RU2295677C2 - Absorption-membrane installation - Google Patents

Abstract

FIELD: refrigeration industry; heat-and-power engineering; other industries; production of the absorption- membrane installations.

SUBSTANCE: the invention presents the absorption- membrane installation, which ensures production of cold and heat energy working as the thermal pump by extraction from the strong solution of the refrigerant through the semi-permeable membrane under the pressure exceeding the osmotic pressure formed by the pump, the boiling of the refrigerant heated from the external source of the low-potential power at the low pressure with production of the refrigerating effect and absorption of the formed vapors by the weak solution of the refrigerant with production of the heat energy of the condensation and dissolution. The pressure under the membrane is maintained above the pressure of the refrigerant boiling at the environmental temperature. The expansion refrigerator is installed streamwise the refrigerant weak solution and behind the membrane block with usage of the mechanical power of the expansion refrigerator onto the drive of the pump and (or) on the drive of the booster-compressor compressing the vapors of the refrigerant till their mixing with the refrigerant weak solution and absorption. The invention usage will allow to expand the capabilities of the installation.

EFFECT: the invention ensures expansion of the capabilities of the installation.

5 cl, 6 dwg

Description

The installation can be used in refrigeration, air conditioning, as well as in power plants and for heating facilities.

Known lithium bromide absorption refrigeration unit for the production of cold by separating from a weak solution of refrigerant, boiling it at low pressure to obtain the refrigerating effect and absorption of the resulting vapors with a strong solution when the installation is in the mine. The release of refrigerant from a weak solution is conducted through a semi-impermeable membrane under a pressure higher than the osmotic pressure, which is created by a column of water having a height corresponding to the depth of the shaft (see AS SU 1078216, 1984).

The disadvantage of this method is the limitations of its use - only in the mine, only to get cold and only using boiling refrigerant.

The closest analogue of the claimed invention is an absorption-membrane unit for producing cold and thermal energy in the heat pump mode by isolating a coolant from a strong solution through a semipermeable membrane under a pressure higher than the osmotic pressure created by the pump, and the pressure under the membrane is maintained above the boiling pressure of the refrigerant at ambient temperature and the boiling point of the refrigerant heated from an external source of low potential energy, at low pressure to obtain a refrigerating effect and tions formed vapor refrigerant weak solution to obtain heat energy of condensation and dissolution (see. US patent 4,152,901, 08.05.1979).

The objective of the invention is to expand the capabilities of the device.

The problem is achieved due to the fact that the absorption-membrane unit for producing cold and thermal energy in the heat pump mode by separating coolant from a strong solution through a semipermeable membrane under a pressure higher than the osmotic pressure created by the pump, and the pressure under the membrane is maintained above the refrigerant boiling pressure at ambient temperature boiling a refrigerant heated from an external source of low potential energy at low pressure to obtain a cooling effect and absorption the vapor produced by a weak refrigerant solution to produce thermal energy of condensation and dissolution, according to the invention is equipped with an expander installed in the flow of a weak refrigerant solution after the membrane unit using the mechanical energy of the expander to drive the pump and (or) to drive the booster compressor, which compresses the refrigerant vapor until mixing them with a weak solution of refrigerant and absorption.

Lowering the boiling pressure of the refrigerant and intensifying the process of absorption of refrigerant vapor with a weak refrigerant solution is carried out by an ejector that is connected in series with the flow of a weak refrigerant solution, sucking in refrigerant vapor, mixing them with a weak refrigerant solution, compressing the mixture and directing the mixture to absorption.

The refrigerant is released sequentially on a semipermeable membrane at a pressure higher than the osmotic from a strong first-stage refrigerant solution with an increase in the absorbent concentration in a weak refrigerant solution and the subsequent release of high-purity refrigerant at a pressure higher than the osmotic in the second refrigerant recovery stage.

The release of refrigerant from a strong refrigerant solution and an increase in the concentration of absorbent in a weak refrigerant solution is carried out stepwise with the number of steps more than two.

