CN101626816A - Heat transfer method for ocean thermal energy conversion and desalination - Google Patents

Abstract

A method is provided to produce fresh water from seawater on both the boiler side and the condenser side of an OTEC power plant. A portion of the warm sea surface water is evaporated and as the steam condenses, the steam transfers heat to the working fluid boiler. The steam condenses to provide fresh water. On the condenser side, condensation of the working fluid vapor from the turbine in the condenser releases heat that evaporates the seawater flowing along the outside of the condenser surface. The steam from the seawater is condensed by a heat exchanger that uses the colder seawater as input. When the cold seawater accepts heat from the condensing steam, it becomes slightly warmer and provides a source of seawater that accepts heat from the condenser. The steam condensed on the heat exchanger becomes fresh water which flows out as potable water.

Description

The heat transfer method that is used for ocean thermal energy conversion and desalination

The cross reference of related application

The sequence number that the application requires on October 2nd, 2006 to submit to is the priority and the rights and interests of 60/827881 U.S. Provisional Patent Application, and the full content of this application is incorporated this paper by reference into.

[background technology]

OTEC (Ocean Thermal Energy Conversion, ocean thermal energy conversion) device has been used to generating and seawater desalination.In one approach, warm water flash distillation (flash) is a water vapour.In open cycle system, water vapour can drive turbine and be condensed subsequently to produce fresh water.For closed-loop system, warm water is used to boil the working fluid in heat exchanger or is that water vapour is used to by allowing warm water flash distillation, water recovery subsequently on the surface of boiling device to discharge the heat of condensation of water vapour, as United States Patent (USP) 5,513,494 and 4,324,983 is described.The water that condenses is fresh water and can be used by near group.By the cold water condenser of flowing through, working fluid is condensed in heat exchanger usually.

It is evident that for being operated in OTEC industry personnel warm current can be evaporated to steam, described steam will transmit heat and provide fresh water by condensation.This operation occurs in the boiling device side of Thermal Motor.But as unusual be that the cold water of condenser side can be caused flash-off of steam because cold water has the temperature lower than condenser, and will not flow to condenser from the steam of cold water.The invention provides a kind of method that causes the cold water evaporation, and another fresh water sources is provided, it almost is the twice of desalted water total amount from the OTEC device.

For additional fresh water production, the invention provides a kind of method of in desalination unit, using warm water discharging and cooled water discharge.

The present invention not only can use in the OTEC device, and it can also use in other electricity generation system.For example, in geothermal power generation plant, if overheated water can be from underground acquisition, then it can evaporate under pressure.Steam will flow to boiling device, and steam will condense on the boiling device to boil working fluid.The water that condenses will be the distilled water of cleaning.By this description, term " OTEC " is generally used for referring to power set, but should be noted that the present invention can use in the power set of other type.

[summary of the invention]

The preferred embodiment of the invention does not have flash distillation to warm up water, but allows warm water to be downward through the surface also absorbs the warm seawater of introducing from the beginning when it evaporates heat.The surface of steam flow boiling device, its deposits heat on boiling device when steam condenses.Heat boils working fluid to drive turbine.Condensed water runs down also is collected for drinking use.This is similar to prior art a little, and it uses flash evaporation to produce steam from warm water.

Obtain water rather than do not need to be the water droplet gathering system from the mobile water curtain evaporation of water, and, eliminated the formation of mineral matter precipitation owing to there is not the spilling (splashing) of flash distillation water droplet from the benefit that water is flashed to steam.

This system prevent steam flow in the assembly of captive air, and constantly air is removed from system, rather than allows pre-deaerator remove the air of introducing the dissolving in the water.

The design of original OTEC device has uses warm water producing the desalter of desalted water in the boiling device side of system, but the cold side of Rankine-cycle engine (Rankine Cycle Engine) is not used to produce water.In the present invention, cold side is also produced fresh water.Working fluid condensing in condenser provides heat with evaporation water, and water recovery is on the surface of cold-water heat exchanger.Water vapour is collected for drinking use then.

If captive air is in the equally processing of warm water side in the cold water side of system.

