Normal-temperature adsorption liquid nitrogen washing device with expansion machine
By adopting expansion refrigeration technology in the room temperature adsorption liquid nitrogen washing device, the problem of insufficient cooling capacity is solved, and efficient purification of synthesis gas and low-energy production is achieved.
Patent Information
- Application Number
- CN202420522419.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-18
- Publication Date
- 2025-03-25
- Estimated Expiration
- 2034-03-18
AI Technical Summary
The room temperature adsorption liquid nitrogen washing device has insufficient cooling capacity, which cannot reach the low temperature required for purification of the liquid nitrogen washing device, resulting in the CO content in the synthesis gas that does not meet the standards and cannot meet the needs of subsequent processes.
The rear-end expansion and refrigeration method is adopted to expand and cool the low-pressure nitrogen gas through the expander to replenish the cooling capacity of the liquid nitrogen washing box unit, avoiding the replenishment of liquid nitrogen and reducing energy consumption.
Effective purification of coal-to-synthesis gas for room temperature is achieved, and synthesis gas with a CO content of less than 1 ppm is produced, reducing the investment cost and energy consumption of the device.
Smart Images
Figure CN222658243U_ABST
Abstract
Description
Technical Field
[0001] The utility model designs a normal temperature adsorption liquid nitrogen washing device with an expander, belonging to the field of low temperature gas separation. Background Art
[0002] Ammonia has a wide range of uses and is one of the most produced inorganic compounds in the world. It can be used as a refrigerant itself, and as a basic chemical raw material, it is widely used in industries such as nitrogen fertilizer, nitric acid, ammonium salts and soda ash.
[0003] The raw materials for synthetic ammonia include natural gas, naphtha, heavy oil and coal, etc. Coal is converted into ammonia synthesis gas through gasification, conversion, purification, compression and other devices to provide raw gas for the synthetic ammonia device.
[0004] Liquid nitrogen washing device is a technology for final purification of crude synthesis gas. It is mainly used to remove trace components such as CO and CH4 in crude synthesis gas, and also nitrogenizes the synthesis gas to meet the requirements of the ratio of H2 and N2 for ammonia synthesis. The principle of its purification is: use liquefied high-pressure nitrogen to wash the raw gas in the nitrogen washing tower, so as to remove trace components such as CO in the crude synthesis gas. The cooling loss of the liquid nitrogen washing device (i.e., heat transfer temperature difference loss and cooling loss) is compensated by the cooling effect generated by the Joule-Thomson effect during the nitrogenization process of the raw gas. When the pressure of high-pressure nitrogen is low, the cooling generated by the Joule-Thomson effect is not enough to compensate for the cooling loss, and the insufficient cooling must be supplemented by liquid nitrogen evaporation. This purification method has the characteristics of high purification degree of the synthesis gas (such as CO content of about 1ppm) and low operating cost. However, there are more and more room temperature adsorption liquid nitrogen washing devices. Compared with previous liquid nitrogen washing devices, room temperature liquid nitrogen washing devices have insufficient cooling capacity and cannot reach the low temperature required for liquid nitrogen washing devices to purify. As a result, the CO content in the produced synthesis gas does not meet the standards and cannot meet the needs of subsequent processes, let alone recovery and comprehensive utilization.
[0005] The liquid nitrogen washing and purification synthesis gas device of the utility model adopts a rear-end expansion refrigeration method to compensate for the insufficient cooling capacity of the liquid nitrogen washing device for the working condition that the raw gas from the upstream is at room temperature, thereby providing a new process selection route for the construction of the liquid nitrogen washing device. Summary of the invention
[0006] The purpose of the utility model is to purify and nitrogenize the normal temperature coal-based synthesis gas from the upstream to produce a synthesis gas with a hydrogen-nitrogen ratio of 3:1, and provide a deep cold separation device and method for the raw gas for the downstream ammonia synthesis device. The raw gas enters the liquid nitrogen washing boundary area at normal temperature, and the equipment, pipelines, switching valves, etc. of the molecular sieve part can be made of carbon steel, which reduces the investment cost of the device; the defect of insufficient process cooling capacity is avoided by the expansion refrigeration method, and the device is avoided from replenishing liquid nitrogen, and the laying of liquid nitrogen vacuum pipelines is reduced; the expansion machine is equipped with a generator to achieve expansion power generation and send out a certain amount of energy; the ammonia synthesis gas separated by the liquid nitrogen washing cold box has a hydrogen-nitrogen ratio of 3:1, and the contents of CO and CH4 are both less than 1ppm, and the three heat exchangers in the cold box of the conventional liquid nitrogen washing device are combined into two, which reduces the complexity of the piping in the cold box, reduces the pressure loss of the process gas in the device, and reduces energy consumption.
