CN110791326A - Circulating fluidized bed gasification device with gasification auxiliary bed and gasification method - Google Patents

Abstract

The invention provides a circulating fluidized bed gasification device with an auxiliary gasification bed and a gasification method, the gasification device comprises: a gasification furnace (1), and a fuel inlet, A gasification agent inlet, a return gas inlet, a furnace gas outlet, a bottom slag outlet and a material return outlet; a gas-solid separator (2), the inlet of the gas-solid separator (2) and the exhaust of the gasifier (1) and the gasification auxiliary bed, the gasification auxiliary bed includes a circulating material inlet, a gasification agent inlet, a return gas outlet and a return carbonaceous material outlet, and the circulating material inlet of the gasification auxiliary bed is connected to the gas solids. The solid phase outlet of the separator (2) is communicated with, the returned gas outlet of the gasification auxiliary bed is communicated with the returned gas inlet of the gasifier (1), and the returned carbonaceous material outlet of the gasification auxiliary bed is connected to the gasification auxiliary bed. The material return ports of the gasifier (1) are communicated with each other. According to the gasification apparatus and the gasification method of the present invention, the carbon conversion rate of the gasification apparatus can be improved.

Description

Circulating fluidized bed gasification device with gasification auxiliary bed and gasification method

technical field

The invention relates to the technical field of fuel gasification, in particular to a circulating fluidized bed gasification device with an auxiliary gasification bed and a circulating fluidized bed gasification method with an auxiliary gasification bed.

Background technique

Coal gasification is one of the core technologies of clean and efficient utilization of coal, and it is the basis for the development of coal-based chemical process industries such as coal-based chemicals, coal-based clean fuels, industrial gas and polygeneration systems.

The current coal gasification technology can be divided into fixed bed gasification technology, fluidized bed gasification technology and entrained bed gasification technology according to the gas-solid flow form. The fixed bed coal gasification technology uses lump coal as raw material. There are obvious drying layers, pyrolysis layers, gasification layers and combustion layers in the gasifier. The slag discharge temperature and gas outlet temperature are low, and the thermal efficiency of the system is high. The gasification rate is slow, the gasification intensity is low, the gasification scale of a single furnace is small, and the crude gas contains pollutants such as phenols and tars, which increases environmental protection investment and operating costs. The entrained-flow coal gasification technology uses pulverized coal less than 100 μm as the raw material, the reaction temperature is high, the liquid slag is used, the gasification intensity is large, and the single furnace treatment scale is large. However, due to the high gasification temperature, pure oxygen is generally used as the gasification agent. High oxygen consumption, high equipment investment and operating costs.

The fluidized bed coal gasification technology can use 0-10mm crushed coal, does not require a complex coal preparation system, and the cost of coal preparation is low; the gasification intensity is high, generally 2 to 3 times that of the fixed bed; air can be used as a gasification agent ; High outlet temperature of crude gas, almost free of tar and phenols. Compared with the traditional fluidized bed coal gasification technology, the circulating fluidized bed coal gasification technology developed in recent years has the characteristics of high circulation rate, greater gasification intensity, more complete gas-solid mixing, and more uniform reaction temperature. The scale of chemical conversion is larger and the adaptability to coal is stronger, but the carbon content in fly ash is high, and the carbon conversion rate needs to be further improved.

In the existing circulating fluidized bed coal gasification technology, the lower part of the gasifier furnace has the highest temperature and the largest combustion share, but the material has low carbon content and high particle concentration; Gradually decreased, the carbon content of the material increased, but the particle concentration decreased. In order to avoid slagging, the temperature of the lower part of the furnace is limited, so the range of raising the overall temperature of the gasifier by increasing the temperature of the lower part of the furnace is limited, and the effect on improving the gasification efficiency is limited. Although the temperature of the area can be increased by introducing secondary air into the area with high carbon content in the furnace through the classification of the gasifying agent, the particle concentration in this area is relatively low, and the air or oxygen introduced preferentially reacts with the gas, but not with the gas. The carbon reaction probability in the solid material is small, and the promotion effect on improving the carbon conversion rate and cold gas efficiency of the system is not significant enough. After the gasification reaction of the gasifier, most of the solid materials are captured by the cyclone separator and returned to the furnace through the circulation loop; while the uncaptured fine powder ash leaves the gasification reaction system. The carbon content of the solid material returned to the furnace and the fine powder ash are high (the mass fraction of carbon in the solid material returned to the furnace is 50% to 80%, and the mass fraction of carbon in the fine powder ash is within the range of 30% to 50%. ).

To sum up, among the existing circulating fluidized bed coal gasification technologies, the lower part of the gasifier has the highest ash content and the highest gasification temperature, and the gasifier temperature and ash content gradually decrease from the bottom to the top of the gasifier along the height direction. . In order to avoid slagging, the temperature of the lower part of the furnace should not be too high, and the temperature is limited. Therefore, the range of increasing the overall temperature of the gasifier by increasing the temperature of the lower part of the furnace is limited. In the upper part of the furnace where high temperature is required to promote the gasification reaction of carbon and carbon dioxide, the temperature is limited, resulting in a low carbon conversion rate in the circulating fluidized bed gasifier and a high carbon content in the fine powder ash, which is not conducive to circulating fluidized bed coal gasification technology application. Although the temperature distribution in the height direction of the gasifier furnace can be changed by grading air distribution, so that the operating temperature of the gasifier is no longer limited by the temperature in the lower part of the furnace, but the oxygen or air introduced by the grading air distribution preferentially reacts with the gas, and reacts with the gas. The reaction probability of carbon in this area is very small, and the effect of promoting the gasification reaction performance of the system is not significant enough. Although the fine powder ash discharged from the gasifier can be processed into high-temperature gas and ash by building another high-temperature reaction device, another system needs to be built, which greatly increases equipment investment and operating costs, and may affect the circulating fluidized bed. Stable operation of gasifier and adaptability of coal types.

