Method and device for in-situ utilization of carbon dioxide in underground coal gasification

Abstract

The application provides a coal underground gasification carbon dioxide in-situ utilization method and device, wherein the method controls oxygen injection into coal in a to-be-mined area to introduce a first reaction parameter; when the first reaction parameter reaches a first preset value, the method controls continuous oxygen injection into the coal in the to-be-mined area and injection of water vapor and hydrogen to introduce a second reaction parameter; when the second reaction parameter reaches a second preset value, the method controls the stop of water vapor and hydrogen injection and controls carbon dioxide re-injection into the coal in the to-be-mined area to introduce a third reaction parameter; when the third reaction parameter reaches a third preset value, the method controls the stop of carbon dioxide re-injection into the coal in the to-be-mined area and controls oxygen injection into the coal in the to-be-mined area, and the above process is repeated. The method controls carbon dioxide obtained through reaction to be re-injected into the coal in the to-be-mined area, carbon monoxide is obtained through reaction, carbon dioxide emission is reduced, and carbon dioxide storage and transportation costs are reduced.

Description

Technical Field

[0001] This invention relates to the field of underground coal gasification technology, and in particular to a method and apparatus for in-situ utilization of carbon dioxide from underground coal gasification. Background Technology

[0002] Underground coal gasification technology utilizes the chemical properties of coal to control the combustion of coal seams in their original geographical environment. The process produces combustible gases through the chemical combustion of coal and the thermal effects of the coal seams. The entire process is carried out in a pre-built underground gasification chamber, and carbon-based resources are collected on the surface in the form of gases such as CH4, CO, and CO2. Current underground coal gasification processes consist of two stages: the first stage involves blowing air into the gas supply port to provide the heat energy for the entire gasification reaction, also known as the heat storage stage. This stage produces low-calorific-value coal gas (with a production calorific value of 4.18 MJ / m³). 3 The first stage (approximately 1.56 MJ / m³) can be used as industrial fuel or for power generation; the second stage involves blowing steam into the gas supply port to produce high-calorific-value gas (with a calorific value of 12.56 MJ / m³). 3 (Approximately 100 meters), which can be used as a source of electricity for urban residential use. Summary of the Invention

[0003] The applicant of this invention has discovered that existing underground coal gasification technologies either directly release the produced carbon dioxide to the surface or directly into the atmosphere, which increases the atmospheric carbon dioxide content and fails to meet national requirements for reducing carbon dioxide emissions. Alternatively, the carbon dioxide is stored and transported to chemical plants or storage sites for unified sealing, resulting in high carbon dioxide storage and transportation costs. Consequently, the cost of underground coal gasification technology remains high, making it difficult to promote its widespread use.

[0004] In view of the above problems, it is necessary to propose a method for in-situ utilization of carbon dioxide from underground coal gasification to solve or partially solve these problems. The technical solution proposed by this invention is as follows:

[0005] In a first aspect, the present invention proposes a method for in-situ utilization of carbon dioxide from underground coal gasification, comprising:

[0006] Oxygen is injected into the coal in the mining area to carry out coal combustion and pyrolysis reactions to obtain the first reaction product. The oxygen intake is controlled and detected, as well as the carbon dioxide production and oxygen overflow in the first reaction product, and the first reaction criterion is calculated.

[0007] Determine whether the first reaction threshold has reached the first preset value. If so, control the continuous injection of oxygen into the coal in the mining area, and inject water vapor and hydrogen to react and obtain the second reaction product. Control and detect the amount of water vapor injected, as well as the amount of carbon monoxide and hydrogen produced in the second reaction product, and calculate the second reaction threshold.

[0008] Determine whether the second reaction threshold has reached the second preset value. If so, control the stopping of water vapor and hydrogen injection, and control the reinjection of carbon dioxide from the first reaction product and the second reaction product into the coal in the mining area to react and obtain carbon monoxide. Control the detection of the amount of carbon dioxide injected into the coal in the mining area and the amount of carbon dioxide overflow of the remaining carbon dioxide, and calculate the third reaction threshold.

[0009] Determine whether the third reaction standard has reached the third preset value. If so, control the stopping of carbon dioxide reinjection into the coal in the mining area and control the injection of oxygen into the coal in the mining area, repeating the above process to obtain the first reaction product, the second reaction product and carbon monoxide.

