Liquid carbon dioxide overpressure power generation device

Abstract

The utility model relates to low temperature methanol washing technical field, is a kind of liquid carbon dioxide overpressure power generation device, it includes purification separation unit, liquefied unit, pressure reducing power generation unit, purification separation unit import fixed communication has first raw material shift gas pipeline, fixed communication has first desulfurization shift gas pipeline between purification separation unit export and liquefied unit import, fixed communication has high pressure liquid transfer line between liquefied unit export and pressure reducing power generation unit import, fixed communication has carbon dioxide condensate line in pressure reducing power generation unit export, pressure reducing power generation unit includes turbine, generator, medium-pressure flash tank, turbine is connected with generator, fixed communication has low pressure liquid transfer line between turbine export and medium-pressure flash tank import between.The utility model is reasonable and compact in structure, convenient to use, it uses the structure of turbine and spare pressure reducing valve parallel connection, converts pressure energy into mechanical energy, finally converts into electric energy, solves the production interruption problem caused by single pressure reducing equipment failure.

Description

Technical Field

[0001] This utility model relates to the field of low-temperature methanol washing technology and is a liquid carbon dioxide residual pressure power generation device. Background Technology

[0002] The coal gasification process for producing urea uses coal as raw material. The production process involves producing syngas through coal gasification. After conversion and purification, the syngas is used to synthesize ammonia and then reacts with carbon dioxide to produce urea. The entire process can be divided into four core components: coal gasification and syngas production, syngas purification and conversion, ammonia synthesis, and urea synthesis and processing.

[0003] The syngas exiting the coal gasification furnace, after preliminary dust removal and washing, primarily consists of carbon monoxide (CO) and hydrogen (H2), but also contains impurities such as carbon dioxide (CO2), hydrogen sulfide (H2S), and carbonyl sulfide (COS). This syngas undergoes a water-gas shift reaction to produce feedstock shift gas, significantly increasing the H2 content and decreasing the CO content, thus meeting the requirements for subsequent pure hydrogen production (for ammonia synthesis). The shift reaction also produces an equimolar amount of CO2, providing feedstock CO2 for urea synthesis. Therefore, shift gas is the source for subsequent CO2 capture and recovery. Subsequent purification units remove and recover high-purity CO2 from the shift gas, using a portion for urea synthesis and a portion for liquid carbon dioxide production. Liquid carbon dioxide comes in two types: industrial grade for underground oil recovery and food grade for addition to food products. The remainder becomes emissions requiring treatment. The shift gas cannot be used directly and must undergo strict purification treatment. Firstly, physical / chemical methods (such as low-temperature methanol washing) are used to simultaneously remove H2S / COS and CO2 from the shift gas. The removed CO2 has a very high purity (>99%) and, after being pressurized, is used as a raw material for urea synthesis. Secondly, the purified gas (containing almost only H2) is called purified gas and is used as a raw material for ammonia synthesis.

[0004] Currently, in the low-temperature methanol washing process, the shifted gas consists of a high-pressure carbon dioxide product with a pressure of approximately 0.57 MPaG and a low-pressure carbon dioxide product with a pressure of approximately 0.2 MPaG. During the process of transferring the liquid medium from the gas-liquid separator to the medium-pressure flash tank, a pressure reducing valve is typically used to reduce the high pressure (5.75 MPa) at the liquid phase outlet of the gas-liquid separator to the pressure required by the medium-pressure flash tank (2.2 MPa). During this period, the pressure energy (residual pressure) of the high-pressure liquid is directly dissipated at the pressure reducing valve through throttling, without being effectively utilized. Furthermore, the pressure reducing valve requires long-term maintenance. During the throttling and pressure reduction process, the fluid state is unstable, and the liquid may experience localized flashing due to a sudden pressure drop, leading to accelerated wear of the pressure reducing valve core, affecting equipment lifespan and pressure reduction accuracy. When the pressure reducing valve malfunctions or requires maintenance, the liquid phase transfer is interrupted, affecting the normal operation of the subsequent medium-pressure flash tank and reducing production stability.

[0005] Therefore, it is essential to research and develop a liquid carbon dioxide residual pressure power generation device. Summary of the Invention

[0006] This invention provides a liquid carbon dioxide residual pressure power generation device, which overcomes the shortcomings of the prior art. It can effectively solve the problems of high pressure liquid pressure energy waste and easy wear of pressure reducing valve in the existing low temperature methanol washing production, which in turn affects the stability of production.