SUMMARY OF THE INVENTION

The purpose of the present invention is to at least partially overcome the defects of the prior art, and to provide a circulating fluidized bed gasification device with an auxiliary gasification bed and a circulating fluidized bed gasification method with an auxiliary gasification bed, which can Improve the carbon conversion rate of the gasifier.

Another object of the present invention is to provide a circulating fluidized bed gasification device with an auxiliary gasification bed and a circulating fluidized bed gasification method with an auxiliary gasification bed, so as to reduce the carbon content of the fine ash.

The purpose of the present invention is also to provide a circulating fluidized bed gasification device with an auxiliary gasification bed and a circulating fluidized bed gasification method with an auxiliary gasification bed. While improving the carbon conversion rate of the system, equipment investment is also required. And the operating cost is low, and the adaptability of circulating fluidized bed coal gasification coal is not reduced.

In order to achieve the above-mentioned purpose or one of the purposes, the technical solution of the present invention is as follows:

A circulating fluidized bed gasification device with an auxiliary gasification bed, the gasification device comprising:

The gasifier is provided with a fuel inlet, a gasification agent inlet, a return gas inlet, a furnace exhaust gas outlet, a bottom slag outlet and a material return outlet;

a gas-solid separator, the inlet of the gas-solid separator is communicated with the gas outlet of the exhaust furnace gas of the gasifier; and

A gasification auxiliary bed, the gasification auxiliary bed includes a circulating material inlet, a gasification agent inlet, a return gas outlet and a return carbonaceous material outlet, and the circulating material inlet of the gasification auxiliary bed and the solid phase outlet of the gas-solid separator The gas return gas outlet of the auxiliary gasification bed is connected with the return gas inlet of the gasifier, and the carbonaceous material outlet of the gasification auxiliary bed is connected with the material return port of the gasifier.

According to a preferred embodiment of the present invention, a first-level material returning device is further provided between the gas-solid separator and the gasification auxiliary bed, and the first-level material returning device is respectively connected with the solid phase outlet of the gas-solid separator and the gasification auxiliary bed. connected to the circulating material inlet.

According to a preferred embodiment of the present invention, the gasification device further includes a secondary material returning device, and the secondary material returning device is respectively connected with the carbon-containing material outlet of the gasification auxiliary bed and the material returning port of the gasifier. connected.

According to a preferred embodiment of the present invention, the lower part of the gasifier has a shape that is reduced from top to bottom.

According to a preferred embodiment of the present invention, the height of the fuel inlet of the gasifier from the bottom of the gasifier is 1/2-1/4 of the total height of the gasifier.

According to a preferred embodiment of the present invention, the gasification auxiliary bed is a fluidized bed reactor.

According to a preferred embodiment of the present invention, the circulating material inlet of the auxiliary gasification bed and the outlet of the carbonaceous material returned to the furnace are respectively located on opposite sides of the side wall of the auxiliary gasification bed.

According to a preferred embodiment of the present invention, the secondary material returning device is located at the bottom of the auxiliary gasification bed, and the secondary material returning device is combined with the auxiliary gasification bed, so that the carbonaceous material outlet of the auxiliary gasification bed returns to the furnace It is directly connected to the inlet of the secondary return device.

According to a preferred embodiment of the present invention, the gasification device further includes an additional gas-solid separator and an additional return material device, the inlet of the additional gas-solid separator is connected with the gas-phase outlet of the gas-solid separator, and the additional gas-solid separator The outlet of the solid phase is connected with the inlet of the additional material returning device, and the outlet of the additional material returning device is connected with the inlet of the circulating material of the gasification auxiliary bed.

According to a preferred embodiment of the present invention, the carbon-containing material inlet of the high-temperature gasification auxiliary bed is located in the dense phase zone of the high-temperature gasification auxiliary bed, and a balance connected to the dilute phase zone of the high-temperature gasification auxiliary bed is set on the first-stage material returning device. Tube.

According to a preferred embodiment of the present invention, a gasification agent inlet is provided on the connecting pipe connecting the additional material returning device and the gasification auxiliary bed.

According to a preferred embodiment of the present invention, the position of the return gas inlet of the gasifier is higher than the position of the return gas inlet of the gasifier.

According to a preferred embodiment of the present invention, the return gas inlet of the gasifier is arranged in the middle and upper part of the gasifier.

According to a preferred embodiment of the present invention, the primary returning device is a mechanical device or a non-mechanical device; and/or the secondary returning device is a mechanical device or a non-mechanical device.

According to a preferred embodiment of the present invention, the gasification agent inlet of the auxiliary gasification bed is arranged at the bottom of the auxiliary gasification bed, and the return gas outlet of the auxiliary gasification bed is arranged at the top of the auxiliary gasification bed.

According to a preferred embodiment of the present invention, the included angle between the jet direction of the gasification agent entering the gasification agent inlet on the connecting pipe and the moving direction of the material in the connecting pipe is an acute angle.