The installation is equipped with an additional absorption-membrane installation in which a heat engine for producing mechanical energy is installed sequentially through the flow of refrigerant vapors after boiling it at high pressure, the refrigerant vapors after the heat engine are absorbed with a weak solution at low pressure during cooling, and the refrigerant is heated during boiling.

In the proposed installation, various refrigerants can be used both in the vapor-liquid phase and in the gas phase to obtain the thermal energy of dissolution of the refrigerant in the absorbent.

Figure 1 presents the absorption-membrane installation for producing cold and thermal energy in the heat pump mode.

The installation consists of a high pressure pump 1, a membrane unit 2, control valves 3, 4, an evaporator 5, an absorber 6. A consumer of cold 7 is connected to the evaporator, and a heat consumer is connected to the absorber 8. There are no restrictions on the installation location. Various refrigerants and absorbents may be used.

Installation works as follows.

Preparing for work.

Completing the installation with instrumentation, protective and regulating devices, evacuating and filling the installation with a solution of refrigerant and absorbent must be performed in accordance with the rules for the technical operation of refrigeration units, depending on the refrigerant used.

Start.

When the control valve 3 is closed and 4 is open, the high pressure pump 1 is started. By closing the control valve 4, the necessary pressure of a strong refrigerant solution is set above the semi-permeable membrane in the membrane unit 2. After the pressure above the membrane is set higher than the osmotic one, the refrigerant will be released from the strong solution refrigerant. The refrigerant pressure under the membrane will increase as refrigerant accumulates under the membrane, when the refrigerant pressure under the membrane reaches pressures above the boiling pressure of the refrigerant at ambient temperature, which will mean that the cavity under the membrane is filled with liquid refrigerant, control valve 3 opens and the refrigerant starts to flow to the evaporator.

After the refrigerant is released, a weak refrigerant solution will appear at the outlet of the membrane unit 2 and a low partial pressure of the refrigerant will be established, since the installation was previously evacuated.

The evaporator is connected to the absorber by a pipeline, or the evaporator and absorber are made in one housing, therefore, a low pressure will also be established above the surface of the refrigerant in the evaporator, at which the refrigerant will boil due to the heat taken from the consumer 7, absorbing the heat of vaporization of the refrigerant. The refrigerant vapors entering the absorber 6 are absorbed by a weak refrigerant solution, and the heat of condensation and dissolution of the refrigerant by the absorbent is released, which is used by the heat consumer 8.

Regulation in the process.

Regulation boils down to maintaining the pressure of the strong solution above the membrane above the osmotic, and below the membrane above the boiling pressure of the refrigerant at ambient temperature.

Figure 2 presents the absorption and membrane unit for producing cold and thermal energy in the heat pump mode using an ejector 9 to further reduce the boiling pressure of the refrigerant and to intensify the absorption process.

Preparation of the installation for operation, start-up and regulation are performed in the same way as in the installation shown in figure 1.

Connecting the ejector 9 allows you to use the potential energy of a weak refrigerant solution to lower the boiling pressure of the refrigerant due to the suction of refrigerant vapor by the ejector, in which a weak refrigerant solution flows at high speed from the nozzle to the diffuser in the form of liquid droplets. In this case, intensive mixing of the refrigerant vapor with drops of a weak refrigerant solution is carried out, which intensifies the absorption process. Further compression of the mixture in the ejector diffuser allows to reduce the boiling pressure of the refrigerant due to suction and to carry out absorption at the lowest absorption pressure, since the contact area of the vapor with a weak refrigerant solution is maximum.

Figure 3 presents a diagram of an absorption-membrane unit for producing cold and heat energy in the heat pump mode using a two-stage refrigerant recovery, which makes it possible to obtain refrigerant from difficultly separated solutions. At the first separation stage, in the membrane block 2, refrigerant is released at the pressure of pump 1 and the membrane design, which allows to extract as much refrigerant as possible. After that, again increase the pressure of the allocated refrigerant by the second pump 10 and on the membrane 11 to get already clean refrigerant.