[0007] The technical solution of this utility model is achieved through the following measures: a liquid carbon dioxide residual pressure power generation device, including a purification and separation unit, a liquefaction unit, and a pressure reduction power generation unit. The inlet of the purification and separation unit is fixedly connected to a first raw material conversion gas pipeline. The outlet of the purification and separation unit is fixedly connected to the inlet of the liquefaction unit, and a first desulfurization conversion gas pipeline is fixedly connected to the outlet of the purification and separation unit. A high-pressure liquid delivery pipeline is fixedly connected to the outlet of the liquefaction unit and the inlet of the pressure reduction power generation unit. The outlet of the pressure reduction power generation unit is fixedly connected to a carbon dioxide condensate pipeline.

[0008] The following are further optimizations and / or improvements to the above-mentioned utility model technical solution: The aforementioned pressure-reducing power generation unit includes a turbine, a generator, and a medium-pressure flash tank. A high-pressure liquid delivery pipeline is fixedly connected to the turbine inlet. The turbine is connected to the generator. A low-pressure liquid delivery pipeline is fixedly connected between the turbine outlet and the inlet of the medium-pressure flash tank. A carbon dioxide condensate pipeline is fixedly connected to the bottom outlet of the medium-pressure flash tank. A hydrogen recovery pipeline is fixedly connected to the top outlet of the medium-pressure flash tank.

[0009] A backup pipeline is fixedly connected between the high-pressure infusion pipeline and the low-pressure infusion pipeline, and a pressure reducing valve is fixedly installed on the backup pipeline.

[0010] The aforementioned purification and separation unit includes a raw gas cooler, a raw gas separator, and a scrubbing tower. The left inlet of the raw gas cooler is fixedly connected to a first raw gas conversion pipeline. The right outlet of the raw gas cooler is fixedly connected to a second raw gas conversion pipeline between the upper inlet of the raw gas separator. The top outlet of the raw gas separator is fixedly connected to a third raw gas conversion pipeline between the lower inlet of the scrubbing tower. The bottom outlet of the raw gas separator is fixedly connected to a first liquid phase pipeline. The upper inlet of the scrubbing tower is fixedly connected to a low-temperature methanol liquid pipeline. The top outlet of the scrubbing tower is fixedly connected to a purified tail gas pipeline.

[0011] The aforementioned scrubbing tower comprises upper and lower sections. The upper section is the decarbonization section, and the lower section is the desulfurization section. The outlet of the third feedstock conversion gas pipeline and the inlet of the first desulfurization conversion gas pipeline are both located on the desulfurization section. The first desulfurization conversion gas pipeline is located above the third feedstock conversion gas pipeline. The bottom outlet of the decarbonization section is fixedly connected to the first methanol liquid pipeline, and the bottom outlet of the desulfurization section is fixedly connected to the first methanol liquid pipeline via a second methanol liquid pipeline.

[0012] The aforementioned liquefaction unit includes a desulfurization shift gas cooler, an ammonia cooler, an evaporative heat exchanger, and a desulfurization shift gas separator. A first desulfurization shift gas pipeline is fixedly connected between the scrubbing tower and the right inlet of the desulfurization shift gas cooler. A second desulfurization shift gas pipeline is fixedly connected between the left outlet of the desulfurization shift gas cooler and the right inlet of the evaporative heat exchanger. A third desulfurization shift gas pipeline is fixedly connected between the left outlet of the evaporative heat exchanger and the right inlet of the desulfurization shift gas separator. A fourth desulfurization shift gas pipeline is fixedly connected between the top outlet of the desulfurization shift gas separator and the decarbonization section inlet of the scrubbing tower. A high-pressure liquid delivery pipeline is fixedly connected between the bottom outlet of the desulfurization shift gas separator and the turbine inlet. A fifth desulfurization shift gas pipeline is fixedly connected between the first and second desulfurization shift gas pipelines. An ammonia cooler is fixedly installed on the fifth desulfurization shift gas pipeline.

[0013] The bottom outlet of the aforementioned medium-pressure flash tank is fixedly connected to the lower inlet of the evaporator heat exchanger via a carbon dioxide condensate pipeline. The upper outlet of the evaporator heat exchanger is fixedly connected to the lower inlet of the raw material gas cooler via a first carbon dioxide gas pipeline. The upper outlet of the raw material gas cooler is fixedly connected to a second carbon dioxide gas pipeline.

