Circulating fluidized bed activation furnace system and working method

Abstract

The invention discloses a circulating fluidized bed activation furnace system and a working method. The system comprises an adiabatic circulating fluidized bed boiler, a cyclone separator, a smoke aftercombustion chamber and a waste heat boiler. A feeding port of the adiabatic circulating fluidized bed boiler is connected with a material returning device below the cyclone separator through a dipleg, and a smoke outlet of the adiabatic circulating fluidized bed boiler is sequentially connected with the cyclone separator, a smoke post-combustion chamber and the waste heat boiler through pipelines. Coal is preheated in a dipleg by changing the position of a coal feeding device, the fluidization air volume can be reduced, the fluidization condition of the coal in a fluidized bed is improved, and heat generated by coal pyrolysis is recycled by arranging a smoke aftercombustion chamber and a waste heat boiler; the interior of the hearth is divided into the pyrolysis area and the activation area by adjusting the shape and the air distribution mode of the air distribution plate, the temperature is adjusted by adjusting the oxygen content of the pyrolysis area and the activation area, and the whole system has the advantages of being low in energy consumption, sufficient in waste heat utilization, stable, capable of saving energy, environmentally friendly and the like.

Description

Technical Field

[0001] The invention relates to the technical field of circulating fluidized bed activation, and in particular to a circulating fluidized bed activation furnace system and a working method. Background Art

[0002] Activated carbon is an important basic chemical product and an important branch of new materials and carbon raw materials. It is a porous material with developed pores, high specific surface area and rich surface functional groups. It has the advantages of stable structure and easy preparation. It has been widely used in various fields such as environmental protection, chemical industry, food processing, drug refining, military chemical protection, etc.

[0003] Common activation processes for activated carbon include: physical activation method, by introducing activation gases, such as carbon dioxide, water vapor, air, etc., using these activation gases to corrode the carbonized material, so that a porous microcrystalline structure is formed on its surface, forming pores with a large specific surface area; chemical activation method, the raw materials and chemical activators are mixed and kneaded, and activated and carbonized at high temperature to produce activated carbon. Commonly used chemicals include zinc chloride, phosphoric acid, potassium sulfate, etc.; chemical-physical combined activation method, the above two processes are used for activated carbon activation at the same time, generally chemical activation first, and then physical activation.

[0004] Fluidized bed activation furnace can shorten the activation time to a considerable extent compared to fixed bed, and good gas-solid contact is conducive to the formation of mesopores. However, the existing circulating fluidized bed structure design is mainly based on complete combustion power generation, surrounded by water-cooled walls, with non-insulated heating surfaces arranged inside, a horizontal bottom structure, and no internal partitions. It is difficult to complete the processes of pyrolysis to produce semi-coke, activation to produce activated carbon, and gasification to produce synthesis gas at the same time. It has a single purpose and uniform distribution of fluidizing air. When the fluidized bed continuously produces activated carbon, the fluidized bed has problems such as poor product quality uniformity due to severe back mixing of solid particles and wide distribution of particle residence time, as well as poor energy utilization due to the inability to recycle the energy generated by coal pyrolysis. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a circulating fluidized bed activation furnace system and a working method. By changing the position of the coal feeding device, the coal is preheated in the material legs, which can reduce the fluidizing air volume and improve the fluidization of the coal in the fluidized bed. The heat generated by the pyrolysis of the coal is recovered by arranging a flue gas afterburner and a waste heat boiler. By adjusting the shape of the air distribution plate and the air distribution method, the interior of the furnace is divided into a pyrolysis zone and an activation zone. The temperature is adjusted by adjusting the oxygen content in the pyrolysis zone and the activation zone. The whole system has the advantages of low energy consumption, full utilization of waste heat, stable system, energy saving and environmental protection.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect of the present invention, a circulating fluidized bed activation furnace system is provided, comprising an adiabatic circulating fluidized bed boiler, a cyclone separator, a flue gas afterburner and a waste heat boiler; the feed inlet of the adiabatic circulating fluidized bed boiler is connected to a return feeder below the cyclone separator through a feed leg, and a coal feeding device is arranged on the feed leg; the flue gas outlet of the adiabatic circulating fluidized bed boiler is connected to the cyclone separator, the flue gas afterburner and the waste heat boiler in sequence through a pipeline; a pyrolysis zone and an activation zone are arranged in the adiabatic circulating fluidized bed boiler; the bottom of the pyrolysis zone is connected to a primary air duct, and the bottom of the activation zone is connected to a steam pipe, a recycled flue gas duct and a primary air duct.

