CN1254821A - Absorption-type single-pump refrigerator set with vertically moving membrane - Google Patents

Abstract

An absorption-type single-pump refrigerator set with vertically moving liquid membrane is composed of heat exchangers and the relative fittings, and features that the matched heat medium exchange takes place on the vertically flowing and continuously updating liquid membrane interface. Its advantages include high heat and mass transfer coefficients, simple and compact structure, reliable and convenient operation, small size, light weight, less filled liquid, saving electric energy by more than 1/2, quick start and no pollution.

Description

A kind of vertically moving membrane absorption-type single-pump refrigeration unit

The invention belongs to Absorption Refrigerator.It relates at absorption cold water unit, adopts the vertically moving membrane method to strengthen principle, flow process and the equipment of caloic exchange in absorption-type cold-hot water dispenser group and the absorption heat pump.

The method of refrigeration has varied, main at present two classes of using: liquid evaporation (absorption) and gas expansion method (compression).

Absorption refrigeration is to rely on liquid refrigerant to flash to steam state to absorb heat and freeze (evaporation process), the refrigerant vapour of steam state is absorbed (absorption process) by dense absorbent and becomes weak solution, method concentrating dilute solution with heating is isolated refrigerant vapour (generating process), refrigerant vapour is through condensation liquefy cold-producing medium (condensation process), and then a working cycles has been finished in devaporation.To realize generator, condenser, evaporimeter and absorber and the solution heat exchanger of above four processes, corresponding pump, valve, pipeline and measurement safety instrument are organically combined, and have just constituted a refrigeration unit.

Absorption Refrigerator is power with heat energy.The energy is optional in extensive range, and electricity consumption is few, and noise is low, and is safe and reliable to operation, the varying duty superior performance.Used widely in industries such as central air-conditioning and chemical industry, weaving, pharmacy, information industry, metallurgy.Particularly the CFCs of countries in the world common concern in recent years series cold-producing medium causes serious harm to environment, so the application of absorption refrigeration unit is more and more wide.

It is right that people call working medium to the combination of absorbent and cold-producing medium.The working medium of Absorption Refrigerator is multiple to having.That uses at present in a large number is water-salt worker's confrontation (produce and be higher than 0 ℃ low-temperature receiver) and ammonia-water conservancy project confrontation (produce and be lower than 0 ℃ low-temperature receiver).Easy for discussing, water-lithium bromide is representative (hereinafter to be referred as the bromine cooling machine group) in only verifying with water-salt worker in the present invention's argumentation below, describes application principle and the structure of vertically moving membrane absorption process on Absorption Refrigerator.They also be applicable to basically other working medium to and absorption-type cold-hot water dispenser group and absorption heat pump.

We know, the material Transfer process of water as refrigerant molecule is all taking place for four the i.e. generations of main process, condensation, evaporation, absorptions in the unit.Generating process is water as refrigerant molecule effusion process (needing to replenish heat of evaporation) from solution, condensation process is the coacervation process (need take condensation heat away) that steam state water as refrigerant molecule becomes aqueous water, evaporation process is the liquid refrigerant hydrone effusion process that becomes steam state cryogen molecule (needing to replenish heat of evaporation), and the absorption process coacervation process (need take away and absorb heat) that to be steam state water as refrigerant molecule dissolve in concentrated solution.For the NSC that mass transfer can be carried out is: under certain pressure, concentration conditions, to the maintenance system have certain temperature, need constantly from system, to take away heat (condensation and absorption) or additional heat (taking place and evaporation), need to carry out heat exchange in other words.Heat exchange is that the process that guarantees mass transfer is carried out means smoothly.Obviously the simple heat transfer process that is taken place in this and the solution heat exchanger is distinguishing.

The mass transfer of above-mentioned four main processes is to carry out between the interface of vapour-liquid two-phase.Under the prerequisite that guarantees enough exchange heat, increasing vapour, liquid two contacts the area and the time of contact of interface, interface is brought in constant renewal in, strengthened liquid phase diffusion inside and convection current, reducing the work function of molecule and the generation of the increase nuclei of condensation is effective measures of strengthening mass transfer.

