A near zero carbon emission photo-coal complementary methane production system

Abstract

This disclosure provides a near-zero carbon emission solar-coal complementary methane production system, comprising a coal gasification unit, a hydrogen production unit, and a methanation unit. The coal gasification unit is used to gasify raw coal to produce carbon monoxide. The hydrogen production unit is used to electrolyze the condensate produced during the coal gasification process to produce hydrogen. The methanation unit is used to react the hydrogen produced by the hydrogen production unit with the carbon monoxide produced by the coal gasification unit to produce methane. This system reduces energy consumption and water usage, while minimizing environmental impact, thus achieving clean, efficient, and sustainable coal energy conversion.

Description

Technical Field

[0001] At least one embodiment of this disclosure relates to the fields of pyrolysis and gasification, and methane production technology, and more particularly to a near-zero carbon emission photovoltaic-coal complementary methane production system. Background Technology

[0002] Coal is a vital energy source, accounting for more than half of global energy consumption. In recent years, with the continuous optimization of the coal energy conversion industry, the industry scale has been expanding, technological iteration has been accelerating, and modern coal conversion technologies have been widely applied and developed.

[0003] However, current coal energy conversion production practices still face some challenges: First, the energy consumption in the production process is relatively high, affecting overall energy efficiency; second, the consumption of water resources is large, putting pressure on the sustainable use of water resources; and third, a large amount of human, material and financial resources are needed to control pollutant emissions. Summary of the Invention

[0004] To address at least one of the aforementioned technical problems, this disclosure provides a near-zero carbon emission solar-coal complementary methane production system that can reduce energy consumption and water usage while minimizing environmental impact, thereby achieving clean, efficient, and sustainable development of coal energy conversion.

[0005] As one aspect of this disclosure, a near-zero carbon emission photovoltaic-coal complementary methane production system is provided, comprising a coal gasification unit, a hydrogen production unit, and a methanation unit. The coal gasification unit is suitable for gasifying raw coal to produce carbon monoxide. The hydrogen production unit is suitable for electrolyzing the condensate generated during the coal gasification process to produce hydrogen. The methanation unit is suitable for reacting the hydrogen produced by the hydrogen production unit with the carbon monoxide produced by the coal gasification unit to produce methane.

[0006] According to embodiments of this disclosure, the coal gasification assembly includes a pyrolysis furnace, a burner, a condenser, and a gasifier. The pyrolysis furnace is suitable for pyrolyzing the raw coal to produce char and pyrolysis oil / gas. The burner is suitable for burning the pyrolysis oil / gas with the aid of oxygen generated during the electrolysis process to obtain flue gas. The condenser is suitable for condensing the flue gas, separating the condensate and carbon dioxide. The gasifier is suitable for using carbon dioxide from the condenser as a gasifying agent to gasify the char from the pyrolysis furnace, producing carbon monoxide. The flue gas provides a high-temperature environment for the char gasification reaction before condensation. Furthermore, the flue gas also provides a medium-high temperature environment for the raw coal to undergo pyrolysis before condensation.

[0007] According to an embodiment of this disclosure, the gasifier includes a furnace body, an outer furnace wall, and a flue gas duct. An internal space is formed within the furnace body, and the outer furnace wall is located outside the furnace body, forming an external flue gas duct between the furnace body and the outer wall. The flue gas duct is vertically installed within the internal space, and its upper part is connected to the external flue gas duct via a pipe fitting. The burner is mounted on the furnace body and located below the flue gas duct, providing flue gas from below. The flue gas rises within the flue gas duct to heat the downward-flowing coal char and the upward-flowing carbon dioxide within the internal space, causing the coal char to undergo a gasification reaction. The cooled flue gas is discharged through the external flue gas duct and passes through the pyrolysis furnace via a conveying pipe, providing a medium-to-high temperature environment for the pyrolysis of the raw coal.

[0008] According to an embodiment of this disclosure, the furnace body further includes a feed pipe. The feed pipe passes through the outer furnace wall and is installed at the top of the furnace body to communicate with the receiving space, wherein the coke enters the receiving space via the feed pipe. The flue gas pipe is located below the feed pipe, and the top end of the flue gas pipe is constructed in a conical shape so that the coke falling at the top of the flue gas pipe is evenly dispersed within the receiving space.

[0009] According to an embodiment of this disclosure, the gasifier further includes a tubular component extending horizontally below and communicating with the flue gas duct. The tubular component penetrates both opposite sides of the furnace body to guide the flue gas into the flue gas duct. Two burners are symmetrically arranged at both ends of the tubular component along its axial direction to provide the flue gas through fuel combustion.

[0010] According to an embodiment of this disclosure, the bottom of the furnace body is provided with a discharge port, which is suitable for allowing the ash and slag generated after the coking coal undergoes the gasification reaction to be discharged. The furnace body also includes a gas distribution plate, which is obliquely installed between the periphery of the discharge port and the furnace body, so that a gas chamber adjacent to the receiving space is formed between the gas distribution plate and the bottom and side walls of the furnace body. Carbon dioxide from the condenser enters the gas chamber through an inlet located at the lower part of the gas chamber, passes through multiple through holes on the gas distribution plate into the receiving space, contacts the coking coal in the receiving space, and causes the ash and slag falling on the gas distribution plate to be discharged through the discharge port.