The installation is started when valves 3, 12 are closed. After starting the pump 1, valve 4 sets the refrigerant discharge pressure in the membrane unit 2.

After increasing the pressure of the refrigerant in the pipeline to the pump 10 and, accordingly, in the membrane block 11 to 3 above the vaporization pressure of the refrigerant at ambient temperature, the control valve 3 opens and the pump 10 is turned on, which creates a pressure above the osmotic block above the membrane 11.

The release of refrigerant under the membrane 11 is controlled by a control valve 12 so that it does not fall below the vaporization pressure of the refrigerant at ambient temperature. The boiling and absorption processes do not differ from the corresponding processes in the installation shown in figure 1.

In the process, regulation is reduced to regulating the pressure drops across the membrane blocks 2, 11. In the case of using pump 1 with a pressure equal to the sum of the pressures higher than the osmotic pressure in the membrane blocks 2, 11, pump 10 is not needed.

Figure 4 presents a diagram of an absorption and membrane unit for producing cold and heat energy in the heat pump mode using multi-stage refrigerant and absorbent recovery. Multi-stage refrigerant and absorbent recovery is necessary to obtain ultra-low boiling points of the refrigerant. The release of refrigerant in a multi-stage installation does not differ from that described above. The two-stage extraction of the absorbent is carried out without an additional high pressure pump. Pump 1 is used. The material of the membranes 15, 16 must have opposite properties, i.e. release absorbent and retain refrigerant. Subsequent stages of refrigerant and absorbent recovery require the use of additional pumps.

Preparation of the installation for operation, start-up and regulation are performed in the same way as in the installation shown in figure 3.

Figure 5 presents a diagram of an absorption membrane installation for producing cold and heat energy in the heat pump mode using an expander. A piston or rotary pump can be used as an expander. The expander 18 allows you to return part of the energy spent in the pump 1 to increase the pressure and pumping the solution through the membrane unit 2. Pump 1 and the expander 18 can be combined on one shaft. The expander can reduce energy costs for driving a high pressure pump up to 50%.

Preparation of the installation for operation, start-up and regulation are performed in the same way as in the installation shown in figure 1.

Figure 6 presents a diagram of an absorption-membrane installation for producing mechanical energy in the mode of a heat engine. As the engine 19, a steam piston engine or turbine may be used. The purpose and principle of operation of the components of the absorption membrane installation does not change. The refrigerant boils in the evaporator 5 at a high temperature and pressure, and the absorption in the absorber 6 at a low temperature and pressure. The temperature conditions of the evaporator 5 and the absorber 6 are created by an external heat source 21 and an external cold source 22. If there is only a low-grade heat source, an additional absorption-membrane unit can be used as an external heat source (see Fig. 7). In this case, the heat engine absorber 6 is combined in one unit with the evaporator 27 of the cooling unit, and the heat engine evaporator 5 is heated by the cooling medium after the absorber 28 of the heating unit. In the presence of external sources of low potential heat and cold, the absorption-membrane unit with a heat engine can operate from these sources.

Preparation for operation, start-up and regulation do not differ from the processes described above.

Example 1. The installation can be implemented according to the scheme of figure 1 using commercially available components. Consider the operation of a theoretical absorption-membrane refrigeration-heating installation, assembled on the basis of the reverse osmosis installation "Sharya-M500", commercially available NPP "Biotehprogress". The Sharya-M500 installation should be equipped with a reverse osmosis element for seawater SW30-2540. For the operation of the reverse osmosis element, a supply of source water in the volume of 1.4 m ³ / h at a pressure of 6.9 MPa is required, while the yield of pure water is 83 l / h. These parameters correspond to the Sharya-M500 installation, in which the feed water is supplied to the element 1.0-1.35 m ³ / h at a pressure at the inlet to the high-pressure pump 0.15-0.3 MPa. In order to provide a pressure of 0.15-0.3 MPa at the inlet of the high-pressure pump, it is necessary to provide a booster pump with a capacity of at least 1.0 m ³ / h and a pressure of at least 0.15 MPa. The specified conditions are satisfied by the Kama 10 domestic pump.

