A liquid ammonia cooling capacity recovery and utilization device
By designing a liquid ammonia cooling energy recovery and utilization device, the problems of high liquid ammonia cold source temperature and cooling energy waste were solved, achieving effective cooling energy recovery and stable equipment operation, and reducing the load on the ammonia ice machine.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- MINGSHUI CHEM FERTILIZER PLANT
- Filing Date
- 2025-05-30
- Publication Date
- 2026-05-26
AI Technical Summary
In the high-pressure ammonia synthesis process using hydrogen and nitrogen, the high temperature of the liquid ammonia cold source leads to a waste of cooling capacity, the ammonia ice machine is under heavy load, and the direct delivery of low-temperature liquid ammonia to the secondary flash tank also results in a waste of cooling capacity.
Design a liquid ammonia cold energy recovery and utilization device. The low-temperature liquid ammonia from the outlet of the primary flash tank exchanges heat with the high-temperature liquid ammonia from the liquid ammonia storage tank. After the temperature is reduced, it is used as a cold source. The ammonia absorbs heat from the synthesis gas in the ammonia cooler, raises the temperature, and is then sent to the secondary flash tank for further flashing.
It recovers the cold energy of cryogenic liquid ammonia, saves energy, reduces the load on the ammonia ice machine, and ensures long-term stable operation of the equipment, thus having good practical value.
Smart Images
Figure CN224285050U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of synthetic ammonia technology, and in particular to a liquid ammonia cold energy recovery and utilization device. Background Technology
[0002] In existing high-pressure hydrogen and nitrogen ammonia synthesis processes, the cooling and separation section is a crucial step. Hydrogen and nitrogen are combined into ammonia under high temperature and pressure within the synthesis tower. The tower outlet contains a synthesis gas of hydrogen, nitrogen, and ammonia. After heat recovery and water cooling, the synthesis gas enters an ammonia cooler for further cooling, lowering the temperature to -10℃ to 0℃ before entering the ammonia separator for separation. Low-temperature conditions are more conducive to ammonia separation. The separated liquid ammonia enters a primary flash tank and a secondary flash tank for flash evaporation. Impurities are removed through flash evaporation before the liquid ammonia is sent out.
[0003] The temperature of the synthesis gas entering the ammonia cooler is generally around 25℃. If the temperature needs to be lowered to -10℃ to 0℃, liquid ammonia is generally used as the cold source. The temperature of liquid ammonia in the normal liquid ammonia storage tank is about 30℃, and it can reach 40℃ in hot summer weather. The high temperature of the liquid ammonia cold source results in a large amount of ammonia being added to the ammonia cooler, causing a heavy load on the ammonia refrigeration unit. At the same time, the temperature of liquid ammonia at the outlet of the primary flash tank is generally below zero degrees. If it is directly sent to the secondary flash tank for flashing and then sent out, it will result in a waste of liquid ammonia cooling capacity. Utility Model Content
[0004] The purpose of this invention is to provide a liquid ammonia cold energy recovery and utilization device to solve the problems mentioned in the background art. The device exchanges heat between the low-temperature liquid ammonia at the outlet of the primary flash tank and the high-temperature liquid ammonia from the liquid ammonia storage tank, which is used as a cold source. After the temperature of the liquid ammonia from the liquid ammonia storage tank is reduced, it goes to the ammonia cooler to absorb heat from the synthesis gas and reduce the temperature of the synthesis gas. After the temperature of the low-temperature liquid ammonia at the outlet of the primary flash tank is increased, it is sent to the secondary flash tank for further flashing.
[0005] To achieve the above objectives, the present invention provides a liquid ammonia cold energy recovery and utilization device, comprising a cold source side system, a heat source side system, a heat exchange system, and an automatic control system. The cold source side system includes a primary flash tank, a secondary flash tank, and cold source pipelines. The heat source side system includes an ammonia cooler, an ammonia ice machine, and heat source pipelines. The cold source in the cold source side system and the heat source in the heat source side system exchange heat within the heat exchange system, which is an ammonia heater, including a shell side and a tube side.
[0006] Preferably, the cold source piping sequentially includes a primary flash tank inlet pipe, a primary flash tank outlet pipe, a secondary flash tank inlet pipe, and a secondary flash tank outlet pipe. The primary flash tank inlet pipe is connected to the inlet end of the primary flash tank, the outlet end of the primary flash tank is connected to one end of the primary flash tank outlet pipe, the other end of the primary flash tank outlet pipe is connected to the inlet end of the tube side, the outlet end of the tube side is connected to one end of the secondary flash tank inlet pipe, the other end of the secondary flash tank inlet pipe is connected to the inlet end of the secondary flash tank, and the outlet end of the secondary flash tank is connected to the secondary flash tank outlet pipe.
