is returned, which could lead to the formation of high-temperature molten slag within the gasifier 10. This effectively prevents slagging on the walls of the gasifier 10.

[0044] 3. The inert gas supply unit ensures the safety of the return material storage hopper 21:

[0045] Nitrogen pressure relief valve 19 discharges nitrogen from return hopper 21. Pressure gauge 17 measures the outlet pressure of nitrogen supply valve 16. Breathing valve 15 automatically regulates the pressure inside return hopper 21, rapidly adjusting the internal pressure and preventing overpressure accidents caused by abnormal internal pressure (such as sudden increases or decreases). Supplying nitrogen into return hopper 21 isolates oxygen, preventing oxidation of fly ash particles, and water vapor, preventing moisture, thereby ensuring the seal of return hopper 21.

[0046] 4. The material flow in the second discharge channel 25 is stable and gas backflow will not occur:

[0047] The return hopper pressure gauge 20 monitors the pressure inside the return storage hopper 21, while the gasifier pressure gauge 27 monitors the pressure inside the gasifier 10. By supplying nitrogen into the return storage hopper 21, the pressure inside the return storage hopper 21 is kept 400 Pa to 1000 Pa higher than the pressure inside the gasifier 10. This prevents coal gas from the bottom of the gasifier 10 from flowing into the second discharge channel 25. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram showing defects of the Ende gasifier in the prior art;

[0049] Figure 2 It is a schematic diagram of the present invention.

[0050] In the figure: 1. Gasifying agent inlet; 2. Pulverized coal inlet; 3. Steam ejector; 5. First discharge channel; 7. Cyclone separator; 10. Gasifier; 11. Economizer; 12. Gas cabinet; 13. Bag filter; 14. First air pump; 15. Breathing valve; 16. Nitrogen supply valve; 17. Pressure gauge; 18. Nitrogen storage tank; 19. Nitrogen pressure relief valve; 20. Return hopper pressure measuring hole; 21. Return material storage hopper; 22. Ash discharge pipe; 23. First stop valve; 24. Regulating valve; 25. Second discharge channel; 26. Second stop valve; 27. Gasifier pressure measuring hole; 28. Second air pump; 29. ​​Fly ash online carbon analyzer; 30. Temperature sensor. DETAILED DESCRIPTION

[0051] In order to make the objects, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0052] Specific implementation method 1: Combination Figure 2 The present embodiment is described below. A pulverized coal fluidized bed gasifier with a fly ash regasification function includes a gasifier 10 , a cyclone separator 7 , and a steam ejector 3 .

[0053] The conical wall at the bottom of the gasifier 10 is provided with a gasifier pressure gauge 27, a pulverized coal inlet 2, and a gasifying agent inlet 1, sequentially from top to bottom. The gasifier pressure gauge 27 is used to measure the pressure at the bottom of the gasifier 10. The outlet at the top of the gasifier 10 communicates with the feed port on the side wall of the cyclone separator 7. The discharge port at the bottom of the cyclone separator 7 communicates with the conical wall at the bottom of the gasifier 10 via the first discharge channel 5. The steam ejector 3 communicates with the first discharge channel 5. The pressure within the first discharge channel 5 is greater than the pressure within the gasifier 10. This arrangement ensures that the direction of the airflow within the first discharge channel 5 remains unchanged. The airflow within the first discharge channel 5 is blown from the discharge port of the cyclone separator 7 toward the gasifier 10. The airflow carries fly ash with a particle size greater than 20 μm from the cyclone separator 7 through the first discharge channel 5 and flows into the bottom of the gasifier 10, increasing the fly ash circulation rate.

[0054] Furthermore, it also includes a heat exchange and dust removal unit and a return material storage hopper 21.

[0055] The heat exchange and dust removal unit includes an economizer 11 , a gas holder 12 and a bag filter 13 .

[0056] The inlet of the economizer 11 is connected to the gas phase outlet at the top of the cyclone separator 7. With this arrangement, fly ash with a particle size of less than 20 μm enters the economizer 11 along with the synthesis gas for heat exchange. The outlet of the economizer 11 is connected to the air inlet of the bag-type dust collector 13, and the gas cabinet 12 is connected to the gas phase outlet of the bag-type dust collector 13.

[0057] An inert gas supply unit is installed on the top of the return material storage hopper 21. The inlet of the return material storage hopper 21 is connected to the solid phase outlet of the bag dust collector 13. The outlet of the return material storage hopper 21 is connected to the gasifier 10 through the second discharge channel 25. The second discharge channel 25 is installed with a regulating valve 24 and a second stop valve 26.