Although commercialization the circulation adopted of bromine cooling machine group and flow process and structural shape varied.But the aggregate that they all are made up of shell-and-tube heat exchanger.Heat-transfer pipe all is a horizontal positioned, and unit is horizontal layout.This layout has been brought a series of significant drawback:

1. under same condition of work, heat transfer, mass transfer effect can not show a candle to vertically moving membrane.Cause deadweight, volume, filling amount, startup behavior in service, the quantifiable indicator of unit all to be not so good as the vertically moving membrane unit.

2. because solution and water as refrigerant from top to bottom pursue when being listed as spray between horizontal tube bundle, can produce and splash, can not adopt the very little through-flow of flow resistance to arrange.

3. sprinkle density is big, needs to use circulating pump to increase spray flux, strengthens power consumption.

4. make cloth liquid evenly very difficult.

5. the unit floor space is big.

6. limited unit to miniaturization, modularization and air cooling development.

In recent years, the vertically moving membrane technology is used for bromine cooling machine,, has become the focus of domestic and international research, but still belong to basic research and small-sized bench test especially for absorption process wherein.About commercial development particularly the vertically moving membrane technology be applied in all directions in four processes of generation, condensation, evaporation, absorption of bromine cooling machine group and still be not reported.

Purpose of the present invention aims to provide a kind of vertically moving membrane refrigeration unit that is suitable for business development.Vertically moving membrane heat and mass method is referred in the processes such as generation in the bromine cooling machine group, condensation, evaporation, absorption.Its circulation process, the effect of each assembly parts and matching way and existing commercialization unit basic identical.Also be by high and low pressure generator, condenser, evaporimeter, absorber, solution heat exchanger, water heater, coagulate heat transmission equipments such as water-to-water heat exchanger, cooling water system, refrigerant water system, solution loop, fluid circuits such as water as refrigerant loop, supporting pump valve, the automatic control measuring system, safety device and attached portion's accessory combine.It is characterized in that using the vertically moving membrane method, the heat and mass transfer process of coupling is occurred on the liquid film interface that flows vertically downward and bring in constant renewal in.Evaporation uses vertical extratubal falling film, tube bank to adopt through-flow to arrange with absorbing.Take place to use vertical multi-turn formula falling liquid film with condensation.Heat-transfer pipe and multi-turn heat transfer plate can adopt with suiting measures to local conditions increases fin, surperficial frosted, be processed into groove, twine silk, coat ways such as silk screen, sintering or thermal spraying porous material strengthens.Adopt custom-designed liquid distributor to guarantee that liquid film can even wetting heat-transfer area.Because falling film evaporation only needs less sprinkle density with absorbing, and can realize uniflow type evaporation and absorption, can economize devaporation (circulation) pump and absorption (circulation) pump, only needs a generating pump, realizes single pump system.

Evaporimeter has bigger influence to the vapour locking between absorber to absorption and refrigerating capacity.Evidence: the every increase of the vapour locking therebetween 1-1.4 millimeter of water, evaporating temperature will change 2.5-3 ℃.For reducing vapour locking to greatest extent, our way is: 1 cancels liquid barrier or adopts the special little liquid-blocking device of novel flow resistance; 2 reduce pipe row number; 3 make the refrigerant vapour stroke the shortest.We have proposed following concrete technical measures for this reason:

(1) adopt special liquid distributor first and liquid distributor once more outside evaporator tube and absorber tube, assurance water as refrigerant and solution are the film shape and evenly descend, and splash phenomena does not take place.

(2) adopt machining or be wound in screw-like outside evaporator tube, the way that increases liquid wetability (spraying or frosted) improves the even malleability of water as refrigerant.

(above two is the prerequisite of cancellation liquid barrier)

(3) should lack along pipe row number on the refrigerant vapour flow direction.

(4) outside absorber tube, twine web material, absorb to strengthen.

(5) shorten stroke from the refrigerant vapour that is evaporated to absorption to reduce flow resistance as far as possible, make on evaporimeter and the absorber cross section to connect for this reason, it is mobile that refrigerant vapour is through-flow.

