Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/02—Treatment of water, waste water, or sewage by heating
  • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
  • C02F1/16—Treatment of water, waste water, or sewage by heating by distillation or evaporation using waste heat from other processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/007—Energy recuperation; Heat pumps
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
  • Y02A20/124—Water desalination
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
  • Y02B30/52—Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency

Definitions

• the present invention relates to a method and means for reducing the need .for energy supplied to distillation processes, especially in the desalination of salt water.
• Desalination of sea water may be accomplished in many different ways. In the most commonly used processes- the water is heated to evaporation, whereupon the salt-free water vapor is made to condens and the condensate, which consists of fresh water, is then collected in a convenient manner separate from the salty residual liquid in the distillation vessel.
• the energy used is between 120 and 50 kcal/kg of distillate (i.e. 240 - 100 times the theoretical minimum)
• plants of the vapor compression type which are used only to a limited extent in smaller units, it is possible to get down to about 15 kcal/kg of distillate i.e. about 30 times the theoretical minimum. This is largely due to the fact that both the end products and c the residues leave the plant with a surplus temperature.
• the invention has for its object to provide a method of reducing the need for energy supplied to distillation processes, especially in the desalination of salt water, whereby the energy requirement may by considerably reduced while maintaining the production capacity.
• the invention also comprises means for performing the method according to the inventio.n and of a kind comprising at least
• Figure 1 shows, in diagrammatic form, an embodiment of a device for the distillation of liquids, for instace for the desalination of sea water, and this device comprises at least one.
• column to which raw water to be distilled is fed at 1.
• the raw water is passed in a conduit through a condensor two disposed in the upper portion of the column and will there take up heat energy in connection with condensation.
• the column also comprises an evaporator 3 to which the preheated raw water is sprayed.
• evaporator 3 which is preferably disposed below the condensor 2 there will preferably be a sufficient low pressure for the raw water sprayed into the evaporator to boil, whereat the heat supplied by the preheating in the condensor 2 will be utilized for the evaporation, while at the same time the low temperature will reduce the risk of fur deposits.
• the vapor thus formed in evaporator 3 will condensate in the condensor 2, and the condensate will leave the column through a condensate outlet 4.
• the raw liquid which thus has been supplied with condensation heat in the condensor 2 is transported from the condensor to the evaporator 3 by the intermediary of a heat exchanger 5 constituting the condensor of a heat pump system which forms a closed system separate from the distillation system and which also comprises an apparatus part 6 with compressor and valve and a second heat exchanger 7, which serves as the evaporator of the heat pump.
• the heat pump 5, 6, 7 may also take up heat from a third heat exchanger 8, an evaporator which takes up heat from some heat source (not shown) which is accesi in the vicinity and suitable from economical point of view, for instance solar heat, heat from surface sea water of a comparatively high temperature, cooling water etc.
• the raw water may be supplied with further heat energy from the heat generated by the heat pump and its driving means e.g. cooling water and exhaust gases from a diesel engine which drives the heat pump (in the drawings symbolised by the conduit 10 and the heat exchange/condensor 9) .
• driving means e.g. cooling water and exhaust gases from a diesel engine which drives the heat pump (in the drawings symbolised by the conduit 10 and the heat exchange/condensor 9) .
• the condensate from the product outlet 4 is passed via a conduit 11 through the heat exchanger/evaporator 7 and, furthermore the recidual liquid is passed through a conduit 12 which likewise passes through the heat exchanger/evaporator 7.
• the condensate and the recidual liquid will leave the heat exchanger with substantially the same temperature after giving of heat energy in the heat exchanger/evaporator 7.
• a condition pertaining to the plant in its entirety should be that the temperatures of the product condensate and the residual liquid behind the evaporator 7 of the heat pump should be approximatly equal to, or even lower than, the temperature of the incoming raw liquid 1.
• the column is prodived with a gas collecting chamber 13, intended to collect gases disolved in the raw liquid which do not condensate on the condensor 2 but have to be collected and pumped out by the aid of an evacuation pump 14.
• the pump 14 will maintain a sub-atmospheric pressure suitable for the process.
• the pump 14 may also increase the efficiency of the plant if it handles a larger quantity of gas than the minimum of what is needed for removing gases disolved in the water, whereby the through-flow will increase through the condensor zone 2.
• the pump 14 will thereby transport water vapor to a further heat exchanger/condensor 15 where the energy will be transferred to the raw water which thereafter will proceed to the evaporator 3. (In this case the pump 14 will also serve as a heat pump) . If the liquid condensed in the heat exchanger/condensor 15 is sufficiently clean, it will be supplied after the separation and removal of non-condensing gases, to the product water and removed through the product conduit 11.