In the installation, the design of the evaporator and absorber can be applied, similar to the design of the evaporative-absorber drum of the HAB-3 installation, with a corresponding resizing.

The refrigerant is water, the absorbent is sodium chloride NaCl (sodium chloride). Since the refrigerant used is water, the process proceeds in a deep vacuum. The installation is filled with NaCl solution with a concentration of the same as that used for testing reverse osmosis elements SW30-2540 (3.5% solution), which corresponds to a salt content of 3.5 kg NaCl in 100 kg of solution. By interpolating the tabular data “Physical properties of aqueous solutions of sodium chloride” we determine the specific gravity of the solution, which will be equal to 1.024 kg / l at 15 ° C.

According to the table "Vapor elasticity over solutions of sodium chloride in mm Hg" we determine the vapor pressure in the evaporator and absorber.

We assume that the ambient temperature in the absorber is the same and equals + 6 ° С.

The vapor pressure in the absorber at a temperature of 6 ° C for a specific gravity of 1.024 is 6.86 mm Hg. (by interpolating the numbers 6.88-6.82 of the table "Vapor Elasticity over Sodium Chloride Solutions, mmHg). In accordance with the scheme, a refrigerant is supplied to the evaporator from the membrane unit — water purified from salt. The degree of purification is 99.2-99.4%.

The free surface above the solution in the absorber is much larger than the surface above water in the evaporator; therefore, the vapor pressure of the absorber 6.86 mm Hg will be established in the evaporator above the water surface. Excess water vapor generated in the evaporator (at a temperature of + 6 ° C, vapor elasticity of 7.01 mm Hg) is absorbed by the solution in the absorber, and the temperature in the evaporator drops to 5.7 ° C, which is the cooling effect .

The proposed design of the absorption-membrane refrigeration unit is idealized, since thermal pressures and the ratio of the surfaces of the evaporator and absorber are not taken into account. The capacity of the membrane unit for the refrigerant will be 83 l (kg) / hour. The heat of vaporization of water at a temperature of + 6 ° C is 593.9 kcal / kg. The cooling capacity of the installation is 83 × 593.9 = 49293.7 kcal / hour (57328.57 W).

Energy costs for pump drive:

- High pressure pump. Maximum power consumption 3 kW.

- The booster pump "Kama 10". Power consumption 0.4 kW.

The total power consumption, excluding energy costs for evacuation, is 3.4 kW.

Refrigeration coefficient 57.328: 3.4 = 16.8, heat dissipation in the absorber when using the unit in the heat pump mode when using the unit as a heating unit 57.328 kW + 3.4 kW = 60.7 kW.

Example 2. Absorption-membrane installation for producing cold and thermal energy using a jet apparatus (ejector). The intended area of application is air cooling in the processing shops for meat and fish products with a temperature inside the workshop + 12 ° С - + 15 ° С and air heating in showers, locker rooms and dryers to a temperature of + 25 ° С at an outside temperature of + 18 ° С.

The refrigerant is water, the absorbent is lithium bromide.

The installation diagram is shown in figure 2

The installation is made from commercially available components.

Installation Composition

1. The high-pressure pump, instrumentation, valves and auxiliary devices are used from the reverse osmosis unit "Sharya-M500", commercially available NPP "Biotechprogress". The feed water supply of 1.4 m ³ / h at 0.15-0.3 MPa. The estimated yield of pure water is 0.083 m ³ / h ≈7%, which corresponds to traditional absorption plants. The pressure of the refrigerant recovery process is 6.9 MPa. The maximum power consumption of the high pressure pump is 3 kW.

2. The booster pump - "Kama-10".

Technical details:

- Nominal volumetric flow - 1.8 m ³ / h;

- Head - 2.0 m (0.2 MPa);

- Height of absorption - no more than 7 m.

