CN109931732A - A kind of high-adaptability cold-storage multi-stage temperature refrigerator system of cascade utilization LNG cold energy - Google Patents

Abstract

The present invention relates to a kind of multi-stage temperature refrigerator system, the high-adaptability cold-storage multi-stage temperature refrigerator system of especially a kind of cascade utilization LNG cold energy.The present invention realizes the cascade utilization to LNG cold energy, improves LNG cold energy use rate；According to the automatic control system of optimization, the flow of refrigerant can be adjusted in real time to achieve the purpose that control temperature of ice house；Any collocation operation that a variety of cooling supply modes are realized by the opening and closing of solenoid valve solves the stability problem of the freezer operation using LNG refrigeration；Cold-storage can be carried out by cold accumulation system, the cold energy of storage is released again in low peak period or the high electricity price of natural gas supply, reduces the operating cost of system；It is added to gas-liquid separator, ensure that the normal operation of refrigerant pump and the higher heat exchange efficiency of evaporator；The refrigerant R32 and liquefied ammonia of selection have very high friendly to environment；There is freezing by change of state using refrigerant, can make full use of refrigerant gasification latent heat refrigeration, reduce cold medium flux.

Description

A high-adaptability cold storage multi-temperature cold storage system using LNG cold energy in cascade

Technical field

The invention relates to a multi-temperature cold storage system, in particular to a high-adaptability cold storage multi-temperature cold storage system utilizing LNG cold energy in steps.

Background technique

Since natural gas emits very few pollutants during the combustion process, the demand for natural gas in my country is growing rapidly at present, and natural gas is generally liquefied into LNG for the convenience of transportation. LNG will be vaporized at the vaporization station before being supplied to users. During this process, about 830KJ/kg of cold energy will be released, and this part of the cold energy will generally be taken away by air or sea water, which not only causes a great waste of energy It will also have a certain impact on the environment. The current LNG cold energy utilization methods mainly include cold energy power generation, air separation, low temperature pulverization, light hydrocarbon recovery, production of liquid _CO2 or dry ice, seawater desalination, ice making, cold storage, air conditioning, etc. In order to improve the utilization rate of LNG cold energy, it is necessary to use the LNG cold energy in cascade, that is, a variety of cold energy utilization methods with different temperature requirements are used to utilize the LNG cold energy in turn, and it is difficult to find in actual industrial production. An engineering example to realize the cascade utilization of cold energy.

Cold storage is a large power consumer, and the power consumption of cold storage accounts for more than 50% of the operating cost of the entire cold storage. Due to the different cold storage temperatures required by different products, the cold storage is often designed as a multi-temperature cold storage during construction to meet the refrigeration needs of different products. The temperature range of the cold storage is -60℃-5℃. If the cold energy of LNG is applied to the multi-temperature cold storage, the cascade utilization of LNG cold energy can be realized and the utilization efficiency of LNG cold energy can be improved. At present, the existing problems of using LNG cold energy in cold storage systems include: single cooling method, low adaptability of the system to load changes; single-stage heat exchange between refrigerant and LNG, low utilization rate of LNG cold energy; no cold storage device added, LNG supply cannot be It is difficult to adjust when it is stable; the degree of automation of the cold storage is not high; the refrigerant adopts non-phase-change refrigeration, and the refrigerant flow is large;

SUMMARY OF THE INVENTION

In order to overcome the problems of insufficient utilization of LNG cold energy, weak adaptability of the system to changes in load and LNG supply, and high power consumption caused by electric compression refrigeration, the present invention proposes a cascade utilization of LNG cold energy with high adaptability Warm and cold storage system. The invention realizes the cascade utilization of LNG cold energy and improves the utilization rate of LNG cold energy; according to the optimized automatic control system, not only the flow of the refrigerant can be adjusted in real time to achieve the purpose of controlling the temperature of the cold storage, but also various cooling modes can be realized. At the same time, it solves the problem of the stability of the operation of the cold storage using LNG refrigeration; in the peak period of natural gas supply or when the electricity price is low, the cold storage system designed by the present invention can be used for cold storage, and in the low peak period of natural gas supply or the high electricity price The stored cold energy is released from time to time, reducing the operating cost of the system.

The technical scheme adopted in the present invention is:

A highly adaptable multi-temperature cold storage system that can make full use of LNG cold energy, which includes LNG gasification system, freezing-ultra-low temperature parallel cold storage system, R32 circulating refrigeration system utilizing LNG cold energy, R32 cold storage system, and R32 vapor compression refrigeration cycle system, refrigerator system, ammonia cycle refrigeration system utilizing LNG cold energy, ice cold storage system, ammonia vapor compression refrigeration cycle system; among them,

(1) The above-mentioned LNG gasification system, including LNG-R32 heat exchanger, LNG-ammonia heat exchanger, thermal expansion valve, solenoid valve, check valve, natural gas transportation pipeline network, described LNG-R32 heat exchanger The refrigerant input and output pipelines of the LNG-liquid ammonia heat exchanger are connected to the R32 circulating refrigeration system using LNG cold energy, and the refrigerant input and output pipelines of the LNG-liquid ammonia heat exchanger are connected to the liquid ammonia circulating refrigeration system using LNG cold energy. The thermal expansion valve can adjust the LNG flow into the heat exchanger according to the set heat exchange temperature, the solenoid valve can adjust the LNG heat exchange mode according to the working mode of the cold storage, and the check valve can prevent the low-pressure pipeline refrigerant. backflow.

