CN107983111B - System and method for capturing power plant flue gas carbon dioxide by rice husk gasification coupling sodium silicate - Google Patents

Abstract

The invention discloses a system and a method for capturing flue gas carbon dioxide of a power plant by rice husk gasification coupling sodium silicate, wherein the system comprises: sequential rice hull gasification coupling Na₂SiO₃The device comprises a preparation furnace, a charge device, an electric field auxiliary type fluidized reactor, a material separation device, a dissolver and a filter; wherein the rice hull is gasified and coupled with Na₂SiO₃The input end of the preparation furnace is synthetic raw material O₂And Na₂CO₃The inlet and the output of the solution are also connected with a first heat exchanger; a second heat exchanger is arranged in the electric field auxiliary type fluidized reactor; the material separation device is a two-stage cyclone separator which is connected in sequence, the output end of the upper part of the two-stage cyclone separator is connected with a third heat exchanger, the output ends of the lower part of the two-stage cyclone separator are connected back to the electric field auxiliary fluidized reactor, and a pipeline is additionally arranged and connected with a dissolver through a fourth heat exchanger; the output end of the filter is connected to the rice hull gasification coupling Na₂SiO₃And (4) preparing the furnace. The system is organically combined with a coal-fired power generation system, the temperature is kept constant by utilizing the heat exchange between the flue gas of a coal-fired power station and a bed body, and the investment and the energy consumption of the scheme are lower.

Description

A system of rice husk gasification coupled with sodium silicate to capture carbon dioxide from power plant flue gas and method

technical field

The invention relates to the field of pollutant emission reduction in the process of solid waste resource utilization and energy utilization, in particular to a system and method for capturing carbon dioxide from power plant flue gas by coupling rice husk gasification with sodium silicate, and belongs to carbon dioxide capture and emission reduction technical field.

Background technique

In recent years, global warming caused by greenhouse gas emissions has become the focus of the international community. Global warming will cause many disasters, such as: melting glaciers, rising sea levels, frequent occurrence of extreme weather, frequent emergence of new diseases, sharp decline in biodiversity, food crises, new political issues and wars.

China is the world's largest CO ₂ emitter, with a total annual emission of more than 9 billion tons, which has become the focus of global compliance. Coal-fired power plants are the largest source of _CO2 emissions, accounting for about 70% of China's total _CO2 emissions. Therefore, strengthening the research and reserve of CO ₂ emission reduction technology for coal-fired power plants has become the top priority of China's scientific and technological and economic development.

_CO2 capture is an effective way to control _CO2 emissions from coal-fired power plants. According to different technical routes, CO ₂ capture can be divided into pre-combustion capture technology, oxy-fuel combustion technology and post-combustion capture technology.

Due to the development, replacement and upgrade of equipment components, the post-combustion capture technology does not affect the operation status of the power plant itself. It can directly transform the existing power plant and put it into production quickly. It is most expected to achieve large-scale industrial application in the short term.

There are many branches of post-combustion capture technology, mainly including chemical absorption method, physical separation method, membrane separation method and low temperature separation method. Among many post-combustion capture technologies, chemical absorption methods (including wet and dry methods) have high _CO capture efficiency and good process adaptability, and are currently one of the technologies with great potential for large-scale _CO capture applications. Among them, the alkali metal-based absorbent dry _CO capture technology is regarded as a good decarbonization performance, low reaction energy consumption, renewable utilization, strong cycle stability, no corrosion to equipment and no secondary pollution. A promising new technology for _CO2 capture from power plant flue gas. However, the cost of alkali metal-based absorbents is still the biggest bottleneck restricting their large-scale application of _CO2 emission reduction.