(6) even need to use liquid-blocking device, adopt the structured packing of flow resistance very little (every meter less than 10Pa).

Commercialization the bromine cooling machine group all adopt three pump systems or at least two pump systems.Have only Shanghai Shen Ma company successfully to develop first horizontal single pump assembly.Be primarily characterized in that evaporimeter adopts from wet tube.Water as refrigerant drips to i.e. fully expansion on copper pipe surface automatically on this kind pipe.Must treat that this tube-surface just drips to next array of pipes after wetting, guarantee under the condition of no pump, to make whole evaporator tubes fully wetting, and stable rapid evaporation absorption refrigeration.

The present invention is provided with the helicla flute bar outside evaporator tube, the water as refrigerant that film forming is descended is from top to bottom evenly fully wetting.Obviously this this horizontal tube is from wetting much easier.When design, should guarantee that the water as refrigerant that is falling liquid film under nominal condition all evaporates.Water as refrigerant does not circulate, thereby has cancelled evaporation pump.Twine silk screen outside absorber tube, solution does not circulate yet, thereby has cancelled absorption pump, has realized single pump system.

Vapour locking between generator and condenser is less to process influence.But, by the dark caused elevation of boiling point of fluid column with prevent that water as refrigerant is contaminated very big to operation control influence.The present invention gives enough concerns to this.For augmentation of heat transfer, improve compactedness in addition, manage on behalf of another with plate, reduce cost, generator adopts vertical multi-turn formula falling liquid film structure with condenser.Adopted following concrete measure simultaneously:

1. adopt efficient low flow resistance liquid-blocking device, as structured packing.

2. the cooling water side effect that high-efficiency fin, particularly condenser are set is more obvious.

3. adopt the phase set type structure, the cancellation water pond also shortens the steam distance.

4. super-huge unit generator and condenser also can be divided into plurality of sections, stacked placement, every intersegmental ventilation interval that has.

The invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is the evaporimeter-absorber top cross-sectional view that is mutually related, and Fig. 2 faces generalized section.Be that individual pen is arranged among the figure, promptly an evaporimeter and an absorber mate.One interior, and another is nested outside.Be applicable to small-sized unit.

In low pressure cylinder 1, be furnished with evaporimeter 2 (being arranged in inner ring) and absorber 3 (being nested) in the outer ring.In fact their position can exchange.Evaporimeter and absorber are all used tubular structure, and division is as follows now:

Evaporator evaporation organ pipe bundle 7 is fixed between upper and lower two header tanks 4 of tool tube sheet.Heat-transfer pipe inside and outside all through strengthening.Experimental results show that the outer winding spring of pipe interpolation bourdon tube is a kind of effective reinforcement way.Be provided with liquid distributor 5 first near the upper cover case.It is a groove that the bottom is a tube sheet.Cloth liquid sleeve pipe (referring to Fig. 4) first is housed on the tube sheet.Its upper edge has the dentation overfall, with the gapped and spiral channel of pipe way so that liquid is circumferentially uniform along pipe.For also guaranteeing on the pipe vertical direction evenly cloth liquid, also be provided with once more liquid distributor 6.Cloth liquid sleeve pipe is shown among Fig. 5 once more.

Water as refrigerant enters into liquid distributor 5 first by inlet 8.From top to bottom vertically moving membrane and evaporation rapidly, the chilled water heat in the absorption tube reaches the purpose of refrigeration.Should guarantee that under nominal condition water as refrigerant evaporates totally fully, not fall into the weak solution of bottom.Adopt single current (not having circulation) evaporation, omitted an evaporation (circulation) pump.

Absorber absorber tube bank 14 is fixed between the two annular seal head casees 11 of tool tube sheet.The inside and outside of heat-transfer pipe also all strengthened.Experimental results show that it is comparatively effectively to strengthen way that pipe interpolation bourdon tube coats the special pressing mesh of one deck outward.The sprinkle density of absorber is big more than evaporimeter, and used liquid sleeve pipe of cloth first and the gap between heat-transfer pipe are bigger, and the number of liquid distributor 13 is also less once more.

