Water coal slurry gasification chemical chain combustion device and combustion method

Abstract

The application discloses a kind of water coal slurry gasification chemical chain combustion device and combustion method, including gasification reactor, fuel reactor and air reactor of sleeve in fuel reactor outside in gasification reactor outside, wherein, the bottom of fuel reactor is provided with quenching chamber, quenching chamber is used to fill quenching liquid in, and the body portion of fuel reactor is separated by air distribution plate;The bottom outlet of gasification reactor is connected with quenching tube, and the bottom of quenching tube is inserted into quenching chamber;The top of gasification reactor is connected with water coal slurry source and gasification agent source respectively;The bottom of fuel reactor is connected with air reactor by returning material device, for transporting oxygen carrier after reduction into air reactor;The top of air reactor is connected with fuel reactor by cyclone separator, for returning oxygen carrier after oxidation to fuel reactor.Effective prevention is polluted to oxygen carrier after fuel combustion, the device effectively avoids the pollution of molten slag to oxygen carrier after fuel combustion, thereby prolongs the service life of oxygen carrier, realizes the multiple cyclic utilization of oxygen carrier.Can significantly reduce the circulation amount of oxygen carrier, and then effectively reduce investment and operating cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical looping combustion, in particular to a water-coal slurry gasification chemical looping combustion device and combustion method. BACKGROUND

[0002] The statements herein are provided only to enhance understanding of the present application and are not necessarily intended to constitute the prior art.

[0003] With the growing global demand for energy and the increasing environmental problems, the demand for efficient and clean energy has become increasingly urgent. Although traditional combustion technology meets this demand to some extent, it has problems such as energy loss and harmful gas emission. In order to overcome these limitations, chemical looping combustion technology has emerged. This technology is characterized by a new type of combustion method with CO2 internal separation characteristics, which can achieve CO2 separation without additional energy. The chemical looping combustion system separates the traditional fuel and combustion control into two gas-solid reactions through the circulation of the oxygen carrier between two reactors. The fuel does not need to contact with air, and the oxygen in the air is transferred to the fuel by the oxygen carrier. Effective separation of N2 and CO2 is achieved, avoiding additional energy consumption of CO2. At the same time, the system can also realize the cascade utilization of energy, improving the energy utilization efficiency of the whole system. Therefore, the application of chemical looping combustion technology in fuel conversion process has extremely important significance for reducing China's CO2 emissions and realizing economic, efficient and clean utilization of fuel.

[0004] In the chemical looping combustion system, the selection of oxygen carrier and the design of reactor structure play a crucial role in the whole combustion process. Among them, the design of reactor structure puts forward a series of key requirements for the reactor design and operation of chemical looping combustion technology, including comprehensive consideration of reactor structure, material and operating conditions. The reactor design must ensure efficient heat and mass transfer process. By selecting appropriate reactor structure, energy and mass transfer can be effectively achieved in each step of the whole reaction chain. The series fluidized bed reactor system is widely used in chemical looping combustion due to its excellent heat and mass transfer characteristics.

[0005] Currently, the traditional solid fuel direct chemical looping combustion process has the following problems: 1) when the oxygen carrier directly contacts with the coal, the coal ash may have a significant impact on the oxygen carrier. The ash may cover the active surface of the oxygen carrier, cause the blockage of the oxygen carrier surface pores, reduce the lattice oxygen transfer efficiency, and further have a negative impact on the reactor performance. Certain ash components may cause corrosion to the oxygen carrier material, ultimately leading to a reduction in the service life of the oxygen carrier. In addition, the ash will adhere to the surface of the oxygen carrier, affecting the fluidization performance of the oxygen carrier. 2) The oxygen carrier circulation amount is large, and the heat of the traditional fuel reactor is entirely carried by the oxygen carrier from the air reactor. In order to maintain the temperature of the fuel reactor, the circulation amount of the oxygen carrier between the air reactor and the fuel reactor is very high. The high circulation amount of the oxygen carrier requires a large amount of power consumption, and thus the operation and investment costs are high. 3) Considering the temperature resistance characteristics of the oxygen carrier and the ash melting characteristics, the temperature of the traditional fuel reactor cannot be too high, and is controlled at about 950 DEG C. Under this temperature condition, the unconverted carbon content in the coal powder at the outlet of the reactor is high, leading to a low carbon conversion rate of the coal and affecting the energy conversion efficiency. SUMMARY

