JPH10205308A - Mixed medium cycle power generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain higher output and efficiency than those expected on conventional systems in a mixed medium cycle power generating system which employs a non-azeotropic mixed medium made of low-boiling and high-boiling media and where the temperature and the amount of a heat source are specified. SOLUTION: An evaporator 1 which evaporates a part of a mixed medium and creates the two-phase condition of vapor and liquid by means of a heat exchange with the heat source of a rather lower temperature, a first separator 2a which separates the two-phase medium into vapor and liquid, a turbine 3 which is supplied with the vapor medium separated by the first separator 2a, a condenser 4 which condenses the exhaust gases from the turbine 3 into liquid and feeds it back to the evaporator 1, a second separator 2b which separates the two-phase medium left after the first separator 2a into vapor and liquid again, a line 9 which introduces the vapor-phase medium left after the second separator 2b to the interstage of the turbine 3 and a line 10 which allows the liquid-phase medium left after the second separator 2b to be used to heat the liquid-phase medium at the inlet of the evaporator 1 then to contact and mix with the exhaust from the turbine 3, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed-medium cycle power generation system using a non-azeotropic mixed medium consisting of a low-boiling medium and a high-boiling medium as a working medium.

[0002]

2. Description of the Related Art Conventionally, in a power generation system using a heat source having a relatively low temperature, a non-azeotropic mixture medium composed of a low-boiling medium and a high-boiling medium has been used as a working medium.

That is, FIG. 5 shows that ammonia is used as a low-boiling-point medium component, water is used as a high-boiling-point medium, and a temperature of 150.degree.
FIG. 1 is a system diagram of a non-azeotropic mixed-medium cycle power generation system using a heat source of not more than 1 ° C., wherein the medium comprising ammonia and water is supplied to an evaporator 1, where it is heated and partially evaporated, and ammonia is passed through a separator 2. Is separated into a dense gas phase and a lean liquid phase.

[0004] The gas phase medium separated by the separator 2 is guided to a turbine 3, where it is worked, and then introduced into a condenser 4.

On the other hand, the liquid-phase medium separated by the separator 2 emits heat in the regenerator 5 and is decompressed by the decompressor 6.
It is led to the condenser 4. In the condenser 4, the medium after performing the work in the turbine 3 and the medium depressurized by the decompressor 6 are mixed in contact. Then, the mixed medium returns to the concentration before the evaporation, is cooled and condensed by the condenser 4, is pressurized by the medium circulation pump 7 and enters the regenerator 5, where the liquid phase separated by the separator 2 is separated. After being heated by the medium, it is returned to the steamer 1.

[0006]

By the way, in the system shown in FIG. 5, the heat exchange close to the Lorentz cycle along the heat source temperature change is caused by the non-isothermal evaporation characteristic of the non-azeotropic mixed medium in the evaporator. It is possible, and a cycle with high exergy efficiency can be realized.

FIG. 6 shows 98 ° C. using ammonia / water as a medium.
FIG. 4 is a diagram showing a part of the heat balance of the conventional method cycle when the heat source is used. In the regenerator shown in FIG. 5, for the liquid phase medium whose energy state has been raised to the high temperature and high pressure region by the evaporator 1, only the heat use of heating the liquid phase medium in front of the evaporator inlet is used. is not.

When the gas phase and the liquid phase of the mixed medium are mixed, the concentration of the low-boiling-point medium component of the liquid-phase medium (or ammonia in the case of a water / ammonia mixed medium) is determined by the concentration of the low-boiling-point medium component of the gas-phase medium. When the temperature is lower and the temperature of the liquid-phase medium is lower than the temperature of the gas-phase medium, a phenomenon occurs in which the gas-phase medium is absorbed by the liquid-phase medium and the whole becomes a liquid phase. This phenomenon is more likely to occur as the difference between the vapor concentration and the temperature is larger.
It is desirable to positively utilize this phenomenon of absorption in the condenser of the mixed medium cycle.