According to a preferred embodiment of the present invention, the gas-solid separator is a cyclone or an inertial separator, and the additional gas-solid separator is a cyclone.

According to a preferred embodiment of the present invention, the auxiliary gasification bed further includes a slag discharge port, and the slag discharge port is arranged at the bottom of the auxiliary gasification bed.

According to another aspect of the present invention, a circulating fluidized bed gasification method with an auxiliary gasification bed is provided, using the circulating fluidized bed gasification with an auxiliary gasification bed as described in any one of the preceding embodiments The device, the gasification reaction takes place in the gasification auxiliary bed (3).

According to a preferred embodiment of the present invention, the gasification method includes:

a) Passing the first gasification agent into the gasifier to undergo partial combustion and gasification reaction with the fed fuel and the returned carbonaceous material returned from the auxiliary gasification bed to generate first coal gas, first carbonaceous material and bottom slag ;

b) The first carbon-containing material is carried up by the first gas, and is heated by the returning gas from the gasification auxiliary bed, and the carbon in the first carbon-containing material further undergoes a gasification reaction with the first gas and the returning gas, The furnace gas is generated, and the first carbon-containing material after further reaction is converted into carbon-containing material, and flows to the gas-solid separator under the carrying of the furnace gas;

c) After the carbonaceous material and the furnace gas are separated by the gas-solid separator, the furnace gas and powder ash are discharged from the gas-phase outlet of the gas-solid separator, and the separated circulating material is returned to the auxiliary gasification bed;

d) The second gasification agent and the circulating material undergo a gasification reaction in the gasification auxiliary bed to generate return gas and return carbonaceous material; and

e) Returned gas and returned carbonaceous materials are respectively returned to the gasifier, and the bottom slag is discharged from the gasifier.

According to a preferred embodiment of the present invention, the mass ratio of steam to coal in the gasifier is 0.2-0.6, and the ratio of oxygen to coal is 0.2-0.5 m ³ /kg.

According to a preferred embodiment of the present invention, the ratio of air or oxygen to water vapor in the first gasification agent is adjusted, and the temperature of the lower part of the gasification furnace is controlled to be 850-950°C.

According to a preferred embodiment of the present invention, the fluidization velocity of the auxiliary gasification bed is 0.5 m/s to 2.5 m/s.

According to a preferred embodiment of the present invention, the temperature of the auxiliary gasification bed is controlled to be 50°C to 300°C higher than the temperature of the lower part of the gasifier.

According to a preferred embodiment of the present invention, the first gasifying agent is oxygen, air or water vapor, or a mixture of oxygen and water vapor, or a mixture of air and water vapor; and/or

The second gasifying agent is oxygen, air or water vapor, or a mixture of oxygen and water vapor, or a mixture of air and water vapor.

According to a preferred embodiment of the present invention, the first gasification agent introduced into the gasifier is fed in two stages from different positions of the gasifier.

According to the characteristics of carbon concentration distribution in the material circulation of the circulating fluidized bed coal gasification technology, the invention adds a high-temperature gasification auxiliary bed to the circulation loop, performs high-temperature gasification of solid materials with high carbon content, and converts the high-temperature solid materials generated by high-temperature gasification. The material is returned to the middle and lower part of the gasifier furnace, and the high-temperature gas generated by high-temperature gasification is passed into the middle and upper part of the gasifier, which strengthens the gasification reaction in the furnace, thus improving the carbon conversion rate and gas quality of the gasifier, and reducing the gasification. Carbon content of ash.

By adding a high-temperature gasification auxiliary bed to the circulation loop, the distribution law of the furnace temperature and carbon content of the existing circulating fluidized bed is changed, a low-temperature partial combustion zone is formed in the lower part of the furnace, and a gasification high-temperature zone is formed in the upper part of the furnace . This distribution law is conducive to strengthening the gasification reaction of the gasifier and avoiding slagging in the lower part of the furnace, which is conducive to the stable operation of the gasifier.

Compared with the scheme of processing fine powder ash by establishing a set of high temperature reaction device (molten state slag discharge), the process of the invention is simpler, the equipment investment and operation cost are lower, and no additional three wastes are generated; Or the scheme of returning high temperature flue gas or gas generated by gasification to the gasifier, the present invention is an open material circulation loop, there is no problem of ash accumulation, and the sensible heat carried by the fine powder ash is effectively used, so it can improve the system. At the same time of carbon conversion rate, it does not reduce the advantages of the adaptability of circulating fluidized bed coal gasification.

Description of drawings

1 is a schematic diagram of a circulating fluidized bed gasification device with an auxiliary gasification bed according to an embodiment of the present invention;

2 is a gasification process diagram of a circulating fluidized bed gasification device with an auxiliary gasification bed according to an embodiment of the present invention;

3 is a schematic diagram of a circulating fluidized bed gasification device with a gasification auxiliary bed according to another embodiment of the present invention; and

4 is a schematic diagram of a circulating fluidized bed gasification device with a gasification auxiliary bed according to yet another embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements. Furthermore, in the following detailed description, for convenience of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. Obviously, however, one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in diagram form in order to simplify the drawings.

