JPS60200064A - Method of utilizing waste heat energy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering low-temperature waste heat (approximately 100° C. or less) and utilizing it as high-temperature thermal energy.

With the progress of energy saving technology, the utilization of high temperature waste heat has progressed), and as a result, a large amount of low temperature waste heat is being emitted from factories and equipment. Because the amount of heat fluctuates irregularly and the exhaust heat source is dispersed in various places, it is regarded as low-level thermal energy with little industrial value and is simply discarded. . If even such low-level waste heat could be recovered and used as high-temperature thermal energy in a concentrated manner, it would be extremely beneficial in terms of energy conservation and improve the economic efficiency of the production process.

There are various methods of recovering waste heat energy and storing it, but the method of storing heat energy as chemical energy by using chemical reactions has the following characteristics, so it is not suitable for low-level emissions as mentioned above. Suitable for heat recovery and use.

(1) Higher heat storage density than other methods.

(2) Since energy does not dissipate during storage, long-term heat storage is possible at room temperature.

(3) When using [2. It is easy to control the quality and quantity of supplied thermal energy.

However, chemical reactions suitable for recovering and utilizing thermal energy have a large zero reaction heat, and ■ the reaction is reversible.
The reaction rate is fast in both directions, ■ the reaction is easy to control, ■ the materials handled are inexpensive, and ■ the materials are non-toxic or have low toxicity. Due to various limitations such as ease of use (storability, transportability, corrosiveness, explosiveness, etc.), systems that utilize the reaction between lithium bromide and water are known to be in practical use. There are only Furthermore, since lithium bromide is expensive, it is not suitable for large-scale use, and its use is limited to small refrigerators, small heaters, and the like.

The present invention provides a method for recovering and utilizing low-level waste heat that fluctuates irregularly and is emitted using a chemical heat storage material. (1) A slurry containing magnesium chloride as a reactant and methanol as a working medium. The liquid is brought into contact with a waste heat source (temperature Tm) at low pressure or normal pressure, and thermal energy is absorbed as the energy necessary for evaporation of methanol.
) to separate the working medium methanol.

MgO12・n 0HaOH(El) −+MgO/2
(n-m) OH80H (S) 10 (dilute slurry liquid)
(Concentrated slurry liquid) me OH (g) (1) where n and m: positive integer, n > mm0% OH (
g) -+ mOH, 10H (1) (2) (releases heat into the ambient air) (2) Heat is stored by separating and storing the concentrated magnesium chloride-methanol slurry and methanol.

(3) Mix a concentrated slurry of magnesium chloride-methanol and methanol at normal pressure or high pressure at a temperature of TM to regenerate the low concentration slurry, and use the heat of dilution generated to create a high-temperature heat medium. Recover and use energy.

This is a method of utilizing waste heat energy consisting of:

Although the operation (1) may be carried out under normal pressure, it is preferably carried out at low pressure in order to efficiently recover waste heat and perform evaporative separation of methanol even at low temperatures. The operation (2) is performed by storing the separated methanol and concentrated slurry liquid, and allows stable heat storage for a long period of time. Operation (3) is carried out via a pump at high pressure (preferably about 10 atmospheres or less).
By doing so, it is possible to prevent methanol from vaporizing at high pressure and make it a stable liquid heat medium at high temperatures. Methanol remains liquid up to about -100°C, and can also be used at temperatures below zero. On the other hand, it is suitable for use at temperatures below about 200°C due to the vapor pressure of methanol.

The mixing ratio of magnesium chloride and methanol is preferably about 1:2.5 or more in molar ratio because methanol also serves as a carrier for solid magnesium chloride, but the upper limit depends on pump power, saturation value of heat of dilution, etc. From this perspective, it is desirable that the molar ratio is 1:20 or less.

This will be explained below using examples.

Example Magnesium chloride was poured into methanol and its calorific value was measured, and the results shown in Table 1 were obtained.

Table 1 Reaction heat of magnesium chloride-methanol system Among these mixtures, those with a mixing ratio of 1:20 and those with a mixing ratio of 1:2
．． When distilled to a concentration of 5, it was possible to separate pure methanol by raising the temperature to a temperature slightly higher than the boiling point of methanol. From these results, for example, a cycle as shown in FIG. 1 can be formed, and low-temperature waste heat can be heated and utilized.

In Fig. 1, a magnesium chloride-methanol mixture (mixing ratio 1:10 mol) is brought into contact with an exhaust heat source at a temperature TM at low pressure or normal pressure, the heat is absorbed, and methanol is evaporated and separated. The methanol is cooled and condensed at the atmosphere (temperature TJ). This methanol is sent via a pump to a storage tank at normal pressure or high pressure and stored. The concentrated magnesium chloride-methanol mixture (mixing ratio 1:2.5) is The methanol and magnesium chloride slurry liquid in the storage tank is sent to a reactor according to demand, where it is mixed and diluted and generated.10 Kcal/-ey・M
The temperature is raised by the heat of gCl2, and the heat is recovered and used by sending it to the radiator as a high-temperature heat medium. After releasing the heat, the magnesium chloride-methanol mixture (mixing ratio 1:10) is sent to the evaporator via vacuum pulp and used again to absorb waste heat.

Although the temperature increase rJj (TH-TM) varies depending on the circulation rate, heat radiation rate, etc., it can be increased to 100° C. or higher if conditions are set so that the heat of dilution is not consumed in vaporization of methanol.

Although this example uses a temperature increase cycle, it goes without saying that this reaction can also be used in a heat increase cycle, a cooling cycle, and a heat storage cycle.

As described above, the present invention is industrially very useful because thermal energy that is irregularly discharged at low temperatures can be recovered, heated, and utilized.

4. Explanation of the Drawings FIG. 1 shows a principle diagram of a temperature raising cycle using waste heat energy according to the present invention.

Among the sub-agents: 1) Akira Sub-agent Ryo Hagi Hara -

Claims (1)

[Claims] When recovering thermal energy from a waste heat source containing low-temperature heat as a high-temperature heat medium, (1) bringing the low-temperature waste heat source into contact with a low-concentration magnesium chloride-methanol mixture; It absorbs thermal energy as the heat required to vaporize and separate methanol. (2) Heat is stored by separately storing the concentrated magnesium chloride-methanol mixture and methanol. (3) A low-strength magnesium chloride-methanol mixture is used as a high-temperature heat medium by mixing a concentrated magnesium chloride-methanol mixture with methanol and using the heat of dilution generated by diluting the magnesium chloride. Play. A method of utilizing waste heat energy characterized by the following.