Coal gasification gas waste heat enhanced recovery device and method based on multi-stage thermal cycle

Abstract

The invention discloses a coal gasified gas waste heat enhanced recovery device and method based on multistage thermal cycling, the coal gasified gas waste heat enhanced recovery device comprises a first cooling module, a second cooling module, a vortex tube and a main pipeline used for conveying coal gasified gas, and the gasified gas in the main pipeline is cooled through the first cooling module and the second cooling module in sequence and then communicates with the vortex tube; cooling is carried out through the high-low temperature shunting effect of the vortex tube, gasified gas output by the cold gas end of the vortex tube is used for liquid storage, gasified gas output by the hot gas end is connected into the second cooling module through a branch pipeline to be cooled again, and then the gasified gas is subjected to heat exchange through the preheating injection gas module to the room temperature and then is conveyed remotely. Multi-stage utilization of the heat energy of the gasified gas is achieved, an efficient method for enhanced recovery of the heat energy of the gasified gas is formed, the heat energy utilization efficiency is improved, part of the gasified gas is liquefied and stored, the other part of the gasified gas is subjected to heat exchange to form normal-temperature gasified gas, and thermal damage to long-distance transmission of the pipeline is reduced through long-distance transmission of the pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery, and in particular to a device and method for enhanced recovery of waste heat from coal gasification gas based on a multi-stage heat cycle. Background Art

[0002] Underground coal gasification is a process of controlled combustion of underground coal to produce combustible gas through thermal and chemical effects on coal. my country's energy structure is characterized by "rich in coal, poor in oil, and little gas". Underground coal gasification has two major advantages: clean utilization of coal and low-carbon energy resource guarantee. It is the second-generation coal mining technology for the utilization of abandoned coal resources in old mines and difficult-to-mine coal resources at a depth of more than 1,000 meters. The core issues restricting the large-scale development of underground coal gasification are safety, environmental protection, and economy. Among them, the waste heat of gasified gas in the production well is often not effectively recovered, resulting in a waste of heat energy and reducing the strength and service life of the production well. Summary of the invention

[0003] In view of the defects of the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a coal gasification gas waste heat enhanced recovery device and method based on a multi-stage thermal cycle, which can perform segmented enhanced utilization of the gasification gas waste heat and adopt different methods for recovery and utilization in different temperature ranges.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: a coal gasification gas waste heat enhanced recovery device based on a multi-stage heat cycle, comprising a first cooling module, a second cooling module, a vortex tube and a main pipeline for transporting coal gasification gas, the gasification gas in the main pipeline is cooled by the first cooling module and the second cooling module in turn and then connected to the vortex tube, and is cooled by the high and low temperature shunt effect of the vortex tube, the gasification gas output from the cold gas end of the vortex tube is used for liquid storage, and the gasification gas output from the hot gas end is connected to the second cooling module through a branch pipeline for further cooling, and then is transported over long distances after heat exchange to room temperature through the preheating injection gas module;

[0005] The first cooling module includes a steam generator, a steam turbine, a condenser, a first water pump assembly and a heater assembly which are connected in sequence to form a cycle, wherein the steam turbine is connected to a generator; the second cooling module adopts an organic Rankine cycle, including an evaporator, an expander, a condenser and a liquid pump which are connected in sequence to form a cycle, wherein the expander is connected to a generator.

[0006] Preferably, the main pipeline located at the first cooling module is an L-shaped pipeline, and the main pipeline is provided with a bend at the bottom of the steam generator that extends into the steam generator; the main pipeline and the branch pipeline located at the second cooling module are both U-shaped tubes, and the bend of the U-shaped tube is located in the evaporator, so as to facilitate the full effect of the waste heat energy of the vaporized gas in the first cooling module and the second cooling module.

[0007] The first cooling module, the second cooling module and the preheating injection gas module are all located on the same side of the main pipeline, providing higher space efficiency, facilitating installation in a limited space, thereby saving a large amount of space resources.