(2) the above-mentioned freezing-ultra-low temperature parallel cold storage system, including the solenoid valve and the temperature controller connecting the three-way valve outlet, the thermal expansion valve connecting the electromagnetic valve outlet of the freezer pipeline, the freezer connecting the thermal expansion valve outlet, and the freezing The pressure regulating valve at the outlet of the warehouse, the multi-port valve connected to the outlet of the pressure regulating valve, the throttle valve connected to the outlet of the solenoid valve of the ultra-low temperature warehouse pipeline, the gas-liquid separator connected to the outlet of the throttle valve, the solenoid connected to the gas-phase outlet of the gas-liquid separator Valves, check valves and multi-port valves, thermal expansion valve connected to the liquid phase outlet of the gas-liquid separator, ultra-low temperature storage connected to the outlet of the thermal expansion valve, solenoid valve connected to the outlet of the ultra-low temperature storage, multi-port valve connected to the outlet of the electromagnetic valve, all The gas-liquid separator is used to ensure that all the refrigerant entering the evaporator exists in the form of liquid phase, the solenoid valve and the temperature sensor are used to adjust the temperature stability of the cold storage, the thermal expansion valve is used to adjust the refrigerant flow, and the throttle valve is used for In order to cool the refrigerant, the pressure regulating valve is used to reduce the pressure of the refrigerant.

(3) The above-mentioned R32 circulating refrigeration system utilizing LNG cold energy includes the LNG-R32 heat exchanger connected to the outlet of the multi-port valve, the gas-liquid separator connected to the outlet of the LNG-R32 heat exchanger, and the gas-liquid separator gas-phase outlet. The solenoid valve, check valve and multi-way valve are connected to the refrigerant pump of the liquid phase outlet of the gas-liquid separator, and the refrigeration-ultra-low temperature parallel cold storage system is connected to the outlet of the refrigerant pump. The LNG-R32 heat exchanger is used for the refrigerant to obtain LNG cold energy. , the gas-liquid separator is used to ensure that all the refrigerant entering the refrigerant pump exists in the form of liquid phase.

(4) The above-mentioned R32 cold storage system includes the R32 low temperature storage tank, the high pressure float valve and the liquid level controller connected to the liquid phase inlet of the R32 low temperature storage tank, the check valve and the solenoid valve connected to the gas phase inlet of the R32 low temperature storage tank, and the R32 The refrigerant pump at the liquid phase outlet of the low-temperature storage tank is connected to the refrigeration-ultra-low temperature parallel cold storage system connected to the outlet of the refrigerant pump. The liquid level controller can monitor and adjust the storage capacity of R32 in the low-temperature storage tank in real time to ensure that it does not exceed the warning line at the same time. Store enough low-temperature R32 to use when the cold storage cycle is turned on for cooling.

(5) The above-mentioned R32 vapor compression refrigeration cycle system includes a solenoid valve connected to the outlet of the multi-port valve, a compressor connected to the outlet of the solenoid valve, a condenser connected to the outlet of the compressor, a throttle valve and a check valve connected to the outlet of the condenser , Connect the check valve and solenoid valve of the gas-liquid separator gas outlet, and connect the cold storage system of the liquid-phase outlet of the gas-liquid separator, the gas-liquid separator is used to ensure that all the refrigerant entering the cold storage system exists in the form of liquid phase.

(6) The above-mentioned refrigerator system includes a solenoid valve and a temperature controller connected to the outlet of the three-way valve, a thermal expansion valve connected to the outlet of the electromagnetic valve, a refrigerator connected to the outlet of the thermal expansion valve, a solenoid valve connected to the outlet of the refrigerator, and a multi-function valve. The through valve, the solenoid valve and the temperature sensor are used to adjust the temperature stability of the cold storage, and the thermal expansion valve is used to adjust the refrigerant flow.

(7) the above-mentioned ammonia cycle refrigeration system utilizing LNG cold energy, including the LNG-ammonia heat exchanger connected to the outlet of the three-way valve, the gas-liquid separator connected to the outlet of the LNG-ammonia heat exchanger, and the gas-liquid separator gas-phase outlet connected The solenoid valve and check valve are connected to the refrigerant pump of the liquid phase outlet of the gas-liquid separator, and the refrigerator system is connected to the outlet of the refrigerant pump. The gas-liquid separator is used to ensure that all the refrigerant entering the refrigerant pump exists in the form of liquid phase.

(8) The above-mentioned ice storage system includes an ice storage device and electromagnetic valves connected to both ends of the ice storage device.

(9) The above-mentioned ammonia vapor compression refrigeration cycle system includes a solenoid valve connected to the outlet of the multi-way valve, a compressor connected to the outlet of the solenoid valve, a condenser connected to the outlet of the compressor, a throttle valve and a check valve connected to the outlet of the condenser , Connect the check valve and solenoid valve of the gas-liquid separator gas outlet, and connect the cold storage system of the liquid-phase outlet of the gas-liquid separator, the gas-liquid separator is used to ensure that all the refrigerant entering the cold storage system exists in the form of liquid phase.