[0008] In some embodiments of the present invention, the flue gas aftercombustion chamber is connected to a heat exchanger, and a hot flue gas duct, a supplementary combustion air duct and a primary air duct pass through the inside of the heat exchanger. The hot flue gas duct serves as a hot fluid duct, and the supplementary combustion air duct and the primary air duct serve as cold fluid ducts.

[0009] In some embodiments of the present invention, the inlet of the hot flue gas duct is connected to the flue gas outlet of the flue gas aftercombustion chamber, and the outlet of the hot flue gas duct is connected to the recirculation flue gas duct through a flue gas fan; the outlet of the supplementary combustion air duct is connected to the flue gas aftercombustion chamber, and the inlet is connected to the supplementary combustion fan; the inlet of the primary air duct is connected to the blower, and the outlet is connected to the pyrolysis zone and the activation zone through multiple pipes.

[0010] In some embodiments of the present invention, the waste heat boiler is connected to a flue gas afterburner at the top, a cold flue gas duct is connected to the bottom of the waste heat boiler, and a steam duct is connected to the rear of the waste heat boiler.

[0011] In some embodiments of the present invention, the cold smoke duct is connected to a first cold smoke duct and a second cold smoke duct respectively, the first cold smoke duct is connected to a hot smoke duct, and the second cold smoke duct is connected to a smoke treatment device after passing through an induced draft fan.

[0012] In some embodiments of the present invention, the steam pipe is connected to a first steam pipe and a second steam pipe respectively, a steam valve is provided on the steam pipe, the outlet of the first steam pipe is connected to a return feeder, and the outlet of the second steam pipe is connected to an activation zone inside the adiabatic circulating fluidized bed boiler.

[0013] In some embodiments of the present invention, the bottom of the pyrolysis zone is arranged in an inclined manner, and the activation zone is arranged in a horizontal manner.

[0014] In some embodiments of the present invention, the outlet of the activation zone is connected to a cooler and a sorting silo in sequence through a carbon discharge pipe.

[0015] In some embodiments of the present invention, the flue gas inlet of the flue gas afterburner is communicated with the flue gas outlet of the cyclone separator.

[0016] In a second aspect of the present invention, a method for operating a circulating fluidized bed activation furnace system is provided, comprising the following steps:

[0017] The coal enters the feed leg through the coal feeding device and is preheated in the feed leg before entering the pyrolysis zone of the adiabatic circulating fluidized bed boiler. After pyrolysis, the coal is converted into semi-coke, and continues to move downward into the activation zone for activation. After activation, it continues to move downward and is discharged through the carbon discharge pipe.

[0018] The flue gas generated in the adiabatic circulating fluidized bed boiler enters the cyclone separator for gas-solid separation. The separated solids are returned to the adiabatic circulating fluidized bed boiler through the return feeder. The separated flue gas enters the flue gas afterburner for reburning. The flue gas generated by the reburning enters the waste heat boiler and the heat exchanger respectively. The waste heat boiler provides steam for the activation zone of the adiabatic circulating fluidized bed boiler. The hot flue gas after heat exchange in the heat exchanger and the cold flue gas generated by the waste heat boiler are mixed and provided to the activation zone of the adiabatic circulating fluidized bed boiler as recycled flue gas.