[0007] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a room temperature adsorption liquid nitrogen washing device with an expander, the device comprising a molecular sieve adsorption unit, an expansion unit, and a liquid nitrogen cold washing box unit. The molecular sieve adsorption unit is connected to the coal-based synthesis gas from upstream through a pipeline, and the molecular sieve is filled in the molecular sieve adsorption unit to adsorb carbon dioxide, methanol, water and other components that are easy to solidify at low temperatures in the mixed gas to prevent these substances from freezing the pipeline and equipment. The molecular sieve adsorption unit is connected to the liquid nitrogen cold washing box unit at the rear. The expansion unit is connected to the low-pressure nitrogen from the liquid nitrogen cold washing box through a pipeline, and returns to the liquid nitrogen cold washing box unit through the pipeline after expansion.
[0008] Preferably, the molecular sieve adsorption unit comprises: a molecular sieve adsorber, a regeneration gas heater, and a regeneration gas cooler, which are connected to each other through pipelines. The coal-based synthesis gas from the upstream enters the molecular sieve adsorber through the first pipeline to adsorb and remove CO2, methanol, and water, and then exits the molecular sieve adsorption unit through the second pipeline and enters the liquid nitrogen washing cold box unit.
[0009] Preferably, the liquid nitrogen cold box washing unit comprises: a first main heat exchanger, a second main heat exchanger, a nitrogen washing tower, a hydrogen separator, and a gas mixer; wherein a total of 7 flow channels are arranged in the first main heat exchanger, and a total of 5 flow channels are arranged in the second main heat exchanger, the second pipeline is connected with the first flow channel 1A of the first main heat exchanger, and is connected with the eighth flow channel 2A of the second main heat exchanger through the third pipeline after being cooled in the first flow channel 1A, and enters the lower part of the nitrogen washing tower through the fourth pipeline after being cooled in the eighth flow channel 2A; the second flow channel 1B of the first main heat exchanger is connected with the high-pressure nitrogen in the boundary area through the fifth pipeline, and is cooled in the second flow channel 1B and then exits the first main heat exchanger through the sixth pipeline, and then is divided into the thirteenth pipeline and the seventh pipeline, the thirteenth pipeline enters the gas mixer for rough nitrogen preparation, the seventh pipeline is connected with the ninth flow channel 2B of the second main heat exchanger, and is cooled in the ninth flow channel 2B and enters the upper part of the nitrogen washing tower through the eighth pipeline.
[0010] Preferably, the top of the nitrogen scrubber is connected to the eleventh flow channel 2D of the second main heat exchanger through the ninth pipeline, enters the gas mixer through the tenth pipeline after being reheated in the eleventh flow channel 2D, and then connected to the fourth flow channel 1D of the first main heat exchanger through the eleventh pipeline, and exits the boundary area through the twelfth pipeline after being reheated to room temperature in the fourth flow channel 1D;
[0011] Preferably, the bottom of the nitrogen washing tower is connected with the hydrogen separator through the seventeenth pipeline, and gas and liquid are separated in the hydrogen separator, wherein the top of the hydrogen separator is connected with the twelfth flow channel 2E of the second main heat exchanger through the eighteenth pipeline, and is connected with the fifth flow channel 1E of the first main heat exchanger through the nineteenth pipeline after being reheated in the twelfth flow channel 2E, and is reheated to room temperature in the fifth flow channel 1E and then passes through the twentieth pipeline to exit the boundary area; the bottom of the hydrogen separator is connected with the tenth flow channel 2C of the second main heat exchanger through the twenty-first pipeline, and is connected with the third flow channel 1C of the first main heat exchanger through the twenty-second pipeline after being reheated in the tenth flow channel 2C, and is reheated to room temperature in the third flow channel 1C and then passes through the twenty-third pipeline to exit the boundary area.
[0012] Preferably, the sixth flow channel 1F of the first main heat exchanger is connected to the low-pressure nitrogen from the external boundary area through the twenty-fourth pipeline, and after being cooled in the sixth flow channel 1F, it exits the first main heat exchanger through the twenty-fifth pipeline, and enters the expansion unit through the twenty-fifth pipeline, and after expansion, it returns to the liquid nitrogen washing cold box unit through the twenty-sixth pipeline, and is connected to the seventh flow channel 1G of the first main heat exchanger through the twenty-sixth pipeline, and after being reheated in the seventh flow channel 1G, it exits the first main heat exchanger through the twenty-seventh pipeline and out of the boundary area.
