CN117804094A - Based on CO 2 LNG cold energy of refrigerant used for freeze-drying process system and method - Google Patents
Based on CO 2 LNG cold energy of refrigerant used for freeze-drying process system and method Download PDFInfo
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- 238000004108 freeze drying Methods 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 65
- 230000008569 process Effects 0.000 title claims abstract description 49
- 238000005057 refrigeration Methods 0.000 claims abstract description 70
- 238000002309 gasification Methods 0.000 claims abstract description 33
- 238000004064 recycling Methods 0.000 claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 17
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- 238000011112 process operation Methods 0.000 abstract 1
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Abstract
The invention discloses a method based on CO 2 LNG cold energy of the refrigerant is used for a freeze-drying process system and method. The system comprises an LNG gasification system, a cold energy recycling system and a voltage condensation refrigeration system. The LNG gasification system adopts CO 2 The gasification mode of primary heat exchange of the refrigerant and auxiliary temperature rise of the air temperature type gasifier; the cold energy recycling system utilizes LNG cold energy for pre-freezing the freeze-drying box materials and capturing water vapor by a cold trap; the electric compression refrigeration system is coupled with the LNG cold energy recycling system for supplementing cold so as to improve the process operation flexibility. Aiming at the problems of high energy consumption and multiple types of refrigerants in a freeze dryer refrigerating system, a refrigerant CO is used 2 The heat exchange with LNG is realized to provide cold energy with different amounts and different temperature levels for the freeze-drying refrigeration system, so that one set of process system can meet all types of objectsLyophilizing the material; and the compression system is coupled with the LNG cold energy recycling system to supplement cold energy so as to improve the operation flexibility of the process.
Description
Technical Field
The invention belongs to the technical field of LNG cold energy recycling, and particularly relates to a LNG cold energy recycling system based on CO 2 LNG cold energy of the refrigerant is used for a freeze-drying process system and method.
Background
The existing publications show that the freeze-drying refrigeration system has high energy consumption and high cost, the cold source is not clean, and on the other hand, the recycling rate of the LNG cold energy of the domestic clean cold source is only about 3 percent, and a large amount of LNG cold energy is discharged into the sea or the air in the gasification process, so that serious cold pollution is caused.
Secondly, the prior art for utilizing the LNG cold energy mainly relates to various refrigerants, the difficult problem of refrigerant management is not considered, the prior art for utilizing the LNG cold energy only considers the process design and optimization, the problem of fluctuation of LNG gasification of an actual station is not considered, and the operability of the system on working condition change is poor. The gas consumption of the station is changed along with the change of seasons and time periods by integrating the gas consumption law of the prior LNG station, so that higher requirements on the operation flexibility, sensitivity and the like of the LNG cold energy utilization process can be provided.
The LNG cold energy is used for the situation of construction of the LNG field station, the requirements of peripheral markets, equipment safety, cost benefits, policies and other factors, and has the advantages of less investment, short investment recovery period, high cold energy utilization rate, and good adaptability to the situation of complex working condition background and obvious seasonality. A carbon dioxide refrigeration system utilizing LNG cold energy and a use method (CN 114046610A) utilize single cold source LNG cold energy to exchange heat with multiple refrigerants to realize cold supply, and the problems of fluctuation of LNG gasification and difficult refrigerant management are not considered.
Disclosure of Invention
The invention discloses a method based on CO 2 The LNG cold energy of the refrigerant is used for the freeze-drying process system and method, and the LNG cold energy freeze-drying process system which has the advantages of few refrigerant types, high process coupling, strong working condition adaptability, high operation elasticity, high cold energy utilization rate and capability of being matched with the LNG gasification amount of the station is designed. The LNG cold energy recycling system only utilizes one refrigerant to realize the cooling of the freeze-drying boxes and the cold traps of equipment with different refrigeration requirements, so that a set of process system can realize the freeze-drying of all types of materials; and the refrigeration coupling of the LNG and the LNG can be realized by a set of voltage shrinking deviceAnd when the LNG cold energy is insufficient, the electric compression device is used for supplementing cold, so that the working condition adaptability is high, and the cold energy utilization rate is high.
The invention is realized at least by one of the following technical schemes.
