Deslagging device and method for coal water slurry gasification coarse slag with low carbon content

Abstract

The invention belongs to the technical field of coal water slurry gasification, and particularly relates to a deslagging device and method for coal water slurry gasification coarse slag with low carbon content. Fine slag generated by combustion of the coal water slurry gasification furnace is high in carbon content, and coarse slag is low in carbon content; fine slag is inevitably mixed into coarse slag generated in the prior art, so that the carbon content of the coarse slag is high; through the cyclone separator, slag water discharged by the lock hopper of the coal water slurry gasification device is subjected to cyclone separation to obtain fine slag, and then coarse slag is subjected to dehydration treatment to obtain coarse slag with low carbon content; the cyclone separator is arranged behind the lock hopper, the operation pressure and investment of the cyclone separator can be greatly reduced, meanwhile, clear black water generated by a coarse slag pool and a settling tank in the coal water slurry gasification device or ammonia-containing wastewater generated by the coal water slurry gasification device is used for the cyclone separator, and compared with a coarse slag slurrying and carbon separation technology in the prior art, the cyclone separator has the advantages that the operation is simple, and the cost is low. The consumption of fresh water is greatly reduced, and the output of wastewater and the load of a wastewater treatment device are also reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of water-coal slurry gasification, in particular to a slag discharge device and method for water-coal slurry gasification coarse slag with low carbon content. Background Art

[0002] As one of the core technologies of the coal chemical industry, water-coal slurry gasification technology converts organic matter in coal into combustible gas through high temperature, high pressure and catalysts, and has significant advantages such as high efficiency, environmental protection and energy saving. At present, this technology has become an indispensable clean energy technology in the power, chemical, metallurgical and other industries.

[0003] However, a large amount of coarse slag will be produced during the gasification process of water-coal slurry. The physical properties of these coarse slags vary greatly due to factors such as the type of raw coal, gasification conditions and operating process, and their chemical composition is complex. Their chemical composition mainly includes inorganic minerals such as oxides such as SiO2, Al2O3, CaO and Fe2O3, and a small amount of unburned carbonaceous residues. In addition, the coarse slag also contains a certain amount of moisture and volatiles, with a particle size ranging from several millimeters to tens of millimeters, presenting blocky and granular forms, complex pore structure, and large specific surface area. These factors have a huge impact on the utilization and treatment of coarse slag.

[0004] At present, the main treatment methods of coal chemical enterprises for crude slag from water-coal slurry gasification include self-transportation or entrusting a third party to transport and stack it. This treatment method not only occupies a large amount of land resources, but also, due to the high water content of the crude slag, it is prone to leakage and dust during transportation and storage, causing certain pollution to the environment. In addition, the unburned carbon resources in the crude slag are not fully utilized, resulting in a waste of carbon resources. Therefore, it is of great significance to strengthen the research on the treatment and disposal technology of crude slag and realize its resource utilization and harmless treatment.

[0005] In order to make efficient and comprehensive utilization of crude slag, many enterprises or scientific research institutions have actively developed efficient separation and extraction technologies to achieve efficient separation of inorganic minerals and unburned carbon residues in crude slag; however, they have not explored how to reduce the carbon content of crude slag before it is formed, but have studied the separation of residual carbon and inorganic minerals after the crude slag is formed. This separation technology also requires pulping of crude slag, which requires a large amount of water resources, and the wastewater formed increases the load of the sewage treatment device. Therefore, it is particularly necessary to study the direct production of low-carbon slag by water-coal slurry gasification. Summary of the invention

[0006] Based on the problems of the prior art, the present invention provides a slag discharge device and method with low carbon content in coarse slag from water-coal slurry gasification. The present invention enables the coarse slag discharged from the gasification device to have low carbon content, broadens the resource utilization approach of the coarse slag, and also reduces the consumption of water resources for carbon content in the coarse slag, reduces the amount of wastewater, and reduces the load on the wastewater treatment device.

[0007] In order to solve the above technical problems, the technical solution of the present invention is as follows: A slag discharge device for coarse slag with low carbon content from water-coal slurry gasification, comprising a gasifier, a lock bucket, a slag water buffer tank, and a cyclone separator, wherein the bottom of the gasifier is connected to the top of the lock bucket through a slag breaker, the bottom of the lock bucket is connected to the top of the slag water buffer tank through a pipeline, the bottom of the slag water buffer tank is connected to the cyclone separator through a pipeline, the coarse slag outlet at the bottom of the cyclone separator is connected to the coarse slag pool through a pipeline, the water inlet of the cyclone separator is connected to the buffer water tank, and the water outlet of the cyclone separator is connected to the sedimentation tank through a pipeline; the clear liquid outlet of the coarse slag pool and the clear liquid outlet of the sedimentation tank are connected to the buffer water tank through a pipeline and a clear liquid water pump respectively; Furthermore, a plurality of cyclone separators are arranged in parallel or in series.