[0006] In view of the problems existing in the prior art, the purpose of the present application is to provide a coal water slurry gasification chemical looping combustion device and combustion method, which effectively prevents the pollution of the oxygen carrier by the molten slag after fuel combustion, effectively avoids the pollution of the oxygen carrier by the molten slag generated after fuel combustion, thereby prolonging the service life of the oxygen carrier and realizing the multiple recycling of the oxygen carrier. At the same time, the fuel reactor of the present application is sandwiched between the gasification reactor and the air reactor to form a nested structure, and through the heat exchange of the partition wall type, the high-temperature gasification reactor and air reactor can provide part of the heat for the fuel reactor, which can significantly reduce the circulation amount of the oxygen carrier, thereby effectively reducing the investment and operation costs. In addition, in the present application, the coal water slurry gasification process is not affected by the oxygen carrier, so that the high temperature reaches 1300-1500 DEG C, thereby significantly improving the carbon conversion rate.

[0007] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0008] In the first aspect, the present application provides a coal water slurry gasification chemical looping combustion device, comprising a gasification reactor, a fuel reactor sleeved on the outside of the gasification reactor, and an air reactor sleeved on the outside of the fuel reactor, wherein,

[0009] The bottom of the fuel reactor is provided with a quenching chamber, the quenching chamber is used for containing quenching liquid, and the quenching chamber and the body part of the fuel reactor are separated by a wind distribution plate;

[0010] The bottom outlet of the gasification reactor is connected with a quenching pipe, the bottom of the quenching pipe is inserted into the quenching chamber, and the top of the gasification reactor is connected with a coal water slurry source and a gasification agent source respectively;

[0011] The bottom of the fuel reactor is connected with the air reactor through a return feeder for transporting the reduced oxygen carrier into the air reactor;

[0012] The top of the air reactor is connected with the fuel reactor through a cyclone separator for returning the oxidized oxygen carrier into the fuel reactor.

[0013] The fuel reactor is sandwiched between the gasification reactor and the air reactor to form a nested structure, and through the heat exchange between the intermediate wall, the high-temperature gasification reactor and the air reactor can provide part of the heat for the fuel reactor, while significantly reducing the circulation amount of the oxygen carrier, thereby effectively reducing the investment and operation cost.

[0014] The mixture of the crude synthesis gas and the molten slag enters the quenching device, and the molten slag is separated out (the molten slag is discharged through a slag discharge port), and the pure synthesis gas is obtained, and then is introduced into the fuel reactor through a wind distribution plate, so as to prevent the molten slag from contaminating the oxygen carrier and facilitate the recycling of the oxygen carrier.

[0015] The wind distribution plate can prevent the oxygen carrier from falling into the quenching device, and the oxygen carrier is subjected to the oxidation-reduction reaction with CO and H2, and the oxygen carrier is reduced to Me x O y-1 by CO and H2, and CO and H2 are oxidized to CO2 and water vapor by the oxygen carrier, and the generated CO2 and water vapor escape from the gas outlet at the upper part of the fuel reactor, and the water vapor is condensed to obtain pure CO2.

[0016] In some embodiments, the body of the gasification reactor is completely located inside the fuel reactor, and the feeding port of the gasification reactor extends outward from the gasification reactor. The water coal slurry and the gasification agent are subjected to the gasification reaction in the gasification reactor to generate the crude synthesis gas and the molten slag. Since the gasification reaction is an exothermic reaction, a large amount of heat is generated. By completely placing the gasification reactor inside the fuel reactor and heating the fuel reaction chamber through the intermediate wall heating mode, the loss and waste of heat in the gasification reactor can be effectively avoided.

[0017] In some embodiments, the bottom of the gasification reactor is in the shape of a funnel, and the quenching pipe is connected to the lowest part of the funnel. Since a large amount of molten slag is generated in the gasification reaction process of the water coal slurry, the bottom of the gasification reactor is arranged in the shape of a funnel, so that the generated molten slag can be effectively discharged, and the discharge dead angle of the molten slag is avoided.