However, the temperature (40.4 ° C.) of the liquid phase medium at point A where the liquid phase medium separated by the separator 2 in FIG. 22.6 ° C), the point B was added to the thin ammonia liquid medium at point A.
There is a risk that the medium having a high ammonia concentration will not be absorbed and the medium will not be sufficiently liquefied in the condenser 4 which is a heat exchanger. If the complete liquefaction of the medium in the condenser 4 is not performed, thick ammonia vapor remains in the condenser 4 and the turbine exhaust pressure increases, making it difficult to realize the heat balance shown in FIG. As a result, the turbine output may be significantly reduced.

In view of the foregoing, it is an object of the present invention to provide a system capable of improving output and efficiency as compared with a conventional system when a heat source temperature and a heat source amount are specified.

[0011]

A first aspect of the present invention is a non-azeotropic mixed medium cycle power generation system using a non-azeotropic mixed medium consisting of a low-boiling medium and a high-boiling medium as a working medium. An evaporator that evaporates a part of the non-azeotropic mixed medium into a gas-liquid two-phase state by heat exchange with a first separator that gas-liquid separates the medium in the gas-liquid two-phase state; A turbine to which the gaseous phase medium separated by the first separator is supplied, a condensate for condensing exhaust gas from the turbine and returning the exhaust gas to the evaporator, and a two-phase state after the first separator A second separator for gas-liquid separation of the medium again, a system for guiding the gas phase medium after the second separator to an intermediate stage of the turbine, and a liquid phase medium after the second separator at an evaporator inlet. A system for contacting and mixing with exhaust gas from the turbine after using it for heating the liquid medium. That.

According to a second aspect, in the first aspect, the second aspect is provided.
The gaseous medium after the separator is supplied to another turbine instead of the middle stage of the turbine to which the gaseous medium after the first gas-liquid separation is supplied.

A third invention is characterized in that, in the first or second invention, means for heating the gas phase side of the second separator by using heat from a heat source or a medium in the cycle is provided.

According to a fourth aspect, in the first aspect, the second aspect is provided.
Wherein the gas phase medium after the separator is replaced with an intermediate stage of a turbine to which the gas phase medium after the first gas-liquid separation is supplied, and is contact-mixed with the working medium in a second high-pressure condenser. .

A fifth invention is characterized in that in each of the above inventions, the relatively low-temperature heat source is a heat source of 150 ° C. or less.

A sixth invention is characterized in that, in each of the above inventions, the heat source is geothermal heat, solar hot water, or plant exhaust heat.

According to a seventh aspect of the present invention, in each of the above inventions, the first aspect is provided.
In the working medium of the system connected from the separator to the second separator and further to the condenser, an additive for uniformly mixing the low-boiling-point medium-dilute solution and the turbine exhaust is added. .

According to an eighth aspect of the present invention, in each of the above aspects, the working medium at the inlet of the evaporator includes a medium having a boiling point increasing effect in order to increase exergy efficiency and increase work in the turbine by increasing the temperature during medium evaporation. It is characterized by being thrown.

In a ninth aspect of the present invention, in each of the above-mentioned aspects, when the working medium is a mixed medium of ammonia and water and a heat source at about 90 ° C. to 200 ° C. is used, 0.7 to 0.95 mol / mo is used.
l is the concentration ratio of the ammonia concentration.

[0020]

Embodiments of the present invention will be described below with reference to FIG. In the drawing, the same parts as those in FIG. 5 are denoted by the same reference numerals.

The mixed medium of ammonia and water is heated by the heat exchange with a relatively low-temperature heat source of about 150 ° C. or less, such as geothermal heat, solar hot water, or plant exhaust heat, in the evaporator 1 to partially evaporate. In the first separator 2a, a gas phase in which ammonia is rich and a liquid phase in which ammonia is diluted are separated. The gas-phase medium separated by the first separator 2a is supplied to the turbine 3
After performing work there, the liquid is condensed by the liquid condensing device 4, then pressurized by the medium circulation pump 7 and returned to the evaporator 1 via the regenerator 5.