[0008] Furthermore, the lock bucket is provided with a pressure equalizing pipe connected to the quenching chamber of the gasifier; the lock bucket is also provided with a water replenishment buffer tank, and a pressure relief pipe is provided on the top of the lock bucket to connect to the top of the water replenishment buffer tank; Furthermore, the lock bucket is provided with a slag discharge circulation pump, the inlet of the slag discharge circulation pump is connected to the lock bucket, and the outlet of the slag discharge circulation pump is connected to the quenching chamber of the gasifier; Furthermore, the water inlet of the cyclone separator is lower than the water outlet of the cyclone separator; Furthermore, the buffer water tank is also connected to the fresh water network and / or the ammonia-containing wastewater pipeline of the coal gasification device through a pipeline; A method for removing slag from water-coal slurry gasification slag with low carbon content, comprising the following steps: (1) The coal-water slurry is burned in the gasifier to produce gasification slag and synthesis gas, which enter the quenching water at the bottom of the gasifier for cooling. The cooled synthesis gas carries a part of the fine slag and flows out from the outlet on the side of the gasifier. The cooled coarse slag and the other part of the fine slag are crushed by the slag crusher at the bottom of the gasifier to obtain coarse slag containing fine slag; (2) The coarse slag obtained in step (1) is discharged into the lock bucket. When a certain amount of coarse slag is discharged into the lock bucket, the gasifier stops discharging slag and the lock bucket starts discharging slag into the slag water buffer tank. After the lock bucket finishes discharging slag, the gasifier starts discharging slag into the lock bucket; (3) In step (2), the coarse slag and water in the slag water buffer tank enter the cyclone separator, and water is added to the cyclone separator at the same time. Under the action of the cyclone, the fine slag in the coarse slag is gradually separated from the coarse slag, and the coarse slag settles at the bottom of the cyclone separator and is discharged into the coarse slag pool. The separated fine slag is carried out of the cyclone separator by water and enters the sedimentation tank; the coarse slag at the bottom of the coarse slag pool is dehydrated to obtain coarse slag with low carbon content, and the fine slag slurry at the bottom of the sedimentation tank is dehydrated to obtain fine slag; the clarified black water from the sedimentation tank and the coarse slag pool is sent to the cyclone separator for continuous circulation to separate the fine slag by cyclone; Furthermore, when the lock bucket is in operation, the lock bucket is kept full of water through the water replenishment buffer tank; before the gasifier discharges slag, the lock bucket and the gasifier quenching chamber are pressure-equalized through a pressure equalizing pipeline; after the pressure equalization is completed, the gasifier starts to discharge slag, and the water in the lock bucket is circulated to the gasifier quenching chamber through a slag discharge circulation pump, and the slag in the quenching chamber is brought into the lock bucket.

[0009] Furthermore, the cyclone separator is replenished with clarified black water and / or fresh water from a sedimentation tank and / or clarified black water and / or ammonia-containing wastewater from a coarse slag pool.

[0010] Furthermore, the pressure difference between the lock bucket and the gasifier quenching chamber after equalization shall not be greater than 0.3MPa; the lock bucket is depressurized through a pressure relief pipe before slag discharge, and the pressure in the lock bucket after depressurization shall not be greater than 0.5MPa; Beneficial Effects

[0011] 1. Since the fine slag produced by the combustion of the water-coal slurry gasifier has a high carbon content and the coarse slag has a low carbon content, the present invention provides a cyclone separator to perform cyclone separation on the slag-water mixture discharged from the lock bucket of the water-coal slurry gasifier, and at the same time, water is added to the cyclone separator to perform cyclone separation on the fine slag in the coarse slag, and the water carries the fine slag out of the cyclone separator and enters the sedimentation tank, and the fine slag and water are sedimented and separated in the sedimentation tank, and the coarse slag at the bottom of the cyclone separator is discharged into the coarse slag pool and then dehydrated to obtain the coarse slag with low carbon content.

[0012] 2. The slag-water mixture discharged from the lock bucket of the present invention is separated into fine slag in the cyclone separator to obtain coarse slag with low carbon content, thereby avoiding the consumption of water resources in the coarse slag slurry carbon separation in the prior art, and also reducing the amount of wastewater generated by the coarse slag carbon separation, reducing the load of the wastewater treatment device.