[0011] According to embodiments of this disclosure, the coal gasification assembly further includes a dryer suitable for drying the raw coal to obtain dried raw coal and water vapor. The dried raw coal is then transported to the pyrolysis furnace for pyrolysis, and the water vapor is transported to the hydrogen production assembly. The transport pipeline passes through the dryer after passing through the pyrolysis furnace to provide a medium-temperature environment for drying the raw coal. The other end of the transport pipeline is connected to the condenser to condense the cooled flue gas.

[0012] According to embodiments of this disclosure, the hydrogen production assembly includes an electrolyzer and a photovoltaic panel. The electrolyzer is suitable for receiving the condensate, and the photovoltaic panel is suitable for converting solar energy into electrical energy to electrolyze the condensate in the electrolyzer.

[0013] According to embodiments of this disclosure, the hydrogen production assembly further includes a water purifier adapted to filter the condensate before it enters the electrolyzer.

[0014] According to embodiments of this disclosure, the methanation assembly includes multiple cascaded reactors. These cascaded reactors are adapted to allow carbon monoxide from the gasifier and hydrogen from the hydrogen production assembly to undergo the methanation reaction in stages under the action of a catalyst. Specifically, following the flow direction of the carbon monoxide, the product gas generated by the downstream reactor is used as a recirculating gas to control the temperature of the first-stage reactor. This product gas includes the methane, unreacted hydrogen, and carbon monoxide.

[0015] The near-zero carbon emission solar-coal complementary methane production system provided in this disclosure utilizes the condensate generated during coal gasification to electrolyze hydrogen through a hydrogen production component. This not only reduces the demand for fresh water resources but also achieves water resource recycling, thus lowering water consumption. The coal gasification component gasifies raw coal to produce carbon monoxide (CO), a process that releases the energy in coal more efficiently than direct coal combustion, thereby improving energy conversion efficiency. The methanation component converts carbon monoxide and hydrogen into methane, capturing most of the carbon and significantly reducing carbon dioxide (CO2) emissions, achieving the goal of near-zero carbon emissions. The near-zero carbon emission solar-coal complementary methane production system provided in this disclosure not only achieves the graded, clean, and efficient utilization of traditional fossil fuel coal but also improves the absorption of renewable energy solar energy, achieving near-zero carbon dioxide emissions and comprehensive cascade utilization of multiple energy sources, thus improving the energy efficiency of the near-zero carbon emission solar-coal complementary methane production system. Attached Figure Description

[0016] The above and other objects, features, and advantages of this disclosure will become clearer from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0017] Figure 1 A schematic diagram illustrating the composition of a near-zero carbon emission photovoltaic-coal complementary methane production system according to an embodiment of the present disclosure is shown.

[0018] Figure 2 A schematic top view of a gasifier according to an embodiment of the present disclosure is shown;

[0019] Figure 3 Schematic illustration Figure 2 A cross-sectional view of the gasifier shown in Figure AA;

[0020] Figure 4 A partial cross-sectional view of a burner according to an embodiment of the present disclosure is schematically shown; and

[0021] Figure 5 A schematic diagram illustrating the composition of a methanation assembly according to an embodiment of the present disclosure is shown.

[0022] 1-Coal gasification components;

[0023] 11-Gasifier;

[0024] 111 - Furnace body;

[0025] 1111 - Accommodation space;

[0026] 1112 - Feed pipe;

[0027] 1113 - Discharge port;

[0028] 1114 - Air distribution plate;

[0029] 1115 - Air cell;

[0030] 1116 - Air Intake;

[0031] 112 - External furnace wall;

[0032] 113 - External flue;

[0033] 1131 - Flue gas outlet;

[0034] 114 - Flue gas duct;

[0035] 115 - Tubular fittings;

[0036] 116 - Baffle plate;

[0037] 117 - Pipe fittings;

[0038] 12-Burner;

[0039] 121 - Central Passage;

[0040] 122 - Gas fuel passage;

[0041] 123 - Solid fuel channel;

[0042] 124 - Combustion-supporting channel;

[0043] 2- Hydrogen production assembly;

[0044] 3-Methanation Components;

[0045] 31-Reactor;

[0046] 32-Circulating compressor;

[0047] 33 - Desulfurization tank. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0050] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0051] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0052] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0053] In the process of realizing this disclosure, it was discovered that the clean and efficient utilization of coal is not only an energy security choice but also a crucial technology related to carbon peaking and carbon neutrality. Coal-to-natural gas (mainly composed of methane) is an important pathway for the clean conversion and utilization of coal, a vital means of optimizing energy structure and ensuring energy security, and an effective method for alleviating localized air pollution. Solar-powered water electrolysis for hydrogen production is a clean energy production method that can reduce carbon emissions and meets the requirements of sustainable development.

[0054] Figure 1 A schematic diagram of a near-zero carbon emission photovoltaic-coal complementary methane production system according to an embodiment of the present disclosure is shown.

[0055] As one aspect of this disclosure, a near-zero carbon emission photovoltaic-coal complementary methane production system is provided, as shown in Figure 1. The near-zero carbon emission photovoltaic-coal complementary methane production system includes a coal gasification unit 1, a hydrogen production unit 2, and a methanation unit 3. The coal gasification unit 1 is used to gasify raw coal to produce carbon monoxide (CO). The hydrogen production unit 2 is used to electrolyze the condensate (H2O) produced during the coal gasification process to produce hydrogen (H2). The methanation unit 3 is used to react the hydrogen produced by the hydrogen production unit with the carbon monoxide produced by the coal gasification unit 1 to produce methane (CH4).