In order to effectively reduce the cost of _CO2 capture technology, researchers have begun to try to use waste biomass materials as cheap carriers to synthesize _CO2 absorbents. Such as: oil palm tree-derived charcoal, coffee residue-derived charcoal, wood chip-derived charcoal, rice husk ash-derived porous silica gel, and biomass direct-fired power plant fly ash. Rice husk is a typical waste biomass material, and its silicon content in the ash after combustion can be as high as 90%, which has potential application value in the synthesis of porous silica gel and silica-alumina molecular sieve carrier to prepare CO ₂ absorbent. However, the process of preparing mesoporous silica gel and silica-alumina molecular sieve by purifying _SiO2 with rice husk ash is complicated and the cost is relatively high, so it is not suitable for large-scale application of _CO2 capture.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a system and method _of rice husk gasification coupled with _sodium silicate to capture carbon _dioxide from power plant flue gas. Efficient synthesis of Na ₂ SiO ₃ absorbent for CO ₂ capture from power plant flue gas. The method is simple and feasible, has high utilization efficiency of rice husks, and simple process flow, which can effectively reduce the CO ₂ capture cost of power plants, and can solve the problem of environmental pollution caused by the accumulation of rice husks. , and truly realize the resource utilization of waste. This scheme can significantly reduce the economic cost of large-scale _CO2 emission reduction, improve the technical feasibility, and provide a new way for low-cost _CO2 emission reduction.

The technical scheme provided by the present invention is as follows:

A system for rice husk gasification coupled with sodium silicate to capture carbon dioxide from power plant flue gas, comprising:

Rice husk gasification coupled with Na ₂ SiO ₃ preparation furnace, electric charger, electric field-assisted fluidized reactor, material separation device, dissolver, filter and four sets of heat exchangers; among which,

The input end of the rice husk gasification coupling Na ₂ SiO ₃ preparation furnace is the entrance of the synthetic raw material, O ₂ and Na ₂ CO ₃ solution, and the output end is connected to the charger and the first heat exchanger;

The output end of the charger is connected to the electric field-assisted fluidized reactor;

The electric field-assisted fluidized reactor is provided with a second heat exchanger, the output end of which is connected to a material separation device;

The material separation device is a two-stage cyclone separator, the upper output end of the first-stage cyclone separator is connected to the second-stage cyclone separator, the upper output end of the second-stage cyclone separator is connected to the third heat exchanger, and the lower part of the two-stage cyclone separator is connected The output ends are all connected back to the electric field-assisted fluidized reactor, and another pipeline is connected to the dissolver through the fourth heat exchanger;

The output end of the dissolver is connected to a filter;

The output end of the filter is connected back to the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace;

The fourth heat exchanger is additionally connected to the first heat exchanger, the first heat exchanger is additionally connected to the second heat exchanger, and the second heat exchanger is additionally connected to the electric field-assisted type. The bottom end of the fluidized reactor.

Preferably, the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace is a two-stage type, the upper input end is provided with a nozzle, which is the inlet of synthetic raw materials and O ₂ , and the lower input end is provided with a sprayer, which is Na ₂ CO ₃ solution entrance.

Preferably, insulating tapes are provided in the electric-electric-electricity-assisted and electric field-assisted fluidized reactor, and the required electric energy is provided inside the power plant.

A method of rice husk gasification coupled with sodium silicate to capture carbon dioxide from power plant flue gas, comprising the following steps:

Step 1) The synthetic raw materials are crushed first, and then sent to the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace, O ₂ is passed into the furnace for gasification, and Na ₂ CO ₃ solution is added at the same time, and Na 2 is synthesized after the reaction. ₂ SiO ₃ absorbent and combustible gas;

Step 2) The Na ₂ SiO ₃ absorbent enters the charger, and the powder is charged in the charger to form a charged Na ₂ SiO ₃ absorbent, and then enters the electric field-assisted fluidized reactor; the combustible gas passes through the first The heat exchanger is used to synthesize gas after heat exchange;

Step 3) The flue gas from the outlet flue of the dust collector in the power plant enters the system through the fourth heat exchanger, and is input from the bottom end of the electric field-assisted fluidized reactor after the third-stage heat exchange of the first heat exchanger and the second heat exchanger , reacts with charged Na ₂ SiO ₃ absorbent to remove CO ₂ in flue gas;

Step 4) The flue gas after removing CO ₂ and the reacted absorbent enter the two-stage cyclone separator for gas-solid separation, and a part of the separated absorbent is transported back to the electric field for assistance through the lower output end of the two-stage cyclone separator. type fluidized reactor, the unreacted Na ₂ SiO ₃ is recycled, and the other part is transported to the dissolver after heat exchange by the fourth heat exchanger; the separated flue gas has been freed of CO ₂ and can pass through the third heat exchanger After heat exchange, it is directly discharged into the chimney;

Step 5) Supplement water and Na ₂ CO ₃ powder from the outlet of the condenser to the dissolver, stir together with the Na ₂ SiO ₃ absorbent after heat exchange, and transport the formed mixed system to the filter for solid-liquid separation , the filtrate is returned to the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace for recycling, and the discharged filter residue rich in silicon and aluminum can be directly discharged and collected for the building materials industry.