Based on CO 2 The LNG cold energy of the refrigerant is used for a freeze-drying process system and comprises an LNG gasification system, a cold energy recycling system and a voltage condensation refrigeration system;
the LNG gasification system comprises an LNG storage tank, an air temperature type gasifier, a first heat exchanger and a first auxiliary heater; the input end of the first heat exchanger is communicated with the output end of the LNG storage tank, the output end of the first heat exchanger is connected with the input end of the first auxiliary heat exchanger in series, and the first heat exchanger is connected with the air temperature type gasifier in parallel after the first heat exchanger is connected in series;
the cold energy recycling system is used for transmitting cold energy to a receiving end, the receiving end is a refrigerating unit, and the cold energy recycling system comprises a liquid refrigerant storage tank, a refrigerant pump, a freeze-drying box, a cold trap, a second auxiliary heater, a compressor and a third heat exchanger; the input end of the liquid refrigerant storage tank is communicated with the output end of the first heat exchanger and is connected in series with the refrigerant pump; after being connected in series, the refrigerant pump is connected with two branches, and is respectively communicated with the input end of the freeze-drying box and the output end of the cold trap, and the cold trap, the second auxiliary heater, the compressor and the third heat exchanger are sequentially connected in series, then are connected with the freeze-drying box in parallel, and are communicated with the input end of the first heat exchanger after being connected in parallel;
the voltage reduction refrigeration system comprises a second heat exchanger, a refrigeration compressor, a condenser and a refrigeration expansion valve; the second heat exchanger, the refrigeration compressor, the condenser and the refrigeration expansion valve are connected in sequence; the second heat exchanger is connected with the first heat exchanger in parallel, the input end of the second heat exchanger is connected with the output end of the freeze-drying box connected with the cold trap in parallel, and the output end of the second heat exchanger is communicated with the input end of the liquid refrigerant storage tank.
Further, the LNG gasification system further comprises a pressure regulator and a flowmeter, and the output end of the air-temperature gasifier and the output end of the first auxiliary heater are connected with the pressure regulator and the flowmeter.
Further, a second regulating valve is arranged between the LNG storage tank and the first heat exchanger to regulate the flow of LNG, and a first regulating valve is arranged between the air temperature type gasifier and the LNG storage tank to realize seamless switching of working conditions. When the system works normally, the LNG adopts a gasification mode that the first heat exchanger and the first auxiliary heat exchanger are sequentially reheated to realize cold energy utilization, and when the LNG cold energy utilization fails, the air temperature type gasifier can play a role in safety risk avoidance.
Further, a fifth regulating valve for controlling flow circulation, a sixth regulating valve for controlling on-off of the branch and a fourth regulating valve are arranged between the first heat exchanger and the second heat exchanger. The fourth, fifth and sixth regulator valve switches or openings depend on LNG flow.
Further, the heat exchange medium in the first heat exchanger, the second heat exchanger, the freeze-drying box and the cold trap is the same refrigerant CO 2 。
Further, the second heat exchanger has the functional characteristics of an evaporator.
Further, a pressure reducing valve is provided on a branch line connecting the refrigerant pump and the cold trap.
Based on CO 2 The LNG cold energy of the refrigerant is used for the freeze-drying method of the freeze-drying process system, and the method comprises the following steps:
LNG from the LNG storage tank enters a first heat exchanger to exchange heat with a refrigerant, is further heated by a first auxiliary heater after gasified and heated, and finally enters a pipe network after being regulated by a flowmeter, wherein a second regulating valve regulates the flow of the inflowing LNG and cuts off the inflowing LNG in an emergency;
low-temperature refrigerant CO from liquid refrigerant storage tank 2 Dividing into two parts, wherein one part flows into a freeze-drying box to exchange heat with materials in the freeze-drying box to pre-freeze the materials, and the other part flows into a cold trap of cooling equipment with lower temperature requirement to be trapped by water vapor to raise the temperature after being depressurized and cooled by a pressure reducing valve, so as to lead the refrigerant CO to be 2 Circulating, collecting water vapor, continuously heating in a second auxiliary heater, heating in a compressor, finally exchanging heat with a condensing agent solution in a third heat exchanger, merging with the former strand, dividing into two strands, respectively performing LNG refrigeration cycle and voltage reduction refrigeration cycle, and finally returning the two strands of refrigerants to a liquid refrigerant storage tank after respectively exchanging heat so as to achieve the purposeAnd (5) circulating.
