WO2019032050A1 - Method and system for cold energy recovery - Google Patents

Method and system for cold energy recovery Download PDF

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Publication number
WO2019032050A1
WO2019032050A1 PCT/SG2018/050403 SG2018050403W WO2019032050A1 WO 2019032050 A1 WO2019032050 A1 WO 2019032050A1 SG 2018050403 W SG2018050403 W SG 2018050403W WO 2019032050 A1 WO2019032050 A1 WO 2019032050A1
Authority
WO
WIPO (PCT)
Prior art keywords
cold energy
cooling medium
heat exchanger
cooling
water
Prior art date
Application number
PCT/SG2018/050403
Other languages
French (fr)
Inventor
Yang Kwang FOO
Song Hau LIM
Original Assignee
Sp Innovation Pte. Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sp Innovation Pte. Ltd. filed Critical Sp Innovation Pte. Ltd.
Priority to SG11202000582QA priority Critical patent/SG11202000582QA/en
Publication of WO2019032050A1 publication Critical patent/WO2019032050A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F5/00—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater
    • F24F5/0007—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning
    • F24F2005/0039—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning using a cryogen, e.g. CO2 liquid or N2 liquid

Definitions

  • the invention relates to a system and method for reducing the temperature of a cooling medium.
  • the invention relates to the recovery of cold energy from a first source for application to a cooling medium for a district cooling systems (DCS).
  • DCS district cooling systems
  • District cooling refers to the centralized production of chilled water which is subsequently delivered to end users as a source of cold energy for the purposes of air- conditioning etc.
  • the energy savings resulting from district cooling can be considerable as compared to those of conventional air-conditioning systems and hence the progressively wider application of the technology for large scale use.
  • the invention provides a method for transferring cold energy for a district cooling system, comprising the steps of: releasing cold energy to a cooling medium, and consequently chilling said cooling medium; transporting the chilled cooling medium to a district cooling system; transferring said cold energy to the district cooling system.
  • the invention provides a system for transferring cold energy to a district cooling system, comprising: a cold energy transfer device for receiving cold energy from a cold energy source; said cold energy transfer device in heat transfer communication with a pipeline system, said pipeline system is arranged to circulate a cooling medium from the cold energy transfer device to a first heat exchanger; said first heat exchanger in heat transfer communication with a district cooling system, said first heat exchanger arranged to transfer cold energy from the cooling medium to water circulating within the district cooling system.
  • cold energy may be transferred to a heat transfer media and subsequently use in the district cooling system.
  • LNG liquid natural gas
  • NG natural gas
  • the cold energy removed from the LNG may be transferred to a heat transfer media which in turn transports and transfers the cold energy via heat exchangers to chill the chilled water of the DCS.
  • the cooling medium in this embodiment, may include potable water, seawater, or encapsulated water.
  • Figure 1 is a schematic view of a district cooling system according to one embodiment of the present invention.
  • the cold energy can be used to chill the return chilled water (within the district cooling distribution circuit) and also to lower the cooling tower water temperature (within the cooling tower water circuit).
  • the energy saving in the district cooling distribution circuit can be substantial as it means doing away with the electrical energy input to the compressor (DCS typically uses vapour compression technology).
  • DCS typically uses vapour compression technology
  • there is a spill over energy saving because the entire cooling tower water circuit temperature will be lowered. It is estimated that for every degree lower in cooling tower water temperature, the energy saving for the compressor is about 3%.
  • the cold energy recovered from gasification of liquid natural gas there will be energy saving for the DCS in both the district cooling distribution circuit and cooling tower water circuit.
  • the chillers for the cooling system may be proximate to facilities arranged to remove cold energy from the liquid natural gas.
  • Such facilities may include an encapsulation plant such as an open rack vapourisers (ORV) using sea water as a heat transfer medium.
  • ORV open rack vapourisers
  • the sea water enters the encapsulation plant at a temperature of 25°C.
  • the sea water return temperature to the sea should not be lower than 20°C. With a known volume of LNG to be converted, and the limit on return temperature, the required volume of sea water can then be calculated.
  • liquid natural gas facilities may be some distance from the district cooling system and therefore a heat transfer media to transport the cold energy may be required.
  • FIG. 1 shows one embodiment of the present invention.
  • a supply of water undergoes cold encapsulation 1 , providing a supply of chilled encapsulated water 5 to the system.
  • the encapsulated water may be sourced from a reclamation plant, which is brought into heat transfer communication a cold energy transfer device, such as an open rack vapourizer.
  • the encapsulation plant is arranged to impart the cold energy from the gasification process to the encapsulated water, producing a flow of chilled encapsulated water.
  • the temperature reduced as a result of the gasification of a cryogenic fluid, for instance, converting LNG to NG, with the resulting cold energy being sufficient to reduce the temperature of the encapsulated water from 25°C to 3°C.
  • the extracted cold energy is then transported 10 to the DCS via a pipeline system arranged to circulate the now chilled encapsulated water.
  • the advantages include a reduction capital expenditure as a result of fewer chillers, pumps and cooling towers.
  • the present invention allows the use of the infrastructure as compared to prior art systems that require a dual pipe system, and the associated capital expenditure.
  • the single pipe according to the present invention therefore, not only represents an efficient delivering cold energy, but also the dual use of the cooling medium where existing infrastructure requires only slight modification to produce a high yield result.
  • the resultant water 40 from the first group of heat exchanges 15 is then sent to the second group of heat exchangers 50 which exchanges heat with a cooling tower water circuit.
  • the cooling tower water circuit includes a cooling tower loop 95 will translate to further energy savings.
  • the cooling medium enters the first heat exchanger 15 to lower the temperature of the chilled water in the district cooling distribution circuit, where the cooling medium is heated from approx. 3°C to 12°C.
  • the cooling medium that leaves 40 the first heat exchanger 15 then enters the second heat exchanger 50 to transfer residual cold energy, so as to lower the cooling tower water temperature of the cooling tower water circuit, where the cooling medium is heated to approx. 12°C to 25°C.
  • the cooling medium that leaves 45 the second heat exchanger 50 returns 55 to the source in substantially the same temperature (approx. 25°C) as before the first step when the cooling medium is cooled from 25°C to 3°C
  • the chilled water 20 for the DCS is then directed to the various end users 25 at a temperature corresponding the latent heat load, for instance, at 5°C.
  • the DCS may include intermediate chillers 60, 65 receiving return water 57, 67 from the end users, as with conventional DCS system.
  • the DCS return water is then directed back to the first heat exchangers 15.
  • the cooling tower water circuit typically includes cooling tower loop 95, having inflow and outflow atmospheric air 105, 1 10 and providing cooling water 1 15. 120. This may act to provide heated water 75, 80 to the intermediate chillers 65 and the second heat exchangers 50. The interaiediate chillers 60 may also receive water 70 from the second heat exchangers 50.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Other Air-Conditioning Systems (AREA)

Abstract

A method for transferring cold energy for a district cooling system, comprising 5 the steps of: releasing cold energy to a cooling medium, and consequently chilling said cooling medium; transporting the chilled cooling medium to a district cooling system; transferring said cold energy to the district cooling system.