The beneficial effects of the present invention are:

The invention realizes the cascade utilization of LNG cold energy and improves the utilization rate of LNG cold energy; according to the optimized automatic control system, not only can the flow of the refrigerant be adjusted in real time to achieve the purpose of controlling the temperature of the cold storage, but also a variety of supply and demand can be realized. Simultaneous operation in the cooling mode solves the problem of the stability of the operation of the cold storage using LNG refrigeration; in the peak period of natural gas supply or when the electricity price is low, the cold storage system designed by the present invention can be used for cold storage, and in the low peak period or low electricity price of natural gas supply. When the electricity price is high, the stored cold energy is released, which reduces the operating cost of the system and ensures the continuous operation of the cold storage in extreme cases such as low LNG flow or power failure; the selected refrigerants R32 and liquid ammonia have high environmental impact. Friendliness; the use of refrigerant has phase change refrigeration, which can make full use of the latent heat of refrigerant vaporization for refrigeration and reduce the refrigerant flow;

Compared with the refrigeration process of the general cold storage, the invention greatly reduces the power consumption of the cold storage using the compressed vapor refrigeration cycle, and has high economic value. At the same time, the automatic control system can feedback the working conditions of the cold storage in real time, ensuring that the cold storage is efficient and effective. continuous operation in a sequential manner.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

1 is a schematic structural diagram of a high-adaptability cold storage multi-temperature cold storage system for cascade utilization of LNG cold energy according to the present invention;

Fig. 2 is the refrigerant pressure and enthalpy diagram under the ideal situation of the freezing-ultra-low temperature parallel cold storage system of the present invention;

In the figure, 1, 6, 20, 21, 28, 30, 63, 71, 78, 82 are three-way valves, 2, 4, 7, 10, 15, 17, 19, 25, 27, 29, 31, 36 , 37, 41, 45, 48, 49, 50, 52, 55, 56, 58, 64, 66, 68, 70, 72, 76, 79, 81, 83, 85, 86, 87, 88, 90 are electromagnetic Valves, 3, 11, 33, 43, 74 are thermal expansion valves, 5 is LNG-R32 heat exchanger, 12 is LNG-ammonia heat exchanger, 8, 46, 47, 77 are multi-port valves, 9 is LNG gas 13, 42, 51, 53, 54, 57, 62, 80, 89, 94 check valves, 14, 18, 40, 65, 69 are gas-liquid separators, 16, 26, 67 are refrigerant pumps, 22 is high pressure float valve, 23 is liquid level controller, 24 is R32 low temperature storage tank, 32, 38, 73 are temperature controllers, 34 is freezer, 35 is pressure regulating valve, 44 is ultra-low temperature storage, 59, 91 are Compressors, 60, 92 are condensers, 39, 61, 93 are throttle valves, 75 is a refrigerator, and 84 is an ice cold storage device.

Detailed ways

The specific embodiments of the present invention will be introduced below with reference to the accompanying drawings.

Referring to Fig. 1, the present invention is a high-adaptability multi-temperature cold storage system that can utilize LNG cold energy in cascade, which includes LNG gasification system, refrigeration-ultra-low temperature parallel cold storage system, and R32 circulating refrigeration system utilizing LNG cold energy, R32 cold storage system, R32 vapor compression refrigeration cycle system, cold storage system, ammonia cycle refrigeration system using LNG cold energy, ice cold storage system, ammonia vapor compression refrigeration cycle system.

(1) The above-mentioned LNG gasification system comprises a three-way valve 1, a solenoid valve 4 connected to the outlet of one end of the three-way valve 1, a solenoid valve 2 connected to the outlet of the other end of the three-way valve 1, and a solenoid valve 2 connected to the outlet of the solenoid valve 2. Thermal expansion valve 3, LNG-R32 heat exchanger 5 connected to the outlet of the thermal expansion valve 3, three-way valve 6 connected to the outlet of the LNG-R32 heat exchanger 5, and solenoid valve 7 connected to the outlet of one end of the three-way valve 6 , the electromagnetic valve 10 connected to the outlet of the other end of the three-way valve 6, the thermal expansion valve 11 connected to the outlet of the electromagnetic valve 10, the LNG-ammonia heat exchanger 12 connected to the outlet of the thermal expansion valve 11, and the LNG-ammonia heat exchanger 12 A check valve 13 connected to the outlet, a multi-way valve 8 connected to the outlet of the solenoid valve 4, the solenoid valve 7, and the check valve 13, and an LNG vaporizer connected to the outlet of the multi-way valve 8.

The solenoid valve 4 is used to control the on-off of the LNG direct gasification pipeline, the solenoid valve 2 is used to control the on-off of the LNG primary heat exchange pipeline, and the LNG-R32 heat exchanger 5 is used for In order to realize the heat exchange between the LNG pipeline and the R32 pipeline, the thermal expansion valve 3 is used to control the flow of LNG and then regulate the heat exchange between the LNG pipeline and the R32 pipeline, and the solenoid valve 7 is used to control the LNG pipeline. The on-off of the direct gasification pipeline after the primary heat exchange, the solenoid valve 10 is used to control the on-off of the LNG secondary heat exchange pipeline, and the LNG-ammonia heat exchanger 12 is used to realize the LNG pipeline For heat exchange with the ammonia pipeline, the thermal expansion valve 11 is used to control the flow of LNG and then regulate the amount of heat exchange between the LNG pipeline and the ammonia pipeline, the check valve 13 is used to prevent the backflow of the refrigerant, and the The LNG vaporizer 9 is used to completely vaporize the LNG for use by users.

(2) The above-mentioned freezing-ultra-low temperature parallel cold storage system includes a three-way valve 30, a solenoid valve 31 and a temperature controller 32 connected to the outlet of one end of the three-way valve 30, a thermal expansion valve 33 connected to the outlet of the solenoid valve 31, and a thermal expansion valve. The freezer 34 at the outlet of 33 is connected to the pressure regulating valve 35 of the outlet of the freezer 34, the solenoid valve 36 of the outlet of the pressure regulating valve 35 is connected, the solenoid valve 37 and the temperature controller 38 of the other end of the three-way valve 30 are connected, and the solenoid valve is connected The throttle valve 39 at the outlet of 37, the gas-liquid separator 40 connected to the outlet of the throttle valve 39, the solenoid valve 41 connected to the gas-phase outlet of the gas-liquid separator 40, the check valve 42 connected to the outlet of the solenoid valve 41, and the gas-liquid separator 40 The thermal expansion valve 43 of the liquid phase outlet, the ultra-low temperature storage 44 connected to the outlet of the thermal expansion valve 43, the electromagnetic valve 45 connected to the outlet of the ultra-low temperature storage 44, and the multi-port valve connected to the outlet of the electromagnetic valve 36, the check valve 42 and the electromagnetic valve 45 46.