Wherein, according to the material type difference, the temperature of the freeze-drying box is about minus 30 ℃ to minus 20 ℃, and the cold trap temperature mainly has several grades of about minus 45 ℃, about minus 60 ℃ and about minus 80 ℃. The process system can control the refrigerant CO entering the freeze-drying box by setting the outlet temperature of the hot flow of the first heat exchanger 2 Temperature and outlet pressure of the pressure reducing valve are controlled to control refrigerant CO entering the cold trap 2 Temperature of the refrigerant CO 2 The refrigeration system is used for exchanging heat with LNG and is coupled with a voltage condensation refrigeration system to provide different amounts of cold energy with different temperature levels for the freeze-drying refrigeration system, so that one set of process system can meet the freeze-drying requirement of all types of materials.
Further, if the air consumption requirement of the downstream user is large and the LNG output is sufficient, the refrigerant CO flowing in the second heat exchanger in the voltage reduction refrigeration system is controlled 2 The fourth regulating valve opening of the flow can be reduced or not started; if the gas consumption of the downstream users is smaller, the refrigerant CO flowing in the second heat exchanger in the voltage condensation refrigeration system is controlled when the LNG output is insufficient or the electricity price of the station area is in low valley 2 The opening degree of the valve of the fourth regulating valve of the flow can be increased to control the refrigerant CO flowing in the first heat exchanger 2 The fifth regulator valve opening of the flow may be reduced.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention uses a refrigerant CO 2 The heat exchange with LNG is realized to provide different amounts of cold energy with different temperature levels for the freeze-drying refrigerating system, so that one set of process system can meet the freeze-drying requirement of all types of materials.
2. The LNG cold energy utilization system only adopts one refrigerant CO 2 The refrigerant is simple to manage and has wide application range.
3. According to the LNG gasification process, the voltage shrinkage system and the LNG cold energy recycling system are used for coupling, so that the problem of fluctuation of LNG gasification quantity is solved by supplementing cold or utilizing valley electricity, normal operation of the process is realized, the cost is reduced, and the operation flexibility of the process is improved.
4. The invention couples the plurality of compressors, heat exchangers and other devices to make the refrigerantCO 2 And the system can be recycled to improve the energy utilization rate of the system.
5. The invention can solve the fluctuation problem of the gasification amount of the LNG satellite station, has large refrigeration amount and few types of refrigerants and is convenient for refrigerant management. The cold energy utilization rate of the whole system is 98.8 percent,The efficiency was 35.8%.
Drawings
FIG. 1 shows a CO-based system according to an embodiment of the present invention 2 LNG cold energy of the refrigerant is used for a freeze-drying process system schematic diagram;
FIG. 2 is a schematic diagram of a process system when the LNG vaporization quantity is sufficient in an embodiment of the present invention;
fig. 3 is a schematic diagram of a process system when LNG vaporization is insufficient or electricity prices are in low valleys in a field station area according to an embodiment of the present invention.
The figure shows: the system comprises a 1-LNG storage tank, a 2-first regulating valve, a 3-air temperature gasifier, a 4-pressure regulator, a 5-flowmeter, a 6-second regulating valve, a 7-first heat exchanger, a 8-third regulating valve, a 9-first auxiliary heater, a 10-first stop valve, a 11-second stop valve, a 12-third stop valve, a 13-second heat exchanger, a 14-fourth regulating valve, a 15-fifth regulating valve, a 16-sixth regulating valve, a 17-liquid refrigerant storage tank, a 18-refrigerant flow regulating valve, a 19-refrigerant pump, a 20-fourth stop valve, a 21-freeze dryer, a 22-fifth stop valve, a 23-pressure reducing valve, a 24-cold trap, a 25-sixth stop valve, a 26-second auxiliary heater, a 27-compressor, a 28-seventh stop valve, a 29-third heat exchanger, a 30-eighth stop valve, a 31-refrigeration compressor, a 32-ninth stop valve, a 33-condenser, a 34-refrigeration expansion valve, a 35-tenth stop valve and a 36-ice maker.
Detailed Description
For a better understanding of the present invention, reference will now be made to the following description of the invention taken in conjunction with the accompanying drawings and examples, which are included to illustrate and not limit the scope of the invention.
Example 1
As shown in FIG. 1, the invention provides a method based on CO 2 LNG cold energy of refrigerant is used for freeze-drying process system, includesLNG gasification system, cold energy recycle system, voltage shrink refrigeration system.