The pump must be installed below the absorber by 5 m to ensure the necessary back pressure of the solution on the suction of the pump, since the absorber has a vacuum.

3. Evaporator - GUNTNER air cooler is used. Izhevsk Type 0718/34.

Heat exchange surface - 340 m ² .

Cooling capacity - 60.3 kW at a temperature head of 7 ° C.

Fans - 3 pcs. 0.91 kW each.

Refrigerant inlet - ⌀28 mm.

Vapor output - ⌀64 mm.

4. The absorber. An air cooler of the same company of the following standard size 081A / 34 is used as an absorber.

The heat exchange surface is 369 m ² .

Productivity - 73.9 kW at a temperature head of 7 ° C.

Fans - 3 pcs. 1,280 kW each.

The device is installed in an inverted position, in this case, the corresponding passage sections of the inlet and outlet pipes are provided for the operating conditions.

The inlet of a mixture of vapors and liquids is ⌀64 mm.

The output of a strong refrigerant solution is ⌀28 mm.

5. The ejector. The installation may use an ejector VEZh 25 OST 5.5033-71. Nozzle diameter (d _c ) reduced from 15.1 mm to 2.1 mm as calculated. The remaining sizes of the ejector are stored according to OST 5.5033-71. The bore of the nozzles for connecting the ejector to the air cooler and absorber is selected for the nozzles of these devices.

At a working pressure of the solution of 7 MPa and a vacuum in the absorber, the ejector nozzle will work as a fuel nozzle of a diesel engine. Spraying the solution allows you to intensify the process of absorption of refrigerant vapor and at the same time regenerate part of the potential energy of a weak refrigerant solution. Together, this reduces the pressure in the absorber and, accordingly, in the evaporator.

In the ejector nozzle, the potential energy of a weak solution (pressure 7 MPa) is converted into kinetic. The fluid velocity at the exit of the nozzle according to the calculation is 115 m / s.

In the technical literature there are no methods for calculating ejectors for the above conditions.

By the ratio of the kinetic energy of the flow of a weak refrigerant solution to the kinetic energy of steam in a steam ejector chiller, taking into account operating temperatures, the temperature in the evaporator due to the use of an ejector will be reduced by 3 ° С.

Thermotechnical characteristics of the installation with an ejector,

Unit cooling capacity

Q _ou = G · r,

where G is the amount of refrigerant vaporized in the air cooler - 83 kg / h

r is the heat of vaporization of the refrigerant at a boiling point of + 6 ° C 593.9 kcal / hour

Q ₅ = 83 · 593.9 = 49293.7 kcal / h (57.33 kW)

The 071 V / 34 air cooler has a R22 refrigerant capacity of 60 kW at a temperature head of 7 ° C, which provides an air temperature in the refrigerated rooms of +13 - + 14 ° C, a boiling point of 7 ° C.

Thermal load on the absorber (condenser).

Q ₆ = Q ₅ + L

O ₆ = 57.33 + 4.5 = 61.83 kW

The heat of dissolution of the refrigerant is much less than the heat of condensation, so it is not taken into account.

The heat exchange surface and the performance of the 081 A / 34 device are selected with a margin of QaAB = 73.9 kW.

The temperature head on the absorber is the same as on the air cooler 7 ° C.

Absorption temperature 18 ° C + 7 ° C = 25 ° C.

Refrigeration coefficient 57.33: 3.5 = 16.38.

Energy consumption for the operation of fans 6.57 kW.

Example 3. An absorption-membrane unit for producing cold and thermal energy using a two-stage refrigerant recovery and increasing the concentration of absorbent in the solution.

A two-stage installation allows you to get a low boiling point of the refrigerant. In this case, lowering the boiling point is achieved by increasing the purity of the refrigerant and by increasing the concentration of absorbent in a weak solution of the refrigerant.

The work of membrane blocks at high concentrations requires an increase in the pressure of the initial solution directed to the membrane block. The increased pressure allows you to build two-stage plants with one high pressure pump.