[0058] An ash discharge pipe 22 is installed on the conical cylinder wall at the lower part of the return material storage hopper 21 , and a first stop valve 23 and a second air pump 28 are installed on the ash discharge pipe 22 .

[0059] Specific implementation method 2: Combination Figure 2 To describe this embodiment, the inert gas supply unit includes a breathing valve 15 , a nitrogen supply valve 16 , a pressure gauge 17 , a nitrogen storage tank 18 and a nitrogen pressure relief valve 19 .

[0060] The breathing valve 15 , nitrogen storage tank 18 and nitrogen pressure relief valve 19 are all installed on the top of the return material storage hopper 21 , and a nitrogen supply valve 16 and a pressure gauge 17 are installed on the pipeline connecting the nitrogen storage tank 18 and the return material storage hopper 21 .

[0061] In this embodiment, the inert gas supply unit ensures the safety of the return material storage hopper 21: the nitrogen pressure relief valve 19 is used to discharge the nitrogen from the return material storage hopper 21, the pressure gauge 17 is used to measure the outlet pressure of the nitrogen supply valve 16, and the breathing valve 15 is used to automatically adjust the pressure inside the return material storage hopper 21, so as to quickly adjust the internal pressure and prevent overpressure accidents caused by abnormal internal pressure (such as sudden increase or sudden decrease).

[0062] Other components and connection relationships are the same as those in the first embodiment.

[0063] Specific implementation method three: Combination Figure 2 In the present embodiment, the regulating valve 24 is a throttle valve.

[0064] Furthermore, the second discharge channel 25 is a pipeline for transporting 0 to 20 tons of fly ash per hour.

[0065] Furthermore, the gasifier 10 is an Ende pulverized coal gasifier with a furnace temperature of 950°C to 1050°C.

[0066] Other components and connection relationships are the same as those in the first or second embodiment.

[0067] Specific implementation method four: Combination Figure 2 To illustrate this embodiment, in this embodiment, a fly ash online carbon measuring instrument 29 is installed on the conical cylinder wall at the lower part of the return material storage hopper 21, and the fly ash online carbon measuring instrument 29 is arranged above the ash discharge pipe 22.

[0068] Furthermore, a return hopper pressure measuring hole 20 is opened on the side wall of the return material storage hopper 21. Such an arrangement facilitates the measurement of the pressure inside the return material storage hopper 21.

[0069] Furthermore, a temperature sensor 30 is installed on the cylinder wall of the gasifier 10 . This arrangement facilitates measuring the temperature inside the gasifier 10 .

[0070] Furthermore, a first air pump 14 is installed on the pipeline connecting the return material storage hopper 21 and the bag filter 13 . This arrangement facilitates the injection of fly ash particles with a particle size of less than 20 μm into the return material storage hopper 21 .

[0071] Other components and connection relationships are the same as those in the first, second or third embodiment.

[0072] Specific implementation method five: Combination Figure 2 The present embodiment describes a method for operating a pulverized coal fluidized bed gasifier with a fly ash regasification function, which is carried out in the following steps: Step 1: monitor the pressure P inside the return hopper 21 through the return hopper pressure measuring hole 20. 21 The pressure P at the bottom of the gasifier 10 is monitored through the gasifier pressure measuring hole 27. 10, ensure that P 21 =P 10 +(400~1000)Pa.

[0073] When P 21 <P 10 When the pressure is + (400~1000) Pa, the nitrogen pressure relief valve 19 is closed, the nitrogen supply valve 16 is opened, and nitrogen is filled into the return material storage hopper 21. At the same time, the pressure at the outlet of the nitrogen supply valve 16 is monitored by the pressure gauge 17 to maintain the pressure between 0.2MPa and 0.8MPa.

[0074] When P 21 >P 10 When the pressure reaches +(400-1000) Pa, the nitrogen supply valve 16 closes, and the nitrogen pressure relief valve 19 opens to discharge the nitrogen from the return hopper 21. This arrangement prevents the coal gas in the gasifier 10 from flowing into the second discharge channel 25, ensuring that the flow direction within the second discharge channel 25 remains unchanged. This, on the one hand, facilitates the safe operation of the return hopper 21, and on the other hand, facilitates the transport of fly ash from the return hopper 21 to the gasifier 10. Once in the gasifier 10, the fly ash absorbs heat and vaporizes again, lowering the operating temperature within the furnace and preventing slagging at high temperatures.