[0018] Preferably, the outlet end of the quenching pipe is a flared mouth.

[0019] In some embodiments, the gasification reactor is a straight cylindrical steel pressure-resistant container, and the inner wall is provided with a refractory layer. The arrangement of the refractory layer can effectively prevent the erosion of the molten slag and the crude coal gas to the gasification reactor.

[0020] In some embodiments, the air distribution plate is obliquely arranged between the quenching pipe and the inner wall of the fuel reactor, and is arranged downwardly along the direction from the quenching pipe to the fuel reactor.

[0021] The air distribution plate is arranged above the oxygen carrier, and the air distribution plate is obliquely arranged, which is beneficial to the oxygen carrier after reacting with the synthesis gas to return to the air reactor through the return feeder.

[0022] In addition, the air distribution plate is obliquely arranged, which can reduce the amount of quenching liquid carried by the synthesis gas flowing through the quenching liquid, on the one hand, to avoid waste of the quenching liquid, and on the other hand, to reduce the adverse effects of the entrained quenching liquid on the subsequent reaction.

[0023] In some embodiments, the side of the air reactor provided with the cyclone separator and the opposite side thereof are connected with the fuel reactor through return feeders, the return feeders and the air reactor are connected through legs, and the ends of the legs are used to be connected with an air source to provide power for the returned oxygen carrier by using compressed air.

[0024] Preferably, the bottom of the air reactor is flat, and the air reactor is obliquely arranged as a whole, and the end of the air reactor provided with the cyclone separator is located at the lowest end.

[0025] The bottom of the air reactor is obliquely arranged, the reduced oxygen carrier after reacting with air is collected at the side provided with the cyclone separator, and the collected oxygen carrier enters the cyclone separator under the blowing of the compressed air, so that the oxidized oxygen carrier is conveniently recycled to the fuel burner.

[0026] In some embodiments, the lowest end of the quenching chamber is provided with a slag discharge port, and the sidewall of the quenching chamber is provided with a liquid injection port.

[0027] Because a large amount of molten slag is generated in the coal water slurry gasification process, the molten slag collected in the quenching chamber can be discharged through the slag discharge port, and the amount of quenching liquid in the quenching chamber can be supplemented by the liquid injection port when the amount of quenching liquid is insufficient.

[0028] In some embodiments, the parts of the fuel reactor and the air reactor in contact with the environment are provided with a heat insulation layer to prevent waste of heat of the reaction system.

[0029] In a second aspect, the present application provides a coal water slurry gasification chemical looping combustion method, comprising the following steps:

[0030] The coal water slurry and oxygen are introduced into the gasification reactor to perform a gasification reaction, the reaction temperature is 1300-1500℃, and the reaction pressure is 3-6.5 MPa.

[0031] The crude synthesis gas and molten slag generated by the gasification reaction of the coal water slurry enter a quenching chamber, the molten slag is separated, and the obtained pure synthesis gas enters a fuel combustor to react with an oxygen carrier, the synthesis gas is reacted to generate CO2 and water vapor, and the oxygen carrier is reduced;

[0032] The reduced oxygen carrier enters an air reactor through a return feeder to react with air, and the oxidized oxygen carrier is transported by airflow to a cyclone separator, and the separated oxygen carrier returns to the fuel reactor.

[0033] In the gasification reactor, the reaction temperature can reach 1300-1500℃ without the participation of the oxygen carrier, which not only improves the gasification degree of the coal water slurry, but also keeps the molten slag in a molten state, facilitating the collection and separation of the molten slag (the ash melting point of the molten slag is below 1300℃, so as to ensure that the ash and slag are in a molten state during the gasification process, facilitating liquid slag discharge).

[0034] In some embodiments, the reaction temperature in the fuel combustor is 900-950℃.

[0035] In some embodiments, the oxygen carrier is selected from one or a combination of Cu-based oxygen carriers, Fe-based oxygen carriers, Mn-based oxygen carriers, Ni-based oxygen carriers, Co-based oxygen carriers, calcium sulfate, or silicon oxide.