Description

METHOD AND SYSTEM FOR COLD ENERGY RECOVERY
Field of the Invention The invention relates to a system and method for reducing the temperature of a cooling medium. In particular, the invention relates to the recovery of cold energy from a first source for application to a cooling medium for a district cooling systems (DCS).
Background
District cooling refers to the centralized production of chilled water which is subsequently delivered to end users as a source of cold energy for the purposes of air- conditioning etc. The energy savings resulting from district cooling can be considerable as compared to those of conventional air-conditioning systems and hence the progressively wider application of the technology for large scale use.
Given the large capital expenditure involved with district cooling, decreasing the breakeven period, through further reducing operational cost, is therefore a highly sort after goal. Opportunities to reduce operational cost may be available at various strategies within the system, but a particularly important strategy includes reducing the energy cost associated with cooling the chilled water of the DCS.
Summary of Invention In a first aspect, the invention provides a method for transferring cold energy for a district cooling system, comprising the steps of: releasing cold energy to a cooling medium, and consequently chilling said cooling medium; transporting the chilled cooling medium to a district cooling system; transferring said cold energy to the district cooling system. In a second aspect, the invention provides a system for transferring cold energy to a district cooling system, comprising: a cold energy transfer device for receiving cold energy from a cold energy source; said cold energy transfer device in heat transfer communication with a pipeline system, said pipeline system is arranged to circulate a cooling medium from the cold energy transfer device to a first heat exchanger; said first heat exchanger in heat transfer communication with a district cooling system, said first heat exchanger arranged to transfer cold energy from the cooling medium to water circulating within the district cooling system.
Thus, by using the cold energy made available through a separate process, for instance, gasifying a cryogenic fluid such as liquid natural gas (LNG) to natural gas (NG), cold energy may be transferred to a heat transfer media and subsequently use in the district cooling system. This has the advantage of reducing the energy consumed by chillers and cooling towers and, in some circumstances, may save on initial capital expenditure through removing the requirement for such infrastructure.
In one embodiment, the cold energy removed from the LNG may be transferred to a heat transfer media which in turn transports and transfers the cold energy via heat exchangers to chill the chilled water of the DCS.
The cooling medium, in this embodiment, may include potable water, seawater, or encapsulated water. Brief Description of Drawings
It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.
Figure 1 is a schematic view of a district cooling system according to one embodiment of the present invention.
Detailed Description
With a considerable proportion of the energy expended to reduce the temperature of returned chilled water within the DCS, opportunities for reducing the required energy output will have a significant effect on the economics of the DCS.
For instance, by introducing cold energy from unrelated processes to chill the water within the DCS may reduce the energy requirements for chiller to produce the chilled water and, if of sufficient volume, possibly replace chillers and cooling towers traditionally used to produce chilled water.
One source of cold energy is in the waste cold energy dissipated during the conversion of liquid natural gas to natural gas. The cold energy can be used to chill the return chilled water (within the district cooling distribution circuit) and also to lower the cooling tower water temperature (within the cooling tower water circuit). The energy saving in the district cooling distribution circuit can be substantial as it means doing away with the electrical energy input to the compressor (DCS typically uses vapour compression technology). In addition, there is a spill over energy saving because the entire cooling tower water circuit temperature will be lowered. It is estimated that for every degree lower in cooling tower water temperature, the energy saving for the compressor is about 3%. Thus, for the cold energy recovered from gasification of liquid natural gas there will be energy saving for the DCS in both the district cooling distribution circuit and cooling tower water circuit.