At a pump pressure of 150 kg / cm ^2, it is possible to use a membrane unit of the first stage operating at pressures: inlet - 150 kg / cm ² , refrigerant outlet - 70 kg / cm ² (ΔP = 80 kg / cm) and the second stage: inlet - 70 kg / cm ² and the outlet pressure is higher than the boiling pressure of the refrigerant at the temperature of the membrane unit. For example, for R22 at a temperature of the membrane block + 25 ° С, the refrigerant pressure should not be lower than 11 kg / cm ² , otherwise the process of boiling of the refrigerant will begin in the membrane with the formation of bubbles, cooling of the membrane below acceptable temperatures and cavitation effect of the refrigerant flow on the membrane material.

In the case of an absorption-membrane unit of the first stage, coarse separation of solutions occurs, presumably on a nanofiltration membrane, in which as much refrigerant as possible is released, at a pressure much higher than the osmotic one and with the use of a membrane material that allows a large amount of refrigerant to be released. In this case, the concentration of absorbent in a weak refrigerant solution after the first stage increases, which helps to reduce the partial pressure above a weak solution of refrigerant in the absorber and, accordingly, leads to a decrease in pressure in the absorber and evaporator. The refrigerant after the first stage is cleaned of absorbent impurities in the second stage of cleaning and sent to the evaporator, and the weak refrigerant solution formed after the second stage, bypassing the absorber, immediately enters the pump.

Example 4. An absorption-membrane unit for producing cold and thermal energy using multi-stage refrigerant recovery and a multi-stage increase in the concentration of absorbent in a weak refrigerant solution.

The two-stage refrigerant recovery from a strong refrigerant solution is described above. Multistage is basically the same. The multi-stage isolation of the absorbent requires a special membrane material, which allows the absorbent to pass through and retain the refrigerant.

The possibility of creating multi-stage membrane blocks to increase the concentration of absorbent sent to the absorber is confirmed by information on means for measuring the composition of multicomponent mixtures.

Given that through fluoroplastic membranes, permeability decreases with increasing molecular weight of hydrocarbons, and through rubber it increases (see Farzane N.G. Technological Measurements and Instruments, Moscow: Higher School, 1989, p. 361) and that hydrocarbons are widely used in refrigeration installations and the fact that the molecular weight of absorbents, as a rule, is much larger than the molecular weight of the corresponding refrigerant, it is possible to create single or multi-stage membrane blocks to increase the concentration of absorbent, which in its own Eating leads to increased installation efficiency.

Example 5. Absorption-membrane installation for the production of cold and thermal energy using an expander.

ROCHEM has experience in using expanders in water treatment or desalination plants. The company uses expanders to reduce energy costs for driving a high pressure pump. As an expander, piston axial or rotary pumps can be used.

ROCHEM, a water treatment plant, regenerates up to 50% of the energy used to drive a high pressure pump.

The use of an expander should not exclude the use of an ejector, since an ejector is necessary to intensify the absorption process.

Part of the energy of the high pressure pump can be regenerated in the expander, part in the ejector, for example, in the expander after the second stage of refrigerant recovery, and after the first stage in the ejector. If a significant reduction in the boiling point of the refrigerant is required, the expander can be connected to a compressor (turbocharger), which will operate as a booster compressor.

Example 6. Installation for the production of mechanical energy using an absorption-membrane installation.

A heat engine typically requires a heat source and a cold source to condense the vapors. High potential energy is supplied to the evaporator 5 from an external source 21. When the refrigerant is boiled at high temperature, high pressure refrigerant vapors are formed. The vapor of the high pressure refrigerant is supplied to the engine 19. On the second side of the engine, the vapor pressure of the refrigerant is low due to the cooling of the absorber 6 from an external cold source 22. The pressure drop of the vapor of the refrigerant ensures the operation of the engine 19. Mechanical work is spent on the drive of the high pressure pump 1 and drive external devices 20.