Therefore the purpose of this invention is to provide the method on a kind of boiling device that will be transformed into from the heat of warm seawater in the OTEC device, it uses water vapour as heat transmission medium, and not need the water droplet gathering system and to have eliminated the mode that the mineral matter precipitation assembles and carried out.

Another object of the present invention is to collect heat transmission medium, water, and it condenses on the boiling device for drinking use.

Another object of the present invention be to use water vapour as heat transmission medium will be passed to Mare Frigoris water and condensate water steam from the heat of working fluid and to collect water vapour for drinking use.

Another object of the present invention provides the device that removes the air that is hunted down in water vapour, so that air does not hinder condensing of water vapour.

Another object of the present invention is to use warm water of discharging and discharging cold water so that additional fresh water to be provided in desalination unit.

Another object of the present invention is when the boiling device side of system and condenser side rather than OTEC (for example geothermal power generation device) produce desalted water, provides heat to pass to boiling device and from the heat transmission of condenser.

Part below in conjunction with drawings and detailed description illustrates other purpose of the present invention, benefit and new feature and further range of application.And according to following investigation or can be by practice of the present invention is learned, part it will be apparent to those of skill in the art.Especially rely on means pointed in the accessory claim and combination can obtain and realize purpose of the present invention and beneficial effect.

[description of drawings]

Incorporate this specification into and form wherein a part of accompanying drawing showing embodiment of the present invention, and be used from explanation principle of the present invention with specification one.Accompanying drawing only is used to illustrate the purpose of the preferred embodiments of the invention, and can not be interpreted as limitation of the present invention.In the accompanying drawings:

Fig. 1 is the schematic viewgraph of cross-section that is used for system, when this system passes to ebullator with heat from warming up seawater, it produces fresh water from the warm water adnation of OTEC device, and when this system from condenser when Mare Frigoris water transmits heat, it is from the cold water side production fresh water of OTEC device.

Fig. 2 is the schematic cross sectional end view of a design of the cold water side of OTEC device, it shows condenser tubes and the heat exchanger tube that comprises a plurality of working fluid condenser tubes, wherein Mare Frigoris water is from the external evaporation of working fluid condenser tube, when the water vapor transmission heat was given the cold water of introducing, water vapour condensed in heat exchanger tube.

Fig. 3 is the schematic cross-sectional side view of a design of warm water side of OTEC device, it shows a plurality of dip-parallel plates, wherein warm seawater is downward through from the dip-parallel plate with water curtain, and water curtain evaporation when the heat of the warm seawater below the inclined plane is flow through in its collection, and warm steam flow boiling device (not shown) boils working fluid so that heat to be provided.

Fig. 4 is the schematic diagram of multistage desalination system, and this system has used warm water discharging and the cooled water discharge from the OTEC device of Fig. 1.

[specific embodiment]

Fig. 1 schematically shows an embodiment of OTEC device of the present invention, described OTEC device use water vapour as heat transmission medium so that will move to working fluid steam from the heat of warm seawater, and use water vapour as heat transmission medium so that the heat of self cooling condenser is transferred to Mare Frigoris water in the future.Fig. 1 also shows from the fresh water of the warm water side of OTEC device and cold water side and collects.

When warm seawater entered heat exchanger 2 by pipeline 1, warm seawater provided the water curtain 4 of heat to seawater by heat exchanger wall portion, and described water curtain flows downward at the opposite side of emptying chamber 3 mesospore portions.When warm water upwards flow through heat exchanger channel 25, warm water cooling was because warm water release heat is given water curtain 4.When warm water arrived the top of passage 25, the warm water of subsequent section flowed downward at the right side wall portions formation water curtain 4 of emptying chamber 3.Remaining warm water flows out from discharge tube 27.Because the temperature that the warm glassware for drinking water that flows downward with water curtain 4 has is near the temperature that equals submarginal water vapour in the emptying chamber 3, therefore warm water can flash distillation.When warm water evaporated at normal temperatures, warm water absorbed heat.Seawater from the water curtain that flows flows out warm water discharge spout road 10.