[0013] Preferably, the expansion unit is composed of an expander; liquid nitrogen enters the expansion unit through the twenty-fifth pipeline from the liquid nitrogen cold washing box, exits the expansion unit through the twenty-sixth pipeline after expansion, and is sent back to the liquid nitrogen cold washing box; the expansion drives the generator to generate electricity to be transmitted out of the expansion unit.
[0014] The positive effect of the utility model is that the raw gas in the molecular sieve adsorption unit is at room temperature, the operating conditions of the molecular sieve adsorption unit become mild, the laying of low-temperature pipelines is reduced, and all equipment, pipelines (including pipe fittings), valves, etc. can be made of carbon steel, reducing the investment cost of the device.
[0015] The positive effect of the utility model is that in the above-mentioned liquid nitrogen washing cold box unit, the raw gas enters the plate-fin heat exchanger in the liquid nitrogen washing cold box unit at room temperature, which reduces the risk of damage to the heat exchanger due to excessive temperature difference at the end surface of the plate-fin heat exchanger during operation (especially during the start-up process). At the same time, compared with the cold box of the liquid nitrogen washing device for conventional low-temperature raw gas, the plate-fin heat exchangers in the heat exchanger are merged from 3 to 2, which reduces the complexity of the piping in the cold box, reduces the pressure loss of the process gas in the equipment, and indirectly reduces energy consumption.
[0016] The positive effect of the utility model is that in the above-mentioned liquid nitrogen cold box washing unit, when the raw gas enters the liquid nitrogen cold box washing unit at room temperature, the cooling capacity of the device is insufficient. Normally, a certain amount of liquid nitrogen (about -180°C) needs to be introduced from the air separation through a vacuum pipeline to the cold box to supplement the cooling capacity. The utility model expands and cools the low-pressure nitrogen to a certain temperature through an expansion unit, which can meet the cooling capacity demand of the liquid nitrogen cold box washing unit. At the same time, the expansion unit can adjust the pre-cooling temperature in time according to the actual operating conditions of the liquid nitrogen cold box washing unit to ensure the stable operation of the liquid nitrogen cold box washing unit. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION
[0018] The utility model will be described in detail below with reference to the accompanying drawings: Figure 1 As shown, a room temperature adsorption liquid nitrogen washing device with an expander can purify room temperature coal-based synthesis gas from upstream, produce ammonia synthesis gas with a hydrogen-nitrogen ratio of 3:1 and a CO content of less than 1ppm, and provide raw gas for a downstream ammonia synthesis device. The device includes a molecular sieve adsorption unit 100, an expansion unit 101, and a liquid nitrogen washing cold box unit 102. The molecular sieve adsorption unit 100 is connected to the coal-based synthesis gas from upstream through a pipeline. The molecular sieve adsorption unit 100 includes: an S1 molecular sieve adsorber, an E1 regeneration gas heater, and an E2 regeneration gas cooler; the S1 molecular sieve adsorber, the E1 regeneration gas heater, and the E2 regeneration gas cooler are mainly used to adsorb dihydrogen in the mixed gas. Carbon dioxide, methanol, water and other components that are easy to solidify at low temperatures are prevented from freezing pipelines and equipment; the expansion unit includes: an expander K1, which mainly uses the low-pressure nitrogen from the expansion refrigeration air separation; the liquid nitrogen washing cold box unit includes: a first main heat exchanger E3, a second main heat exchanger E4, a nitrogen washing tower T1, a hydrogen separator D1, and a mixer M1, which mainly purifies the CO content in the raw gas to below 1ppm and nitrogen is added to the purified synthesis gas at the same time, wherein the first main heat exchanger E3 is provided with 1A, 1B, 1C, 1D, 1E, 1F, 1G, a total of 7 flow channels, and the second main heat exchanger E4 is provided with 2A, 2B, 2C, 2D, 2E, a total of 5 flow channels.
