JPS5936083B2 - Power generation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power generation method, primarily in a Rankine cycle engine operating at a low temperature difference.

As is already well known, the Rankine cycle engine uses water, fluorocarbons,
After pressurizing a working medium such as ammonia or butane with a pump, it is heated and evaporated using external heat in an evaporator.
This steam is introduced into an expander such as a turbine type, reciprocating type, or screw set and expanded, and a part of the energy possessed by the steam is extracted outside in the form of power.
- Steam that has been depressurized and cooled by expansion in a power expander is led to a condenser and condensed, and then pressurized again with a pump to repeat the same cycle.

In some Langin cycle engines, saturated steam is generated in an evaporator and is directly fed into the expander, while others are equipped with a superheater after the evaporator to superheat the steam before feeding it into the expander.

Further, in this case, if the steam at the expander outlet is superheated steam, a heat exchanger may be provided to preheat the working medium to be returned to the evaporator with the steam at the expander outlet.

In addition, the high-temperature liquid under pressure is directly guided to the first expander to do work, the generated steam drives the second expander, and the vapor and liquid are separated at the outlet of the first expander and flashed. The generated steam is led to a tank and flashed, the generated steam is led to the intermediate stage of the second expander and combined with the first steam to do work, and the steam exiting the second expander is cooled and condensed. Some systems use a pump to return the liquid to a liquid heater.

In the case of geothermal water, the condensed liquid is pumped back underground.

In these conventional Rankine cycle engines, the power of the pump to send the condensed working medium back to the evaporator, heater, or underground can have a significant impact on the overall efficiency of the engine, depending on the working medium, its temperature, and pressure. In extreme cases, 30% of the engine output
It may reach a certain extent.

This tendency is strong in steam turbines for low temperatures and organic medium turbines for low temperature differences.

The present invention uses solvent vapor evaporated from a heated solution as a working medium, drives an expander with this solvent vapor, cools and condenses the solvent vapor whose temperature has been lowered in the expander, and half the condensed solvent. This paper proposes a power generation method that utilizes the permeability of a permeable membrane to reduce the original solution and reflux it.

An embodiment of the present invention will be described below based on the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes an evaporator, which is composed of a steam drum la, a solution drum 1b, and an evaporator tube section 1c connecting these.

2 is a superheater that superheats the solvent vapor generated from the steam drum 1a; 3 is an expander starting valve connected to the superheater 2;
4 is an expander, for example a turbine type one, and 5 is, for example, a generator driven by the expander 4.

6 is a condenser that cools and condenses the solvent vapor expanded by the expander 4 and reduced in pressure and temperature.

7 is a semipermeable membrane chamber incorporating a semipermeable membrane 7a as a partition wall, and a lower chamber 7b partitioned by the semipermeable membrane 7a is connected to the condenser 6.
The upper chamber 7c is connected to the ascending pipe 8 and the descending pipe 9.
The solvent condensed in the condenser 6 is connected to the solution drum 1b of the evaporator 1 through the semipermeable membrane 7a of the semipermeable membrane chamber 7.
is used as a partition wall to face the solution in the solution drum 1b, and the solvent flows into the solution side due to the properties of the semipermeable membrane 7a, and the volume of the lower chamber 7b occupied by the condensed solvent is greater than the volume of the upper chamber 7c occupied by the solution. is also configured to be large.

The solution in the evaporator 1 fills the lower space of the steam drum 1a with which the evaporator tube 1c communicates, the solution drum 1b, and the upper chamber 7c of the semipermeable membrane chamber 7.

Further, the ascending pipe 8 and the descending pipe 9 are provided with valves 8a and 9a, respectively, which open when the expander 4 is activated.

Now, with valves 3.8a and 9a closed, heat the evaporator pipe section 1c and superheater 2 with combustion gas, exhaust gas, hot air, etc., and generate enough solvent vapor (solutes such as salts) to start the expander 4. Even if the electrolyte is sucrose,
It may be a non-electrolyte such as alcohol or other organic compound, but it must have a sufficiently high boiling point compared to the solvent so that the majority of the vapor generated is solvent vapor). When the valves 3.8a, 9a are opened at this point, the solvent vapor drives the expander 4 and the generator 5 is activated.

The solvent vapor that has been reduced in pressure and temperature in the expander 4 is condensed in the condenser 6 and falls by gravity into the lower chamber 7b of the semipermeable membrane chamber 7.

This condensed solvent contains little or no solute, and is therefore sufficiently diluted from the original solution.

Here, the osmotic pressure of the semipermeable membrane 7a is P.

, the pressure of the solution in the 1x3 chamber 7c in contact with the semipermeable membrane 7a is P
i, When the pressure of the condensed solvent in the lower chamber Ib is Pc, if values of Pi and Pc are selected such that the inequality Pi-PC<Po is established between them, the second As shown in the figure, the condensed solvent refluxes into the solution, forming a Rankine cycle.

Here, the semipermeable membrane chamber 7 is provided at a lower position than the solution drum 1b, and the solution whose specific weight has become smaller due to dilution due to the infiltration of the condensed solvent is partially removed from the upper part of the upper chamber 7c of the semipermeable membrane chamber 7. It enters the solution drum 1b through tube 8.

