CN109777521B - Coal gasification system and gasification process - Google Patents
Coal gasification system and gasification process Download PDFInfo
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- CN109777521B CN109777521B CN201910216416.XA CN201910216416A CN109777521B CN 109777521 B CN109777521 B CN 109777521B CN 201910216416 A CN201910216416 A CN 201910216416A CN 109777521 B CN109777521 B CN 109777521B
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- 238000002309 gasification Methods 0.000 title claims abstract description 167
- 239000003245 coal Substances 0.000 title claims abstract description 89
- 238000000034 method Methods 0.000 title claims abstract description 38
- 230000008569 process Effects 0.000 title claims abstract description 34
- 239000010881 fly ash Substances 0.000 claims abstract description 186
- 239000000428 dust Substances 0.000 claims abstract description 84
- 238000006243 chemical reaction Methods 0.000 claims abstract description 59
- 239000003034 coal gas Substances 0.000 claims abstract description 43
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 34
- 239000000463 material Substances 0.000 claims abstract description 20
- 239000002817 coal dust Substances 0.000 claims abstract description 14
- 239000000843 powder Substances 0.000 claims abstract description 13
- 239000012429 reaction media Substances 0.000 claims abstract description 10
- 239000002245 particle Substances 0.000 claims description 88
- 239000007789 gas Substances 0.000 claims description 45
- 239000002918 waste heat Substances 0.000 claims description 18
- 239000000498 cooling water Substances 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 4
- 238000003860 storage Methods 0.000 claims description 4
- 238000004939 coking Methods 0.000 abstract description 7
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 230000000694 effects Effects 0.000 description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 15
- 239000001301 oxygen Substances 0.000 description 15
- 229910052760 oxygen Inorganic materials 0.000 description 15
- 229910052799 carbon Inorganic materials 0.000 description 14
- 239000002893 slag Substances 0.000 description 8
- 238000001816 cooling Methods 0.000 description 7
- 238000010517 secondary reaction Methods 0.000 description 7
- 238000005457 optimization Methods 0.000 description 4
- 230000003749 cleanliness Effects 0.000 description 3
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- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
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- 238000005054 agglomeration Methods 0.000 description 1
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Abstract
The invention discloses a coal gasification system and a gasification process, and belongs to the field of coal gas manufacturing. The system comprises a gasification furnace, a dust removing device and a fly ash burner, wherein the air inlet end of the dust removing device is communicated with the gas outlet of the gasification furnace, and the fly ash burner comprises a gasifying agent channel, a steam channel and a coal dust channel; the inlet end of the gasifying agent channel is connected with an air source, the inlet end of the steam channel is connected with a steam device, and the inlet end of the coal dust channel is connected with a discharge port of the dust removing device; the outlet ends of the gasifying agent channel, the steam channel and the coal powder channel are communicated with a premixing zone of the fly ash burner, and the premixing zone is connected with a material returning port of the gasifying furnace. The process adopts the coal gasification system to produce gas, can collect the fly ash in the coal gasification reaction, and is fully mixed with the reaction medium before returning to the gasification furnace, thereby greatly improving the reaction efficiency of the fly ash after returning to the gasification furnace and avoiding coking.
Description
Technical Field
The invention belongs to the field of coal gas manufacturing, and particularly relates to a coal gasification system and a gasification process.
Background
The country is rich in coal, lack of oil and less in gas, and the energy structure background determines that coal is still the main body of energy in China in a quite long time in the future, and is an important support for economic development in China. Among the various utilization modes of coal, the gasification process of coal is a process of converting solid raw material coal which is difficult to process and remove useless components into gas which is easy to purify and apply. Up to now, various reactors have been developed, including fixed bed, fluidized bed and entrained flow reactors, to achieve the objectives of producing fuel gas, synthesis gas, etc. by gasification of coal. Among these reactors, fluidized bed coal gasification reactors have found wide application in the coal gasification field due to their very high heat and mass transfer efficiency and ability to process large amounts of raw coal particles.
In a fluidized bed coal gasification reactor, the effective utilization of fly ash exiting a gasifier is one of the key problems of ensuring stable gas production and improving carbon conversion rate of the gasifier. For a long time, it is generally easy to think that the fly ash is captured by a high-temperature cyclone separator and returned into the gasification furnace so as to reduce the content of residual carbon in the fly ash and achieve the purposes of improving the carbon conversion rate and the gas yield. However, the conventional fluidized bed coal gasification reactor has high fly ash volatile matter and is difficult to catch fire, and the temperature in the fluidized bed reactor is low (about 1000 ℃), so that the fly ash reaction is difficult, and coking phenomenon occurs in the reactor.