Heat exchanger 2 should be enough the high so that pressure that produces by water column can prevent to be positioned at the warm water flash distillation of the bottom of passage 25.Should make suitably that whole unit enough is higher than ocean surface, so that pressure is low in water.

Water vapour flows downward in emptying chamber 3 and be condensed into fresh water film 5 in the wall portion of boiling device 6, and boiling device comprises low boiling working fluid 7.Steam channel 26 to boiling device 6 next doors designs, and water vapour continues to flow downward when becoming narrower with convenient passage.It keeps water vapour to flow downward, and water vapour carries any captive air that originally is dissolved in the water down to channel bottom.When water vapour when the wall portion of boiling device moves, captive air is attempted to press close to film of condensed water 5 and is collected.Because water curtain 5 flows downward under the gravity effect, water curtain 5 attempts to drag air with it.Ejection pipeline 9 allows air (with some water vapours) to be pumped into vavuum pump.This is the method for water deaeration.

Most of warm water is shifted out from pipeline 27, and because the warm water of described major part does not enter emptying chamber 3, so it needn't be by deaerated.Original OTEC invention uses flash evaporation with the heat transferred boiling device, and fresh water production needs all warm water must be by deaerated.

Condensate water 5 is a distilled water, and it flows out for drinking use from water outlet pipeline 8.

The temperature of using water vapour is condensate water as the benefit of heat transmission medium surface 5 and evaporating surface 4 much at one.This is similar to water back, and water back is than the better heat conductor of any metal.Give working fluid if the heat exchanger of routine is used to transmit the energy of water, then, between water and working fluid, have huge temperature difference because water is not good heat conductor.Use water vapour rather than use common heat exchanger to be that as another benefit of heat transmission medium seawater does not contact boiling device and corrosion can be provided and peel off problem on boiling device.

The heat of being supplied with by condensed water 5 boils working fluid 7.The subsequent working fluid steam flows to superheater 11 (if any), and flows to turbine 12 subsequently, and turbine extracts mechanical energy.The heat that is used for superheater can pass through solar energy, bio-fuel, fossil fuel and/or separate stream of warm ocean water supply.When steam left turbine, steam was cold.Steam flow condenser 13, steam condenses into water curtain 14 in wall portion there, and described wall portion cools off by the evaporation that is positioned at the cold-water film 18 on the wall portion offside.The working fluid 14 that is condensed flows to the bottom downwards, and by pump 23 its suction is back to boiling device 6 to repeat this circulation.Water curtain 18 flows downward and discharges by cold-water discharge pipe 22.

In addition, owing to have boiling device, heat transmits by steam in condenser.Working fluid steam is deposits heat in the wall portion of condenser, and the water evaporation is to take away this heat.The rolling water curtain 14 of working fluid and water and water 18 provide fabulous heat transmission.

The water vapour of leaving chilled water water curtain 18 flows to cold-water heat exchanger 16 downwards.Water recovery as fresh water film 19, and flows to fresh water discharge line 20 downwards subsequently in heat exchanger wall portion.The air of catching in the water vapour is transported downwards, and by pipeline 21 by pumping to vavuum pump.Here the degas system that provides is similar to the hot water side degas system.

Should be noted that the Mare Frigoris water meeting heating when it upwards flows through heat exchanger that enters heat exchanger 16 by pipeline 15, because Mare Frigoris water has been accepted the heat from condensation water curtain 19.This heat is from working fluid, because described working fluid is condensed into water curtain 14 and with heat transferred water curtain 18.When the water in the heat exchanger 16 arrived the heat exchanger top, desirable situation was identical with the temperature of water curtain 18.(in fact, this water will be colder a little than the working fluid 14 of condensation, so that the temperature difference that causes heat to flow out from condenser to be provided).The sub-fraction that upwards flows through the water of heat exchanger 16 upwards flows to water dispenser 28, and described injection well downhole flow regulator spreads out water as water curtain 18, flows downward with the wall portion along condenser.The surplus water that upwards flows through heat exchanger 16 is discharged from by pipeline 29.

The temperature of listing on the accompanying drawing is based on the supposition temperature of Celsius' thermometric scale.They are theoretical temperatures.In real system, they will be slightly different because heat exchanger surface lacks efficient.