[0010] Furthermore, the first reaction coefficient S I =V1 / (V2-V3), where V1 is the amount of carbon dioxide produced, V2 is the amount of oxygen introduced, and V3 is the amount of oxygen released.

[0011] Furthermore, the second reaction coefficient S II = (V5+V6) / V4, where V4 is the amount of water vapor injected, V5 is the amount of carbon monoxide produced, and V6 is the amount of hydrogen produced.

[0012] Furthermore, the third reaction criterion S III = (V7-V8) / V7, where V7 is the amount of carbon dioxide injected and V8 is the amount of carbon dioxide overflowed.

[0013] Furthermore, after the reaction to obtain carbon monoxide, the process further includes:

[0014] The hydrogen gas and the remaining carbon dioxide in the second reaction product are controlled to react to obtain methanol.

[0015] Furthermore, the control of reacting the hydrogen and remaining carbon dioxide in the second reaction product to obtain methanol further includes: controlling and detecting the initial carbon dioxide injection amount V9 before the reaction and the remaining carbon dioxide overflow amount V after the reaction. 10 And calculate the carbon dioxide conversion rate, wherein the carbon dioxide conversion rate X = (V9 - V) 10 ) / V9×100%, where V9 is the initial amount of carbon dioxide injected, V 10 This represents the amount of carbon dioxide released.

[0016] Furthermore, after controlling the reaction of hydrogen and residual carbon dioxide in the second reaction product to obtain methanol, the method further includes: controlling the metering of methanol production W1 and calculating the methanol yield Y1 = 0.7W1 / (V9 - V 10 )×100%.

[0017] Furthermore, after controlling the reaction of the hydrogen and the remaining carbon dioxide in the second reaction product to obtain methanol, the method further includes controlling the methanol to undergo a methanol-to-olefins reaction to obtain ethylene and propylene.

[0018] Furthermore, after controlling the methanol-to-olefins device to produce ethylene and propylene by methanol-to-olefins reaction, the method further includes: controlling the product metering device to measure the ethylene yield W2 and propylene yield W3, and calculating the ethylene yield Y2 and propylene yield Y3, where Y2 = 2.29W2 / W1 × 100% and Y3 = 2.29W3 / W1 × 100%.

[0019] Secondly, the present invention also proposes an underground coal gasification carbon dioxide in-situ utilization device, comprising: a first module, a second module, a third module, and a fourth module, wherein:

[0020] The first module is used to control the injection of oxygen into the coal in the mining area to carry out coal combustion reaction and coal pyrolysis reaction to obtain the first reaction product, control and detect the oxygen intake of the injected oxygen, as well as the carbon dioxide production and oxygen overflow in the first reaction product, and calculate the first reaction criterion.

[0021] The second module is used to determine whether the first reaction threshold has reached the first preset value. If so, it controls the continuous injection of oxygen into the coal in the mining area, and injects water vapor and hydrogen to react and obtain the second reaction product. It controls the detection of the water vapor injection amount, as well as the carbon monoxide production amount and hydrogen production amount in the second reaction product, and calculates the second reaction threshold.

[0022] The third module is used to determine whether the second reaction threshold has reached the second preset value. If so, it controls the stopping of the injection of water vapor and hydrogen, and controls the reinjection of carbon dioxide from the first reaction product and the second reaction product into the coal in the mining area to react and obtain carbon monoxide. It controls the detection of the amount of carbon dioxide injected into the coal in the mining area and the amount of carbon dioxide overflow of the remaining carbon dioxide, and calculates the third reaction threshold.

[0023] The fourth module is used to determine whether the third reaction standard has reached the third preset value. If so, it controls the stopping of carbon dioxide reinjection into the coal in the mining area and controls the injection of oxygen into the coal in the mining area, repeating the above process to obtain the first reaction product, the second reaction product and carbon monoxide.