The designers have found that the carbon conversion rate of the system can be increased through regasification or combustion reactions. A possible idea is to use a high-temperature reaction device to treat all the fine powder ash discharged from the system for high-temperature reaction treatment, which can improve the carbon conversion rate of the system. The circulating fluidized bed gasifier participates in the reaction and supplementary heat. At this time, if the gasifier and the high temperature reaction device are regarded as a system, the carbon conversion rate of the system has indeed been significantly improved, but it is necessary to build a high temperature reaction system. The cost and operating cost increase significantly, and the fly ash entrained by the incoming hot flue gas will lead to the accumulation of system ash, thus affecting the stability of the gasifier operation and the adaptability of coal types.

According to the general concept of the present invention, a circulating fluidized bed gasification device with an auxiliary gasification bed is provided, the gasification device includes: a gasifier, and a fuel inlet and a gasification agent inlet are arranged on the gasifier , return gas inlet, exhaust gas outlet, bottom slag outlet and material return port; gas-solid separator, the inlet of the gas-solid separator is communicated with the exhaust gas outlet of the gasifier; The auxiliary gasification bed includes a circulating material inlet, a gasification agent inlet, an outlet for returning gas, and an outlet for returning carbonaceous materials. The circulating material inlet of the auxiliary gasification bed is communicated with the solid phase outlet of the gas-solid separator. The return gas outlet of the auxiliary bed is communicated with the return gas inlet of the gasifier, and the return carbonaceous material outlet of the gasification auxiliary bed is communicated with the return material outlet of the gasifier.

It should be noted that the setting of the auxiliary gasification bed (or the auxiliary high-temperature gasification bed) of the present invention is different from the addition of a high-temperature reaction device. With the aid of the chemical furnace, there is no need to build a high-temperature reaction system, and the construction cost and operating cost are effectively controlled.

FIG. 1 is a schematic diagram of a circulating fluidized bed gasification apparatus with an auxiliary gasification bed according to an embodiment of the present invention. As shown in Figure 1, the circulating fluidized bed gasification device with the high-temperature gasification auxiliary bed includes a gasifier 1, a gas-solid separator 2, a primary return device 4, a high-temperature gasification auxiliary bed 3 and two connected sequentially. The secondary material returning device 5 , wherein the secondary material returning device 5 is connected with the gasifier 1 , and the high-temperature gasification auxiliary bed 3 communicates with the middle and lower parts of the gasifier 1 through the secondary material returning device 5 . Specifically, the gasifier 1 is provided with a fuel inlet, a gasification agent inlet, a return gas inlet, a furnace gas outlet, a bottom slag outlet and a material return outlet, and the gas-solid separator 2 is provided with an inlet, a gas phase outlet and The solid phase outlet, and the gasification auxiliary bed includes a circulating material inlet, a gasification agent inlet, a return gas outlet, and a return carbonaceous material outlet. The first-level material returning device 4 is arranged between the gas-solid separator 2 and the gasification auxiliary bed, and includes an inlet and an outlet. The circulating material inlet of the auxiliary gasification bed is connected, and the secondary material returning device 5 is arranged between the auxiliary gasification bed and the gasifier 1, including an inlet and an outlet, and the inlet and outlet of the secondary material returning device 5 are respectively connected with the The carbon-containing material outlet of the gasification auxiliary bed is connected with the material returning port of the gasification furnace 1 . The inlet of the gas-solid separator 2 is communicated with the exhaust gas outlet of the gasification furnace 1, and the circulating material inlet of the gasification auxiliary bed is connected to the solid phase outlet of the gas-solid separator 2 through the primary return device 4. The return gas outlet of the gasification auxiliary bed is communicated with the return gas inlet of the gasifier 1, and the return carbonaceous material outlet of the gasification auxiliary bed is connected to the gasifier 1 through the secondary return device 5. The return port is connected.

In the embodiment of FIG. 1 , the lower part of the gasifier is in a shape with a cross section that decreases from top to bottom, the gasification agent inlet can be arranged at the bottom and/or the lower part of the gasifier, and the height of the fuel inlet from the bottom of the gasifier is 1/2-1/4 of the total height of the gasifier, the high temperature gasification auxiliary bed 3 is a fluidized bed reactor. Optionally, the primary returning device and the secondary returning device may be mechanical devices or non-mechanical devices.

Optionally, the circulating material inlet of the high-temperature gasification auxiliary bed 3 and the return carbonaceous material outlet are located on opposite sides of the side wall of the high-temperature gasification auxiliary bed 3 respectively. In this way, it is beneficial to prolong the residence time of the solid material in the high-temperature gasification auxiliary bed and improve the gasification efficiency in the high-temperature gasification auxiliary bed.

In an optional embodiment, the carbonaceous material inlet of the high-temperature gasification auxiliary bed 3 is located in the dense phase zone of the high-temperature gasification auxiliary bed 3, and the first-stage material returning device 4 is provided with a dilute phase zone with the high-temperature gasification auxiliary bed 3 Connected balance tubes.

Advantageously, the position of the return gas inlet of the gasifier 1 should be higher than the position of the material return port of the gasifier 1 . For the high temperature gasification auxiliary bed, the gasification agent inlet of the gasification auxiliary bed is arranged at the bottom of the gasification auxiliary bed, and the return gas outlet of the gasification auxiliary bed is arranged at the top of the gasification auxiliary bed.

