JPS6210347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of converting relatively low-temperature energy to relatively high-temperature energy, and particularly relates to an effective energy conversion method between energies with low temperature differences.

Methods for recovering low-temperature level thermal energy and converting it into high-temperature energy include (1) using a compression heat pump that compresses using external power and uses pressure difference energy, and (2) without using external power. There is a method of converting the heat medium into concentration difference energy by evaporating or distilling and concentrating the heat medium using low-temperature level thermal energy, and then raising the temperature to a high temperature by diluting and concentrating the heat medium.

In addition, method (2) includes (a) a method that mixes multiple heat media and uses the heat of dilution, heat of fusion, and heat of reaction generated at that time, and (b) a method that further applies an absorption refrigeration cycle. There is also a method that utilizes the latent heat of phase change.
Compared to the former method (a), the latter method (b) uses phase change latent heat, so it has a lower thermal efficiency (ratio of heat output to heat input).
is very large. However, the latter method (b) has the fundamental drawback that because it utilizes phase change, the maximum temperature that can be raised is controlled by the vapor pressure within the system, and the temperature of the energy that can be obtained is limited.

The conventional energy conversion method will be explained below using (2)-(b) conversion method using dilution heat and latent heat of phase change. FIG. 1 is a conventional thermal energy conversion cycle diagram, and FIG. 2 is a PT diagram showing the relationship between vapor pressure (P) and temperature (T) in the cycle shown in FIG. 1.

This cycle consists of a concentration section 1 that concentrates a high boiling point liquid 3;
1, a condensing section 12 that condenses and recovers the low boiling point vapor 2A separated there, an evaporating section 13 that evaporates the low boiling point liquid 2, and the low boiling point vapor 2A generated here is absorbed into the high boiling point liquid 1. and an absorption/heat generation section 14 that generates heat and raises the temperature. In this cycle, like the absorption refrigeration cycle, a high boiling point liquid (for example, LiCl liquid) 1 and a low boiling point liquid (for example, H ₂ O) 2 are used as heat carriers.

The symbols AF shown in FIGS. 1 and 2 are common, and the state of the relationship between vapor pressure and temperature at AF in the process of FIG. 1 is shown in FIG. First, absorption heat generation part 1
4, the low boiling point liquid 3 (high boiling point liquid concentration C ₁ %) which has been diluted by absorbing the low boiling point vapor 2 flows into the concentrating section 11 at the system pressure P ₁ and temperature T ₂ (A). In the concentrating section 11, the low boiling point liquid receives relatively low-temperature energy 21.
is heated and evaporated to generate 2A of low boiling point vapor (high boiling point liquid concentration: 0%). As a result, the low boiling point liquid is separated from the high boiling point liquid 3, and the high boiling point liquid 3 is concentrated to become a high concentration liquid (high boiling point liquid concentration C ₂ %) 1.
(B), return to the lower absorption/heat generation section 14 (C). On the other hand, the generated low-boiling point liquid vapor 2A is cooled and condensed by relatively low-temperature energy 22 in the condensing section 12, where the pressure is almost the same as that of the concentrating section 11 and the temperature T ₁ (<T ₂ ), and becomes the low-boiling point liquid 2 ( E), enters the lower evaporation section 13
(F). The evaporator 13 is in a state of a pressure P ₂ (>P ₁ ) and a temperature T ₂ , and the low boiling point liquid 2 flowing therein is heated by the low temperature energy 21 and evaporated. The low boiling point vapor 2A generated therein is absorbed into the concentrated high boiling point liquid 1 from the concentrating section 11 in the absorption heat generating section 14 having the same pressure as the evaporating section 13. The high boiling point liquid 1 is further diluted to become a diluted high boiling point liquid 3 (D) with a concentration of C ₁ %, and heat is generated due to the heat of dilution of the high boiling point liquid 1 and the phase change latent heat due to absorption and liquefaction of the low boiling point vapor 2A. C ₁ %
The temperature is raised to the saturation temperature T at the vapor pressure _P2 . As a result, heat is absorbed from low temperature energy 21 at temperature T ₂ (A → B, F), and low temperature energy 2 is absorbed at temperature T ₁ .
By releasing heat (E) to 2, relatively high temperature energy 23 having a temperature T higher than T ₁ and T ₂ can be obtained (C→D). In the above cycle, in order to simplify the explanation, high boiling point liquid 1, low boiling point liquid 2
The temperature difference due to heat transfer to is ignored. (Actually, there is a difference of 2 to 3 degrees Celsius between the two due to thermal resistance.) As described above, this cycle has high thermal efficiency because it can utilize the dilution heat of the high boiling point liquid 1 and the phase change latent heat of the low boiling point steam 2A. On the other hand, as shown at position D in FIG. 2, the maximum temperature increase T is limited by the high boiling point liquid concentration C ₁ % and the pressure P ₂ at that time. Therefore, when the temperature of the relatively low-temperature energy is low (T ₁ , T ₂ ) and the temperature difference ΔT (T ₂ - T ₁ ) between the two is small, the pressure P ₂ is also small and the concentration C ₁ is also low. Therefore, there is a drawback that the maximum temperature rise T becomes low.