The Chinese patent application number is: cn20181082878. X, publication date is: patent literature of 2018, 11 and 6 discloses a fluidized bed pulverized coal gasification device with zero fly ash emission and a process, wherein the device comprises a gasification system composed of a gasification furnace, a high-temperature cyclone separator, a waste heat boiler, a high-efficiency cyclone separator, a dust remover and other structures, and a return system composed of a rotary material leg, a rotary material returning device, a two rotary material legs, a two rotary material returning device, a high-efficiency cyclone material returning device, a dust remover material leg, a dust remover material returning device, a primary ejector, a secondary ejector, a tertiary ejector, a return pipe and other structures. The gasification system and the material returning system in the device are matched for use, so that coarse fly ash and fine fly ash trapped by the gas-solid separator under high pressure can be directly returned to the high-temperature central jet flow area of the gasification furnace, the original temperature and pressure in the gasification furnace are maintained unchanged, zero discharge of the fly ash is realized, the effect of ash agglomeration in the furnace is improved to the maximum extent, meanwhile, the production environment is optimized, and the gasification process is a gasification process which has high gasification efficiency, can stably run for a long time and is environment-friendly. However, the device needs to send the fly ash below the distribution plate of the fluidized bed gasifier first, and then the fly ash enters the central jet flow area for reaction, and because the fly ash is gasified in the mode, when the fly ash generation amount is large, the fly ash is easily accumulated below the distribution plate of the gasifier and in the central jet flow area, and cokes at high temperature in the gasifier to cause blockage, so that the reaction efficiency of the fly ash is poor, even the gasification reaction of coal is influenced when serious, and equipment is damaged.
The Chinese patent application number is: CN201810958836.0, publication date: patent literature of 2018, 11 and 6 discloses a coupled coal gasification system and a method, and belongs to the technical field of clean and efficient utilization of coal. The system comprises a gasification system, a waste heat recovery system, a dust removal system and a fly ash circulating system which are sequentially connected, wherein the entrained-flow bed gasification furnace is connected to the downstream of the fluidized-bed gasification furnace, the waste heat recovery system adopts a multi-loop waste heat recovery mode, the heat of the system is fully utilized, and the heat efficiency is improved; the gasification system also comprises a cyclone mixer, the upper end of the entrained flow gasifier is provided with a gasification burner, the fly ash circulating system is connected with the gasification burner, and the feeding modes of coal dust, fly ash and gasifying agent are changed, so that the gasification reaction is more thorough, and the carbon conversion rate is obviously improved. According to the coupled coal gasification method, the gasification working section and the heat exchange working section are optimized based on the gasification system, so that the thermal efficiency of the gasification system is obviously improved, and the carbon conversion rate of coal is further improved. However, although this system allows fly ash and gasifying agent to enter the gasifier together for reaction, the mixing effect of the fly ash and gasifying agent is not very good, and therefore the fly ash enters the entrained-flow gasifier with a relatively high temperature for reaction, which is not suitable for use in a separate fluidized-bed gasifier. In addition, the gasification burner used in the system is not specially improved for the mixture of the fly ash and the gasifying agent, and mainly the fluidized bed and the gasification bed are combined to improve the conversion rate of carbon, so that the practical use effect is poor, and the fly ash cannot completely react.
In summary, the fly ash is fully mixed with various reaction media before being returned to the gasification furnace, so that the carbon conversion rate in the coal gasification process can be effectively improved, and no perfect measure for solving the problem exists at present.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems that the carbon conversion rate is low, the fly ash is difficult to treat and the reaction is difficult in the existing coal gasification process, the invention provides the coal gasification system which can collect the fly ash in the coal gasification reaction and fully mix the fly ash with a reaction medium before returning to a gasification furnace, thereby greatly improving the reaction efficiency of the fly ash after returning to the gasification furnace and avoiding coking.
The invention also provides a coal gasification process, wherein the coal gasification system is adopted to produce gas, so that fly ash in the produced gas can be separated, collected and subjected to secondary reaction, the reaction efficiency of the fly ash is high, and the gas yield and the carbon conversion rate are effectively improved.
2. Technical proposal
In order to solve the problems, the invention adopts the following technical scheme.