[0024] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0025] The present invention proposes a method for in-situ utilization of carbon dioxide from underground coal gasification. This method involves controlling the reinjection of the carbon dioxide obtained from the reaction into the coal in the area to be mined, where it reacts to produce carbon monoxide, which has combustion value. This increases the effective calorific value of the produced gas while reducing carbon dioxide emissions and lowering carbon dioxide storage and transportation costs. Furthermore, the reaction between coal and carbon dioxide to produce carbon monoxide is an endothermic reaction; the reinjection of carbon dioxide lowers the temperature to some extent, reducing water and energy costs associated with steam cooling. The carbon dioxide reinjection process generates a significant impact force, which can penetrate the coal seam and ash layer a second time, increasing the effective carbon reaction surface area and thus improving the utilization rate of deep coal resources. Attached Figure Description

[0026] Figure 1 This is a schematic flowchart of the method for in-situ utilization of carbon dioxide from underground coal gasification in an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the structure of the first underground coal gasification reaction in an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the second stage of underground coal gasification reaction in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the third stage of underground coal gasification reaction in an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] This invention provides a method for in-situ utilization of carbon dioxide from underground coal gasification, comprising:

[0032] Step S101: Control the injection of oxygen into the coal in the area to be mined to carry out coal combustion reaction and coal pyrolysis reaction to obtain the first reaction product. Control and detect the oxygen intake of the injected oxygen, as well as the carbon dioxide production and oxygen overflow in the first reaction product, and calculate the first reaction criterion.

[0033] In this step, the first reaction criterion S I =V1 / (V2-V3)(1); where V1 is the carbon dioxide production, V2 is the oxygen intake, and V3 is the oxygen overflow.

[0034] Step S102: Determine whether the first reaction standard has reached the first preset value. If so, control the continuous injection of oxygen into the coal in the mining area, and inject water vapor and hydrogen to react and obtain the second reaction product. Control the detection of the water vapor injection amount, as well as the carbon monoxide production amount and hydrogen production amount in the second reaction product, and calculate the second reaction standard.

[0035] In this step, the second reaction coefficient S II = (V5+V6) / V4, where V4 is the amount of water vapor injected, V5 is the amount of carbon monoxide produced, and V6 is the amount of hydrogen produced.

[0036] Step S103: Determine whether the second reaction threshold has reached the second preset value. If so, control the stopping of water vapor and hydrogen injection, and control the reinjection of carbon dioxide from the first reaction product and the second reaction product into the coal in the mining area to react and obtain carbon monoxide. Control the detection of the amount of carbon dioxide injected into the coal in the mining area and the amount of carbon dioxide overflow of the remaining carbon dioxide, and calculate the third reaction threshold.

[0037] In this step, the third reaction criterion S III = (V7-V8) / V7, where V7 is the amount of carbon dioxide injected and V8 is the amount of carbon dioxide overflowed.

[0038] Step S104: Determine whether the third reaction standard has reached the third preset value. If so, control the stopping of carbon dioxide reinjection into the coal in the mining area and control the injection of oxygen into the coal in the mining area, repeating the above process to obtain the first reaction product, the second reaction product and carbon monoxide.

[0039] Specifically, such as Figure 2 As shown, the first stage of the injection process involves injecting oxygen-enriched air or pure oxygen through the inlet of the annular bushing for ignition via chemical combustion. This stage primarily involves coal pyrolysis and combustion reactions, i.e., the creation of the gasification chamber, and provides heat for the second and third stages of underground coal gasification reactions. The main chemical reactions occurring in the first stage include:

[0040] ①C + O₂ → CO₂;

[0041] ②2C + O2 → 2CO;

[0042] ③ Coal → CO + CO2 + CH4 + N2 + H2O.

[0043] Reactions ① and ② mainly occur near the ignition point; reaction ③ mainly occurs in the coal seam, where the oxygen concentration is relatively low. Coal pyrolysis occurs through heat transfer, and the produced gas is released into the gasification chamber through mass transfer in the opposite direction of heat transfer. After secondary combustion in the combustion zone, it is transported to the output port.

[0044] like Figure 3 As shown, the second-stage injection process: Once the first-stage vaporization chamber has initially reached a certain scale, O2 is continuously injected, and water vapor is blown in through the annular sleeve to provide a hydrogen source, generating high-calorific-value vaporization products such as H2 and CH4. The main chemical reactions occurring within the vaporization chamber include:

[0045] ④C + H₂O → CO + H₂;

[0046] ⑤C + 2H₂ → CH₄;

[0047] ⑥CO + H₂O → CO₂ + H₂;

[0048] ⑦CO + 3H2 → CH4 + H2O.

[0049] In the second stage, water vapor absorbs some heat, and the temperature of the coal seam and gas flow begins to decrease. Reactions occur between the coal seam and the boundary layer of the gasification chamber (④, ⑤); homogeneous gasification reactions can occur in the gasification chamber because no oxygen is involved (⑥, ⑦).