[0008] Preferably, the first water pump assembly includes a condensate pump and a main feed water pump, the heater assembly includes a low-pressure heater and a high-pressure heater, the condensate pump, the low-pressure heater, the main feed water pump, and the high-pressure heater are connected in sequence, the condensate pump is connected to the condenser, and the high-pressure heater is connected to the steam generator.

[0009] Preferably, the condenser and the steam condenser are connected to a cooling water source through cooling water pumps respectively equipped therewith to achieve cooling effect.

[0010] Preferably, the organic working fluid in the evaporator adopts r245fa refrigerant, which is non-flammable under normal temperature and pressure conditions and has low toxicity.

[0011] Preferably, the vortex tube includes an interface, a vortex chamber, a guide plate group, a cold air port and a hot air port. The interface is connected to the main pipeline. The guide plate group is used to guide the high-speed rotating outer air flow to the hot air port and prevent it from entering the cold air port, thereby achieving energy separation.

[0012] Preferably, the guide plate group includes a first guide plate and a second guide plate, the first guide plate is a orifice plate whose central aperture does not exceed half of the inner diameter of the vortex chamber and is arranged on the side of the vortex chamber close to the cold air outlet, and the second guide plate is a orifice plate whose annular hole matches the aperture of the first guide plate and is arranged on the side of the vortex chamber close to the hot air outlet.

[0013] The method for enhanced recovery of waste heat from coal gasification gas adopts an enhanced recovery device for waste heat from coal gasification gas based on a multi-stage heat cycle, and comprises the following steps:

[0014] Step 1: The underground gasification gas with a temperature of 400-800°C and a pressure of 1.0-5.0MPa is transported to the ground through insulation measures. The gasification gas transported to the ground has a temperature of 300-600°C and a pressure of 0.5-4.5MPa;

[0015] Step 2: Inject the gasified gas into the steam generator of the first cooling module through the main pipeline, heat the water therein to generate high-temperature and high-pressure steam; the steam is transported to the steam turbine to expand and drive the blades of the steam turbine to rotate, thereby driving the generator to generate electricity, and the steam becomes exhaust steam; the exhaust steam is discharged into the condenser and cooled by cooling water, condensed into water, and the condensed water is concentrated in the lower part of the condenser and converted into hot water through the first water pump assembly and the heater assembly and pumped into the steam generator, forming a cycle;

[0016] Step 3: The temperature of the gasified gas cooled by the first cooling module drops to between 100-150°C, and it is injected into the evaporator of the second cooling module through the main pipeline to heat the low-boiling-point organic working medium; the organic working medium absorbs heat to form steam, and then enters the expander, and drives the main shaft of the expander to rotate through adiabatic expansion to generate electricity. The steam after adiabatic expansion becomes exhaust steam and enters the condenser. Cooling water is continuously injected into the condenser to cool the steam. The cooled organic working medium is pumped into the evaporator by a liquid pump to form an organic Rankine cycle;

[0017] Step 4: The temperature of the gasified gas after passing through the second cooling module is reduced to between 50-100°C, and it is injected into the vortex tube through the main pipeline, and cooled by the high and low temperature shunt effect of the vortex tube; the gasified gas output from the cold air end of the vortex tube is -50-0°C and transported to the liquid storage part;

[0018] Step 5: The gasified gas output from the hot gas end of the vortex tube has a temperature between 100-150°C, and is injected into the evaporator of the second cooling module again, so that the gasified gas temperature drops to between 50-100°C, and then is heat-exchanged to room temperature through the preheating injection gas module;

[0019] Step 6: Transport the gasified gas cooled to room temperature over long distances to achieve multi-stage utilization of the thermal energy of the gasified gas.

[0020] Preferably, in step three, the expander obtains a cycle by continuously taking in air, expanding and exhausting the main shaft for more than one rotation to generate electricity and realize the recovery and utilization of waste heat.