The coal gasification system comprises a gasification furnace, a dust removing device and a fly ash burner, wherein the air inlet end of the dust removing device is communicated with the coal gas outlet of the gasification furnace, and the fly ash burner comprises a gasifying agent channel, a steam channel and a coal dust channel; the inlet end of the gasifying agent channel is connected with an air source, the inlet end of the steam channel is connected with a steam device, and the inlet end of the coal dust channel is connected with a discharge port of the dust removing device; the outlet ends of the gasifying agent channel, the steam channel and the coal powder channel are communicated with a premixing zone of the fly ash burner, and the premixing zone is connected with a material returning port of the gasifying furnace.
As the optimization of the technical scheme, the pulverized coal channel, the steam channel and the gasifying agent channel are of sleeve structures, and the pulverized coal channel, the steam channel and the gasifying agent channel are sequentially arranged from inside to outside; the outlet end of the gasifying agent channel and the outlet end of the steam channel are of a necking structure.
As the optimization of the technical scheme, the outer side of the gasifying agent channel in the fly ash burner is also provided with a cooling water channel, and the cooling water channel is not communicated with the premixing zone.
As the optimization of the technical scheme, the heat exchange device is also included; the heat exchange device comprises a preheater and a waste heat recoverer; the inlet end of the preheater is communicated with the gas outlet of the gasifier, and the outlet end of the preheater is communicated with the inlet end of the waste heat recoverer; the outlet end of the waste heat recoverer is communicated with the inlet end of the dust removing device.
Preferably, the dust removing device is a bag type dust remover.
Preferably, the cyclone separator is also included; the gas inlet end of the cyclone separator is communicated with the gas outlet of the gasifier, the gas outlet end of the cyclone separator is communicated with the inlet end of the heat exchange device, and the discharge port of the cyclone separator is communicated with the material returning port of the gasifier.
As the optimization of the technical scheme, the device also comprises a pneumatic conveying device; the inlet end of the pneumatic conveying device is connected with a discharge port of the dust removing device, and the outlet end of the pneumatic conveying device is connected with the inlet end of the coal dust channel; the pneumatic conveying device comprises a powder bin, a feeding tank and a feeder which are connected in sequence; an intermediate tank is also arranged between the powder bin and the feeding tank; the inlet end of the intermediate tank is communicated with the discharge port of the powder bin, and the outlet end of the intermediate tank is connected with the inlet end of the feed tank.
Preferably, the pneumatic conveying device conveys the fly ash to the fly ash burner through inert gas.
A coal gasification process comprising the steps of:
gasification section: conveying the coal material to a gasification furnace for gasification reaction, and discharging generated coal gas from a coal gas outlet of the gasification furnace;
heat exchange section: the gas generated by the gasification working section sequentially enters a preheater and a waste heat recoverer for heat exchange, and then enters a dust removal working section;
dust removal section: the gas subjected to heat exchange enters a dust removing device, and the gas subjected to dust removal is conveyed to downstream gas storage equipment;
and (3) a fly ash re-furnace working section: the fly ash separated by the dust removing section is conveyed to a fly ash burner, and the fly ash is mixed with a reaction medium in the fly ash burner and then enters a gasification furnace for reaction.
As a preferred technical scheme, the method also comprises a fly ash pretreatment section: the gas generated by the gasification working section is discharged from a gas outlet of the gasification furnace and then enters a cyclone separator, the cyclone separator separates fly ash particles with the particle size of more than 100 microns and directly conveys the fly ash particles to the gasification furnace for reaction, and the separated gas enters a heat exchange working section.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the coal gasification system, fly ash particles in coal gas are removed and collected through the dust removal device, so that on one hand, the cleanliness of the coal gas is improved, the coal gas is convenient to use, on the other hand, the collected fly ash particles contain residual carbon which is not completely reacted and can be returned to the gasification furnace for secondary reaction, and the carbon conversion rate and the coal gas yield of the coal gasification system are improved;
(2) According to the coal gasification system, the fly ash burner is arranged to be of a sleeve structure taking the coal dust channel as the center, and the outlet end of the gasifying agent channel and the outlet end of the steam channel are arranged to be of a necking structure, so that the mixing degree between the fly ash and the gasifying agent and the steam is enhanced, the reaction of the fly ash after returning to the gasification furnace is more complete, and the reaction efficiency is higher;
