JPS6222059B2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] (Field of Industrial Application) The present invention uses a combination of an absorption heat pump and a compression heat pump to generate high temperature by using waste heat such as waste hot water as a low heat source. Regarding how to generate.

(Prior Art) As a method of effectively utilizing waste heat that is discarded in the form of heated waste water, etc., there is a method of raising the temperature using a heat pump, and its application fields are expanding. There are two types of heat pump methods: compression heat pumps and absorption heat pumps. The compression type requires high-value mechanical power such as electricity, and as the temperature rise range increases, the benefits decrease in terms of waste heat recovery and the unit cost of generated heat. On the other hand, waste heat such as heated waste water has a low temperature level, so if you want to obtain the required high temperature of 100℃ or more using only an absorption heat pump, you will need a multi-stage absorption heat pump, which makes the entire device extremely difficult. It has disadvantages such as being large.

There is also a method of using a combination of a compression heat pump and an absorption heat pump in order to reduce the above-mentioned drawbacks of the prior art. For example, JP-A-52
The combination heat pumps described in JP-A-69041 and JP-A-53-43266 have a compression type on the low-temperature side and an absorption type on the high-temperature side. The primary refrigeration cycle must become a high-temperature heat source in order to operate the absorption refrigerator that constitutes the secondary refrigeration cycle, and therefore the temperature increase by the compressor of the primary refrigeration cycle is limited. It became necessary to increase the
A large compressor is required. Moreover, if the high-temperature side is an absorption type, problems such as corrosion and a decrease in the capacity of the absorber of the absorption type heat pump due to the contamination of non-condensable gases will occur.

In addition, as a combination method using an absorption type on the low temperature side and a compression type on the high temperature side, for example,
There are heating and cooling methods listed in the issue. However, this known method requires a high-temperature heat source made of steam or the like in the generator of the absorption chiller in order to generate a refrigeration effect in response to the changing cooling load. Since it is difficult for a low temperature heat source to meet the cooling load requirements, it is extremely difficult for known methods to operate efficiently with such a low temperature heat source.

(Problems to be Solved by the Invention) As described above, each of the conventional techniques has its own problems. The present invention relates to a high temperature generation method that uses an absorption heat pump on the low temperature side and a compression heat pump on the high temperature side, and effectively utilizes a relatively low temperature heat source such as waste hot water to obtain a desired high temperature. The object of this invention is to eliminate the various problems mentioned above in the prior art.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, the high temperature generation method of the present invention utilizes a low heat source with a temperature higher than the cooling water in the generation part of the second container of the absorption heat pump. Concentrating the dilute solution and cooling and condensing the generated vapor refrigerant with the cooling water in the condensing section of the second container; introducing the liquid refrigerant into the evaporating section of the first container of the absorption heat pump; evaporating with a low heat source, absorbing this refrigerant vapor in an absorption section of the first container by a concentrated solution introduced from the generation section, and introducing the diluted solution as a result of absorption into the generation section; The medium temperature obtained by the heat obtained in the generation part and the absorbed heat obtained during the absorption is used as a heat source to evaporate the refrigerant liquid of the compression type heat pump, and after compressing this refrigerant vapor, it is led to a condenser and condensed into liquid. and obtaining a high temperature.

(Function) Concentrating a dilute solution using a low heat source in the generation section of an absorption heat pump, cooling and condensing the generated vapor refrigerant (e.g. water vapor) in the condensing section, and evaporating this liquid refrigerant in the evaporation section using a low heat source. The generated vapor refrigerant is absorbed into a concentrated liquid in an absorption section. A compression heat pump using the absorption section as an evaporator is operated, and the heat held by the high-pressure, high-temperature refrigerant is supplied to the load fluid in the condenser to obtain a required high temperature.

(Example) Embodiments of the present invention will be described based on the drawings.

FIG. 2 shows the performance of a compressor using a screw compressor as an example. As you can see from the figure,
The coefficient of performance (=amount of heat generated/input mechanical power) of a heat pump using a screw compressor is strongly influenced by the temperature increase width, and as the temperature increase width increases, the coefficient of performance decreases rapidly.