[0014] A flow regulating valve is fixedly installed on the high-pressure liquid delivery pipeline between the aforementioned desulfurization shift gas separator and the standby pipeline; a first control valve is fixedly installed on the high-pressure liquid delivery pipeline between the standby pipeline and the turbine; and a second control valve is fixedly installed on the low-pressure liquid delivery pipeline between the turbine and the standby pipeline.

[0015] The above also includes a PLC controller. The turbine, generator, pressure reducing valve, flow regulating valve, first control valve, and second control valve are all electrically connected to the PLC controller.

[0016] This utility model has a reasonable and compact structure and is easy to use. Through the dual-path design of turbine + pressure reducing valve, combined with the automatic switching logic of controller, it ensures that if any path fails, the other path can be started immediately, avoiding interruption of liquid phase transportation and solving the problem of unstable fluid transportation. It utilizes the pressure energy of high-pressure liquid to convert the pressure energy of high-pressure liquid into mechanical energy, and then converts it into electrical energy through generator, realizing the recovery and utilization of pressure energy, while ensuring continuous and stable production. Attached Figure Description

[0017] Appendix Figure 1 This is a schematic diagram of the process flow of this utility model.

[0018] The codes in the attached diagram are as follows: 1 is the first feedstock shift gas pipeline, 2 is the first desulfurization shift gas pipeline, 3 is the high-pressure liquid delivery pipeline, 4 is the carbon dioxide condensate pipeline, 5 is the turbine, 6 is the generator, 7 is the medium-pressure flash tank, 8 is the low-pressure liquid delivery pipeline, 9 is the hydrogen recovery pipeline, 10 is the standby pipeline, 11 is the pressure reducing valve, 12 is the feedstock gas cooler, 13 is the feedstock gas separator, 14 is the scrubbing tower, 15 is the second feedstock shift gas pipeline, 16 is the third feedstock shift gas pipeline, 17 is the first liquid phase pipeline, 18 is the decarbonization section, 19 is the desulfurization section, 20 is the... 21 is a low-temperature methanol liquid pipeline, 22 is a purified tail gas pipeline, 23 is a first methanol liquid pipeline, 24 is a desulfurization shift gas cooler, 25 is an ammonia cooler, 26 is an evaporation heat exchanger, 27 is a desulfurization shift gas separator, 28 is a second desulfurization shift gas pipeline, 29 is a third desulfurization shift gas pipeline, 30 is a fourth desulfurization shift gas pipeline, 31 is a fifth desulfurization shift gas pipeline, 32 is a first carbon dioxide gas pipeline, 33 is a second carbon dioxide gas pipeline, 34 is a flow regulating valve, 35 is a first control valve, and 36 is a second control valve. Detailed Implementation

[0019] This utility model is not limited to the following embodiments, and the specific implementation method can be determined according to the technical solution of this utility model and the actual situation.

[0020] Unless otherwise specified, all equipment and devices used in this invention are existing, publicly known, and commonly used equipment and devices in the field.

[0021] In this utility model, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0022] The present invention will be further described below with reference to the embodiments and accompanying drawings: Example 1: As shown in the attached document Figure 1As shown, the liquid carbon dioxide residual pressure power generation device includes a purification and separation unit, a liquefaction unit, and a pressure-reducing power generation unit. The inlet of the purification and separation unit is fixedly connected to a first raw material conversion gas pipeline 1. The outlet of the purification and separation unit is fixedly connected to the inlet of the liquefaction unit via a first desulfurization conversion gas pipeline 2. The outlet of the liquefaction unit is fixedly connected to the inlet of the pressure-reducing power generation unit via a high-pressure liquid delivery pipeline 3. The outlet of the pressure-reducing power generation unit is fixedly connected to a carbon dioxide condensate pipeline 4.

[0023] In this invention, the feedstock shift gas from the syngas shift process, containing hydrogen, carbon dioxide, carbon monoxide, hydrogen sulfide, and small amounts of methane, nitrogen, and argon, is cooled, separated into gas and liquid, and desulfurized by a purification and separation unit to obtain desulfurized shift gas. The desulfurized shift gas enters the liquefaction unit, where it undergoes cooling and heat exchange, and gas-liquid separation to obtain a high-pressure liquid with a pressure of 5.75 MPa and a temperature of -32.8°C. The high-pressure liquid enters the pressure-reducing power generation unit via the high-pressure liquid delivery pipeline 3. The pressure-reducing power generation unit converts the pressure energy of the high-pressure liquid into mechanical energy, and then converts the mechanical energy into electrical energy, ultimately obtaining a low-pressure liquid rich in carbon dioxide with a pressure of 2.2 MPa and a temperature of -35.2°C. The low-pressure liquid rich in carbon dioxide is recycled to the upstream process via the carbon dioxide condensate pipeline 4.

