Freeze-drying, refrigerating and heating process system for continuous production by using LNG (liquefied natural gas) cold energy

Abstract

The utility model discloses a freeze-drying, refrigerating and heating process system using LNG (Liquefied Natural Gas) cold energy for continuous production. The system comprises an LNG gasification system, an LNG cold energy transfer system, a pre-freezing defrosting system and a trapping heating system, the LNG gasification system and the cold energy transfer adopt refrigerant heat exchange to transfer cold energy to CO2; the pre-freezing defrosting system converts solid water into liquid water during defrosting through a heat exchanger, releases cold energy and LNG cold energy and transmits the cold energy and the LNG cold energy to a refrigerant CO2, cold is supplied to a pre-freezing bin, and after the CO2 is heated, heat is supplied to a cold trap for defrosting; the trapping heating system transmits cold energy released when materials are heated and LNG cold energy to CO2 through a heat exchanger, cold is supplied to a cold trap, and heat is supplied to a heating bin after CO2 is heated. And by arranging the double cold traps, when one cold trap defrosts, the other cold trap ensures trapping. According to the system, cold and heat in a process system are comprehensively utilized through coupling of various devices, the comprehensive utilization rate of cold energy and hot energy is high, production continuity is achieved through the double cold traps, and the production period is short.

Description

Technical Field

[0001] The utility model belongs to the technical field of freeze-drying, and particularly relates to a freeze-drying refrigeration and heating process system for continuous production using LNG cold energy. Background Technique

[0002] Existing public literature shows that the main energy consumption in the freeze-drying process includes material freezing, heating and drying, defrosting, cold trap trapping, and maintaining vacuum, accounting for 4%, 45%, 25%, and 26% of the total energy consumption respectively. Taking garlic cubes as an example, in one operating cycle of freeze-drying, the refrigerating machine needs to provide about 2.70x10 7 kJ of cooling capacity, including that required for freezing and that required for the cold trap to condense water vapor. The required power consumption is 5632 kWh, which indicates that the freeze-drying refrigeration and heating system has high energy consumption and high cost. Moreover, the freeze-drying process is interrupted because the cold trap cannot trap water vapor during defrosting, resulting in the inability to continuously produce.

[0003] It can be seen that reducing the energy consumption in the freeze-drying process to save costs and shorten the production cycle is an important direction for the development of freeze-drying technology. The patent "A Freeze-Drying Process System and Method Using LNG Cold Energy Based on CO2 Refrigerant" with the patent number CN 117804094A uses the clean energy LNG cold energy to supply cold to the freeze-drying refrigeration system, which can reduce the energy consumption of the freeze-drying refrigeration system, but does not consider the freeze-drying heating system, and cannot achieve a system that both supplies cold and heat, nor can it achieve continuous production. The patent "A Double-Cold-Trap Vacuum Freeze-Dryer" with the patent number CN 219120895U completes continuous production by setting two cold traps connected to the drying chamber respectively, but does not consider the load and time matching between the cold trap and the drying chamber. Content of the Utility Model

[0004] The utility model discloses a freeze-drying refrigeration and heating process system for continuous production using LNG cold energy, aiming to design an LNG cold energy freeze-drying process system with matching cold and heat energy, high comprehensive energy utilization rate, less refrigerant consumption, meeting continuous production, and high process coupling. In the utility model, the flow direction and flow rate of 6 three-way valves can be adjusted, and the operating temperature of CO2 in the energy supply equipment can be controlled to adjust the LNG cold energy obtained by CO2 from the LNG gasification system and the LNG cold energy transfer system and the proportion of CO2 recycled cold to achieve load matching and time matching among the pre-freezing bin, the heating bin, and the double-cold-trap heat exchanger. Through the pressure-reducing valves and compressors in the pre-cooling defrosting circulation system and the trapping heating circulation system, comprehensive utilization of heat and cold can be realized, and the refrigerant consumption can be reduced to lower the cost. The heating temperature is controlled by the cooler in the trapping heating circulation system to ensure excellent quality of freeze-dried products. By setting a double-cold-trap heat exchanger, one of them can ensure trapping while the other is defrosting to ensure production continuity.

[0005] The purpose of the utility model is achieved by at least one of the following technical solutions.

[0006] An LNG cold energy - based freeze - drying refrigeration and heating process system for continuous production, comprising an LNG gasification system, an LNG cold energy transfer system, a pre - freezing and defrosting system, and a trapping and heating system;

[0007] The LNG gasification system includes an LNG storage tank, an LNG pump, an air - cooled vaporizer, a first heat exchanger, and a reheater; the output end of the LNG storage tank is connected in series with the input end of the LNG pump, the input end of the first heat exchanger is communicated with the output end of the LNG pump, the output end of the first heat exchanger is connected in series with the input end of the reheater, and after being connected in series, it is connected in parallel with the air - cooled vaporizer; the output ends of the reheater and the air - cooled vaporizer are both connected to downstream users;

[0008] The LNG coming out of the LNG storage tank enters the first heat exchanger to exchange heat with the primary refrigerant, after gasification and temperature rise, it is further heated through the reheater and then transported to downstream users. When the pre - freezing and defrosting system or the trapping and heating system fails, the LNG is gasified into natural gas in the air - cooled vaporizer and then transported to downstream users;

[0009] The LNG cold energy transfer system is used to transfer cold energy to the pre - freezing and defrosting system and the trapping and heating system. The LNG cold energy transfer system includes a first heat exchanger, a primary liquid refrigerant storage tank, a primary refrigerant pump, a second heat exchanger, and a primary gaseous refrigerant storage tank; the output end of the first heat exchanger is connected to the input end of the primary liquid refrigerant storage tank, the primary liquid refrigerant storage tank is connected in series with the primary refrigerant pump, the output end of the primary refrigerant pump is connected to the cold stream input end of the second heat exchanger, the cold stream output end of the second heat exchanger is connected to the input end of the primary gaseous refrigerant storage tank, and the output end of the primary gaseous refrigerant storage tank is communicated with the hot stream input end of the first heat exchanger;