The LNG gasification system comprises an LNG storage tank 1, an air temperature type gasifier 3, a first heat exchanger 7, a first auxiliary heater 9, a pressure regulator 4 and a flowmeter 5, wherein a heat exchange medium in the first heat exchanger 7 is a refrigerant CO 2 The first heat exchanger 7 is connected in series with the first auxiliary heater 9, then is connected in parallel with the air temperature type gasifier 3, is communicated with the output end of the LNG storage tank 1 together, the air temperature type gasifier 3 and the output end of the first auxiliary heater 9 are connected with the flowmeter 5 through the pressure regulator 4, finally enter the pipe network after being regulated, wherein the inlet side of the first heat exchanger 7 is provided with the second regulating valve 6, the outlet side is provided with the third regulating valve 8, the effect of working condition switching is achieved, and the input end of the pressure regulator 4 is communicated with the first stop valve 10 for realizing emergency cutting of working conditions.
A second regulating valve 6 is provided between the first heat exchanger 7 and the LNG tank 1 so that the gasification amount of the LNG delivered from the station can be appropriately regulated according to the use amount of the natural gas by the downstream user. When the downstream user has large air consumption and exceeds the supercooling energy operation load, the air-temperature type gasifier 3 is started to assist gasification and refrigerant CO 2 The heat exchange gasification is performed simultaneously, thereby ensuring sufficient supply of LNG. LNG from the LNG storage tank 1 enters two paths of gasification systems respectively, one path of LNG is transported to a downstream user through a pipe network after being gasified in an auxiliary way by the air-temperature type gasifier 3, and the other path of LNG is sent to the downstream user after being reheated to a preset temperature by the first auxiliary heater 9, wherein the refrigerant CO processed by the first heat exchanger 7 is sent to the downstream user 2 The LNG cold energy is carried, and the LNG cold energy can be used by a cold energy recycling system, and when the LNG gasification amount is high, the recycled cold energy is correspondingly increased.
The cold energy recycling system is used for transmitting cold energy to a receiving end, and the receiving end is a refrigerating unit and comprises a liquid refrigerant storage tank 17, a refrigerant pump 19, a freeze-drying box 21, a cold trap 24, a second auxiliary heater 26, a compressor 27 and a third heat exchanger 29. The input end of the liquid refrigerant storage tank 17 is communicated with the output end of the first heat exchanger 7 and is connected in series with the refrigerant pump 19; after being connected in series, the refrigerant pump 9 is connected with two branches, the two branches are respectively communicated with the input end of the freeze-drying box 21 and the input end of the cold trap 24, and the cold trap 24 is connected in series with the second auxiliary heater 26, the compressor 27 and the third heat exchanger 29 in sequence, then is connected with the freeze-drying box 21 in parallel, and is communicated with the input end of the first heat exchanger 7 after being connected in parallel.
Low temperature refrigerant CO from liquid refrigerant reservoir 17 2 Divided into two parts, one part flows into a freeze-drying box 21 to exchange heat with the material in the freeze-drying box 21 to pre-freeze the material, the other part flows into a cold trap 24 of a cooling device with lower temperature requirement after being reduced in pressure and temperature by a pressure reducing valve 23 to be trapped by water vapor and heated, and the purpose of the refrigerant CO is that 2 Circulating, collecting water vapor, continuously heating, pressurizing in a compressor 27, exchanging heat with condensed water solution in a third heat exchanger 29, and cooling with refrigerant CO flowing out of the freeze-drying tank 21 2 Merging, dividing into two paths, respectively performing LNG refrigeration cycle and voltage reduction refrigeration cycle, and finally returning the two paths of refrigerants to the liquid refrigerant storage tank 17 after respectively exchanging heat so as to achieve circulation. The compressor 27 is used differently from the refrigeration compressor 31 in a voltage-compression refrigeration system, where CO is achieved mainly in combination with the second auxiliary heater 26 and the third heat exchanger 29 2 And the refrigerant circulates.
The electric compression refrigeration system comprises a second heat exchanger 13, a refrigeration compressor 31, a condenser 33 and a refrigeration expansion valve 34; the second heat exchanger 13, the refrigeration compressor 31, the condenser 33 and the refrigeration expansion valve 34 are sequentially connected into a loop; and the second heat exchanger 13 is connected in parallel with the first heat exchanger 7, and the input end of the second heat exchanger 13 is connected with the output end of the freeze-drying box 21 connected in parallel with the cold trap 24, and the output end is communicated with the input end of the liquid refrigerant storage tank 17. A fourth control valve 14 for switching on and off branches is arranged between the second heat exchanger 13 and the first heat exchanger 7, wherein a third shut-off valve 12 for emergency shut-off is arranged at the output of the second heat exchanger 13; a fifth control valve 15 for controlling the flow and a sixth control valve 16 for switching the branch are arranged between the first heat exchanger 7 and the second heat exchanger 13, wherein the second shut-off valve 11 is used for emergency shut-off.