Concentrated solution enters into liquid distributor 12 and liquid distributor 13 first once more by inlet 18, and from top to bottom vertically moving membrane is distributed in outside the pipe.Absorb the refrigerant vapour of evaporimeter, become weak solution, be stored in the bottom.Flow out by outlet 17 then.Absorbing hot being flow to by outlet 16 cooling waters of sending by inlet 15 takes away.Adopt single current (not having circulation) to absorb, omitted an absorption (circulation) pump.The refrigerant vapour that evaporimeter produces radially through-flow enters absorber.Flowing like this makes runner short, and flow resistance is little, helps absorbing.In absorber, be provided with exhaust tube 19 to extract fixed gas.

For large-scale and super-huge unit, can adopt being polycyclicly arranged as shown in Figure 3.Evaporimeter and absorber alternately be nested form.Be that 3 evaporimeters and 3 absorbers are formed among Fig. 3.Its operation principle is mobile identical with the individual pen layout with fluid, so repeat no more.

Fig. 6 is that be mutually related generator and cooler faced generalized section.In high pressure cylinder 20, be furnished with low pressure generator 21 (at inner ring) and condenser 32 (in the outer ring) in fact Internal and external cycle can exchange.Low pressure generator and condenser all adopt multi-turn formula structure.Now division is as follows:

Low pressure generator low pressure generator 21 is a multi-circle heat exchanger.Be nested by not connected inner chamber runner 22 and exocoel runner 23 circle circles and form.Interior exocoel all is provided with fin, with expansion secondary heat exchange face.Cavity fluid be height send one imitate refrigerant vapour, 27 advance from exporting 28 to send to condensation from entering the mouth.One imitates the intermediate solution of steam at inner chamber condensation liberated heat heating exocoel, makes its generation (concentrating).Intermediate solution is distributed in the cloth liquid mouth 24 through cloth liquid arm 26 by inlet tube 25.Cloth liquid mouth foreign side on the inner chamber runner, its edge is the dentation overfall, is distributed on the heat-transfer area of exocoel to guarantee the intermediate solution film forming.What take place two imitates refrigerant vapours upwards and around being folded to, and after liquid-blocking device 31 is removed drop, enters into the space of condenser 32, and liquid-blocking device is a venetian blind type, in fill out the low efficient structured packing of flow resistance, not contaminated to guarantee water as refrigerant.Concentrated solution combines in downwards in the concentrated solution liquid bath of bottom.Be sent to the cryogenic fluid heat exchanger through outlet 29.In the concentrated solution groove, also be provided with an overflow pipe 30.In the concentrated solution pipe-line system crystallization takes place, liquid level rises immediately, and the anti-crystallinic pipe automatic crystal dissolving is removed in overflow.

Condenser condenses device 32 also is a multi-circle heat exchanger.Be nested by not connected inner chamber runner 33 and exocoel runner 34 circle circles and form.Interior exocoel all is provided with fin, with expansion secondary heat exchange face.Cooling water is taken away condensation heat by inlet 35 outlets 36.The refrigerant vapour of exocoel is condensed into water as refrigerant and concentrates in the cryogen tank of bottom.Be sent to low pressure cylinder devaporation by outlet 37.For reducing the long and flow resistance of refrigerant vapour stroke in condenser, large-scale unit can be divided into some independently sections with low pressure generator and condenser, leaves logical vapour between every section at interval, and the stack of their stratification is placed.Between the water as refrigerant for the concentrated solution that reduces high temperature and low temperature heat exchange taking place and cause loss of refrigeration capacity, is provided with insulating collar weir 38 between them.

Similar with horizontal absorption refrigeration unit, the branch that hot water, steam, fuel oil, combustion gas are arranged on the vertically moving membrane absorption-type single-pump refrigeration unit thermal source, imitate the branch that single-action, economic benefits and social benefits, triple effect and multiple-effect are arranged on the number, series, parallel, and series connection and the branch of series connection of falling are arranged in the circulation, working medium is to also there being difference.But these do not belong to the scope that the present invention should relate to.Below we are representative with a direct combustion lithium bromide economic benefits and social benefits series connection unit only, the application principle and the flow process of vertically moving membrane method is described.Fig. 7 is the flow chart of its kind of refrigeration cycle.(A and B) also can realize heating circulation by transfer valve 47.