Preferably, the gasification process in step 1) includes four stages of drying, pyrolysis, oxidation and reduction, wherein the drying temperature is 50-100°C, the pyrolysis temperature is 150-300°C, and the oxidation temperature is 300-1200°C , the reduction temperature is 600-900 ℃.

Preferably, the synthetic raw materials in step 1) are rice husks or wheat stems and leaves.

Preferably, the reaction temperature for synthesizing Na ₂ SiO ₃ in step 1) is 900°C;

Preferably, the reaction temperature for removing CO ₂ in step 3) is 700°C.

The beneficial effects of the present invention are as follows:

1. In the method of the present invention, waste biomass rice husks are used as raw materials, SiO ₂ carriers are formed by pyrolysis activation, and Na ₂ SiO ₃ absorbents are efficiently synthesized by Na ₂ CO ₃ solution modification to remove CO ₂ in power plant flue gas. At the same time, CO ₂ is converted into high-quality synthetic gas, and after the reaction, recyclable Na ₂ CO ₃ and silicon-rich aluminum materials are generated, turning waste into treasure, realizing efficient utilization of solid waste and saving the cost of system decarbonization.

2. The system of rice husk gasification coupled with sodium silicate to capture carbon dioxide from power plant flue gas provided by the present invention can be efficiently connected with coal-fired power plants. The heat required by the system is provided by a coal-fired power plant, and the energy can be efficiently recycled within the system. For example: the heat of rice husk gasification comes from the oxidation stage of rice husk, the heat of Na ₂ SiO ₃ absorbent synthesis is provided by the oxidation stage of rice husk, and the reaction heat of CO ₂ removal by Na ₂ SiO ₃ absorbent is provided by the flue gas of coal-fired power station It is provided by heat exchange with the circulating absorbent, synthetic gas and electric field-assisted fluidized reactor bed body after the reaction. The method makes full use of the heat of rice husks and the waste heat resources of coal-fired power plants, and improves the economy of system operation.

3. The rice husk gasification is coupled with the Na ₂ SiO ₃ sprayer in the preparation furnace, and the recovered Na ₂ CO ₃ solution is sprayed into the preparation furnace for recycling, and a low-temperature reduction zone is formed in the furnace at the same time, which can improve the gas efficiency of rice husk pyrolysis. It is beneficial to the synthesis of high-quality gas and effectively improves the economic benefits of the system.

4. The Na ₂ SiO ₃ powder is fully charged under the action of the electric field by the charger, and then the absorbent particles are smoothly fluidized by the electric field-assisted fluidization reactor, which improves the CO ₂ capture efficiency.

Description of drawings

Fig. 1 is the system structure schematic diagram of rice husk gasification coupled with sodium silicate to capture carbon dioxide from power plant flue gas of the present invention;

Explanation of main reference signs:

The equipment includes: 1. Conveyor; 2. Pulverizer; 3. Booster pump; 4. Rice husk gasification coupled Na ₂ SiO ₃ preparation furnace; 5. First heat exchanger; 6. Charger; 7. Electric field Auxiliary fluidized reactor; 8. Second heat exchanger; 9. Primary cyclone; 10. Secondary cyclone; 11. Third heat exchanger; 12, Fourth heat exchanger; 13. Dissolution 14. Filter.