Figure 7 shows a special case of an absorption-membrane installation for the production of mechanical energy when there is no source of cold for the operation of a heat engine. A heat engine is considered, for which only a heat source with a temperature of + 28 ° C is required, the second absorption-membrane unit serves as a cold source.

A theoretical dual absorption-membrane unit consisting of the following devices is proposed for consideration.

1. Installation operating as a heat engine. The refrigerant is ammonia, the absorbent is water or ammonia salts of NH ₄ CNS.

2. Installation operating in the mode of obtaining cold and thermal energy. The refrigerant is water, the absorbent is lithium bromide; or lithium chloride; or zinc bromide; or sulfuric acid.

The temperatures at which the second unit will operate t ° _o = + 5 ° C, t ° _k = + 35 ° C, allow the use of a bromistolithium absorption-membrane unit. Refrigerant water - heat of vaporization 594 kcal / kg. When implementing a lithium bromide installation, an ejector and an expander are used, the use of multi-stage refrigerant and absorbent recovery is not considered, since this complicates the installation.

Thermal balance.

where Q ₆ is the heat of vapor absorption of the refrigerant in the absorber 6;

Q ₅ is the heat of boiling of the refrigerant in the evaporator 5;

Q ₁₉ is the heat consumed by the engine 19;

L ₁ - operation of the high pressure pump 1;

Q ₂₈ is the heat of vapor absorption of the refrigerant in the absorber 28;

Q ₂₇ is the heat of boiling of the refrigerant in the evaporator 27;

L ₂₃ - operation of the high pressure pump 23;

L ₂₄ - the operation of the boost pump 24;

L ₃₁ - operation of the coolant pump 31.

1/3 of the operation of high pressure pumps is regenerated by expanders.

The efficiency of converting thermal energy into mechanical energy is about 20%.

Q ₁₉ = Q ₅ · 0.2

The heat of the absorber 6 is equal to the heat of the evaporator 27, since the devices are combined in one unit, which makes it possible to equate O ₆ = Q ₂₇ ,

For the left side of the equation to have a positive value, it is necessary that the water from the pump 31, cooling the absorber 28, be heated Δt≈2 ° C, and in the evaporator 5 cooled Δt≈4 ° C, that is, the source water must be cooled.

The right side of the equation is an expression of useful work

или

or

L = Q ₅ -Q ₂₈

To implement a dual installation, the following technical characteristics of component parts are necessary:

- Lithium bromide installation (heat pump)

- The high-pressure pump of the installation from the desalination plant KRO-030-V (Korea), with the following characteristics.

- Q _us . ₂₃ = 15 l / min (0.9 m ³ / h)

- P _us . ₂₃ = 155 kg / cm ²

N _us.2 = 6 kW.

Booster pump.

- Q ₂₄ = 18 m ³ / hour

- P ₂₄ = 1.1 ÷ 1.5 kg / cm ²

- N ₂₄ = 0.5 kW

Membrane block 25, ejector 29, expander 30, evaporator 27 and absorber 28 should ensure the release of refrigerant from the solution in an amount of 0.135 m ³ / h (15%) and boil it at a temperature t ₀ = + 5 ° C. The expander 30 is used to return the energy of the drive of the high pressure pump 23 in an amount of 1/3. The remaining energy of a weak refrigerant solution is used in the ejector 29.

Electricity consumption by a 6.5 kW heat pump installation excluding an expander, including an expander

Cooling capacity Q ₂₇ = 135 kg / h · 594.5 kcal / kg = 80257 kcal / h (93.33 kW).

The heat released in the absorber Q ₂₈ = 93.33 + 4.5 = 97.83 kW

The cooling water of the absorber 28 has a temperature of + 28 ° C and in the absorber heats up to + 30 ° C. Absorption temperature + 35 ° C.

Ammonia unit 1 (heat engine).

The refrigerant is ammonia, the heat of vaporization at a temperature of + 25 ° C is 278.66 kcal / kg.