• a low pressure pump 16 with a pump motor 17, said pump being provided for the purpose of considerably increasing the rate of evaporation and condensation and thereby increasing the amount of product water per hour if necessary.
• the pump is of a well known type with a large volume capacity at a low pressure differential.
• FIG. 2 is a diagram of a modified embodiment of a device according to the invention.
• this device comprises at least one column with a raw water inlet 21 which passes in to and through a condensor 22 in the upper portion of the column.
• the raw water thus heated by condensation taking place in the condensor is thereafter conducted to a spray ramp 23a through which the raw water is sprayed out into an evaporator provided in the lower portion of the column.
• a sub-atmospheric pressure is maintained in this evaporator which will cause the raw liquid sprayed into the evaporator to be evaporated, whereat the vapor will flow upwardly and will be at least partly condensated as product water in the condensor 22 from which the water is removed from the column through a product water outlet 24.
• a first heat exchanger 25 which serves as the condensor in a heatpump system comprising a heatpump 26 with a valve and a second heat exchanger 27 which operates as the evaporator of the heat pump.
• the heat pump may also take up heat from a third heat exchanger 28 which in turn takes up heat from an external heat source (not shown) in the vicinity.
• Additional heat, energy may be supplied to the process by heat generated by the heat pump with its driving means, e.g. heat from cooling water and from exhaust gases from a diesel engine which drives the heat pump and which is symbolised in the drawing by the fourth heat exchanger 29 provided in the evaporator.
• heat generated by the heat pump with its driving means e.g. heat from cooling water and from exhaust gases from a diesel engine which drives the heat pump and which is symbolised in the drawing by the fourth heat exchanger 29 provided in the evaporator.
• the condensator from the product outlet 24 is conducted via a conduit 31 through the heatexchanger/evaporator 27 and, furthermore, the residual liquid is conducted through a conduit 32 which likewise passes through the heat exchanger/evaporator 27. Thereafter, the condensate and the recidual liquid will leave the heat exchanger 27- with substantially the same temperature after - having given of heat .energy in the heat exchanger.
• a condition pertaining to the plant in its entirety should be that the temperatures of the product condensate and the recedual liquid behind the evaporator 27 of the heat pump should be substantially equal to, or even lower than the temperature of the incoming raw liquid 21.
• the column is provided in its upper portion with a gas collecting chamber 33 which communicates with the product water conduit 31 via an evacuation pump 34.
• a further heat exchanger 35 in which water vapor from the gas collecting chamber 33 will be condensed.
• the heat exchanger 35 is provided in the evaporator space, so that the heat exchangers contribute to the evaporation of the raw water sprayed into the evaporator.
• a sub-atmospheric pressure contributing to the evaporation is maintained in the evaporator portion 23 by the aid of the evacuation pump 34 and also by the aid of a low pressure pump 36 with motor 37 disposed in the column.
• the device according to figure 2 differs from the one according to figure 1 substantially only in that the heat exchangers 25, 29 and 35 are adapted to give of there heat inside the evaporator 23 instead off to the raw water conduit as is the case in the embodiment of figure 1.
• the device may be made more compact than is the case according to figure 1.
• the evaporator may be filled with filling elements in order t.o increase the active surface in the evaporator 3,23.
• a heat pump system separate from the distillation system is used for transferring heat energy from the end product, residual liquids and possibly from surrounding heat energy sources to the heating side. Since the heat pump is capable of transferring many times larger amount of energy from a lower to a higher temperature level than what has to be supplied to the pump in the form of mechanical energy, and since furthermore, the pump is capable of utilizing its own heat losses, the energy gain will increase correspondingly compared to if the energy supplied to the heat pump should be directly utilized for heating.
• heat energy at a low temperature in the end products residual products leaving the plant is utilized by means of a heat pump, and this energy as well as a large portion of its own energy consumption including suitable energy from the surrounding is used in the process. Due to its nature the invention may also be applied to most of already existing plant.
• the heat energy of the fresh and salt water leaving the plant is utilized by the aid of a heat pump, so that this heat energy, together with the heat generated by the heat pump and its driving means, may be utilized in the process at an increased temperature level.

Applications Claiming Priority (2)

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• 1982
  • 1982-01-20 SE SE8200293A patent/SE429647B/sv unknown
• 1983
  • 1983-01-18 WO PCT/SE1983/000005 patent/WO1983002445A1/en unknown
  • 1983-01-18 EP EP83900443A patent/EP0100328A1/de not_active Withdrawn
  • 1983-01-18 AU AU11100/83A patent/AU1110083A/en not_active Abandoned

Non-Patent Citations (1)

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