SU1636660A1 - Method of obtaining low temperatures - Google Patents

Abstract

The invention relates to refrigeration engineering, in particular to a method for producing low temperatures using a liquid absorbent, the boiling point of which is close to that of the refrigerant. The aim of the invention is to increase the economic efficiency of the method. The goal is achieved by directing a low-pressure refrigerant from a low-pressure evaporator 3 to the top of a vertically positioned irrigation degasser 4, in which liquid refrigerant absorbs heat from a countercurrent coolant, evaporates to form refrigerant vapors, and in the direction of concentration and amount of refrigerant The temperature decreases and the boiling point rises, then the liquid and vapor refrigerant is transferred from the irrigation degasser 4 to the absorber 7, operating at such same static pressure, and dissolved in a dilute solution. 3 hp f-ly, 3 ill. with SS (L

Description

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The invention relates to refrigeration engineering, in particular to an improved method for producing low temperatures using a liquid absorbent, the boiling point of which is close to that of the refrigerant.

A known method of obtaining low temperatures, according to which the refrigerant is first directed to the first evaporator of the submerged type for evaporation. The resulting steam, along with a portion of the liquid refrigerant, is fed to a second, horizontal, irrigation heat exchanger. Both heat exchangers are connected via steam. The refrigerant vapor coming out of the upper part of the irrigation heat exchanger together with the remnants of the solution after passing through the additional refrigerator is returned to the absorber (USSR author's certificate No. 495506, cl. F 25 V 15/02, 1971)

The disadvantage of this method is low economic efficiency.

There is also known a method of obtaining low temperatures by evaporating a strong solution in a generator to form a weak solution and refrigerant vapor, cleaning the latter in a vertical degasser and condensation in a condenser, then boiling the liquefied refrigerant in a low-pressure evaporator to obtain a refrigerating effect and boiling a part of the liquid refrigerant from the evaporator in degasser (German Federal Standard No. 2758547, cl. F 25 V 15/02, 1979).

The aim of the invention is to increase the economic efficiency,

The goal is achieved by the method of obtaining low temperatures by evaporation of a strong solution in the generator with the formation of a weak solution and refrigerant vapor, cleaning the latter in a vertical degasser and condensation in a condenser, then boiling the liquefied refrigerant in a low-pressure evaporator to produce a cooling effect and boiling part liquid refrigerant from the evaporator in the degasser; the boiling of a part of the liquid refrigerant in the degasser is performed by successive heat exchange with the propulsion unit imis countercurrent coolant and refrigerant entering

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from the collector to the evaporator, with the formation of refrigerant vapor, and the liquid and vaporous refrigerant formed in the degasser in the absorber operating at the same static pressure, is dissolved in a weak solution after the generator.

In addition, before boiling in a degasser, the pressure of the refrigerant from the evaporators operating at different pressures in the tank is equalized to a pressure corresponding to the pressure in the low pressure evaporator, and then the pressure of the refrigerant is increased by a pump to the pressure in the degasser, and the refrigerant in front of the low pressure evaporator in the additional heat exchanger is cooled with coolant from the tank.

The boiling of the refrigerant in the degasser can be carried out by heat exchange with a third-party coolant.

Supercooling of the refrigerant after the degasser before the evaporator is carried out in the final refrigerators by heat exchange with the refrigerant vapor after the evaporator.

Figure 1 shows the refrigeration and absorption parts of a single-stage absorption refrigeration unit; FIG. 2 shows the same three-stage absorption refrigeration unit; FIG. 3 — an irrigation degasser of an absorption refrigeration unit with a built-in cooling coil for subcooling the deaerating absorber washing liquid.

This exemplary embodiment illustrates the operation of an absorption refrigeration unit using a liquid absorbent, the boiling point of which is not very different from the boiling point of the refrigerant. The working pair is ammonia-water with a difference in boiling points of 133 ° C or monomethylamine-water with difference in boiling points, 106.5 ° C.

Single-stage absorption refrigeration unit contains collection 1, refrigerator 2, evaporator 3, irrigation degasser 4 into which coolant is supplied with countercurrent coolant 5 leaving coolant part 6 of the plant, absorber 7 into which diluted solution 8 is fed from the absorber and the concentrated solution is removed 9 using a pump 10.

When implementing the method using a three-stage absorption refrigeration unit, the latter additionally contains tanks 1I, a pump 12, a heat exchanger 13 (FIG. 2).

The method is carried out as follows.

In the case of a single-stage absorption refrigeration unit (Fig. 1, the refrigerant from collector 1 is fed through an additional refrigerator 2 to the evaporator 3, usually operating in a flooded evaporator mode with a constant level. From the evaporator 3, and at the interface, located at the farthest distance possible the distance from the point of entry of the refrigerant, part of the refrigerant is withdrawn from the circuit and directed to the irrigation degasser 4. In the irrigation degasser 4, the refrigerant withdrawn from the circuit drains from top to bottom. Its quality and concentration are continuously reduced, and the boiling point rises. Refrigerant coolant 5 is fed into the irrigation degasser 4 with countercurrent refrigerant. As it moves upwards it cools. In the evaporator 3, there is a normal heat exchange between the refrigerant and the refrigerant coolant 5, as a result of which the latter comes out of of this part of plant 6 is cooled. If the temperature of the refrigerant coolant entering the upper heat exchange register of the irrigation degasser 4 is low enough, then in the lower the heat exchange register of the irrigation degasser 4 can be pre-cooled by the refrigerant coming from the collector 1 to the evaporator 3, or the subcooling of another refrigerant coolant can be carried out.