Figure 3 shows the temperature rise of an absorption heat pump when the difference between the exhaust heat source usage temperature and the cooling water temperature is 20°C, and a lithium bromide (LiBr) aqueous solution is used as the working medium. This shows an example of the required number of stages. As you can see from the figure, 70℃
If you want to raise the temperature to a certain extent, a minimum of four stages are required.

On the other hand, general absorption heat pumps can raise the temperature by about 20℃, and if the temperature of the heat source is about 50℃, for example, in the case of a heat pump that generates a high temperature of about 100℃ to 120℃, the temperature increase will be Width: 50℃~
Since the temperature is 70°C, it is possible to improve the coefficient of performance by 1 to 2 by combining a single-stage absorption heat pump and a compression heat pump.

FIG. 1 shows a specific system diagram, in which an absorption heat pump is used on the low temperature side and a compression heat pump is used on the high temperature side.

1 is the first container of the absorption heat pump and the evaporation part 2
and an absorbing section 3. A second container 4 of the absorption heat pump is composed of a generation section 5 and a condensation section 6. The compression heat pump consists of a compressor 7, a condenser 8, an expansion valve 9, and an evaporator 11 made up of a plurality of evaporation pipes 10. 12 is a cooling tower, 13, 14, 1
5 is a circulation pump.

To explain the pipe system that communicates the first container 1 and the second container 4 of the absorption heat pump, 26 is a dilute solution pipe, 27 is a concentrated solution pipe, and 28 is a water pipe through which liquid refrigerant water flows. Regarding the pipe system in which heated waste water is communicated with the first container 1 and the second container 4 as a heat source for the absorption heat pump, 20 is a main pipe for supplying heated waste water;
21 and 22 are branch pipes for supply, and 23 and 24 are branch pipes for outflow. The cooling water flow path communicating with the cooling tower 12 is composed of an outflow pipe 30 and an outflow pipe 31.

The refrigerant flow path of the compression heat pump includes an inflow pipe 32 for low-pressure medium-temperature refrigerant vapor, and a discharge pipe 3 for high-pressure high-temperature vapor.
3. It consists of a high-pressure refrigerant liquid outflow pipe 34.

Next, a method of generating high temperature using the heat pump of this embodiment will be explained.

First, to explain the operation of the absorption heat pump system used on the low temperature side, a dilute solution of lithium bromide and water is introduced from the dilute solution pipe 26 into the generation section 5 of the second container 4, while the branch pipe 21 The refrigerant is heated and evaporated by a low heat source such as heated waste water introduced into the generating section 5 through the refrigerant, thereby generating a vapor refrigerant. As a result of the evaporation, the concentrated solution of lithium bromide is introduced by the circulation pump 13 through the concentrated solution tube 27 into the absorption section 3 of the first container 1 .

The vapor refrigerant generated in the generation section 5 of the second container 4 flows into the condensation section 6 in the same container, where it is cooled by cooling water introduced from the cooling tower 12 through the inlet pipe 30 by the circulation pump 15. Condense. The liquid refrigerant that has become condensed water is transferred to the first container 1 via the water pipe 28 by the circulation pump 14.
is introduced into the evaporation section 2.

The liquid refrigerant introduced into the evaporation section 2 of the first container 1 is
The vaporized refrigerant is heated and evaporated by the heated wastewater introduced through the branch pipe 22, and then reaches the absorption section 3 in the same container, where it comes into direct contact with the concentrated solution of lithium bromide introduced into the absorption section 3. As a result, it is absorbed into the solution, generating heat of absorption. As a result of absorption,
The diluted solution is again introduced into the generating section 5 of the second container 4 through the dilute solution tube 26.

Next, to explain the operation of the compression heat pump system used on the high temperature side, "the plurality of evaporation tubes 10" in the absorption section 3 of the first container 1 constitute the evaporator 11 of the compression heat pump. 1st
The refrigerant of the compression heat pump, which has been heated to a medium temperature by receiving the medium temperature obtained by the heat obtained in the evaporation section 2 and the absorbed heat obtained in the absorption section 3 in the evaporation tube 10 in the container 1, is transferred from the evaporator 11. After being sucked into the compressor 7 through the inflow pipe 32 and compressed, it is introduced into the condenser 8 through the discharge pipe 33, and heat is supplied to the fluid to be heated (load fluid) flowing through the circulation pipe 16, and the fluid is heated to a required high temperature. Heat to. The high-pressure refrigerant liquid liquefied in the condenser 8 is passed from the outflow pipe 34 to the expansion valve 9.
After that, it reaches the evaporation tube 10 in the absorption section 3 again and evaporates.