The three-way valve 30 is used to realize that the low-temperature 32 refrigerant obtained by various refrigeration methods enters the freezing-ultra-low temperature parallel cold storage system, the solenoid valve 31 and the temperature sensor 32 are used to maintain the temperature of the freezer stable, and the thermal expansion The valve 33 is used to adjust the refrigerant flow, the freezer 34 is used to realize the utilization of LNG cold energy, the pressure regulating valve 35 is used to depressurize the refrigerant to mix with the low-pressure refrigerant at the outlet of the ultra-low temperature store, and the solenoid valve 36 is used for In order to control the on-off of the cryogenic storage refrigeration pipeline, the solenoid valve 37 and the temperature sensor 38 are used to maintain the temperature stability of the ultra-low temperature storage, and the throttle valve 39 is used to reduce the temperature and pressure of the refrigerant to meet the refrigeration temperature requirements of the ultra-low temperature storage. , the gas-liquid separator 40 is used to ensure that all the refrigerant entering the evaporator of the ultra-low temperature store 44 exists in the form of a liquid phase, the solenoid valve 41 is used to control the on-off of the gas-phase refrigerant pipeline, the check valve 42 is used to prevent the backflow of the refrigerant, the thermal expansion valve 43 is used to adjust the flow of refrigerant, the ultra-low temperature storage 44 is used to realize the utilization of LNG cold energy, and the electromagnetic valve 45 is used to control the refrigeration pipeline of the ultra-low temperature storage on and off.

(3) The above-mentioned R32 circulating refrigeration system utilizing LNG cold energy includes a solenoid valve 48 connected to the outlet of the multi-way valve 47, a LNG-R32 heat exchanger connected to the outlet of the solenoid valve 48, and a gas outlet connected to the LNG-R32 heat exchanger. The liquid separator 14, the solenoid valve 50 connected to the gas-phase outlet of the gas-liquid separator 14, the check valve 51 connected to the outlet of the solenoid valve 50, the solenoid valve 15 connected to the liquid-phase outlet of the gas-liquid separator 14, and the refrigerant at the outlet of the solenoid valve 15 Pump 16, the solenoid valve 17 connected to the outlet of the refrigerant pump 16, the three-way valves 20 and 21 connected to the outlet of the solenoid valve 17, the R32 cold storage system connected to the outlet of the three-way valve 21, and the solenoid valve 29 of the other end of the three-way valve 21 , connected to the refrigerated-ultra-low temperature parallel cold storage system at the outlet of solenoid valve 29.

The multi-port valve 47 is used to control the flow of gas-phase ammonia entering the ammonia vapor compression refrigeration system, the solenoid valves 48 and 49 are used to control the on-off of the heat exchange pipeline between R32 and LNG, and the LNG-R32 The heat exchanger 5 is used for the refrigerant to obtain LNG cold energy, the gas-liquid separator 14 is used to ensure that all the refrigerant entering the refrigerant pump exists in the form of liquid phase, and the solenoid valve 50 is used to control the passage of the gas-phase refrigerant pipeline. The check valve 51 is used to prevent the backflow of the refrigerant, the refrigerant pump 16 is used to provide power for the entire cycle, the solenoid valves 15 and 17 are used to control the opening and closing of the refrigerant pump 16, and the The three-way valve 20 is used for the confluence of the low-temperature refrigerant produced by the LNG cold energy refrigeration method and the vapor compression refrigeration method, and the three-way valve 21 is used to adjust the low-temperature refrigerant flow into the R32 cold storage system and the freezing-ultra-low temperature parallel cold storage system.

(4) The above-mentioned R32 cold storage system includes the R32 low-temperature storage tank 24, the high-pressure float valve 22 and the liquid level controller 23 connected to the liquid phase inlet of the R32 low-temperature storage tank 24, and the three-way valve 21 connected to the inlet of the high-pressure float valve 22. The check valve 54 at the gas phase inlet of the R32 cryogenic storage tank 24, the solenoid valve 55 at the outlet of the check valve 54, the solenoid valve 25 at the liquid phase outlet of the R32 cryogenic storage tank 24, the refrigerant pump 26 at the outlet of the solenoid valve 25, and the refrigerant The solenoid valve 27 at the outlet of the pump 26, the three-way valve 28 at the outlet of the solenoid valve 27, the freezer-ultra-low temperature parallel cold storage system at the outlet of the three-way valve 28, the solenoid valve 56 at the gas phase outlet of the R32 cryogenic storage tank 24, and the solenoid valve 56 Outlet check valve 57.

