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CN210089183U - Device for transferring LNG cold energy by using phase-change refrigerant - Google Patents

Device for transferring LNG cold energy by using phase-change refrigerant Download PDF

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Publication number
CN210089183U
CN210089183U CN201920471616.5U CN201920471616U CN210089183U CN 210089183 U CN210089183 U CN 210089183U CN 201920471616 U CN201920471616 U CN 201920471616U CN 210089183 U CN210089183 U CN 210089183U
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China
Prior art keywords
heat exchanger
valve
refrigerant
cold energy
lng cold
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Withdrawn - After Issue
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CN201920471616.5U
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Chinese (zh)
Inventor
徐文东
曾志伟
丁力
梁东
严万波
蔡振培
徐天宇
丁际昭
陈文龙
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Guangdong Zhongtong Lihua Energy Technology Co Ltd
Guangzhou Lolen Special Equipment Co Ltd
South China University of Technology SCUT
Original Assignee
Guangdong Zhongtong Lihua Energy Technology Co Ltd
Guangzhou Lolen Special Equipment Co Ltd
South China University of Technology SCUT
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Priority to CN201920471616.5U priority Critical patent/CN210089183U/en
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Abstract

The utility model discloses an utilize device of phase transition refrigerant transmission LNG cold energy, the device is including parallelly connected LNG cold energy transmission system, the PLC at former pipeline, LNG cold energy transmission system includes first heat exchanger, expansion valve, second heat exchanger, first governing valve, second governing valve, reheater, cross valve, compressor etc. first governing valve one end is connected the booster pump output of former pipeline, and the other end is connected a refrigerant interface of second heat exchanger, another refrigerant interface of second heat exchanger connects gradually second governing valve, reheater, pressure regulating counter input through the pipeline; two heat medium interfaces of the second heat exchanger are respectively connected with one interface of the four-way valve and the expansion valve, and the other three interfaces of the four-way valve are respectively connected with the input port and the output port of the first heat exchanger and the compressor. The utility model discloses simple easy implementation, heat exchange efficiency height, application scope advantage such as wide can use this technology to enlarge the scope that the LNG cold energy utilized.