[0056] The near-zero carbon emission solar-coal complementary methane production system provided in this disclosure utilizes the condensate generated during coal gasification via electrolysis in the hydrogen production component 2. This not only reduces the demand for fresh water resources but also achieves water resource recycling, thus lowering water consumption. The coal gasification component 1 gasifies raw coal to produce carbon monoxide (CO), a process that releases energy from coal more efficiently than direct coal combustion, thereby improving energy conversion efficiency. The methanation component 3 converts carbon monoxide and hydrogen into methane, capturing most of the carbon and significantly reducing carbon dioxide (CO2) emissions, achieving the near-zero carbon emission goal. The near-zero carbon emission solar-coal complementary methane production system provided in this disclosure not only achieves the graded, clean, and efficient utilization of traditional fossil fuel coal but also improves the absorption of renewable energy solar energy, achieving near-zero carbon dioxide emissions and comprehensive cascade utilization of multiple energy sources, thus improving the energy efficiency of the near-zero carbon emission solar-coal complementary methane production system.

[0057] According to embodiments of this disclosure, a coal gasification assembly 1 includes a pyrolysis furnace, a burner 12, a condenser, and a gasifier 11. The pyrolysis furnace is suitable for pyrolyzing raw coal to produce char and pyrolysis oil / gas. The burner 12 is suitable for burning the pyrolysis oil / gas with the aid of oxygen generated during electrolysis to obtain flue gas. The condenser is suitable for condensing the flue gas, separating condensate and carbon dioxide. The gasifier 11 is suitable for using carbon dioxide from the condenser as a gasifying agent to gasify the char from the pyrolysis furnace, producing carbon monoxide. The flue gas provides a high-temperature environment for the char gasification reaction before condensation. Furthermore, the flue gas also provides a medium-high temperature environment for the raw coal to undergo pyrolysis before condensation.

[0058] The efficient utilization of heat is achieved through the coal char and pyrolysis oil and gas produced in the pyrolysis furnace, and the combustion process of the pyrolysis oil and gas in burner 12. The flue gas provides a high-temperature environment for coal char gasification and a medium-high temperature environment for raw coal pyrolysis before condensation, reducing the need for external heat and improving overall energy efficiency. Oxygen generated during water electrolysis is used in burner 12 to aid combustion, reducing the formation of nitrogen oxides during combustion. Simultaneously, the condenser effectively separates moisture and removes carbon dioxide, using the carbon dioxide as a gasifying agent to reduce greenhouse gas emissions.

[0059] Figure 2 A schematic top view of a gasifier according to an embodiment of the present disclosure is shown. Figure 3 Schematic illustration Figure 2 The diagram shows a cross-sectional view of the gasifier AA.

[0060] According to embodiments of this disclosure, such as Figure 2 and Figure 3 As shown, the gasifier 11 includes a furnace body 111, an outer furnace wall 112, and a flue gas duct 114. The furnace body 111 forms an internal receiving space 1111, and the outer furnace wall 112 is located outside the furnace body 111, forming an external flue duct 113 between the furnace body 111 and the outer flue duct 112. The flue gas duct 114 is vertically installed within the receiving space 1111, and its upper part is connected to the external flue duct 113 via a pipe fitting 117. The burner 12 is installed on the furnace body 111 and located below the flue gas duct 114, providing flue gas from below. The flue gas rises within the flue gas duct to heat the downward-flowing coal char and the upward-flowing carbon dioxide within the receiving space 1111, causing the coal char to undergo a gasification reaction. The cooled flue gas is discharged through the external flue duct 113 and passes through a conveying pipe into the pyrolysis furnace, providing a medium-to-high temperature environment for the pyrolysis of raw coal.

[0061] According to the gasifier 11 of this disclosure, by vertically installing a flue gas duct 114 inside the furnace body 111 and supplying flue gas from the lower part of the flue gas duct 114 through a flue gas supply assembly, the flue gas rises inside the flue gas duct 114, which can indirectly and uniformly heat the gasification raw material flowing downward and the gasifying agent flowing upward in the containing space 1111. As the flue gas is discharged through the outer flue 113, the temperature of the containing space 1111 is kept at a high temperature, so that the gasification raw material undergoes a gasification reaction under the action of the gasifying agent and high temperature, which helps the gasification reaction to proceed fully and improves the gasification efficiency. By setting up flue gas duct 114 and external flue duct 113, high-temperature flue gas can be transferred to the containment space 1111 from the flue gas duct 114 and external flue duct 113 in opposite directions, which increases the contact area between the containment space 1111 and the high-temperature flue gas, realizes the multi-faceted radiation heat transfer mode, provides more uniform and stable heat to the containment space 1111, improves the uniformity of heating, improves the heat utilization efficiency of high-temperature flue gas, and reduces heat loss.

[0062] According to embodiments of this disclosure, such as Figure 3 As shown, the pipe fitting 117 is connected between the upper part of the flue gas duct 114 and the upper part of the furnace body 111. The flue gas outlet 1131 of the outer flue duct 113 is located at the lower part of the outer furnace wall 112. In this way, the residence time of the flue gas in the flue gas duct 114 and the outer flue duct 113 can be extended, thereby improving the heat exchange efficiency.

[0063] In one illustrative embodiment, as shown in the figure, the furnace body 111 includes, but is not limited to, being configured as a cylindrical or cubical structure.

[0064] In one illustrative embodiment, the outer furnace wall 112 can be constructed using refractory bricks and insulating castable, while the furnace body 111 can be constructed using refractory and heat-conducting materials. An annular external flue 113 is formed between the furnace body 111 and the outer furnace wall 112.