Weak solution after the absorption is extracted out with generating pump 40, through cryogenic fluid heat exchanger 41, is sent in the direct-fired high pressure generator 43 after 42 heating of pyrosol parallel operation.Here we recommend solution heat exchanger request for utilization people invention " a kind of novel heat-exchange device---multi-circle heat exchanger " (ZL-95215477.3) direct-fired high pressure generator request for utilization people invention " a kind of direct combustion angle type high pressure generator " (CN98242333.0).Intermediate solution after the generation is through pyrosol heat exchanger 42, and control valve 48 is sent in the vapour liquid separator 44, and the part refrigerant vapour that flash distillation produces is 46 exocoels that are sent to condenser 32 by the road.Saturated intermediate solution is sent to the cloth liquid mouth of low pressure generator 21 through U type pipe 45, pipeline 25, imitates at exocoel two and takes place.The concentrated solution collection that is concentrated is stored in the concentrated solution groove, and again by pipeline 29, cryogenic fluid heat exchanger 41 cooling backs are sent in the liquid distributor first 12 of absorber 3 by pipeline 18.Film forming decline absorbs refrigerant vapour and becomes weak solution, has finished the solution circulation.

By occurred frequently separate one imitate steam 27 inner chambers that are sent to low pressure generator 21 by the road.The intermediate solution of heating exocoel, and make its generation.The two effect refrigerant vapours that produce enter into the exocoel of condenser 32 through liquid-blocking device 31.Also enter the exocoel of condenser 32 by pipeline 28 at the low saturation water of sending out inner chamber one effect steam condensation.These two strands of cryogens all are condensed into water as refrigerant.Combine in the cryogen tank of bottom.By 8 liquid distributors first 5 that are sent to evaporimeter 2 by the road again after pipeline 37 throttlings, film forming descend and in evaporimeter fully evaporation become refrigerant vapour.Absorbed into weak solution by concentrated solution again and finished the water as refrigerant circulation.

Chilled water and cooling water circulation have been represented very clearly among Fig. 7, repeat no more.

Fixed gas is extracted out by collection chamber 39 and the straight empty pump of exhaust tube 19 usefulness.

For preventing in the concentrated solution system crystallization to take place, the liquid level in the concentrated solution groove rises to when being higher than overflow pipe 30, and the concentrated solution of high temperature overflows to molten brilliant pipe (representing among Fig. 7).

When the energy of supply refrigeration unit is steam (or hot water), need to use steam (or hot water) type high pressure generator.Its structure is similar to above-mentioned low pressure generator, also adopts multi-circle heat exchanger.Different is that inner chamber is walked thermal source steam, rather than one imitates steam; Next is that operating temperature and pressure ratio low pressure generator are wanted height.Fig. 8 is for using the schematic diagram of steam as the attached vapour liquid separator of multi-turn formula vertically moving membrane high pressure generator of thermal source.Fig. 9 is the high pressure generator schematic cross section.Through dispensing branch 55, cloth liquid mouth 56 film forming are distributed on exocoel 52 heat-transfer areas weak solution by inlet tube 54.Taken place by the heating of the thermal source steam (or hot water) of inner chamber 53.Effect steam that takes place and the solution that is concentrated from top to bottom enter in the separator 57.Intermediate solution is sent to high-temperature heat-exchanging by outlet 60, and one imitates steam is sent to low pressure generator by outlet 59 behind liquid-blocking device 58 precipitation of liquid droplets inner chamber, imitates thermal source as two.Thermal source steam (or hot water) is sent to inner chamber by inlet tube 50, coagulates water (or backwater) and sends by 51.The same with horizontal unit, for absorbing heat water-to-water heat exchanger with fixed attention also can be set.Be the kind of fluid in the difference pipeline, among Fig. 7: the weak solution single line Represent the intermediate solution two-wire