In one embodiment the chillers for the cooling system may be proximate to facilities arranged to remove cold energy from the liquid natural gas. Such facilities, traditionally, may include an encapsulation plant such as an open rack vapourisers (ORV) using sea water as a heat transfer medium. The sea water enters the encapsulation plant at a temperature of 25°C. In order to minimise the environmental impact of returning lower temperature sea water to the sea, the sea water return temperature to the sea should not be lower than 20°C. With a known volume of LNG to be converted, and the limit on return temperature, the required volume of sea water can then be calculated.
If the DCS is sufficiently close to the encapsulation plants then using water as heat transfer medium between the encapsulation plant and the DCS, there is no need for the use of sea water as heat transfer medium, removing the need for sea water.
Alternatively, the liquid natural gas facilities may be some distance from the district cooling system and therefore a heat transfer media to transport the cold energy may be required.
Figure 1 shows one embodiment of the present invention. A supply of water undergoes cold encapsulation 1 , providing a supply of chilled encapsulated water 5 to the system. The encapsulated water may be sourced from a reclamation plant, which is brought into heat transfer communication a cold energy transfer device, such as an open rack vapourizer. The encapsulation plant is arranged to impart the cold energy from the gasification process to the encapsulated water, producing a flow of chilled encapsulated water. The temperature reduced as a result of the gasification of a cryogenic fluid, for instance, converting LNG to NG, with the resulting cold energy being sufficient to reduce the temperature of the encapsulated water from 25°C to 3°C.
The extracted cold energy is then transported 10 to the DCS via a pipeline system arranged to circulate the now chilled encapsulated water. This permits the pipeline system to consist of a single pipe to the DCS plant and subsequently into the first group of heat exchangers 15 to chill the return chilled water of the DCS. The advantages include a reduction capital expenditure as a result of fewer chillers, pumps and cooling towers. In particular, for instances where the single pipe is already in existence for a separate purpose, such as to circulate a fluid that may be used for the cooling medium, the present invention allows the use of the infrastructure as compared to prior art systems that require a dual pipe system, and the associated capital expenditure. The single pipe according to the present invention therefore, not only represents an efficient delivering cold energy, but also the dual use of the cooling medium where existing infrastructure requires only slight modification to produce a high yield result.
The resultant water 40 from the first group of heat exchanges 15 is then sent to the second group of heat exchangers 50 which exchanges heat with a cooling tower water circuit. The cooling tower water circuit includes a cooling tower loop 95 will translate to further energy savings. The cooling medium enters the first heat exchanger 15 to lower the temperature of the chilled water in the district cooling distribution circuit, where the cooling medium is heated from approx. 3°C to 12°C.
The cooling medium that leaves 40 the first heat exchanger 15 then enters the second heat exchanger 50 to transfer residual cold energy, so as to lower the cooling tower water temperature of the cooling tower water circuit, where the cooling medium is heated to approx. 12°C to 25°C. The cooling medium that leaves 45 the second heat exchanger 50 returns 55 to the source in substantially the same temperature (approx. 25°C) as before the first step when the cooling medium is cooled from 25°C to 3°C
The chilled water 20 for the DCS is then directed to the various end users 25 at a temperature corresponding the latent heat load, for instance, at 5°C. The DCS may include intermediate chillers 60, 65 receiving return water 57, 67 from the end users, as with conventional DCS system. The DCS return water is then directed back to the first heat exchangers 15.
The cooling tower water circuit typically includes cooling tower loop 95, having inflow and outflow atmospheric air 105, 1 10 and providing cooling water 1 15. 120. This may act to provide heated water 75, 80 to the intermediate chillers 65 and the second heat exchangers 50. The interaiediate chillers 60 may also receive water 70 from the second heat exchangers 50.