The R32 low-temperature storage tank is used to store a part of the R32 refrigerant that has been cooled to low temperature, the three-way valve 21 is used to adjust the refrigerant flow into the R32 cold storage system, and the high-pressure float valve 22 is used to control the R32 cold storage system. When the system pipeline is switched on and off, the liquid level controller 23 is used to monitor and adjust the storage volume of R32 in the low temperature storage tank in real time, so as to ensure that the storage volume of low temperature R32 does not exceed the warning line and store a sufficient amount of low temperature R32 to supply cooling when the cold storage cycle is turned on. The check valve 54 is used to prevent the backflow of the refrigerant, the solenoid valve 55 is used to control the on-off of the gas-phase R32 refrigerant returning to the R32 cold storage system pipeline, and the refrigerant pump 26 is used to store the R32 cold storage. The system provides power when supplying cooling to the cold storage system. The solenoid valves 25 and 27 are used to control the opening and closing of the refrigerant pump 26, and the solenoid valve 56 is used to control the on-off of the pipeline of the gas phase R32 entering the refrigerant cooling system. The aforementioned check valve 27 is used to prevent the backflow of the R32 refrigerant.

(5) The above-mentioned R32 vapor compression refrigeration cycle system includes the solenoid valve 58 connected to the outlet of the multi-way valve 47, the compressor 59 connected to the outlet of the solenoid valve 58, the condenser 60 connected to the outlet of the compressor 59, and the outlet of the condenser 60. The throttle valve 61 connected to the throttle valve 61, the check valve 62 connected to the outlet of the throttle valve 61, the gas-liquid separator 18 connected to the outlet of the check valve 62, the solenoid valve 52 connected to the gas-phase outlet of the gas-liquid separator 18, Check valve 53, the solenoid valve 19 connected to the liquid phase outlet of the gas-liquid separator 18, the three-way valves 20 and 21 connected to the outlet of the solenoid valve 19, the R32 cold storage system connected to the outlet of one end of the three-way valve 21, and the other side of the three-way valve 21. The solenoid valve 29 at one end of the outlet is connected to the freezer-ultra-low temperature parallel cold storage system at the outlet of the solenoid valve 29 .

The multi-port valve 47 is used to control the flow rate of the gas phase R32 entering the R32 vapor compression refrigeration system, the solenoid valves 58 and 19 are used to control the on-off of the R32 vapor compression refrigeration cycle pipeline, and the compressor 59 , condenser 60 and throttle valve 61 are used to realize the vapor compression refrigeration of R32 refrigerant, the check valve 62 is used to prevent the backflow of low-pressure R32 refrigerant, and the gas-liquid separator 18 is used to ensure that all the refrigerant entering the cold storage system is completely Existing in the form of liquid phase, the solenoid valve 52 is used to control the opening and closing of the gas phase refrigerant pipeline, and the check valve 53 is used to prevent the refrigerant from flowing back.

(6) The above-mentioned refrigerator system includes a solenoid valve 72 and a temperature controller 73 connected to the outlet of the three-way valve 71, a thermal expansion valve 74 connected to the outlet of the solenoid valve 72, a refrigerator 75 connected to the outlet of the thermal expansion valve 74, and a refrigerator The solenoid valve 76 at the outlet of the bank 75 is connected to the multi-port valve 77 at the outlet of the solenoid valve 76 .

The three-way valve 71 is used to realize that the low-temperature 32 refrigerant obtained by various refrigeration methods enters the refrigerator system, the solenoid valve 72 and the temperature sensor 73 are used to maintain the temperature of the refrigerator stable, and the thermal expansion valve 74 is used for In order to adjust the refrigerant flow, the refrigerator 75 is used to realize the utilization of LNG cold energy, the solenoid valve 76 is used to control the opening and closing of the pipeline of the refrigerator, and the multi-port valve 77 is used to realize the multi-phase gas phase. Confluence of R32 refrigerant.

(7) The above-mentioned ammonia cycle refrigeration system utilizing LNG cold energy includes a solenoid valve 79 connected to the outlet of the three-way valve 78, a three-way valve 83 connected to the outlet of the solenoid valve 79, and a solenoid valve 86 connected to the outlet of the three-way valve 82. The LNG-ammonia heat exchanger 12 at the outlet of the solenoid valve 86 is connected to the solenoid valve 87 at the outlet of the LNG-liquid ammonia heat exchanger 12, the three-way valve 63 at the outlet of the solenoid valve 87 is connected, and the solenoid valve 64 at the outlet of the three-way valve 63 is connected, The gas-liquid separator 65 is connected to the outlet of the solenoid valve 64, the solenoid valve 81 is connected to the gas-phase outlet of the gas-liquid separator 65, the check valve 80 is connected to the outlet of the solenoid valve 81, and the solenoid valve 66 is connected to the liquid-phase outlet of the gas-liquid separator 65, The refrigerant pump 67 is connected to the outlet of the solenoid valve 66, the solenoid valve 68 is connected to the outlet of the refrigerant pump 67, the three-way valves 71 and 72 are connected to the outlet of the solenoid valve 68, and the refrigerator system is connected to the outlet of the three-way valve 72.

The three-way valve 77 is used to control the flow of gas-phase ammonia entering the ammonia vapor compression refrigeration system. The LNG-ammonia heat exchanger 12 is used to exchange heat between liquid ammonia refrigerant and LNG to obtain LNG cold energy. The through valves 63, 82 and the solenoid valves 79, 86, 87, 64 are used to switch between the cold storage system utilizing LNG cold energy and the direct cooling system utilizing LNG cold energy, and the gas-liquid separator 65 is used for To ensure that all the refrigerant entering the refrigerant pump exists in the form of liquid phase, the solenoid valve 81 is used to control the opening and closing of the gas phase refrigerant pipeline, the check valve 80 is used to prevent the refrigerant from flowing back, and the refrigerant pump 67 is used for In order to provide power for the whole cycle, the solenoid valves 66 and 68 are used to control the opening and closing of the refrigerant pump 67, and the three-way valve 71 is used for the confluence of the low-temperature refrigerants obtained by the LNG cold energy refrigeration method and the vapor compression refrigeration method. Finally enter the cold storage system for cooling.