[0065] In one illustrative embodiment, the outer furnace wall 112 is constructed of silicon carbide refractory bricks and insulating castable, with an outer steel shell.

[0066] In one illustrative embodiment, fitting 117 can be a heat-resistant steel pipe lined with refractory material.

[0067] According to an embodiment of this disclosure, the upper part of the furnace body 111 is provided with a gas outlet (not shown in the figure), which is suitable for allowing the carbon monoxide (CO) gas generated by the gasification reaction of the gasification raw material (coal coke) and the gasifying agent (CO2) to be discharged.

[0068] According to embodiments of this disclosure, such as Figure 3 As shown, the bottom of the furnace body 111 is provided with a discharge port 1113, which is suitable for allowing the ash and slag generated after the coal coke undergoes gasification reaction to be discharged.

[0069] In one illustrative embodiment, the coal char undergoes a gasification reaction by reacting with carbon dioxide in a reverse manner under high temperature conditions. The target gas, which is mainly composed of CO, is drawn out from the gas outlet at the top of the gasification channel, and the harmless ash produced by gasification is discharged through the discharge port 1113 at the bottom.

[0070] According to embodiments of this disclosure, such as Figure 3 As shown, the furnace body 111 also includes a gas distribution plate 1114, which is obliquely installed between the periphery of the discharge port 1113 and the furnace body 111, forming a gas chamber 1115 adjacent to the receiving space 1111 between the gas distribution plate 1114 and the bottom and side walls of the furnace body 111. Carbon dioxide from the condenser enters the gas chamber 1115 through the inlet located at the bottom of the gas chamber 1115, passes through multiple through holes on the gas distribution plate 1114, and enters the receiving space 1111, contacting the coal and coke within the receiving space 1111. Ash and slag falling on the gas distribution plate 1114 are then discharged through the discharge port 1113.

[0071] In this embodiment, the pressure of the carbon dioxide gasifying agent can be stabilized through the gas chamber 1115, ensuring that the gasifying agent (i.e., CO2) can pass through the through holes on the gas distribution plate 1114 evenly, and further cooling the ash and slag around the discharge port 1113, ensuring that the temperature of the discharge port 1113 is controlled within the reasonable operating temperature range of the material.

[0072] In one illustrative embodiment, such as Figure 3 As shown, the gas distribution plate 1114 can be a conical structure and is made of heat-resistant steel. The bottom of the gas distribution plate 1114 is the discharge port 1113, which is connected to the outside and serves as the discharge channel for the gasified ash and slag.

[0073] In one illustrative embodiment, the gas distribution plate 1114 has uniformly distributed through holes. The gas distribution plate 1114 is used to support ash and slag and regulate the distribution of gasifying agent so that the gasifying agent entering the accommodating space 1111 is evenly distributed.

[0074] In one illustrative embodiment, the angle between the gas distribution plate 1114 and the horizontal plane can be between 15 and 70 degrees (e.g., 15, 20, 30, 45, 60, or 70 degrees) to promote the flow of residue to the discharge port 1113 and improve the distribution of the gasifying agent in the containment space 1111.

[0075] In such an embodiment, the gasifying agent passing through the gas distribution plate 1114 undergoes a gasification reaction with the coal char, and the remaining residue undergoes counter-current contact heat exchange, resulting in a decrease in the temperature of the residue and a preheating of the gasifying agent to the gasification reaction temperature.

[0076] According to embodiments of this disclosure, the gasifier further includes an air supply assembly (not shown in the figures). The air supply assembly is configured to blow loosening air toward the discharge port 1113 to prevent ash and slag from accumulating at the discharge port 1113.

[0077] In one illustrative embodiment, the gasifier also includes a valve (not shown) that cooperates with the loosening air assembly to allow or prevent the loosening air assembly from blowing loosening air toward the discharge port 1113.

[0078] According to embodiments of this disclosure, such as Figure 3 As shown, baffles 116 are arranged in the flue gas duct 113 and the outer flue duct 113, so that the flue gas flows along a serpentine path in the flue gas duct 114 and the outer flue duct 113, thereby prolonging the residence time of the flue gas in the flue gas duct 114 and the outer flue duct 113.

[0079] In one illustrative embodiment, the baffle 116 may be made of heat-resistant steel.

[0080] According to embodiments of this disclosure, the furnace body 111 further includes a feed pipe 1112, which passes through the outer furnace wall 112 and is installed at the top of the furnace body 111 to communicate with the receiving space 1111. Coal and coke enter the receiving space 1111 via the feed pipe 1112. A flue gas pipe 114 is located below the feed pipe 1112, and its top end is constructed in a conical shape to evenly disperse the coal and coke falling at the top of the flue gas pipe 114 within the receiving space 1111. This prevents raw material concentration and ensures a more uniform gasification reaction throughout the receiving space 1111, thus contributing to improved gasification efficiency.

[0081] According to an embodiment of this disclosure, the gasifier 11 further includes a tubular component 115. The tubular component 115 extends horizontally below and communicates with the flue gas duct 114, penetrating both opposite sides of the furnace body 111 to guide flue gas into the flue gas duct 114. Two burners 12 are symmetrically arranged at both ends of the tubular component 115 along its axial direction to provide flue gas by burning fuel (e.g., pyrolysis oil and gas from the pyrolysis furnace and oxygen from the hydrogen production unit).

[0082] In an alternative embodiment, the number of tubular components 115 can be multiple, with pairs of burners 12 symmetrically arranged at both ends of the axial direction of the tubular components 115, suitable for providing flue gas by burning fuel (e.g., pyrolysis oil and gas from a pyrolysis furnace and oxygen from a hydrogen production unit).

