Underground coal gasification gas upgrading system

Abstract

The utility model discloses an underground gasification coal gas upgrading system belongs to underground gasification coal gas upgrading technical field, including decarburization unit, including the decarburization reactor of inside setting up alkaline solution, and alkaline solution absorbs carbon dioxide in coal gas before upgrading, and generates acid carbonate and exports through the tapping hole of decarburization reactor, hot decomposition unit is used to carry out the thermal decomposition to acid carbonate, and the mixed gas of water solution is alkaline gas and carbon dioxide, decarburization unit, including the decarburization reactor of inside setting up electrophilic reagent, and electrophilic reagent separates carbon dioxide in mixed gas, and generates coordination compound, and regenerative unit, carries out the thermal decomposition to coordination compound, and the mixed gas of water solution is alkaline gas and electrophilic reagent. The utility model discloses through the recycling of system internal material realizes low temperature, low energy consumption, simple equipment can separate underground gasification coal gas into carbon dioxide and with effective component as the main high quality coal gas.

Description

Technical Field

[0001] This utility model belongs to the field of underground gasification gas upgrading technology, and in particular relates to an underground gasification gas upgrading system. Background Technology

[0002] Underground coal gasification is a chemical mining technology that converts coal into combustible gas through controlled underground combustion. This technology integrates well construction, mining, and gasification processes. It can not only recover abandoned coal resources from mines but also be used to mine thin coal seams, deep coal seams, coal seams under pressure ("three-level" pressure), and high-sulfur, high-ash, and high-gas coal seams that are difficult or economically unfeasible to mine underground. The gas produced by underground gasification can be used directly for domestic consumption and power generation, and can also be used to extract pure hydrogen or as feedstock for synthetic oils, dimethyl ether, ammonia, and methanol. Therefore, underground coal gasification technology has good economic and environmental benefits, greatly improving the utilization rate and level of coal resources, and is an important research and development direction for clean coal technology in my country.

[0003] Unlike surface coal gasification technology, underground coal gasification produces coal gas with a relatively high carbon dioxide content, which is closely related to the composition of the gasifying agent. In underground coal gasification, when air is used as the gasifying agent, the volume fraction of carbon dioxide in the coal gas is above 20%, with nitrogen being the most abundant gas. As the oxygen concentration in the air increases, the volume fraction of carbon dioxide in the produced coal gas gradually increases, reaching a maximum of 55%. However, when carbon dioxide and oxygen are used as gasifying agents, as the oxygen concentration in the gasifying agent increases, the volume fraction of carbon dioxide in the produced coal gas gradually decreases from over 70% to around 40%.

[0004] The volume fraction of effective components (combustible gases such as H2, CO, and CH4) in coal gas is typically between 20% and 60%. This low content of effective components limits the application range of underground gasified coal gas and reduces its added value. To broaden the application range and increase its added value, decarbonization of coal gas (especially coal gas produced using oxygen-enriched carbon dioxide as a gasifying agent) is one of the most efficient measures. Currently, coal gas decarbonization methods mainly include physical absorption methods (pressurized water absorption, methanol washing, etc.), chemical absorption methods (ethanolamine method, diethanolamine method, and catalytic thermal potassium alkali method, etc.), and membrane separation methods. These methods involve decarbonization systems that are either energy-intensive, have high equipment requirements (high temperature and pressure resistance, acid and alkali corrosion resistance, etc.), or fail to fully utilize the recycling capacity of the materials within the system. Summary of the Invention

[0005] To address the problems existing in the prior art, this utility model provides an underground gasification gas upgrading system. Through the recycling of materials within the system, it achieves low temperature, low energy consumption, and simple equipment to separate underground gasification gas into carbon dioxide and high-quality gas with effective components as the main components.

[0006] This utility model is implemented as follows: an underground gasification gas upgrading system, comprising:

[0007] The decarbonization unit includes a decarbonization reactor containing an alkaline solution. The inlet of the decarbonization reactor is connected to the outlet pipeline of the pre-upgrading coal gas. The gas discharged from the outlet of the decarbonization reactor is the upgraded coal gas. The alkaline solution absorbs the carbon dioxide in the pre-upgrading coal gas and generates acidic carbonates which are discharged through the slag outlet of the decarbonization reactor.

[0008] The thermal decomposition unit is used to thermally decompose acidic carbonates to generate a mixture of gas and carbon dioxide in an aqueous solution. The mixture is discharged through the exhaust port of the thermal decomposition unit.