[0024] The above-mentioned liquid carbon dioxide waste pressure power generation device can be further optimized and / or improved according to actual needs: Example 2: Its difference from Example 1 is as follows: (See attached) Figure 1 As shown, the reduced pressure power generation unit includes a turbine 5, a generator 6, and a medium-pressure flash tank 7. The turbine 5 is fixedly connected to a high-pressure liquid delivery line 3 at its inlet. The turbine 5 is connected to the generator 6. The turbine 5 is fixedly connected to a low-pressure liquid delivery line 8 between its outlet and the inlet of the medium-pressure flash tank 7. The bottom outlet of the medium-pressure flash tank 7 is fixedly connected to a carbon dioxide condensate line 4. The top outlet of the medium-pressure flash tank 7 is fixedly connected to a hydrogen recovery line 9.

[0025] As required, turbine 5 is a hydraulic turbine, a mechanical device that uses high-pressure fluid as the working medium for energy conversion. The main structural type of a hydraulic turbine is a centrifugal pump turbine, with the pump outlet being the turbine inlet and the pump inlet being the turbine outlet. Turbine 5 employs an impeller structure adapted to low temperatures (-32.8℃) and high pressures (5.75MPa). The high-pressure liquid drives the impeller to rotate, converting pressure energy into mechanical energy. The input shaft of generator 6 is coaxially connected to the main shaft of turbine 5, converting the impeller's mechanical energy into electrical energy. If the output is 380V AC, it can be directly connected to the power grid or used to power local equipment.

[0026] After the turbine 5 performs work, the high-pressure liquid pressure drops to 2.2 MPa and enters the medium-pressure flash tank 7 through the low-pressure liquid delivery pipeline 8 for flash separation. The flash separation yields recovered hydrogen and liquid carbon dioxide. The recovered hydrogen is sent to the production system through the hydrogen recovery pipeline 9, and the liquid carbon dioxide is transported to the cooling medium of the upstream process through the carbon dioxide condensate pipeline 4.

[0027] Example 3: Its difference from Examples 1 to 2 is as follows: (See attached) Figure 1 As shown, a spare pipeline 10 is fixedly connected between the high-pressure infusion pipeline 3 and the low-pressure infusion pipeline 8, and a pressure reducing valve 11 is fixedly installed on the spare pipeline 10.

[0028] As needed, pressure reducing valve 11 is connected in parallel with turbine 5. When turbine 5 fails or is under maintenance, high-pressure liquid enters backup pipeline 10 and is depressurized through pressure reducing valve 11 to ensure that high-pressure liquid can still be stably depressurized to the pressure required by medium-pressure flash tank 7, thus avoiding production interruption.

[0029] Example 4: Its difference from Examples 1 to 3 is as follows: (See attached) Figure 1 As shown, the purification and separation unit includes a raw gas cooler 12, a raw gas separator 13, and a scrubbing tower 14. The left inlet of the raw gas cooler 12 is fixedly connected to a first raw gas conversion pipeline 1. The right outlet of the raw gas cooler 12 is fixedly connected to the upper inlet of the raw gas separator 13 via a second raw gas conversion pipeline 15. The top outlet of the raw gas separator 13 is fixedly connected to the lower inlet of the scrubbing tower 14 via a third raw gas conversion pipeline 16. The bottom outlet of the raw gas separator 13 is fixedly connected to a first liquid phase pipeline 17. The upper inlet of the scrubbing tower 14 is fixedly connected to a low-temperature methanol liquid pipeline 20. The top outlet of the scrubbing tower 14 is fixedly connected to a purified tail gas pipeline 21.

[0030] As needed, the feed gas is cooled by the feed gas cooler 12 and then enters the feed gas separator 13 for gas-liquid separation. The liquid phase (methanol liquid containing water and CO2) obtained from the gas-liquid separation is transported to the subsequent methanol / water separation process by the first liquid phase pipeline 17. The gas phase obtained from the gas-liquid separation is transported to the scrubbing tower 14 by the third feed gas pipeline 16, where it is washed and purified by lean methanol liquid from the low-temperature methanol liquid pipeline 20. The feed gas is washed by the low-temperature methanol liquid at the top of the scrubbing tower 14, and the CO2 in the feed gas is removed to meet the purification requirements. The tail gas is led out by the top purification tail gas pipeline 21 and sent to the subsequent liquid nitrogen scrubbing unit. Part of the cold synthesis gas is returned from the liquid nitrogen scrubbing unit for heat exchange in the feed gas cooler 12.

