JPH05272837A - Compression absorption composite heat pump - Google Patents

Abstract

PURPOSE:To reduce the temperature of a generator through the increase of refrigerant density of the generator and perform effective utilization of the exhaust gas heat of a prime mover required for vaporization of a refrigerant in the generator by a method wherein vapor from a vaporizer is compressed in an absorber by means of an intermediate mechanical compressor, and the absorber is operated by means of the pressures of the generator and the vaporizer. CONSTITUTION:Concentrated ammonia liquid is fed from an absorber 4 to a generator 1 through a heat-exchanger 5 with the aid of a circulating pump 6 and vaporized by means of an exhaust heat, and the vaporized ammonia liquid is guided to a condenser 2 and condensed by a cooler 102. Vapor generated from a vaporizer 3 by means of a main compressor 20 is guided to the condenser 2 with the aid of a prime mover 30, heat is removed by the vaporizer 3 and a heat of condensation is removed by means of the condenser 2. Exhaust heat used for drive of a mechanical compressor has heat which is reduced through the feed of it to the generator 1 by means of a line 33. Meanwhile, in cooling water of the prime mover, since ammonia concentration is increased by the intermediate condenser 2 and thus a vaporizing temperature is low, heat is sufficiently received by a low temperature heating source and a quantity of heat can be effectively utilized.

Description

Detailed Description of the Invention

[0001]

[Industrial field of application] This relates to heat pumps that produce cold and hot water from the wastewater of factories produced from the manufacturing processes of each industry, the treated water from sewage treatment plants, and heat sources such as the sea and rivers.

[0002]

When the exhaust gas of a prime mover that drives a mechanical compressor is used as a heat source for an absorption refrigerating machine, the most preferable method for improving the thermal efficiency is a generator, a condenser and an evaporator. And the refrigerant from the evaporator in the absorption heat pump consisting of four units is compressed by the mechanical compressor and sent to the condenser, and in the system of the absorption heat pump, the heat pump of the conventional compressor is used. By incorporating the system, all the heat of the compressor is taken out of the system by the condenser. The refrigerant that can be used at this time is
Freon and ammonia are mainly used, and as an absorbent, a combination of water and an organic solvent having a low vapor pressure is effective.

When the above complex system is operated by cogeneration, the method of generating exhaust heat differs depending on the type of prime mover used, that is, when a gas engine is used, the exhaust gas from the gas engine and the gas engine are cooled. There are two ways of heated warm water. The former heat-recovers an object having a temperature of about 500 ° C. as exhaust gas and exhausts it into the air at 180 to 190 ° C. On the other hand, the exhaust heat of a normal gas engine of a small size of about 100 kW recovers about 50% of the amount of heat only by the gas engine cooling water, and it is necessary to further increase the recovery rate. The larger the size, the lower the exhaust heat recovery rate due to the gas engine cooling water,
It becomes 30 to 50%, and 20 to 30% of exhaust gas will be recovered. The present invention relates to cooling water only and effective use of both, and operates at a temperature lower than the temperature of the generator of an ordinary absorption heat pump.

When a gas turbine is used as a prime mover, exhaust heat is exhaust gas only, and in order to effectively utilize this exhaust gas, it is necessary to construct a system capable of recovering heat at a low temperature in the complex system. Specifically, it is necessary to absorb the exhaust heat of the gas turbine by lowering the temperature of the generator. In the conventional method, the temperature of the generator is 110
Although the temperature is higher than or equal to ℃, 70 to 80 ℃ is preferable for heat recovery.

Conventionally, the temperature of the generator is 90 to 120 ° C. in the case of the lithium bromide system when cold water is obtained.
Before and after, hot water cannot be produced. Therefore, when a CFC-based or ammonia-based working fluid is used, the temperature of the generator is around 110 to 140 ° C., and it cannot be heated by the cooling water discharged from the gas engine. Even in the case of a gas turbine, it is far from perfect heat recovery.

In the case of a gas engine, there is also a method of cooling the gas engine with water to generate steam having a pressure of 1 kg / cm ² . Since it is handled as a boiler, it has not been generalized because it is difficult to operate in small or medium-sized plants.