[0013] 3. The present invention arranges the cyclone separator after the lock bucket, which can reduce the operating pressure of the cyclone separator, reduce the requirements for equipment, and reduce equipment investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of the present invention; In the figure: 1-gasification furnace; 2-lock hopper; 3-slag water buffer tank; 4-cyclone separator; 5-sedimentation tank; 6-buffer water tank; 7-coarse slag pool; 8-water replenishment buffer tank. DETAILED DESCRIPTION Example 1

[0015] Reference Figure 1Since the fine slag produced by the combustion of the water-coal slurry gasification furnace has a high carbon content and the coarse slag has a low carbon content; the coarse slag produced by the prior art inevitably contains fine slag, resulting in a high carbon content in the coarse slag, making it difficult to recycle the coarse slag; in addition, the prior art coarse slag pulping and carbon separation consumes a lot of water resources, generates a lot of wastewater, and puts a heavy load on the wastewater treatment device. In order to make the carbon content of the crude slag produced by the existing water-coal slurry gasification technology as low as possible, broaden the resource utilization channels of the crude slag, and at the same time reduce the consumption of water resources, reduce the amount of wastewater, and reduce the load of the wastewater treatment device, the present invention provides a slag discharge device with low carbon content of crude slag from water-coal slurry gasification, including a gasifier 1, a lock bucket 2, a slag water buffer tank 3, and a cyclone separator 4. The bottom of the gasifier 1 is connected to the top of the lock bucket 2 through a slag breaker, and the lock bucket 2 is provided with a pressure equalizing pipeline to be connected to the quenching chamber of the gasifier 1. Before the gasifier 1 discharges slag, the pressure is equalized through the pressure equalizing pipeline to reduce the pressure difference between the quenching chamber of the gasifier 1 and the lock bucket 2, so as to avoid the operation fluctuation of the gasifier 1 caused by excessive pressure difference during slag discharge; the bottom of the lock bucket 2 is connected to the top of the slag water buffer tank 3 through a pipeline, and the lock bucket 2 is also provided with a water replenishment buffer tank 8 to provide sufficient water for the lock bucket 2 to operate, and a pressure relief pipeline is provided on the top of the lock bucket 2 to be connected to the top of the water replenishment buffer tank 8. Before the lock bucket 2 discharges slag, the pressure in the lock bucket 2 is reduced to 0.5MP through the pressure relief pipeline. a, to avoid excessive pressure in the lock bucket 2 causing impact on the slag water buffer tank 3 during slag discharge; the lock bucket 2 is provided with a slag discharge circulation pump, the inlet of the slag discharge circulation pump is connected to the lock bucket 2, and the outlet of the slag discharge circulation pump is connected to the quenching chamber of the gasifier 1; so that the water in the lock bucket 2 is forced to circulate into the quenching chamber of the gasifier 1, and at the same time, the slag water in the quenching chamber of the gasifier 1 enters the lock bucket 2; the bottom of the slag water buffer tank 3 is connected to the cyclone separator 4 through a pipeline, and the cyclone separator 4 is provided with one; the cyclone separator The bottom coarse slag outlet of 4 is connected with the coarse slag pool 7 through a pipeline, the water inlet of the cyclone separator 4 is connected with the buffer water tank 6, and the water outlet of the cyclone separator 4 is connected with the sedimentation tank 5 through a pipeline; the water inlet of the cyclone separator 4 is lower than the water outlet of the cyclone separator 4; the buffer water tank 6 is also connected with the fresh water network and the ammonia-containing wastewater pipeline of the coal gasification device through a pipeline; the clear liquid outlet of the coarse slag pool 7 and the clear liquid outlet of the sedimentation tank 5 are connected to the buffer water tank 6 through a pipeline and a clear liquid water pump respectively.