[0050] like Figure 4 As shown, the third stage of the injection process: As can be seen from the above, a large amount of CO2 will be generated in reactions ①, ③, and ⑥. The CO2 is separated by methanol washing or membrane separation and then reinjected into the intake well via a short-distance stainless steel CO2 pipeline for CO2 reinjection. The Boudouard reaction mainly occurs within the vaporization chamber.

[0051] ⑧C + CO2 → 2CO.

[0052] The present invention proposes a method for in-situ utilization of carbon dioxide from underground coal gasification. This method involves controlling the reinjection of the carbon dioxide obtained from the reaction into the coal in the area to be mined, where it reacts to produce carbon monoxide, which has combustion value. This increases the effective calorific value of the produced gas while reducing carbon dioxide emissions and lowering carbon dioxide storage and transportation costs. Furthermore, the reaction between coal and carbon dioxide to produce carbon monoxide is an endothermic reaction; the reinjection of carbon dioxide lowers the temperature to some extent, reducing water and energy costs associated with steam cooling. The carbon dioxide reinjection process generates a significant impact force, which can penetrate the coal seam and ash layer a second time, increasing the effective carbon reaction surface area and thus improving the utilization rate of deep coal resources.

[0053] In one embodiment, after the reaction to obtain carbon monoxide in step S103, the method further includes: controlling the reaction of hydrogen and the remaining carbon dioxide in the second reaction product to obtain methanol.

[0054] In this embodiment, since the crude coal gas produced by traditional underground coal gasification technology mainly contains four gases: H2, CO, CO2, and CH4, it needs to be transported to chemical plants or power plants through processes such as separation, collection, and storage. The carbon dioxide treatment module converts carbon dioxide and hydrogen into methanol, which is easy to store and transport, thereby reducing the bottling and transportation costs of CO2 and H2 and improving economic efficiency.

[0055] In a further embodiment, after controlling the reaction of hydrogen and residual carbon dioxide in the second reaction product to obtain methanol, the method further includes: controlling and detecting the initial carbon dioxide injection amount V9 before the reaction and the residual carbon dioxide overflow amount V after the reaction. 10 And calculate the carbon dioxide conversion rate;

[0056] The carbon dioxide conversion rate X = (V9 - V) 10 ) / V9×100%(4); where V9 is the initial amount of carbon dioxide injected, V 10 This represents the amount of carbon dioxide released.

[0057] In this embodiment, the hydrogen in the second reaction product and the remaining carbon dioxide are reacted to obtain methanol, and the CO2 conversion rate can reach 20-50%, which can significantly reduce the volume of the CO2 buffer tank and realize the full-process circulation of CO2.

[0058] In a further embodiment, after controlling the reaction of hydrogen and the remaining carbon dioxide in the second reaction product to obtain methanol, the method further includes: controlling the metering of methanol production W1 and calculating the methanol yield.

[0059] The methanol yield Y1 = 0.7W1 / (V9-V 10 )×100%(5); where W1 is the methanol production.

[0060] In a further embodiment, after controlling the reaction of hydrogen and the remaining carbon dioxide in the second reaction product to obtain methanol, the method further includes controlling the methanol to undergo a methanol-to-olefins reaction to obtain ethylene and propylene.

[0061] In a further embodiment, after controlling the methanol-to-olefins device to produce ethylene and propylene by methanol-to-olefins reaction, the method further includes: controlling the product metering device to meter the ethylene yield W2 and the propylene yield W3, and calculating the ethylene yield Y2 and the propylene yield Y3.

[0062] Y2=2.29W2 / W1×100%(6); where W1 is the methanol production and W2 is the ethylene production;

[0063] Y3=2.29W3 / W1×100%(7); where W1 is the methanol production and W3 is the propylene production.

[0064] Example 1

[0065] Along the annular sleeve at 300m 3 Pure oxygen is injected at a rate of / h, and underground coal is ignited by gunpowder and combustion aid, providing heat energy for the subsequent two stages of reaction and creating a gasification chamber. The input O2 flow rate V2, output O2 overflow rate V3, and CO2 production rate V1 of the first stage underground coal gasification reaction are monitored in real time. Calculated using formula (1), when the first reaction coefficient S... I When the value is 0.7, enter the "Terminate First Segment" command and click the "Start Second Segment" command. At this time, the data feedback for the first segment S... I =0.78, and the results are shown in Table 1.