[0021] Beneficial effects of the present invention:

[0022] 1) Utilize steam cycle, organic Rankine cycle and vortex tube to utilize waste heat in gasification gas in stages. Compared with the existing waste heat recovery of coal gasification gas, the waste heat of gasification gas is recovered and utilized in different temperature ranges, especially the waste heat of gasification gas with a temperature between 50-100°C is efficiently utilized, which improves the utilization efficiency of thermal energy, avoids the waste of thermal energy and prolongs the service life of production wells;

[0023] 2) The vortex tube separates the high and low temperature of the gasified gas, effectively reducing the temperature of the gasified gas at the cold gas end, facilitating the liquefaction storage of the gasified gas and reducing its cost. The gasified gas at the hot gas end undergoes an organic Rankine cycle and then undergoes heat exchange in the preheating injection gas module to form room-temperature gasified gas, which can be transported over long distances through pipelines, overcoming the high energy consumption of direct liquefaction of high-temperature gasified gas and reducing the thermal damage of high-temperature gasified gas to long-distance pipeline transmission; BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the principle of the present invention; Figure 2 is a schematic diagram of the structure of the vortex tube; Figure 3 It is a schematic diagram of the structure of the first guide plate and the second guide plate.

[0026] In the figure: 1-steam generator, 2-steam turbine, 3-condenser, 4-condensate pump, 5-low-pressure heater, 6-main feed water pump, 7-high-pressure heater, 8-generator, 9-evaporator, 10-expander, 11-condenser, 12-liquid pump, 13-cooling water pump, 14-vortex tube, 14a-interface, 14b-vortex chamber, 14c-first guide plate, 14d-cold air inlet, 14e-hot air inlet, 14f-second guide plate, 15-preheating injection gas module. DETAILED DESCRIPTION

[0027] In order to better understand the improvements made by the present invention relative to the prior art, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0028] like Figure 1 As shown, a coal gasification gas waste heat enhanced recovery device based on a multi-stage heat cycle is mainly composed of a first cooling module, a second cooling module, a vortex tube 14 and a main pipeline for conveying coal gasification gas. The gasification gas in the main pipeline is cooled by the first cooling module and the second cooling module in turn and then connected to the vortex tube 14. Gradual recovery and utilization are adopted for gasification gases of different temperatures, thereby improving the utilization efficiency of thermal energy and avoiding the waste of thermal energy.

[0029] The first cooling module is mainly composed of a steam generator 1, a steam turbine 2, a condenser 3, a first water pump assembly and a heater assembly which are connected in sequence to form a cycle, wherein the steam turbine 2 is connected to a generator 8. The first water pump assembly includes a condensate pump 4 and a main feed water pump 6, and the heater assembly includes a low-pressure heater 5 and a high-pressure heater 7. The condensate pump 4, the low-pressure heater 5, the main feed water pump 6 and the high-pressure heater 7 are connected in sequence, the condensate pump 4 is connected to the condenser 3, and the high-pressure heater 7 is connected to the steam generator 1. The condensate is concentrated in the lower part of the condenser 3 and pumped to the low-pressure heater 5 by the condensate pump 4, and then to the high-pressure heater 7 through the main feed water pump 6. The heated hot water is pumped into the steam generator 1 to form a water vapor cycle.

[0030] The second cooling module adopts an organic Rankine cycle, using low-boiling-point organic working fluids instead of water vapor, and can use low-temperature heat sources with temperatures between 90°C and 300°C to convert low-grade thermal energy into high-grade electrical energy. The second cooling module is mainly composed of an evaporator 9, an expander 10, a condenser 11, and a liquid pump 12, which are connected in sequence to form a cycle, wherein the expander 10 is connected to a generator 8. The organic working fluid in the evaporator 9 uses r245fa refrigerant, which has a boiling point of about 15.3°C. It is a volatile colorless liquid with a sweet smell. It is non-flammable under normal temperature and pressure conditions and has low toxicity. In the first cooling module and the second cooling module, the condenser 3 and the condenser 11 are connected to the cooling water source through their respective cooling water pumps 13 to achieve a cooling effect, which can quickly cool the gas into a liquid for the next cycle.