[0010] The primary refrigerant obtaining the LNG cold energy exchanges heat with CO2 in the second heat exchanger and transfers the cold energy to CO2;

[0011] The pre - freezing and defrosting system includes a pre - freezing and defrosting three - way valve, a pre - freezing chamber, a first compressor, a second three - way valve, a double - cold - trap heat exchanger, and a liquid collection tank;

[0012] The trapping and heating system includes a first three - way valve, a trapping and heating three - way valve, a liquid collection tank, a double - cold - trap heat exchanger, a second compressor, a cooler, a heating chamber, and a drain bucket;

[0013] The pre - freezing and defrosting three - way valve is respectively connected to the hot stream output end of the second heat exchanger, the output end of the liquid collection tank in the pre - freezing and defrosting cycle, and the input end of the first three - way valve; the pre - freezing chamber, the first compressor, the second three - way valve, the double - cold - trap heat exchanger, and the liquid collection tank are connected in series;

[0014] A pre-freezing defrosting pressure reducing valve is provided between the CO2 refrigerant output end of the first three-way valve and the CO2 refrigerant input end of the pre-freezing chamber; the pre-freezing defrosting pressure reducing valve cools the pre-freezing chamber with a set temperature requirement by reducing the pressure of CO2 to lower the temperature, and through the cooperation between the pre-cooling defrosting pressure reducing valve and the first compressor, CO2 circulates, which can greatly reduce the refrigerant consumption to reduce costs;

[0015] The working process of the pre-freezing defrosting system is as follows: In the pre-freezing defrosting cycle, CO2 obtains the cooling capacity released when solid water turns into liquid water and the LNG cooling capacity during defrosting through the second heat exchanger and the dual cold trap heat exchanger, and then enters the pre-freezing chamber to cool the material after reducing the pressure and temperature through the pre-freezing defrosting pressure reducing valve, freezing the moisture in the material into ice, and then entering the first compressor to increase the temperature and pressure and enter the dual cold trap heat exchanger to supply heat and achieve a cycle;

[0016] The first three-way valve is respectively connected to the output end of the pre-freezing defrosting three-way valve, the output end of the heating chamber, and the input end of the liquid collection tank in the trapping heating cycle; the trapping heating three-way valve, the liquid collection tank, the dual cold trap heat exchanger, the second compressor, the cooler, and the heating chamber are connected in series, and the refrigerant output end of the heating chamber communicates with the input end of the trapping heating three-way valve in the trapping heating cycle;

[0017] A trapping heating pressure reducing valve is provided between the output end of the liquid collection barrel and the input end of the dual cold trap heat exchanger; the trapping heating pressure reducing valve cools the dual cold trap heat exchanger with a set temperature requirement by reducing the pressure of CO2 to lower the temperature, and through the cooperation between the trapping heating pressure reducing valve and the first compressor, CO2 circulates, which can greatly reduce the refrigerant consumption to reduce costs;

[0018] The working process of the trapping heating system is as follows: In the trapping heating cycle, CO2 obtains the cooling capacity released during material heating and the LNG cooling capacity through the second heat exchanger and the heating chamber, enters the liquid collection tank to converge, and then enters the dual cold trap heat exchanger to trap the water vapor sublimated from the heating chamber after reducing the pressure and temperature through the trapping heating pressure reducing valve, freezing the water vapor into frost, and then entering the second compressor to increase the temperature and pressure and enter the cooler, and then enter the heating chamber to supply heat and achieve a cycle.

[0019] Furthermore, the LNG gasification system further includes a pressure regulator and a flow meter. The output ends of the air temperature vaporizer and the reheater are both connected in series with the pressure regulator and the flow meter, and the output end of the flow meter is connected to downstream users. The pressure regulator is used to adjust the pressure of the natural gas delivered to downstream users, and the flow meter is used to measure the flow of the natural gas delivered to downstream users.

[0020] Furthermore, a fourth regulating valve is provided between the LNG pump and the first heat exchanger, and a third regulating valve is provided at the output end of the reheater and the output end of the air temperature vaporizer to adjust the flow rate of LNG;

[0021] A first regulating valve is provided between the air-cooled vaporizer and the LNG pump to achieve seamless switching of working conditions.

[0022] Further, an eighth regulating valve for controlling the flow is provided between the output end of the primary refrigerant gas storage tank and the heat stream input end of the first heat exchanger;

[0023] A fifth regulating valve is provided between the output end of the first heat exchanger and the input end of the primary refrigerant liquid storage tank to regulate the flow rate of CO2.

[0024] Further, a sixth regulating valve and a seventh regulating valve are respectively provided at the cold stream input end and the output end of the second heat exchanger, a first stop valve is provided between the first heat exchanger and the reheater, a second stop valve is provided between the pre-freezing bin and the first compressor, a third stop valve is provided between the cooler and the heating bin, a fourth stop valve is provided between the fourth three-way valve and the second heat exchanger, and a fifth stop valve is provided between the double cold trap heat exchanger and the drain bucket, all for controlling the on-off of the branch circuits.

[0025] Further, a material conveying device is provided at the material inlet and outlet of the pre-freezing bin and the heating bin; the material conveying device is used to convey the raw material to the pre-freezing bin for pre-freezing, and after pre-freezing is completed, it is conveyed to the heating bin for heating, and the sublimated and heated material product is conveyed out from the heating bin;

[0026] A drain bucket is provided at the outlet of the double cold trap heat exchanger; the drain bucket is used to collect and drain the water formed by the frost in the double cold trap heat exchanger during the pre-freezing defrosting cycle.

[0027] Further, the circulating medium in the second heat exchanger, the pre-freezing bin, the heating bin, and the double cold trap heat exchanger is the same refrigerant CO2.