Description

Device for transferring LNG cold energy by using phase-change refrigerant
Technical Field
The utility model relates to a natural gas cold energy field, concretely relates to utilize device of phase transition refrigerant transmission LNG cold energy.
Background
LNG (liquefied natural gas) is a high-efficiency clean energy source, is a main form of natural gas storage and transportation, has the density 625 times that of gaseous natural gas, and greatly reduces the storage and transportation cost of the natural gas. At present, large LNG receiving stations put into operation in China have 14 seats, and the demand of China for LNG can reach 4600 ten thousand tons in 2020 according to prediction. When the low-temperature LNG (-162 ℃) is gasified into normal-temperature gas, the cold energy of about 830MJ/t can be released, and the cold energy can be converted into electric energy of about 200 kW.h when the low-temperature LNG is used for power generation, so that the economic and energy-saving benefits of cold energy recycling are huge. The existing LNG cold energy recovery method mainly comprises cold energy power generation, air separation, liquid carbon dioxide and dry ice preparation, ice making, refrigeration in a refrigeration house and the like.
The phase change refrigerant is a refrigerant which generates a physical state change in the heat exchange and cooling process, the latent heat of the refrigerant in the phase change process is fully utilized, the cold absorption capacity is enhanced, and the usage amount of the refrigerant and the cost required by refrigerant circulation can be correspondingly reduced. The thermosiphon heat exchanger is a self-circulating heat exchanger, the gas entering the heat exchanger is liquefied due to cooling, so that the internal pressure of the heat exchanger is reduced, the gas at the inlet is continuously siphoned into the heat exchanger, and the gas can be continuously circulated without an additional delivery pump.
Chinese patents CN107940897A, CN107940893A and CN108005739A disclose three LNG cold energy cascade utilization methods, all of which propose to transfer the cold energy of LNG in three steps, first to perform liquefaction and separation of air or light hydrocarbon recovery or cold energy power generation by using the LNG cold energy, then to perform oil gas associated gas condensate recovery or prepare liquefied CO2 and dry ice or low-temperature crushed waste rubber, and finally to perform warehouse refrigeration or seawater desalination. The refrigerants in the circulation process need an additional pump to provide power, and a large amount of electric energy is consumed.
Chinese patent CN106288650A discloses a cold energy recovery process for normal temperature nitrogen, wherein LNG enters an LNG cold box in two ways, and one way enters a heat exchanger to exchange heat with normal temperature nitrogen, and the nitrogen is primarily cooled; and the other path of LNG enters a flash tank for flash evaporation, the LNG passing through the flash tank is divided into a gas phase and a liquid phase, and the liquid phase LNG is cooled to a cryogenic temperature to exchange heat with nitrogen so as to liquefy the nitrogen. Wherein, nitrogen with low boiling point is used as refrigerant, flash evaporation is carried out by using a flash tank, only partial nitrogen is liquefied, and the equipment cost is increased.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a to the problem in the LNG cold energy that above-mentioned proposed and present existing utilizes, provide a device and method that utilize phase transition refrigerant transmission LNG cold energy, when guaranteeing the normal liquefaction of one-level phase transition refrigerant, solved because of the freezing stifled that the supercooling of one-level phase transition refrigerant leads to, have that cold energy transmission system is simple easy to implement, heat exchange efficiency is high, application scope advantage such as wide, can use this technology to enlarge the scope that the LNG cold energy utilized.
The utility model discloses realize that the technical scheme of above-mentioned purpose does:
a device for transferring LNG cold energy by using phase-change refrigerant comprises an LNG cold energy transfer system and a PLC which are connected in parallel with an original pipeline,
parallelly connected LNG cold energy transfer system at former pipeline includes:
a first heat exchanger, an expansion valve, a second heat exchanger provided with a temperature and pressure transmitter, a first regulating valve, a second regulating valve, a reheater, a four-way valve, a compressor and a third regulating valve,
one end of the first regulating valve is connected with the output end of the booster pump of the original pipeline, the other end of the first regulating valve is connected with a refrigerant interface of the second heat exchanger, and the other refrigerant interface of the second heat exchanger is sequentially connected with the second regulating valve, the reheater and the input end of the pressure regulating meter of the original pipeline through pipelines; the two heat medium interfaces of the second heat exchanger are respectively connected with one interface of the four-way valve and the expansion valve, the other end of the expansion valve is connected with one refrigerant interface of the first heat exchanger, and the other three interfaces of the four-way valve are respectively connected with the other refrigerant interface of the first heat exchanger, the input port of the compressor and the input port of the compressor; the third regulating valve is connected between the first-stage phase change refrigerant and the input port of the compressor; two heat medium interfaces of the first heat exchanger are sequentially connected with a secondary refrigerant;