[0075] Step 2: Monitor the temperature inside the gasifier 10 through the temperature sensor 30.

[0076] When the furnace temperature is lower than 950° C., the regulating valve 24 is closed to prevent the fly ash in the return material storage hopper 21 from entering the gasifier 10 .

[0077] When the furnace temperature is higher than 1050°C, the opening B of the regulating valve 24 is maintained at 0%<B≤25%, and the flow rate Q of fly ash transported from the second discharge channel 25 to the gasifier 10 is set to 0t / h<Q≤5t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C.

[0078] When the furnace temperature is higher than 1100°C, the opening B of the regulating valve 24 is maintained at 25%<B≤50%, and the flow rate Q of fly ash transported from the second discharge channel 25 to the gasifier 10 is 5t / h<Q≤10t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C.

[0079] When the furnace temperature is higher than 1150°C, the opening B of the regulating valve 24 is maintained at 50%<B≤75%, and the flow rate Q of fly ash transported from the second discharge channel 25 to the gasifier 10 is set to 10t / h<Q≤15t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C.

[0080] When the furnace temperature is higher than 1200°C, the opening B of the regulating valve 24 is maintained at 75%<B≤100%, and the flow rate Q of fly ash transported to the gasifier 10 by the second discharge channel 25 is 15t / h<Q≤20t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C. In this setting, the flow rate of fly ash entering the gasifier 10 is controlled by changing the opening B of the regulating valve 24, thereby adjusting the gasification temperature in the furnace and preventing high-temperature slagging in the furnace.

[0081] Step 3: Measure the carbon content of fly ash in the return material storage hopper 21 by using the fly ash online carbon measuring instrument 29. 29 ;

[0082] When 29 When the concentration is less than or equal to 10%, the second stop valve 26 is closed, the first stop valve 23 is opened, and the fly ash is discharged from the return material storage hopper 21 through the second air pump 28 and the ash discharge pipe 22;

[0083] When 29 When the carbon content of the fly ash is greater than 10%, the first stop valve 23 is closed and the second stop valve 26 is opened to allow the fly ash to re-enter the gasifier 10 through the second discharge channel 25 for circulation and gasification. This arrangement can not only prevent excessive accumulation of fly ash in the return material storage hopper 21, but also effectively reduce the carbon content of the fly ash, thereby improving the working efficiency of the gasifier 10.

[0084] Other components and connection relationships are the same as those in the first, second, third or fourth embodiment.

[0085] Example

[0086] A coal chemical company uses a gas production capacity design value of 20000Nm 3 The Ende pulverized coal gasifier, which produces coal gas at a rate of approximately 8,000 hours per year, operates at a rate of 3 tons of ash per hour, with a carbon content of 35%. Temperature sensors indicate that the gasification temperature in the furnace remains around 1,200°C for extended periods, leading to a buildup of high-temperature slag on the walls. The furnace needs to be shut down and started three times per year for maintenance and slag cleaning. The resulting production losses, venting costs, and maintenance expenses total approximately 4.2 million yuan.

[0087] After adopting the present invention, the fly ash online carbon measuring instrument 29 detects the carbon content of the fly ash in real time. When the carbon content of the fly ash entering the return material storage hopper 21 is greater than 10%, the first stop valve 23 on the ash discharge pipe 22 is closed, and no ash is discharged. The regulating valve 24 on the second discharge channel 25 is opened, so that the fly ash particles with a carbon content greater than 10% are repeatedly returned to the gasifier for gasification until the fly ash online carbon measuring instrument 29 measures the carbon content of the fly ash to be reduced to 10% or below. The regulating valve 24 is closed and the first stop valve 23 is opened for ash discharge. Finally, the gasifier operates stably, producing 2.167 tons of ash per hour, the carbon content of the fly ash is about 10%, and the amount of coal saved per hour is 1.241 tons.

[0088] When the gasification temperature in the gasifier reaches or exceeds 1200°C, the regulating valve 24 is fully opened to control the fly ash flow rate entering the gasifier through the second discharge channel 25 to 20 t / h;

[0089] When the gasification temperature in the gasifier drops to 1150° C., the opening of the regulating valve 24 is adjusted to 75%, and the flow rate of fly ash entering the gasifier through the second discharge channel 25 is controlled to be 15 t / h.

[0090] When the gasification temperature in the gasifier drops to 1100° C., the opening of the regulating valve 24 is adjusted to 50%, and the flow rate of fly ash entering the gasifier through the second discharge channel 25 is controlled to be 10 t / h.