[0066] Example 1 300 45 198 0.78 Example 2 1000 229 648 0.84 Example 3 1500 377 1098 0.97

[0067] Table 1

[0068] After the first stage oxygen injection command is terminated, water vapor is injected under continuous O2 injection operation, maintaining a water vapor injection volume to vaporizing agent volume ratio of 30%, and a water vapor injection rate of 300 m / s. 3 / h. Real-time monitoring of the H2O injection rate V4, CO production rate V5, H2 production rate V6, CH4 production rate, and CO2 production rate at the input port of the second-stage underground coal gasification reaction. Calculated using formula (2), when the second reaction coefficient S II When the value is 0.7, enter the "Second Segment Terminate" command and click the "Third Segment Start" command. At this time, the data feedback for the second segment S... II =0.77, and the results are shown in Table 2.

[0069] Example 1 300 120 110 173 0.77 Example 2 2000 880 560 956 0.72 Example 3 3000 1691 398 725 0.70

[0070] Table 2

[0071] In the initial stage of the third phase, the CO2 generated in the first and second phases is transported from the outlet to the inlet through pipelines and reinjected into the gasification chamber. The CO2 injection rate V7 and the CO2 overflow rate V8 from the outlet are monitored in real time. Using formula (3), when the third reaction coefficient S... III When the value is 0.7, enter the "Terminate Third Segment" command and click the "Start First Segment" command to start the next cycle. At this time, the data feedback for the third segment S... III =0.76, and the results are shown in Table 3. Table 3 shows that the effective CO2 treatment capacity can be increased to over 70% (S). III >0.7), which can significantly reduce CO2 emissions.

[0072]

[0073]

[0074] Table 3

[0075] The gas overflowing after being circulated through the "three-stage underground coal gasification" process will be released at a velocity of 41m. 3 The methanol is delivered to the ground at a rate of / h, and the CO2 processing module is activated to obtain methanol. The initial carbon dioxide injection volume V9 and the carbon dioxide overflow volume V from the carbon dioxide processing module are recorded. 10 With methanol production W1, the carbon dioxide conversion rate X is calculated using formula (4), and the methanol production Y1 is calculated using formula (5). The methanol-to-hydrocarbon module is started to obtain ethylene and propylene. The ethylene production W2 and propylene production W3 are recorded. The ethylene yield Y2 is calculated using formula (6), and the propylene yield Y3 is calculated using formula (7), as shown in Table 4. As can be seen from Table 4, the yields of methanol, ethylene, and propylene, as well as the CO2 conversion rate, are all higher than 92%, which can significantly reduce the volume of the CO2 buffer tank and realize the full-process circulation of CO2.

[0076]

[0077] Table 4

[0078] Example 2

[0079] Along the annular sleeve at 1000m 3 Pure oxygen is injected at a rate of / h, and underground coal is ignited by gunpowder and combustion aid, providing heat energy for the subsequent two stages of reaction and creating a gasification chamber. The input O2 flow rate V2, output O2 overflow rate V3, and CO2 production rate V1 of the first stage underground coal gasification reaction are monitored in real time. Calculated using formula (1), when the first reaction coefficient S... I When the value is 0.7, enter the "Terminate First Segment" command and click the "Start Second Segment" command. At this time, the data feedback first reaction accuracy S will be displayed. I =0.84, and the results are shown in Table 1.

[0080] After the first stage oxygen injection command is terminated, water vapor (H2O(g)) is injected under continuous O2 injection operation, maintaining the ratio of water vapor injection volume to gasifying agent volume at 30%, and the water vapor injection rate at 2000 m / s². 3 / h. Real-time monitoring of the H2O injection rate V4, CO gas production rate V5, H2 gas production rate V6, CH4 gas production rate, and CO2 gas production rate at the input port of the second stage underground coal reaction. Calculated using formula (2), when the second reaction coefficient S II When the value is 0.7, enter the "Second Segment Terminate" command and click the "Third Segment Start" command. At this time, the data feedback second reaction standard S will be displayed. II =0.72, and the results are shown in Table 2.