(3) According to the coal gasification system, the cooling water channel which is not communicated with the premixing zone is arranged on the outer side of the gasifying agent channel, so that the fly ash burner is cooled, and the damage of the fly ash burner due to high temperature is prevented;
(4) According to the coal gasification system, the heat exchange device is arranged between the dust removal device and the gasification furnace, high-temperature coal gas generated by the gasification furnace enters the dust removal device after being cooled by the heat exchange device, so that the damage of the dust removal device caused by the high-temperature coal gas can be prevented, the dust removal device is more diversified in use, and further, the preheater and the waste heat recoverer are adopted to progressively cool the discharged coal gas, and meanwhile, the heat in the hot coal gas is effectively recovered, so that the heat efficiency is remarkably improved;
(5) According to the coal gasification system, on the basis of cooling coal gas by the heat exchange device, the bag type dust collector is adopted to carry out dust removal treatment on the coal gas, fine fly ash in the coal gas can be separated and collected, the dust removal effect is good, and the obtained coal gas is high in cleanliness;
(6) According to the coal gasification system, the cyclone separator arranged between the heat exchange device and the gasification furnace can separate the fly ash particles with the particle size of more than 100 microns and return the fly ash particles to the gasification furnace for secondary reaction, the part of the fly ash particles with larger particle size contain more residual carbon, a better reaction effect can be obtained after the fly ash particles directly return to the gasification furnace, the reaction efficiency of the fly ash particles after returning to the gasification furnace is improved due to the high temperature of the fly ash particles, in addition, the working pressure of a subsequent dust removing device is effectively reduced, the working effect of the dust removing device is better, and the fly ash particles with smaller particle size collected by the dust removing device are more fully mixed with a reaction medium in the fly ash burner;
(7) According to the coal gasification system, fly ash particles collected by a dust removing device are conveyed to a fly ash burner by adopting a powder bin, a middle tank, a feed tank and a feeder which are sequentially connected, the pressure intensity of equipment is stable, the fly ash can be prevented from being blocked in the conveying process, the conveying speed of the fly ash can be quantitatively controlled, the fly ash is ensured to be fully mixed with a reaction medium in the fly ash burner, so that the fly ash is fully reacted after being returned to a gasification furnace, and further, inert gas is adopted as a conveying medium, so that the conveying of the fly ash is more stable;
(8) According to the coal gasification process, the coal gasification system is adopted to produce gas, the fly ash in the coal gas is separated in two sections, the fly ash with larger particle size is directly sent back to the gasification furnace to react, and the fly ash with smaller particle size is firstly mixed with the reaction medium and then returned to the gasification furnace to react, so that the work load of a dust removing device is reduced, the possibility of blocking during the fly ash conveying is reduced, and on the other hand, the fly ash particles with small particle size are fully mixed with the reaction medium, and the treatment efficiency of the fly ash particles with small particle size is improved.
Drawings
FIG. 1 is a schematic diagram of the operation of the coal gasification system of the present invention;
FIG. 2 is a schematic view of the structure of the fly ash burner of the present invention;
FIG. 3 is a cross-sectional view of a fly ash burner of the present invention;
in the figure: 1. a gasification furnace; 2. a cyclone separator; 3. a preheater; 4. a waste heat recoverer; 5. a dust removal device; 6. a powder bin; 7. an intermediate tank; 8. a feed tank; 9. a feeder; 10. a fly ash burner; 11. a slag extractor; 12. a gasifying agent channel; 13. a steam channel; 14. a coal dust channel; 15. a premixing zone; 16. and a cooling water passage.
Detailed Description
The invention is further described below in connection with specific embodiments and the accompanying drawings.
Example 1
As shown in fig. 1, a coal gasification system comprises a gasification device, a heat exchange device and a dust removal device 5 which are sequentially connected. The gasification device is equipment for carrying out gasification reaction on coal, the heat exchange device is used for cooling high-temperature coal gas generated by the gasification device and recovering heat, the dust removal device 5 is used for removing fly ash particles in the coal gas, improving the cleanliness of the coal gas, collecting the removed fly ash particles and then conveying the collected fly ash particles back to the gasification device for secondary reaction, and improving the carbon conversion rate and the coal gas yield of the whole system. The operation of the system will be explained in detail by describing the specific structure and connection relationship of each device, respectively.