[0019] One or more technical solutions of the present invention have the following beneficial effects:

[0020] The present invention changes the position of the coal feeding device to preheat the coal in the material leg, thereby reducing the fluidizing air volume, improving the fluidization of the coal in the fluidized bed, and thus reducing the power consumption of the equipment; by arranging the primary air duct, the steam duct, and the recirculating flue gas duct at the bottom of the adiabatic circulating fluidized bed boiler, the flow ratio of each fluid is adjusted, and the oxygen content in the pyrolysis zone and the activation zone can be flexibly adjusted, thereby adjusting the temperature; by arranging the primary air duct, the steam duct, and the recirculating flue gas duct at the bottom of the adiabatic circulating fluidized bed boiler, the fluid flow at each point can be adjusted, and the pressure difference of the material layer at each point can be flexibly adjusted, thereby adjusting the particle residence time.

[0021] The circulating fluidized bed activation furnace system provided by the present invention utilizes a waste heat boiler and a heat exchanger to recover the heat of flue gas from a flue gas afterburner. By adjusting the shape of an air distribution plate and the air distribution method, the interior of the furnace is divided into a pyrolysis zone and an activation zone (a flue gas and air mixture is introduced into the pyrolysis zone, and a mixture of air and steam is introduced into the activation zone). The temperature is adjusted by adjusting the oxygen content in the pyrolysis zone and the activation zone. The entire system has the advantages of low energy consumption, full utilization of waste heat, stable system, energy saving and environmental protection, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a working principle diagram of the circulating fluidized bed activation furnace system of the present invention.

[0023] In the figure: 1. coal feeding device; 2. material leg; 3. pyrolysis zone; 4. activation zone; 5. adiabatic circulating fluidized bed boiler; 6. cyclone separator; 7. flue gas afterburner; 8. heat exchanger; 9. waste heat boiler; 10. flue gas treatment device; 11. return feeder; 12. steam valve; 13. steam pipe; 131. first steam pipe; 132. second steam pipe; 14. recirculating flue gas pipe; 15. primary air pipe; 16. hot flue gas pipe; 17. cold flue gas pipe; 171. first cold flue gas pipe; 172. second cold flue gas pipe; 18. flue gas fan; 19. forced air fan; 20. supplementary combustion fan; 21. induced draft fan; 22. carbon exhaust pipe; 23. cooler; 24. sorting bin; 25. supplementary combustion air pipe; 26. hot flue gas valve; 27. cold flue gas valve. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] Example 1

[0026] In a typical embodiment of the present invention, a circulating fluidized bed activation furnace system is provided, such as Figure 1 As shown, it includes an adiabatic circulating fluidized bed boiler 5, a cyclone separator 6, a flue gas afterburner 7 and a waste heat boiler 9; the feed port of the adiabatic circulating fluidized bed boiler 5 is connected to the return device 11 below the cyclone separator 6 through a feed leg 2, and a coal feeding device 1 is arranged on the feed leg 2; the flue gas outlet of the adiabatic circulating fluidized bed boiler 5 is connected to the cyclone separator 6, the flue gas afterburner 7 and the waste heat boiler 9 in sequence through a pipeline; a pyrolysis zone 3 and an activation zone 4 are arranged in the adiabatic circulating fluidized bed boiler 5; the bottom of the pyrolysis zone 3 is connected to the primary air duct 15, and the bottom of the activation zone 4 is connected to the steam pipeline, the recycled flue gas pipeline and the primary air duct.

[0027] The adiabatic circulating fluidized bed boiler 5 is provided with a pyrolysis zone and an activation zone, which are used to realize the pyrolysis process and the activation process of coal respectively. By arranging the primary air duct, steam duct and recirculating flue gas duct at the bottom of the activation zone, the flow ratio of each fluid is adjusted, and the oxygen content in the pyrolysis zone and the activation zone can be flexibly adjusted, thereby adjusting the temperature. In addition, by arranging the primary air duct, steam duct and recirculating flue gas duct at the bottom of the adiabatic circulating fluidized bed boiler, the fluid flow at each point is adjusted, and the pressure difference of the material layer at each point can be flexibly adjusted, thereby adjusting the particle residence time.