[0081] In the initial stage of the third phase, the CO2 generated in the second phase is transported from the outlet to the inlet through a pipeline and reinjected into the gasification chamber. The CO2 injection rate V7 and the CO2 overflow rate V8 from the outlet are monitored in real time. Using formula (3), when the third reaction coefficient S... III When the value is 0.7, enter the "Terminate Third Segment" command and click the "Start First Segment" command to start the next cycle. At this time, the data feedback will show the third reaction standard S. III =0.91, and the results are shown in Table 3. Table 3 shows that the effective CO2 treatment capacity can be increased to over 70% (S). III >0.7), which can significantly reduce CO2 emissions.

[0082] The gas overflowing after being circulated through the "three-stage underground coal gasification" process will be released at 86m 3 The methanol is delivered to the ground at a rate of / h, and the CO2 processing module is activated to obtain methanol. The initial carbon dioxide injection volume V9 and the carbon dioxide overflow volume V from the carbon dioxide processing module are recorded. 10 With methanol production W1, the carbon dioxide conversion rate X is calculated using formula (4), and the methanol production Y1 is calculated using formula (5). The methanol-to-hydrocarbon module is started to obtain ethylene and propylene. The ethylene production W2 and propylene production W3 are recorded. The ethylene yield Y2 is calculated using formula (6), and the propylene yield Y3 is calculated using formula (7), as shown in Table 4. As can be seen from Table 4, the yields of methanol, ethylene, and propylene, as well as the CO2 conversion rate, are all higher than 92%, which can significantly reduce the volume of the CO2 buffer tank and realize the full-process circulation of CO2.

[0083] Example 3

[0084] Along the annular bushing at 1500m 3 Pure oxygen is injected at a rate of / h, and underground coal is ignited by gunpowder and combustion aid, providing heat energy for the subsequent two stages of reaction and creating a gasification chamber. The input O2 flow rate V2, output O2 overflow rate V3, and CO2 production rate V1 of the first stage underground coal gasification reaction are monitored in real time. Calculated using formula (1), when the first reaction coefficient S... I When the value is 0.7, enter the "Terminate First Segment" command and click the "Start Second Segment" command. At this time, the data feedback first reaction accuracy S will be displayed. I =0.97, and the results are shown in Table 1.

[0085] After the first stage of oxygen injection is terminated, water vapor is injected under continuous O2 injection operation, maintaining a water vapor injection volume fraction to vaporizing agent volume ratio of 30%, and a water vapor injection rate of 3000 m / s. 3 / h. Real-time monitoring of the H2O injection rate V4, CO gas production rate V5, H2 gas production rate V6, CH4 gas production rate, and CO2 gas production rate at the input port of the second stage underground coal reaction. Calculated using formula (2), when the second reaction coefficient S II When the value is 0.7, enter the "Second Segment Terminate" command and click the "Third Segment Start" command. At this time, the data feedback second reaction standard S will be displayed. II =0.70, and the results are shown in Table 2.

[0086] In the initial stage of the third phase, the CO2 generated in the second phase is transported to the outlet through pipeline and reinjected through the injection end. The CO2 injection rate V7 and the CO2 overflow rate V8 at the outlet are monitored in real time. The third reaction criterion S is calculated using formula (3). III When the value is 0.7, enter the "Terminate Third Segment" command and click the "Start First Segment" command to start the next cycle. At this time, the data feedback will show the third reaction standard S. III =0.80, and the results are shown in Table 3. Table 3 shows that the effective CO2 treatment capacity can be increased to over 70% (S). III >0.7), which can significantly reduce CO2 emissions.

[0087] The gas overflowing after being circulated through the "three-stage underground coal gasification" process will be released at a velocity of 142m. 3 The methanol is delivered to the ground at a rate of / h, and the CO2 processing module is activated to obtain methanol. The initial carbon dioxide injection volume V9 and the carbon dioxide overflow volume V from the carbon dioxide processing module are recorded. 10 With methanol production W1, the carbon dioxide conversion rate X is calculated using formula (4), and the methanol production Y1 is calculated using formula (5). The methanol-to-hydrocarbon module is started to obtain ethylene and propylene. The ethylene production W2 and propylene production W3 are recorded. The ethylene yield Y2 is calculated using formula (6), and the propylene yield Y3 is calculated using formula (7), as shown in Table 4. As can be seen from Table 4, the yields of methanol, ethylene, and propylene, as well as the CO2 conversion rate, are all higher than 92%, which can significantly reduce the volume of the CO2 buffer tank and realize the full-process circulation of CO2.