The present invention also provides a circulating fluidized bed gasification method with a high-temperature gasification auxiliary bed. The method adopts a circulating fluidized-bed gasification device with a high-temperature gasification auxiliary bed, comprising gasifiers 1 connected in sequence. , gas-solid separator 2, high temperature gasification auxiliary bed 3 and connected channels. As shown in Figure 2, the method steps are as follows:

a) Passing the first gasification agent A into the gasification furnace ₁ to undergo partial combustion and gasification reaction with the fed coal B and the high temperature carbonaceous material E1 returned from the high temperature gasification auxiliary bed 3 to generate the first coal gas and the first gasification - carbonaceous material, and bottom slag H;

b) The first carbon-containing material is carried by the first gas into the middle and upper part of the gasifier furnace, and is heated by the high-temperature gas F from the high-temperature gasification auxiliary bed 3. The carbon in the first carbon-containing material is combined with the first gas and the gas. The CO ₂ and water vapor in the high temperature coal gas F further undergo gasification reaction to generate coal gas C. At the same time, the first carbon-containing material after further reaction is converted into carbon-containing material E ₀ , and is carried by the coal gas C and flows to the gas-solid separator. 2;

c) After the carbonaceous material E ₀ and the coal gas C are separated by the gas-solid separator 2, the coal gas C and the fine dust D are discharged from the gas phase outlet, and the separated circulating material E ₂ returns to the high-temperature gasification auxiliary bed 3;

d) the second gasification agent G and the circulating material E ₂ undergo a gasification reaction in the high-temperature gasification auxiliary bed 3 to generate a high-temperature coal gas F and a high-temperature carbon-containing material E ₁ ;

e) The high temperature coal gas F enters the middle and upper part of the gasifier to react with the _first carbonaceous material, etc., the high temperature carbonaceous material E1 is returned to the gasifier, and the bottom slag H is discharged from the bottom of the gasifier.

In the above-mentioned gasification method, the mass ratio of steam and coal in the gasifier 1 is 0.2 to 0.6 kg/kg, and the ratio of oxygen to coal is 0.2 to 0.5 m ³ /kg. Advantageously, by adjusting the ratio of air or oxygen to water vapor in the first gasification agent A, the temperature of the lower part of the gasification furnace 1 is controlled to be 850-950°C. As mentioned above, the high temperature gasification auxiliary bed 3 is a fluidized bed reactor, and its fluidization speed is 0.5m/s～2.5m/s, and the temperature of the high temperature gasification auxiliary bed 3 is controlled to be higher than the temperature of the lower part of the gasifier 50℃～300℃. Controlling the temperature of the auxiliary gasification bed to be 50°C to 300°C higher than the temperature of the lower part of the gasifier is the purpose and the most fundamental idea of setting up the auxiliary bed for high temperature gasification.

According to an embodiment of the present invention, the first gasifying agent A may be oxygen, air or water vapor, or a mixture of oxygen and water vapor, or a mixture of air and water vapor, and the second gasifying agent G may be oxygen, air Or water vapor, or a mixture of oxygen and water vapor, or a mixture of air and water vapor. In addition, the first gasifying agent A introduced into the gasifier 1 may be fed from different positions of the gasifier 1 in two stages.

The lower part of the gasifier has a reduced cross-sectional shape, and the cross-sectional area is gradually reduced from top to bottom. A gasification agent inlet is provided at the bottom or the bottom and the lower part of the gasifier 1 for feeding the gasification agent into the circulating fluidized bed gasification device; a fuel inlet is provided on the gasifier for feeding the gasifier 1 Coal and other gasification raw materials are fed into the gasifier, and the height of the fuel inlet of the gasifier 1 from the bottom of the gasifier is 1/2 to 1/4 of the total height of the gasifier 1 . A material returning port communicated with the secondary material returning device 5 is provided in the lower middle and lower part of the gasifier 1 . The bottom of the gasifier 1 is provided with a slag discharge port for discharging the slag produced in the gasifier. The bottom of the gasifier is about the lowest part of the space formed by the wall of the gasifier, and the lower part of the gasifier is the wall of the gasifier near the bottom of the gasifier and the space enclosed by it.

The high temperature gasification auxiliary bed 3 is provided with a gasification agent inlet at the bottom, and a return gas outlet at the top, and a communication pipe is arranged between the return gas outlet and the middle or upper part of the gasifier, and the gasification reaction is carried out in the high temperature gasification auxiliary bed. The generated gas enters the gasifier through the communication pipe. In an optional embodiment, the circulating material inlet of the high-temperature gasification auxiliary bed 3 and the return carbon-containing material outlet are located on both sides of the high-temperature gasification auxiliary bed 3, so that it is beneficial to prolong the solid material in the high-temperature gasification auxiliary bed. residence time, and improve the gasification efficiency in the high temperature gasification auxiliary bed.

In an optional embodiment, the gasification raw material enters the gasifier from the fuel inlet of the gasifier 1, and undergoes a gasification reaction with the gasification agent added from the bottom and/or the lower part of the gasifier to generate carbonaceous materials and gas. A large amount of coal gas carries carbonaceous materials through the upper outlet of the gasifier 1 and enters the gas-solid separator 2 to complete the gas-solid separation. The captured particles are sent to the middle and lower part of the high-temperature gasification auxiliary bed 3 through the primary return device 4 dense area. Another part of the gasification agent is added into the system from the high-temperature gasification auxiliary bed 3, mixed with the material from the first-stage return material device 4, and gasification reaction occurs, producing high-temperature carbon-containing materials and high-temperature gas, which are then gasified in the high-temperature gasification auxiliary bed 3. The upper part of the gasifier 1 is provided with an outlet for returning gas, through which the high-temperature gas leaves the high-temperature gasification auxiliary bed, enters the middle and/or middle-upper part of the gasifier 1, and participates in the gasification reaction process in the gasifier 1; the high-temperature gasification auxiliary bed The high-temperature carbonaceous material in 3 returns to the lower part of the gasifier 1 with the secondary material returning device 5, and continues to participate in the gasification process in the gasifier. The qualified coal gas produced by gasification will carry a small part of fine powder ash that is not captured by the gas-solid separator and leave the system through the gas-phase outlet at the top of the gas-solid separator 2 .