[0009] The deammoniation unit includes a deammoniation reactor containing an electrophilic reagent. The inlet of the deammoniation reactor is connected to the outlet of the pyrolysis unit. The electrophilic reagent separates carbon dioxide from the mixed gas and generates a coordination compound. The coordination compound is discharged through the outlet of the deammoniation reactor.

[0010] The regeneration unit thermally decomposes the coordination compound to generate an alkaline gas and an electrophilic reagent in aqueous solution. The gas is then transported to the decarbonization unit, and the electrophilic reagent is transported to the deammoniation unit.

[0011] Furthermore, the upper end of the decarbonization reactor is provided with an inlet pipe connected to an external liquid supply pipeline, and a spray component connected to the inlet pipe is provided inside the decarbonization reactor. The spray component allows the alkaline solution to be sprayed and come into countercurrent contact with the coal gas. The gas released by the regeneration unit is transported to the inlet pipe of the decarbonization reactor through the gas outlet of the regeneration unit via a pipeline.

[0012] Furthermore, the decarbonization reactor is equipped with a gas distribution plate, the gas inlet of which is connected to the gas inlet of the decarbonization reactor, and the gas distribution plate disperses the coal gas into the alkaline solution.

[0013] Furthermore, both the pyrolysis unit and the regeneration unit are equipped with a heating section. The heating section is a partitioned heat exchange structure, and the heat source is the gas from the outlet of the underground gasifier. The gas from the outlet of the underground gasifier first undergoes heat exchange in the heating section of the regeneration unit, and then is transported to the heating section of the pyrolysis unit through pipelines for heat exchange.

[0014] Furthermore, the feed inlet of the deammoniation reactor is located at the top of the deammoniation reactor, and the discharge inlet of the deammoniation reactor is located at the bottom. A funnel-shaped gas distribution plate is provided in the deammoniation reactor, and the gas distribution plate is provided with multiple vent holes. The gas distribution plate divides the inner cavity of the deammoniation reactor into upper and lower chambers. The electrophilic reagent is placed in the upper chamber. The lowest point of the gas distribution plate is connected to the discharge inlet of the deammoniation reactor. The gas inlet of the deammoniation reactor is located in the middle of the lower chamber, and the gas outlet of the deammoniation reactor is located in the upper-middle part of the upper chamber.

[0015] Furthermore, the carbon dioxide separated in the deammoniation unit is discharged through the outlet of the deammoniation reactor, the inlet of the decarbonization reactor is located below the surface of the alkaline solution, and the outlet of the decarbonization reactor is located above the surface of the alkaline solution; the inlet of the deammoniation reactor is located at the lower part of the electrophilic reagent packing moving bed.

[0016] Furthermore, the decarbonization reactor is equipped with a first temperature measuring element for monitoring the temperature of the solution inside the container and a pH monitoring element for monitoring the pH value of the solution inside the container.

[0017] Furthermore, the thermal decomposition unit is equipped with a second temperature measuring element for monitoring the reaction temperature, and the regeneration unit is equipped with a third temperature measuring element for monitoring the reaction temperature.

[0018] Furthermore, the alkaline solution is ammonia water, the generated acidic carbonate is ammonium bicarbonate, the alkaline gas in the aqueous solution is ammonia, the electrophilic reagent is anhydrous cobalt chloride particles or anhydrous calcium chloride particles, preferably anhydrous calcium chloride particles, and the coordination compound is calcium chloride-ammonia compound.

[0019] Furthermore, the feed port of the pyrolysis unit is connected to the slag outlet of the decarbonization reactor; the feed port of the regeneration unit is connected to the discharge port of the deammoniation reactor.

[0020] The advantages and technical effects of this utility model are as follows: By adopting the above-mentioned technical solution, the underground gasification gas can be separated into carbon dioxide and high-quality gas with effective components, using low temperature, low energy consumption, and simple equipment through the recycling of materials within the system. Furthermore, the thermal energy carried by the gas can be utilized in a cascade manner. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure provided in an embodiment of the present utility model.

[0022] Figure 2 This is a schematic diagram of the structure of each unit provided in the embodiment of this utility model.

