JPS6112782A - Method for using absorption type heat pump - Google Patents

Abstract

PURPOSE:To improve the heat efficiency and make it possible to operate a heat pump stable for a long period, by using a specific alcohol compound as an absorbent and an amine compound as a solute gas to increase the boiling point difference. CONSTITUTION:(A) A solute of a liquid vapor is adsorbed in (B) an absorent. In the process, the thermal energy generated at the time is utilized to take out heat from an energy source at a low temperature to produce thermal energy at a higher temperature in an absorption type heat pump. In the above-mentioned heat pump, an amine compound is used as the component (A), and an alcohol compound, preferably a polyhydric alcohol compound is used as the component (B). Both components (A) and (B) to be used have >=100 deg.C boiling point difference.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to the thermal energy generated when the vapor of a liquid absorbed by an absorbent (hereinafter referred to as "absorbed material") is absorbed by the absorbent. The present invention relates to a method of using an absorption heat pump, which extracts thermal energy from one or more low-temperature energy sources and generates higher-temperature thermal energy using the heat pump. More specifically, the present invention relates to a combination of an absorbent and an absorbent used in an absorption heat pump.

[Prior art]

Also referred to as the second oil shock, energy sources at higher temperatures, such as heated wastewater and exhaust gas, are used instead of requiring almost any expensive electrical energy.)
Absorption heat pumps have attracted much attention from the viewpoint of effective heat utilization and energy conservation, and various proposals have been made. For example, the water-lithium bromide ammonia aqueous system used as the refrigerant and absorbent combination in absorption chillers can, in principle, be used as the absorbent and absorbent combination in absorption heat pumps by reversing the cycle. It is generally known that it can also be used as However, when applying these systems to an absorption heat pump system, the water-lithium bromide system is particularly prone to corrosion due to the high temperature compared to when used as a refrigerator, and the temperature of the energy source used The temperature difference between the temperature and the temperature of the obtained thermal energy is at most 30 to 40°C, and if you try to obtain a larger temperature difference, there is a danger that solids will precipitate.

Furthermore, the A-Near water system has the disadvantage that the internal pressure of the device is extremely high, so both systems have not yet been put into practical use.

The closest known example to the present invention is Refrigerating Engineering (RE[RIGERA'TING
ENGNEERING>No, 3 (lol, 4B
(1944, 9).

However, this technique has problems in the way the absorbent and absorbent are used, and the difference in boiling points is small, resulting in low thermal efficiency, and when used for a long period of time, scale etc. will deposit, resulting in a decrease in thermal efficiency, which is not desirable.

(Problems to be solved by the invention) In view of these current circumstances, the present inventors have conducted intensive studies with the aim of finding a completely new combination of absorbent and absorbent for an absorption heat pump that does not have the above-mentioned drawbacks. As a result, we have arrived at the present invention.In other words, the present invention uses a specific compound between the absorbent and the absorbent to increase the boiling point difference, improve thermal efficiency, and prevent scale formation even after long-term use. To provide a method for preventing deposition and stably operating a heat pump for a long period of time.

[Means for solving problems]

In order to achieve the above object, the present invention consists of the following configuration.

Alcohol is used as an absorbent in the use of absorption heat pumps, which use the thermal energy generated when liquid vapor is absorbed by an absorbent to extract heat from a low-temperature energy source and produce higher-temperature thermal energy. An absorption heat pump characterized in that an amine compound is used as the absorbent to be absorbed by the absorbent, and the boiling point difference between the alcohol compound and the amine compound is 100°C or more. In the present invention, if the boiling point difference between the absorbent and the absorbent is 100° C. or more, thermal efficiency can be maintained at a high level.

In addition, the combination of the absorbent and the absorbent requires the use of an alcohol compound as the absorbent and an amine compound as the absorbent.

This is because decomposition does not occur even after long-term operation, and scale formation is less likely to occur.

In the present invention, polyhydric alcohols such as diols and triols are preferably used as alcohol compounds. Examples of these compounds include diols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, ,4
-butanediol, hexylene glycol, 1,3-propanediol, 1,5-bentanediol, etc.
Glycerin is a triol. Among these, compounds with alcohol groups at both ends of the carbon chain such as 1.4-butanediol, 1.3-propanediol, and 1.5-bentanediol, ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol. , glycerin is particularly preferred.

The amine compound that is the absorbent may be any of secondary amines, secondary amines, and tertiary amines, including n-propylamine, n-butylamine, isobutylamine 5ec-
Butylamine, tert-butylamine, allylamine, ethylenediamine, propylene diamine, di-n-propylamine, diisopropylamine, diisobutylamine, diethylamine, triethylamine, etc. are used. Among these, primary amines or secondary amines are more preferably used, especially n-propylamine and n-propylamine.
Preference is given to using butylamine, isobutylamine, 5ec-butylamine, tert-butylamine, allylamine, ethylenediamine, propylene diamine, di-n-propylamine, diisopropylamine, diisobutylamine, diethylamine. Further, depending on the method of use, amine compounds can be used as absorbents, and in this case, alkylamines, polyaminos, alkanolamines, polyethyleneimine, etc. are used.