[0028] The cyclone separator 6 is used to achieve gas-solid separation of the hot flue gas generated by the adiabatic circulating fluidized bed boiler 5. The separated hot flue gas enters the flue gas afterburner 7, and the separated solid enters the return feeder 11 at the bottom of the cyclone separator 6. The solid in the return feeder 11 is again sent to the adiabatic circulating fluidized bed boiler 5 through the material leg 2.

[0029] The flue gas afterburner 7 is used for secondary complete combustion of combustible gases in the flue gas. A flue gas inlet, two flue gas outlets and a supplementary combustion air inlet are arranged on the flue gas afterburner 7. The flue gas inlet is connected to the flue gas outlet of the cyclone separator 6 through a pipeline, and the two flue gas outlets are respectively connected to the heat exchanger 8 and the waste heat boiler 9. The supplementary combustion air inlet is connected to the supplementary combustion fan 20 through the heat exchanger 8. In the flue gas afterburner 7, air is supplemented for secondary combustion to ensure complete combustion and obtain high-temperature flue gas.

[0030] The heat exchanger 8 is used to recover the heat in the hot flue gas. A hot flue gas duct 16, a supplementary combustion air duct 25 and a primary air duct 15 pass through the inside of the heat exchanger 8. The hot flue gas duct 16 serves as a hot fluid duct, and the supplementary combustion air duct 25 and the primary air duct 15 serve as cold fluid ducts. In the heat exchanger 8, the heat of the hot flue gas is exchanged with the supplementary combustion air duct 25 and the primary air duct 15 to preheat the supplementary combustion air and the primary air, thereby recovering and utilizing the heat of the hot flue gas.

[0031] Furthermore, the inlet of the hot flue gas duct 16 is connected to the flue gas outlet of the flue gas afterburning chamber 7, and the outlet of the hot flue gas duct 16 is connected to the recirculating flue gas duct 14 through the flue gas fan 18; the outlet of the supplementary combustion air duct 25 is connected to the flue gas afterburning chamber 7, and the inlet is connected to the supplementary combustion fan 20; the inlet of the primary air duct 15 is connected to the blower 19, and the outlet is connected to the pyrolysis zone 3 and the activation zone 4 through multiple pipes.

[0032] In this embodiment, the waste heat boiler 9 is connected to the flue gas afterburner 7 at the top, the cold flue gas pipeline 17 is connected to the bottom of the waste heat boiler 9, and the steam pipeline 13 is connected to the rear of the waste heat boiler 9.

[0033] Furthermore, the cold smoke duct 17 is connected to the first cold smoke duct 171 and the second cold smoke duct 172 respectively. The first cold smoke duct 171 is connected to the hot smoke duct 16. The first cold smoke duct 171 is provided with a cold smoke valve 27. The mixing ratio of cold and hot smoke is adjusted to ensure that the smoke temperature is controlled within the temperature tolerance range of the smoke fan (a high temperature fan with a temperature resistance of 600-800°C is selected).

[0034] The second cold flue gas duct 172 is connected to the flue gas treatment device 10 after passing through the induced draft fan 21, and the flue gas is discharged after being treated by the flue gas treatment device 10 to meet the standards.

[0035] Furthermore, the steam pipe 13 is connected to a first steam pipe 131 and a second steam pipe 132 respectively, a steam valve 12 is provided on the steam pipe 13, an outlet of the first steam pipe 131 is connected to a return device 11, and an outlet of the second steam pipe 132 is connected to the activation zone 4 inside the adiabatic circulating fluidized bed boiler 5.

[0036] In this embodiment, the bottom of the pyrolysis zone 3 is arranged in an inclined manner, which is conducive to the horizontal movement of unpyrolyzed (large specific gravity) and large particle size materials that are difficult to fluidize to the activation zone at a lower fluidization wind speed, effectively avoiding the occurrence of non-fluidized dead zones without increasing the fluidization air volume to cause a decrease in product yield; the activation zone 4 is arranged horizontally, and the horizontal movement of materials will not be too fast, ensuring sufficient activation time. The material leg is the channel for the fine particles separated by the separator to return to the furnace. This part of the particles has a higher temperature (700-800℃) and excellent fluidity. Coal is fed here, and the coal and fine particles are fully mixed and preliminarily heated.