and the PLC is respectively in control connection with the expansion valve, the first regulating valve 4, the second regulating valve 5, the pressure regulating meter, the four-way valve, the third regulating valve and the temperature and pressure transmitter through circuits.
Further, the four-way valve is a three-position four-way reversing valve.
Furthermore, the second heat exchanger is a thermosiphon heat exchanger, so that the first-stage phase-change refrigerant can flow in spontaneously without an additional flow pump.
Furthermore, the first-stage phase-change refrigerant is gaseous before entering the second heat exchanger, and is partially liquefied after entering the second heat exchanger, so that the internal pressure of the second heat exchanger is reduced.
Further, the first-stage phase change refrigerant is CO2
Further, the secondary refrigerant is ethylene glycol.
Compared with the prior art and the current situation, the utility model has the following beneficial effects:
1. the energy is effectively utilized, and the resources are saved. The utility model replaces the original LNG cold energy utilization process, and recovers the wasted cold energy; the expanded and cooled low-temperature natural gas and the compressed first-stage phase-change refrigerant exchange heat in the thermosiphon heat exchanger, so that not only are the energy and equipment cost consumed for adjusting the temperature of the low-temperature natural gas saved in the original process, but also the cold quantity required by the refrigerant in use is saved;
2. the equipment is simple to operate and low in cost. The utility model discloses in utilizing compressor and cross valve can solve the thermosyphon heat exchanger simultaneously, gaseous state one-level phase transition refrigerant liquefaction inefficiency that leads to because of the pressure reduction and because of the stifled problem of freezing that leads to because of the one-level phase transition refrigerant temperature is too low, make the cold energy utilization efficiency of entire system improve, and easy operation, equipment low price;
3. the process flow is simple and easy to control, and the safety and stability are high. The utility model discloses mainly constitute by LNG cold energy transmission system, monitoring regulation and control system two parts, simple process, cold volume can carry out quick adjustment according to the user's demand, and entire system's work is whole to be accomplished by the control system control, and automatic strong adaptability. Furthermore, the utility model discloses a technology is parallelly connected with original pressure regulating station pressure regulating pipeline, and in case situation such as certain process units or equipment goes wrong takes place, autonomous system can be automatic with the medium switch to original process piping on, has ensured the security of system.
Drawings
Fig. 1 is a flow chart of a new process for transferring LNG cold energy by using a phase-change refrigerant.
In the figure: 1-a first heat exchanger; 2-an expansion valve; 3-a second heat exchanger; 4-a first regulating valve; 5-a second regulating valve; 6-pressure regulating meter; 7-a reheater; 8-PLC; a 9-four-way valve; 10-a compressor; 11-third regulating valve.
Detailed Description
For a better understanding of the present invention, the following description is given in conjunction with the accompanying drawings and examples, but the scope of the invention is not limited to the examples.
Taking a certain LNG receiving station as an example, the gasification station runs stably, and the natural gas 35000Nm3 is gasified for about 26875kg/h every hour and is gasified for 16 hours every day.
As shown in fig. 1, the device for transferring LNG cold energy by using phase-change refrigerant comprises an LNG cold energy transfer system connected in parallel to an original pipeline, a PLC8,
parallelly connected LNG cold energy transfer system at former pipeline includes:
a first heat exchanger 1, an expansion valve 2, a second heat exchanger 3 provided with a temperature and pressure transmitter, a first regulating valve 4, a second regulating valve 5, a reheater 7, a four-way valve 9, a compressor 10, a third regulating valve 11,
one end of the first regulating valve 4 is connected with the output end of a booster pump of an original pipeline, the other end of the first regulating valve is connected with a refrigerant interface of the second heat exchanger 3, and the other refrigerant interface of the second heat exchanger 3 is sequentially connected with a second regulating valve 5, a reheater 7 and the input end of a pressure regulating meter 6 of the original pipeline through pipelines; two heat medium interfaces of the second heat exchanger 3 are respectively connected with one interface of a four-way valve 9 and the expansion valve 2, the other end of the expansion valve 2 is connected with one refrigerant interface of the first heat exchanger 1, and the other three interfaces of the four-way valve 9 are respectively connected with the other refrigerant interface of the first heat exchanger 1, an input port of the compressor 10 and an input port of the compressor 10; the third regulating valve 11 is connected between the first-stage phase change refrigerant and the input port of the compressor 10; two heat medium interfaces of the first heat exchanger 1 are sequentially connected with a secondary refrigerant;
the PLC8 is respectively connected with the expansion valve 2, the first regulating valve 4, the second regulating valve 5, the pressure regulating meter 6, the four-way valve 9, the third regulating valve 11 and the temperature and pressure transmitter through circuits in a control way.
The four-way valve is a three-position four-way reversing valve.
The second heat exchanger is a thermosyphon heat exchanger, so that the first-stage phase-change refrigerant can flow in spontaneously without an additional flowing pump.
