Automatic drainage system for underground coal gasification product conveying process

Abstract

The utility model relates to the technical field of underground coal gasification product conveying processes, and particularly discloses an automatic liquid drainage system for an underground coal gasification product conveying process. The automatic liquid discharge system for the underground coal gasification product conveying process comprises a three-phase separation tank, the three-phase separation tank is communicated with a product well through a first synthesis gas pipeline, and the three-phase separation tank is used for removing part of moisture, tar and solid dust entrained in synthesis gas, so that condensate is separated out, and the product well is communicated with the product well through a second synthesis gas pipeline. The top of the three-phase separation tank is communicated with a second synthesis gas pipeline, and the second synthesis gas pipeline is used for conveying synthesis gas without condensate; the automatic liquid discharging system for the underground coal gasification product conveying process is reasonable in process design, has dual functions of cooling synthesis gas and collecting condensate, is high in process automation level, does not need manual operation, can be installed outdoors, does not need a heat insulation layer, reduces the investment and production cost of a project, and is suitable for popularization and application. And the workload of a downstream purification treatment system is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of underground coal gasification product transportation technology, and in particular relates to an automatic liquid discharge system used in underground coal gasification product transportation technology. Background Art

[0002] Underground coal gasification (ISC) is a process that converts coal directly into product gas, usually called synthesis gas, by combustion and gasification of underground coal seams in the presence of an oxidant. The synthesis gas can then be used as a feedstock for a variety of applications, including fuel production, chemical production, and power generation. This underground coal gasification technology is applicable to most coal deposits. In view of the increasingly stringent environmental requirements for the mining industry and considering the related labor and infrastructure costs, this technology is undoubtedly very attractive.

[0003] Surface wells penetrate the coal seam directly, providing an effective channel for oxidant injection and product gas production. A pair of wells are connected or extended horizontally underground to form a substantially horizontal drilling channel (also referred to as a coal seam well or connecting channel). This channel facilitates oxidant injection, combustion zone growth and product gas transportation. A well used for oxidant injection is called an "injection well" and the other well used for producing product gas is called a "product well". Both directional horizontal drilling and vertical drilling can be used as injection wells or product wells. Underground coal gasification (ISC) may also require the use of one or more vertical wells (e.g., functional wells and auxiliary wells) between the injection well and the product well.

[0004] When there are injection wells, product wells and horizontal channels connecting the two in a coal seam, this structure is called an underground coal gasification (ISC) unit or well pair. The ISC unit includes a combustion zone, a gasification zone and a pyrolysis zone. Among them, the combustion zone is near the oxidant injection point in the coal seam; the gasification zone surrounds the combustion zone in a radial form or is downstream of the combustion zone. The coal is gasified and partially oxidized in the gasification zone to generate product gas; the pyrolysis zone is downstream of the gasification zone, and the pyrolysis reaction of coal generally occurs here. The high-temperature product gas flows downstream from the gasification zone and is eventually transported to the ground from the wellhead of the product well. While the coal is burning or gasifying, the ISC combustion zone in the coal seam will grow and become larger.

[0005] The product gas (raw synthesis gas) generated by underground coal gasification usually contains synthesis gas (a mixture of CO, CO2, H2, CH4 and other gases) and other solid particles, water, coal tar, hydrocarbon vapor, and other trace components including H2S, NH3, COS, etc.). The complexity of its composition depends on many aspects: the oxidant used in underground coal gasification (air or other oxidants, such as oxygen, oxygen-enriched air or steam mixture), the intrinsic water in the coal seam or the water infiltrating into the coal seam from the surrounding strata, the coal quality, and the operating parameters of the underground coal gasification process, including temperature, pressure, etc.

[0006] Traditional product gas transportation generally requires manual operation and has a low level of automation. In addition, traditional transportation devices generally rely on cooling water to condense the gas, which consumes a lot of energy and has relatively high costs. Utility Model Content

[0007] The purpose of the utility model is to provide an automatic liquid discharge system for underground coal gasification product transportation process with simple structure and reasonable design in order to solve the above problems.