[0031] Example 5: It differs from Examples 1 to 4 in that, as shown in the appendix... Figure 1As shown, the scrubbing tower 14 includes upper and lower sections. The upper section is the decarbonization section 18, and the lower section is the desulfurization section 19. The outlet of the third raw material conversion gas pipeline 16 and the inlet of the first desulfurization conversion gas pipeline 2 are both located on the desulfurization section 19. The first desulfurization conversion gas pipeline 2 is located above the third raw material conversion gas pipeline 16. The bottom outlet of the decarbonization section 18 is fixedly connected to the first methanol liquid pipeline 22, and the bottom outlet of the desulfurization section 19 is fixedly connected to the first methanol liquid pipeline 22 via a second methanol liquid pipeline 23.

[0032] As required, the core design structure of the low-temperature methanol washing desulfurization and decarbonization process includes a washing tower 14 and heat exchange equipment. Using cold methanol as the absorption solvent, it leverages the excellent solubility of methanol for acidic gases (CO2, H2S, COS, etc.) at low temperatures to remove acidic gases from the feed gas; this is a physical absorption method. In this invention, the removal of acidic gases from the feed gas is achieved using a low-temperature methanol washing process.

[0033] As required, the scrubbing tower 14 is configured with four sections. The bottom section (section A) of the scrubbing tower 14 is the desulfurization section 19, and the three upper sections of the scrubbing tower 14 (sections B, C and D from bottom to top) are the decarbonization sections 18. An intermediate cooler is provided between the decarbonization sections 18, and an intermediate heat exchanger is provided between the desulfurization sections 19.

[0034] In the desulfurization section 19, after removing H2S, COS, and some CO2 from the feedstock shift gas, desulfurized shift gas is obtained and sent out by the first desulfurization shift gas pipeline 2. After removing H2S and CO2, the sulfur-containing methanol-rich liquid from the bottom of the desulfurization section 19 of the scrubbing tower 14 is discharged by the second methanol liquid pipeline 23. After subsequent heat exchange, cooling, and depressurization, the dissolved H2 gas is separated by flash evaporation. Similarly, the sulfur-free methanol liquid from the bottom of the decarbonization section 18 of the scrubbing tower 14 is discharged by the first methanol liquid pipeline 22. After heat exchange, cooling, and depressurization, the dissolved H2 gas is separated by flash evaporation. The two flash gases are compressed and returned to the first feedstock shift gas pipeline 1.

[0035] Example 6: Its difference from Examples 1 to 5 is as follows: (See attached) Figure 1As shown, the liquefaction unit includes a desulfurization shift gas cooler 24, an ammonia cooler 25, an evaporation heat exchanger 26, and a desulfurization shift gas separator 27. A first desulfurization shift gas pipeline 2 is fixedly connected between the scrubbing tower 14 and the right inlet of the desulfurization shift gas cooler 24. A second desulfurization shift gas pipeline 28 is fixedly connected between the left outlet of the desulfurization shift gas cooler 24 and the right inlet of the evaporation heat exchanger 26. A third desulfurization shift gas pipeline 29 is fixedly connected between the left outlet of the evaporation heat exchanger 26 and the right inlet of the desulfurization shift gas separator 27. A fourth desulfurization shift gas pipeline 30 is fixedly connected between the top outlet of the desulfurization shift gas separator 27 and the inlet of the decarbonization section 18 of the scrubbing tower 14. A high-pressure liquid delivery pipeline 3 is fixedly connected between the bottom outlet of the desulfurization shift gas separator 27 and the inlet of the turbine 5. A fifth desulfurization shift gas pipeline 31 is fixedly connected between the first desulfurization shift gas pipeline 2 and the second desulfurization shift gas pipeline 28. An ammonia cooler 25 is fixedly installed on the fifth desulfurization shift gas pipeline 31.