The pressure can be reduced by the pressure reducing valve 23 to reduce CO 2 The refrigerant enters a cold trap 24 of cooling equipment with lower temperature requirements after the temperature of the refrigerant is reduced, and then water vapor is trapped; the refrigeration compressor 31 may be usedTo increase the pressure of the compressed refrigerant, and then to be matched with the condenser 33 and the refrigeration expansion valve 34 to achieve the refrigeration function; the compressor 27 is used for raising the refrigerant CO 2 The pressure achieves the effect of circulating the pressure.
If the gas consumption requirement of the downstream user is large and the LNG output is sufficient, controlling the refrigerant CO flowing in the second heat exchanger 13 in the voltage reduction refrigeration system 2 The valve opening of the fourth regulator valve 14 of the flow rate may be reduced or not activated; if the gas consumption of the downstream users is smaller, the refrigerant CO flowing in the second heat exchanger 13 in the voltage condensation refrigeration system is controlled when the LNG output is insufficient or the electricity price of the station area is in low valley 2 The opening of the fourth regulating valve 14 of the flow can be increased to control the refrigerant CO flowing in the first heat exchanger 7 2 The valve opening of the fifth regulating valve 15 of the flow rate may be reduced. The refrigeration compressor 31 is different from the compressor 27 in the LNG cold energy recovery system in use, and is mainly used in combination with the ninth stop valve 32, the condenser 33, and the refrigeration expansion valve 34 to achieve the refrigeration and make-up function, and the second heat exchanger 13 has the functional characteristics of an evaporator.
The process system can control the refrigerant CO entering the freeze-drying box 21 by setting the outlet temperature of the hot flow of the first heat exchanger 7 2 Temperature, the refrigerant CO entering the cold trap 24 is controlled by controlling the outlet pressure of the pressure reducing valve 23 2 Temperature of the refrigerant CO 2 The refrigeration system is used for exchanging heat with LNG and is coupled with a voltage condensation refrigeration system to provide different amounts of cold energy with different temperature levels for the freeze-drying refrigeration system, so that one set of process system can meet the freeze-drying requirement of all types of materials.
Example 2
Taking an LNG station as an example, the consumption of fuel gas is low in the period of 1-2 months, the gas consumption of LNG is rapidly increased in the period of 2-3 months, the gas consumption is further increased after 6 months, the gas consumption of the LNG station is taken as a reference for 3-6 months, the whole process scale is designed, and the daily gas consumption is about 40000m 3 。
One of the above is based on CO 2 LNG cold energy of the refrigerant is used for a freeze-drying method, and the method comprises the following steps:
the LNG coming out of the LNG storage tank 1 enters under the condition of about 30bar and 162 DEG CThe first heat exchanger 7, LNG is first mixed with refrigerant CO of 15bar at minus 20 DEG C 2 After the heat exchange is heated to-30 ℃, the LNG flows into the first auxiliary heater 9 to be reheated to be heated to more than 5 ℃ and then is sent into a pipe network through the flowmeter 5, wherein the flow of the LNG flowing into the first heat exchanger 7 is regulated by the second regulating valve 6; (the limitation of temperature in this embodiment is only a specific example and does not limit the scope of protection)
Refrigerant CO in the first heat exchanger 7 2 Cooling by heat exchange, condensing to-30deg.C, and introducing into LNG cold energy freeze-drying system, and cooling by refrigerant CO in the second heat exchanger 13 2 Exchanges heat with the low-temperature refrigerant at minus 33 ℃ at the outlet of the refrigeration expansion valve 34, and is cooled to minus 30 ℃ and then is merged with the first refrigerant to enter the LNG cold energy freeze-drying system.