Material cycle includes: A, synthetic raw material; B, pulverized synthetic raw material; C, oxygen; D, Na ₂ CO ₃ solution; E, combustible gas; F, synthetic gas after heat exchange; G, air; H, Na ₂ SiO ₃ absorbent; I, charged Na ₂ SiO ₃ absorbent; J, flue gas from the precipitator outlet flue; K, flue gas after CO ₂ removal; L, CO after gas-solid separation and heat exchange ₂ Flue gas after removal; M, part of absorbent after gas-solid separation; N, another part of absorbent after gas-solid separation; O, water from condenser outlet; P, Na ₂ CO ₃ powder; Q , filter residue.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1

As shown in Figure 1, the present invention provides a system of rice husk gasification coupled with sodium silicate to capture carbon dioxide from power plant flue gas, comprising:

Rice husk gasification coupled with Na ₂ SiO ₃ preparation furnace 4, charger 6, electric field-assisted fluidized reactor 7, material separation device, dissolver 13, filter 14 and four sets of heat exchangers; among them,

The input end of the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace 4 is the entrance of the synthetic raw material, O ₂ and Na ₂ CO ₃ solution, and the output end is connected to the charger 6 and the first heat exchanger 5;

The output end of the charger 6 is connected to the electric field-assisted fluidized reactor 7;

The electric field-assisted fluidized reactor 7 is provided with a second heat exchanger 8, the output end of which is connected to a material separation device;

The material separation device is a two-stage cyclone separator. The upper output end of the first stage cyclone separator 9 is connected to the second stage cyclone separator 10, and the upper output end of the second stage cyclone separator 10 is connected to the third heat exchanger 11. The lower output end of the cyclone separator is connected back to the electric field-assisted fluidized reactor 7, and another pipeline is connected to the dissolver 13 through the fourth heat exchanger 12;

The output end of the dissolver 13 is connected to the filter 14;

The output end of the filter 14 is connected back to the rice husk gasification coupling Na2SiO3 preparation furnace 4;

The fourth heat exchanger 12 is additionally connected to the first heat exchanger 5 with additional pipes, the first heat exchanger 5 is additionally connected to the second heat exchanger 8 with additional pipes, and the second heat exchanger 8 is additionally connected to the second heat exchanger 8 with additional pipes. The bottom end of the electric field-assisted fluidized reactor 7 .

Preferably, the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace 4 is mainly composed of a reaction bed, a nozzle and a sprayer, and is specifically designed as a two-stage type. The upper part is provided with a nozzle to spray crushed synthetic raw materials and oxygen, and the lower part is provided with a nozzle. The sprayer is sprayed with Na ₂ CO ₃ solution to ensure that the temperature in the furnace is reduced to the reduction reaction temperature range (900°C), so as to improve the gasification yield of synthetic raw materials. The gasification mainly includes four stages of drying, pyrolysis, oxidation and reduction: the drying temperature is 50-100°C, mainly for the precipitation of water; the pyrolysis temperature is 150-300°C, mainly for the precipitation of volatile matter, generating C , H ₂ , H ₂ O, CO, CH ₄ and CO ₂ and other products; the oxidation temperature is 300-1200°C, which can release a lot of heat and provide heat for the other three processes; the reduction temperature is 600-900°C, and the products are mainly CO and _H2 .

The raw materials for synthesizing the Na ₂ SiO ₃ absorbent in the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace 4 are biomass such as rice husks or wheat stems and leaves with high silicon content. The biomass with high silicon content is pyrolyzed and gasified at high temperature to form SiO ₂ , which reacts with the added Na ₂ CO ₃ solution to form a powdery Na ₂ SiO ₃ absorbent (Formula 1):

Na ₂ CO ₃ +SiO ₂ →Na ₂ SiO ₃ +CO ₂ (Formula 1)

The invention provides a method for removing CO ₂ in power plant flue gas by utilizing rice husk gasification coupled with Na ₂ SiO ₃ , comprising:

The synthetic raw material A is crushed by the conveyor 1 and the pulverizer 2 and then sent to the rice husk gasification coupling Na ₂ SiO ₃ preparation furnace 4, and oxygen C is introduced into the furnace, and the crushed synthetic raw material B is in the rice husk gasification coupling. Gasification is carried out in Na ₂ SiO ₃ preparation furnace 4 to generate combustible gas E (mainly including CO, CH ₄ and H ₂ ) and SiO ₂ (formula 2-7):