[0031] The main pipeline is an L-shaped pipeline at the first cooling module, and the main pipeline is provided with a bend extending into the steam generator 1 at the bottom of the steam generator 1. The main pipeline and the branch pipeline are both U-shaped pipes at the second cooling module, and the bend of the U-shaped pipe is located in the evaporator 9. At the same time, the first cooling module, the second cooling module and the preheating injection gas module 15 are all located on the same side of the main pipeline, providing higher space efficiency, so as to facilitate installation in a limited space, thereby saving a lot of space resources.

[0032] The gasified gas cooled by the first cooling module and the second cooling module is cooled by the high and low temperature shunting effect of the vortex tube 14. The gasified gas output from the cold gas end of the vortex tube 14 is used for liquid storage, and the gasified gas output from the hot gas end is connected to the second cooling module through a branch pipe for further cooling, and then heat-exchanged to room temperature by the preheating injection gas module 15 for long-distance transportation. Figure 2 As shown, the vortex tube 14 comprises an interface 14a, a vortex cavity 14b, a guide plate group, a cold air port 14d and a hot air port 14e. The interface 14a is connected to the main pipeline. When the gasified gas enters the vortex tube 14 at high speed, the airflow forms a strong rotation motion in the vortex tube 14, resulting in temperature separation of the internal gas. The guide plate group is used to guide the high-speed rotating outer airflow to the hot air port 14e, while preventing it from entering the cold air port 14d, thereby achieving energy separation. The guide plate group is mainly composed of a first guide plate 14C and a second guide plate 14f. The first guide plate 14C is a hole plate with a central aperture not exceeding half of the inner diameter of the vortex chamber 14b and is arranged on the side of the vortex chamber 14b close to the cold air outlet 14d. The second guide plate 14f is a hole plate with an annular hole matching the aperture of the first guide plate 14C and is arranged on the side of the vortex chamber 14b close to the hot air outlet 14e. During operation, the proportion of cold and hot air flows can be adjusted by adjusting the aperture size of the guide plate group to accurately control the temperature. When the cold air outlet 14d needs to be expanded, the cold air outlet 14d can be set to a cone with a cone angle not exceeding 15°.

[0033] A method for enhanced recovery of waste heat from coal gasification gas, using the above-mentioned device for enhanced recovery of waste heat from coal gasification gas based on a multi-stage heat cycle, has the following specific steps:

[0034] Step 1: Underground gasification gas with a temperature of 400-800°C and a pressure of 1.0-5.0MPa is transported to the ground through insulation measures. The temperature of the gasification gas transported to the ground is 300-600°C and the pressure is 0.5-4.5MPa.

[0035] Step 2: Inject the gasified gas into the steam generator 1 of the first cooling module through the main pipeline, heat the water therein to produce high-temperature and high-pressure steam. The steam is transported to the steam turbine 2 and expands to drive the turbine blades to rotate, thereby driving the generator 8 to generate electricity, and the steam becomes exhaust steam. The exhaust steam is discharged into the condenser 3 and cooled by cooling water, condensed into water, and the condensed water is concentrated in the lower part of the condenser and converted into hot water through the first water pump assembly and the heater assembly and pumped into the steam generator 1, forming a cycle.

[0036] Step 3: The temperature of the gasified gas cooled by the first cooling module drops to between 100-150°C, and it is injected into the evaporator 9 of the second cooling module through the main pipeline to heat the low-boiling-point organic working medium. The organic working medium absorbs heat to form steam, and then enters the expander 10, and drives the main shaft of the expander 10 to rotate through adiabatic expansion to generate electricity. The expander 10 rotates the main shaft for more than one cycle through continuous intake, expansion and exhaust, thereby achieving a cycle and recycling of waste heat. The steam after adiabatic expansion becomes exhaust steam and enters the condenser 11. Cooling water is continuously injected into the condenser 11 to cool the steam. The cooled organic working medium is sent to the evaporator 9 by the liquid pump 12 to form an organic Rankine cycle.