[0036] As needed, a portion of the desulfurized shift gas enters the desulfurized shift gas cooler 24 via the first desulfurized shift gas pipeline 2, where it exchanges heat with the synthesis gas (returned by the subsequent liquid nitrogen washing unit), carbon dioxide, and tail gas generated within the production system to reduce its temperature, making full use of the cooling capacity generated within the system. Another portion of the desulfurized shift gas enters the ammonia cooler 25 via the fifth desulfurized shift gas pipeline 31 for cooling. Usually, both cooling devices are used simultaneously. When the cooling capacity within the system is insufficient, i.e., the outlet medium temperature of the desulfurized shift gas cooler 24 does not meet the requirements, the cooling capacity of the ammonia cooler 25 needs to be increased to provide additional cooling capacity and ensure that the medium entering the evaporative heat exchanger 26 is qualified. After being cooled by the desulfurization shift gas cooler 24 and the ammonia cooler 25, the desulfurization shift gas is mixed and enters the evaporation heat exchanger 26, where the temperature is further reduced. Finally, it enters the desulfurization shift gas separator 27 for solid-liquid separation. The separated gas phase is returned to section B of the scrubbing tower 14 via the fourth desulfurization shift gas pipeline 30 for further scrubbing. The carbon dioxide condensate (high-pressure liquid with a pressure of 5.75 MPa and a temperature of -32.8℃) separated from the desulfurization shift gas separator 27 enters the turbine 5 along the high-pressure liquid delivery pipeline 3.

[0037] As required, the ammonia cooler 25 mainly consists of a refrigerant circulation system, a lubricating oil circulation system, a cooling water circulation system, and a refrigerant circulation system. The ammonia cooler 25 uses ammonia as a refrigerant and works mainly based on the principle of heat exchange. It utilizes the heat absorption property of liquid ammonia evaporation to cool other media.

[0038] Example 7: Its difference from Examples 1 to 6 is as follows: (See attached) Figure 1As shown, the bottom outlet of the medium-pressure flash tank 7 is fixedly connected to the lower inlet of the evaporator heat exchanger 26 via a carbon dioxide condensate pipeline 4. The upper outlet of the evaporator heat exchanger 26 is fixedly connected to the lower inlet of the raw material gas cooler 12 via a first carbon dioxide gas pipeline 32. The upper outlet of the raw material gas cooler 12 is fixedly connected to a second carbon dioxide gas pipeline 33.

[0039] As needed, the liquid carbon dioxide separated by flash evaporation in the medium-pressure flash tank 7 is transported to the evaporation heat exchanger 26 via the carbon dioxide condensate pipeline 4. After evaporation and heat exchange with the desulfurization change gas, it is vaporized into high-pressure carbon dioxide gas. After heat exchange in the raw material gas cooler 12, the high-pressure carbon dioxide gas is sent out of the boundary area along the second carbon dioxide gas pipeline 33.

[0040] Example 8: It differs from Examples 1 to 7 in that: as shown in the appendix Figure 1 As shown, a flow regulating valve 34 is fixedly installed on the high-pressure liquid delivery pipeline 3 between the desulfurization shift gas separator 27 and the standby pipeline 10, a first control valve 35 is fixedly installed on the high-pressure liquid delivery pipeline 3 between the standby pipeline 10 and the turbine 5, and a second control valve 36 is fixedly installed on the low-pressure liquid delivery pipeline 8 between the turbine 5 and the standby pipeline 10.

[0041] Example 9: It differs from Examples 1 to 8 in that: as shown in the appendix Figure 1 As shown, it also includes a PLC controller. The turbine 5, generator 6, pressure reducing valve 11, flow regulating valve 34, first control valve 35, and second control valve 36 are all electrically connected to the PLC controller.

[0042] As needed, the first control valve 35 at the inlet of turbine 5 and the second control valve 36 at the outlet of turbine 5 form the main control path (turbine power generation path), while the flow regulating valve 34 and the pressure reducing valve 11 form the backup pressure reduction path. When the main path is operating normally and the pressures of the high-pressure infusion pipeline 3 and the low-pressure infusion pipeline 8 are stable, the flow regulating valve 34, the first control valve 35, and the second control valve 36 are opened, and the pressure reducing valve 11 is closed. The high-pressure liquid enters the medium-pressure flash tank 7 after being generated by the turbine 5. When the turbine 5 speed is abnormal, the generator 6 malfunctions, or the main path pressure changes suddenly, the first control valve 35 and the second control valve 36 are immediately closed, and the pressure reducing valve 11 is opened simultaneously to switch to the backup pressure reduction path. The pressure reducing valve 11 is used to reduce the pressure of the high-pressure liquid, ensuring that the liquid phase is continuously delivered to the medium-pressure flash tank 7.