Claims

1. A method for transferring cold energy for a district cooling system, comprising the steps of: releasing cold energy to a cooling medium, and consequently chilling said cooling medium; transporting the chilled cooling medium to a district cooling system; transferring said cold energy to the district cooling system.
The method according to claim 1, wherein the releasing step includes applying the cooling medium to a cryogenic fluid so as to gasify said cryogenic fluid, chilling said cooling medium.
The method according to any one of the preceding claims, wherein the transferring step includes introducing the chilled cooling medium to a heat exchanger in heat transfer communication with the district cooling system, and passing a flow of return water from the district cooling system, and then releasing the cold energy from the chilled cooling medium to the return water flow.
The method according to claim 3, wherein the transferring step further includes directing the cooling medium from the heat exchanger to a second heat exchanger, said second heat exchanger in heat transfer communication with a cooling tower water circuit, and extracting residual cold energy from the cooling medium.
The method according to claim 4, further including the step of exiting the second heat exchanger, such that the temperature of the cooling medium is substantially the same as the temperature before the cold energy releasing step.
6. The method according to any one of the preceding claims, wherein the cryogenic fluid includes LNG.
The method according to any one of the preceding claims, wherein the cooling medium includes any one or a combination of potable water, encapsulated water and sea water.
8. A system for transferring cold energy to a district cooling system, comprising: a cold energy transfer device for receiving cold energy from a cold energy source; said cold energy transfer device in heat transfer communication with a pipeline system, said pipeline system is arranged to circulate a cooling medium from the cold energy transfer device to a first heat exchanger; said first heat exchanger in heat transfer communication with a district cooling system, said first heat exchanger arranged to transfer cold energy from the cooling medium to water circulating within the district cooling system.
9. The system according to claim 8, wherein the pipeline system consists of a
single pipe.
10. The system according to claim 8 or 9, wherein the cold energy transfer device is arranged to receive cold energy from a system for the gasification of a cryogenic fluid.
1 1. The system according to any one of claims 8 to 10, wherein the pipeline system is further arranged to circulate the cooling medium to a second heat exchanger, said second heat exchanger downstream from the first heat exchanger.
12. The system according to any one of claims 8 to 1 1, wherein the pipeline is
arranged to circulate the cooling medium from the second heat exchanger back to a cooling medium source.
13. The system according to any one of claims 8 to 12, wherein the cryogenic fluid includes LNG.
14. The system according to any one of claims 8 to 13, wherein the cooling medium includes any one or a combination of potable water, encapsulated water and sea water.
PCT/SG2018/050403 2017-08-07 2018-08-07 Method and system for cold energy recovery WO2019032050A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
SG11202000582QA SG11202000582QA (en) 2017-08-07 2018-08-07 Method and system for cold energy recovery