[0091] When the gasification temperature in the gasifier is reduced to 1050° C., the opening of the regulating valve 24 is adjusted to 25%, and the flow rate of fly ash entering the gasifier through the second discharge channel 25 is controlled to be 5 t / h.

[0092] When the gasification temperature in the gasifier drops to 950° C., the regulating valve 24 is closed to prevent the fly ash from entering the gasifier. Finally, the temperature sensor 30 measures that the gasification temperature in the gasifier remains at around 950° C. for a long time.

[0093] The present invention effectively solves the problems of high carbon content in fly ash during the operation of the gasifier, resulting in high specific coal consumption and low carbon conversion rate of the gasifier. At the same time, the wall temperature is reduced, and high-temperature slagging is effectively controlled. There is no need to start and stop the furnace for slagging. The annual coal consumption and start-up and shutdown costs saved are approximately 12.14 million yuan.

[0094] How it works

[0095] Pulverized coal enters gasifier 10 through pulverized coal inlet 2. A gasifying agent consisting of air (or oxygen) and superheated steam is injected into gasifier 10 through gasifying agent inlet 1. The pulverized coal and gasifying agent mix and burn and gasify within gasifier 10. After combustion, smaller fly ash particles, along with the syngas, enter cyclone separator 7.

[0096] Fly ash particles larger than 20 μm are separated by cyclone separator 7 and enter first discharge channel 5. They then return to the bottom of gasifier 10 through the combined effects of steam ejector 3 and gravity, where they resume the gasification reaction. The remaining fly ash particles, along with the syngas, are transported through the gaseous phase outlet of cyclone separator 7 to economizer 11 for heat exchange. The low-temperature syngas and fly ash particles exiting economizer 11 enter baghouse 13. The fly ash separated from the syngas enters return material storage hopper 21 under the action of first air pump 14, and the separated syngas enters gas cabinet 12 for storage.

[0097] The internal pressure of the return material storage hopper 21 is measured through the return hopper pressure measuring hole 20. Nitrogen enters the return material storage hopper 21 from the nitrogen storage tank 18 through the nitrogen supply valve 16. The breathing valve 15 is used to automatically adjust the internal pressure. The pressure gauge 17 is used to measure the outlet pressure of the nitrogen supply valve 16.

[0098] The fly ash online carbon measuring instrument 29 detects the fly ash in the return material storage hopper 21. The fly ash with low carbon content enters the ash discharge pipe 22 and is discharged from the return material storage hopper 21 under the action of the first stop valve 23 and the second air pump 28; the fly ash with high carbon content enters the second discharge channel 25 and enters the gasifier 10 to participate in the gasification reaction again under the action of the second stop valve 26 and the regulating valve 24.

[0099] The present invention has been disclosed as above in terms of preferred embodiments, but this is not intended to limit the present invention. Any simple modifications, equivalent changes, and modifications made to the above implementation cases by any person skilled in the art without departing from the content of the technical solution of the present invention based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A pulverized coal fluidized bed gasifier with a fly ash regasification function, comprising a gasifier (10), a cyclone separator (7) and a steam ejector (3); The conical cylinder wall at the lower part of the gasifier (10) is provided with a gasifier pressure measuring hole (27), a pulverized coal inlet (2) and a gasifying agent inlet (1) in sequence from top to bottom; the outlet at the top of the gasifier (10) is connected to the feed port on the side wall of the cyclone separator (7); the discharge port at the bottom of the cyclone separator (7) is connected to the conical cylinder at the lower part of the gasifier (10) through the first discharge channel (5); the steam ejector (3) is connected to the first discharge channel (5); and the pressure in the first discharge channel (5) is greater than the pressure in the gasifier (10); Its characteristics are: It also includes a heat exchange and dust removal unit and a return material storage hopper (21); The heat exchange and dust removal unit includes an economizer (11), a gas holder (12) and a bag dust collector (13); The inlet of the economizer (11) is connected to the gas phase outlet at the top of the cyclone separator (7), the outlet of the economizer (11) is connected to the air inlet of the bag dust collector (13), and the gas cabinet (12) is connected to the gas phase outlet of the bag dust collector (13); An inert gas supply unit is installed on the top of the return material storage hopper (21), the inlet of the return material storage hopper (21) is connected to the solid phase outlet of the bag dust collector (13), and the outlet of the return material storage hopper (21) is connected to the gasifier (10) through a second discharge channel (25), and a regulating valve (24) and a second stop valve (26) are installed on the second discharge channel (25); An ash discharge pipe (22) is installed on the conical cylinder wall at the lower part of the return material storage hopper (21), and a first stop valve (23) and a second air pump (28) are installed on the ash discharge pipe (22).

2. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 1, characterized in that: The inert gas supply unit includes a breathing valve (15), a nitrogen supply valve (16), a pressure gauge (17), a nitrogen storage tank (18) and a nitrogen pressure relief valve (19); The breathing valve (15), the nitrogen storage tank (18) and the nitrogen pressure relief valve (19) are all installed on the top of the return material storage hopper (21), and a nitrogen supply valve (16) and a pressure gauge (17) are installed on the pipeline connecting the nitrogen storage tank (18) and the return material storage hopper (21).

3. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 2, characterized in that: The regulating valve (24) is a throttle valve.

4. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 3, characterized in that: The second discharge channel (25) is a pipeline for transporting 0 to 20 tons of fly ash per hour.

5. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 4, characterized in that: The gasifier (10) is an Ende pulverized coal gasifier with a furnace temperature of 950°C to 1050°C.

6. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 5, characterized in that: A fly ash online carbon measuring instrument (29) is installed on the conical cylinder wall at the lower part of the return material storage hopper (21).

7. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 6, characterized in that: A return hopper pressure measuring hole (20) is provided on the side wall of the return material storage hopper (21).

8. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 7, characterized in that: A temperature sensor (30) is installed on the cylinder wall of the gasification furnace (10).

9. The pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 8, characterized in that: A first air pump (14) is installed on the pipeline connecting the return material storage hopper (21) and the bag dust collector (13).

10. An operating method using the pulverized coal fluidized bed gasifier with fly ash regasification function according to claim 9, characterized in that: The method is specifically carried out in the following steps: Step 1: Monitor the pressure P inside the return hopper (21) through the return hopper pressure measuring hole (20). 21 , monitor the pressure P at the bottom of the gasifier (10) through the gasifier pressure measuring hole (27) 10 , ensure that P 21 =P 10 + (400~1000) Pa; When P 21 <P 10 When the pressure is +(400~1000)Pa, the nitrogen pressure relief valve (19) is closed, the nitrogen supply valve (16) is opened, and nitrogen is filled into the return material storage hopper (21). At the same time, the pressure at the outlet of the nitrogen supply valve (16) is monitored by the pressure gauge (17) to keep the pressure between 0.2MPa~0.8MPa; When P 21 >P 10 When the pressure is +(400~1000)Pa, the nitrogen supply valve (16) is closed, and the nitrogen pressure relief valve (19) is opened to discharge the nitrogen in the return material storage hopper (21); Step 2: monitoring the temperature in the gasification furnace (10) through a temperature sensor (30); When the furnace temperature is lower than 950° C., the regulating valve (24) is closed to prevent the fly ash in the return material storage hopper (21) from entering the gasifier (10); When the furnace temperature is higher than 1050°C, the opening B of the regulating valve (24) is maintained at 0%<B≤25%, and the flow rate Q of the fly ash transported from the second discharge channel (25) to the gasifier (10) is set to 0t / h<Q≤5t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C; When the furnace temperature is higher than 1100°C, the opening B of the regulating valve (24) is maintained at 25%<B≤50%, and the flow rate Q of the fly ash transported from the second discharge channel (25) to the gasifier (10) is set to 5t / h<Q≤10t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C; When the furnace temperature is higher than 1150°C, the opening B of the regulating valve (24) is maintained at 50%<B≤75%, and the flow rate Q of the fly ash transported from the second discharge channel (25) to the gasifier (10) is set to 10t / h<Q≤15t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C; When the furnace temperature is higher than 1200°C, the opening B of the regulating valve (24) is maintained at 75%<B≤100%, and the flow rate Q of the fly ash transported from the second discharge channel (25) to the gasifier (10) is set to 15t / h<Q≤20t / h, thereby controlling the furnace temperature to be stable at 950°C~1050°C; Step 3: Measure the carbon content of fly ash in the return material storage hopper (21) using the fly ash online carbon measuring instrument (29). 29 ; When 29 When the content is less than or equal to 10%, the second stop valve (26) is closed, the first stop valve (23) is opened, and the fly ash is discharged from the return material storage hopper (21) through the second air pump (28) and the ash discharge pipe (22); When 29 When the temperature is greater than 10%, the first stop valve (23) is closed and the second stop valve (26) is opened, so that the fly ash enters the gasifier (10) again through the second discharge channel (25) for circulation and gasification.

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