The high pressure pump 1 must provide a greater capacity than in installation 2.

We accept the increase in installation 1 compared to the heat pump installation 2 2.3 times

- Q _nas.1 = 0.9 x 2.3 = 2.07 m ³ / h

- P _us.1 = 155 kg / cm ²

- N _us.1 = 6 · 2.3 = 13.8 kW

The membrane unit and the rest of the equipment should ensure the release of 15% ammonia 2.07 · 0.15 = 0.31 m ³ / h, boiling it at a temperature of + 25 ° C and absorption at a temperature of +7 - + 8 ° C. The evaporator of unit 2 and the absorber of unit 1 are combined in one unit, presumably a plate heat exchanger, a temperature difference of 2 ÷ 3 ° C, Q ₆ = Q ₂₇ .

The expander 18 in the installation is used to return the energy of the drive of the high pressure pump 1 in the amount of 1/3.

Ammonia plant cooling capacity:

Q ₅ = 310 kg / h · 278.66 kcal / h = 86384 kcal / h (100 kW).

Heat Q ₅ can be converted into mechanical energy with a conversion efficiency of 20%, which will be 100 · 0.2 = 20 kW. From this, it is necessary to drive the pumps, taking into account the return of 1/3 of the energy using the expander:

Installation

Installation

Total circulation pump for water supply 31 N = 2 kW

Total: 15.7 kW

Generated 20 kW, spent 15.7 kW, the possible receipt of mechanical energy of 4.3 kW.

Heat absorber installation 1.

Q ₆ = 100-20 + 13.8 = 93.8 kW

The condition Q ₆ = Q ₂₇ is satisfied: 93.8≈93.33.

The result of the work of such a dual absorption-membrane unit will be the production of mechanical energy of 4.3 kW by heating the unit from an external energy source - water with a temperature of + 28 ° C.

Water with this temperature is available in unlimited quantities in tropical areas of the ocean.

Claims (5)

1. An absorption-membrane unit for producing cold and thermal energy in the heat pump mode by separating a coolant from a strong solution through a semipermeable membrane under a pressure higher than the osmotic pressure created by the pump, the pressure under the membrane being maintained above the boiling pressure of the refrigerant at ambient temperature, and the boiling of the refrigerant heated from external source of low potential energy, at low pressure with the receipt of the refrigerating effect and absorption of the resulting vapors with a weak solution of refrigerant obtaining thermal energy of condensation and dissolution, characterized in that it is equipped with an expander installed in the flow of a weak refrigerant solution after the membrane block using the mechanical energy of the expander to drive the pump and (or) to drive a booster compressor, compressing the refrigerant vapor before mixing them with weak refrigerant solution and absorption. 2. The installation according to claim 1, characterized in that the lowering of the boiling pressure of the refrigerant and the intensification of the process of absorption of refrigerant vapor by a weak refrigerant solution is carried out by an ejector that is connected in series with the flow of a weak refrigerant solution, sucking in refrigerant vapor, mixing them with a weak refrigerant solution, compressing the mixture and directing the mixture to absorb. 3. The installation according to claim 1, characterized in that the refrigerant is released sequentially on a semipermeable membrane at a pressure higher than the osmotic from a strong first-stage refrigerant solution with an increase in the concentration of absorbent in a weak refrigerant solution and the subsequent release of high-purity refrigerant at a pressure higher than the osmotic in the second stage refrigerant emissions. 4. The installation according to claim 3, characterized in that the selection of refrigerant from a strong refrigerant solution and an increase in the concentration of absorbent in a weak refrigerant solution is carried out stepwise with the number of steps more than two. 5. Installation according to any one of claims 1 to 3, characterized in that it is equipped with an additional absorption-membrane installation, in which a heat engine for producing mechanical energy is installed in series with the flow of refrigerant vapor after boiling it at high pressure, the refrigerant vapor is absorbed after the heat engine a weak solution at low pressure while cooling, the refrigerant is heated during boiling.

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