[0028] Further, in the pre-freezing defrosting system, a fourth three-way valve is provided between the output end of the second three-way valve and the heat stream input end of the second heat exchanger;

[0029] In the capture heating system, a third three-way valve is provided at the output end of the second compressor and the input end of the cooler, and the output end of the third three-way valve communicates with the input end of the fourth three-way valve;

[0030] By controlling the valve opening and closing and the operating temperature of CO2 in the pre-freezing bin, the heating bin, and the double cold trap heat exchanger, the LNG cold energy obtained by CO2 from the LNG gasification system and the LNG cold energy transfer system and the cold ratio for CO2 circulation are adjusted to achieve load matching and time matching among the pre-freezing bin, the heating bin, and the double cold trap heat exchanger.

[0031] Further, the second heat exchanger and the heating bin need to have the functional characteristics of an evaporator;

[0032] The pre-freezing chamber needs to have the functional characteristics of a condenser;

[0033] The dual cold trap heat exchanger needs to have the functional characteristics of both a condenser and an evaporator.

[0034] In the pre-freezing defrosting cycle and the trapping heating cycle, through the dual cold trap heat exchanger, when one cold trap is in the pre-freezing defrosting cycle, the other cold trap conducts the trapping heating cycle, and they share a set of LNG cold energy transfer system.

[0035] The working process of the freeze-drying refrigeration and heating process system using LNG cold energy for continuous production includes:

[0036] S1. The LNG coming out of the LNG storage tank enters the first heat exchanger to exchange heat with the primary refrigerant. After gasification and temperature rise, it is further heated by the reheater and then transported to downstream users. When the pre-freezing defrosting system or the trapping heating system fails, the LNG is gasified into natural gas in the air-cooled vaporizer and then transported to downstream users;

[0037] S2. The primary refrigerant that obtains the LNG cold energy exchanges heat with CO2 in the second heat exchanger from the primary liquid refrigerant storage tank, and transfers the cold energy to CO2;

[0038] S3. Execute the pre-freezing defrosting cycle and the trapping heating cycle;

[0039] In the pre-freezing defrosting cycle, CO2 obtains the cold energy released when the solid water turns into liquid water during defrosting and the LNG cold energy through the second heat exchanger and the dual cold trap heat exchanger. Then, after reducing pressure and temperature through the pre-freezing defrosting pressure reducing valve, it enters the pre-freezing chamber to supply cold to the material, freezes the moisture in the material into ice, and then enters the first compressor to increase the temperature and pressure and enter the dual cold trap heat exchanger to supply heat and complete the cycle;

[0040] In the trapping heating cycle, CO2 obtains the cold energy released when the material is heated and the LNG cold energy through the second heat exchanger and the heating chamber. After converging in the liquid collection tank, it enters the dual cold trap heat exchanger to trap the water vapor sublimated from the heating chamber after reducing pressure and temperature through the trapping heating pressure reducing valve, freezes the water vapor into frost, and then enters the second compressor to increase the temperature and pressure and enter the cooler, and then enters the heating chamber to supply heat and complete the cycle.

[0041] This process system can adjust the flow direction and flow rate of 6 three-way valves and control the operating temperature of CO2 in the energy supply equipment to adjust the LNG cold energy obtained by CO2 from the LNG gasification system and the LNG cold energy transfer system and the cold utilization ratio of the CO2 cycle, so as to achieve the load matching and time matching among the pre-freezing chamber, the heating chamber, and the double cold trap heat exchanger. Through the pressure reducing valves and compressors in the pre-cooling defrosting cycle system and the capture heating cycle system, comprehensive utilization of cold and heat can be achieved. CO2 serves as both a cold supply working medium and a heat supply working medium, which can greatly reduce the amount of refrigerant used to reduce costs. The heating temperature is controlled by the cooler in the capture heating cycle system to ensure excellent quality of the freeze-dried products. By setting up a double cold trap heat exchanger, capture is ensured by one while the other is defrosting to ensure production continuity.

[0042] Compared with the prior art, the utility model has the following beneficial effects:

[0043] 1. The utility model uses multiple three-way valves to adjust the LNG cold energy obtained by CO2 from the LNG gasification system and the LNG cold energy transfer system and the cold utilization ratio of the CO2 cycle, so as to achieve the load matching and time matching among the pre-freezing chamber, the heating chamber, and the double cold trap heat exchanger.

[0044] 2. Through the coupling among multiple equipment such as pressure reducing valves, compressors, and heat exchangers, the utility model comprehensively utilizes the cold and heat in the freeze-drying process system, which can greatly improve the energy utilization rate and greatly reduce the amount of refrigerant used to reduce costs.

[0045] 3. The utility model uses a double cold trap heat exchanger to ensure capture by one while the other is defrosting to ensure production continuity, which can shorten the freeze-drying cycle.

[0046] 4. By controlling the parameters of equipment such as pressure reducing valves, compressors, heat exchangers, and coolers, the utility model can control the refrigeration or heating temperature to ensure excellent quality of the freeze-dried products. Description of the Drawings

[0047] Figure 1 Schematic diagram of the freeze-drying refrigeration and heating process system for continuous production using LNG cold energy according to the embodiment of the utility model;

[0048] Figure 2 Schematic diagram of the process system during pre-cooling defrosting according to the embodiment of the utility model;

[0049] Figure 3 Schematic diagram of the process system during capture heating according to the embodiment of the utility model. Detailed Embodiments

[0050] To better understand the utility model, the following further illustrates the utility model with reference to the drawings and embodiments. However, the scope required to be protected by the utility model is not limited to the scope described in the embodiments.

[0051] Example 1:

[0052] In this embodiment, the LNG cold energy is used in a freeze-drying refrigeration and heating process system for continuous production, such as Figure 1 shown, which includes an LNG gasification system, an LNG cold energy transfer system, a pre-freezing and defrosting system, and a trapping and heating system.