This system is provided at the method that hot water side and cold water side are all produced fresh water.Water vapour also is used as heat transmission medium, so that will move to boiling device from the heat of warm water, and the heat of self cooling condenser moves to cold-water heat exchanger in the future.

By after idle, when starting, warm water and cold water should at first begin to flow, so that form water curtain at device.Cold water curtain 18 on the condenser will cause condensing of working fluid steam, and will cause steam to flow through turbine 12 and flow to condenser 13 from boiling device 6.That will begin to cool down boiling device 6, and water will begin from warming up 4 evaporations of water water curtain and condensing on the boiling device.

As substituting of the vertical surface that is used to evaporate water curtain, can use inclined surface or even horizontal surface.Referring to Fig. 3, water is flowed provide good heat transmission for water curtain.Another embodiment of the present invention will have open containers, and warm water is allowed to flash distillation in this open containers, and the steam that produces will flow to boiling device.The water droplet that steam produces is along with steam moves.Splash-back will be essential.Drop on lip-deep water droplet and attempt to set up mineral deposit, yet there is not the metal surface in the water that flows with water curtain for mineral deposit thereon there from the water curtain surface evaporation.Adopt flash evaporation at condenser side, cold water is positioned in need on the surface that is connected in condenser.When water and vapor absorption during from the heat of condenser, water and steam are heated up, so that steam pressure will enough flow to heat exchanger surface, described heat exchanger has the Mare Frigoris water of introducing.

Another embodiment of the present invention will have sprayer, and described sprayer is sprayed onto water on the surface that produces steam.When water droplet is shifted to this surface, water droplet will be attempted flash distillation, and water droplet drops on behind the surface flash distillation is more.

Fig. 1 shows simple surfaces, but in fact they will be many flat plate heat exchangers when warm water upwards flow to other passage, and described many flat plate heat exchangers have the water curtain that flows downward that is arranged in emptying chamber alternately.Another method will be to have vertical pipe, and warm water upwards flows through described vertical pipe, and the warm water of a part flows downward as the water curtain on the outside and returns subsequently.Can flow to the outside of boiler pipe subsequently from the steam of water curtain evaporation, and when working fluid boils in pipeline, coagulate at this.

For the working fluid condenser, when cold water during along condenser lateral current downflow, working fluid can condense in the vertical pipe.Can flow to the outside of cold water pipes and condense from the steam of cold water at this.

Fig. 2 shows one embodiment of the invention, and it has described flowing of water and steam on the OTEC device cold side.Fig. 2 shows condenser and holds the end-view that pipeline 50 and heat exchanger hold pipeline 57.After working fluid steam left turbine, working fluid steam flowed into condenser tube 51, and it is shown in the end-view of Fig. 2.Absorb heat and evaporation along the Mare Frigoris water of the lateral current downflow of condenser tube 51 from condenser tube.Taking away this heat causes working fluid steam to condense in the condenser tube.Working fluid liquid is sucked subsequently and returns boiling device.Not shown connecting pipe and the pump that is used for working fluid liquid.

The water along the lateral current downflow of condenser tube 52 of evaporation does not drip the bottom that holds pipeline 50 to condenser downwards, and by pump 62 its suction is entered discharge line 61.

Mare Frigoris water enters pipeline 55, and upwards flows through cold-water heat exchanger 56.These heat exchangers can be pipe or the chambers with rectangular cross section, and described pipe or chamber form by being positioned at four flat boards on the side.Flow into heat exchanger and hold pipeline 57 from being arranged in water vapour that condenser holds condenser tube 52 evaporation of pipeline 50, and condense on the cold-water heat exchanger 56.The water that is condensed drips to the bottom of heat exchanger tube 57 downwards, and flows out from pipeline 60 as fresh water.