On the basis of the existing circulating fluidized bed coal gasification material circulation loop, a high-temperature gasification auxiliary bed is added, and the circulating material separated by the separator is converted from low temperature to high temperature and then returned to the gasifier, thereby greatly improving the high carbon content and high carbon content. The temperature in the middle and upper part of the furnace chamber of the gasifier where the gasification endothermic reaction is the main reaction can increase the gasification intensity, thereby effectively reducing the carbon content of the fine powder ash, and compared with the solution of the fine powder ash by building another set of high temperature reaction device , the process of the invention is simpler, and the investment and operation costs are lower; at the same time, although the lower part of the gasifier has a high ash content, the temperature is low, which effectively avoids slagging in the lower part of the gasifier and ensures the safe, stable and efficient operation of the gasification system. .

The principle of the invention is: by analyzing the temperature distribution along the height direction of the gasifier in the circulating fluidized bed coal gasification process, the carbon content distribution of the solid particles, the particle concentration distribution and the reaction share distribution, the circulating fluidized bed circulation loop is set on the circulating fluidized bed circulation loop. A high-temperature gasification auxiliary bed is used to classify the carbon gasification reaction and gasification agent, so that the carbon-containing materials undergo gasification reaction in the gasifier and the high-temperature gasification auxiliary bed respectively during the circulation process. In the whole cycle process, the gasification agent is divided into two parts, one part is passed into the gasifier to participate in the conventional gasification reaction, and the other part is passed into the high-temperature gasification auxiliary bed, due to the high particle concentration in the high-temperature gasification auxiliary bed , the gasification agent will preferentially react with carbon, thus achieving further gasification of the gasification feedstock. In addition, after the gasification process in the high-temperature gasification auxiliary bed, the temperature of the solid material increases, and the high-temperature solid material returns to the middle and lower parts of the gasifier, so that a high-temperature gasification reaction zone is formed in the middle and lower regions of the gasifier; The high-temperature gas in the auxiliary gasification bed is passed into the middle and upper part of the gasifier to strengthen the reaction of carbon and carbon dioxide and the reaction of carbon and water vapor in the gasifier, reduce the carbon content and carbon dioxide concentration in the upper part of the gasifier, and increase the effective gas content. It solves the problems of low temperature in the middle and upper regions of the gasifier in the existing circulating fluidized bed coal gasification technology, low gasification reaction speed and high carbon content in the fine powder ash discharged from the system.

3 is a schematic diagram of a circulating fluidized bed gasification device with a gasification auxiliary bed according to another embodiment of the present invention. Compared with the embodiment shown in FIG. 1 , an additional gas-solid separator 6 is added after the gas-solid separator 2 , and correspondingly, a return material 7 is added, and the return material 7 is connected to the high-temperature gasification auxiliary bed 3 . connected. Specifically, the inlet of the additional gas-solid separator 6 is connected with the gas-phase outlet of the gas-solid separator 2, the solid-phase outlet of the additional gas-solid separator 6 is connected with the inlet of the additional return device, and the outlet of the additional return device is connected to the The circulating material inlet of the auxiliary gasification bed is connected. The gas-solid separator 2 can be a cyclone separator or an inertial separator (separation efficiency is 85% to 95%), the additional gas-solid separator 6 can be a cyclone dust collector (dust removal efficiency is 60% to 99%), 7 can be a non-mechanical return valve. The fine carbonaceous material J captured by the additional gas-solid separator 6 is transported to the high-temperature gasification auxiliary bed 3 through a non-mechanical return valve, and a gasification agent is set on the connecting pipeline from the non-mechanical return valve to the high-temperature gasification auxiliary bed 3 At the inlet, the third gasifying agent I is added into the connecting pipeline by using a jet. The angle between the jet direction of the third gasifying agent I and the moving direction of the fine carbonaceous material in the connecting pipe is at an acute angle, and the fine carbonaceous material J is rapidly mixed and reacted with the gasifying agent under the entrainment of the jet of the third gasifying agent I. Generate high temperature slag and gas. The high temperature slag and gas are passed into the dense phase area of the high temperature gasification auxiliary bed 3, and further participate in the gasification reaction in the high temperature gasification auxiliary bed. A slag discharge port is set at the bottom of the high temperature gasification auxiliary bed ₃ to discharge the coarse slag H system. The third gasifying agent I is air or a mixture of oxygen and water vapor. Under the condition that the materials captured by the two-stage gas-solid separator can be returned to the high-temperature gasification auxiliary bed 3 normally, the use of the two-stage gas-solid separator can improve the collection rate of fine dust and reduce the amount of fine dust The carbon taken out can further improve the carbon conversion rate of the system. Preferably, the fine carbonaceous material captured by the second-stage gas-solid separator is gasified with the gasification agent at a higher temperature, and the maximum temperature of the high-temperature slag entering the high-temperature gasification auxiliary bed can be higher than the flow temperature of the coal ash , which can be molten slag. The high temperature slag is dispersed under the turbulent impact of the material in the fluidized bed and exchanges heat with the material in the fluidized bed. The coarse slag H ₂ is discharged from the system through the slag discharge port at the bottom of the high-temperature gasification auxiliary bed, and the fine slag enters the gasifier 1 along with the high-temperature carbonaceous material E ₁ . While increasing the gasification reaction rate of the fine carbonaceous material, the ash agglomeration in this part of the fine carbonaceous material is discharged out of the system, so as to reduce the ash content in the circulation system. This method is especially suitable for the gasification of coal with relatively poor gasification activity and low ash content.