(8) The above-mentioned ice storage system includes an ice storage device 84 and solenoid valves 83 and 85 connected to both ends of the ice storage device.

The ice cold storage device 84 is used to store a part of the cold energy of LNG when the LNG supply is large, and the solenoid valves 83 and 85 are used to control the on-off of the pipeline of the ice cold storage device.

(9) The above-mentioned ammonia vapor compression refrigeration cycle system includes a solenoid valve 88 connected to the outlet of the three-way valve 78, a compressor 91 connected to the outlet of the solenoid valve 88, a condenser 92 connected to the outlet of the compressor 91, and an outlet of the condenser 92. Throttle valve 93 connected to the throttle valve 93 outlet, check valve 94 connected to the outlet of the check valve 94, gas-liquid separator 69 connected to the outlet of The check valve 89 is connected to the solenoid valve 70 of the liquid phase outlet of the gas-liquid separator 69 , the three-way valve 71 connected to the outlet of the solenoid valve 70 , and the refrigerator storage system connected to the outlet of the three-way valve 71 .

The three-way valve 77 is used to control the flow of gas-phase ammonia entering the ammonia vapor compression refrigeration system, the solenoid valves 88 and 70 are used to control the on-off of the ammonia vapor compression refrigeration cycle pipeline, and the compressor 91 , condenser 92 and throttle valve 93 are used to realize vapor compression refrigeration of ammonia refrigerant, described check valve 94 is used to prevent backflow of low-pressure ammonia refrigerant, and described solenoid valve 90 is used to control the on-off of gas phase refrigerant pipeline , the check valve 89 is used to prevent the backflow of the refrigerant, the gas-liquid separator 69 is used to ensure that the refrigerant entering the cold storage system is all in the liquid phase, and the three-way valve 71 is used for vapor compression refrigeration and The low-temperature refrigerant produced by the LNG cold energy refrigeration method finally enters the cold storage system for cooling.

Each process in the invention can adjust the change of flow through the optimized solenoid valve, thermal expansion valve, pressure regulating valve, and high-pressure float valve. The temperature controller is used to adjust the temperature of the cold storage to be constant at all times, and the liquid level controller is used to ensure the liquid level at all times. In a reasonable position, so as to achieve the purpose of automatic control.

Referring to Fig. 2, the pressure-enthalpy diagram of the refrigerant under ideal conditions of the refrigeration-ultra-low temperature parallel cold storage system of the present invention is composed of eight state points A, B, C, D, E, F, G, and H. The A point is the state point when the R32 refrigerant flows out from the multi-way valve 47, the B point is the state point after the R32 refrigerant is pressurized by the compressor 59, and the C point is the R32 refrigerant after being cooled by the condenser 60. The point D is the state point after the R32 refrigerant is cooled and depressurized by the throttle valve 61, the point H is the state point after the R32 refrigerant is cooled down by the LNG-R32 heat exchanger 5, and the point G The function is to indicate that there is a certain pressure drop during heat exchange between R32 and LNG and to make the process easier to understand. The E point is the state of the R32 refrigerant after passing through the freezer 34, and the A point is the state of the R32 refrigerant after passing through the pressure regulating valve 35. The point F is the state point after the R32 refrigerant passes through the throttle valve 39, and the point A is the state point after the R32 refrigerant passes through the ultra-low temperature storage. Figure 2 provides a theoretical basis for the realization of the system.

The specific working mode of the LNG cold energy cascade utilization system of the present invention is introduced as follows:

The pressure of the LNG coming out of the storage tank or tanker is about 0.6MPa, -160℃. The part of the LNG that is not directly vaporized by the solenoid valve 4 will be exchanged in the LNG-R32 heat exchanger and the LNG-liquid ammonia heat exchanger. The heat exchange temperature of the former refrigerant is -25--20 ℃, and the heat exchange temperature of the latter refrigerant is 0-5 ℃, and then the air temperature vaporizer 9 exchanges heat with the air and supplies it to the user.

Opening the solenoid valve 22 can open the R32 cold storage cycle, so that the R32 after heat exchange with the LNG flows into the R32 low-temperature storage tank 24 for storage, and is reserved as a backup refrigerant. During the period of use, the specific implementation is that the solenoid valves 25 and 27 are opened, and the R32 in the storage tank is pressurized by the refrigerant pump 26 and then enters the three-way valves 28 and 30 to start the refrigeration cycle of the cold storage. The sources of cold storage can be divided into two types. The first is that when the supply of LNG is large, the solenoid valve 49 can be opened to store the R32 cooled after heat exchange with LNG. The second is to open the electromagnetic valve at night when electricity prices are low. The valve 19 performs electro-compression refrigeration to store the low-temperature R32. When both conditions are satisfied, the two solenoid valves above can be opened to perform the cold storage work at the same time.