[0023] In the diagram: 1. Decarbonization unit; 1-1. Decarbonization reactor; 1-2. Inlet of decarbonization reactor; 1-3. Outlet of decarbonization reactor; 1-4. Slag outlet of decarbonization reactor; 1-5. Liquid inlet of decarbonization reactor; 1-6. Gas distribution plate; 2. Thermal decomposition unit; 2-1. Thermal decomposition reactor; 2-2. Feed inlet of thermal decomposition unit; 2-3. Exhaust outlet of thermal decomposition unit; 3. Ammonia removal unit; 3-1. Ammonia removal reactor; 3-2. Inlet of ammonia removal reactor; 3-3. Discharge outlet of ammonia removal reactor; 3-4. Outlet of ammonia removal reactor; 3-5. Feed inlet of ammonia removal reactor; 3-6. Gas distribution plate; 4. Regeneration unit; 4-1. Regeneration reactor; 4-2. Feed inlet of regeneration unit; 4-3. Outlet of regeneration unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0025] It should be noted that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0026] like Figure 1 and Figure 2 As shown, this application provides an underground gasification gas upgrading system, including a decarbonization unit 1, a thermal decomposition unit 2, a deammoniation unit 3, and a regeneration unit 4.

[0027] The decarbonization unit 1 uses an alkaline solution to absorb carbon dioxide from the coal gas and generate acidic carbonates. It includes a decarbonation reactor 1-1 with an internal alkaline solution. The inlet 1-2 of the decarbonation reactor is connected to the outlet pipeline of the pre-upgrading coal gas. The outlet 1-3 of the decarbonation reactor discharges the upgraded coal gas. The alkaline solution absorbs carbon dioxide from the pre-upgrading coal gas and generates acidic carbonates, which are then discharged through the slag outlet 1-4 of the decarbonation reactor.

[0028] Thermal decomposition unit 2 is used to thermally decompose acidic carbonates to generate a mixture of gas with an alkaline aqueous solution and carbon dioxide. The mixture is discharged through the exhaust port 2-3 of the thermal decomposition unit.

[0029] The deammoniation unit 3 uses an electrophilic reagent to separate carbon dioxide from the mixed gas and generate coordination compounds. It includes a deammoniation reactor 3-1 internally equipped with an electrophilic reagent. The inlet 3-2 of the deammoniation reactor is connected to the exhaust port of the pyrolysis unit. The electrophilic reagent separates carbon dioxide from the mixed gas and generates coordination compounds, which are then discharged through the outlet 3-3 of the deammoniation reactor.

[0030] In the regeneration unit 4, the coordination compound is thermally decomposed to generate an alkaline gas and an electrophilic reagent. The alkaline gas is then transported to the decarbonization unit 1, and the electrophilic reagent is transported to the deammoniation unit 3.

[0031] Specifically, the effective gases in the coal gas (H2, CO, CH4, etc.) are neutral gases, which are sparingly soluble in water and acidic / alkaline solutions. Carbon dioxide, on the other hand, is an acidic gas, slightly soluble in water, and can be absorbed by alkaline solutions. Therefore, an alkaline solution is set in the decarbonization reactor. Before upgrading, the coal gas has a high concentration of carbon dioxide. The alkaline solution is connected to the inlet 1-2 of the decarbonization reactor through a pipeline. The alkaline solution absorbs the carbon dioxide in the high-concentration carbon dioxide coal gas and discharges the upgraded coal gas, i.e., low-concentration carbon dioxide coal gas, through the outlet 1-3 of the decarbonization reactor for subsequent collection or use.

[0032] The acidic carbonates generated after the alkaline solution absorbs carbon dioxide are discharged through the slag outlet 1-4 of the decarbonation reactor. The acidic carbonate crystals are collected, drained, and then transported to the thermal decomposition unit 2 through the feed inlet 2-2. The thermal decomposition unit 2 decomposes the acidic carbonates by heating them into a gaseous solution (alkaline), a mixture of water and carbon dioxide, and the resulting gas mixture is transported to the inlet 3-2 of the deammoniation reactor through the exhaust outlet 2-3. The thermal decomposition unit 2 includes the thermal decomposition reactor 2-1. It is understood that the feed inlet 2-2 of the thermal decomposition unit refers to the feed inlet of the thermal decomposition reactor 2-1, and the exhaust outlet 2-3 refers to the exhaust outlet installed on the thermal decomposition reactor 2-1.