[0083] In one illustrative embodiment, the gasifier 11 further includes two tubular components 115, which are arranged perpendicularly to each other below the flue gas duct 114 and communicate with the flue gas duct 114. It is understood that the flue gas supply assembly may also include one or three tubular components 115, the specific number of which can be selected according to actual needs.

[0084] In one illustrative embodiment, each tubular component 115 has a pair of oppositely arranged burners 12 at both ends. Specifically, the combustion flame of each burner 12 is injected into the tubular component 115, giving the tubular component 115 the function of a furnace. Furthermore, the flue gas generated during combustion is discharged from the tubular component 115 and conveyed upwards into a flue gas duct 114, thereby stably and uniformly heating the coal char. The tubular component 115 may be made of, but is not limited to, heat-resistant steel.

[0085] In one illustrative embodiment, the bottom of the gas chamber 1115 is provided with an air inlet 1116 that allows the gasifying agent to enter, and the air inlet 1116 is arranged parallel to and opposite to the flue gas outlet 1131 and the burner 12.

[0086] Figure 4 A partial cross-sectional view of a burner according to an embodiment of the present disclosure is shown schematically.

[0087] According to embodiments of this disclosure, such as Figure 4 As shown, each burner 12 includes a central channel 121, a gaseous fuel channel 122, a solid fuel channel 123, and a combustion-supporting channel 124. The central channel 121 is used to supply primary air or oxygen into the tubular component 115. The gaseous fuel channel 122 is located around the central channel 121 and is used to deliver gaseous fuel (e.g., pyrolysis oil and gas from a pyrolysis furnace) into the tubular component 115, allowing the gaseous fuel to undergo preliminary combustion with primary air or oxygen at the nozzle tip. The solid fuel channel 123 is located around the gaseous fuel channel 122 and is used to deliver solid fuel into the tubular component 115. The combustion-supporting channel 124 is located around the solid fuel channel 123 and is used to deliver secondary air or oxygen into the tubular component 115 to mix with the solid fuel at the temperature provided by the preliminary combustion, allowing for complete combustion to provide flue gas. Both the primary and secondary oxygen can be oxygen generated from the hydrogen production assembly 2.

[0088] In an alternative embodiment, combustion of the fuel can take place inside the burner 12, with the high-temperature flue gas from the burner 12 being injected into the tubular component 115.

[0089] In this embodiment, the tubular component 115 introduces high-temperature flue gas into the flue gas duct 114. The high-temperature flue gas rises within the flue gas duct 114, enters the outer flue duct 113 through the tubular component 117, and is discharged from the flue gas outlet 1131. During the movement of the high-temperature flue gas, heat diffuses into the containing space 1111 through the walls of the flue gas duct 114 and the outer flue duct 113 on both sides of the containing space 1111. The multi-faceted radiation heat transfer method increases the heat transfer area, improves the heat supply per unit time, and reduces the lateral heat transfer radius between the gasification raw material and the heat source within the containing space 1111, ensuring the radiation intensity of the heat source and enabling timely and stable heating for the gasification process.

[0090] In one illustrative embodiment, the burner 12 can be cylindrical with a diameter between 200 and 400 mm. It employs a four-channel design, comprising, from the inside out, a central channel 121, a gaseous fuel channel 122, a solid fuel channel 123, and a combustion-supporting channel 124. Each channel is annular, with a width of 10 to 50 mm. The nozzles at the ends of the three outer channels narrow towards the central channel 121 at a horizontal angle of 10 to 30 degrees. Each channel end (the end closest to the tubular component 115) is protected by a cooling water jacket. The gaseous fuel undergoes initial combustion with primary air / oxygen at the nozzle at the end of the burner 12 (the end extending into the tubular component 115). Subsequently, within the tubular component 115, the solid fuel undergoes complete combustion with secondary air / oxygen, producing high-temperature flue gas.

[0091] In one illustrative embodiment, the flue gas outlet 1131 is located below the burner 12 and is arranged parallel to the burner 12. After heat exchange, the waste flue gas is discharged from the flue gas outlet 1131. The heat carried by the waste flue gas can be reused downstream through waste heat utilization methods such as heat exchangers and dryers.

[0092] According to embodiments of this disclosure, the coal gasification assembly further includes a dryer. The dryer is suitable for drying raw coal to obtain dried raw coal and water vapor, and then conveying the dried raw coal to a pyrolysis furnace for pyrolysis, while conveying the water vapor to the hydrogen production assembly 2. The conveying pipeline passes through the dryer after passing through the pyrolysis furnace to provide a medium-temperature environment for drying the raw coal. The other end of the conveying pipeline is connected to a condenser to condense the cooled flue gas.

[0093] In the process of implementing this disclosure, it was found that the moisture generated during the drying process of 1 ton of coal (generally 5% to 20%), together with the moisture in the high-temperature flue gas (the hydrogen content of coal is about 10%), produces about 250 kg. By making full use of the energy of the high-temperature flue gas, and adjusting the amount of coal and water fed in, the water source required for water electrolysis is used, avoiding the consumption of external water. This achieves the recycling of internal water in the near-zero carbon emission photovoltaic-coal complementary methane production system, thus saving water resources.

[0094] According to embodiments of this disclosure, the coal gasification assembly 1 involves processes such as drying, pyrolysis, coal coke and CO2 gasification and combustion.