[0016] A method for removing slag from water-coal slurry gasification slag with low carbon content, comprising the following steps: (1) The coal-water slurry is burned in the gasifier 1 to produce gasified slag and synthesis gas, which enter the quenching water at the bottom of the gasifier 1 for cooling. The cooled synthesis gas carries a part of the fine slag and flows out from the outlet on the side of the gasifier 1. The cooled coarse slag and the other part of the fine slag are crushed by the slag crusher at the bottom of the gasifier 1 to obtain coarse slag containing fine slag; (2) The coarse slag obtained in step (1) is discharged into the lock hopper 2. When a certain amount of coarse slag is discharged into the lock hopper 2, the gasifier 1 stops discharging slag, and the lock hopper 2 starts discharging slag into the slag water buffer tank 3. After the lock hopper 2 finishes discharging slag, the gasifier 1 starts discharging slag into the lock hopper 2. (3) In step (2), the coarse slag and water in the slag water buffer tank 3 enter the cyclone separator 4, and water is added to the cyclone separator 4. Under the action of the cyclone, the fine slag in the coarse slag is gradually separated from the coarse slag, and the coarse slag is settled at the bottom of the cyclone separator 4 and discharged into the coarse slag pool 7. The separated fine slag is carried out of the cyclone separator 4 by water and enters the sedimentation tank 5; the coarse slag at the bottom of the coarse slag pool 7 is dehydrated to obtain coarse slag with low carbon content, and the fine slag slurry at the bottom of the sedimentation tank 5 is dehydrated to obtain fine slag; the clarified black water from the sedimentation tank 5 and the coarse slag pool 7 is sent to the cyclone separator 4 to continue to circulate and cyclone to separate the fine slag; When the lock hopper 2 is in operation, the lock hopper 2 is kept full of water through the water replenishment buffer tank 8; before the gasifier 1 discharges slag, the lock hopper 2 and the quenching chamber of the gasifier 1 are pressure-equalized through a pressure-equalizing pipeline; after the pressure equalization is completed, the gasifier 1 starts to discharge slag, and the water in the lock hopper 2 is circulated to the quenching chamber of the gasifier 1 through a slag discharge circulation pump, and the slag in the quenching chamber is brought into the lock hopper 2.

[0017] The cyclone separator 4 is replenished with clarified black water from the sedimentation tank 5 and clarified black water from the coarse slag pool 7 .

[0018] The pressure difference between the lock hopper 2 and the quenching chamber of the gasifier 1 after equalization shall not be greater than 0.3MPa; the lock hopper 2 is depressurized through a pressure relief pipe before slag discharge, and the pressure in the lock hopper 2 after depressurization shall not be greater than 0.5MPa; Another embodiment is different from the embodiment 1 in that: two cyclone separators 4 are provided, and the two cyclone separators 4 are connected in parallel; Another embodiment is different from the embodiment 1 in that: two cyclone separators 4 are provided, and three cyclone separators 4 are connected in parallel; Another embodiment is different from the embodiment 1 in that: two cyclone separators 4 are provided, and the two cyclone separators 4 are connected in series; Another embodiment is different from the embodiment 1 in that: three cyclone separators 4 are provided, and the three cyclone separators 4 are connected in series; Another embodiment is different from the embodiment 1 in that the cyclone separator 4 is replenished with clarified black water from the sedimentation tank 5, clarified black water from the coarse slag pool 7, and ammonia-containing wastewater produced by the gasification device.

[0019] Another embodiment is different from the embodiment 1 in that the cyclone separator 4 is replenished with clarified black water and fresh water from the sedimentation tank 5 , clarified black water from the coarse slag pool 7 , and ammonia-containing wastewater generated by the gasification device.

[0020] The working principle of the present invention is as follows: since the fine slag produced by the combustion of the water-coal slurry gasification furnace 1 has a high carbon content and the coarse slag has a low carbon content; and the coarse slag produced by the prior art is inevitably mixed with fine slag, resulting in a high carbon content in the coarse slag; the present invention utilizes a cyclone separator 4 to cyclone the slag-water mixture discharged from the lock bucket 2 of the water-coal slurry gasification device to separate the fine slag, and then dehydrates the coarse slag to obtain coarse slag with a low carbon content; in addition, the present invention arranges the cyclone separator 4 behind the lock bucket 2 of the water-coal slurry gasification device, which can greatly reduce the operating pressure and investment of the cyclone separator 4, and at the same time, the clarified black water produced by the coarse slag pool 7 and the sedimentation tank 5 in the water-coal slurry gasification device or the ammonia-containing wastewater produced by the water-coal slurry gasification device is used for the cyclone separator 4, which greatly reduces the consumption of fresh water, the amount of wastewater generated and the load of the wastewater treatment device compared with the coarse slag slurry carbon separation technology in the prior art.

[0021] Modifications and changes to the present invention made by the inventors familiar with the present invention are all within the patent scope of the present invention and are not limited to the embodiments.