In addition, as shown in Figure 3, the dilution concentration range (C ₂
−C ₁ ) is wide, and the heat of dilution increases exponentially as the concentration of the high-boiling point liquid increases. However, in the conventional cycle shown in FIG. 2, there is a limit to increasing the heat of dilution due to such drawbacks.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, increase the dilution heat of low-temperature energy, and
The purpose is to provide a method that can convert energy into higher temperature energy.

The present invention makes it possible to concentrate a high-boiling point liquid under low pressure and dilute the concentrated high-boiling point liquid under high pressure by using an intermediate liquid having certain characteristics. . That is, the present invention uses, as an intermediate liquid, a medium in which the difference between its saturation temperature and the saturation temperature of the high-boiling point liquid is small under low pressure, and the difference in saturation temperature between the two becomes large under high pressure. The above object is achieved by providing a dilution/concentration process for the medium solution.

Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 4 is a cycle diagram showing an example of the present invention, and FIG. 5 is a PT diagram showing the relationship between vapor pressure (P) and temperature (T) in the cycle shown in FIG. 4. The cycle shown in FIG. 4 differs from the cycle shown in FIG. 1 in that the condensing section 1 in FIG.
2. An intermediate absorption section 12A and an intermediate evaporation section 13A are provided in place of the evaporation section 13, and a line for circulating the intermediate medium liquid is provided between these sections.

In the present invention, the intermediate medium liquid is P-T which indicates the relationship between vapor pressure (P) and temperature (T) during this cycle.
The PT line in the diagram has a characteristic of having a larger slope than the PT line of the high boiling point liquid in this PT diagram.

In FIG. 4, the dilute high boiling point liquid 3
(indicated by position code A in Figs. 4 and 5. Hereinafter, only the code will be shown), where the pressure
Under the condition of P ₁ ′ (<P ₁ ) and temperature T _2, low-temperature energy 2
1, a low-boiling liquid vapor 2A is generated, and the high-boiling liquid is concentrated to a concentration of C ₄ % (>C ₂ %) (B). The low boiling point liquid vapor 2A generated in the concentration section 11 is introduced into the intermediate absorption section 12A at a temperature T1 under the same pressure as the concentration section ₁₁ . Intermediate absorption section 12
A is an intermediate medium liquid 5 (concentration) having the above-mentioned characteristics.
C ₂ '%) is supplied, where the low boiling liquid vapor 2A
is absorbed into the intermediate liquid 5 while being cooled by the low-temperature energy 22. As a result, the intermediate medium liquid 5 is diluted from the concentration C ₂ '% to the concentration C ₁ '% (E).
The diluted intermediate medium liquid 4 flows into the intermediate evaporation section 13A under the condition of pressure P ₂ ′ (P ₁ <P ₂ ′<P ₂ ) (F), where it is heated by low-temperature energy 21 at a temperature E, The low boiling point liquid vapor 2A is separated by evaporation and condensed to a concentration of C ₂ '% (G). The concentrated intermediate medium liquid 5 is again circulated to the intermediate absorption section 12A.