[0019] The raw gas containing H2 ≥ 90% from the upstream device enters the molecular sieve adsorption unit 100 through the first pipeline 01, and after adsorbing and removing CO2, methanol and water, it leaves the molecular sieve adsorption unit 100 through the second pipeline 02 and enters the liquid nitrogen washing cold box unit;
[0020] The low-pressure nitrogen from the outer boundary area enters the liquid nitrogen washing cold box unit through the twenty-fourth pipeline 24, enters the expansion unit through the twenty-fifth pipeline 25 for expansion after cooling, and is sent back to the liquid nitrogen washing cold box through the twenty-sixth pipeline 26 after expansion;
[0021] The raw gas from the molecular sieve adsorption unit 100 is connected to the first flow channel 1A of the first main heat exchanger E3 through the second pipeline 02, and is connected to the eighth flow channel 2A of the second main heat exchanger E4 through the third pipeline 03 after being cooled in the first flow channel 1A. After being cooled in the eighth flow channel 2A, it enters the lower part of the nitrogen washing tower T1 through the fourth pipeline 04; the high-pressure nitrogen from the expansion unit is connected to the second flow channel 1B of the first main heat exchanger E3 through the fifth pipeline 05, and is cooled in the second flow channel 1B. After passing through the sixth pipeline 05, it exits the second main heat exchanger E4, and then is divided into the thirteenth pipeline 13 and the seventh pipeline 7. The thirteenth pipeline 13 enters the gas mixer M1, and the seventh pipeline 07 is connected to the ninth flow channel 2B of the second main heat exchanger E4. After being cooled in the ninth flow channel 2B, it enters the upper part of the nitrogen washing tower T1 through the eighth pipeline 08;
[0022] The top of the nitrogen washing tower T1 is connected to the eleventh flow channel 2D of the second main heat exchanger E4 through the ninth pipeline 09, and after being reheated in the eleventh flow channel 2D, it enters the gas mixer M1 through the tenth pipeline 10, and then is connected to the fourth flow channel 1D of the first main heat exchanger E3 through the eleventh pipeline 11, and after being reheated to room temperature in the fourth flow channel 1D, it passes through the twelfth pipeline 12 out of the boundary area; the tower kettle of the nitrogen washing tower T1 is connected to the hydrogen separator D1 through the seventeenth pipeline 17, and gas and liquid are separated in the hydrogen separator D1, wherein the top of the hydrogen separator D1 is connected to the second main The twelfth flow channel 2E of the heat exchanger E5 is connected, and after being reheated in the twelfth flow channel 2E, it is connected to the fifth flow channel 1E of the first main heat exchanger E4 through the nineteenth pipeline 19, and after being reheated to normal temperature in the flow channel 19, it passes through the twentieth pipeline 20 to exit the boundary area; the bottom of the hydrogen separator D1 is connected to the tenth flow channel 2C of the second main heat exchanger E5 through the twenty-first pipeline 21, and after being reheated in the tenth flow channel 2C, it is connected to the third flow channel 1C of the first main heat exchanger E4 through the twenty-second pipeline 22, and after being reheated to normal temperature in the third flow channel 1C, it passes through the twenty-third pipeline 23 to exit the boundary area. The low-pressure nitrogen from the external boundary area is connected with the sixth flow channel 1F of the first main heat exchanger E3 through the twenty-fourth pipeline 24, and after being cooled in the sixth flow channel 1F, it exits the first main heat exchanger E3 through the twenty-fifth pipeline 25, and enters the expansion unit through the twenty-fifth pipeline 25, and after expansion, it returns to the liquid nitrogen washing cold box unit through the twenty-sixth pipeline 26, and is connected with the seventh flow channel 1G of the first main heat exchanger E3 through the twenty-sixth pipeline 26, and after being reheated in the seventh flow channel 1G, it exits the first main heat exchanger E3 and the boundary area through the twenty-seventh pipeline 27.
[0023] The above embodiments are specific implementations of the present utility model. A variety of equivalent combinations or changes can be made to a room temperature adsorption liquid nitrogen washing device and method with expansion refrigeration, all of which belong to the protection scope of the present utility model.
Claims
1. A room temperature adsorption liquid nitrogen washing device with an expander, the device comprises a molecular sieve adsorption unit, an expansion unit, and a liquid nitrogen washing cold box unit, characterized in that: The molecular sieve adsorption unit is connected to the coal-based synthesis gas from upstream through a pipeline. The molecular sieve is filled in the molecular sieve adsorption unit to adsorb carbon dioxide, methanol and water in the mixed gas to prevent these substances from freezing the pipeline and equipment. The molecular sieve adsorption unit is connected to the liquid nitrogen cold washing box unit at the rear. The expansion unit is connected to the low-pressure nitrogen from the liquid nitrogen cold washing box through a pipeline, and returns to the liquid nitrogen cold washing box unit through a pipeline after expansion.