In this embodiment, the gasification furnace 1 is used as a gasification device, and the gasification furnace 1 is a fluidized bed gasification furnace commonly used in the market. The gasification furnace 1 is provided with a coal inlet, a gasifying agent inlet, a slag discharging port, a coal gas outlet and a material returning port. Wherein, the coal inlet is connected with the coal feeder and is used for receiving the coal; the gasifying agent inlet is connected with an external gasifying agent supply device and is used for introducing gasifying agent for coal reaction into the gasifying furnace 1, and steam and air are adopted as gasifying agent for primary reaction of coal dust in the embodiment; the slag discharging port is used for discharging the reacted coal slag out of the gasification furnace 1, is arranged at the lower part of the gasification furnace 1, is connected with a slag extractor 11 through a pipeline, and has higher slag discharging efficiency because the slag extractor 11 adopts a spiral slag extractor; the gas outlet is arranged at the upper part of the gasification furnace 1, so that the gas can be conveniently and better led out of the furnace body, the gas outlet is sequentially connected with a heat exchange device and a dust removal device 5 through pipelines, the gas outlet on the dust removal device 5 is connected with downstream gas storage equipment, the discharge port is connected with a return port on the gasification furnace 1 through a pipeline, and the removed fly ash particles are returned to the gasification furnace 1 for secondary reaction.
In general, some high-temperature-resistant dust removal devices have not good dust removal effect on small-particle-size fly ash particles under the condition of ensuring that the self-bearing temperature is high, and some special dust removal devices capable of resisting high temperature and removing small-particle-size fly ash particles have too high cost. By installing a heat exchange device between the gasification furnace 1 and the dust removal device 5, the temperature of the discharged gas can be reduced, so that some dust removal devices 5 with low cost and good dust removal effect are selected. In this embodiment, a bag type dust collector commonly found in the market is adopted as the dust collector 5, which can remove and collect most of fly ash particles mixed in the coal gas, and especially for fine fly ash particles with particle diameters below 1 micron, the removal rate is as high as 99%.
In this embodiment, the heat exchange device includes a preheater 3 and a waste heat recoverer 4. Wherein, the inlet end of the preheater 3 is communicated with the gas outlet of the gasification furnace 1, the outlet end is communicated with the inlet end of the waste heat recoverer 4, and the outlet end of the waste heat recoverer 4 is communicated with the inlet end of the dust collector 5. By adopting the two-section step-by-step cooling mode, the cooling effect on the coal gas is better, and the heat in the hot coal gas can be effectively recovered and used as the heating aspect of other works, so that the heat efficiency of the whole system is improved, the condition that the workload of single equipment is overlarge is avoided by step cooling, and the probability of equipment failure is reduced.
It should be noted that, since the fly ash particles collected by the dust collector 5 have a small particle size, high volatile matter and difficult ignition, the reaction efficiency after the fly ash particles are returned to the gasification furnace 1 is low, and coking phenomenon is liable to occur in the gasification furnace 1, which greatly affects the coal gasification efficiency of the gasification furnace 1. In response to this problem, the inventors devised a fly ash burner 10 that improves the efficiency of the fly ash reaction. As shown in fig. 1 to 3, the fly ash burner 10 is installed at a return port of the gasification furnace 1, has a multi-layer sleeve structure, and comprises a coal dust channel 14, a steam channel 13, a gasifying agent channel 12 and a cooling water channel 16 from inside to outside.
The inlet end of the pulverized coal channel 14 is connected to the discharge port of the dust collector 5, the inlet end of the steam channel 13 is connected to the steam outlet of the steam device (the common steam generator in the market can be used as the steam device in this embodiment), the inlet end of the gasifying agent channel 12 is connected to the air source (both oxygen-enriched air and pure oxygen can be used, the concentration of the oxygen-enriched air can be adjusted according to the actual situation, in this embodiment, the oxygen-enriched air with the concentration of 50% is adopted, the reaction efficiency of the fly ash is improved, the cost is saved as much as possible, and the use effect is better), and the inlet end of the cooling water channel 16 is connected to the water source (the water source temperature can be selected according to the actual situation, and the normal temperature is generally adopted).
In addition, a premixing area 15 is arranged on one side of the fly ash burner 10, which is contacted with the discharge port of the gasifier 1, and the premixing area 15 is used for providing a space for fully mixing the fly ash with steam and oxygen-enriched air, so that the mixing time of the fly ash with the steam and the oxygen-enriched air is prolonged. The outlet ends of the pulverized coal channel 14, the steam channel 13 and the gasifying agent channel 12 are all communicated with the premixing area, while the cooling water channel 16 is not communicated with the premixing area 15, so that the pulverized coal channel is only used for cooling the pulverized fuel nozzle 10, and the pulverized fuel nozzle 10 is prevented from being damaged due to overhigh temperature. In order to further enhance the mixing of the fly ash, steam and oxygen-enriched air, the outlet ends of the steam channel 13 and the gasifying agent channel 12 are provided with inclined-plane necking structures, the inclined plane angle is within 30-50 degrees, the embodiment is 35 degrees, and the fly ash, steam and oxygen-enriched air are more fully mixed under the angle.