[0008] The utility model achieves the above-mentioned purpose through the following technical solutions:

[0009] An automatic liquid discharge system for underground coal gasification product transportation process, comprising a three-phase separation tank, the three-phase separation tank is connected to a product well through a first synthesis gas pipeline, the three-phase separation tank is used to remove part of the water, tar and solid dust entrained in the synthesis gas, so as to separate the condensate, the top of the three-phase separation tank is connected to a second synthesis gas pipeline, and the second synthesis gas pipeline is used to transport the synthesis gas after the condensate is removed;

[0010] The three-phase separation tank is also connected to a condensate pipe through an outlet pipe, and the condensate pipe is connected to the middle position of the side wall of the three-phase separation tank. The bottom of the three-phase separation tank is connected to a slag bucket, and the slag bucket is used to collect solid ash. A control component is provided on the outlet pipe, and the control component is used to control the connection state between the three-phase separation tank and the condensate pipe.

[0011] Furthermore, a solvent injection device is connected to the second synthesis gas pipeline, and the solvent injection device is used to inject a solvent into the synthesis gas in the second synthesis gas pipeline.

[0012] Furthermore, a plurality of condensate collection systems are provided on the second synthesis gas pipeline, and the output end of the condensate collection system is connected to the condensate pipeline. The condensate collection system includes a condensate collection tank, and the condensate collection tank is used to collect condensate condensed during the synthesis gas transportation process. An inlet valve is provided between the condensate collection tank and the second synthesis gas pipeline.

[0013] Furthermore, a condensate collecting tank level gauge is provided on the condensate collecting tank, a condensate collecting tank level regulating valve is provided between the condensate collecting tank and the condensate pipeline, and a second check valve is provided between the condensate collecting tank level regulating valve and the condensate pipeline.

[0014] Furthermore, the control component includes a three-phase separation tank level gauge and a three-phase separation tank level regulating valve, and a first check valve is provided between the three-phase separation tank level regulating valve and the condensate pipeline.

[0015] Furthermore, a slag discharge valve is provided between the three-phase separation tank and the slag bucket.

[0016] Furthermore, the first synthesis gas pipeline and the second synthesis gas pipeline are both provided with thermocouple temperature measuring points, and thermometers are provided at the thermocouple temperature measuring points.

[0017] Furthermore, the end of the second synthesis gas pipeline away from the three-phase separation tank is connected to a synthesis gas post-processing system, and the end of the condensate pipeline is connected to a downstream waste liquid treatment system.

[0018] The beneficial effects of the utility model are: the utility model has a reasonable process design, has the dual functions of cooling synthesis gas and collecting condensate, has a high level of process automation, does not require manual operation, can be installed in the open air, does not need to install a heat insulation layer, reduces the investment and production costs of the project, reduces the workload of the downstream purification treatment system, does not require any external energy, and the system is fully automated, which can reduce human resource expenditures and improve the economic benefits of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the automatic liquid discharge system used in the underground coal gasification product transportation process of the utility model;

[0020] Figure 2 It is a schematic diagram of the condensate collection system of the utility model.

[0021] In the figure: 1. product well; 2. first synthesis gas pipeline; 3. three-phase separation tank; 4. slag barrel; 5. slag discharge valve; 6. three-phase separation tank level gauge; 7. three-phase separation tank level regulating valve; 8. first check valve; 9. thermometer; 10. solvent injection device; 11. outlet valve; 12. second synthesis gas pipeline; 13. condensate pipeline; 14. condensate collection system; 15. synthesis gas post-treatment system; 16. downstream waste liquid treatment system; 17. inlet valve; 18. condensate collection tank; 19. condensate collection tank level gauge; 20. condensate collection tank level regulating valve; 21. second check valve. DETAILED DESCRIPTION

[0022] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0023] like Figure 1-Figure 2 As shown, an automatic liquid discharge system for underground coal gasification product transportation process includes a three-phase separation tank 3, which is connected to a product well 1 through a first synthesis gas pipeline 2, and is used to remove part of the moisture, tar and solid dust entrained in the synthesis gas, thereby separating the condensate, and the top of the three-phase separation tank 3 is connected to a second synthesis gas pipeline 12, and the second synthesis gas pipeline 12 is used to transport the synthesis gas after the condensate is removed;

[0024] The three-phase separation tank 3 is also connected to a condensate pipe 13 through an outlet pipe. The condensate pipe 13 is connected to the middle of the side wall of the three-phase separation tank 3. The bottom of the three-phase separation tank 3 is connected to a slag bucket 4, which is used to collect solid ash. A control component is provided on the outlet pipe, and the control component is used to control the connection state between the three-phase separation tank 3 and the condensate pipe 13.