[0007]

The combined compression and absorption heat pump according to the present invention includes a refrigerant, an absorbing liquid that absorbs the refrigerant, and the refrigerant and the absorbing liquid that are in contact with each other to absorb the refrigerant into the absorbing liquid. An absorber for heating, a generator for heating the absorbing liquid that has absorbed the refrigerant inside to evaporate the refrigerant from the absorbing liquid, and a refrigerant that has evaporated inside for cooling the refrigerant by heat exchange with the external first fluid. A condenser that liquefies the refrigerant and heats the first fluid, and an evaporator that heats the refrigerant liquefied inside by a heat exchange action with the external second fluid to vaporize the refrigerant and cool the second fluid. A compressor, a first compressor for flowing the vaporized refrigerant from the evaporator to the condenser, and a prime mover for driving the first compressor, and generate exhaust heat of the prime mover, gas, and heated cooling water. Used to heat the absorbing liquid in the Flow medium. Compressing the vapor from the evaporator (the amount needed to run the absorption refrigeration system) into the absorber using a second (intermediate) mechanical compressor and operating the absorber at generator and evaporator pressures Thus, the temperature of the generator can be lowered by increasing the refrigerant concentration of the generator. On the other hand, by lowering the pressure of the generator to lower the design pressure of the generator and the condenser, the equipment cost is reduced.

[0008]

FIG. 1 shows the configuration of an embodiment of the system according to the present invention. Absorption heat pump generator 1, condenser 2,
An evaporator 3, an absorber 4, a concentrated liquid heat exchanger 5, and a concentrated liquid pump 6 are provided, an exhaust gas heater 101 and a cooling water heater 105 are provided in the generator 1, and a condenser 2, an evaporator 3 are provided.
Heat exchangers 102, 103 and 104 are attached to the absorber 4 and the absorber 4, respectively. The compressor 20 including the subcooler 7 is driven by the prime mover 30, and the intermediate compressor 21 is also driven by the prime mover 30. Fuel is supplied to the prime mover, and its exhaust gas is connected to the generator,
The prime mover cooling water likewise circulates between the generator and the prime mover. When circulating the working fluid to the condenser 2 as in another embodiment of the invention in FIG. 2, a lean liquid pump 22 and a lean liquid heat exchanger 23 are provided.

The operation of this embodiment when a water-ammonia system is used as the working fluid will be described with reference to FIG. An exhaust gas heater 101 from a prime mover 30 is attached to the generator 1, and a heater 105 for heating the cooling water of the jacket is also provided.
Is installed. The concentrated ammonia liquid is supplied to the generator 1 from the absorber 2 by the circulation pump 6 via the heat exchanger 5, where the exhausted heat causes the concentrated ammonia liquid to evaporate, which is guided to the condenser 2 and the cooler 102. Is partially condensed and is partially supplied to the evaporator 3 through the subcooler 7, where it is heated by the heater 103 by brine and partially supplied to the absorber 4 by the circulation compressor 21, where it is generated. Since it is mixed with the dilute ammonia solution from the vessel 1 to generate heat of absorption, this heat of absorption is removed by the cooler 104 and condensed. The discharge port of the main compressor may be connected to the absorber 4 and the refrigerant from the evaporator 3 may be sent to the absorber 4.