[0053] The LNG gasification system includes an LNG storage tank 1, an LNG pump 2, an air-cooled vaporizer 4, a first heat exchanger 12, and a reheater 11; the output end of the LNG storage tank 1 is connected in series with the input end of the LNG pump 2, the input end of the first heat exchanger 12 is communicated with the output end of the LNG pump 2, the output end of the first heat exchanger 12 is connected in series with the input end of the reheater 11, and after being connected in series, it is connected in parallel with the air-cooled vaporizer 4; the LNG coming out of the LNG storage tank 1 enters the first heat exchanger 12 to exchange heat with the primary refrigerant, and after gasification and temperature rise, it enters the downstream users after further heating by the reheater 11;

[0054] The LNG cold energy transfer system is used to transfer cold energy to the receiving end. The cold energy transfer system includes a first heat exchanger 12, a primary liquid refrigerant storage tank 14, a primary refrigerant pump 15, a second heat exchanger 17, and a primary refrigerant gas storage tank 19. The output end of the first heat exchanger 12 is connected to the input end of the primary liquid refrigerant storage tank 14, the primary liquid refrigerant storage tank 14 is connected in series with the primary refrigerant pump, and the output end of the primary gas refrigerant storage tank 19 communicates with the first heat exchanger 12.

[0055] The primary refrigerant obtaining the LNG cold energy exchanges heat with CO2 in the second heat exchanger 17 and transfers the cold energy to CO2.

[0056] In this embodiment, a fourth regulating valve 9 is provided between the LNG pump 2 and the first heat exchanger 12, and a third regulating valve 6 is provided at the output end of the reheater 11 and the output end of the air-cooled vaporizer 4 to regulate the flow rate of LNG; a first regulating valve 3 is provided between the air-cooled vaporizer 4 and the LNG pump 2 to achieve seamless switching of working conditions. An eighth regulating valve 20 for controlling the flow passage is provided between the output end of the primary refrigerant gas storage tank 19 and the input end of the hot stream of the first heat exchanger 12, and a sixth regulating valve 16 and a seventh regulating valve 18 for controlling the on / off of the branch are respectively provided at the input end and the output end of the cold stream of the second heat exchanger 17.

[0057] The pre-freezing and defrosting system includes a pre-freezing and defrosting three-way valve 21, a pre-freezing chamber 24, a first compressor 26, a second three-way valve 27, a double cold trap heat exchanger 28, and a liquid collection tank 29;

[0058] The capture and heating system includes a first three-way valve 22, a capture and heating three-way valve 31, a liquid collection tank 29, a dual cold trap heat exchanger 28, a second compressor 33, a cooler 35, a heating chamber 37, and a drain bucket 41;

[0059] The pre-freezing and defrosting three-way valve 21 is respectively connected to the heat flow output end of the second heat exchanger 17, the output end of the liquid collection tank 29 in the pre-freezing and defrosting cycle, and the input end of the first three-way valve 22; the pre-freezing chamber 24, the first compressor 26, the second three-way valve 27, the dual cold trap heat exchanger 28, and the liquid collection tank 29 are connected in series;

[0060] A pre-freezing and defrosting pressure reducing valve 23 is provided between the CO2 refrigerant output end of the first three-way valve 22 and the CO2 refrigerant input end of the pre-freezing chamber 24; the pre-freezing and defrosting pressure reducing valve 23 supplies cold to the pre-freezing chamber 24 with a set temperature requirement by reducing the pressure of CO2 to lower the temperature, and through the cooperation between the pre-cooling and defrosting pressure reducing valve 23 and the first compressor 26, the CO2 circulates, which can greatly reduce the refrigerant consumption to reduce costs;

[0061] The working process of the pre-freezing and defrosting system is as follows: in the pre-freezing and defrosting cycle, CO2 obtains the cold released when solid water turns into liquid water during defrosting and the cold of LNG through the second heat exchanger 17 and the dual cold trap heat exchanger 28, and then enters the pre-freezing chamber 24 to supply cold to the material after being depressurized and cooled by the pre-freezing and defrosting pressure reducing valve 23, so that the moisture in the material freezes into ice, and then enters the first compressor 26 to increase the temperature and pressure and enter the dual cold trap heat exchanger 28 to supply heat and achieve circulation;

[0062] The first three-way valve 22 is respectively connected to the output end of the pre-freezing and defrosting three-way valve 21, the output end of the heating chamber 37, and the input end of the liquid collection tank 29 in the capture and heating cycle; the capture and heating three-way valve 31, the liquid collection tank 29, the dual cold trap heat exchanger 28, the second compressor 33, the cooler 35, and the heating chamber 37 are connected in series, and the refrigerant output end of the heating chamber 37 is communicated with the input end of the capture and heating three-way valve 31 in the capture and heating cycle;

[0063] A capture and heating pressure reducing valve 32 is provided between the output end of the liquid collection bucket 29 and the input end of the dual cold trap heat exchanger 28; the capture and heating pressure reducing valve 32 supplies cold to the dual cold trap heat exchanger 28 with a set temperature requirement by reducing the pressure of CO2 to lower the temperature, and through the cooperation between the capture and heating pressure reducing valve 32 and the first compressor 33, the CO2 circulates, which can greatly reduce the refrigerant consumption to reduce costs;

[0064] The working process of the capture heating system is as follows: In the capture heating cycle, CO2 obtains the cold energy released during material heating and the LNG cold energy through the second heat exchanger 17 and the heating chamber 37. After converging in the liquid collection tank 29, it enters the double cold trap heat exchanger 28 after being depressurized and cooled by the capture heating pressure reducing valve 32 to capture the water vapor sublimated from the heating chamber 37, turning the water vapor into frost. Then it enters the second compressor 33 to increase the temperature and pressure, enters the cooler 35, and then enters the heating chamber 37 for heat supply to complete the cycle.

[0065] In this embodiment, in the pre-freezing defrosting cycle and the capture heating cycle, the double cold trap heat exchanger 28 is used to enable one cold trap to perform the capture heating cycle while the other cold trap performs the pre-freezing defrosting cycle, and they share a set of LNG cold energy transfer system.

[0066] In this embodiment, in the pre-freezing defrosting system, a fourth three-way valve 38 is provided between the output end of the second three-way valve 27 and the heat stream input end of the second heat exchanger; in the capture heating system, a third three-way valve 34 is provided between the output end of the second compressor 33 and the input end of the cooler 35. By controlling the valve switch and opening degree, and by controlling the operating temperature of CO2 in the pre-freezing chamber 24, heating chamber 37, and double cold trap heat exchanger 28, the LNG cold energy obtained by CO2 from the LNG gasification system and the LNG cold energy transfer system and the cold ratio for CO2 circulation can be adjusted to achieve load matching and time matching among the pre-freezing chamber 24, heating chamber 37, and double cold trap heat exchanger 28.