[0025] The synthesis gas from the product well 1 first enters the middle of the three-phase separation tank 3 to remove part of the water, tar and solid dust entrained in the gas. The synthesis gas after removing the condensate goes out from the second synthesis gas pipeline 12 at the top of the three-phase separation tank 3, and the separated condensate is discharged from the middle of the three-phase separation tank 3 into the condensate pipeline 13, while the solid ash is discharged into the slag bucket 4 through the bottom of the three-phase separation tank 3. The size and form of the three-phase separation tank need to be calculated according to the synthesis gas flow rate and the amount of entrained water and solid under different conditions;

[0026] When the liquid level reaches the first liquid level, the control component controls the connection between the three-phase separation tank 3 and the condensate pipeline 13 to discharge the liquid. When the third liquid level is reached, the control component controls the isolation of the three-phase separation tank 3 and the condensate pipeline 13 to end the drainage. This cycle repeats, wherein the first liquid level is higher than the third liquid level.

[0027] In a specific implementation, a solvent injection device 10 is connected to the second synthesis gas pipeline 12 , and the solvent injection device 10 is used to inject a solvent into the synthesis gas in the second synthesis gas pipeline 12 .

[0028] It should be noted that the purpose of injecting solvent into the second synthesis gas pipeline 12 by using the solvent injection device 10 is to prevent the tar in the synthesis gas from condensing and blocking the pipeline during its transportation, so that the downstream condensate flows more smoothly. The solvent can be selected from organic solvents such as methanol, ethanol or acetone. The specific selection needs to be determined according to the temperature of the project location to avoid the freezing of the pipeline in winter. The injection amount of the solvent is determined according to the synthesis gas flow rate, the tar content and the condensation point.

[0029] In a specific embodiment, a plurality of condensate collection systems 14 are provided on the second synthesis gas pipeline 12, and the output end of the condensate collection system 14 is connected to the condensate pipeline 13. The condensate collection system 14 includes a condensate collection tank 18, which is used to collect condensate condensed during the synthesis gas transportation process. An inlet valve 17 is provided between the condensate collection tank 18 and the second synthesis gas pipeline 12.

[0030] Among them, the condensate collection tank 18 is used to collect the condensate condensed during the synthesis gas transportation process in the second synthesis gas pipeline 12. The size of the condensate collection tank 18 can be determined according to the amount of condensate required to be collected under different conditions. The material of the condensate collection tank 18 is selected to be an anti-corrosion material above 316L.

[0031] In a specific implementation, a condensate collecting tank level gauge 19 is also provided on the condensate collecting tank 18 , a condensate collecting tank level regulating valve 20 is provided between the condensate collecting tank 18 and the condensate pipeline 13 , and a second check valve 21 is provided between the condensate collecting tank level regulating valve 20 and the condensate pipeline 13 .

[0032] It should be noted that an automatic control valve is respectively set before and after the condensate collection tank 18. The opening and closing interval time and the condensate collection time of the two automatic control valves can be set according to the calculation of different synthesis gas components. The liquid level of the condensate collection tank 18 is measured by the condensate collection tank level gauge 19, and the discharge of the condensate collection tank 18 is controlled by the condensate collection tank level regulating valve 20. Among them, the second check valve 21 is to prevent the gas in the pipeline from flowing back and affecting the operation of the entire system.

[0033] Condensate collection tank 18 drainage control method 1:

[0034] The inlet valve 17 and the condensate collection tank level regulating valve 20 are opened at certain staggered time intervals to allow each condensate collection tank 18 to be emptied at once. The second synthesis gas pipeline 12 uses gravity to discharge the condensate into the condensate collection tank 18. After about half a minute or one minute (10-60 seconds, the time needs to be calculated according to different situations), the inlet valve 17 is closed, the condensate collection tank level regulating valve 20 is opened, and the condensate is discharged into the condensate pipeline 13 by gravity and the pipeline pressure accumulated in the condensate collection tank 18; then the condensate collection tank level regulating valve 20 is closed again before opening the inlet valve 17, and the inlet valve 17 is opened to discharge the condensate from the second synthesis gas pipeline 12 to the condensate collection tank 18. The condensate is discharged from the condensate collection tank 18 closest to the three-phase separation tank 3, and then the process is repeated along each downstream pipeline condensate collection tank system of the pipeline until the inlet valve 17 of the condensate collection tank 18 closest to the three-phase separation tank 3 is opened again. For example, if the opening and closing time is 10 seconds, the waiting time between each pipeline condensate collection tank 18 is 5 seconds, and there are 10 of them, then it will take about 150 seconds for the inlet valve 17 of the first condensate collection tank 18 to open again;