Liquid residual solution from the bottom of the irrigation degasser 4 is fed to the corresponding absorber 7 with a natural gradient. At the same time, outgoing from the point located above the lower heat exchange register of the irrigation degasser 4, and its upper part, as well as from the evaporator 3, are passed to the absorber 7 after passing through the final chiller.

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Mixer 2 refrigerant vapors, residual liquid solution and refrigerant vapors are dissolved in the diluted solution 8 supplied to the absorber 7 and discharged as a concentrated solution 9 from the absorber using a pump 10.

In the three-stage absorption refrigeration unit (FIG. 2), the process of withdrawing a part of the refrigerant from the circuit is, in principle, carried out in the same way and therefore only the features of the multi-stage installation will be discussed below.

Of all the flooded evaporators 3, 3 (a sufficient amount of refrigerant is removed, which is collected in the tank 11, the static pressure in which is equal to the pressure in the evaporator 3 operating at low pressure. With the help of a pump 12, the refrigerant from the tank 11 is supplied with an increase in pressure to the corresponding value irrigation degasser 4, 25 Irrigation degasser 4 operates at the same pressure as the evaporator of the maximum pressure stage. The refrigerant discharged to it from the circuit is preliminarily passed through the heat exchanger to 13, in which the subcooling refrigerant flowing into the low pressure evaporator 3.

In the upper heat exchange register of the irrigation degasser, just like in a single-stage installation, the refrigerant evaporates from the flowing down liquid film, cooling at the same time

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lodging coolant from state 5 to state b. In addition, the refrigerant from the tank 1, if necessary, MOSNESO supercool in the lower heat exchange register of the irrigation degasser 4. After exiting

the hearth is additionally cooled in the final refrigerators 2 and ..

The residual solution from the lower part of the irrigation degasser 4 together with the refrigerant vapor coming from its upper part is dissolved in the high pressure solution supplied to the absorber 7 (previously, it 5 as a dilute solution 8 is fed to the low pressure absorber 7, and then to the absorber 7, where its saturation occurs. From the high pressure absorber 7, a concentrated 5 coolant leaves the degasser before it goes to the evaporators 3 and 3

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solution 9. The solution is transported by pump.

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According to a preferred embodiment of the invention, in accordance with FIG. 3, in the irrigation degasser A, over its upper heat exchange register, there is a cooling coil 14, in which the supercooling of the washing solution 15 is performed to flush the gases coming from the deaerating absorber. The coolant in the cooling coil 14 is used as the coolant discharged from the flooded evaporator, which is collected in a tank.

11, is transported by a pump 3 2 and takes heat from the refrigerant in the heat exchanger 13, supercooling it. The residual solution is in the same way as in the case of the installation shown in Fig. -1, together with the refrigerant vapor exiting

irrigation degasser 4, solution - 25 the coolant is pumped into the diluent solution 8 supplied to the absorber 7. As a result, a concentrated solution comes out of the absorber 7.

the pressure in the degasser, and the refrigerant in front of the low-pressure evaporator, the additional heat exchanger is cooled with refrigerant from the tank.

Claims (4)

Invention Formula 1, A method for producing low temperatures by evaporating a strong solution in a generator to form a solid solution and refrigerant vapor, cleaning the latter in a vertical degasser and condensing in a condenser, then boiling the liquefied refrigerant in a low-pressure evaporator to obtain a cooling effect and boiling a portion of the liquid refrigerant from the vaporizer in the degasser, characterized in that the boiling portion of the liquid refrigerant in the degasser is carried out by successive heat exchange with moving countercurrent coolant and refrigerant coming from the collection in -. vaporizer the refrigerant, and the liquid and vaporous refrigerants formed in the degasser in the absorber, operating at the same static pressure, are diluted in a weak solution after the generator. 2. The method according to p. 1, differing from that with the fact that the pressure is equalized before boiling in the degasser 0 refrigerant from evaporators operating at different pressures in the tank to a pressure corresponding to the pressure in the low pressure evaporator, and then raise the pressure refrigerant through the pump to the pressure in the degasser, and the refrigerant in front of the low-pressure evaporator in the additional heat exchanger is cooled with the refrigerant from the tank. 3. Method according to paragraphs. 1 and 2, it is ensured that the refrigerant in the degasser is boiled by heat exchange with an external heat transfer medium. 4. Method according to paragraphs. 1-3, this is due to the fact that the supercooling of the refrigerant after the degasser before the evaporator is carried out in the final refrigerators by heat exchange with the refrigerant vapor after the evaporator. Yu