[0037] In this embodiment, the outlet of the activation zone 4 is connected to a cooler 23 and a sorting bin 24 in sequence through a carbon discharge pipe 22 .

[0038] The working principle of the circulating fluidized bed activation furnace system provided in this embodiment is as follows:

[0039] The coal enters the feed leg through the coal feeding device and is preheated in the feed leg before entering the pyrolysis zone of the adiabatic circulating fluidized bed boiler. The preheating temperature in the feed leg is 650-700°C, and the temperature in the pyrolysis zone is 800-850°C. After pyrolysis, the coal is converted into semi-coke and continues to move downward to enter the activation zone for activation. The temperature in the activation zone is 900-950°C. After activation, the coal continues to move downward and is discharged through the carbon discharge pipe. It continues to move downward to enter the cooler 23 for cooling, and then enters the sorting bin 24 for sorting.

[0040] The flue gas generated in the adiabatic circulating fluidized bed boiler enters the cyclone separator for gas-solid separation, and the flue gas temperature is 800-900℃; the separated solids return to the adiabatic circulating fluidized bed boiler through the return feeder, and the separated flue gas enters the flue gas afterburner for reburning, and the temperature entering the flue gas afterburner is 800-850℃; the flue gas generated by reburning enters the waste heat boiler and the heat exchanger respectively, and the temperature of the flue gas coming out of the flue gas afterburner is 950-1000℃; steam is provided to the activation zone of the adiabatic circulating fluidized bed boiler through the waste heat boiler, and the steam temperature provided is 200-300℃; the hot flue gas after heat exchange in the heat exchanger is mixed with the cold flue gas generated by the waste heat boiler, and the temperature of the hot flue gas after heat exchange in the heat exchanger is 700-750℃, and the temperature of the cold flue gas generated by the waste heat boiler is 100-120℃; it is provided to the activation zone of the adiabatic circulating fluidized bed boiler as recycled flue gas, and the temperature of the recycled flue gas is 600-650℃.

[0041] Example 2

[0042] In a typical embodiment of the present invention, a working method of a circulating fluidized bed activation furnace system is provided, comprising the following steps:

[0043] The coal enters the feed leg through the coal feeding device and is preheated in the feed leg before entering the pyrolysis zone of the adiabatic circulating fluidized bed boiler. After pyrolysis, the coal is converted into semi-coke, and continues to move downward into the activation zone for activation. After activation, it continues to move downward and is discharged through the carbon discharge pipe.

[0044] The flue gas generated in the adiabatic circulating fluidized bed boiler enters the cyclone separator for gas-solid separation. The separated solids are returned to the adiabatic circulating fluidized bed boiler through the return feeder. The separated flue gas enters the flue gas afterburner for reburning. The flue gas generated by the reburning enters the waste heat boiler and the heat exchanger respectively. The waste heat boiler provides steam for the activation zone of the adiabatic circulating fluidized bed boiler. The hot flue gas after heat exchange in the heat exchanger and the cold flue gas generated by the waste heat boiler are mixed and provided to the activation zone of the adiabatic circulating fluidized bed boiler as recycled flue gas.

[0045] The flue gas generated in the adiabatic circulating fluidized bed boiler enters the cyclone separator for gas-solid separation. The separated solids return to the adiabatic circulating fluidized bed boiler through the return device. The separated flue gas enters the flue gas afterburner for reburning. The flue gas generated by the reburning enters the waste heat boiler and the heat exchanger respectively.