The temperature of R32 after heat exchange in the LNG-R32 heat exchanger is -30--25°C, and enters the gas-liquid separation tank 14 to separate the gas phase and the liquid phase R32, and the gas phase R32 passes through the solenoid valve 50 and the check valve 51. Then it enters the multi-way valve 46 and merges with the refrigerant R32 in the gas phase. The R32 in the liquid phase enters the three-way valve 20 after being pressurized by the refrigerant pump 16 from the liquid phase output end. One can enter the storage tank 24 for cold storage, and the other The stock can enter the cold storage refrigeration cycle through the solenoid valve 29. In the freezer refrigeration cycle, the refrigerant R32 first passes through the solenoid valve 31, and then passes through the thermal expansion valve 33 to adjust the flow, and then enters the evaporator of the freezer 34 for gasification and heat absorption. , the superheat degree of the thermal expansion valve is controlled according to the outlet temperature of the refrigerant at the output end of the freezer, and the refrigerant out of the evaporator passes through the pressure control valve 35 for pressure regulation and the solenoid valve 36 in turn, and then enters the multi-port valve 46. The refrigerant R32 in the gas phase converges to complete the subsequent cooling and liquefaction process; in the ultra-low temperature cold storage refrigeration cycle, the other refrigerant that is shunted first passes through the solenoid valve 37 and then passes through the throttle valve 39 to cool down. At this time, the temperature is -50—- 40 ℃, and then enter the gas-liquid separator 40 to separate the refrigerant in the gas phase and the liquid phase. The separated refrigerant in the gas phase passes through the solenoid valve 41 and the check valve 42 and then enters the multi-way valve 46 and merges with the refrigerant R32 in the gas phase. The separated liquid-phase refrigerant passes through the thermal expansion valve 43 to adjust the flow and enters the evaporator of the ultra-low temperature store 44 to carry out the gasification and heat absorption process. The refrigerant R32 converges to complete the subsequent cooling and liquefaction process.

In the LNG-ammonia heat exchanger, the ammonia after heat exchange passes through the solenoid valve 87 and then passes through the diversion effect of the three-way valve 63. On the one hand, it can enter the solenoid valve 85 and the subsequent ice storage device with internal power for cooling storage work, and on the other hand On the one hand, it can enter the gas-liquid separator 65 through the solenoid valve 64 to separate the ammonia in the liquid phase and the gas phase. After the ammonia is pressurized by the solenoid valve 66 and the refrigerant pump 67, it enters the evaporator of the refrigerator to vaporize and absorb heat. The vaporized refrigerant first passes through the solenoid valve 76, and then the refrigerant enters the multi-port valve 77 for confluence, and the confluent gas phase The refrigerant enters the LNG-ammonia heat exchanger together for cooling and liquefaction to complete the cycle. When the supply of liquefied natural gas is insufficient, the solenoid valve 86 can be closed first, so that the gas phase ammonia after passing through the cold storage passes through the solenoid valve 79 and the solenoid valve 83 in turn, enters the ice storage device 84 for heat exchange and liquefaction, and then supplies the cold storage for refrigeration to complete the cycle.

When the cold energy demand of the cold storage is large and the cold energy supplied by the LNG is insufficient, the cold storage system and the vapor compression refrigeration cycle system can be opened to meet the refrigeration demand, or the opening and closing of different cooling methods can be controlled according to the specific operating conditions of the system. To carry out any combination of various cooling methods, in order to improve the adaptability of the system to changes in load and LNG supply, and at the same time alleviate the high power load of electric compression refrigeration, improve operating efficiency, and bring considerable economic benefits.

Claims (8)