The absorption heat pump system is completed as described above. On the other hand, the evaporator 3 by the main compressor 20
The vapor of 1 is driven by the prime mover 30 and guided to the condenser 2, and can perform two of the heat removal by the evaporator 3 and the heat removal by the condenser 2. The important point of co-generation is that the heat pump is driven by a mechanical compressor, and the exhaust heat used to drive it, that is, the combustion gas, is sent to the generator 1 by the line 33 as described above, so that the temperature is lowered and the heat is recovered. Easy to peel off. On the other hand, the cooling water of the prime mover has a high ammonia concentration due to the above-mentioned principle due to the intermediate compressor, and therefore has a low evaporation temperature, so that it can sufficiently receive heat even at a low temperature heating source, that is, at a temperature of 80 to 90 ° C. it can. As described above, the heat load of this system uses about 35% of the supplied heat amount as exhaust heat of the mechanical compressor or the prime mover, that is, 35 to 50% of the total heat amount.
% Heat quantity can be effectively used for absorption heat pump.
In addition, when the system is used to obtain hot water having a high evaporation temperature of 3 to 4 ° C. and a condensing temperature of 80 ° C., the pressure for condensing the pure refrigerant becomes high, so that the evaporating liquid is condensed with the condenser 2 and the evaporator. It is possible that the pressure in the condenser 2 is lowered by circulating the pressure in the condenser 3. As an example, in the water-ammonia system, pure ammonia has a condensation pressure of 35 kg.
/ Cm ² , but if the ammonia concentration of 80% liquid is circulated, the condensation pressure becomes 15 to 20 kg / cm ² ,
Economical equipment can be designed.

The working fluid used in this system is one in which the refrigerant and the absorbent have a vapor-liquid equilibrium, such as a water-ammonia system, one having a relatively small vapor-liquid equilibrium composed of CFCs and other organic solvents, or water. -Either one having no vapor-liquid equilibrium such as the lithium bromide system may be used.

An ammonia compressor driven by a gas engine having a nominal output of 100 kW has a discharge pressure of 15 to 20 kg / cm ² G, a generator of 70 m ² and a cooling water of the gas engine of 89 to 95 ° C. and a calorific value of 166000 Kc.
The low temperature heater accepts al and has a heat transfer area of 20 m ² . The de-super heater is 5.0 m ² , the condenser is 50 m ² , the evaporator is also 50 m ² , and the heat transfer area of the absorber is 65 m ² . Ammonia rich heat exchange is 1
The flow rate is 4 m ² , the circulation pump is 1600 liter / hr, and the discharge pressure is 10 to 15 kg / cm ² . The intermediate compressor is a 27 KW compressor with a discharge flow rate of 400 kg / hr and a discharge pressure of 10 kg / cm ² G. The heat transfer area of the supercooler is 4 m ² . The column A of Table 1 shows the results when the condensation temperature of the condenser was 40 ° C., the temperature of the evaporator was 3 ° C., and the condensation temperature of the absorber was 40 ° C. using the above equipment. Also, the evaporation temperature is 3 ° C. and the condensation temperature of the condenser and the absorber is 50.
Numerical values of an example when used for heating in the case of ° C are shown in the column B of Table 1. Column C shows the operation results for hot water production at an evaporation temperature of -10 ° C. If no intermediate compressor is provided, the evaporation temperature of the generator is about 1 for A, B and C.
The temperature is 00 ° C, 110 ° C, and 142 ° C, and the exhaust heat of the prime mover cannot be used.

[0013]

[Table 1] (1) Pressure: [kgf / cm ² ] absolute (2) Circulation: [kg / hr] (absorber / condenser) (3) Temperature: [° C] (4) 13A city gas: Nm ³ / hr (5) Calorie: × 10 ³ Kcal / hr

(1) If the absorber at point A is operated at the same pressure as the evaporator at E, the temperature of the generator is determined according to the concentration C1. (2) If the pressure of the absorber currently operating at point A is increased by an intermediate compressor and condensed, the concentration is C1,
The concentration in the generator corresponding to that concentration also increases and the evaporation temperature of the generator decreases. In this way, if the temperature drops, the generator can be operated using cooling water of around 80 ° C.
In addition, due to the high evaporation concentration in the generator, ammonia-
It is not necessary to recirculate even a working fluid with vapor-liquid equilibrium such as an aqueous system. There is no need for a rectification column, a dephlegmator, or reflux, improving thermal efficiency and reducing equipment costs. (3) When the temperature of the condenser and the absorber exceeds 50 ° C, the pressure of the condenser may exceed 20 kg / cm ² , and in such a case, a circulating flow is created between the evaporator and the condenser. As a result, the pressure of the absorber and the generator can be reduced, which is very advantageous in mechanical design and can provide an economical system.