Claims

1. A slag discharge device with low carbon content of crude slag from water-coal slurry gasification, characterized by: It includes a gasifier, a lock bucket, a slag water buffer tank, and a cyclone separator. The bottom of the gasifier is connected to the top of the lock bucket through a slag breaker, the bottom of the lock bucket is connected to the top of the slag water buffer tank through a pipeline, the bottom of the slag water buffer tank is connected to the cyclone separator through a pipeline, the bottom coarse slag outlet of the cyclone separator is connected to the coarse slag pool through a pipeline, the water inlet of the cyclone separator is connected to the buffer water tank, and the water outlet of the cyclone separator is connected to the sedimentation tank through a pipeline; the clear liquid outlet of the coarse slag pool and the clear liquid outlet of the sedimentation tank are connected to the buffer water tank through a pipeline and a clear liquid water pump respectively.

2. The slag discharge device for low carbon content coarse slag from water-coal slurry gasification according to claim 1, characterized in that: The cyclone separators are arranged in multiple units in parallel or in series.

3. The slag discharge device for low carbon content coarse slag from water-coal slurry gasification according to claim 1, characterized in that: The lock bucket is provided with a pressure equalizing pipe connected to the quenching chamber of the gasifier; the lock bucket is also provided with a water replenishment buffer tank, and a pressure relief pipe is provided on the top of the lock bucket to connect to the top of the water replenishment buffer tank.

4. The slag discharge device for low carbon content coarse slag from water-coal slurry gasification according to claim 1, characterized in that: The lock bucket is provided with a slag discharge circulation pump, the inlet of the slag discharge circulation pump is connected to the lock bucket, and the outlet of the slag discharge circulation pump is connected to the quenching chamber of the gasifier.

5. The slag discharge device for low carbon content coarse slag from water-coal slurry gasification according to claim 1, characterized in that: The water inlet of the cyclone separator is lower than the water outlet of the cyclone separator.

6. The slag discharge device for low carbon content coarse slag from water-coal slurry gasification according to claim 1, characterized in that: The buffer water tank is also connected to the fresh water network and / or the ammonia-containing wastewater pipeline of the coal gasification device through a pipeline.

7. A method for removing slag from water-coal slurry gasification slag with low carbon content, which is realized by the slag removal device according to any one of claims 1 to 6, comprising the following steps: (1) The coal-water slurry is burned in the gasifier to produce gasification slag and synthesis gas, which enter the quenching water at the bottom of the gasifier for cooling. The cooled synthesis gas carries a part of the fine slag and flows out from the outlet on the side of the gasifier. The cooled coarse slag and the other part of the fine slag are crushed by the slag crusher at the bottom of the gasifier to obtain coarse slag containing fine slag; (2) The coarse slag obtained in step (1) is discharged into the lock bucket. When a certain amount of coarse slag is discharged into the lock bucket, the gasifier stops discharging slag and the lock bucket starts discharging slag into the slag water buffer tank. After the lock bucket finishes discharging slag, the gasifier starts discharging slag into the lock bucket; (3) In step (2), the coarse slag and water in the slag water buffer tank enter the cyclone separator, and water is added to the cyclone separator at the same time. Under the action of the cyclone, the fine slag in the coarse slag is gradually separated from the coarse slag, and the coarse slag is settled at the bottom of the cyclone separator and discharged into the coarse slag pool. The separated fine slag is carried out of the cyclone separator by water and enters the sedimentation tank; the coarse slag at the bottom of the coarse slag pool is dehydrated to obtain coarse slag with low carbon content, and the fine slag slurry at the bottom of the sedimentation tank is dehydrated to obtain fine slag; the clarified black water from the sedimentation tank and the coarse slag pool is sent to the cyclone separator to continue to circulate and cyclone to separate the fine slag.

8. The method for removing slag from water-coal slurry gasification slag with low carbon content according to claim 7, characterized in that: When the lock bucket is in operation, the lock bucket is kept full of water through the water replenishment buffer tank; before the gasifier discharges slag, the lock bucket and the quenching chamber of the gasifier are pressure-equalized through a pressure-equalizing pipeline; after the pressure equalization is completed, the gasifier starts to discharge slag, and the water in the lock bucket is circulated to the quenching chamber of the gasifier through a slag discharge circulation pump, and the slag in the quenching chamber is brought into the lock bucket.

9. The method for removing slag from water-coal slurry gasification slag with low carbon content according to claim 7, characterized in that: The cyclone separator is replenished with clarified black water and / or fresh water from a sedimentation tank and / or clarified black water and / or ammonia-containing wastewater from a coarse slag pool.

10. The method for removing slag from water-coal slurry gasification slag with low carbon content according to claim 7, characterized in that: The pressure difference between the lock bucket and the gasification furnace quenching chamber after equalization shall not be greater than 0.3MPa; the lock bucket shall be pressure-relieved through a pressure relief pipe before slag discharge, and the pressure in the lock bucket shall not be greater than 0.5MPa after pressure relief.

Images