On the other hand, in the concentration section 11, the high boiling point liquid 1 concentrated to a concentration of C ₄ % is introduced into the absorption exothermic section 14,
The vapor 2A of the low boiling point liquid generated in the intermediate evaporation section 13A is absorbed into this concentrated high boiling point liquid 1 and generates heat.
The temperature is raised to a saturation temperature T at a concentration of C ₃ % (>C ₁ %) and a pressure of P ₂ ' (D), and high-temperature energy 23 approximately corresponding to the heating temperature is obtained.

In addition, Fig. 5 shows a P-T diagram (shown by chain lines) showing the relationship between pressure (P ₁ , P ₂ ) and temperature (T ₁ , T ₂ ) at each part in Fig. 1 (conventional example), and this P -The high temperature energy temperature (T') obtained on the T diagram is shown for comparison. Furthermore, Fig. 5 shows the system pressure when a high boiling point liquid is used as the intermediate medium liquid (that is, when the slope of the PT diagram of the intermediate medium liquid matches the PT diagram of the high boiling point liquid). (P ₁ ′, P ₁ ) and the temperature T″ reached by high-temperature energy are shown as reference examples.

According to this embodiment, by adding low-temperature energy (T _{1 ,} T ₂ ) _at the same temperature as in the conventional example shown in FIG.
%) and dilute it, it is possible to obtain higher temperature energy (T>T'). Furthermore, in this example, compared to the reference example in which a high boiling point liquid was used as the intermediate liquid, the absorption/heat generation section 14 can be operated under high pressure (P' ₂ > P ₁ ).
Higher temperature energy (T>T″) can be obtained.

Next, as another embodiment of the present invention, a method of diluting and concentrating the intermediate medium liquid in multiple stages is shown in FIG. 6, and FIG. 7 shows the vapor pressure and temperature at A-J of each step shown in FIG. FIG. 2 is a PT diagram showing the relationship between In FIG. 6, the high-boiling point liquid 3 is heated by low-temperature energy 21 in the concentration section 11 under pressure P ₁ ', and the vapor 2A of the low-boiling point liquid is evaporated and concentrated.
It becomes a high boiling point liquid with a concentration of C ₄ % (B). The low boiling point liquid vapor 2A generated in the concentration section 11 is introduced into the intermediate absorption section 12A at a temperature T1 under the same pressure as the concentration section ₁₁ . The intermediate liquid 5 having a concentration of C ₅ '% is supplied to the intermediate absorption section 12A, where the low boiling point liquid vapor 2A is absorbed into the intermediate liquid 5 while being cooled by the low temperature energy 22. As a result, the intermediate medium liquid 5
is diluted to a concentration of C ₄ '% (H). The diluted intermediate medium liquid 4 flows into the intermediate evaporation section 13A of _P3 under higher pressure (I), where it is heated under the condition of temperature _T2 , and the vapor 2A of the low boiling point liquid is evaporated and separated, and the concentration is reduced. Concentrated to C ₅ ′% (J). The concentrated intermediate medium liquid 5 is again circulated to the intermediate absorption section 12A (G).

On the other hand, the low boiling point liquid vapor 2A evaporated and separated in the intermediate evaporation section 13A is cooled and liquefied in the condensation section 12 at a temperature of _T1 (E), and flows into the evaporation section 13 under the condition of higher pressure _P2 ( F). In the evaporation section 13, the low boiling point liquid is heated under the condition of temperature _T2 to become low boiling point liquid vapor 2A, and enters the absorption exothermic section 14 under the same pressure as the evaporation section 13, where it is converted into high boiling point liquid 1. Absorbed (D). The high boiling point liquid 3 thus diluted to a concentration of C ₃ % is returned to the concentration section 11 (A). In the absorption/heat generation section 14, the temperature is raised to a saturation temperature T at a pressure P ₂ and a concentration C ₃ %, and high temperature energy 23 approximately corresponding to the heating temperature is obtained.