[0088] Based on the same inventive concept, this invention also proposes an underground coal gasification carbon dioxide in-situ utilization device, comprising: a first module, a second module, a third module, and a fourth module, wherein:

[0089] The first module is used to control the injection of oxygen into the coal in the mining area to carry out coal combustion reaction and coal pyrolysis reaction to obtain the first reaction product, control and detect the oxygen intake of the injected oxygen, as well as the carbon dioxide production and oxygen overflow in the first reaction product, and calculate the first reaction criterion.

[0090] The second module is used to determine whether the first reaction threshold has reached the first preset value. If so, it controls the continuous injection of oxygen into the coal in the mining area, and injects water vapor and hydrogen to react and obtain the second reaction product. It controls the detection of the water vapor injection amount, as well as the carbon monoxide production amount and hydrogen production amount in the second reaction product, and calculates the second reaction threshold.

[0091] The third module is used to determine whether the second reaction threshold has reached the second preset value. If so, it controls the stopping of the injection of water vapor and hydrogen, and controls the reinjection of carbon dioxide from the first reaction product and the second reaction product into the coal in the mining area to react and obtain carbon monoxide. It controls the detection of the amount of carbon dioxide injected into the coal in the mining area and the amount of carbon dioxide overflow of the remaining carbon dioxide, and calculates the third reaction threshold.

[0092] The fourth module is used to determine whether the third reaction standard has reached the third preset value. If so, it controls the stopping of carbon dioxide reinjection into the coal in the mining area and controls the injection of oxygen into the coal in the mining area, repeating the above process to obtain the first reaction product, the second reaction product and carbon monoxide.

[0093] This invention also proposes an underground coal gasification carbon dioxide in-situ utilization device. The carbon dioxide obtained from the reaction is reinjected into the coal in the mining area to produce carbon monoxide, which has combustion value. This can increase the effective calorific value of the produced gas, reduce carbon dioxide emissions, and lower the cost of carbon dioxide storage and transportation. In addition, the reaction between coal and carbon dioxide to produce carbon monoxide is an endothermic reaction. The carbon dioxide reinjection reduces the temperature to a certain extent, reducing the water and energy costs caused by water vapor cooling. The carbon dioxide reinjection process generates a huge impact force, which can penetrate the coal seam and coal ash layer a second time, increasing the effective carbon reaction surface area and improving the utilization rate of deep coal resources.

[0094] In one embodiment, the third module is further configured to, after reacting to obtain carbon monoxide, control the reaction of hydrogen in the second reaction product with the remaining carbon dioxide to obtain methanol.

[0095] In one embodiment, the third module is further configured to control the methanol to olefins reaction to produce ethylene and propylene.

[0096] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0097] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A method for in-situ utilization of carbon dioxide from underground coal gasification, characterized in that, include: Oxygen is injected into the coal in the mining area to carry out coal combustion and pyrolysis reactions to obtain the first reaction product. The oxygen intake is controlled and detected, as well as the carbon dioxide production and oxygen overflow in the first reaction product, and the first reaction criterion is calculated. The first reaction coefficient S I = V1 / ( V2-V3), where V1 is the carbon dioxide production, V2 is the oxygen intake, and V3 is the oxygen overflow. Determine whether the first reaction threshold has reached the first preset value. If so, control the continuous injection of oxygen into the coal in the mining area, and inject water vapor and hydrogen to react and obtain the second reaction product. Control and detect the amount of water vapor injected, as well as the amount of carbon monoxide and hydrogen produced in the second reaction product, and calculate the second reaction threshold. The second reaction coefficient S II =(V5+V6) / V4, where V4 is the amount of water vapor injected, V5 is the amount of carbon monoxide produced, and V6 is the amount of hydrogen produced; Determine whether the second reaction threshold has reached the second preset value. If so, control the stopping of water vapor and hydrogen injection, and control the reinjection of carbon dioxide from the first reaction product and the second reaction product into the coal in the mining area to react and obtain carbon monoxide. Control the detection of the amount of carbon dioxide injected into the coal in the mining area and the amount of remaining carbon dioxide overflow, and calculate the third reaction threshold. The third reaction coefficient S III =( V7 - V8) / V7, where V7 is the amount of carbon dioxide injected and V8 is the amount of carbon dioxide overflowed; Determine whether the third reaction standard has reached the third preset value. If so, control the stopping of carbon dioxide reinjection into the coal in the mining area and control the injection of oxygen into the coal in the mining area, repeating the above process to obtain the first reaction product, the second reaction product and carbon monoxide.