[0036] The beneficial effects achieved by one or more embodiments of the present application are as follows:

[0037] 1. Significantly improve carbon conversion rate: compared with the traditional solid fuel gasification method, the gasification process of the present application is carried out at high temperature (1300-1500℃), and the gasification process is not affected by the oxygen carrier, the carbon conversion rate and conversion efficiency are significantly improved, and this technical breakthrough makes the gasification of solid fuel more efficient.

[0038] 2. Significantly reduce the circulation amount of the oxygen carrier: through innovative design, the fuel reactor of the present application is sandwiched between the gasification reactor and the air reactor to form a nested structure, and through the heat exchange of the partition wall, the high-temperature gasification reactor and air reactor can provide part of the heat for the fuel reactor, which can significantly reduce the circulation amount of the oxygen carrier, thereby effectively reducing the investment and operating cost.

[0039] 3. Significantly prolonging the service life of oxygen carriers: In traditional solid fuel gasification processes, a common problem is that oxygen carriers are easily affected by coal ash, leading to adverse conditions such as blockage, covering, and corrosion. Unlike this, the present application uses coal water slurry as raw material for gasification and chemical looping combustion. Coal water slurry is a composite fuel composed of 65% coal, 34% water, and 1% chemical additives. After careful process processing, it has the advantages of high calorific value, low ash content, easy ignition, and convenient slagging. In a specific coal water slurry gasification process, the non-gasifiable ash and molten slag are separated by a quenching device to ensure that the oxygen carriers are not contaminated. This not only significantly prolongs the service life of the oxygen carriers and effectively controls the emission of pollutants, but also the waste ash can be comprehensively utilized.

[0040] In summary, the present application presents significant innovation and practicality in the field of coal water slurry gasification chemical looping combustion, providing a feasible and sustainable solution for the efficient use of solid fuels. BRIEF DESCRIPTION OF DRAWINGS

[0041] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The embodiments of these drawings are set forth to explain the present application and are not intended to limit the present application unduly.

[0042] Figure 1 is a structural schematic diagram of a coal water slurry gasification chemical looping combustion device according to an embodiment of the present application.

[0043] In the figure, 1 is a feeder, 2 is a gasification reactor, 3 is a heat insulation layer, 4 is an air reactor, 5 is a fuel reactor, 6 is a second feed leg, 7 is a wind distribution plate, 8 is a quenching chamber, 9 is a second return feeder, 10 is a first return feeder, 11 is a first feed leg, 12 is a quenching pipe, 13 is a refractory material layer, 14 is a third return feeder, and 15 is a cyclone separator. DETAILED DESCRIPTION

[0044] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0045] The present application will be further described below in conjunction with the embodiments.

[0046] Reference Figure 1As shown in the figure, a water coal slurry gasification chemical chain combustion device mainly comprises a gasification reactor 2, a fuel reactor 5, an air reactor 4 and a quenching device 8, the fuel reactor 5 is sandwiched between the gasification reactor 2 and the air reactor 4 to form a nested structure, and through the heat exchange of the intermediate wall, the high-temperature gasification reactor 2 and the air reactor 4 can provide part of the heat for the fuel reactor 5, while the circulation amount of the oxygen carrier is significantly reduced, and the investment and operation cost are effectively reduced.

[0047] The outer wall of the reactor exposed to the environment is provided with a heat insulation layer 3 to prevent heat loss of the system; the gasification reactor 2 is a vertical cylindrical steel pressure-resistant container, and the inner wall is lined with a high-quality refractory material layer 13 to prevent erosion of molten slag and raw coal gas.

[0048] As shown in the figure, a water coal slurry gasification chemical chain combustion method comprises the following steps: Figure 1

[0049] The water coal slurry and the gasification agent (oxygen) enter the gasification reactor 2 through the inlet C in the feeder 1, the temperature of the gasification reactor 2 is controlled at 1300-1500℃, and the pressure is controlled at 3-6.5 MPa; in the oxygen atmosphere, the water coal slurry undergoes a gasification reaction to generate raw synthetic gas and molten slag, wherein the main components of the raw synthetic gas are CO and H2.