On the other hand, the liquid phase portion of the first separator 2a is connected to the second separator 2b via a pressure reducer 6a by a conduit 8, and the gas phase portion of the second separator 2b is It is connected via a conduit 9 to an intermediate stage of the turbine 3. Therefore, the liquid phase medium separated by the first separator 2a is supplied to the decompressor 6
The pressure is reduced at a, and the gas is introduced into the second separator 2 b, where the gas-phase medium further separated by gas-liquid separation is mixed into an intermediate stage of the turbine 3.

The gas phase medium that has performed work in the turbine 3 is condensed in the condenser 4 and returned to the evaporator 1 by the absorption circulation pump 7.

The liquid phase medium separated by the second separator 2b passes through the regenerator 5 and is depressurized by the pressure reducer 6b through the conduit 10 and is contact-mixed with the gas phase medium at the outlet of the turbine 3 in the condenser 4 Is done.

FIG. 2 shows the system shown in FIG.
FIG. 7 is a diagram showing an example of a heat balance when the heat source temperature is 98 ° C. and the amount of heat exchanged by the evaporator is 35855 kW, which is the same as that of the system shown in FIG. Here, it is assumed that the turbine efficiency is 0.85 and the generator efficiency is 0.95. Further, the liquid phase medium separated by the second separator 2b is
The temperature of the liquid medium at point A (20 ° C.) introduced into the turbine is lower than the temperature of point B of the turbine exhaust steam (22.7 ° C.), and the ammonia concentration of the liquid medium at point A (0.673 mol / mol) is lower than the ammonia concentration (0.711 mol / mol) of the conventional cycle shown in FIG. 6, sufficient mixing and liquefaction are performed in the condenser 4, and a decrease in turbine output due to an increase in turbine exhaust pressure is also prevented. Can be.

FIG. 3 is a view showing another embodiment of the present invention, in which a gas phase medium after gas-liquid separation by a second separator 2b is a second turbine separate from the first turbine 3a. The gaseous medium introduced into 3b and working there is likewise merged with the gaseous medium after working in the first turbine 3a via the conduit 11 in front of the condenser 4. . Therefore, the same effect as that of the invention shown in FIG. 1 can be obtained.

In the embodiment shown in FIGS. 1 and 3, after the gas phase medium separated by the second separator 2b is appropriately heated by using heat from a heat source or a medium in a cycle, the turbine 3 or 3b.

FIG. 4 is a view showing still another embodiment of the present invention, in which a gas-phase medium after gas-liquid separation by a second separator 2b is passed through a conduit 12 to a first medium circulation pump 7a. The second liquid condensing device 4b is contact-mixed with the liquid phase medium pressurized in the second condensing device 4b, and the liquid medium after the second condensing device 4b is heated to the medium evaporation pressure by the second medium circulation pump 7b. It is boosted. Thus, in this case, the temperature (22.5 ° C.) of the liquid phase medium at the point A where the liquid medium from the second separator 2b is introduced into the first condenser 4a is set at the point B of the turbine exhaust steam. Since the ammonia concentration (0.636 mol / mol) on the absorption liquid side is lower than the ammonia concentration (0.711 mol / mol) in the conventional cycle shown in FIG. Thorough mixing and liquefaction of
A decrease in turbine output can be prevented.

In FIGS. 1, 3 and 4, addition is made to the liquid system including the first separator 2a and the second separator 2b so that the liquid film interface facilitates substance diffusion by interfacial disturbance. Agent,
For example, in the case of a water / lithium bromide mixed medium, n
-By injecting and circulating octanol and the like, contact mixing with turbine exhaust can be facilitated and cycle efficiency can be improved.

Further, in FIG. 1, FIG. 3, and FIG.
Into a liquid system including the separator 2a and the second separator 2b, a medium having a boiling point increasing effect, such as salts, is added to increase the pressure at the time of evaporating the medium to increase the work in the turbine; The output of the medium having the boiling point increasing effect can be further improved by using the medium in an area where evaporation is not performed.

In the above embodiment, the medium is composed of two components, water and ammonia. However, the medium may be composed of three or more components such as water, ammonia and lithium bromide. 90 for medium
An ammonia concentration of 0.7 to 0.95 mol / mol with a heat source of about 200C to 200C is preferred.