The first-stage phase-change refrigerant is gaseous before entering the second heat exchanger, and is partially liquefied after entering the second heat exchanger, so that the internal pressure of the second heat exchanger is reduced.
The first-stage phase change refrigerant is CO2And the secondary refrigerant is ethylene glycol.
In this embodiment, the LNG is pressurized to about 7MPa by the booster pump, the temperature is raised to about-130 ℃, and the LNG passes through the second heat exchanger 3 and the first-stage phase-change refrigerant CO2The heat exchange temperature is raised to about-30 ℃, and then the heat is reheated to an output temperature (about 5 ℃) by a reheater 7, and the output temperature and the natural gas gasified in the original gasifier group are subjected to micro-pressure regulation and metering by a pressure regulating meter 6 and then are conveyed to downstream users.
In this embodiment, the gaseous first-stage phase change refrigerant CO2After exchanging heat with LNG through the second heat exchanger 3, the liquid CO is cooled and liquefied2Liquid CO2The refrigerant is expanded and cooled by an expansion valve 2, enters a first heat exchanger 1 to exchange heat with a secondary refrigerant glycol, and then circulates according to the heat exchange. In the process, the first-stage phase change refrigerant CO2And transferring the cold energy in the LNG to a secondary refrigerant glycol.
Another embodiment of the present invention provides a method for transferring LNG cold energy by using phase-change refrigerant, wherein the method includes a first-stage phase-change refrigerant CO2Is controlled by the pressure and temperature in the second heat exchanger, comprising the steps of:
LNG flows out of the storage tank, enters the second heat exchanger 3, the second regulating valve 5 and the reheater 7 after passing through the booster pump and the first regulating valve 4, is subjected to pressure regulation and metering together with natural gas gasified in the original gasifier group, and is then conveyed to downstream users;
first-stage phase change refrigerant CO2Sequentially passes through a compressor 10, a four-way valve 9 and a secondThe second heat exchanger 3, the expansion valve 2 and the first heat exchanger 1 are circulated, and the first-stage phase change refrigerant CO is recycled in the process2Cold energy in LNG is transferred to a secondary refrigerant glycol of the first heat exchanger 1;
the PLC8 obtains the pressure and temperature in the second heat exchanger 3 through the temperature and pressure transmitter,
if the internal pressure of the second heat exchanger 3 is lower than 0.518MPa set by PLC8, the gaseous first-stage phase-change refrigerant CO2The flow is regulated by a third regulating valve 11, the gas is compressed into high-temperature and high-pressure gas by a compressor 10, the high-temperature and high-pressure gas enters a second heat exchanger 3 through a four-way valve 9, a connector A of the four-way valve 9 is communicated with a connector D and a connector B at the moment, namely the four-way valve is respectively communicated with the output end of the compressor 10, the second heat exchanger 3, the input end of the compressor 10 and the first heat exchanger 1, the internal pressure of the second heat exchanger 3 is increased, and gaseous one-stage phase change2Normal liquefaction of (2);
if the internal temperature of the second heat exchanger 3 is lower than-56.4 ℃ set by PLC8, the gaseous first-stage phase-change refrigerant CO2Is drawn out from the second heat exchanger 3 and enters the compressor 10 through the four-way valve 9, at the moment, the interface A of the four-way valve 9 is communicated with the interface B and the interface C is communicated with the interface D, namely, the four-way valve 9 is respectively communicated with the output end of the compressor 10, the first heat exchanger 1, the input end of the compressor 10 and the second heat exchanger 3, and the compressor 10 leads part of gaseous first-stage phase change refrigerant CO to2Feeding back CO2The pressure of the storage tank and the second heat exchanger 3 is reduced, so that the freezing and blocking of equipment and pipelines are prevented;
under normal working conditions, if the internal pressure and temperature of the second heat exchanger 3 are within the set values of the PLC8, the interface B of the four-way valve 9 is communicated with the interface D and the interface A is communicated with the interface C, namely, the four-way valve 9 is respectively communicated with the first heat exchanger 1 and the second heat exchanger 3, the output end and the input end of the compressor 10, and the first-stage phase change refrigerant CO is2The refrigerant flows out of the first heat exchanger 1 and directly enters the second heat exchanger 3 through the four-way valve 9, and the compressor 10 is suspended to reduce power consumption.
The utility model discloses utilize phase transition refrigerant transmission LNG cold energy, utilize thermosiphon heat exchanger to make LNG and phase transition refrigerant spontaneous circulation heat transfer, utilize compressor and cross valve to carry out pressure regulation to thermosiphon heat exchanger, solved that thermosiphon heat exchanger is inside to lead to getting phase transition refrigerant liquefaction inefficiency, to lead to getting to freeze stifled problem because of the phase transition refrigerant subcooling because of pressure reduction. The utility model has the advantages of the cold energy transmission system is simple easy to implement, heat exchange efficiency is high, application scope is wide, can use this technology to enlarge the scope that the LNG cold energy utilized.
The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (6)