[0050] The mixture of the raw synthetic gas and the molten slag enters the quenching device 8, the molten slag is separated out (the molten slag is discharged through the slag discharge port G), and pure synthetic gas is obtained; the pure synthetic gas enters the fuel reactor 5 through the air distribution plate 7, the temperature of the fuel reactor 5 is controlled at 900-950℃, and the pressure is controlled at 1-3.5 MPa; the active oxygen carrier (Me x O y ) is added to the top of the fuel reactor 5 through the feeding port D, the air distribution plate 7 can prevent the oxygen carrier from falling into the quenching device 8, the oxygen carrier undergoes an oxidation-reduction reaction with CO and H2, the oxygen carrier is reduced to Me x O y-1 by CO and H2, and CO and H2 are oxidized to CO2 and water vapor by the oxygen carrier, and the main reaction is:

[0051] Me x O y + CO = Me x O y-1 + CO2;

[0052] Me x O y + H2 = Me x O y-1 + H2O.

[0053] ​The generated CO2 and water vapor escape from the gas outlet O of the upper part of the fuel reactor 5, the water vapor is condensed, and pure CO2 is obtained; the reduced oxygen carrier enters the air reactor 4 through the first return feeder 9 and the second return feeder 10, the temperature of the air reactor 4 is controlled at 950-1000℃, and the pressure is controlled at 3-5.5 MPa; air is introduced into the air reactor 4 and the bottom A and E of the leg thereof, and Me x O y-1 is oxidized by air into an oxygen carrier, and the air is converted into lean air; the main reaction is:

[0054] Me x O y-1 +1 / 2O2=Me x O y .

[0055] Then, the lean air is discharged from the lean air outlet I of the upper part of the cyclone separator 15, and the oxygen carrier is returned to the fuel reactor 5 through the third return feeder 14, so as to realize the circulation of the oxygen carrier.

[0056] The gasification reactor 2 separates the molten slag after gasifying the coal water slurry through the quenching device 8, obtains pure synthesis gas, and then introduces the synthesis gas into the fuel reactor through the air distribution plate 7, so as to prevent the molten slag from contaminating the oxygen carrier and facilitate the recycling of the oxygen carrier.

[0057] The ash melting point of the molten slag is below 1300℃, and the temperature of the gasification reaction is controlled at above 1300℃, so as to ensure that the ash slag is in a molten state during the gasification process, and facilitate the liquid slag discharge. The active oxygen carrier is a metal oxygen carrier or a non-metal oxygen carrier; the metal oxygen carrier or the non-metal oxygen carrier is one or a mixture of several of the following oxygen carriers: Cu-based oxygen carrier, Fe-based oxygen carrier, Mn-based oxygen carrier, Ni-based oxygen carrier, Co-based oxygen carrier, calcium sulfate, silicon oxide, etc.

[0058] Examples:

[0059] Illinois coal is used as a raw material for preparing coal water slurry (a pipeline transportable mixed fluid fuel containing 65% of coal, 34% of water and 1% of additives, % is mass percent), a certain concentration of coal is prepared by using a wet rod or ball milling method, and NiO is used as an oxygen carrier in the application, wherein the industrial analysis and elemental analysis data of the coal are shown in Table 1.

[0060] Table 1 Industrial analysis and elemental analysis of Illinois coal

[0061]

[0062] The temperature of the gasification reactor 2 is controlled at 1500 DEG C, the pressure is controlled at 6.5 MPa, the temperature of the fuel reactor 5 is controlled at 950 DEG C, the pressure is controlled at 3.5 MPa, the temperature of the air reactor 4 is controlled at 950 DEG C to 1000 DEG C, and the pressure is controlled at 5.5 MPa, so that the NiO is recycled, and the energy utilization efficiency of the system is improved. The carbon conversion rate of the traditional fuel reactor is usually between 50% and 85%. In comparison, according to the carbon conversion rate formula (i.e. the ratio of the carbon content in the fuel reactor outlet gas to the carbon content in the carbon-based fuel entering the device), the carbon conversion rate of the coal water slurry in the present application is more than 99%. At the same time, the oxygen carrier circulation amount required by the fuel reactor of the coal water slurry chemical looping combustion system can reach only one third of that of the traditional fuel reactor. In addition, the influence of the ash in the coal on the oxygen carrier life is almost negligible.