[0035] Condensate collection tank 18 drainage control method 2:

[0036] The inlet valve 17 is normally open, and the condensate collection tank liquid level regulating valve 20 is normally closed. When the liquid level in the condensate collection tank 18 reaches the second liquid level, the condensate collection tank liquid level regulating valve 20 is opened, and the liquid is discharged by utilizing the gravity of the liquid in the condensate collection tank 18 and the pressure of the second synthesis gas pipeline 12. When the liquid level reaches the fourth liquid level, the condensate collection tank liquid level regulating valve 20 is closed to continue collecting liquid. When the liquid level reaches the first liquid level, the inlet valve 17 is closed until the liquid level drops to the second liquid level and then opened (increasing the discharge speed). When the liquid level drops to the fourth liquid level, the inlet valve 17 is closed to prevent gas from entering the condensate pipeline 13.

[0037] Condensate collection tank 18 drainage control method three:

[0038] It is controlled by the liquid level of the condensate collection tank 18. The inlet valve 17 is normally open, and the condensate collection tank liquid level regulating valve 20 is normally closed. When the liquid level reaches the second liquid level, the condensate collection tank liquid level regulating valve 20 is opened, and the liquid is discharged by the gravity of the liquid in the condensate collection tank 18 and the pressure of the second synthesis gas pipeline 12. When the liquid level reaches the fourth liquid level, the condensate collection tank liquid level regulating valve 20 is closed to continue collecting liquid. When the liquid level reaches the first liquid level, the inlet valve 17 is closed until the liquid level drops to the second liquid level and then opened (increase the discharge speed). When the liquid level drops to the fourth liquid level, the inlet valve 17 is closed to prevent gas from entering the condensate pipeline 13.

[0039] It should be noted that, in the above three control modes, the first liquid level is greater than the second liquid level, which is greater than the fourth liquid level, which is greater than the third liquid level.

[0040] In a specific implementation, the control component includes a three-phase separation tank level meter 6 and a three-phase separation tank level regulating valve 7 . A first check valve 8 is provided between the three-phase separation tank level regulating valve 7 and the condensate pipeline 13 .

[0041] The liquid level in the three-phase separation tank 3 is measured by the three-phase separation tank level meter 6, and the three-phase separation tank 3 is drained by the three-phase separation tank level regulating valve 7. The first check valve 8 is to prevent gas backflow and affect the operation of the entire system.

[0042] In a specific implementation, a slag discharge valve 5 is provided between the three-phase separation tank 3 and the slag bucket 4 .

[0043] In a specific implementation, thermocouple temperature measuring points are provided on the first synthesis gas pipeline 2 and the second synthesis gas pipeline 12 , and thermometers 9 are provided at the thermocouple temperature measuring points.

[0044] In actual settings, thermocouple temperature measuring points can be set on the product well 1, the three-phase separation tank 3 and the second synthesis gas pipeline 12. The specific positions and numbers of the thermocouple temperature measuring points can be set according to the length of the pipeline, and the temperature signals are sent to the central control room so as to monitor the temperatures of these positions at any time.

[0045] In a specific embodiment, the end of the second synthesis gas pipeline 12 away from the three-phase separation tank 3 is connected to the synthesis gas post-treatment system 15 , and the end of the condensate pipeline 13 is connected to the downstream waste liquid treatment system 16 .

[0046] In the technical solution of the present application, the size and wall thickness of the first syngas pipeline 2 and the second syngas pipeline 12 need to be calculated based on data such as syngas flow and pressure under different conditions of different projects; the size of the condensate pipeline 13 can be designed according to the condensate discharge volume, and the material selection requires anti-corrosion materials of grade 316L or above.