1. A device for transferring LNG cold energy by using phase-change refrigerant is characterized by comprising an LNG cold energy transfer system and a PLC (8) which are connected in parallel with an original pipeline,
parallelly connected LNG cold energy transfer system at former pipeline includes:
a first heat exchanger (1), an expansion valve (2), a second heat exchanger (3) provided with a temperature-pressure transmitter, a first regulating valve (4), a second regulating valve (5), a reheater (7), a four-way valve (9), a compressor (10) and a third regulating valve (11),
one end of the first regulating valve (4) is connected with the output end of a booster pump of an original pipeline, the other end of the first regulating valve is connected with a refrigerant interface of the second heat exchanger (3), and the other refrigerant interface of the second heat exchanger (3) is sequentially connected with the input ends of a second regulating valve (5), a reheater (7) and a pressure regulating meter (6) of the original pipeline through pipelines; two heat medium interfaces of the second heat exchanger (3) are respectively connected with one interface of a four-way valve (9) and the expansion valve (2), the other end of the expansion valve (2) is connected with a refrigerant interface of the first heat exchanger (1), and the other three interfaces of the four-way valve (9) are respectively connected with the other refrigerant interface of the first heat exchanger (1), an input port of the compressor (10) and an output port of the compressor (10); the third regulating valve (11) is connected between the first-stage phase change refrigerant and the input port of the compressor (10); two heat medium interfaces of the first heat exchanger (1) are sequentially connected with a secondary refrigerant;
PLC (8) through the circuit respectively with expansion valve (2), first governing valve (4), second governing valve (5), pressure regulating counter (6), cross valve (9), third governing valve (11), warm-pressing changer control connection.
2. The device for transferring LNG cold energy by using the phase-change refrigerant as claimed in claim 1, wherein the four-way valve (9) is a three-position four-way reversing valve.
3. The apparatus for transferring cold energy of LNG as claimed in claim 1, wherein the second heat exchanger (3) is a thermosiphon heat exchanger.
4. The device for transferring the LNG cold energy by using the phase-change refrigerant according to claim 1, wherein the primary phase-change refrigerant is in a gaseous state before entering the second heat exchanger (3), and is partially liquefied after entering the second heat exchanger (3), so that the internal pressure of the second heat exchanger (3) is reduced.
5. The apparatus of claim 1, wherein the primary phase-change refrigerant is CO2
6. The apparatus of claim 1, wherein the secondary refrigerant is ethylene glycol.
CN201920471616.5U 2019-04-09 2019-04-09 Device for transferring LNG cold energy by using phase-change refrigerant Withdrawn - After Issue CN210089183U (en)

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Application Number Priority Date Filing Date Title
CN201920471616.5U CN210089183U (en) 2019-04-09 2019-04-09 Device for transferring LNG cold energy by using phase-change refrigerant

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109974339A (en) * 2019-04-09 2019-07-05 华南理工大学 A kind of device and method using phase transformation coolant transmission LNG cold energy

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109974339A (en) * 2019-04-09 2019-07-05 华南理工大学 A kind of device and method using phase transformation coolant transmission LNG cold energy
CN109974339B (en) * 2019-04-09 2023-08-11 华南理工大学 Device and method for transferring LNG cold energy by using phase-change refrigerant

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