Examples of these compounds include alkylamines such as hebutylamine and octylamine, polyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine, and alkanolamines such as monoethanolamine and octylamine. These include tanolamine, diglycolamine, and aminoethylethanolamine. In this case, the alcohol compound used as the absorbent may be any of primary alcohol, tertiary alcohol, and tertiary alcohol, including methanol, ethanol, n-propanol, isopropanol,
n-butanol, isobutanol, 5ec-butanol, tart-butanol, 3-pentanol, ter
T-amyl alcohol and the like are used.

The absorbent or absorbent may contain substances other than the listed compounds, such as additives that improve the performance of absorption heat pumps, such as absorption promoters, diffusion promoters, and diluents. It is also preferable to add Furthermore, when separating the mixture of the absorbent and absorbent after the absorbent has been absorbed into the absorbent, it is not necessary to completely separate the two; Or, it does not prevent the absorbent from being contained in the absorbent.

An example of a preferred embodiment for efficiently using the absorption heat pump of the present invention is shown as a process diagram in FIG. This will be explained below based on FIG.

The absorbent introduced into the heat recovery device 1 through the liquid feed pipe 7 is evaporated from the absorbed material that enters through the waste feed pipe 11.

By absorbing air, it generates heat and its temperature rises.

The high temperature thermal energy generated here is recovered as recovered heat QH through the tube wall. The absorbent solution that has absorbed the absorbent passes through a liquid feed pipe 8 and a heat exchanger 5, and then is depressurized by a valve 6 and guided to a generator 2. In the generator 2, thermal energy is applied to the absorbent solution from the heat source Q1, and the absorbed agent is dissipated. After dissipating the absorbent, the absorbent is pressurized by the pump 12 and guided to the heat recovery unit 1 via the heat exchanger 5 by the liquid feed pipe 7, where it absorbs the absorbent again and completes the absorbent circulation loop. Form. The absorbent that has been diffused and vaporized by the generator 2 is led to the condenser 3 through the gas pipe 9, where the heat of condensation Q3 is removed by the cooling source and the absorbent is liquefied. The absorbent liquefied in the condenser 3 is pressurized by the pump 10 and then introduced to the evaporator 4. The absorbent 2, which has been given thermal energy from the heat source Q2 in the evaporator 4, is vaporized and introduced into the heat recovery device 1 through the gas pipe 11, where it is absorbed by the absorbent again, resulting in continuous circulation throughout the system. The process is completed. When absorbent enters the absorbent line, vapor containing more absorbent vapor than the liquid composition is always generated due to the vapor-liquid equilibrium relationship in the evaporator 4. The absorbent becomes concentrated. However, as the absorbent is layered, the vapor-liquid equilibrium relationship changes so that the proportion of the absorbent in the vapor generated from the evaporator 4 increases, and finally the evaporator 4
The composition of the liquid entering the evaporator 4 and the vapor exiting the evaporator 4 are equal and a steady state is achieved. Therefore, absorbent is not accumulated in the evaporator 4 indefinitely, and the system can be operated stably.

The method of using the absorption heat pump of the present invention is not limited to the embodiment shown in FIG. It is also preferable to perform heat exchange with the absorbent, and it is also preferable to provide the generator 2 with a distillation column in order to increase the degree of separation between the absorbent and the absorbed material. In the case of the latter embodiment, the format of the distillation column is a packed column,
It may be a bubble bell tower, a tray tower, a perforated plate tower, etc.

Furthermore, the types of the heat recovery device, generator, condenser, evaporator, and heat exchanger are not particularly limited, and types commonly used in absorption refrigerators can also be used.

The energy source used in the method of the present invention may be a liquid heat source such as heated waste water, a gaseous heat source such as waste gas, or a condensable heat source such as waste steam. It goes without saying that this does not preclude the use of means such as electric heating.

The absorption heat pump system according to the present invention can be applied to various processes and unit operations that are widely used in industry. That is, a heating process and a cooling or heat dissipation process at a lower or the same temperature as the heating process, such as distillation columns, multi-effect evaporators, evaporative crystallization, absorption-heat dissipation, adsorption-thermal desorption, absorption-dehumidification, etc. and the temperature difference between the two steps is less than or equal to the temperature difference between the heat source and the heat that can be recovered in the absorption heat pump system according to the invention, the heat obtained in the cooling or heat dissipation step The absorption heat pump according to the present invention is operated using energy as a heat source to supply part of the thermal energy required for the heating process. Furthermore, it is of course possible to use the high-temperature thermal energy obtained by the absorption heat pump according to the present invention as a heat source using the thermal energy obtained in the cooling or heat dissipation process for purposes other than this process.

The combination of absorbent and absorbent provided by the invention can also be used as a heat storage material. Then, thermal energy is applied to the absorbent solution that has absorbed the absorbent to separate it into the absorbent and the absorbent.

Since thermal energy is stored unless the separated two are brought into contact, the thermal energy can be extracted when necessary by absorbing the absorbent into the absorbent.