[0063] The preferred embodiments of the present application have been described above with the aid of drawings, but the present application covers any modifications and variations of the present application that fall within the scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the present application.

Claims

1. A coal-water slurry gasification chemical looping combustion device, characterized in that: It includes a gasification reactor, a fuel reactor fitted outside the gasification reactor, and an air reactor fitted outside the fuel reactor, wherein, The bottom of the fuel reactor is equipped with a quenching chamber, which is used to hold quenching liquid. The quenching chamber is separated from the main body of the fuel reactor by an air distribution plate. The bottom outlet of the gasification reactor is connected to a quenching pipe, and the bottom of the quenching pipe is inserted into the quenching chamber; the top of the gasification reactor is connected to the coal-water slurry source and the gasifying agent source respectively. The bottom of the fuel reactor is connected to the air reactor via a return feeder, which is used to transport the reduced oxygen carrier to the air reactor; The top of the air reactor is connected to the fuel reactor via a cyclone separator to return the oxidized oxygen carrier to the fuel reactor.

2. The water-coal slurry gasification chemical looping combustion device according to claim 1, characterized in that: The gasification reactor is located entirely inside the fuel reactor, with its feed inlet extending outward from the gasification reactor. The bottom of the gasification reactor is funnel-shaped, and the quenching tube is connected to the lowest point of the funnel. The outlet end of the quenching tube is a flared shape.

3. The water-coal slurry gasification chemical looping combustion device according to claim 1, characterized in that: The gasification reactor is a vertical cylindrical steel pressure vessel with a refractory layer on its inner wall.

4. The water-coal slurry gasification chemical looping combustion device according to claim 1, characterized in that: The air distribution plate is inclined between the quenching pipe and the inner wall of the fuel reactor, and is inclined downward in the direction from the quenching pipe to the fuel reactor.

5. The water-coal slurry gasification chemical looping combustion device according to claim 1, characterized in that: The air reactor is connected to the fuel reactor via a return feeder on the side with the cyclone separator and the opposite side. The return feeder and the air reactor are connected via a feed leg, the end of which is used to connect to an air source to provide power for the returned oxygen carrier using compressed air. The bottom of the air reactor is flat and the whole is inclined, with the end where the cyclone separator is located at the lowest point.

6. The water-coal slurry gasification chemical looping combustion device according to claim 1, characterized in that: The lowest end of the quenching chamber is provided with a slag discharge port, and the side wall of the quenching chamber is provided with a liquid injection port.

7. The water-coal slurry gasification chemical looping combustion device according to claim 1, characterized in that: The portions of the fuel reactor and air reactor that are in contact with the environment are equipped with insulation layers.

8. A method for chemical looping combustion of coal-water slurry using the coal-water slurry gasification chemical looping combustion apparatus according to any one of claims 1-7, characterized in that: Includes the following steps: Water-coal slurry and oxygen are introduced into a gasification reactor for gasification reaction at a temperature of 1300~1500℃ and a pressure of 3~6.5MPa. The crude syngas and slag produced by the gasification reaction of coal-water slurry enter the quenching chamber, where the slag is separated and the pure syngas obtained enters the fuel burner to react with the oxygen carrier. The syngas reacts to produce CO2 and water vapor, and the oxygen carrier is reduced. The reduced oxygen carrier enters the air reactor via the return feeder, where it reacts with air. The oxidized oxygen carrier is then transported by airflow to the cyclone separator, and the separated oxygen carrier is returned to the fuel reactor.

9. The method for chemical looping combustion of coal-water slurry gasification according to claim 8, characterized in that: The reaction temperature in the fuel burner is 900~950℃.

10. The method for chemical looping combustion of coal-water slurry gasification according to claim 8, characterized in that: The oxygen carrier is selected from one or a combination of Cu-based oxygen carriers, Fe-based oxygen carriers, Mn-based oxygen carriers, Ni-based oxygen carriers, Co-based oxygen carriers, calcium sulfate, or silicon oxide.

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