[0095] The raw coal first enters the dryer, where it undergoes indirect heat exchange with the medium-temperature flue gas from the pyrolysis furnace to remove moisture. The dried coal is then fed into the pyrolysis furnace, where, under air-isolated and medium-to-high temperature conditions (600-900℃), a coal pyrolysis reaction occurs, producing high-temperature carbon-rich coal char and hydrogen-rich pyrolysis oil and gas. The pyrolysis oil and gas are sent to burner 12 to burn with oxygen generated from water electrolysis in hydrogen production unit 2, producing high-temperature flue gas (1000-1300℃) mainly composed of CO2 and water vapor. Meanwhile, the solid-phase high-temperature coal char enters gasifier 11 and reacts with CO2 gasifying agent to produce CO. Since coal pyrolysis, coal char, and CO2 gasification are all strongly endothermic reactions, the required heat is mainly provided indirectly through the high-temperature flue gas (1000-1300℃) generated by burner 12.

[0096] High-temperature flue gas (1000-1300℃) provides the heat required for the gasification reaction of coal char and CO2 through indirect heating. The resulting medium-high temperature flue gas (700-1000℃) further indirectly heats the coal pyrolysis reaction. Subsequently, the obtained medium-temperature flue gas (300-500℃) is used to further dry the raw coal and remove moisture. The resulting low-temperature flue gas (100-150℃) is separated into CO2 and moisture by a condenser. The CO2 is recycled to the gasifier 11 as a gasifying agent, while the moisture, along with the moisture removed from the coal drying process, serves as the water source for subsequent water electrolysis to produce hydrogen.

[0097] According to embodiments of this disclosure, such as Figure 1 As shown, the hydrogen production assembly 2 includes an electrolyzer and a photovoltaic panel. The electrolyzer is used to receive condensate, and the photovoltaic panel is used to convert solar energy into electrical energy to electrolyze the condensate in the electrolyzer.

[0098] According to an embodiment of the present disclosure, a near-zero carbon emission solar-coal complementary methane production system couples solar-powered water electrolysis to produce hydrogen. The generated green hydrogen is then reacted with CO produced by the coal gasification unit 1 through a methanation reaction to obtain methane. This solar-coal complementary methane production system improves the utilization of renewable energy, reduces the consumption of coal fossil fuels, achieves zero CO2 emissions, and significantly reduces environmental pollution.

[0099] According to embodiments of this disclosure, such as Figure 1 As shown, the hydrogen production assembly 2 also includes a water purifier, which is suitable for filtering condensate before it enters the electrolyzer.

[0100] According to embodiments of this disclosure, the hydrogen production unit 2 uses solar photovoltaic power to generate electricity and uses the condensate from the coal gasification unit 1 as a water source to produce hydrogen and oxygen through green electricity-driven water electrolysis. Oxygen and high-temperature pyrolysis oil and gas undergo oxygen-enriched combustion, and the heat generated is used for coal pyrolysis and the gasification reaction of coal char and CO2. Hydrogen and CO produced by the coal gasification unit 1 are converted into methane through a methanation reaction.

[0101] Figure 5 A schematic diagram illustrating the composition of a methanation assembly according to an embodiment of the present disclosure is shown.

[0102] According to embodiments of this disclosure, such as Figure 5 As shown, the methanation assembly 3 includes multiple cascaded reactors 31. These cascaded reactors 31 are suitable for the staged methanation reaction of carbon monoxide from the gasifier 11 and hydrogen from the hydrogen production assembly 2 under the action of a catalyst. Specifically, following the flow direction of carbon monoxide, a portion of the product gas produced in the downstream reactor 31 is circulated back to the first-stage reactor 31 via a recirculation compressor 32 to control the temperature of the first-stage reactor. The product gas may include methane and unreacted hydrogen and carbon monoxide.

[0103] According to embodiments of this disclosure, the ratio of H2 to CO in the syngas can be adjusted to meet the requirements of the methanation reaction. In the methanation reactor 31, H2 and CO react to produce methane (CH4) under certain temperature, pressure, and catalyst conditions. The methane, water, and other gases (such as unreacted H2 and CO) in the methanation reaction products are separated to obtain a high concentration of methane (CH4) gas.

[0104] In one illustrative embodiment, such as Figure 4 As shown, the methanation assembly 3 also includes a desulfurization tank 33, which is used to desulfurize the raw gas from the gasifier 11 (carbon monoxide) and the hydrogen from the hydrogen production assembly 2. Based on the near-zero carbon emission solar-coal complementary methane production system provided in this disclosure embodiment, and combining the excellent characteristics of solar water electrolysis hydrogen production technology, a near-zero carbon emission solar-coal complementary methane production system has been developed. Solar power is used to generate electricity, and water is decomposed into hydrogen and oxygen through electrolysis. The oxygen is fully combusted with the pyrolysis oil and gas generated by the coal gasification assembly 1, and the released heat is supplied to the endothermic reaction of coal pyrolysis and the gasification reaction of coal char and CO2. This causes the coal char to react with CO2 to produce CO, which then undergoes a methanation reaction with the green H2 produced by water electrolysis to obtain methane products.