[0007] Preferably, the heat source pipeline includes, in sequence, a high-temperature liquid ammonia inlet pipe for an ammonia heater, a liquid ammonia inlet pipe for an ammonia cooler, and a gaseous ammonia outlet pipe for an ammonia cooler. The high-temperature liquid ammonia inlet pipe for the ammonia heater is connected to the inlet end of the shell side, the outlet end of the shell side is connected to one end of the liquid ammonia inlet pipe for the ammonia cooler, the other end of the liquid ammonia inlet pipe for the ammonia cooler is connected to the inlet end of the ammonia cooler, the outlet end of the ammonia cooler is connected to one end of the gaseous ammonia outlet pipe for the ammonia cooler, and the other end of the gaseous ammonia outlet pipe for the ammonia cooler is connected to an ammonia refrigeration machine.
[0008] Preferably, the cold source in the cold source side system is low-temperature liquid ammonia separated by an ammonia separator, and the heat source in the heat source side system is high-temperature liquid ammonia compressed by the ammonia ice machine.
[0009] Preferably, an exhaust pipe is provided at the upper end of the primary flash evaporator.
[0010] Preferably, a level gauge I is installed on the primary flash tank, and an automatic regulating valve is installed on the outlet pipe of the primary flash tank.
[0011] Preferably, a level gauge II is installed on the secondary flash tank, and an automatic regulating valve II is installed on the outlet pipe of the secondary flash tank.
[0012] Preferably, a level gauge III is installed on the ammonia cooler, and an automatic regulating valve III is installed on the liquid ammonia inlet pipe of the ammonia cooler.
[0013] Preferably, pressure gauge I and thermometer III are installed on the outlet pipe of the primary flash tank, and thermometer IV and pressure gauge II are installed on the liquid ammonia inlet pipe of the ammonia cooler.
[0014] Preferably, a thermometer I is installed on the outlet pipe of the secondary flash tank, and a thermometer II is installed on the inlet pipe of the high-temperature liquid ammonia of the ammonia heater.
[0015] Therefore, the present invention employs the above-mentioned liquid ammonia cooling capacity recovery and utilization device, which has the following beneficial effects:
[0016] (1) Recover the cold energy of the low-temperature liquid ammonia at the outlet of the first-stage flash tank to save energy and avoid the waste of liquid ammonia cold energy.
[0017] (2) Reduce the load on the ammonia ice machine to ensure long-term stable operation of the equipment.
[0018] (3) This device requires little investment, is highly adjustable, and has great practical value.
[0019] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the process flow of an embodiment of a liquid ammonia cooling capacity recovery and utilization device according to the present invention;
[0021] Reference numerals in the attached diagram: 1. Primary flash tank; 2. Ammonia heater; 3. Secondary flash tank; 4. Ammonia cooler; 5. Primary flash tank inlet pipe; 6. Primary flash tank exhaust pipe; 7. Primary flash tank outlet pipe; 8. Secondary flash tank inlet pipe; 9. Secondary flash tank outlet pipe; 10. High-temperature liquid ammonia inlet pipe for ammonia heater; 11. Liquid ammonia inlet pipe for ammonia cooler; 12. Gaseous ammonia outlet pipe for ammonia cooler; 13. Automatic regulating valve I; 14. Automatic regulating valve II; 15. Automatic regulating valve III; 16. Level gauge I; 17. Level gauge II; 18. Level gauge III; 19. Thermometer I; 20. Thermometer II; 21. Thermometer III; 22. Thermometer IV; 23. Pressure gauge I; 24. Pressure gauge II; 25. Ammonia refrigeration unit. Detailed Implementation
[0022] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.
[0023] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0024] Example
[0025] Please see Figure 1This utility model provides a liquid ammonia cold energy recovery and utilization device, including a cold source side system, a heat source side system, a heat exchange system, and an automatic control system. The cold source side system includes a primary flash tank 1, a secondary flash tank 3, and a cold source pipeline. The heat source side system includes an ammonia cooler 4, an ammonia ice machine 25, and a heat source pipeline. The cold source in the cold source side system and the heat source in the heat source side system exchange heat in the heat exchange system, which is an ammonia heater 2, including a shell side and a tube side.
[0026] The inlet of the primary flash tank 1 is connected to the inlet pipe 5 of the primary flash tank, and the outlet is connected to the outlet pipe 7 and the exhaust pipe 6 of the primary flash tank. In the ammonia synthesis unit, hydrogen and nitrogen are combined into ammonia under high temperature and pressure in the synthesis tower. The outlet of the synthesis tower is a synthesis gas of hydrogen, nitrogen, and ammonia. After heat recovery, the temperature of the synthesis gas drops to -5.7℃ and enters the ammonia separator for separation. The separated liquid ammonia, at -5.7℃, enters the primary flash tank 1 through the inlet pipe 5 of the primary flash tank for flash evaporation, where impurities and unreacted hydrogen and nitrogen are flashed away. After primary flash evaporation, the liquid ammonia is at -5.9℃ and enters the tube side of the ammonia heater 2 through the outlet pipe 7 of the primary flash tank. The flashed gas is sent to the ammonia flare system through the exhaust pipe 6 of the primary flash tank.