[0032]

As described above, according to the present invention, the liquid phase medium sequentially separated by the first separator and the second separator is brought into contact with and mixed with the turbine exhaust gas. The high-concentration gas-phase medium is effectively absorbed, and not only can the turbine exhaust pressure be reduced to increase the turbine work, but also the turbine exhaust can be completely condensed.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of a non-azeotropic mixed medium cycle power generation system of the present invention.

FIG. 2 is a diagram showing an example of a heat balance of the system shown in FIG. 1;

FIG. 3 is a diagram showing an example of another embodiment of the present invention.

FIG. 4 is a system diagram showing an example of a heat balance according to still another embodiment of the present invention.

FIG. 5 is a system diagram showing another example of a conventional non-azeotropic mixed medium cycle power generation system.

6 is a diagram showing an example of a heat balance of the system shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporator 2 Separator 2a 1st separator 2b 2nd separator 3 Turbine 3a 1st turbine 3b 2nd turbine 4 Condenser 4a 1st condenser 4b 2nd condenser 5 Regeneration Device 6 Pressure reducer 6a First pressure reducer 6b Second pressure reducer 7 Medium circulation pump 7a First medium circulation pump 7b Second medium circulation pump

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masakuni Sasaki 1-1-1, Shibaura, Minato-ku, Tokyo Inside Toshiba Corporation Head Office (72) Inventor Mikio Takayanagi 1-1-1, Shibaura, Minato-ku, Tokyo No. 1 Toshiba Corporation head office

Claims (9)

[Claims] In a mixed-medium cycle power generation system using a non-azeotropic mixed medium composed of a low-boiling medium and a high-boiling medium as a working medium, a part of the mixed medium is evaporated by heat exchange with a relatively low-temperature heat source. An evaporator that is brought into a gas-liquid two-phase state, a first separator that gas-liquid separates the medium in the gas-liquid two-phase state, and a gas-phase medium separated by the first separator are supplied. A turbine, a condensate for condensing exhaust gas from the turbine and refluxing the gas to the evaporator, a second separator for gas-liquid separation of the two-phase medium after the first separator, and a second separator.
A system for guiding the gaseous medium after the separator to the middle stage of the turbine, and contact mixing with exhaust gas from the turbine after using the liquid medium after the second separator for heating the liquid medium at the inlet of the evaporator. A mixed medium cycle power generation system, comprising: 2. The method according to claim 1, wherein the gaseous phase medium after the second separator is supplied to another turbine in place of a turbine to which the gaseous phase medium after the first gas-liquid separation is supplied. Item 7. A mixed medium cycle power generation system according to Item 1. 3. The mixed medium cycle power generation system according to claim 1, further comprising means for heating the gas phase side of the second separator using a heat source or heat from a medium in the cycle. 4. The method according to claim 1, wherein the gaseous medium after the second separator is replaced with an intermediate stage of a turbine to which the gaseous medium after the first gas-liquid separation is supplied. The mixed medium cycle power generation system according to claim 1, wherein the mixed medium cycle power generation is performed. 5. The mixed medium cycle power generation system according to claim 1, wherein the relatively low-temperature heat source is a heat source of 150 ° C. or less. 6. The mixed medium cycle power generation system according to claim 1, wherein the heat source is geothermal heat, solar hot water, or plant exhaust heat. 7. An additive for uniformly mixing a solution having a low boiling point medium and a turbine exhaust gas is added to a working medium of a system connected from the first separator to the second separator and further to the condenser. The mixed medium cycle power generation system according to any one of claims 1 to 6, wherein: 8. A working medium at the inlet of the evaporator is charged with a medium having a boiling point increasing effect in order to increase exergy efficiency and increase work in a turbine by raising the temperature to a high temperature during medium evaporation. The mixed medium cycle power generation system according to claim 1. 9. The working medium is an ammonia / water mixed medium.
When a heat source of about 0 ° C to 200 ° C is used, 0.7
The mixed medium cycle power generation system according to any one of claims 1 to 8, wherein a concentration ratio of the ammonia concentration is from 0.95 mol / mol to 0.95 mol / mol.