4 is a schematic diagram of a circulating fluidized bed gasification device with a gasification auxiliary bed according to yet another embodiment of the present invention. Among them, the high-temperature gasification auxiliary bed 3 is combined with the secondary return device 5, and the secondary return device 5 is located at the bottom of the high-temperature gasification auxiliary bed 3, so that the carbon-containing material outlet of the gasification auxiliary bed is connected to the secondary return device. The inlet of the feeding device 5 is directly connected, and the secondary feeding device 5 can be a non-mechanical feeding valve, or a combined device composed of a mechanical valve and a non-mechanical feeding valve. The second gasification agent G is uniformly fed from the circumferential direction of the high-temperature gasification auxiliary bed, so that the upper part where the second gasification agent G is fed is a fluidized bed, and the bottom combined with the material returning device is a moving bed. In this way, it not only ensures the full mixing and rapid reaction of the gasification agent and the carbon-containing material, and makes the temperature distribution of the high-temperature gasification auxiliary bed uniform, but also ensures the stable and controllable return of the carbon-containing material in the high-temperature gasification auxiliary bed to gasification. furnace. This structure effectively inhibits the carbon-containing material from leaving the high-temperature gasification auxiliary bed quickly due to short-circuit, and is conducive to the water vapor activation of the carbon-containing material in a high-temperature environment, further reducing the carbon content and fine powder of the gasifier bottom slag. Ash carbon content.

Further, the first gasifying agent A introduced into the furnace chamber of the gasifier can enter the gasifier in two stages, namely primary air and secondary air, wherein the primary air is fed from the bottom of the gasifier and is mainly used for gasification. For the fluidization at the lower part of the furnace and the combustion reaction of the bottom slag, the proportion of primary air is 40% to 70% of that of the first gasifying agent A; It is inclined upward, and the included angle with the horizontal plane is 15°～60°. The ratio of the secondary air is 30% to 60% of the first gasifying agent A. By classifying the gasifying agent introduced into the furnace chamber of the gasifier, the temperature and particle size distribution of the bottom slag in the lower part of the gasifier can be adjusted on the basis of satisfying the normal circulation of the circulating fluidized bed, so that the lower part of the gasifier is in the combustion reaction or Within the safe reaction temperature range of the partial combustion reaction, the problem of slagging caused by overheating in the lower part of the circulating fluidized bed gasifier is effectively solved.

According to the characteristics of carbon concentration distribution in the material circulation of the circulating fluidized bed coal gasification technology, the invention adds a high-temperature gasification auxiliary bed to the circulation loop, performs high-temperature gasification of solid materials with high carbon content, and converts the high-temperature solid materials generated by high-temperature gasification. The material is returned to the middle and lower part of the gasifier furnace, and the high-temperature gas generated by high-temperature gasification is passed into the middle and upper part of the gasifier, which strengthens the gasification reaction in the furnace, thus improving the carbon conversion rate and gas quality of the gasifier, and reducing the gasification. Carbon content of ash.

By adding a high-temperature gasification auxiliary bed to the circulation loop, the distribution law of the furnace temperature and carbon content of the existing circulating fluidized bed is changed, a low-temperature partial combustion zone is formed in the lower part of the furnace, and a gasification high-temperature zone is formed in the upper part of the furnace . This distribution law is conducive to strengthening the gasification reaction of the gasifier and avoiding slagging in the lower part of the furnace, which is conducive to the stable operation of the gasifier.

The process of the invention is simple, the equipment investment and operation cost are low, and three wastes are not generated; compared with the scheme of returning the high-temperature flue gas or coal gas generated by the combustion or gasification of fine powder to the gasifier, the invention is an open material cycle. There is no problem of ash accumulation in the loop, and the sensible heat carried by the fine ash is effectively used, so the carbon conversion rate of the system is improved, and the advantage of the adaptability of CFB coal gasification is not reduced.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that changes may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of applicability of the present invention is defined by the appended claims and their equivalents.

List of reference numbers:

1 Gasifier

2 Gas-solid separator

3 High temperature gasification auxiliary bed

4 first-level return device

5 Secondary return device

6 Additional gas-solid separator

7 Return feeder

A first gasification agent

B coal

C gas

D fine dust

E ₀ carbonaceous material

E ₁ High temperature carbonaceous material

E ₂ Recycled material

F high temperature gas

G Second gasifying agent

H Bottom slag

H ₂ coarse slag

I third gasifying agent

J Fine carbonaceous material.