[0027] The inlet of ammonia heater 2 is connected to the outlet pipe 7 of the primary flash tank and the high-temperature liquid ammonia inlet pipe 10 of the ammonia heater. Its outlet is connected to the inlet pipe 8 of the secondary flash tank and the liquid ammonia inlet pipe 11 of the ammonia cooler. Liquid ammonia from the liquid ammonia storage tank, at a temperature of 40°C, enters the shell side of ammonia heater 2 through the high-temperature liquid ammonia inlet pipe 10. Low-temperature liquid ammonia from the primary flash tank, at a temperature of -5.9°C, enters the tube side of ammonia heater 2 through the outlet pipe 7 of the primary flash tank. Heat exchange occurs between the two streams of liquid ammonia within ammonia heater 2. The high-temperature liquid ammonia, at 40°C, decreases in temperature to 2.1°C and then enters ammonia cooler 4 through the liquid ammonia inlet pipe 11, serving as the cold source medium for ammonia cooler 4. The low-temperature liquid ammonia, at -5.9°C, increases in temperature to 20°C after heat exchange and enters the secondary flash tank 3 through the inlet pipe 8 of the secondary flash tank for further flashing.
[0028] The inlet of the secondary flash tank 3 is connected to the inlet pipe 8 of the secondary flash tank, and the outlet is connected to the outlet pipe 9 of the secondary flash tank. Liquid ammonia at a temperature of 20°C, which has been cooled by the ammonia heater, enters the secondary flash tank 3 through the inlet pipe 8 for secondary flash evaporation, further removing impurities and purifying the liquid ammonia. The high-quality liquid ammonia is then sent to an external location for sale or used as a raw material for urea production through the outlet pipe 9 of the secondary flash tank.
[0029] The inlet of ammonia cooler 4 is connected to the liquid ammonia inlet pipe 11, and the outlet is connected to the gaseous ammonia outlet pipe 12. Low-temperature liquid ammonia at 2.1℃ enters ammonia cooler 4 through the liquid ammonia inlet pipe 11, serving as the cooling medium. After absorbing heat from the heat source medium of ammonia cooler 4, it becomes gaseous ammonia and is sent to the ammonia refrigeration unit 25 through the gaseous ammonia outlet pipe 12. Through the ammonia refrigeration unit, the gaseous ammonia is compressed back into liquid ammonia for recycling.
[0030] A level gauge I16 is installed on the primary flash tank 1, and an automatic regulating valve I13 is installed on the outlet pipe 7 of the primary flash tank. Level gauge I16 is equipped with DCS remote transmission and high / low limit alarm functions, allowing remote monitoring of the liquid level changes in the primary flash tank via the DCS system. Simultaneously, level gauge I16 and automatic regulating valve I13 form an automatic adjustment loop. Within the DCS system, automatic regulating valve I13 can automatically adjust based on the set value of level gauge I16, stabilizing the liquid level in the primary flash tank at approximately the set value.
[0031] A level gauge II17 is installed on the secondary flash tank 3, and an automatic regulating valve II14 is installed on the outlet pipe 9 of the secondary flash tank. Level gauge II17 is equipped with DCS remote transmission and high / low limit alarm functions, allowing remote monitoring of the liquid level changes in the secondary flash tank via the DCS system. Level gauge II17 and automatic regulating valve II14 form an automatic regulation loop. In the DCS system, automatic regulating valve II14 can automatically adjust according to the set value of level gauge II17, stabilizing the liquid level in the secondary flash tank at approximately the set value.
[0032] A level gauge III18 is installed on the ammonia cooler 4, and an automatic regulating valve III15 is installed on the liquid ammonia inlet pipe 11 of the ammonia cooler. Level gauge III18 is equipped with DCS remote transmission and high / low limit alarm functions, allowing remote monitoring of the ammonia cooler's liquid level changes within the DCS system. Level gauge III18 and automatic regulating valve III15 form an automatic regulation loop. Within the DCS system, automatic regulating valve III15 can automatically adjust according to the set value of level gauge III18, stabilizing the ammonia cooler's liquid level around the set value.