A coal gasification process adopts a coal gasification system of the embodiment to produce gas, which can separate and collect fly ash from coal gas and return the fly ash to a gasification furnace 1 for re-reaction, and has high reaction efficiency after the fly ash returns to the furnace and no coking phenomenon. A detailed description of the specific process of the coal gasification process is provided below.
1. Gasification section
When the coal gasification system works, coal materials react in the gasification furnace 1 and generate high-temperature coal gas, the temperature of the coal gas is about 1000 ℃, and the generated high-temperature coal gas is discharged from a coal gas outlet of the gasification furnace 1 and enters a heat exchange section.
2. Heat exchange section
The gas generated in the gasification section is cooled by the preheater 3 and the waste heat recoverer 4 in sequence, the temperature of the cooled gas is about 180 ℃, and the cooled gas enters the dust removal section.
3. Dust removal section
The coal gas after heat exchange enters a dust removing device 5, fly ash particles mixed in the coal gas are removed and collected by the dust removing device 5, and the clean coal gas after dust removal is sent to downstream coal gas storage equipment.
4. Fly ash re-furnace working section
The fly ash particles collected in the dust removing section are conveyed to a coal dust channel 14 in the burner 10 through pipeline fly ash, fully mixed with steam and oxygen-enriched air in a premixing zone 15, and then enter the gasifier 1 for secondary reaction.
The coal gasification process of the embodiment effectively improves the reaction efficiency of the fly ash after returning to the gasification furnace 1 by fully mixing the fly ash with steam and oxygen-enriched air, and avoids the conditions of difficult reaction and coking after returning to the furnace under the conventional condition.
Example 2
When the coal gasification system of example 1 is in operation, fly ash particles in coal gas can be separated and collected by the dust collector 5, and the collected fly ash particles are sent to the fly ash burner 10 through a pipeline to be mixed with steam and oxygen-enriched air, and then sent to the gasification furnace 1 for reaction. However, since the amount of fly ash particles collected per unit time is not fixed, the speed of transporting the fly ash particles to the fly ash burner 10 through the pipe is not uniform, thereby affecting the mixing effect of the fly ash particles with steam and oxygen-enriched air and reducing the reaction efficiency after the fly ash is returned to the furnace. In addition, fly ash particles have certain adhesiveness, the pressure in the pipe is not stable enough when the fly ash particles are conveyed in the pipeline, and the fly ash is easy to be adsorbed on the inner wall of the pipeline to cause blockage.
In order to solve the above problems, the coal gasification system of the present embodiment provides a pneumatic conveying apparatus in addition to embodiment 1. The pneumatic conveying device is arranged between a dust removing device 5 and a fly ash burner 10, and the dust bin 6, the intermediate tank 7, the feed tank 8 and the feeder 9 are sequentially connected from the dust removing device 5 to the fly ash burner 10. Wherein, the powder bin 6 is used for collecting and temporarily storing the fly ash particles separated by the dust removing device 5, and the middle tank 7 plays a role in stabilizing pressure and storing the fly ash particles, so that the fly ash can continuously and stably enter the feeding tank 8, and the feeding tank 8 can be used by using a conventional pulverized coal feeding tank. The feeder 9 is arranged at the outlet of the feeder tank 8, and the feeder 9 is a constant-weight feeder commonly used in the prior art, so that the purpose of quantitatively conveying fly ash particles can be achieved.
The embodiment also provides a coal gasification process, and the coal gasification system of the embodiment is adopted, so that part of improvement is made on the fly ash furnace return working section on the basis of the embodiment 1, and the process of the improved fly ash furnace return working section is as follows:
the fly ash particles collected in the dust removing section pass through a powder bin 6, a middle tank 7, a feed tank 8 and a feeder 9 in sequence, are continuously and quantitatively sent to a fly ash burner 10 under the action of inert gas (nitrogen is adopted in the embodiment) to be mixed with steam and oxygen-enriched air, and then enter a gasification furnace 1 to carry out secondary reaction.
The gasification process of the embodiment continuously and quantitatively conveys the fly ash particles into the fly ash burner 10 through the pneumatic conveying device, which is favorable for fully mixing the fly ash particles with steam and oxygen-enriched air, thereby improving the reaction efficiency after the fly ash returns to the furnace.