[0047] Furthermore, solvents such as methanol, ethanol, ethylene glycol, and acetone can be recovered from process water by distilling solvents from process water and process condensate streams using waste heat from synthesis gas. Various commonly used industrial heat exchange methods can be used for this purpose.

[0048] If there is no special explanation, the materials used in the equipment pipelines of the embodiments of the present invention are 316 stainless steel, nickel-chromium alloy, nickel-copper alloy and other materials with good corrosion resistance, and the control schemes used in the embodiments are all conventional methods in the art.

[0049] Before using the process system of the synthesis gas cooling and automatic liquid drainage system, firstly, the gasifier needs to produce gas, and secondly, the synthesis gas post-treatment system 15 and the downstream waste liquid treatment system 16 need to be able to operate normally;

[0050] All valves and the three-phase separation tank level gauge 6 of the system need to be installed and tested for leaks and debugged. The system can only be activated if there is no leakage and the debugging is qualified.

[0051] The above embodiments only express several implementation methods of the utility model, and the descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model.

Claims

1. An automatic liquid discharge system for underground coal gasification product transportation process, comprising a product well (1) and a first synthesis gas pipeline (2), wherein the underground coal gasification product is output from the product well (1) and transported through the first synthesis gas pipeline (2), characterized in that: The three-phase separation tank (3) is connected to the product well (1) through the first synthesis gas pipeline (2), and the three-phase separation tank (3) is used to remove part of the water, tar and solid dust entrained in the synthesis gas, thereby separating the condensate. The top of the three-phase separation tank (3) is connected to the second synthesis gas pipeline (12), and the second synthesis gas pipeline (12) is used to transport the synthesis gas after the condensate is removed; The three-phase separation tank (3) is also connected to a condensate pipe (13) via an outlet pipe, the condensate pipe (13) is connected to the middle of the side wall of the three-phase separation tank (3), the bottom of the three-phase separation tank (3) is connected to a slag bucket (4), the slag bucket (4) is used to collect solid ash, and a control component is provided on the outlet pipe, the control component is used to control the connection state between the three-phase separation tank (3) and the condensate pipe (13); The end of the second synthesis gas pipeline (12) away from the three-phase separation tank (3) is connected to a synthesis gas post-treatment system (15), and the end of the condensate pipeline (13) is connected to a downstream waste liquid treatment system (16).

2. The automatic liquid discharge system for underground coal gasification product transportation process according to claim 1, characterized in that: The second synthesis gas pipeline (12) is connected to a solvent injection device (10), and the solvent injection device (10) is used to inject a solvent into the synthesis gas in the second synthesis gas pipeline (12).

3. The automatic liquid drainage system for underground coal gasification product transportation process according to claim 2, characterized in that: The second synthesis gas pipeline (12) is provided with a plurality of condensate collection systems (14), the output end of the condensate collection system (14) is connected to the condensate pipeline (13), the condensate collection system (14) comprises a condensate collection tank (18), the condensate collection tank (18) is used to collect condensate condensed during the synthesis gas transportation process, and an inlet valve (17) is provided between the condensate collection tank (18) and the second synthesis gas pipeline (12).

4. The automatic liquid discharge system for underground coal gasification product transportation process according to claim 3, characterized in that: The condensate collecting tank (18) is also provided with a condensate collecting tank level gauge (19), a condensate collecting tank level regulating valve (20) is provided between the condensate collecting tank (18) and the condensate pipeline (13), and a second check valve (21) is provided between the condensate collecting tank level regulating valve (20) and the condensate pipeline (13).

5. An automatic liquid drainage system for underground coal gasification product transportation process according to any one of claims 1 to 4, characterized in that: The control component comprises a three-phase separation tank liquid level meter (6) and a three-phase separation tank liquid level regulating valve (7), and a first check valve (8) is arranged between the three-phase separation tank liquid level regulating valve (7) and the condensate pipeline (13).

6. The automatic liquid discharge system for underground coal gasification product transportation process according to claim 5, characterized in that: A slag discharge valve (5) is provided between the three-phase separation tank (3) and the slag bucket (4).

7. The automatic liquid discharge system for underground coal gasification product transportation process according to claim 6, characterized in that: The first synthesis gas pipeline (2) and the second synthesis gas pipeline (12) are both provided with thermocouple temperature measuring points, and thermometers (9) are provided at the thermocouple temperature measuring points.

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