On the other hand, the solution in the lower part of the solution drum 1b, which has a large specific weight and a relatively low temperature and a high concentration, descends through the downcomer pipe 9 and flows into the semipermeable membrane chamber 7.
The solution flows into a relatively low part of the upper chamber 7c, is replaced with a dilute solution with a low specific gravity, and is cooled, and the solution near the semipermeable membrane 7a is always kept at the required concentration and temperature.
A predetermined osmotic pressure can be obtained.

Although the operating cost is higher than the above configuration, in order to obtain a predetermined osmotic pressure, a circulation pump may be provided to circulate the solution in the upper chamber 7c of the semipermeable membrane chamber 7 and the solution in the solution drum. A circulation pump may be provided between 1a and solution drum 1b, both within the scope of the present invention.

In addition to water, the solvent can be organic media such as fluorocarbon media, hydrocarbon media such as propane, butane, and pentane, alcohol media such as trifluoroethanol, fluorine carbide media, and inorganic media such as ammonia. Each can be used with appropriate solutes.

In short, a solution is created by dissolving a solute in a solvent, the amount of solvent vapor generated by heating this solution is greater than the solute vapor, the condensed vapor is sufficiently diluted than the original solution, and the semipermeable membrane 7a Any combination that generates an osmotic pressure that is reduced to the original solution through the solution may be used.

There are few semipermeable membranes currently on the market that are heat resistant, but in the configuration shown in Figure 1, when the expander is operating, the low temperature condensed solvent passes through the semipermeable membrane, so the semipermeable membrane is heat resistant. The membrane is kept at almost the same temperature as the condensing solvent.

Furthermore, if the volume occupied by the condensed solvent in the lower chamber 7b of the semipermeable membrane chamber 7 is made sufficiently smaller than the volume occupied by the solution in the 17-part chamber 7c, even when the expander is stopped, the valve 8a, If 9a is closed, there will be no solution moving between the upper chamber 7c of the semipermeable membrane chamber 7 and the solution drum 1b, and the temperature of the condensed solvent in the lower chamber 7b of the semipermeable membrane chamber 7 will be almost the same as when the expander is operating. Similarly, the temperature of the semipermeable membrane 7a is also kept low.

If there is no problem with the heat resistance of the semipermeable membrane, that is, if the semipermeable membrane has sufficient heat resistance or the solvent evaporation temperature is within the heat resistance temperature of the semipermeable membrane, the valve 8a in FIG. 9a becomes unnecessary, and furthermore, the upper chamber 70' of the semipermeable membrane chamber 7 may also serve as a solution drum as shown in FIG.

In this case as well, the solution near the semipermeable membrane 7a is always maintained at the required concentration and temperature through the evaporator tube portion 1c, and a predetermined osmotic pressure is obtained.

In FIG. 3, it is also possible to heat the upper chamber 7c' of the semipermeable membrane chamber 7, in which case 1c becomes a mere rising pipe for steam and a descending pipe for solution.

Furthermore, the upper chamber of the semipermeable membrane chamber may be the steam drum itself, and the semipermeable membrane chamber may be directly heated.

For example, as shown in Fig. 4, the semipermeable membrane chamber ``bottom chamber 7c'' is also used as a steam drum, and the heat exchange pipe 10 is inserted into the upper chamber 7c'', and the heat source is exhaust gas, hot air, or high-temperature liquid. flow.

Here, high temperature means higher temperature than the refrigerant (cooling water, etc.) in the condenser, and as in the case of ocean thermal power generation, the heat source is surface water and the cooling water in the condenser is deep water ( 7°
C), even if the surface water temperature is about 8°C, it can be used as a heat source because it is lower than the cooling water temperature.

The present invention can also be applied to a steam expander 4F cycle that is used in conjunction with a so-called hot water turbine or a gas-liquid mixing turbine called a total flow turbine.

As described above, according to the present invention, the working medium is refluxed into the solution using the osmotic pressure generated by the semipermeable membrane, so it can be carried out without the need for a conventional pump to convey the condensed working medium to the evaporator. In particular, it is possible to significantly improve the overall efficiency of Rankine cycle engines that operate at low temperature differences.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing one embodiment of the present invention, Figure 2 is a diagram explaining osmotic pressure due to the semipermeable membrane of the main part, and Figures 3 and 4 are configuration diagrams showing other embodiments. It is. 1... Evaporator, 1a... Steam drum,
1b...Solution drum, 3...Expander starting valve, 4...Expander, 5...
...Motor, 6...Condenser, 7...Semipermeable membrane chamber, 7a...Semipermeable membrane, 8...Rising pipe, 9.・・・・Down pipe.

Claims (1)

[Claims] 1 Heat the solution to evaporate the solvent in the solution, guide the solvent vapor to an expander to do expansion work, then cool and condense, and direct the condensed solvent to the solution using a semipermeable membrane as a partition wall. A power generation method characterized by refluxing this solvent into a solution.