2. The method as described in claim 1, characterized in that, After the reaction yields carbon monoxide, the process further includes: The hydrogen gas and the remaining carbon dioxide in the second reaction product are controlled to react to obtain methanol.

3. The method as described in claim 2, characterized in that, The control, after reacting the hydrogen and remaining carbon dioxide in the second reaction product to obtain methanol, further includes: controlling and detecting the initial carbon dioxide injection amount V9 before the reaction and the remaining carbon dioxide overflow amount V after the reaction. 10 And calculate the carbon dioxide conversion rate, wherein the carbon dioxide conversion rate X = (V9 - V) 10 ) / V9×100%, where V9 is the initial amount of carbon dioxide injected, V 10 This represents the amount of carbon dioxide released.

4. The method as described in claim 2, characterized in that, After controlling the reaction of hydrogen and residual carbon dioxide in the second reaction product to obtain methanol, the method further includes: controlling the metering of methanol production W1 and calculating the methanol yield Y1 = 0.7W1 / (V9 - V 10 ) ×100%.

5. The method as described in claim 2, characterized in that, The control method further includes controlling the reaction of hydrogen and residual carbon dioxide in the second reaction product to obtain methanol, and then controlling the methanol to undergo a methanol-to-olefins reaction to obtain ethylene and propylene.

6. The method as described in claim 5, characterized in that, After controlling the methanol-to-olefins device to produce ethylene and propylene by methanol-to-olefins reaction, the method further includes: controlling the product metering device to measure the ethylene yield W2 and propylene yield W3, and calculating the ethylene yield Y2 and propylene yield Y3, where Y2 = 2.29 W2 / W1 × 100% and Y3 = 2.29 W3 / W1 × 100%.

7. A coal underground gasification carbon dioxide in-situ utilization device, characterized in that, include: Module 1, Module 2, Module 3, and Module 4, wherein: The first module is used to control the injection of oxygen into the coal in the mining area to carry out coal combustion reaction and coal pyrolysis reaction to obtain the first reaction product, control and detect the oxygen intake of the injected oxygen, as well as the carbon dioxide production and oxygen overflow in the first reaction product, and calculate the first reaction criterion. The first reaction coefficient S I = V1 / ( V2-V3), where V1 is the carbon dioxide production, V2 is the oxygen intake, and V3 is the oxygen overflow. The second module is used to determine whether the first reaction threshold has reached the first preset value. If so, it controls the continuous injection of oxygen into the coal in the mining area, and injects water vapor and hydrogen to react and obtain the second reaction product. It controls the detection of the water vapor injection amount, as well as the carbon monoxide production amount and hydrogen production amount in the second reaction product, and calculates the second reaction threshold. The second reaction coefficient S II =(V5+V6) / V4, where V4 is the amount of water vapor injected, V5 is the amount of carbon monoxide produced, and V6 is the amount of hydrogen produced; The third module is used to determine whether the second reaction threshold has reached the second preset value. If so, it controls the stopping of the injection of water vapor and hydrogen, and controls the reinjection of carbon dioxide from the first reaction product and the second reaction product into the coal in the mining area to react and obtain carbon monoxide. It controls the detection of the amount of carbon dioxide injected into the coal in the mining area and the amount of remaining carbon dioxide overflow, and calculates the third reaction threshold. The third reaction coefficient S III =( V7 - V8) / V7, where V7 is the amount of carbon dioxide injected and V8 is the amount of carbon dioxide overflowed; The fourth module is used to determine whether the third reaction standard has reached the third preset value. If so, it controls the stopping of carbon dioxide reinjection into the coal in the mining area and controls the injection of oxygen into the coal in the mining area, repeating the above process to obtain the first reaction product, the second reaction product and carbon monoxide.

8. The apparatus as claimed in claim 7, characterized in that, The third module is also used to control the reaction of hydrogen and the remaining carbon dioxide in the second reaction product to produce methanol after the reaction to obtain carbon monoxide.

9. The apparatus as claimed in claim 8, characterized in that, The third module is also used to control the methanol to olefins reaction to obtain ethylene and propylene.

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