[0043] Depending on the needs, the pipelines and equipment of this liquid carbon dioxide residual pressure power generation unit may also be equipped with conventional valves, thermometers, and pressure gauges known in the art, according to production requirements. The PLC controller can be a Siemens S7-1500, which is equipped with a Yokogawa CS3000 DCS control system.

[0044] Before and after comparison: The liquid turbine directly utilizes the pressure difference between 5.75 MPa and 2.2 MPa to convert the pressure energy of the high-pressure liquid into mechanical energy, which is then converted into electrical energy by generator 6. According to the principle of energy conservation, the output power of the turbine can be estimated by the formula: P = Q × ΔP × η (where: Q is the liquid flow rate (m³ / h), ΔP is the pressure difference (MPa), and η is the turbine efficiency (approximately 0.7 to 0.8)).

[0045] In this invention, the liquid phase volumetric flow rate is approximately 134 m³ / h, and the recoverable power is approximately 99.1 kW, directly solving the energy dissipation problem of the traditional pressure reducing valve 11.

[0046] The above technical features constitute various embodiments of this utility model, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0047] The usage process of this utility model is as follows: First, the feedstock shift gas from the shift process is cooled by the feedstock gas cooler 12 and then enters the feedstock gas separator 13 for gas-liquid separation. The resulting gaseous feedstock shift gas enters the scrubbing tower 14 through the third feedstock shift gas pipeline 16. In the scrubbing tower 14, the feedstock shift gas undergoes desulfurization and decarbonization to obtain desulfurized shift gas. Next, the desulfurized shift gas is cooled by the desulfurized shift gas cooler 24 and the ammonia cooler 25, and then further cooled by the evaporation heat exchanger 26 before entering the desulfurized shift gas separator 27. Gas-liquid separation is performed to obtain high-pressure carbon dioxide liquid. Finally, the high-pressure carbon dioxide liquid enters the turbine 5 through the high-pressure liquid delivery pipeline 3. The turbine 5 converts the pressure energy of the high-pressure carbon dioxide liquid into mechanical energy, and then the mechanical energy is converted into electrical energy through the generator 6. After the high-pressure carbon dioxide liquid does work through the turbine 5, the resulting low-pressure liquid rich in carbon dioxide is flashed and separated to recover hydrogen in the medium-pressure flash tank 7. Then, it passes through the evaporation heat exchanger 26 and the raw material gas cooler 12 for heat exchange, and is vaporized to obtain high-pressure CO2 product gas, which is then sent out of the boundary area.

Claims

1. A liquid carbon dioxide residual pressure power generation device, characterized in that... It includes a purification and separation unit, a liquefaction unit, and a pressure-reducing power generation unit. The inlet of the purification and separation unit is fixedly connected to a first raw material conversion gas pipeline. The outlet of the purification and separation unit is fixedly connected to the inlet of the liquefaction unit, and a first desulfurization conversion gas pipeline is fixedly connected to the outlet of the liquefaction unit and the inlet of the pressure-reducing power generation unit. The outlet of the pressure-reducing power generation unit is fixedly connected to a carbon dioxide condensate pipeline.

2. The liquid carbon dioxide residual pressure power generation device according to claim 1, characterized in that... The reduced pressure power generation unit includes a turbine, a generator, and a medium-pressure flash tank. The turbine inlet is fixedly connected to a high-pressure liquid delivery pipeline. The turbine is connected to the generator. The turbine outlet is fixedly connected to the inlet of the medium-pressure flash tank via a low-pressure liquid delivery pipeline. The bottom outlet of the medium-pressure flash tank is fixedly connected to a carbon dioxide condensate pipeline. The top outlet of the medium-pressure flash tank is fixedly connected to a hydrogen recovery pipeline.

3. The liquid carbon dioxide residual pressure power generation device according to claim 2, characterized in that... A backup pipeline is fixedly connected between the high-pressure infusion pipeline and the low-pressure infusion pipeline, and a pressure reducing valve is fixedly installed on the backup pipeline.

4. The liquid carbon dioxide residual pressure power generation device according to claim 1 or 2, characterized in that... The purification and separation unit includes a raw gas cooler, a raw gas separator, and a scrubbing tower. The left inlet of the raw gas cooler is fixedly connected to a first raw gas conversion pipeline. The right outlet of the raw gas cooler is fixedly connected to a second raw gas conversion pipeline between the upper inlet of the raw gas separator. The top outlet of the raw gas separator is fixedly connected to a third raw gas conversion pipeline between the lower inlet of the scrubbing tower. The bottom outlet of the raw gas separator is fixedly connected to a first liquid phase pipeline. The upper inlet of the scrubbing tower is fixedly connected to a low-temperature methanol liquid pipeline. The top outlet of the scrubbing tower is fixedly connected to a purified tail gas pipeline.