[0033] In the deammoniation reactor 3-1, the mixed gas comes into full contact with the electrophilic reagent particles. Carbon dioxide in the mixed gas is separated and discharged through the gas outlet 3-4 of the deammoniation reactor for subsequent collection or use. The gas, which is alkaline in aqueous solution, forms a coordination compound with the electrophilic reagent.

[0034] The coordination compound is discharged through the discharge port 3-3 of the deammoniation reactor and transported through a pipeline to the feed port 4-2 of the regeneration unit. In the regeneration unit 4, the coordination compound particles decompose upon heating, releasing an alkaline gas from the aqueous solution. This alkaline gas is then transported through the outlet port 4-3 of the regeneration unit to the decarbonization unit 1. The remaining electrophilic reagent particles are returned to the deammoniation reactor 3-1 in the deammoniation unit 3 to reabsorb the alkaline gas from the aqueous solution. The regeneration unit 4 includes the regeneration reactor 4-1. It is understood that the feed port 4-2 of the regeneration unit refers to the feed port of the regeneration reactor 4-1, and the outlet port 4-3 of the regeneration unit refers to the outlet port installed on the regeneration reactor 4-1.

[0035] Furthermore, the upper end of the decarbonization reactor is provided with an inlet pipe connected to an external liquid supply pipeline, and a spray component connected to the inlet pipe is provided inside the decarbonization reactor. The spray component allows the alkaline solution to be sprayed and come into countercurrent contact with the coal gas. The alkaline gas released by the regeneration unit 4 is transported from the gas outlet 4-3 of the regeneration unit to the inlet 1-5 of the decarbonization reactor through a pipeline.

[0036] Specifically, the inlet pipe 1-5 of the decarbonization reactor is connected to the external liquid supply pipeline, and the alkaline gas released by the regeneration unit 4 is transported to the inlet pipe 1-5 of the decarbonization reactor through the pipeline to further effectively generate an alkaline solution. The alkaline solution is sprayed through the spray component and comes into countercurrent contact with the coal gas, which improves the contact efficiency between the alkaline solution and the carbon dioxide in the coal gas and promotes the absorption of carbon dioxide.

[0037] Furthermore, a gas distribution plate 1-6 is provided inside the decarbonization reactor. The gas inlet of the gas distribution plate 1-6 is connected to the gas inlet 1-2 of the decarbonization reactor. The gas distribution plate 1-6 disperses the coal gas into the alkaline solution. Specifically, the gas distribution plate 1-6 is provided with multiple gas outlets. The coal gas before upgrading enters the gas distribution plate 1-6 through the gas inlet 1-2 of the decarbonization reactor and is dispersed into the alkaline solution through the gas outlets of the gas distribution plate 1-6. In some embodiments, the gas distribution plate 1-6 may take the form of a coil structure, a membrane disc type, or a branch structure composed of multiple connecting pipes, etc., and the gas outlets on the gas distribution plate 1-6 may be evenly distributed, proportionally distributed, or irregularly distributed.

[0038] Furthermore, the decarbonation reactor is equipped with a first temperature sensing element for monitoring the temperature of the solution inside the container and a pH monitoring element for monitoring the pH value of the solution inside the container. Since excessively high temperatures within the decarbonation reactor may cause the generated acidic carbonates to decompose, while excessively low temperatures would result in a low reaction rate for the alkaline solution to absorb carbon dioxide, the first temperature sensing element is needed to monitor the solution temperature within the decarbonation reactor to ensure reaction efficiency and absorption effectiveness. Simultaneously, maintaining the solution's pH value in an alkaline state is beneficial for carbon dioxide absorption; therefore, a pH monitoring element is needed to monitor the pH value of the solution inside the container. The first temperature sensing element can be a temperature sensor, and the pH monitoring element can be a pH sensor.

[0039] In one embodiment, the feed port 2-2 of the pyrolysis unit is connected to the slag outlet 1-4 of the decarbonization reactor; the feed port 4-2 of the regeneration unit is connected to the discharge port 3-3 of the deammoniation reactor.

[0040] In one embodiment, the carbon dioxide separated in the deammoniation unit 3 is discharged through the outlet 3-4 of the deammoniation reactor.