CH _x O _y →n ₁ C+n ₂ H ₂ +n ₃ H ₂ O+n ₄ CO+n ₅ CO ₂ +n ₆ CH ₄ (Formula 2)

C+O ₂ →CO ₂ (Formula 3)

2C+O ₂ →2CO (Formula 4)

C+CO ₂ →2CO (Formula 5)

C+H ₂ O→H ₂ +CO (Formula 6)

CO+3H ₂ →H ₂ O+CH ₄ (Formula 7)

Add Na ₂ CO ₃ solution D to the furnace to react with SiO ₂ to produce Na ₂ SiO ₃ absorbent H; the combustible gas is synthesized by the first heat exchanger 5 after heat exchange; the air G is input through the booster pump 3 as a pneumatic The conveyed medium, the generated powdery Na ₂ SiO ₃ is sent to the charger 6, and the powder charged treatment is performed in the charger 6 to form a charged Na ₂ SiO ₃ Absorber 1 and then enter the electric field-assisted fluidized reactor 7 middle; the flue gas J from the outlet flue of the precipitator passes through three-stage heat exchange (enters the system from the fourth heat exchanger 12, and passes through the first heat exchanger 5 and the second heat exchanger 8 for three-stage heat exchange), and then passes through the electric field. The bottom end of auxiliary fluidized reactor 7 is input, and reacts with charged Na ₂ SiO ₃ to remove CO ₂ in the flue gas (Formula 8);

Na ₂ SiO ₃ +CO ₂ →Na ₂ CO ₃ +SiO ₂ (Formula 8)

The flue gas after CO ₂ removal and the reacted absorbent K (containing Na ₂ CO ₃ , Na ₂ SiO ₃ and SiO ₂ , etc.) are transported to a two-stage cyclone for gas-solid separation; A part of the absorbent M is sent to the electric field-assisted fluidized reactor 7 (Na ₂ SiO ₃ is recycled), and another part of the absorbent N after gas-solid separation is sent to the dissolver 13 (Na ₂ CO ₃ is recycled); The water O from the condenser outlet is supplemented in the dissolver 13, the circulating absorbent and the supplemented Na ₂ CO ₃ powder P are stirred and dissolved in the water-filled dissolver 13, and the mixed system is transported to the filter 14, where the The filter 14 performs solid-liquid separation, and the filtrate (mainly Na ₂ CO ₃ solution D) is sent to the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace 4 for recycling. On the one hand, Na ₂ CO ₃ reacts with SiO ₂ in rice husk ash to generate Na ₂ SiO ₃ powder to supplement the consumed absorbent; on the other hand, the CO ₂ produced by the reaction can be used as an oxidant for rice husk gasification to generate synthetic gas. The filter residue Q (mainly containing SiO ₂ ) is directly discharged for the production of building materials; after the CO ₂ is removed after gas-solid separation and heat exchange, the flue gas L enters the chimney and is discharged directly.

The electric field-assisted fluidized reactor 7 is provided with a second heat exchanger 8 inside. The heat-absorbing medium in the second heat exchanger 8 comes from the flue gas at the outlet of the dust collector after heat exchange by the third-stage heat exchanger. Fluidized Reactor 7.

The electric field-assisted fluidized reactor 7 is equipped with a two-stage cyclone separator, which is used to improve the gas-solid separation efficiency and reduce the number of solid particles in the flue gas; For charging the Na ₂ SiO ₃ powder; the electric field-assisted fluidization reactor 7 is provided with an electrode plate, and an electric field is formed in the bed, so that the Na ₂ SiO ₃ powder can be smoothly fluidized under the action of the flue gas flow. .

The upper part of the dissolver 13 is charged with water and Na ₂ CO ₃ powder, and the water comes from the outlet of the condenser of the power plant boiler. The filtrate (mainly containing Na ₂ CO ₃ ) of the filter 14 is sent to the rice husk gasification coupled Na ₂ SiO ₃ preparation furnace 4. On the one hand, Na ₂ CO ₃ in the filtrate reacts with SiO ₂ in the rice husk ash to generate Na ₂ SiO ₃ supplements the consumed absorbent. On the other hand, the CO ₂ generated during the synthesis of Na ₂ SiO ₃ absorbent can be used as an oxidant for rice husk gasification to produce synthetic gas.