[0067] In this embodiment, the heat transfer medium in the second heat exchanger 17, pre-freezing chamber 24, heating chamber 37, and double cold trap heat exchanger 28 is the same refrigerant CO2;

[0068] In this embodiment, the second heat exchanger 17 and the heating chamber 37 have the functional characteristics of an evaporator, the pre-freezing chamber 24 has the functional characteristics of a condenser, and the double cold trap heat exchanger 28 has both the functional characteristics of a condenser and an evaporator, that is, CO2 serves as both a cold supply working medium and a heat supply working medium, which can greatly reduce the refrigerant consumption to reduce costs.

[0069] In this embodiment, the comprehensive utilization of heat and cold can be achieved through the pressure reducing valves and compressors in the pre-cooling defrosting cycle system and the capture heating cycle system. By setting the double cold trap heat exchanger 28, capture can be ensured by the other cold trap when one is defrosting to ensure production continuity, and the heating temperature can be controlled through the cooler 35 in the capture heating cycle system to ensure excellent quality of freeze-dried products.

[0070] Embodiment 2:

[0071] In this embodiment, when performing pre-cooling defrosting, the LNG cold energy is used in the freeze-drying refrigeration heating process system for continuous production, such as Figure 2As shown, it includes an LNG vaporization system, an LNG cold energy transfer system, and a pre-freezing and defrosting system;

[0072] The LNG vaporization system includes an LNG storage tank 1, an LNG pump 2, an air-cooled vaporizer 4, a first heat exchanger 12, and a reheater 11; the output end of the LNG storage tank 1 is connected in series with the input end of the LNG pump 2, the input end of the first heat exchanger 12 is communicated with the output end of the LNG pump 2, the output end of the first heat exchanger 12 is connected in series with the input end of the reheater 11, and after being connected in series, it is connected in parallel with the air-cooled vaporizer 4; the LNG coming out of the LNG storage tank 1 enters the first heat exchanger 12 to exchange heat with the primary refrigerant, after vaporizing and warming up, it enters downstream users after being further heated by the reheater 11;

[0073] The LNG cold energy transfer system is used to transfer cold energy to the receiving end, and the cold energy transfer system includes a first heat exchanger 12, a primary liquid refrigerant storage tank 14, a primary refrigerant pump 15, a second heat exchanger 17, and a primary refrigerant gas storage tank 19. The output end of the first heat exchanger 12 is connected to the input end of the primary liquid refrigerant storage tank 14, the primary liquid refrigerant storage tank 14 is connected in series with the primary refrigerant pump, and the output end of the primary gaseous refrigerant storage tank 19 communicates with the first heat exchanger 12.

[0074] The primary refrigerant obtaining the cold energy of LNG exchanges heat with CO2 in the second heat exchanger 17 and transfers the cold energy to CO2.

[0075] A fourth regulating valve 9 is arranged between the LNG pump 2 and the first heat exchanger 12 to regulate the flow rate of LNG, and a first regulating valve 3 is arranged between the air-cooled vaporizer 4 and the LNG pump 2 to achieve seamless switching of working conditions. An eighth regulating valve 20 for controlling the flow circulation is arranged between the output end of the primary refrigerant gas storage tank 19 and the input end of the hot stream of the first heat exchanger 12, and a sixth regulating valve 16 and a seventh regulating valve 18 for controlling the on-off of the branch are respectively arranged at the input end and the output end of the cold stream of the second heat exchanger 17;

[0076] The pre-freezing and defrosting system includes a pre-freezing and defrosting three-way valve 21, a pre-freezing bin 24, a first compressor 26, a second three-way valve 27, a double cold trap heat exchanger 28, a liquid collection tank 29, and a material conveying device 30; the pre-freezing and defrosting three-way valve 21 is respectively connected to the output end of the hot stream of the second heat exchanger 17, the output end of the liquid collection tank 29 in the pre-freezing and defrosting cycle, and the input end of the first three-way valve 22; the pre-freezing bin 24, the first compressor 26, the second three-way valve 27, the double cold trap heat exchanger 28, and the liquid collection tank 29 are connected in series;

[0077] A pre-freezing and defrosting pressure reducing valve 23 is arranged between the CO2 refrigerant output end of the first three-way valve 22 and the CO2 refrigerant input end of the pre-freezing bin 24;

[0078] In the pre-freezing defrosting cycle, CO2 can obtain the cooling capacity released when solid water turns into liquid water during defrosting and the LNG cooling capacity through the second heat exchanger 17 and the double cold trap heat exchanger 28. Then, after being depressurized and cooled by the pre-freezing defrosting pressure reducing valve 23, it enters the pre-freezing chamber 24 to supply cold to the material, freezing the moisture in the material into ice. Then it enters the first compressor 26 to increase the temperature and pressure and enters the double cold trap heat exchanger 28 to supply heat and achieve a cycle.

[0079] In one embodiment, the LNG coming out of the LNG storage tank 1 enters the first heat exchanger 12 under the conditions of about 30 bar and -162 °C. The LNG first exchanges heat with the primary refrigerant propane at -25 °C and 1.55 bar to increase the temperature to -27 °C, and then enters the reheater 11 to be reheated and increased to above 5 °C and then sent to downstream users through the flow meter 8.

[0080] The primary refrigerant propane in the first heat exchanger 12 is cooled by heat exchange and condensed to -35 °C and then enters the second heat exchanger 17 to exchange heat with gaseous CO2. The CO2 at 16.5 bar and -28 °C coming out of the liquid collection barrel 29 is depressurized and cooled to 14.25 bar and -30 °C by the pre-freezing defrosting pressure reducing valve 23 and enters the pre-freezing chamber 24 to supply cold. After heating up, it enters the first compressor 26 to increase the temperature and pressure to 16.5 bar and -8 °C and then is split. One stream enters the LNG cold energy transfer system to obtain cold and is cooled to -28 °C after exchanging heat with the primary refrigerant propane in the second heat exchanger 17, and the other stream enters the double cold trap heat exchanger 28 to exchange heat with the frost formed by trapping water vapor and obtain cold and is cooled to -28 °C, and converges with the other stream to the liquid collection barrel 29 to achieve a cycle.