Example 3
In the coal gasification system of example 2, fly ash particles can be continuously and quantitatively fed to the fly ash burner 10 by a pneumatic conveyor, and a bag filter is used as the dust collector 5, and the bag filter has a good separation effect on fly ash particles, and even the separation rate of fly ash particles having a particle diameter of 1 μm or less can reach 99%. However, this approach also presents some problems:
(1) Because the bag type dust collector has excellent dust removing effect, the amount of the fly ash particles separated and collected in unit time is relatively large, and a large amount of fly ash particles are easier to cause the blockage of a transportation pipeline on one hand, and are unfavorable for fully mixing with steam and oxygen-enriched air in the fly ash burner 10 on the other hand, so that the reaction efficiency of the fly ash after being returned to the furnace is influenced;
(2) Only a single bag type dust collector with good dust removing effect is adopted to separate fly ash particles in coal gas, the work load of the bag type dust collector is relatively large, and some damages and even faults are easy to generate under the long-time working condition, so that the dust removing effect is influenced;
(3) Because the excellent dust removal effect on coal gas is required to be ensured, a bag type dust collector is adopted, but because the high temperature resistance of the bag type dust collector and the fly ash burner 10 is not strong, a heat exchange device is required to be additionally arranged before the dust removal process, so that the temperature of the finally collected fly ash particles is the fly ash particles cooled by the heat exchange device. The high temperature has an effect of enhancing the reaction efficiency of the fly ash particles, and the cooling measure has an effect on the reaction efficiency of the fly ash after being returned to the furnace.
In view of the above problems, the inventors have found in practice that the high temperature of the larger fly ash particles after they are discharged from the gasification furnace 1 does not need to be fully mixed with the reaction medium in advance, and the reaction efficiency of the reaction of the fly ash particles after they are returned directly to the gasification furnace 1 for re-reaction is still high. In this connection, in this embodiment, on the basis of the coal gasification system of embodiment 2, a high temperature resistant cyclone separator 2 is provided between the gasification furnace 1 and the heat exchange device, and another material return port is provided above the original material return port (or the fly ash burner 10) on the gasification furnace 1. The gas inlet of the cyclone separator 2 is communicated with the gas outlet of the gasifier 1, the gas outlet of the cyclone separator is connected with the inlet end of the heat exchange device, the discharge port of the cyclone separator is directly communicated with the other material returning port on the gasifier 1 through a pipeline, and the parameters of the cyclone separator 2 are set to separate fly ash particles with the particle size of more than 100 microns.
The embodiment also provides a coal gasification process, and the coal gasification system of the embodiment is adopted, and a fly ash pretreatment working section is additionally arranged on the basis of the coal gasification process of the embodiment 2, wherein the working process of the fly ash pretreatment working section is positioned between the gasification working section and the heat exchange working section, and the specific process is as follows:
the high-temperature gas generated in the gasification working section is discharged from a gas outlet of the gasification furnace 1 and then is conveyed to the high-temperature resistant cyclone separator 2. The cyclone separator 2 is set to separate the fly ash particles with the particle size of more than 100 microns, separates and collects the fly ash particles with the particle size of more than 100 microns in the coal gas, directly conveys the fly ash particles to the gasifier 1 for reaction, and the separated high-temperature coal gas enters a heat exchange section.
In this way, a part of the fly ash particles are separated in advance, the work load of the dust removing device 5 is reduced, and the fly ash particles with larger particle size are directly returned to the gasification furnace 1 through the cyclone separator 2, so that the probability of blocking the fly ash particles in the subsequent pipeline is also reduced. In addition, since the fly ash particles with a large particle diameter of 100 μm or more contain a large amount of carbon residue and the temperature thereof is extremely high, the reaction efficiency can be kept high after the fly ash particles are returned to the gasification furnace 1, and the coking phenomenon can not occur. In the process of entering the fly ash burner 10, the small-particle-size fly ash particles are fully mixed with steam and oxygen-enriched air due to the reduction of the unit conveying amount of the fly ash particles and the reduction of the particle size, so that the reaction efficiency of the small-particle-size fly ash particles after returning to the furnace is further improved.
In summary, the coal gasification system and the gasification process according to the present embodiment can collect fly ash particles and return the fly ash particles to the gasification furnace 1 for re-reaction, thereby improving the carbon conversion rate of the system. The embodiment effectively prevents the blockage of the fly ash particles in the conveying pipeline, and the fly ash particles are returned to the gasification furnace 1 for reaction twice, so that the reaction efficiency of the fly ash particles is greatly improved.
The examples of the present invention are merely for describing the preferred embodiments of the present invention, and are not intended to limit the spirit and scope of the present invention, and those skilled in the art should make various changes and modifications to the technical solution of the present invention without departing from the spirit of the present invention.