Claims (17)

1. a circulating fluidized bed gasification device with an auxiliary gasification bed, wherein the gasification device comprises: A gasifier (1), provided with a fuel inlet, a gasification agent inlet, a return gas inlet, a furnace gas outlet, a bottom slag outlet and a material return outlet on the gasifier (1); a gas-solid separator (2), the inlet of the gas-solid separator (2) is communicated with the gas outlet of the exhaust furnace gas of the gasifier (1); and A gasification auxiliary bed (3), the gasification auxiliary bed comprises a circulating material inlet, a gasification agent inlet, a return gas outlet and a return carbonaceous material outlet, and the circulating material inlet of the gasification auxiliary bed is connected to a gas-solid separator ( 2) The solid phase outlet of the auxiliary gasification bed is communicated with the return gas outlet of the gasification auxiliary bed and the return gas inlet of the gasifier (1), and the returned carbonaceous material outlet of the gasification auxiliary bed is connected to the gasifier. (1) The return port is connected. 2. the circulating fluidized bed gasification device with auxiliary gasification bed according to claim 1, is characterized in that: Between the gas-solid separator (2) and the auxiliary gasification bed, a first-stage material returning device (4) is further arranged, and the first-stage material returning device (4) is respectively connected with the solid phase outlet and the gas-solid phase outlet of the gas-solid separator (2). The circulating material inlet of the chemical auxiliary bed is connected. 3. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 2, is characterized in that: The gasification device further comprises a secondary material returning device (5), the secondary material returning device (5) is respectively connected with the carbon-containing material outlet of the gasification auxiliary bed and the material returning port of the gasification furnace (1). connected. 4. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 1, is characterized in that: The lower part of the gasifier (1) has a shape that is reduced from top to bottom. 5. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 1, characterized in that: The height of the fuel inlet of the gasifier (1) from the bottom of the gasifier (1) is 1/2 to 1/4 of the total height of the gasifier (1). 6. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 1, characterized in that: The gasification auxiliary bed is a fluidized bed reactor. 7. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 1, characterized in that: The circulating material inlet of the auxiliary gasification bed and the outlet of the returned carbonaceous material are respectively located on opposite sides of the side wall of the auxiliary gasification bed. 8. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 3, characterized in that: The secondary material returning device (5) is located at the bottom of the auxiliary gasification bed, and the secondary material returning device (5) is combined with the auxiliary gasification bed, so that the outlet of the returned carbonaceous material of the auxiliary gasification bed is connected to the secondary gasification auxiliary bed. The inlets of the returning device (5) are directly connected. 9. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 3, characterized in that: The gasification device further comprises an additional gas-solid separator (6) and an additional material returning device, the inlet of the additional gas-solid separator (6) is connected with the gas-phase outlet of the gas-solid separator (2), and the additional gas-solid separator (2) The solid phase outlet of (6) is connected with the inlet of the additional material returning device, and the outlet of the additional material returning device is connected with the circulating material inlet of the gasification auxiliary bed. 10. The circulating fluidized bed gasification device with auxiliary gasification bed according to claim 9, characterized in that: A gasification agent inlet is arranged on the connecting pipeline connecting the additional material returning device and the gasification auxiliary bed. 11. A circulating fluidized bed gasification method with an auxiliary gasification bed, using the circulating fluidized bed gasification device with an auxiliary gasification bed according to any one of claims 1-10, characterized in that, The gasification reaction takes place in the gasification auxiliary bed (3). 12. The circulating fluidized bed gasification method with an auxiliary gasification bed according to claim 11, wherein the gasification method comprises: a) Passing the first gasification agent (A) into the gasifier (1) to undergo partial combustion and gasification reaction with the injected fuel and the returned carbonaceous material returned from the auxiliary gasification bed to generate the first coal gas, the first gas Carbonaceous materials and bottom slag (H); b) The first carbon-containing material is carried up by the first gas, and is heated by the returning gas from the gasification auxiliary bed, and the carbon in the first carbon-containing material further undergoes a gasification reaction with the first gas and the returning gas, generating furnace gas, and at the same time, the further reacted first carbon-containing material is converted into carbon-containing material (E ₀ ), and is carried by the furnace gas and flows to the gas-solid separator (2); c) After the carbonaceous material (E ₀ ) and the furnace gas are separated by the gas-solid separator (2), the furnace gas and powder ash are discharged from the gas-phase outlet of the gas-solid separator (2), and the separated circulating material (E ₂ ) Return to the gasification auxiliary bed; d) the second gasification agent (G) and the circulating material (E ₂ ) undergo a gasification reaction in the gasification auxiliary bed to generate return gas and return carbonaceous material; and e) Returned gas and returned carbonaceous materials are respectively returned to the gasifier, and the bottom slag (H) is discharged from the gasifier. 13. The circulating fluidized bed gasification method with auxiliary gasification bed according to claim 12, characterized in that: The mass ratio of steam and coal in the gasifier (1) is 0.2-0.6, and the oxygen-coal ratio is 0.2-0.5 m ³ /kg. 14. The circulating fluidized bed gasification method with auxiliary gasification bed according to claim 12, characterized in that: The ratio of air or oxygen and water vapor in the first gasification agent (A) is adjusted, and the temperature of the lower part of the gasification furnace (1) is controlled to be 850 to 950°C. 15. The circulating fluidized bed gasification method with auxiliary gasification bed according to claim 12, characterized in that: The fluidization velocity of the gasification auxiliary bed is 0.5m/s～2.5m/s. 16. The circulating fluidized bed gasification method with auxiliary gasification bed according to claim 12, characterized in that: The temperature of the auxiliary gasification bed is controlled to be 900-1300°C. 17. The circulating fluidized bed gasification method with auxiliary gasification bed according to claim 12, characterized in that: The temperature of the auxiliary gasification bed is controlled to be 50°C to 300°C higher than the temperature of the lower part of the gasifier.

Images