The temperature of the reaction of rice husks and Na ₂ CO ₃ solution in the furnace to synthesize Na ₂ SiO ₃ is 900 °C, and the heat of the reaction is provided by the gasification of rice husks. The reaction temperature of the synthesized Na ₂ SiO ₃ absorbent to remove CO ₂ is 700°C, and the heat of the reaction is obtained from the flue gas of the coal-fired power station and the absorbent circulated after the reaction, the synthetic gas and the electric field-assisted fluidized reactor. 7 heat exchange provided.

The synthesis principle of the Na ₂ SiO ₃ absorbent in the rice husk gasification coupled Na 2 SiO 3 preparation furnace 4 is that the silicon salt precursor in the rice husk reacts with the injected Na ₂ CO ₃ solution at high temperature to obtain Na ₂ SiO ₃ and CO ₂ .

The charging device 6 adopts the principle of a tube-type electrostatic device, and an insulating tape is arranged inside to avoid the neutralization of charged particles, and the electric energy required by the charging device 6 is provided by the power plant.

The electric field-assisted fluidized reactor 7 is provided with an insulating tape inside to avoid electric neutralization, and the electric energy required by the reactor is provided inside the power plant.

The process of CO ₂ adsorption on the surface of Na ₂ SiO ₃ absorbent is an exothermic chemical reaction, and the reaction temperature is about 700 °C. In the actual _CO2 removal process, the reaction exotherm makes the interior of the bed warm up and gradually deviates from the optimal reaction temperature range, resulting in a decrease in the decarburization efficiency _{of Na2SiO3} . The electric field-assisted fluidized reactor 7 is provided with a second heat exchanger 8, and the flue gas at the outlet of the dust collector after heat exchange by the three-stage heat exchanger is used as a cooling medium, and the bed is cooled by absorbing heat through the flue gas. Maintain the decarburization temperature within the optimal reaction temperature range (about 700°C) to improve the decarburization efficiency of Na ₂ SiO ₃ .

As described above, the device and method provided by the embodiments of the present invention can effectively capture CO ₂ in flue gas by activating rice husks and introducing Na ₂ CO ₃ solution for modification, followed by charging treatment to synthesize Na ₂ SiO ₃ absorbent. ; The reaction of CO ₂ produced in the process of absorbent synthesis with rice husk pyrolysis products can produce high-quality gas; Na ₂ CO ₃ generated by the reaction of Na ₂ SiO ₃ absorbent with CO ₂ can be recycled to be used in absorbent synthesis. Silicon-rich aluminum materials can be used in the building materials industry.

Claims (8)

1. The utility model provides a system for rice husk gasification coupling sodium silicate entrapment power plant's flue gas carbon dioxide which characterized in that includes: gasification coupling of rice husk with Na₂SiO₃The device comprises a preparation furnace, a charging device, an electric field auxiliary type fluidized reactor, a material separation device, a dissolver, a filter and a heat exchanger; wherein,

the rice hull gasification coupling Na₂SiO₃The input end of the preparation furnace is synthetic raw material O₂And Na₂CO₃The solution inlet and the solution outlet are connected with a charging device and a first heat exchanger;

the output end of the charge device is connected with the electric field auxiliary type fluidized reactor;

the electric field auxiliary type fluidized reactor is internally provided with a second heat exchanger, and the output end of the electric field auxiliary type fluidized reactor is connected with the material separation device;

the material separation device is a two-stage cyclone separator, the output end of the upper part of the first-stage cyclone separator is connected with a second-stage cyclone separator, the output end of the upper part of the second-stage cyclone separator is connected with a third heat exchanger, the output ends of the lower parts of the two-stage cyclone separators are connected back to the electric field auxiliary fluidized reactor, and a pipeline is additionally arranged at the output end of the lower part of the two-stage cyclone separator and is connected with a dissolver through a fourth heat exchanger;

the output end of the dissolver is connected with the filter;

the filtrate output end of the filter is connected to the rice hull gasification coupling Na₂SiO₃A preparation furnace;

and the fourth heat exchanger is additionally provided with a pipeline connected to the first heat exchanger, the first heat exchanger is additionally provided with a pipeline connected to the second heat exchanger, and the second heat exchanger is additionally provided with a pipeline connected back to the bottom end of the electric field auxiliary type fluidized reactor.