Since the state from which the thermal energy key is taken out is the same as the initial state in the above procedure, the combination of the absorbent and absorbed material of the present invention can be used repeatedly as a heat storage material. In addition, when extracting thermal energy, instead of absorbing the absorbent as vapor into the absorbent, the two are mixed in a liquid state and only the mixing heat obtained during mixing is recovered as thermal energy. You can also do that. In the latter case, part of the thermal energy required to separate the absorbent from the absorbed material is wasted outside the system as condensation heat of the absorbed material, but this thermal energy can be used to absorb It is also preferable to operate a heat pump or an absorption refrigerator.

It goes without saying that the combination of absorbent and absorbent provided by the present invention can be used as a combination of absorbent and refrigerant for an absorption refrigerator. In that case, in the water-lithium bromide system, it is not possible to obtain cold temperatures below O'C, whereas with the combination of the absorbent and absorbent provided by the -C1 present invention, operation at temperatures below 0C is possible.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 A small glass bench apparatus having the components shown in FIG. 1 was prepared, and heat recovery experiments were conducted on various combinations of absorbent and absorbent under the following conditions.

Experimental conditions Generator temperature 100℃ Condenser temperature
30℃ evaporator temperature 100
The results obtained are shown in Table 1 below.

In Table 1, all of them had high thermal efficiency and were able to maintain high recovered heat, which was preferable.

Furthermore, when the combination of absorbent and absorbent was as shown in the table above, no scale was observed in the system even after long-term use, and stable operation was possible.

Comparative Example 1 A heat recovery experiment was conducted under the same conditions as in Example using diethylenetriamine as an absorbent and ethanol as an absorbent.

As a result, the absorbent changed color to a brownish color halfway through use, and
After a month, scale deposits were observed within the system. This scale lowered the thermal conductivity coefficient, worsened thermal efficiency, and also caused clogging of piping, causing serious problems in maintaining the system's operation.

Comparative Example 2 A publicly known example, REFRIGERATING ENGINEERIN
G) N, 3Vo1.48 (1944, 9) 2nd
Experiments were conducted in the same manner as in the examples, using ethylene glycol as the absorbent and ethylene diamine as the absorbent, which are listed in the 64th position from the top of Table 6 on page 04.

As a result, the temperature of the heat recovery device only rose to 130℃,
Thermal efficiency was not favorable.

〔Effect of the invention〕

The features of the method of the present invention are as follows in comparison with already known absorption heat pump systems.

(1) Less corrosive.

Since the absorbent and absorbent of the present invention are both low-corrosive compounds, there is little fear of corrosion in the high-temperature range, which is a problem in water-lithium bromide systems. In particular, when operating an absorption heat pump using waste heat from other processes as a heat source, there are often restrictions on equipment materials depending on the type of waste heat, but the absorbent and absorbed material system of the present invention There are few restrictions on the materials used, so there is a possibility that various types of waste heat can be used as a heat source.

(2) There is no need to worry about solid precipitation.

All the absorbents and absorbents provided by the present invention exist as liquids in the normal operating temperature range of absorption heat pumps, and there is no risk of solid precipitation as is the case with water-lidium bromide systems. There is no gender. Therefore, there is no need to worry about excessive concentration, and the system can be easily controlled.

(3) The internal pressure of the device does not become too high.

When an ammonia-water system is applied to an absorption heat pump, the high vapor pressure of ammonia creates extremely high pressure inside the device, resulting in an increase in the size of the device. Since the pressure is not so high, the entire device can be made more compact compared to an ammonia-water system.

(4) High-temperature thermal energy can be recovered.

In the combination of absorbent and absorbent provided by the present invention, by increasing the concentration of the absorbent in the generator, it is possible to obtain thermal energy at a temperature even higher than that which can be reached with the water-lithium bromide system. can. This is the second
As mentioned in section 1, the water-lithium bromide system has a solubility limit and cannot increase the concentration above a certain value, whereas the absorbent and absorbent system of the present invention overcomes such a limit. This is because there is no one.

(5) The boiling point difference between the absorbent and the absorbed material is increased to improve thermal efficiency, and even after long-term use, the heat pump can be operated stably for a long period of time by preventing the deposition of scale and the like.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing one embodiment of the absorption heat pump of the present invention. 1: Heat recovery device, 2: Generator, 3: Condenser,
4: Evaporator, 5: Heat exchanger, 10, 12:
pump.

Claims (2)

[Claims] (1) In the method of using an absorption heat pump, which uses the thermal energy generated when liquid vapor is absorbed by an absorbent to extract heat from a low-temperature energy source and generate higher-temperature thermal energy, the absorbent An absorption method characterized in that an alcohol compound is used as the absorbent, an amine compound is used as the absorbent to be absorbed by the absorbent, and the boiling point difference between the alcohol compound and the amine compound is 100°C or more. How to use a heat pump. (2) A method of using an absorption heat pump according to claim (1), wherein the alcohol compound is a polyhydric alcohol compound.