Represent concentrated solution with three-way

------on behalf of chilled water, represent the cryogen vapour-liquid to mix usefulness * line-X-X-X represent cooling water to represent exhaust tube with dashed lines------representative with Chinese phonetic alphabet LQ-LQ-LQ with Chinese phonetic alphabet LM-LM-LM-LM to represent the refrigerant vapour double dot dash line to represent water as refrigerant (liquid) to use chain-dotted line

Vertically moving membrane bromine cooling machine group has been saved evaporation (circulation) pump and absorption (circulation) pump and corresponding pipe arrangement, only needs a generating pump, has realized single pump system.Bring following advantage: (1) saves circulating pump water-collecting tray and corresponding pipe valve, makes structure simpler, more convenient operation; (2) make running gear reduce half, not only saved power consumption 1/2 but also improved the reliability of unit operation; (3) even owing to remove the drop effect worsen in high pressure cylinder, water as refrigerant is contaminated, because the circulation of no water as refrigerant, lithium bromide can not aggregation, can only enter into weak solution and go, so can cancel water as refrigerant bypass line and valve, makes structure simpler.Move more reliable; (4) as the water as refrigerant circulation time, as descending suddenly ... .. is obstructed absorption process, and weak solution concentration will rise, and strong solution concentration is too high after taking place, easily crystallization in solution heat exchanger because of equipment gas leakage, refrigeration duty.And now, owing to cancelled the water as refrigerant circulatory system, when above-mentioned abnormal conditions takes place when, evaporation is obstructed simultaneously with absorbing two processes, makes not evaporate most water as refrigerant and fall into solution automatically, only shows as cold and descends, and the unlikely rising of weak solution concentration has reduced the possibility of crystallization greatly; (5) can shorten 1/2～1/3 start-up time.Because of no water as refrigerant circulates as long as condenser one has water as refrigerant to flow to evaporimeter and can enter cooling condition, need not to wait by the time could freeze after accumulating a certain amount of water as refrigerant startup refrigerant cycle pump in the evaporimeter.Secondly strengthen required heat transfer area owing to conducting heat simultaneously with two coupling process of mass transfer and dwindle, facility compact is good, and volume is little, in light weight, filling amount is little, has greatly improved the startup behavior in service, floor space is little, helps unit to miniaturization, modularization and air cooling development.If again with the multi-circle heat exchanger (ZL95215477.3) and the supporting use of direct-fired dihedral high pressure generator (CN98242333.0) of applicant invention.More can bring out the best in each other, constitute a kind of desirable direct combustion economic benefits and social benefits bromine cooling machine group.

Claims (4)

1. a vertically moving membrane absorption-type single-pump refrigeration unit is by high-low pressure generator, condenser, evaporimeter, absorber, solution heat exchanger, coagulate heat transmission equipments such as water-to-water heat exchanger, cooling water system, refrigerant water system, solution loop, fluid circuits such as water as refrigerant loop, supporting pump valve, the automatic control measuring system, safety device and attached portion's accessory combine.It is characterized in that the caloic exchange that is coupled is what to carry out on the liquid film interface of perpendicular flow and continual renovation.

2. a vertically moving membrane absorption-type single-pump refrigeration unit as claimed in claim 1 is characterized in that condenser and absorber adopt tubular structure, all through strengthening, carries out pipe outer wall vertical falling liquid film inside and outside the pipe, and refrigerant vapour realizes that through-flow flows.

3. a vertically moving membrane absorption-type single-pump refrigeration unit as claimed in claim 1 is characterized in that generator and condenser adopt multi-turn formula structure, and interior exocoel all through strengthening, is carried out outer cavity wall vertically moving membrane, and generator and condenser can the segmentation settings.

4. vertically moving membrane absorption-type single-pump refrigeration unit as claimed in claim 1, it is characterized in that absorber and evaporimeter all adopt single current operation (solution and water as refrigerant do not circulate) not need to absorb (circulation) pump and evaporation (circulation) pump, only need a generating pump, realized single pump system.

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