[0105] In one illustrative embodiment, raw coal in 0-30mm pulverized form or 30-80mm block form is first conveyed to a dryer via a screw conveyor, where it undergoes indirect heat exchange with medium-temperature flue gas (300-500℃) from the pyrolysis furnace to remove free moisture from the coal. The dried block coal is then further fed into the pyrolysis furnace, which can be selected from moving bed, fluidized bed, rotating bed, or rotary furnace types depending on the characteristics of the coal raw material. Under air-isolated and medium-to-high temperature conditions (600-900℃), the coal undergoes a pyrolysis reaction to generate high-temperature carbon-rich coal char and hydrogen-rich pyrolysis oil and gas. The pyrolysis oil and gas are sent to burner 12 to burn with oxygen generated by photovoltaic water electrolysis, producing high-temperature flue gas (1000-1300℃) with CO2 and water vapor as the main components; while solid high-temperature coal coke enters gasifier 11 and reacts with CO2 gasifying agent to generate CO; since the coal pyrolysis and the gasification reactions of coal coke and CO2 are all strongly endothermic reactions, the heat required is mainly provided indirectly through the high-temperature flue gas (1000-1300℃) generated by burner 12.

[0106] High-temperature flue gas (1000-1300℃) provides the heat required for the gasification reaction of coal char and CO2 through indirect heating. The resulting medium-high temperature flue gas (700-1000℃) further indirectly heats the coal pyrolysis reaction. Subsequently, the obtained medium-temperature flue gas (300-500℃) is used to further dry the raw coal and remove moisture from the coal. The obtained low-temperature flue gas (100-150℃) is separated into CO2 and moisture by a condenser. The CO2 is recycled to the gasifier 11 as a gasifying agent, while the moisture, together with the moisture obtained from coal drying, is used as a water source for subsequent electrolysis of water to produce hydrogen.

[0107] A photovoltaic panel can be composed of multiple photovoltaic cells (e.g., silicon-based materials). When sunlight shines on the photovoltaic panel, photons interact with the semiconductor material in the panel, generating an electron flow that produces direct current (DC). This electrical energy is then transmitted to an electrolytic cell. The electrolytic cell is filled with condensate from coal gasification components, and the operating temperature range is 25-80°C.

[0108] Hydrogen and oxygen are produced by using green electricity (solar energy) to power water in an alkaline electrolyzer.

[0109] 2H₂O = Electrolysis = 2H₂↑ + O₂↑.

[0110] The electrolytic cell mainly consists of a protective plate, electrode plates, contact electrode plates, a diffusion layer, and a membrane electrode assembly (MEA). The electrolyte, controlled to a set temperature by a constant-temperature water bath, is pumped to the liquid inlet of the electrolytic cell and then enters the microchannels in the electrode plates. It diffuses on the diffusion layer, forming a uniform electrolyte film on the MEA. In the anode region of the MEA, the liquid film electrolyzes to generate O2, H+, and 2e. The generated O2 is discharged through the electrolyte outlet on the anode side, while the generated H+ enters the cathode region through the exchange membrane, and the generated 2e is transferred to the cathode through an external circuit. In the cathode region, the liquid film transfers H+ to the cathode. H+ combines with 2e on the cathode to generate H2, which is discharged through the electrolyte outlet on the cathode side.

[0111] The chemical equation for the gasification reaction of coal char and CO2 is as follows:

[0112] CO + 3H₂ → CH₄ + H₂O;

[0113] Wherein, △H 298K =-206.28kJ / mol. Under normal circumstances, the temperature rise of 74℃ can be generated for every 1% conversion of CO.

[0114] The methanation assembly 3 includes three cascaded adiabatic fixed-bed reactors 31, which are arranged in the order of CO flow direction as the first-stage reactor, the second-stage reactor, and the third-stage reactor.

[0115] The first-stage reactor and the second-stage reactor are connected in series (or in series-parallel). Part of the product gas produced by the second-stage reactor is used as circulating gas to control the bed temperature of the first-stage reactor, with a circulating temperature of 60–150°C. The outlet temperature of the first-stage reactor is approximately 650°C, and the outlet temperature of the second-stage reactor is 500–650°C.

[0116] High-pressure superheated steam is produced by recovering heat from the steam superheater and waste boiler located at the outlet of the first-stage reactor 31 and the waste boiler located at the outlet of the second-stage reactor 31. High-concentration CH4 gas is discharged from the third-stage reactor 31, and the unreacted mixed gas is recycled back into the circulating compressor for reaction.

[0117] The methanation process requires the feedstock gas modulus to be slightly greater than 3 and the total sulfur content to be no more than 0.1 × 10⁻⁶. −6 A separate desulfurization tank 31 is installed to reduce the total sulfur content in the feed gas (carbon monoxide from gasifier 11 and hydrogen from hydrogen production unit 2) to 30 × 10⁻⁶. −9 The following describes the process. The first, second, and third stage reactors are filled with nickel-based or alumina catalysts.

[0118] Conventional industrial boilers typically produce 2.66 to 2.72 tons of CO2 per ton of standard coal burned, with the exact figure depending on coal quality and gasification conditions. One ton of carbon, when completely burned in oxygen, produces approximately 3.67 tons of CO2 (based on the ratio of carbon atomic weight to CO2 molecular weight). The near-zero carbon emission photovoltaic-coal complementary methane production system provided in this disclosure decouples the traditional one-step coal gasification process into a staged gasification process, pyrolyzing coal to produce char, thus achieving the cascaded utilization and orderly conversion of coal chemical energy and reducing irreversible losses during gasification. By adjusting the amount of coal and the CO2 produced from O2 combustion, and using CO2 as a gasifying agent, natural enrichment of carbon components is achieved, resulting in high-concentration CO and near-zero CO2 emissions.

[0119] The near-zero carbon emission solar-coal complementary methane production system provided in this embodiment uses solar-powered water electrolysis to produce oxygen, which is then fully combusted with the high-temperature flue gas generated during the hydrogen-rich pyrolysis process of coal. Through the cascade utilization of the waste heat of the high-temperature flue gas, the system provides the required heat for the gasification reaction, pyrolysis, and drying processes of coal coke and CO2, thus fully realizing the cascade utilization and full utilization of heat and greatly improving the energy utilization level of the system.