[0041] In one embodiment, the feed inlet 3-5 of the deammoniation reactor is located at the top of the deammoniation reactor 3-1, and the discharge inlet 3-3 of the deammoniation reactor is located at the bottom. A funnel-shaped gas distribution plate 3-6 is provided in the deammoniation reactor 3-1, and the gas distribution plate 3-6 is provided with multiple vent holes. The gas distribution plate 3-6 divides the inner cavity of the deammoniation reactor 3-1 into upper and lower chambers. The electrophilic reagent is placed in the upper chamber. The lowest point of the gas distribution plate 3-6 is connected to the discharge inlet of the deammoniation reactor 3-1. The air inlet of the deammoniation reactor 3-1 is located in the middle of the lower chamber, and the air outlet 3-4 of the deammoniation reactor is located in the upper-middle part of the upper chamber.

[0042] Furthermore, the thermal decomposition unit 2 is equipped with a second temperature sensing element for monitoring the reaction temperature, and the regeneration unit 4 is equipped with a third temperature sensing element for monitoring the reaction temperature. In the thermal decomposition unit 2, the reaction temperature for the thermal decomposition of acidic carbonates needs to be maintained; therefore, a second temperature sensing element is installed in the thermal decomposition unit 2 for monitoring. In the regeneration unit 4, to ensure complete release of the alkaline gas from the aqueous solution, the thermal decomposition of the coordination compound needs to be carried out under high-temperature conditions; therefore, a third temperature sensing element is installed in the regeneration unit 4 for monitoring. Both the second and third temperature sensing elements can be temperature sensors.

[0043] Furthermore, both the pyrolysis unit 2 and the regeneration unit 4 are equipped with heating sections. To fully utilize the heat carried by the gas from the underground gasification outlet (the gas temperature at the wellhead is typically above 150°C), the heating section is a partitioned heat exchange structure, with the heat source being the gas from the underground gasifier outlet. The gas from the underground gasifier outlet first undergoes heat exchange in the heating section of the regeneration unit 4, and then is transported via pipeline to the heating section of the pyrolysis unit 2 for further heat exchange, thus achieving cascaded utilization of the heat energy carried by the gas. Specifically, using the high-temperature gas (above 250°C) from the underground gasifier outlet as the heat source, it first enters the heating section of the regeneration unit 4 for heat exchange, controlling the temperature within the regeneration unit 4 to be 250°C or higher. The regeneration unit 4 is equipped with an electric heating system, which is activated to supplement heat when the gas heat is insufficient. After heat exchange in regeneration unit 4, the medium-temperature gas (80~150℃) enters the heating section of pyrolysis unit 2, and the temperature of pyrolysis unit 2 is controlled between 40℃ and 80℃. After heat exchange in pyrolysis unit 2, the ambient-temperature gas enters the decarbonization reactor through the inlet 1-2 of the decarbonization reactor, and the temperature of the solution in the decarbonization reactor is controlled not to exceed 30℃.

[0044] In one embodiment, the slag outlet 1-4 of the decarbonization reactor is located at the lowest point of the reactor. The gas inlet 1-2 of the decarbonization reactor is below the surface of the alkaline solution, and the gas outlet 1-3 is above the surface of the alkaline solution. This structure forces the gas to travel through the longest liquid path, avoiding potential short-circuiting of the gas within the decarbonization reactor, where the gas flows directly from the inlet to the outlet without sufficient contact with the liquid. This ensures that the carbon dioxide in the gas has sufficient contact with the alkaline solution.

[0045] The inlet 3-2 of the deammoniation reactor is located at the bottom of the moving bed of the electrophilic reagent packing. This promotes sufficient contact between the mixed gas and the electrophilic reagent particles.

[0046] In one embodiment, the alkaline solution is ammonia water, the generated acidic carbonate is ammonium bicarbonate, the alkaline gas in the aqueous solution is ammonia, the electrophilic reagent is anhydrous cobalt chloride particles or anhydrous calcium chloride particles, preferably anhydrous calcium chloride particles, and the coordination compound is calcium chloride-ammonia compound.

[0047] Specifically, ammonia is chosen as the alkaline solution, and the acidic carbonate formed by absorbing carbon dioxide is ammonium bicarbonate, with the reaction formula: NH3•H2O + CO2 == NH4HCO3. Since solid ammonium bicarbonate begins to decompose above 30℃, decomposition accelerates at 40℃, and complete decomposition occurs at 60℃, the reaction of ammonia absorbing carbon dioxide in decarbonation unit 1 must be controlled at a relatively low temperature (≤30℃). Therefore, the temperature of the solution inside the decarbonation reactor should be kept below 30℃, ideally between 10~20℃. Too low a temperature will result in a lower reaction rate, requiring the gas to remain in decarbonation unit 1 for a longer period to ensure sufficient carbon dioxide absorption.