2. The system for trapping carbon dioxide in flue gas of power plant by rice husk gasification coupled sodium silicate according to claim 1, wherein the rice husk gasification is coupled with Na₂SiO₃The preparation furnace is of two-section type, the upper input end is provided with a nozzle and is used for synthesizing raw materials and O₂The lower input end of the inlet is provided with a sprayer which is Na₂CO₃And (4) an inlet of the solution.

3. The system for capturing the carbon dioxide in the flue gas of the power plant by the rice husk gasification coupling sodium silicate as claimed in claim 1, wherein the electric charger and the electric field assisted fluidized reactor are internally provided with insulating belts, and the required electric energy is provided from the interior of the power plant.

4. A method for capturing carbon dioxide in flue gas of a power plant by coupling rice husk gasification and sodium silicate based on the system of any one of claims 1-3, comprising the following steps:

step 1), crushing synthetic raw materials, and then feeding the crushed synthetic raw materials into the rice hull gasification coupling Na₂SiO₃In the preparation furnace, O is introduced into the furnace₂To proceed withGasifying while adding Na₂CO₃Solution, synthesis of Na after reaction₂SiO₃An absorbent and a combustible gas;

step 2) Na₂SiO₃The absorbent enters a charging device, and powder is charged in the charging device to form charged Na₂SiO₃The absorbent enters the electric field auxiliary fluidized reactor; the combustible gas is subjected to heat exchange through a first heat exchanger to synthesize fuel gas;

and 3) flue gas from an outlet flue of a dust remover of the power plant enters the system through a fourth heat exchanger, is subjected to three-stage heat exchange through a first heat exchanger and a second heat exchanger, is input from the bottom end of the electric field auxiliary type fluidized reactor, and is mixed with charged Na₂SiO₃Absorbent reaction to remove CO in flue gas₂；

Step 4) CO removal₂The flue gas and the reacted absorbent enter the two-stage cyclone separator together for gas-solid separation, a part of the separated absorbent is conveyed back to the electric field auxiliary fluidized reactor through the output end at the lower part of the two-stage cyclone separator, and unreacted Na is recycled₂SiO₃The other part is subjected to heat exchange by a fourth heat exchanger and then is conveyed to a dissolver; CO is removed from the separated flue gas₂The heat exchange can be carried out through the third heat exchanger, and then the waste heat enters a chimney to be directly discharged;

step 5) supplementing water and Na from the outlet of the condenser to the dissolver₂CO₃Powder, heat-exchanged Na₂SiO₃Stirring the absorbent uniformly, conveying the formed mixed system to a filter for solid-liquid separation, and returning the filtrate to the rice hull gasification coupling Na₂SiO₃The preparation furnace is recycled, and the discharged filter residue rich in silicon and aluminum can be directly discharged and collected for the building material industry.

5. The method for capturing the carbon dioxide in the flue gas of the power plant by the coupling of rice husk gasification and sodium silicate as claimed in claim 4, wherein the gasification process in step 1) comprises four stages of drying, pyrolysis, oxidation and reduction, wherein the drying temperature is 50-100 ℃, the pyrolysis temperature is 150-300 ℃, the oxidation temperature is 300-1200 ℃ and the reduction temperature is 600-900 ℃.

6. The method for capturing the flue gas carbon dioxide of the power plant by the rice husk gasification coupling sodium silicate according to claim 4, wherein the synthetic raw material in the step 1) is rice husk or wheat stem leaves.

7. The method for capturing the carbon dioxide in the flue gas of the power plant by coupling rice husk gasification and sodium silicate according to claim 4, wherein the step 1) is to synthesize Na₂SiO₃The reaction temperature of (2) was 900 ℃.

8. The method for capturing the carbon dioxide in the flue gas of the power plant by the rice husk gasification coupled sodium silicate according to claim 4, wherein the CO is removed in the step 3)₂The reaction temperature of (2) was 700 ℃.

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