15bar from the liquid refrigerant tank 17, low temperature refrigerant CO at-30 DEG C 2 Dividing into two parts, wherein one part flows into a freeze-drying box 21 to exchange heat with the material in the freeze-drying box 21 to pre-freeze the material and then heat the material to-20 ℃, the other part is reduced in pressure and temperature to 6.6bar through a pressure reducing valve 23, and then flows into a cold trap 24 of a cooling device with lower temperature requirement after the material is reduced in pressure and cooled to-50 ℃, and then water vapor is trapped and heat the material to-40 ℃, so as to lead the refrigerant CO to be 2 Circulating, namely, after water vapor is trapped, the water vapor enters the second auxiliary heater 26 to be continuously heated to 20 ℃, then enters the compressor 27 to be boosted and heated to 99 ℃, finally, the temperature is reduced to minus 20 ℃ after heat exchange between the third heat exchanger 29 and the condensing agent solution, the water vapor is converged with the former strand, and then is divided into two strands for LNG refrigeration cycle and voltage compression refrigeration cycle respectively, and finally, the two paths of refrigerants are returned to the liquid refrigerant storage tank after heat exchange respectively to achieve circulation.
In the voltage reduction refrigeration system, the high-temperature refrigerant from the refrigeration compressor 31 enters the condenser 33 for cooling, is condensed to the temperature of minus 20 ℃ and then is sent into the refrigeration expansion valve 34 for partial gasification, and finally, the refrigerant enters the second heat exchanger 13 and the refrigerant CO 2 And the heat exchange and evaporation are carried out, and the refrigerant returns to the refrigeration compressor 31 to complete the cycle.
Wherein, according to the material type difference, the temperature of the freeze-drying box is about minus 30 ℃ to minus 20 ℃, and the cold trap temperature mainly has several grades of about minus 45 ℃, about minus 60 ℃ and about minus 80 ℃. In this example, the freeze-drying box temperature range is-30 to-20℃and the cold trap temperature range is-50 to-40 ℃.
In this embodiment, the compressor with the power of 5.28kW and LNG with the mass flow rate of 1t/h in the compression system can provide 78kW of cooling power to the freeze-drying tank 21, and the cooling power of 178 kW of cooling power to the cold trap 24, and the gasification of 1t/h of LNG is equivalent to the saving of 53.5kWh of electric energy. The whole process flowThe efficiency is 35.8%, and the cold energy utilization rate is as high as 98.8%.
Example 3
As shown in FIG. 2, the invention provides a method based on CO 2 The LNG cold energy of the refrigerant is used for a freeze-drying process system, and comprises an LNG gasification system and a cold energy recycling system.
The LNG gasification system comprises an LNG storage tank 1, an air temperature type gasifier 3, a first heat exchanger 7, a first auxiliary heater 9, a pressure regulator 4 and a flowmeter 5, wherein a heat exchange medium in the first heat exchanger 7 is a refrigerant CO 2 The first heat exchanger 7 is connected with the first auxiliary heater 9 in series, then is connected with the air temperature type gasifier 3 in parallel, is communicated with the output end of the LNG storage tank 1 together, the output ends of the air temperature type gasifier 3 and the first auxiliary heater 9 are connected with the flowmeter 5 through the pressure regulator 4, and finally enter a pipe network after being regulated, wherein the inlet side of the first heat exchanger 7 is provided with the second regulating valve 6, the outlet side is provided with the third regulating valve 8, the effect of working condition switching is achieved, and the input end of the pressure regulator 4 is communicated with the first stop valve 10 for realizing emergency cutting of working conditions;
a second regulating valve 6 is provided between the first heat exchanger 7 and the LNG tank 1 so that the gasification amount of the LNG delivered from the station can be appropriately regulated according to the use amount of the natural gas by the downstream user.
When the gas consumption requirement of the downstream user is large and the LNG output is sufficient, the process system is not provided with a voltage reduction refrigeration system, and the air temperature type gasifier 3 is utilized for assisting gasification to ensure the gas consumption requirement of the downstream user.
The cold energy recycling system is used for transmitting cold energy to a receiving end, and the receiving end is a refrigerating unit and comprises a liquid refrigerant storage tank 17, a refrigerant pump 19, a freeze-drying box 21, a cold trap 24, an ice maker 36, a compressor 27 and a third heat exchanger 29. The input end of the liquid refrigerant storage tank 17 is communicated with the output end of the first heat exchanger 7 and is connected in series with the refrigerant pump 19; after being connected in series, the refrigerant pump 9 is connected with two branches, the two branches are respectively communicated with the input end of the freeze-drying box 21 and the input end of the cold trap 24, and the cold trap 24 is connected in series with the ice maker 36, the compressor 27 and the third heat exchanger 29 in sequence, then is connected with the freeze-drying box 21 in parallel, and is communicated with the input end of the first heat exchanger 7 after being connected in parallel; the system operates in the same manner as in example 2. The difference is that because LNG is cold enough, when the freeze-dried product yield is greater than market demand, excess cold can be sent to ice maker 36 for ice making to increase cold energy utilization.