2. The room temperature adsorption liquid nitrogen washing device with an expander according to claim 1, characterized in that: The molecular sieve adsorption unit includes: a molecular sieve adsorber, a regeneration gas heater, and a regeneration gas cooler, which are connected to each other through pipelines. The coal-based synthesis gas from the upstream enters the molecular sieve adsorber through a first pipeline to adsorb and remove CO2, methanol, and water, and then exits the molecular sieve adsorption unit through a second pipeline and enters a liquid nitrogen washing cold box unit.
3. The room temperature adsorption liquid nitrogen washing device with an expander according to claim 2 is characterized in that: The liquid nitrogen cold box washing unit comprises: a first main heat exchanger, a second main heat exchanger, a nitrogen washing tower, a hydrogen separator, and a gas mixer; wherein the first main heat exchanger is provided with a total of 7 flow channels, and the second main heat exchanger is provided with a total of 5 flow channels; the second pipeline is connected with the first flow channel (1A) of the first main heat exchanger, and after being cooled in the first flow channel (1A), is connected with the eighth flow channel (2A) of the second main heat exchanger through the third pipeline, and after being cooled in the eighth flow channel (2A), enters the lower part of the nitrogen washing tower through the fourth pipeline; the second flow channel (1B) of the first main heat exchanger is connected with the high-pressure nitrogen in the boundary area through the fifth pipeline, and after being cooled in the second flow channel (1B), exits the first main heat exchanger through the sixth pipeline, and then is divided into the thirteenth pipeline and the seventh pipeline, the thirteenth pipeline enters the gas mixer for rough nitrogen preparation, and the seventh pipeline is connected with the ninth flow channel (2B) of the second main heat exchanger, and after being cooled in the ninth flow channel (2B), enters the upper part of the nitrogen washing tower through the eighth pipeline.
4. The room temperature adsorption liquid nitrogen washing device with an expander according to claim 3 is characterized in that: The top of the nitrogen washing tower is connected to the eleventh flow channel (2D) of the second main heat exchanger through the ninth pipeline, and after being reheated in the eleventh flow channel (2D), it enters the gas mixer through the tenth pipeline, and then is connected to the fourth flow channel (1D) of the first main heat exchanger through the eleventh pipeline, and after being reheated to room temperature in the fourth flow channel (1D), it exits the boundary area through the twelfth pipeline.
5. The room temperature adsorption liquid nitrogen washing device with an expander according to claim 4 is characterized in that: The bottom of the nitrogen washing tower is connected to the hydrogen separator through the seventeenth pipeline, and gas and liquid are separated in the hydrogen separator, wherein the top of the hydrogen separator is connected to the twelfth flow channel (2E) of the second main heat exchanger through the eighteenth pipeline, and after being reheated in the twelfth flow channel (2E), it is connected to the fifth flow channel (1E) of the first main heat exchanger through the nineteenth pipeline, and after being reheated to room temperature in the fifth flow channel (1E), it passes through the twentieth pipeline to exit the boundary area; the bottom of the hydrogen separator is connected to the tenth flow channel (2C) of the second main heat exchanger through the twenty-first pipeline, and after being reheated in the tenth flow channel (2C), it is connected to the third flow channel (1C) of the first main heat exchanger through the twenty-second pipeline, and after being reheated to room temperature in the third flow channel (1C), it passes through the twenty-third pipeline to exit the boundary area.
6. The room temperature adsorption liquid nitrogen washing device with an expander according to claim 5, characterized in that: The sixth flow channel (1F) of the first main heat exchanger is connected to the low-pressure nitrogen from the external boundary area through the twenty-fourth pipeline, and after being cooled in the sixth flow channel (1F), it exits the first main heat exchanger through the twenty-fifth pipeline, and enters the expansion unit through the twenty-fifth pipeline, and after expansion, it returns to the liquid nitrogen washing cold box unit through the twenty-sixth pipeline, and is connected to the seventh flow channel (1G) of the first main heat exchanger through the twenty-sixth pipeline, and after being reheated in the seventh flow channel (1G), it exits the first main heat exchanger through the twenty-seventh pipeline and out of the boundary area.
7. The room temperature adsorption liquid nitrogen washing device with an expander according to claim 6, characterized in that: The expansion unit is composed of an expander; liquid nitrogen enters the expansion unit through the twenty-fifth pipeline from the liquid nitrogen cold washing box, exits the expansion unit through the twenty-sixth pipeline after expansion, and is sent back to the liquid nitrogen cold washing box; the expansion drives the generator to generate electricity and transmit it out of the expansion unit.