In the embodiment according to the invention having the simplest construction, which is shown in FIG. 4, a generator 1, a condenser 2,
An absorption heat pump including an evaporator 3, an absorber 4, a heat exchanger 5, a circulation pump 6, a heat exchanger 23, and a circulation pump 22 in which a compressor 21 is provided between the evaporator 3 and the absorber 4. Is. The two working fluids (refrigerant and absorbent) used in this heat pump are preferably refrigerants that are gas-evolving and easily mechanically compressed.

When a water-ammonia system is used as the two working fluids, the cold water of 7 ° C. at the evaporation temperature of 3 ° C. of the evaporator 3 and the temperature of the condenser 2 and the absorber 4 are operated at 60 ° C. A facility with an operating capacity of 110 JRT for simultaneous production facility of cold water and hot water to be produced can be operated by the following operations. The temperature of the generator 1 is 90 to 100 ° C., the pressure is 10 (kgf /
cm ² , a), the temperature of the condenser 2 is 60 ° C, the pressure is 10 (kg)
f / cm ² , a), evaporator 3 temperature 3 ° C., pressure 1.5
(Kgf / cm ² , a), the temperature of the absorber 4 is 60 ° C., the pressure is 4.5 (kgf / cm ² , a), the circulating liquid concentration for condensing the evaporative liquid is 50 to 52 wet%, and the circulating amount is 4.
It was 0 ton / hr. The circulation compressor used at this time had a compression ratio of 3.0 and a driving power of 25.0 KW. Without this circulation of the evaporating liquid, the operating pressure of the generator and the condenser would be 26 to 27 (kgf / cm ² , a) and the ratio would be high. The heat input to this regenerator is 195,000.
(Kcal / hr).

[0017]

As described above, when the water-ammonia system is used, the evaporation temperature of the generator can be freely controlled within the range of 60 to 80 ° C. by providing the intermediate compressor. Therefore, the cooling water of the gas engine can be used to heat the generator, and the mechanical compression heat pump can be operated using the highly efficient gas engine that has been desired so far, while the remaining heat quantity can be absorbed. Since it can be used as a heat source for a heat pump system, it is possible to provide an efficient hot and cold water production facility by co-generation.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a heat pump according to the present invention.

FIG. 2 is a schematic view of another embodiment of the heat pump according to the present invention.

FIG. 3 is a diagram showing pressure and temperature states of a working fluid (refrigerant) in a heat pump cycle, where (a) shows a case where an intermediate compressor is provided, and (b) shows evaporative liquid. The case of circulating is shown.

FIG. 4 is a schematic view showing another embodiment according to the present invention.

[Explanation of symbols]

 1 Generator 2 Condenser 3 Evaporator 4 Absorber 5 Heat Exchanger 6 Circulation Pump 20 Compressor 21 Compressor 30 Motor

Claims (4)

[Claims] 1. A compression / absorption combined heat pump,
Refrigerant, an absorbing liquid that absorbs the refrigerant, an absorber that absorbs the refrigerant in the absorbing liquid by contacting the refrigerant with the absorbing liquid inside the absorber, and heat the absorbing liquid that has absorbed the refrigerant inside the absorber to remove the refrigerant from the absorbing liquid. A generator that evaporates, a condenser that cools the refrigerant that has evaporated inside by a heat exchange action with an external first fluid to liquefy the refrigerant and heat the first fluid, and a refrigerant that condensed inside It has an evaporator that heats by a heat exchange action with an external second fluid to vaporize the refrigerant and cools the second fluid, and a first compressor that sends the vaporized refrigerant generated in the evaporator to the absorber. heat pump. 2. The combined compression / absorption heat pump according to claim 1, wherein the second compressor sends the vaporized refrigerant from the evaporator to the condenser. 3. The combined compression / absorption heat pump according to claim 1, further comprising a pump for sending a liquid state refrigerant that has not been vaporized in the evaporator to the condenser. 4. The combined compression / absorption type heat pump according to claim 1, wherein the first compressor is driven by a prime mover, and exhaust heat of the prime mover is used for evaporation of an absorbing liquid in a generator. heat pump.