1. a kind of high adaptability cold storage multi-temperature cold storage system of cascade utilization of LNG cold energy, it is characterized in that comprising LNG gasification system, freezing-ultra-low temperature parallel cold storage system, utilizing the R32 circulating refrigeration system of LNG cold energy, R32 cold storage system, R32 Vapor compression refrigeration cycle system, refrigerator system, ammonia cycle refrigeration system using LNG cold energy, ice cold storage system, ammonia vapor compression refrigeration cycle system. The LNG gasification system includes a LNG-R32 heat exchanger, an LNG-ammonia heat exchanger, a thermal expansion valve, a solenoid valve, a check valve, a natural gas transportation pipeline network, and a refrigerant for the LNG-R32 heat exchanger. The input and output pipelines are connected to an R32 circulating refrigeration system utilizing LNG cold energy, and the refrigerant input and output pipelines of the LNG-liquid ammonia heat exchanger are connected to a liquid ammonia circulating refrigeration system utilizing LNG cold energy. The thermal expansion valve can adjust the LNG flow into the heat exchanger according to the set heat exchange temperature, the solenoid valve can adjust the LNG heat exchange mode according to the working mode of the cold storage, and the check valve can prevent the low-pressure pipeline refrigerant from flowing back. The freezing-ultra-low temperature parallel cold storage system includes a solenoid valve and a temperature controller connected to the outlet of the three-way valve, a thermal expansion valve connected to the outlet of the solenoid valve of the branch circuit of the freezer, a freezer connected to the outlet of the thermal expansion valve, and an outlet of the freezer. The pressure regulating valve, the multi-port valve connected to the outlet of the pressure regulating valve, the solenoid valve and the temperature controller connected to the outlet of the solenoid valve of the ultra-low temperature storehouse, the throttle valve connected to the outlet of the solenoid valve, the gas-liquid separator connected to the outlet of the throttle valve , connect the solenoid valve, check valve and multi-way valve of the gas-liquid separator gas outlet, connect the thermal expansion valve of the liquid-phase outlet of the gas-liquid separator, connect the ultra-low temperature warehouse of the thermal expansion valve outlet, and connect the check valve of the ultra-low temperature warehouse outlet , the multi-way valve connected to the outlet of the check valve, the gas-liquid separator is used to ensure that all the refrigerant entering the evaporator exists in the form of liquid phase, the solenoid valve and the temperature sensor are used to adjust the temperature of the cold storage to be stable, the thermal expansion valve It is used to adjust the flow of refrigerant, the throttle valve is used to cool the refrigerant, and the pressure regulating valve is used to reduce the pressure of the refrigerant. The R32 circulating refrigeration system utilizing LNG cold energy includes an LNG-R32 heat exchanger connected to the outlet of the multi-port valve, a gas-liquid separator connected to the outlet of the LNG-R32 heat exchanger, and an electromagnetic connected to the gas-phase outlet of the gas-liquid separator. Valve, check valve and multi-way valve, the refrigerant pump connected to the liquid phase outlet of the gas-liquid separator, and the refrigeration-ultra-low temperature parallel cold storage system connected to the outlet of the refrigerant pump, the LNG-R32 heat exchanger is used for the refrigerant to obtain LNG cold energy, so The gas-liquid separator is used to ensure that all the refrigerant entering the refrigerant pump exists in the form of liquid phase. The R32 cold storage system includes an R32 low temperature storage tank, a high pressure float valve and a liquid level controller connected to the liquid phase inlet of the R32 low temperature storage tank, a check valve and a solenoid valve connected to the gas phase inlet of the R32 low temperature storage tank, and a R32 low temperature storage tank. The refrigerant pump at the liquid phase outlet of the tank, the freezer-ultra-low temperature parallel cold storage system connected to the outlet of the refrigerant pump, and the solenoid valve and check valve connected to the gas phase outlet of the R32 cryogenic storage tank, the liquid level controller can monitor and adjust the cryogenic storage tank in real time The storage capacity of medium R32 ensures that it does not exceed the warning line and at the same time stores enough low temperature R32 to be used when the cold storage cycle is turned on for cooling. The R32 vapor compression refrigeration cycle system includes a solenoid valve connected to the multi-port valve, a compressor connected to the solenoid valve outlet, a condenser connected to the compressor outlet, a throttle valve and a check valve connected to the condenser outlet, and a gas connection. The check valve and solenoid valve of the gas phase outlet of the liquid separator are connected to the cold storage system of the liquid phase outlet of the gas-liquid separator. The gas-liquid separator is used to ensure that all the refrigerants entering the cold storage system exist in the form of liquid phase. The refrigerator system includes a solenoid valve and a temperature controller connected to the outlet of the three-way valve, a thermal expansion valve connected to the outlet of the solenoid valve, a refrigerator connected to the outlet of the thermal expansion valve, a solenoid valve and a multi-way valve connected to the outlet of the refrigerator , the solenoid valve and the temperature sensor are used to adjust the temperature stability of the cold storage, and the thermal expansion valve is used to adjust the refrigerant flow. The ammonia cycle refrigeration system utilizing LNG cold energy includes an LNG-ammonia heat exchanger connected to the outlet of the three-way valve, a gas-liquid separator connected to the outlet of the LNG-ammonia heat exchanger, and an electromagnetic separator connected to the gas-phase outlet of the gas-liquid separator. The check valve of the valve is connected to the refrigerant pump of the liquid phase outlet of the gas-liquid separator, and the refrigerator system connected to the outlet of the refrigerant pump. The gas-liquid separator is used to ensure that all the refrigerant entering the refrigerant pump exists in the liquid phase. The ice storage system includes an ice storage device and electromagnetic valves connected to both ends of the ice storage device. The ammonia vapor compression refrigeration cycle system includes a solenoid valve connected to the multi-port valve, a compressor connected to the solenoid valve outlet, a condenser connected to the compressor outlet, a throttle valve and a check valve connected to the condenser outlet, and a gas connection. The check valve and solenoid valve of the gas phase outlet of the liquid separator are connected to the cold storage system of the liquid phase outlet of the gas-liquid separator. The gas-liquid separator is used to ensure that all the refrigerants entering the cold storage system exist in the form of liquid phase. 2. A high-adaptability cold storage multi-temperature cold storage system for cascade utilization of LNG cold energy according to claim 1, characterized in that the cascade utilization of LNG cold energy is realized through the multi-temperature cold storage. 3. A kind of high-adaptability cold storage multi-temperature cold storage system with cascade utilization of LNG cold energy according to claim 1, it is characterized in that by adding R32 low temperature storage tank and ice cold storage device, the system is greatly improved to load change and LNG supply change adaptability. 4. A high-adaptability cold storage multi-temperature cold storage system with cascade utilization of LNG cold energy according to claim 1, is characterized in that, according to the actual operation situation of the cold storage, LNG cold energy refrigeration, vapor compression refrigeration, and cold storage device refrigeration can be The three cooling methods can be arbitrarily matched to meet the cooling needs at the minimum economic cost. 5. a kind of high-adaptability cold storage multi-temperature cold storage system of cascade utilization of LNG cold energy according to claim 1 is characterized in that adding a gas-liquid separator before entering the refrigerant pump or the evaporator of the cold storage, ensuring that the normal operation and high heat exchange efficiency of the evaporator. , 6. A high-adaptability cold storage multi-temperature cold storage system with cascade utilization of LNG cold energy according to claim 1, characterized in that the selected refrigerants are R32 and ammonia, which are highly friendly to the environment. 7 . The high-adaptability cold storage multi-temperature cold storage system according to claim 1 , characterized in that the use of R32 and ammonia has a phase-change refrigeration cycle, which reduces the flow of the refrigerant. 8 . 8. A kind of high-adaptability cold storage multi-temperature cold storage system of cascade utilization of LNG cold energy according to claim 1, is characterized in that the flow can be adjusted by preferred solenoid valve, thermal expansion valve, pressure regulating valve, high pressure float valve The temperature controller is used to adjust the temperature of the cold storage to be constant at all times, and the liquid level controller is used to ensure that the liquid level is always in a reasonable position, so as to achieve the purpose of automatic control.