[0081] Among them, by controlling the valve opening or closing of the pre-freezing defrosting three-way valve 21 and the second three-way valve 27, and controlling the operating temperature of CO2 in the pre-freezing chamber 24 and the double cold trap heat exchanger 28, the CO2 splitting ratio can be controlled to achieve the load matching between the required cold capacity of the pre-freezing chamber 24 and the required heat of the double cold trap heat exchanger 28.

[0082] The heat exchange medium in the second heat exchanger 17, the pre-freezing chamber 24, and the double cold trap heat exchanger 28 is the same refrigerant CO2. The second heat exchanger 17 and the double cold trap heat exchanger 28 have the functional characteristics of an evaporator, and the pre-freezing chamber 24 has the functional characteristics of a condenser, that is, CO2 serves as both a cold supply working medium and a heat supply working medium, and through the cooperation between the pre-cooling defrosting pressure reducing valve 23 and the first compressor 26, CO2 circulates, which can greatly reduce the refrigerant consumption to reduce costs.

[0083] After Figure 2After the process flow, the results shown in Table 1 are obtained. The data results of 14 embodiments are listed in the table. The results show that the electric energy of 3.72 kWh, the LNG of 230 kg / h, and the CO2 recycling refrigerant of 1572 kg / h can provide 137 kWh of cooling capacity for the pre-freezing warehouse 24 and 94 kWh of heat for the double cold trap heat exchanger 28, and can complete the freeze-drying of 2000 kg of raw materials.

[0084] Table 1

[0085]

[0086] Example 3:

[0087] In this embodiment, when performing capture heating, the cold energy of LNG is used in the freeze-drying refrigeration and heating process system for continuous production, as Figure 3 shown, including an LNG gasification system, an LNG cold energy transfer system, and a capture heating system;

[0088] The LNG gasification system includes an LNG storage tank 1, an LNG pump 2, an air-cooled vaporizer 4, a first heat exchanger 12, and a reheater 11; the output end of the LNG storage tank 1 is connected in series with the input end of the LNG pump 2, the input end of the first heat exchanger 12 is communicated with the output end of the LNG pump 2, the output end of the first heat exchanger 12 is connected in series with the input end of the reheater 11, and after being connected in series, it is connected in parallel with the air-cooled vaporizer 4; the LNG coming out of the LNG storage tank 1 enters the first heat exchanger 12 to exchange heat with the primary refrigerant, and after gasification and temperature rise, it enters the downstream user after further heating through the reheater 11;

[0089] The LNG cold energy transfer system is used to transfer cold energy to the receiving end. The cold energy transfer system includes a first heat exchanger 12, a primary liquid refrigerant storage tank 14, a primary refrigerant pump 15, a second heat exchanger 17, and a primary refrigerant gas storage tank 19. The output end of the first heat exchanger 12 is connected to the input end of the primary liquid refrigerant storage tank 14, the primary liquid refrigerant storage tank 14 is connected in series with the primary refrigerant pump, and the output end of the primary gas refrigerant storage tank 19 communicates with the first heat exchanger 12. The primary refrigerant obtaining the cold energy of LNG exchanges heat with CO2 in the second heat exchanger 17 and transfers the cold energy to CO2.

[0090] A fourth regulating valve 9 is provided between the LNG pump 2 and the first heat exchanger 12 to regulate the flow rate of LNG, and a first regulating valve 3 is provided between the air-cooled vaporizer 4 and the LNG pump 2 to achieve seamless switching of working conditions. An eighth regulating valve 20 for controlling the flow circulation is provided between the output end of the primary refrigerant gas storage tank 19 and the input end of the hot stream of the first heat exchanger 12, and a sixth regulating valve 16 and a seventh regulating valve 18 for controlling the on-off of the branch are respectively provided at the input end and the output end of the cold stream of the second heat exchanger 17.

[0091] The capture and heating system includes a first three-way valve 22, a capture and heating three-way valve 31, a liquid collection tank 29, a double cold trap heat exchanger 28, a second compressor 33, a cooler 35, a heating chamber 37, a material conveying device 30, and a drain bucket 41; the first three-way valve 22 is respectively connected to the output end of the pre-freezing defrosting three-way valve 21, the output end of the heating chamber 37, and the input end of the liquid collection tank 29 in the capture and heating cycle; the capture and heating three-way valve 31, the liquid collection tank 29, the double cold trap heat exchanger 28, the second compressor 33, the cooler 35, and the heating chamber 37 are connected in series, and the refrigerant output end of the heating chamber 37 communicates with the input end of the capture and heating three-way valve 31 in the capture and heating cycle;

[0092] A capture and heating pressure reducing valve 32 is provided between the output end of the liquid collection bucket 29 and the input end of the double cold trap heat exchanger 28;

[0093] In the capture and heating cycle, CO2 can obtain the cold energy released during material heating and LNG cold energy through the second heat exchanger 17 and the heating chamber 37. After converging in the liquid collection tank 29, it enters the double cold trap heat exchanger 28 after being depressurized and cooled by the capture and heating pressure reducing valve 32 to capture the water vapor sublimated from the heating chamber 37, freeze the water vapor into frost, and then enter the second compressor 33 to increase the temperature and pressure and enter the cooler 35, and then enter the heating chamber 37 for heat supply to achieve a cycle.