When Mare Frigoris water upwards flowed through cold-water heat exchanger 56, Mare Frigoris water became warm by absorbing from the heat that is positioned at the condensate water on the cold-water heat exchanger outer surface.Most of upwards flowing water flow goes out discharge line 61, but some water flow by control valve 58, by pipeline 59 and by water dispenser 53, and described water dispenser distributes water along the evaporator overhead condenser pipe.After water flowed around the evaporator overhead condenser pipe, water flowed to next-door neighbour's low condenser tube etc. downwards.Metal tape 52 between the condenser tube even help provides water flowing from a pipe to another pipe.

As parallel substituting as shown in Figure 2, condenser tube 51 can be vertical, and water can begin from the top of each pipe and flow downward with the water curtain form along each pipe.

Centigrade desirable water temperature is depicted as an example of a series of conditions in the temperature shown in many points of equipment.Their purpose is to help the reader understanding what has taken place.

Fig. 3 is the explanatory view of a layout of heat on the warm side of OTEC device and steam transmission mechanism.Warm seawater enters pipeline 77 and is assigned with and enters in the warm water channel 75, and flows to the right side.The major part that should warm up water is collected and discharges by pipeline 73.The fraction water that flows in the passage 75 is by water dispenser 74, and flows downward with water curtain along the upper face of the inclination of passage 75 subsequently.When water curtain 71 flowed downward, the part water curtain absorbed from the heat of the water that flows in the passage 75 and evaporates.The water that flows to pipeline 75 right sides is owing to the cooling that becomes to water curtain 71 release heat.Flow out pipeline 70 from the water vapour of water curtain 71 evaporations, and flow to the working fluid boiling device, water vapour condenses and discharges the heat that condenses at boiling device and gives boiling device.The water that flows in water curtain 71 of evaporation does not fall to the bottom of container 72, and is sucked in the discharge tube 73 by pump 76.

In addition, the temperature of listing with Celsius temperature is the ideal temperature that is used for an example of possible condition.

In the example of Fig. 1, although cooled water discharge is at 10 ℃, warm water discharging is at 22 ℃.This temperature difference can be used in and produces more fresh water.Fig. 4 shows an example of the multistage desalination unit that can do like that.

In Fig. 4, enter by pipeline 30 and by warm seawater chamber 31 from the warm water discharge flow of OTEC device, and the warm marine stream of some of them is by water dispenser 32, and flows to the left side downwards as water curtain 33 along adjacent chamber 39.Flow through that pipeline 36 enters and by cold water chamber 38 from the cooled water discharge of OTEC device, and flow downward as water curtain 37 along the right wall portion of some emptying chambers 39.From the water of the heat of vaporization that warms up seawater from water curtain 33, described water curtain 33 flows downward along the wall portion adjacent with warm seawater chamber.Water vapour flows around deflector (baffle) 35 and condenses in the left wall of warm hydroecium 39 portion, and heat is passed to the water curtain 37 that flows by wall portion.This process continues to run through each stage and enters cold water chamber 38 up to heat flow.Each chamber is from right to left than colder towards the chamber on its right side.

If steam flows with in the left wall portion that is condensate in each chamber from the evaporation water curtain of the circulating water that directly passed through the chamber, it will carry captive air therewith.Air will " pile up (stack up) " and be resisted against on the water curtain that flows downward along Zuo Bibu, and air layer will hinder steam to condense.By deflector being placed on chamber central authorities, captive air is carried to the bottom, chamber along the left wall portion of deflector 35 by water vapour downwards.Flowing downward of water curtain 34 also helps air is moved down.When the air gets bottom, air next-door neighbour water curtain 34 flows out.Air (with some water vapours) by pipeline 40 by pumping to vavuum pump.

Seawater discharges by pipeline 41, and fresh water flows out pipeline 42 simultaneously.

Fig. 4 shows three emptying chambers, and three emptying chambers have been represented the three phases of dewatering unit, but relies on available temperature difference between warm water and the cold water input temp, can have emptying chamber more or still less.