[0120] In the near-zero carbon emission solar-coal complementary methane production system provided in this embodiment, the staged gasification cold gas efficiency of the coal gasification component 1 reaches over 85%, which is 8-10 percentage points higher than that of the traditional Texaco gasification technology. This improvement means that, with the same raw coal consumption, the staged gasification technology coupled with a solar-powered water electrolysis system can generate more CH4 with higher chemical energy, thereby improving the energy conversion efficiency and economic benefits of the entire gasification system.

[0121] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A near-zero carbon emission solar-coal complementary methane production system, characterized in that, include: Coal gasification components are suitable for gasifying raw coal to produce carbon monoxide. The hydrogen production assembly is suitable for electrolyzing the condensate produced during the gasification of the raw coal to produce hydrogen. as well as A methanation assembly is suitable for causing the hydrogen produced by the hydrogen production assembly and the carbon monoxide produced by the coal gasification assembly to undergo a methanation reaction to obtain methane. The coal gasification assembly includes: A pyrolysis furnace is suitable for pyrolyzing the raw coal to produce coal char and pyrolysis oil and gas; A burner is suitable for burning the pyrolysis oil and gas with the aid of oxygen generated during the electrolysis process to obtain flue gas; A condenser suitable for condensing the flue gas and separating the condensate and carbon dioxide; and A gasifier is suitable for using carbon dioxide from the condenser as a gasifying agent to gasify coal char from the pyrolysis furnace, producing carbon monoxide, wherein the flue gas provides a high-temperature environment for the coal char gasification reaction before condensation; wherein the flue gas also provides a medium-high temperature environment for the raw coal to undergo pyrolysis before condensation; the gasifier includes: The furnace body has an internal storage space. An outer furnace wall is provided on the outside of the furnace body, forming an external flue between the wall and the furnace body; and The flue gas duct is installed vertically within the accommodating space, and the upper part of the flue gas duct is connected to the external flue gas duct through a pipe fitting; The burner is mounted on the furnace body and located below the flue gas duct. It is used to supply flue gas from below to the flue gas duct. The flue gas rises in the flue gas duct to heat the coal coke flowing downward and the carbon dioxide flowing upward in the containment space, causing the coal coke to undergo a gasification reaction. The cooled flue gas is discharged through the outer flue and passes through the pyrolysis furnace through the conveying pipe, providing the medium-high temperature environment for the pyrolysis of the raw coal.

2. The methane production system according to claim 1, characterized in that, The furnace body also includes: A feed pipe is installed on the top of the furnace body through the outer furnace wall to communicate with the receiving space, wherein the coal and coke enter the receiving space via the feed pipe; The flue gas duct is located below the feed duct, and the top of the flue gas duct is constructed into a cone shape so that the coal and coke falling on the top of the flue gas duct are evenly dispersed in the receiving space.

3. The methane production system according to claim 1, characterized in that, The gasifier also includes: A tubular component extends horizontally below the flue gas duct and communicates with the flue gas duct. The tubular component penetrates the two opposite sides of the furnace body to guide the flue gas into the flue gas duct. The burner consists of two units, symmetrically arranged at both ends of the tubular component along its axial direction, to provide flue gas by burning fuel.

4. The methane production system according to claim 1, characterized in that, The bottom of the furnace body is provided with a discharge port, which is suitable for allowing the ash and slag generated after the coal coke undergoes the gasification reaction to be discharged. The furnace body also includes: An air distribution plate is installed at an angle between the periphery of the discharge port and the furnace body, so that an air chamber adjacent to the receiving space is formed between the air distribution plate and the bottom and side walls of the furnace body; Carbon dioxide from the condenser enters the gas chamber through the inlet located at the bottom of the gas chamber, passes through multiple through holes on the gas distribution plate into the containment space, comes into contact with the coal char in the containment space, and causes the ash and slag falling on the gas distribution plate to be discharged through the outlet.

5. The methane production system according to claim 1, characterized in that, The coal gasification assembly also includes: A dryer is used to dry the raw coal to obtain dried raw coal and water vapor, and to transport the dried raw coal to the pyrolysis furnace for pyrolysis, and to transport the water vapor to the hydrogen production unit; The conveying pipeline passes through the pyrolysis furnace and then through the dryer to provide a medium-temperature environment for drying the raw coal. The other end of the conveying pipeline is connected to the condenser to condense the cooled flue gas.

6. The methane production system according to any one of claims 1-5, characterized in that, The hydrogen production assembly includes: An electrolytic cell suitable for receiving the condensate; and Photovoltaic panels are suitable for converting solar energy into electrical energy to electrolyze condensate in the electrolytic cell.

7. The methane production system according to claim 6, characterized in that, The hydrogen production assembly also includes: A water purifier suitable for filtering the condensate before it enters the electrolytic cell.

8. The methane production system according to any one of claims 1-5, characterized in that, The methanation assembly includes: Multiple cascaded reactors are suitable for causing carbon monoxide from the gasifier and hydrogen from the hydrogen production unit to undergo the methanation reaction in stages under the action of a catalyst. In this process, the product gas generated by the downstream reactor, following the flow direction of the carbon monoxide, is used as a circulating gas to control the temperature of the reactor in the first stage. The product gas includes the methane, unreacted hydrogen, and carbon monoxide.

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