[0037] Step 4: The gasified gas temperature after passing through the second cooling module is reduced to between 50-100°C, and is injected into the vortex tube 14 through the main pipeline, and is cooled by the high and low temperature shunt effect of the vortex tube. The gasified gas output from the cold air end of the vortex tube 14 is -50-0°C and is transported to the liquid storage part.

[0038] Step 5: The gasified gas output from the hot gas end of the vortex tube 14 has a temperature between 100-150°C, and is injected into the evaporator 9 of the second cooling module again, so that the gasified gas temperature drops to between 50-100°C, and then is heat-exchanged to room temperature through the preheating injection gas module 15.

[0039] Step 6: Transport the gasified gas cooled to room temperature over long distances to achieve multi-stage utilization of the thermal energy of the gasified gas.

[0040] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A coal gasification gas waste heat enhanced recovery device based on a multi-stage heat cycle, characterized in that: It comprises a first cooling module, a second cooling module, a vortex tube (14) and a main pipeline for transporting coal gasification gas, wherein the gasification gas in the main pipeline is cooled by the first cooling module and the second cooling module in sequence and then connected to the vortex tube (14), and is cooled by the high and low temperature shunt effect of the vortex tube (14), the gasification gas output from the cold gas end of the vortex tube (14) is used for liquid storage, and the gasification gas output from the hot gas end is connected to the second cooling module through a branch pipeline for further cooling, and then is transported over a long distance after heat exchange to room temperature through a preheating injection gas module (15); The first cooling module comprises a steam generator (1), a steam turbine (2), a condenser (3), a first water pump assembly and a heater assembly which are connected in sequence to form a cycle, wherein the steam turbine (2) is connected to a generator (8); the second cooling module adopts an organic Rankine cycle, comprising an evaporator (9), an expander (10), a condenser (11) and a liquid pump (12) which are connected in sequence to form a cycle, wherein the expander (10) is connected to a generator (8).

2. The device for enhanced recovery of waste heat from coal gasification gas based on multi-stage heat cycle according to claim 1 is characterized in that: The main pipeline located at the first cooling module is an L-shaped pipeline, and the main pipeline is provided with a bend extending into the steam generator (1) at the bottom of the steam generator (1); the main pipeline and the branch pipeline located at the second cooling module are both U-shaped tubes, and the bend of the U-shaped tube is located inside the evaporator (9).

3. The device for enhanced recovery of waste heat from coal gasification gas based on multi-stage heat cycle according to claim 2 is characterized in that: The first cooling module, the second cooling module and the preheating injection gas module (15) are all located on the same side of the main pipeline.

4. The device for enhanced recovery of waste heat from coal gasification gas based on multi-stage heat cycle according to claim 1, characterized in that: The first water pump assembly comprises a condensate pump (4) and a main feed water pump (6), and the heater assembly comprises a low-pressure heater (5) and a high-pressure heater (7). The condensate pump (4), the low-pressure heater (5), the main feed water pump (6), and the high-pressure heater (7) are connected in sequence, the condensate pump (4) is connected to the condenser (3), and the high-pressure heater (7) is connected to the steam generator (1).

5. The device for enhanced recovery of waste heat from coal gasification gas based on multi-stage heat cycle according to claim 1, characterized in that: The condenser (3) and the condenser (11) are connected to a cooling water source via cooling water pumps (13) respectively provided therewith to achieve a cooling effect.

6. The device for enhanced recovery of waste heat from coal gasification gas based on multi-stage heat cycle according to claim 1, characterized in that: The organic working medium in the evaporator (9) is R245FA refrigerant.