5. The liquid carbon dioxide residual pressure power generation device according to claim 4, characterized in that... The scrubbing tower consists of two sections: an upper section for decarbonization and a lower section for desulfurization. The outlet of the third feedstock conversion gas pipeline and the inlet of the first desulfurization conversion gas pipeline are both located on the desulfurization section. The first desulfurization conversion gas pipeline is located above the third feedstock conversion gas pipeline. The bottom outlet of the decarbonization section is fixedly connected to the first methanol liquid pipeline, and the bottom outlet of the desulfurization section is fixedly connected to the first methanol liquid pipeline via a second methanol liquid pipeline.

6. The liquid carbon dioxide residual pressure power generation device according to claim 4, characterized in that... The liquefaction unit includes a desulfurization shift gas cooler, an ammonia cooler, an evaporative heat exchanger, and a desulfurization shift gas separator. A first desulfurization shift gas pipeline is fixedly connected between the scrubbing tower and the right inlet of the desulfurization shift gas cooler. A second desulfurization shift gas pipeline is fixedly connected between the left outlet of the desulfurization shift gas cooler and the right inlet of the evaporative heat exchanger. A third desulfurization shift gas pipeline is fixedly connected between the left outlet of the evaporative heat exchanger and the right inlet of the desulfurization shift gas separator. A fourth desulfurization shift gas pipeline is fixedly connected between the top outlet of the desulfurization shift gas separator and the decarbonization section inlet of the scrubbing tower. A high-pressure liquid delivery pipeline is fixedly connected between the bottom outlet of the desulfurization shift gas separator and the turbine inlet. A fifth desulfurization shift gas pipeline is fixedly connected between the first and second desulfurization shift gas pipelines. An ammonia cooler is fixedly installed on the fifth desulfurization shift gas pipeline.

7. The liquid carbon dioxide residual pressure power generation device according to claim 5, characterized in that... The liquefaction unit includes a desulfurization shift gas cooler, an ammonia cooler, an evaporative heat exchanger, and a desulfurization shift gas separator. A first desulfurization shift gas pipeline is fixedly connected between the scrubbing tower and the right inlet of the desulfurization shift gas cooler. A second desulfurization shift gas pipeline is fixedly connected between the left outlet of the desulfurization shift gas cooler and the right inlet of the evaporative heat exchanger. A third desulfurization shift gas pipeline is fixedly connected between the left outlet of the evaporative heat exchanger and the right inlet of the desulfurization shift gas separator. A fourth desulfurization shift gas pipeline is fixedly connected between the top outlet of the desulfurization shift gas separator and the decarbonization section inlet of the scrubbing tower. A high-pressure liquid delivery pipeline is fixedly connected between the bottom outlet of the desulfurization shift gas separator and the turbine inlet. A fifth desulfurization shift gas pipeline is fixedly connected between the first and second desulfurization shift gas pipelines. An ammonia cooler is fixedly installed on the fifth desulfurization shift gas pipeline.

8. The liquid carbon dioxide residual pressure power generation device according to claim 6 or 7, characterized in that... The bottom outlet of the medium-pressure flash tank is fixedly connected to the lower inlet of the evaporator heat exchanger via a carbon dioxide condensate pipeline. The upper outlet of the evaporator heat exchanger is fixedly connected to the lower inlet of the raw material gas cooler via a first carbon dioxide gas pipeline. The upper outlet of the raw material gas cooler is fixedly connected to a second carbon dioxide gas pipeline.

9. The liquid carbon dioxide residual pressure power generation device according to claim 8, characterized in that... A flow regulating valve is fixedly installed on the high-pressure liquid delivery pipeline between the desulfurization shift gas separator and the standby pipeline; a first control valve is fixedly installed on the high-pressure liquid delivery pipeline between the standby pipeline and the turbine; and a second control valve is fixedly installed on the low-pressure liquid delivery pipeline between the turbine and the standby pipeline.

10. The liquid carbon dioxide residual pressure power generation device according to claim 9, characterized in that... It also includes a PLC controller, and the turbine, generator, pressure reducing valve, flow regulating valve, first control valve, and second control valve are all electrically connected to the PLC controller.

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