In addition, Fig. 7 shows the pressure in the system when the high boiling point liquid is used as is as the intermediate medium liquid (that is, when the slope of the PT line of the intermediate medium liquid matches the PT line of the high boiling point liquid). The temperature T' reached by high-temperature energy is shown as a reference example.

According to this example, since the high-boiling point liquid can be concentrated under low pressure (P ₁ ′<P ₁ ), a high-concentration high-boiling point liquid (C ₄ %>C ₂ %) can be obtained. Heat generation temperature T
(>T′) is high.

In the present invention, as the intermediate medium liquid, when water is used as the low boiling point liquid, NaOH, (CaCl ₂ + LiCl)
CaCl ₂ , MgBr ₂ and the like can be mentioned, and high boiling point liquids can include MgCl, LiBr, H ₂ SO ₄ , ZnCl ₂ and the like.

Furthermore, if the intermediate liquid is selected to have the property of absorbing heat when absorbing the vapor of the low boiling point liquid, the amount of heat in the intermediate evaporation section and the intermediate absorption section can be reduced, thereby improving thermal efficiency.

As described above, according to the present invention, the high-boiling point liquid in the medium liquid can be concentrated to a high concentration using low-temperature thermal energy, and the concentrated high-boiling point liquid can be diluted under high pressure. can be converted into higher temperature energy.

[Brief explanation of the drawing]

Figure 1 is a conventional thermal energy conversion cycle diagram.
Figure 2 is a P-T diagram for the cycle shown in Figure 1, Figure 3 is a relationship diagram between liquid concentration and dilution heat, and Figure 4 is a diagram showing the relationship between liquid concentration and heat of dilution.
The figure is a cycle diagram showing an example of the present invention, FIG. 5 is a P-T diagram for the cycle shown in FIG. 4, FIG. 6 is a cycle diagram showing another example of the present invention, and FIG. FIG. 3 is a PT diagram in the cycle shown in FIG. 1... High boiling point liquid (concentration), 2A... Steam (low boiling point liquid), 3... High boiling point liquid (dilution), 4... Intermediate medium liquid (dilution), 5... Intermediate medium liquid (concentration), 11... Concentration section, 1
2... Condensation section, 12A... Intermediate absorption section, 13... Evaporation section, 13A... Intermediate evaporation section, 14... Absorption heat generating section, 2
1...Low temperature energy, 22...Low temperature energy, 2
3...High temperature energy (recovered energy).

Claims (1)

[Claims] 1. A concentration step of evaporating and concentrating a medium liquid having components with different boiling points to separate a low-boiling point liquid, and evaporating the low-boiling point liquid, and a high-boiling point liquid obtained by concentrating the vapor of the low-boiling point liquid. In a condensation type thermal energy conversion method, which has an absorption exothermic step in which the energy absorbed and exothermicly supplied into the system is converted into energy at a higher temperature than this energy, the vapor of the low boiling point liquid generated in the concentration step is P-T in a P-T diagram showing the relationship between vapor pressure (P) and temperature (T) inside
The line is P of the high boiling point liquid in this P-T diagram.
-Absorbing into an intermediate medium liquid having characteristics with a larger slope than the T line, evaporating and concentrating the diluted intermediate medium liquid here, and introducing the vapor of the low boiling point liquid separated here into the absorption exothermic process. Features a concentrated thermal energy conversion method. 2. The concentrating thermal energy conversion method according to claim 1, wherein the steps of diluting and concentrating the intermediate medium liquid are performed in multiple stages. 3. The concentrating thermal energy conversion method according to claim 1, wherein the intermediate liquid has a property of exhibiting an endothermic reaction when absorbing the vapor of the low boiling point liquid.