[0048] Because ammonia has a very high solubility in water, while ammonium bicarbonate has a relatively low solubility, ammonium bicarbonate crystals can be obtained by absorbing carbon dioxide with concentrated ammonia solution. The ammonium bicarbonate crystals are collected, drained, and transported to thermal decomposition unit 2. By increasing the temperature, the ammonium bicarbonate decomposes into ammonia, water, and carbon dioxide. The reaction formula is: NH₄HCO₃ NH3↑ + H2O + CO2↑. To decompose ammonium bicarbonate into ammonia, carbon dioxide, and liquid water, the thermal decomposition unit 2 needs to be temperature-controlled between 40℃ and 80℃.

[0049] The ammonia and carbon dioxide mixture generated by thermal decomposition is transported to the deammoniation unit 3 via pipeline through the exhaust port 2-3 of the thermal decomposition unit. In the deammoniation unit 3, the mixed gas comes into full contact with anhydrous calcium chloride particles, and the ammonia in it undergoes a coordination reaction (also called a complexation reaction) with the calcium chloride to form ammonium compounds containing different numbers of ammonia molecules, namely calcium chloride-ammonium compounds. Among them, the octaammonium compound is the most common stable form, and its reaction formula is: CaCl2 + 8NH3 === CaCl2•8NH3.

[0050] Within regeneration unit 4, calcium chloride particles saturated with ammonia release complexed ammonia molecules upon heating. The number of released ammonia molecules varies depending on the temperature gradient. At lower temperatures (approximately 88°C), some ammonia molecules (e.g., two NH3 ions) are released; at medium to high temperatures (above 106°C), the remaining ammonia molecules are gradually desorbed; and complete regeneration is achieved only at even higher temperatures (e.g., 250°C). Therefore, the temperature within regeneration unit 4 needs to be controlled at 250°C or higher. The released ammonia is piped to the inlet of decarbonization unit 1, while the remaining calcium chloride particles are returned to deammoniation unit 3 to reabsorb ammonia.

[0051] Furthermore, considering the operating conditions of decarbonization unit 1, pyrolysis unit, deammoniation unit 3, and regeneration unit 4, most of the entire system (except regeneration unit 4) operates at relatively low temperatures (below 100℃) and under slightly alkaline conditions. Therefore, the main materials of the equipment in the system can be common plastics, such as thermosetting phenolic resin, polytetrafluoroethylene, and rigid polyethylene (UPVC). Specifically, decarbonization unit 1 and deammoniation unit 3 operate under relatively mild conditions, with the solution or atmosphere having a certain degree of alkalinity. These two units can be constructed and connected using UPVC tanks and pipelines. The highest temperature of pyrolysis unit 2 is no more than 100℃, and it is made of heat-resistant resin material, except that the internal heat exchange baffles are made of cast iron, which has better thermal conductivity. Regeneration unit 4, which operates at a relatively higher temperature, is made of cast iron.

[0052] This system was used to upgrade different types of underground gasified coal gas. The composition of the coal gas before and after upgrading is shown in Tables 1 and 2 below. It can be seen that the system has a good effect on removing carbon dioxide from the coal gas. Compared with the change in component content before and after upgrading air-gasified coal gas, this system has a better effect on upgrading oxygen-enriched carbon dioxide gasified coal gas.

[0053] Table 1 Comparison of air-to-ground gasification gas quality before and after upgrading Before quality improvement 20.60 17.85 11.76 2.61 47.22 0.00 32.22 4.35 After quality improvement 0.00 21.14 13.93 3.05 61.92 0.02 38.06 5.12

[0054] Table 2 Comparison of Oxygen-Enriched Carbon Dioxide Underground Gasification Gas Before and After Upgrading Before quality improvement 59.76 25.30 13.70 1.20 0.04 0.00 40.20 4.89 After quality improvement 2.01 61.87 32.85 2.98 0.12 0.05 97.7 11.88

[0055] By adopting the above technical solution, the underground gasification gas can be separated into carbon dioxide and high-quality gas with effective components through low temperature, low energy consumption, and simple equipment by recycling materials within the system. Furthermore, the thermal energy carried by the gas can be utilized in a cascade manner.