Example 4
As shown in FIG. 3, the invention provides a method based on CO 2 The LNG cold energy of the refrigerant is used for a freeze-drying process system and comprises an LNG gasification system, a cold energy recycling system and a voltage condensation refrigeration system.
The LNG gasification system comprises an LNG storage tank 1, a first heat exchanger 7, a first auxiliary heater 9, a pressure regulator 4 and a flowmeter 5, wherein a heat exchange medium in the first heat exchanger 7 is a refrigerant CO 2 The first heat exchanger 7 is connected in series with the first auxiliary heat exchanger 9, is communicated with the output end of the LNG storage tank 1, the output end of the first auxiliary heat exchanger 9 is connected with the flowmeter 5 through the pressure regulator 4, and finally enters a pipe network after being regulated, wherein a second regulating valve 6 is arranged at the inlet of the first heat exchanger 7, a third regulating valve 8 is arranged at the outlet of the first heat exchanger, the effect of switching working conditions is achieved, and the input end of the pressure regulator 4 is communicated with a first stop valve 10 for realizing emergency cutting of the working conditions;
a second regulating valve 6 is provided between the first heat exchanger 7 and the LNG tank 1 so that the gasification amount of the LNG delivered from the station can be appropriately regulated according to the use amount of the natural gas by the downstream user.
When the gas consumption requirement of the downstream user is smaller and the LNG output is insufficient, the process system only needs CO 2 The refrigerant exchanges heat with the LNG at one stage to gasify the LNG.
The cold energy recycling system is used for transmitting cold energy to a receiving end, and the receiving end is a refrigerating unit and comprises a second heat exchanger 13, a liquid refrigerant storage tank 17, a refrigerant pump 19, a freeze-drying box 21, a cold trap 24, a second auxiliary heater 26, a compressor 27 and a third heat exchanger 29. The input end of the liquid refrigerant storage tank 17 is communicated with the output end of the first heat exchanger 7 and is connected in series with the refrigerant pump 19; after the series connection, the refrigerant pump 9 is connected with two branches, the two branches are respectively communicated with the input end of the freeze-drying box 21 and the input end of the cold trap 24, the cold trap 24 is connected with the second auxiliary heater 26, the compressor 27 and the third heat exchanger 29 in series in sequence, then connected with the freeze-drying box 21 in parallel, and after being connected in parallel, communicated with the input end of the first heat exchanger 7, and the system operates in the same manner as in the embodiment 2.
The electric compression refrigeration system comprises a second heat exchanger 13, a refrigeration compressor 31, a condenser 33 and a refrigeration expansion valve 34; the second heat exchanger 13, the refrigeration compressor 31, the condenser 33 and the refrigeration expansion valve 34 are sequentially connected into a loop; and the second heat exchanger 13 is connected in parallel with the first heat exchanger 7, and the input end of the second heat exchanger 13 is connected with the output end of the freeze-drying box 21 connected in parallel with the cold trap 24, and the output end is communicated with the input end of the liquid refrigerant storage tank 17. The electric compression refrigeration system operates in the same manner as in example 1. At the moment, the electric compression refrigeration system is used for supplementing cold, and normal supply of freeze-dried products in the market is guaranteed. In particular, when the electricity price of the site area is in a valley, the voltage reduction refrigeration system can be opened, and valley electricity is utilized for refrigeration so as to save the cost.