Claims (8)
1. The utility model provides a coal gasification system, includes gasifier (1) and dust collector (5), the inlet end of dust collector (5) communicates its characterized in that with the coal gas outlet of gasifier (1):
the device also comprises a fly ash burner (10), wherein the fly ash burner (10) comprises a gasifying agent channel (12), a steam channel (13) and a coal dust channel (14); the inlet end of the gasifying agent channel (12) is connected with an air source, the inlet end of the steam channel (13) is connected with a steam device, and the inlet end of the coal dust channel (14) is connected with a discharge port of the dust removing device (5); the outlet ends of the gasifying agent channel (12), the steam channel (13) and the coal powder channel (14) are communicated with a premixing zone (15) of the fly ash burner (10), and the premixing zone (15) is connected with a material returning port of the gasifying furnace (1);
the pulverized coal channel (14), the steam channel (13) and the gasifying agent channel (12) are of sleeve structures, and the pulverized coal channel (14), the steam channel (13) and the gasifying agent channel (12) are sequentially arranged from inside to outside; the outlet end of the gasifying agent channel (12) and the outlet end of the steam channel (13) are of a necking structure;
also comprises a cyclone separator (2); the air inlet end of the cyclone separator (2) is communicated with the gas outlet of the gasifier (1), the air outlet end of the cyclone separator is communicated with the inlet end of the heat exchange device, and the discharge port of the cyclone separator is communicated with the material return port of the gasifier (1).
2. The coal gasification system according to claim 1, wherein: the outside of gasifying agent channel (12) in fly ash nozzle (10) still is provided with cooling water channel (16), cooling water channel (16) do not communicate with premixing area (15).
3. The coal gasification system according to claim 1, wherein: the heat exchange device is also included; the heat exchange device comprises a preheater (3) and a waste heat recoverer (4); the inlet end of the preheater (3) is communicated with a gas outlet of the gasifier (1), and the outlet end of the preheater is communicated with the inlet end of the waste heat recoverer (4); the outlet end of the waste heat recoverer (4) is communicated with the inlet end of the dust removing device (5).
4. A coal gasification system according to claim 3 wherein: the dust removing device (5) is a bag type dust remover.
5. The coal gasification system according to claim 3 or 4, wherein: the pneumatic conveying device is also included; the inlet end of the pneumatic conveying device is connected with a discharge port of the dust removing device (5), and the outlet end of the pneumatic conveying device is connected with the inlet end of the coal dust channel (14); the pneumatic conveying device comprises a powder bin (6), a feeding tank (8) and a feeder (9) which are connected in sequence; an intermediate tank (7) is also arranged between the powder bin (6) and the feeding tank (8); the inlet end of the intermediate tank (7) is communicated with the discharge port of the powder bin (6), and the outlet end of the intermediate tank is connected with the inlet end of the feed tank (8).
6. The coal gasification system of claim 5, wherein: the pneumatic conveying device conveys the fly ash to a fly ash burner (10) through inert gas.
7. A coal gasification process of the coal gasification system of any one of claims 1-6, comprising the steps of:
gasification section: conveying the coal material to a gasification furnace (1) for gasification reaction, and discharging generated coal gas from a coal gas outlet of the gasification furnace (1);
heat exchange section: the gas generated by the gasification working section sequentially enters a preheater (3) and a waste heat recoverer (4) for heat exchange, and then enters a dust removal working section;
dust removal section: the gas subjected to heat exchange enters a dust removing device (5), and the gas subjected to dust removal is conveyed to downstream gas storage equipment;
and (3) a fly ash re-furnace working section: the fly ash separated by the dust removing section is conveyed to a fly ash burner (10), and the fly ash is mixed with a reaction medium in the fly ash burner (10) and then enters a gasification furnace (1) for reaction.
8. The coal gasification process according to claim 7, wherein:
the method also comprises a fly ash pretreatment section: the gas generated by the gasification working section is discharged from a gas outlet of the gasification furnace (1) and then enters a cyclone separator (2), the cyclone separator (2) separates fly ash particles with the particle size of more than 100 microns and directly conveys the fly ash particles to the gasification furnace (1) for reaction, and the separated gas enters a heat exchange working section.
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| CN112940789A (en) * | 2021-01-26 | 2021-06-11 | 中国华能集团清洁能源技术研究院有限公司 | Two-section gasification furnace with high slag capturing rate and waste boiler system |
| CN113355136B (en) * | 2021-06-25 | 2022-11-15 | 宁夏神耀科技有限责任公司 | Nozzle system with steam as carrier flow and reactant and material conveying method |
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