7. The device for enhanced recovery of waste heat from coal gasification gas based on multi-stage heat cycle according to claim 1, characterized in that: The vortex tube (14) comprises an interface (14a), a vortex chamber (14b), a guide plate group, a cold air outlet (14d) and a hot air outlet (14e); the interface (14a) is connected to the main pipeline; the guide plate group is used to guide the high-speed rotating outer airflow to the hot air outlet (14e) and prevent it from entering the cold air outlet (14d), thereby achieving energy separation.

8. The device for enhanced recovery of waste heat from coal gasification gas based on multi-stage heat cycle according to claim 7, characterized in that: The guide plate group comprises a first guide plate (14C) and a second guide plate (14f); the first guide plate (14C) is a hole plate with a central aperture not exceeding half of the inner diameter of the vortex chamber (14b) and is arranged on a side of the vortex chamber (14b) close to the cold air outlet (14d); the second guide plate (14f) is a hole plate with an annular hole matching the aperture of the first guide plate (14C) and is arranged on a side of the vortex chamber (14b) close to the hot air outlet (14e).

9. A method for enhanced recovery of waste heat from coal gasification gas, characterized in that: The device for enhanced recovery of waste heat from coal gasification gas based on a multi-stage heat cycle as described in any one of claims 1 to 8 comprises the following steps: Step 1: The underground gasification gas with a temperature of 400-800°C and a pressure of 1.0-5.0MPa is transported to the ground through insulation measures. The gasification gas transported to the ground has a temperature of 300-600°C and a pressure of 0.5-4.5MPa; Step 2: injecting the gasified gas into the steam generator (1) of the first cooling module through the main pipeline, heating the water therein to generate high-temperature and high-pressure water vapor; the water vapor is transported to the steam turbine (2) to expand and drive the blades of the steam turbine to rotate, thereby driving the generator (8) to generate electricity, and the water vapor becomes exhaust steam; the exhaust steam is discharged into the condenser (3) and cooled by cooling water to condense into water, and the condensed water is collected at the lower part of the condenser and converted into hot water through the first water pump assembly and the heater assembly and pumped into the steam generator (1), forming a cycle; Step 3: The temperature of the gasified gas cooled by the first cooling module drops to between 100° C. and 150° C., and the gasified gas is injected into the evaporator (9) of the second cooling module through the main pipeline to heat the low-boiling-point organic working medium; the organic working medium absorbs heat to form steam, and then enters the expander (10), and drives the main shaft of the expander (10) to rotate through adiabatic expansion to generate electricity; the steam after adiabatic expansion becomes exhaust steam and enters the condenser (11), and cooling water is continuously injected into the condenser (11) to cool the steam. The cooled organic working medium is sent to the evaporator (9) by the liquid pump (12), forming an organic Rankine cycle; Step 4: The temperature of the gasified gas after passing through the second cooling module is reduced to between 50° C. and 100° C., and the gasified gas is injected into the vortex tube (14) through the main pipeline, and is cooled by the high and low temperature shunt effect of the vortex tube; the gasified gas output from the cold air end of the vortex tube (14) is -50-0° C. and is transported to the liquid storage component; Step 5: The gasified gas output from the hot gas end of the vortex tube (14) has a temperature between 100 and 150° C., and is injected again into the evaporator (9) of the second cooling module to reduce the temperature of the gasified gas to between 50 and 100° C., and then is heat-exchanged to room temperature through the preheating injection gas module (15); Step 6: Transport the gasified gas cooled to room temperature over long distances to achieve multi-stage utilization of the thermal energy of the gasified gas.

10. The method for enhanced recovery of waste heat from coal gasification gas according to claim 9, characterized in that: In step three, the expander (10) obtains a cycle by rotating the main shaft for more than one revolution through continuous intake, expansion and exhaust, thereby generating electricity and realizing the recovery and utilization of waste heat.

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