[0033] Pressure gauge I23 and thermometer III21 are installed on the outlet pipe 7 of the primary flash evaporator, and thermometer IV22 and pressure gauge II24 are installed on the liquid ammonia inlet pipe 11 of the ammonia cooler. The pressure gauges and thermometers are equipped with remote transmission capabilities, allowing for remote monitoring of pressure and temperature changes via the DCS system. The system can be adjusted promptly based on these changes to ensure stable operation of the unit.
[0034] A thermometer I19 is installed on the outlet pipe 9 of the secondary flash evaporator, and a thermometer II20 is installed on the inlet pipe 10 of the high-temperature liquid ammonia heater. The thermometers are also equipped with remote transmission capabilities, allowing for remote monitoring of temperature changes via the DCS system. The system can be adjusted promptly based on these temperature fluctuations to ensure stable operation of the unit.
[0035] Therefore, this utility model adopts the above-mentioned liquid ammonia cold energy recovery and utilization device to recover the cold energy of low-temperature liquid ammonia at the outlet of the primary flash tank, save energy, avoid waste of liquid ammonia cold energy, reduce the load of the ammonia ice machine, and ensure long-term stable operation of the equipment. This device has low investment, strong adjustability, and good application value.
[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.
Claims
1. A liquid ammonia cold energy recovery device, characterized in that: The system includes a cold source side system, a heat source side system, a heat exchange system, and an automatic control system. The cold source side system includes a primary flash tank, a secondary flash tank, and cold source piping. The heat source side system includes an ammonia cooler, an ammonia ice machine, and heat source piping. The cold source in the cold source side system and the heat source in the heat source side system exchange heat in the heat exchange system, which is an ammonia heater, including a shell side and a tube side.
2. The liquid ammonia cold recovery device according to claim 1, characterized in that: The cold source piping includes, in sequence, a primary flash tank inlet pipe, a primary flash tank outlet pipe, a secondary flash tank inlet pipe, and a secondary flash tank outlet pipe. The primary flash tank inlet pipe is connected to the inlet end of the primary flash tank, the outlet end of the primary flash tank is connected to one end of the primary flash tank outlet pipe, the other end of the primary flash tank outlet pipe is connected to the inlet end of the tube side, the outlet end of the tube side is connected to one end of the secondary flash tank inlet pipe, the other end of the secondary flash tank inlet pipe is connected to the inlet end of the secondary flash tank, and the outlet end of the secondary flash tank is connected to the secondary flash tank outlet pipe.
3. The liquid ammonia cold recovery device according to claim 2, characterized in that: The heat source pipeline sequentially includes a high-temperature liquid ammonia inlet pipe for an ammonia heater, a liquid ammonia inlet pipe for an ammonia cooler, and a gaseous ammonia outlet pipe for an ammonia cooler. The high-temperature liquid ammonia inlet pipe for the ammonia heater is connected to the inlet end of the shell side, the outlet end of the shell side is connected to one end of the liquid ammonia inlet pipe for the ammonia cooler, the other end of the liquid ammonia inlet pipe for the ammonia cooler is connected to the inlet end of the ammonia cooler, the outlet end of the ammonia cooler is connected to one end of the gaseous ammonia outlet pipe for the ammonia cooler, and the other end of the gaseous ammonia outlet pipe for the ammonia cooler is connected to an ammonia refrigeration machine.
4. The liquid ammonia cold recovery device according to claim 3, characterized in that: The cold source in the cold source side system is low-temperature liquid ammonia separated by the ammonia separator, and the heat source in the heat source side system is high-temperature liquid ammonia compressed by the ammonia ice machine.
5. The liquid ammonia cold recovery device according to claim 4, characterized in that: An exhaust pipe is provided at the upper end of the primary flash evaporator.
6. The liquid ammonia cold recovery device according to claim 5, characterized in that: A level gauge I is installed on the primary flash tank, and an automatic regulating valve is installed on the outlet pipe of the primary flash tank.
7. The liquid ammonia cold recovery device according to claim 6, characterized in that: A level gauge II is installed on the secondary flash tank, and an automatic regulating valve II is installed on the outlet pipe of the secondary flash tank.
8. The liquid ammonia cooling capacity recovery and utilization device according to claim 7, characterized in that: A level gauge III is installed on the ammonia cooler, and an automatic regulating valve III is installed on the liquid ammonia inlet pipe of the ammonia cooler.
9. The liquid ammonia cooling capacity recovery and utilization device according to claim 8, characterized in that: Pressure gauge I and thermometer III are installed on the outlet pipe of the primary flash tank, and thermometer IV and pressure gauge II are installed on the liquid ammonia inlet pipe of the ammonia cooler.
10. A liquid ammonia cooling capacity recovery and utilization device according to claim 9, characterized in that: Thermometer I is installed on the outlet pipe of the secondary flash tank, and thermometer II is installed on the inlet pipe of the high-temperature liquid ammonia of the ammonia heater.