[0094] In one embodiment, the LNG coming out of the LNG storage tank 1 enters the first heat exchanger 12 under the conditions of about 30 bar and -162 °C. The LNG first exchanges heat with the primary refrigerant propane at -25 °C and 1.55 bar to increase the temperature to -27 °C, and then enters the reheater 11 to be reheated and increased in temperature to above 5 °C and then sent to downstream users through the flow meter 8;

[0095] The primary refrigerant propane in the first heat exchanger 12 exchanges heat and cools down, condenses to -35 °C and then enters the second heat exchanger 17 to exchange heat with gaseous CO2. The CO2 at 14.3 bar and -28 °C coming out of the liquid collection bucket 29 is depressurized and cooled to 6.8 bar and -50 °C by the capture and heating pressure reducing valve 32 and enters the double cold trap heat exchanger 28 for cooling. After the temperature is increased, it enters the second compressor 33 to increase the temperature and pressure to 14.3 bar and 12 °C and then is split. One stream enters the LNG cold energy transfer system to exchange heat with the primary refrigerant propane in the second heat exchanger 17 to obtain cold energy and cool down to -30 °C, and the other stream is cooled to -10 °C by the cooler 35 and then enters the heating chamber 37 to exchange heat with the pre-frozen material to obtain cold energy and cool down to -30 °C, and converges with the other stream to the liquid collection bucket 29 to achieve a cycle.

[0096] Among them, by controlling the valve opening or closing of the trapping heating three-way valve 31 and the third three-way valve 34, and controlling the operating temperatures of CO2 in the heating chamber 37 and the dual cold trap heat exchanger 28, the CO2 diversion ratio can be controlled to achieve the load matching between the cooling capacity required by the heating chamber 37 and the heat quantity required by the dual cold trap heat exchanger 28.

[0097] The heat exchange medium in the second heat exchanger 17, the heating chamber 37, and the dual cold trap heat exchanger 28 is the same refrigerant CO2. The second heat exchanger 17 and the heating chamber 37 have the functional characteristics of an evaporator, and the dual cold trap heat exchanger 28 has the functional characteristics of a condenser. That is, CO2 serves as both a cooling working medium and a heating working medium, and through the cooperation between the trapping heating pressure reducing valve 32 and the first compressor 35, CO2 circulates, which can greatly reduce the refrigerant consumption to reduce costs.

[0098] By controlling the outlet temperature of the cooler 35, the temperature of the refrigerant entering the heating chamber can be controlled to ensure that the freeze-dried product is not damaged and to ensure excellent quality of the freeze-dried product.

[0099] After Figure 3 the process flow, the results shown in Table 2 are obtained. The data results of 14 embodiments are listed in the table. The results show that 21 kWh of electricity, 8.33 kg / h of LNG, and 1740 kg / h of CO2 circulating refrigerant can provide 147 kWh of cooling capacity for the dual cold trap heat exchanger 28 and 156.48 kWh of heat for the heating chamber 37, and can complete the freeze-drying of 2000 kg of raw materials.

[0100] Table 2

[0101]

[0102] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A freeze-drying refrigeration and heating process system using LNG cold energy for continuous production, characterized in that: It includes an LNG vaporization system, an LNG cold energy transfer system, a pre-freezing and defrosting system, and a trapping and heating system; The LNG vaporization system includes an LNG storage tank (1), an LNG pump (2), an air-cooled vaporizer (4), a first heat exchanger (12), and a reheater (11); the output end of the LNG storage tank (1) is connected in series with the input end of the LNG pump (2), the input end of the first heat exchanger (12) is communicated with the output end of the LNG pump (2), the output end of the first heat exchanger (12) is connected in series with the input end of the reheater (11), and after being connected in series, it is connected in parallel with the air-cooled vaporizer (4); the output ends of the reheater (11) and the air-cooled vaporizer (4) are both connected to downstream users; The LNG coming out of the LNG storage tank (1) enters the first heat exchanger (12) to exchange heat with the primary refrigerant, after gasifying and warming up, it is further heated by the reheater (11) and then transported to downstream users. When the pre-freezing and defrosting system or the trapping and heating system fails, the LNG is gasified into natural gas in the air-cooled vaporizer (4) and then transported to downstream users; The LNG cold energy transfer system is used to transfer cold energy to the pre-freezing and defrosting system and the trapping and heating system. The LNG cold energy transfer system includes a first heat exchanger (12), a primary refrigerant liquid storage tank (14), a primary refrigerant pump (15), a second heat exchanger (17), and a primary refrigerant gas storage tank (19); the output end of the first heat exchanger (12) is connected to the input end of the primary refrigerant liquid storage tank (14), the primary refrigerant liquid storage tank (14) is connected in series with the primary refrigerant pump (15), the output end of the primary refrigerant pump (15) is connected to the cold stream input end of the second heat exchanger (17), the cold stream output end of the second heat exchanger (17) is connected to the input end of the primary gaseous refrigerant storage tank (19), and the output end of the primary gaseous refrigerant storage tank (19) is communicated with the hot stream input end of the first heat exchanger (12); The primary refrigerant obtaining the cold energy of LNG exchanges heat with CO2 in the second heat exchanger (17) and transfers the cold energy to CO2; The pre-freezing and defrosting system includes a pre-freezing and defrosting three-way valve (21), a pre-freezing bin (24), a first compressor (26), a second three-way valve (27), a double cold trap heat exchanger (28), and a liquid collection tank (29); The trapping and heating system includes a first three-way valve (22), a trapping and heating three-way valve (31), a liquid collection tank (29), a double cold trap heat exchanger (28), a second compressor (33), a cooler (35), a heating bin (37), and a drainage bucket (41); The pre-freezing and defrosting three-way valve (21) is respectively connected to the hot stream output end of the second heat exchanger (17), the output end of the liquid collection tank (29) in the pre-freezing and defrosting cycle, and the input end of the first three-way valve (22); the pre-freezing bin (24), the first compressor (26), the second three-way valve (27), the double cold trap heat exchanger (28), and the liquid collection tank (29) are connected in series; A pre-freezing and defrosting pressure reducing valve (23) is provided between the CO2 refrigerant output end of the first three-way valve (22) and the CO2 refrigerant input end of the pre-freezing bin (24); During the pre-freezing and defrosting cycle, CO2 obtains the cooling capacity released when solid water turns into liquid water during defrosting and the LNG cooling capacity through the second heat exchanger (17) and the dual cold trap heat exchanger (28), and then enters the pre-freezing chamber (24) through the pre-freezing and defrosting pressure reducing valve (23) to cool the material after pressure reduction and temperature reduction, freezing the moisture in the material into ice, and then entering the first compressor (26) to increase the temperature and pressure and enter the dual cold trap heat exchanger (28) to supply heat and complete the cycle; The first three-way valve (22) is respectively connected to the output end of the pre-freezing and defrosting three-way valve (21), the output end of the heating chamber (37), and the input end of the liquid collection tank (29) in the trapping and heating cycle; the trapping and heating three-way valve (31), the liquid collection tank (29), the dual cold trap heat exchanger (28), the second compressor (33), the cooler (35), and the heating chamber (37) are connected in series, and the refrigerant output end of the heating chamber (37) communicates with the input end of the trapping and heating three-way valve (31) in the trapping and heating cycle; A trapping and heating pressure reducing valve (32) is provided between the output end of the liquid collection tank (29) and the input end of the dual cold trap heat exchanger (28); In the trapping and heating cycle, CO2 obtains the cooling capacity released during material heating and the LNG cooling capacity through the second heat exchanger (17) and the heating chamber (37), enters the liquid collection tank (29) to converge, and then enters the dual cold trap heat exchanger (28) through the trapping and heating pressure reducing valve (32) after pressure reduction and temperature reduction to trap the water vapor sublimated from the heating chamber (37), freeze the water vapor into frost, and then enter the second compressor (33) to increase the temperature and pressure and enter the cooler (35), and then enter the heating chamber (37) to supply heat and complete the cycle.