[0056] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An underground gasification gas upgrading system, characterized in that, include: The decarbonization unit includes a decarbonization reactor containing an alkaline solution. The inlet of the decarbonization reactor is connected to the outlet pipeline of the pre-upgrading coal gas. The gas discharged from the outlet of the decarbonization reactor is the upgraded coal gas. The alkaline solution absorbs the carbon dioxide in the pre-upgrading coal gas and generates acidic carbonates which are discharged through the slag outlet of the decarbonization reactor. The thermal decomposition unit is used to thermally decompose acidic carbonates to generate a mixture of gas and carbon dioxide in an aqueous solution. The mixture is discharged through the exhaust port of the thermal decomposition unit. The deammoniation unit includes a deammoniation reactor containing an electrophilic reagent. The inlet of the deammoniation reactor is connected to the outlet of the pyrolysis unit. The electrophilic reagent separates carbon dioxide from the mixed gas and generates a coordination compound, which is discharged through the outlet of the deammoniation reactor. The regeneration unit thermally decomposes the coordination compound to generate an alkaline gas and an electrophilic reagent in aqueous solution. The gas is then transported to the decarbonization unit, and the electrophilic reagent is transported to the deammoniation unit.

2. The underground gasification gas upgrading system according to claim 1, characterized in that, The upper end of the decarbonization reactor is provided with an inlet pipe that is connected to an external liquid supply pipeline. Inside the decarbonization reactor, there is a spray component that is connected to the inlet pipe. The spray component allows the alkaline solution to be sprayed and come into countercurrent contact with the coal gas.

3. The underground gasification gas upgrading system according to claim 1 or 2, characterized in that, The decarbonization reactor is equipped with a gas distribution plate, the gas inlet of which is connected to the gas inlet of the decarbonization reactor, and the gas distribution plate disperses the coal gas into the alkaline solution.

4. The underground gasification gas upgrading system according to claim 1, characterized in that, Both the pyrolysis unit and the regeneration unit are equipped with heating sections. The heating sections are partitioned heat exchange structures, and the heat source is the gas from the outlet of the underground gasifier. The gas from the outlet of the underground gasifier first undergoes heat exchange in the heating section of the regeneration unit, and then is transported through pipelines to the heating section of the pyrolysis unit for further heat exchange.

5. The underground gasification gas upgrading system according to claim 1, characterized in that, The feed inlet of the deammoniation reactor is located at the top of the reactor, and the discharge inlet is located at the bottom. A funnel-shaped gas distribution plate with multiple vent holes is installed inside the reactor. The gas distribution plate divides the inner cavity of the deammoniation reactor into upper and lower chambers. The electrophilic reagent is placed in the upper chamber. The lowest point of the gas distribution plate is connected to the discharge inlet of the deammoniation reactor. The gas inlet of the deammoniation reactor is located in the middle of the lower chamber, and the gas outlet is located in the upper-middle part of the upper chamber.

6. The underground gasification gas upgrading system according to claim 1, characterized in that, The carbon dioxide separated in the deammoniation unit is discharged through the outlet of the deammoniation reactor. The inlet of the decarbonization reactor is below the surface of the alkaline solution, and the outlet of the decarbonization reactor is above the surface of the alkaline solution.

7. The underground gasification gas upgrading system according to claim 1, characterized in that, The decarbonization reactor is equipped with a first temperature measuring element for monitoring the temperature of the solution inside the container and a pH monitoring element for monitoring the pH value of the solution inside the container.

8. The underground gasification gas upgrading system according to claim 1, characterized in that, The thermal decomposition unit is equipped with a second temperature measuring element for monitoring the reaction temperature, and the regeneration unit is equipped with a third temperature measuring element for monitoring the reaction temperature.

9. The underground gasification gas upgrading system according to claim 1, characterized in that, The alkaline solution is ammonia water, the generated acidic carbonate is ammonium bicarbonate, the alkaline gas in the aqueous solution is ammonia, the electrophilic reagent is anhydrous calcium chloride particles, and the coordination compound is calcium chloride-ammonia compound.

10. The underground gasification gas upgrading system according to claim 1, characterized in that, The feed inlet of the pyrolysis unit is connected to the slag outlet of the decarbonization reactor; the feed inlet of the regeneration unit is connected to the discharge outlet of the deammoniation reactor.

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