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SG10201706434U 2017-08-07
SG10201706434U 2017-08-07

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1342879A (en) * 2000-09-13 2002-04-03 谢红飞 Method for utilizing cold on gasifying liquefied natural gas
CN102589227A (en) * 2012-03-16 2012-07-18 华南理工大学 Method and device for cooling air-conditioning circulating water by using cold energy of liquefied natural gas
CN102213504B (en) * 2011-04-18 2012-11-14 四川空分设备(集团)有限责任公司 System for using LNG (Liquefied Natural Gas) in air conditioner
CN103363606A (en) * 2013-07-15 2013-10-23 深圳市燃气集团股份有限公司 Multi-cold-source ice storage air conditioning system with liquid level balance mechanism
CN203533757U (en) * 2013-10-15 2014-04-09 中国石油大学(华东) Low-temperature natural gas refrigerating capacity recycling and refrigerating system
CN105066512A (en) * 2015-09-14 2015-11-18 西南石油大学 LNG satellite station cooling heat and power cogeneration technology
CN105258258A (en) * 2015-09-17 2016-01-20 张守庆 Data center air conditioning system based on liquefied natural gas (LNG) cold energy application and application method thereof
CN205014038U (en) * 2015-08-13 2016-02-03 中节能（常州）城市节能研究院有限公司 LNG gasification cold energy is retrieved and traditional cooling cooling tower combination system
CN106288082A (en) * 2016-08-23 2017-01-04 庹华明 A kind of industry liquid nitrogen cold recovery system

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1342879A (en) * 2000-09-13 2002-04-03 谢红飞 Method for utilizing cold on gasifying liquefied natural gas
CN102213504B (en) * 2011-04-18 2012-11-14 四川空分设备(集团)有限责任公司 System for using LNG (Liquefied Natural Gas) in air conditioner
CN102589227A (en) * 2012-03-16 2012-07-18 华南理工大学 Method and device for cooling air-conditioning circulating water by using cold energy of liquefied natural gas
CN103363606A (en) * 2013-07-15 2013-10-23 深圳市燃气集团股份有限公司 Multi-cold-source ice storage air conditioning system with liquid level balance mechanism
CN203533757U (en) * 2013-10-15 2014-04-09 中国石油大学(华东) Low-temperature natural gas refrigerating capacity recycling and refrigerating system
CN205014038U (en) * 2015-08-13 2016-02-03 中节能（常州）城市节能研究院有限公司 LNG gasification cold energy is retrieved and traditional cooling cooling tower combination system
CN105066512A (en) * 2015-09-14 2015-11-18 西南石油大学 LNG satellite station cooling heat and power cogeneration technology
CN105258258A (en) * 2015-09-17 2016-01-20 张守庆 Data center air conditioning system based on liquefied natural gas (LNG) cold energy application and application method thereof
CN106288082A (en) * 2016-08-23 2017-01-04 庹华明 A kind of industry liquid nitrogen cold recovery system

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