In addition, in order to effectively utilize the sensible heat of the dilute solution, heat exchange is performed between the dilute solution and the concentrated solution.
A heat exchanger can be installed between the dilute solution tube 26 and the concentrated solution tube 27.

According to the above-described high temperature generation method, the refrigerant vapor reaching the suction side of the compressor can be raised to a medium temperature higher than the temperature of the external heated waste water. That is,
The vapor refrigerant (water vapor) of the absorption heat pump, which is heated and evaporated in the evaporation section 2 of the first container 1 by receiving heat from the heated waste water of a low heat source from the outside, reaches the absorption section 3 of the same container and becomes a concentrated solution. The evaporation tube 10 of the compression heat pump exchanges heat with the heat exchanger, which is further heated due to the exothermic phenomenon caused by the absorption.
The refrigerant liquid flowing through the tank will be heated to a medium temperature higher than the temperature of the heated waste water.

For example, if the temperature of heated waste water, which is an external low heat source, is 70°C, the refrigerant vapor evaporated in the evaporation tube 10 of the compression heat pump will have an intermediate temperature of 88°C when it is sucked into the compressor 7. Therefore, the temperature of the load fluid in the condenser 8 can be increased to 110°C.

Note that it is of course possible to heat the evaporation part 2 and the generation part 5 of the absorption heat pump by different low heat sources as necessary, instead of heating them by the same low heat source as described above. .

〔Effect of the invention〕

In the present invention, the refrigerant vapor sucked into the compressor is heated and evaporated in the evaporation section of the first container 1 of the absorption heat pump by heated waste water, which is a low heat source, and the heat of the vapor is absorbed in the absorption section of the same container. The temperature of the refrigerant vapor can be raised to an intermediate temperature higher than that of the heated waste water of a low heat source. Therefore, the temperature difference between the required high temperature of the load fluid flowing through the condenser of the compression heat pump can be small, and in other words, the temperature rise range in the compressor of the compression heat pump can be reduced. This makes it possible to improve the coefficient of performance of the heat pump.

Absorption heat pumps have the function of supplying heat to the refrigerant evaporator of a compression heat pump to raise the temperature of the refrigerant vapor sucked into the compressor, and the absorption heat pump itself performs cooling. Since it does not perform any functions such as heating, it can sufficiently perform its functions even with a low heat source such as relatively low-temperature heated waste water. Therefore, unlike the prior art, the present invention does not require a high-temperature heat source such as steam, but effectively utilizes an easily available low-temperature heat source to operate a heat pump in a practical and efficient manner. It has the characteristic that it can be generated.

[Brief explanation of the drawing]

Figure 1 is a flow sheet diagram of one device for carrying out the method of the present invention, Figure 2 is a performance curve diagram of a compression type heat pump using a screw compressor, and Figure 3 is an absorption type heat pump using a lithium bromide aqueous solution. It is a theoretical plate number characteristic diagram of a heat pump. 1... First container, 2... Evaporation section, 3... Absorption section, 4... Second container, 5... Generation section, 6... Condensation section, 7... Compressor, 8... Condenser. 11...Evaporator.

Claims (1)

[Claims] 1 Concentrate the dilute solution using a low heat source with a temperature higher than that of the cooling water in the generation section of the second container of the absorption heat pump, and transfer the generated vapor refrigerant to the second container.
The liquid refrigerant is cooled and condensed by the cooling water in the condensing part of the container, and this liquid refrigerant is introduced into the evaporation part of the first container of the absorption heat pump and evaporated by the low heat source, and this vapor refrigerant is transferred to the absorption part of the first container. As a result of the absorption, the diluted solution is introduced into the generation section, and the heat obtained in the evaporation section and the absorption heat obtained during the absorption are used to absorb the concentrated solution introduced from the generation section. Utilizes a heat pump that uses medium temperature as a heat source to evaporate the refrigerant liquid of the compression type heat pump, compresses this refrigerant vapor, and then leads it to a condenser where it is condensed and liquefied to obtain the required high temperature. High temperature generation method.