Claims (8)

1. A power and fresh water generation system comprising A source of warm water for heating; and A source of cold water for heat dissipation; and a first heat exchanger for cooling said warm water, which provides heat to an evaporating flowing water curtain of warm water on an outer surface of said first heat exchanger, thereby providing water vapor; and channels for conducting said water vapor to heat exchange surfaces of a working fluid boiler; and conduits for conducting the working fluid vapor from the boiler to a turbine that extracts mechanical energy from the working fluid vapor; and a condenser for receiving the working fluid vapor exhausted from the turbine and for condensing the working fluid as a liquid on an inner surface of the condenser; and a pump that draws the working fluid liquid back into the boiler; and a second heat exchanger for condensing water vapor on an outer surface thereof when the heat of condensation slightly heats the cold water flowing in the second heat exchanger; and channels for transferring the slightly warmed cold water from the second heat exchanger to the outside surface of the condenser, and the water flows down the outside surface of the condenser to taking heat from the condensed working fluid as heat to evaporate the water, the water vapor flows to the second heat exchanger where the water vapor condenses and slightly heats the cold water; wherein the warm water is slightly cooled by evaporation of a curtain of warm water flowing outside the first heat exchanger, the curtain of warm water being provided by a portion of the slightly cooled warm water, and wherein from the steam from the flowing curtain of warm water transfers heat to the boiler to boil a working fluid, the steam condenses on the boiler and is pumped back as potable water; and wherein the working fluid steam to the turbine, and then to the condenser, the water vapor condenses on the inner surface of the condenser and flows down to the pump to be drawn back into the boiler; The second heat exchanger is slightly heated, and the slightly heated cold water flows to the outside surfaces of the condenser and flows down along these surfaces as a water curtain, and the cold water curtain absorbs the water in the condenser heat of the condensed working fluid, and wherein the heat absorbed by the water curtain produces water vapor, which flows back to the second heat exchanger and condenses while heating the cold water, and the condensed The water vapor flows downward and is pumped out as potable water. 2. The power and fresh water generation system of claim 1, wherein said water vapor from said first heat exchanger entering said passageway in said boiler flows in such a way that trapped air Drag to the end of the channel where the trapped air is sucked out by a vacuum pump. 3. The power and fresh water generation system of claim 1 wherein said water vapor from the outside surface of said condenser flows into channels in said second heat exchanger in a manner intended to be captured The air is dragged to the end of the channel, where it is sucked outside by a vacuum pump. 4. The power and fresh water generation system of claim 1, wherein a superheater is provided between said boiler and said turbine so that when said working fluid vapor flows from said boiler to said turbine When it is further heated, the superheater can supply heat through warm water or other heat sources. 5. The power and fresh water generation system of claim 1, wherein said water curtain evaporation method is replaced by a flash evaporation method. 6. The power and fresh water generation system of claim 1, wherein said water curtain evaporation method is replaced by a water spray evaporation method. 7. A desalination system receiving a warm brine discharge and a cold brine discharge from a power plant similar to that described in claim 1 for producing potable water, said desalination system comprising : A warm chamber that draws warm brine that cools as it flows down through the chamber, releasing heat to evaporate water from the flowing curtain of warm brine, whose a curtain of flowing water flowing down the wall of the adjacent evacuation chamber; and cold water chambers that draw cold brine that is heated as it absorbs heat from condensation of water vapor on the walls of adjacent chambers; a plurality of evacuation chambers located between the warm water chamber and the cold water chamber; and a saline distributor located at the top of each of said evacuated chambers to provide a saline water curtain such that the water curtain flows down along said chamber wall, wherein said heat from a warm water chamber flows through a wall of said chamber to heat said curtain of brine flowing down said wall of said adjacent evacuated chamber, and some of said brine The water curtain evaporates and the steam flows to the opposite wall of the chamber and condenses to form potable water and deposits heat on the wall through which it flows causing The curtain of brine flowing down the walls of the chamber partially evaporates, and where this process is repeated in all of the evacuated chambers until the last evacuated chamber, steam condenses in the cold water chamber. On the walls, and within each chamber, salt water flows down to the bottom of the chamber and out to discharge the salt water, and fresh water flows down to the bottom and is collected as potable water. 8. The desalination system of claim 7, wherein baffles are placed in each evacuation chamber to push the water vapor with its trapped air upward near the top of the chamber, thereby It is made to flow down the condensed surface so as to drag the trapped air to the bottom of the chamber where it is drawn out by a vacuum pump.

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