2. The freeze-drying refrigeration and heating process system using LNG cold energy for continuous production according to claim 1, wherein: The LNG gasification system further includes a pressure regulator (7) and a flow meter (8). The output ends of the air-cooled vaporizer (4) and the reheater (11) are both connected in series with the pressure regulator (7) and the flow meter (8). The output end of the flow meter (8) is connected to downstream users. The pressure regulator (7) is used to adjust the pressure of the natural gas supplied to downstream users, and the flow meter (8) is used to measure the flow rate of the natural gas supplied to downstream users.

3. The freeze-drying refrigeration and heating process system for continuous production using LNG cold energy according to claim 1, characterized in that: A fourth regulating valve (9) is provided between the LNG pump (2) and the first heat exchanger (12). A third regulating valve (6) is provided at the output end of the reheater (11) and the output end of the air-cooled vaporizer (4) to adjust the flow rate of LNG; A first regulating valve (3) is provided between the air-cooled vaporizer (4) and the LNG pump (2) to achieve seamless switching of working conditions.

4. The freeze-drying refrigeration and heating process system using LNG cold energy for continuous production according to claim 1, characterized in that: An eighth regulating valve (20) for controlling the flow circulation is provided between the output end of the primary refrigerant gas storage tank (19) and the hot stream input end of the first heat exchanger (12); A fifth regulating valve (13) is provided between the output end of the first heat exchanger (12) and the input end of the primary refrigerant liquid storage tank (14) to adjust the flow rate of CO2.

5. The freeze-drying refrigeration and heating process system using LNG cold energy for continuous production according to claim 1, characterized in that: A sixth regulating valve (16) and a seventh regulating valve (18) are respectively arranged at the cold fluid inlet end and the output end of the second heat exchanger (17). A first stop valve (10) is arranged between the first heat exchanger (12) and the reheater (11). A second stop valve (25) is arranged between the pre-freezing bin (24) and the first compressor (26). A third stop valve (36) is arranged between the cooler (35) and the heating bin (37). A fourth stop valve (39) is arranged between the fourth three-way valve (38) and the second heat exchanger (17). A fifth stop valve (40) is arranged between the double cold trap heat exchanger (28) and the drain bucket (41), all of which are used to control the on-off of the branch circuits.

6. The freeze-drying refrigeration and heating process system for continuous production using the cold energy of LNG according to claim 1, wherein: A material conveying device (30) is arranged at the material inlet and outlet of the pre-freezing bin (24) and the heating bin (37); the material conveying device (30) is used to convey raw materials to the pre-freezing bin (24) for pre-freezing, and after the pre-freezing is completed, convey them to the heating bin (37) for heating, and convey the material products after sublimation heating out of the heating bin (37).

7. The freeze-drying refrigeration and heating process system using LNG cold energy for continuous production according to claim 1, characterized in that: The drain bucket (41) is arranged at the outlet of the double cold trap heat exchanger (28); the drain bucket (41) is used to collect the water formed by the frost melting in the double cold trap heat exchanger (28) during the pre-freezing defrosting cycle and drain it off.

8. The freeze-drying refrigeration and heating process system using LNG cold energy for continuous production according to claim 1, characterized in that: The circulating medium in the second heat exchanger (17), the pre-freezing bin (24), the heating bin (37), and the double cold trap heat exchanger (28) is the same refrigerant CO2.

9. The freeze-drying refrigeration and heating process system for continuous production using LNG cold energy according to claim 1, characterized in that: In the pre-freezing defrosting system, a fourth three-way valve (38) is arranged between the output end of the second three-way valve (27) and the hot fluid inlet end of the second heat exchanger (17).

10. The freeze-drying refrigeration and heating process system using LNG cold energy for continuous production according to claim 1, characterized in that: In the trapping and heating system, a third three-way valve (34) is arranged on the output end of the second compressor (33) and the input end of the cooler (35), and the output end of the third three-way valve (34) is communicated with the input end of the fourth three-way valve (38); By controlling the opening and closing of the valves and the operating temperature of CO2 in the pre-freezing bin (24), the heating bin (37), and the double cold trap heat exchanger (28), the LNG cold energy obtained by CO2 from the LNG gasification system and the LNG cold energy transfer system and the cold ratio for CO2 circulation are adjusted to achieve load matching and time matching among the pre-freezing bin (24), the heating bin (37), and the double cold trap heat exchanger (28).

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