The above examples of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (10)
1. Based on CO 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: comprises an LNG gasification system, a cold energy recycling system and a voltage shrinkage refrigeration system,
the LNG gasification system comprises an LNG storage tank (1), an air temperature type gasifier (3), a first heat exchanger (7) and a first auxiliary heater (9); the input end of the first heat exchanger (7) is communicated with the output end of the LNG storage tank (1), the output end of the first heat exchanger (7) is connected with the input end of the first auxiliary heat exchanger (9) in series, and the connected first heat exchanger is connected with the air temperature type gasifier (3) in parallel;
the cold energy recycling system is used for transmitting cold energy to the receiving end and comprises a first heat exchanger (7), a liquid refrigerant storage tank (17), a refrigerant pump (19), a freeze-drying box (21), a cold trap (24), a second auxiliary heater (26), a compressor (27) and a third heat exchanger (29); the input end of the liquid refrigerant storage tank (17) is communicated with the output end of the first heat exchanger (7) and is connected in series with the refrigerant pump (19); after being connected in series, the refrigerant pump (19) is connected with two branches, and is respectively communicated with the input end of the freeze-drying box (21) and the output end of the cold trap (24), and the cold trap (24) is connected in series with the second auxiliary heater (26), the compressor (27) and the third heat exchanger (29) in sequence, then is connected with the freeze-drying box (21) in parallel, and is communicated with the input end of the first heat exchanger (7) after being connected in parallel;
the voltage reduction refrigeration system comprises a second heat exchanger (13), a refrigeration compressor (31), a condenser (33) and a refrigeration expansion valve (34); the second heat exchanger (13), the refrigeration compressor (31), the condenser (33) and the refrigeration expansion valve (34) are connected into a loop; the second heat exchanger (13) is connected with the first heat exchanger (7) in parallel, the input end of the second heat exchanger (13) is connected with the output end of the freeze-drying box (21) connected with the cold trap (24) in parallel, and the output end is communicated with the input end of the liquid refrigerant storage tank (17).
2. A CO-based process according to claim 1 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: the LNG gasification system further comprises a pressure regulator (4) and a flowmeter (5), wherein the output end of the air-temperature gasifier (3) and the output end of the first auxiliary heater (9) are connected with the pressure regulator (4) and the flowmeter (5).
3. A CO-based process according to claim 1 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: a second heat exchanger (7) is arranged between the LNG storage tank (1)The air temperature type LNG storage tank comprises an air temperature type gasifier (3) and an LNG storage tank (1), wherein the air temperature type gasifier is characterized in that an adjusting valve (6) is used for adjusting the flow of LNG, and a first adjusting valve (2) is arranged between the air temperature type gasifier (3) and the LNG storage tank (1) and used for realizing seamless switching of working conditions.
4. A CO-based process according to claim 1 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: a fifth regulating valve (15) for controlling the flow circulation is arranged between the first heat exchanger (7) and the second heat exchanger (13).
5. A CO-based process according to claim 1 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: a sixth regulating valve (16) and a fourth regulating valve (14) for controlling the on-off of the branch are arranged between the first heat exchanger (7) and the second heat exchanger (13).
6. A CO-based process according to claim 1 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: the receiving end is a refrigerating unit.
7. A CO-based process according to claim 1 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: the heat exchange media in the first heat exchanger (7), the second heat exchanger (13), the freeze-drying box (21) and the cold trap (24) are the same refrigerant CO 2 。
8. A CO-based process according to claim 1 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: the second heat exchanger (13) has the functional characteristics of an evaporator.
9. A CO-based catalyst according to any one of claims 1-8 2 LNG cold energy of refrigerant is used for freeze-drying process system, its characterized in that: a pressure reducing valve (23) is provided on a branch line connecting the refrigerant pump (19) and the cold trap (24).
10. Based on CO 2 Method for freeze-drying LNG cold energy of refrigerantThe implementation of the system according to any of claims 1-9, comprising the steps of:
LNG from the LNG storage tank (1) enters a first heat exchanger (7) to exchange heat with a refrigerant, is gasified and heated, and then enters a pipe network after being further heated by a first auxiliary heater (9);
the low-temperature refrigerant from the liquid refrigerant storage tank (17) is divided into two parts, one part flows into the freeze-drying box (21) to exchange heat with the material in the freeze-drying box (21) to pre-freeze the material, the other part flows into a cold trap (24) with a lower temperature requirement after being depressurized and cooled to be trapped by water vapor and then to be heated, and in order to enable the refrigerant CO to be cooled 2 Circulating, collecting water vapor, continuously heating, then entering a second auxiliary heater (26), entering a compressor (27), boosting and heating, finally exchanging heat with a condensing agent solution in a third heat exchanger (29), merging with the former strand, dividing into two strands, respectively performing LNG refrigeration cycle and voltage reduction refrigeration cycle, and finally returning the two paths of refrigerants to a liquid refrigerant storage tank (17) after respectively exchanging heat.
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