[0046] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A circulating fluidized bed activation furnace system, characterized in that: It includes an adiabatic circulating fluidized bed boiler, a cyclone separator, a flue gas afterburner and a waste heat boiler; the feed port of the adiabatic circulating fluidized bed boiler is connected to the return feeder below the cyclone separator through a feed leg, and a coal feeding device is arranged on the feed leg; the flue gas outlet of the adiabatic circulating fluidized bed boiler is connected to the cyclone separator, the flue gas afterburner and the waste heat boiler in sequence through a pipeline; a pyrolysis zone and an activation zone are arranged in the adiabatic circulating fluidized bed boiler; the bottom of the pyrolysis zone is connected to a primary air duct, and the bottom of the activation zone is connected to a steam pipeline, a recycled flue gas pipeline and a primary air duct.

2. The circulating fluidized bed activation furnace system according to claim 1, characterized in that: The flue gas afterburner is connected to the heat exchanger, and a hot flue gas duct, a supplementary combustion air duct and a primary air duct pass through the inside of the heat exchanger. The hot flue gas duct serves as a hot fluid duct, and the supplementary combustion air duct and the primary air duct serve as cold fluid ducts.

3. The circulating fluidized bed activation furnace system according to claim 2, characterized in that: The inlet of the hot flue gas duct is connected to the flue gas outlet of the flue gas afterburning chamber, and the outlet of the hot flue gas duct is connected to the recirculation flue gas duct through a flue gas fan; the outlet of the supplementary combustion air duct is connected to the flue gas afterburning chamber, and the inlet is connected to the supplementary combustion fan; the inlet of the primary air duct is connected to the blower, and the outlet is connected to the pyrolysis zone and the activation zone through multiple pipes.

4. The circulating fluidized bed activation furnace system according to claim 1, characterized in that: The waste heat boiler is connected to the flue gas afterburner at the top, the cold flue gas pipeline is connected to the bottom of the waste heat boiler, and the steam pipeline is connected to the rear of the waste heat boiler.

5. The circulating fluidized bed activation furnace system according to claim 4, characterized in that: The cold smoke duct is connected to the first cold smoke duct and the second cold smoke duct respectively. The first cold smoke duct is connected to the hot smoke duct, and the second cold smoke duct is connected to the smoke treatment device after passing through the induced draft fan.

6. The circulating fluidized bed activation furnace system according to claim 4, characterized in that: The steam pipe is connected to the first steam pipe and the second steam pipe respectively. A steam valve is arranged on the steam pipe. The outlet of the first steam pipe is connected to the return device, and the outlet of the second steam pipe is connected to the activation zone inside the adiabatic circulating fluidized bed boiler.

7. The circulating fluidized bed activation furnace system according to claim 1, characterized in that: The bottom of the pyrolysis zone is arranged in an inclined manner, and the activation zone is arranged in a horizontal manner.

8. The circulating fluidized bed activation furnace system according to claim 1, characterized in that: The outlet of the activation zone is connected to a cooler and a sorting bin in sequence through a carbon discharge pipe.

9. The circulating fluidized bed activation furnace system according to claim 1, characterized in that: The smoke inlet of the smoke afterburner is communicated with the smoke outlet of the cyclone separator.

10. A method for operating a circulating fluidized bed activation furnace system according to any one of claims 1 to 9, characterized in that: The following steps are involved: The coal enters the feed leg through the coal feeding device and is preheated in the feed leg before entering the pyrolysis zone of the adiabatic circulating fluidized bed boiler. After pyrolysis, the coal is converted into semi-coke, and continues to move downward into the activation zone for activation. After activation, it continues to move downward and is discharged through the carbon discharge pipe. The flue gas generated in the adiabatic circulating fluidized bed boiler enters the cyclone separator for gas-solid separation. The separated solids are returned to the adiabatic circulating fluidized bed boiler through the return feeder. The separated flue gas enters the flue gas afterburner for reburning. The flue gas generated by the reburning enters the waste heat boiler and the heat exchanger respectively. The waste heat boiler provides steam for the activation zone of the adiabatic circulating fluidized bed boiler. The hot flue gas after heat exchange in the heat exchanger and the cold flue gas generated by the waste heat boiler are mixed and provided to the activation zone of the adiabatic circulating fluidized bed boiler as recycled flue gas.

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