JPS5925852B2 - Gas turbine geothermal turbine combination power generation plant equipment - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a power generation plant device that combines a gas turbine and a geothermal turbine, and particularly to a device that heats geothermal steam by utilizing waste heat of exhaust gas of a gas turbine. This relates to a power generation plant system that combines a gas turbine and a geothermal turbine.

[Background of the invention]

FIG. 1 shows an example of a known geothermal power plant system.

This will give an overview of the prior art.

There are regional differences in the steam or hot water obtained from underground, and the mixing ratio and composition of steam and water vary depending on the location, so the configuration of the power generation plant system also differs, but the mortar type example is the first. Figure 1.

Geothermal steam is extracted from a steam well 1.

The steam obtained from such a steam well 1 is collected by piping into a header 2, guided to a separator 3, and separated into moisture and steam.The steam then enters a geothermal turbine 4, which rotates the turbine, and is generated by a geothermal turbine generator 5. Generate electricity by

The steam that has finished generating electricity is condensed in a condenser 7 and guided to a hot water tank 8.

Further, the water separated by the separator 3 is directly led to the hot water tank 8.

The separator drain valve 6 is a pressure regulating valve provided to keep the water level within the separator 3 constant.

A portion of the hot water in the hot water tank 8 is pumped to the cooling tower 9 by the cooling tower feed water pump 10 and cooled, and the cold water is sent to the condenser 7 by the condenser cooling water pump 10 and used to condense steam. It will be done.

The condensed hot water in the hot water tank 8 is finally led to the return well 12 and returned underground.

The above is a geothermal power generation plant system that has been commonly used in the past, but the steam extracted from the steam well 1 is
Since it is usually saturated steam containing hot water, there are problems that need to be improved, such as scale adhesion, erosion within the turbine, and a decrease in internal efficiency.

In order to increase the internal efficiency of the geothermal turbine 4, it has been proposed to heat saturated steam with a heater and supply it to the turbine as superheated steam, as seen in Japanese Patent Publication No. 47-5022, for example.

However, the energy of the hot water pumped up from the steam well is simply thrown away, and it cannot be said that the thermal energy of the pumped steam and hot water is effectively utilized.

[Purpose of the invention]

The purpose of the present invention is to increase the output of geothermal turbines, improve efficiency, and prevent erosion by utilizing as much as possible the thermal energy possessed by the fluid pumped up from geothermal wells. An object of the present invention is to provide a gas turbine geothermal turbine combination power generation plant that improves the energy utilization rate of turbine fuel.

[Summary of the invention]

The present invention provides an exhaust heat recovery boiler that uses gas turbine exhaust heat as a heat source, and includes a first drum filled with water, a second drum filled with hot water and saturated steam, and a superheater that heats the saturated steam. The hot water and steam pumped up from the steam well are separated by a separator, and the separated steam is supplied to the second drum, and the hot water is supplied to the first drum. .

According to the configuration of the present invention, most of the fluid pumped up from the steam well is given to the waste heat recovery boiler, so the thermal energy held by the fluid is effectively utilized.

[Embodiments of the invention]

A gas turbine and geothermal turbine combination power generation plant to which the present invention is applied will be explained using an embodiment shown in FIG.

FIG. 2 shows in detail the range of A related to the present invention in FIG.
It is the same as the one shown in the figure.

Steam and hot water led from header 2 are passed through separator 3
The steam enters and is separated into steam and hot water, where the steam is led to the upper drum 17 of the heat recovery boiler 15 through a pipe 27 equipped with a steam inlet valve 13.

On the other hand, as shown in FIG. 1, the hot water passes through the separator drain valve 6 to enter the wet water tank through the piping line 29 and the drain flow valve 14 to the lower drum 16 of the exhaust heat recovery boiler 15.
It is divided into two piping lines 28 that lead to the exhaust heat recovery boiler 15, and the amount of drain flowing into the exhaust heat recovery boiler 15 is controlled as necessary.

The exhaust heat recovery boiler 15 is a drum type boiler, and includes a lower drum 16 filled with water and an upper drum 17 filled with almost saturated steam.
and an evaporation pipe 18 connecting these two drums,
Furthermore, it has a superheater 19 that heats the saturated steam from the upper drum 17 and converts it into superheated steam.

The exhaust heat recovery boiler 15 is configured to be heated by the heat of exhaust gas from a gas turbine, which will be described later, and the saturated steam from the separator 3 is guided to the upper drum 17 by a pipe 27 and enters the superheater 19. The hot water enters the lower drum 16 through the pipe 28, is heated in the evaporator tube 18, and then is led to the upper drum 17 and the superheater 19.

The superheated steam leaving the superheater 19 is guided to the geothermal turbine 4 through the high-pressure pipe 31, where the turbine 4 is driven to generate electricity in a geothermal turbine generator, and then guided to the condenser.

Heat input to the exhaust heat recovery boiler 15 is performed by exhaust gas from a gas turbine.

The air compressed by the gas turbine compressor 20 is guided to the combustor 21, mixed with fuel from the fuel tank 22, combusted, and guided to the gas turbine 23, which rotates the gas turbine 23 and generates a gas turbine generator. 24 to generate electricity.

Exhaust gas from the gas turbine 23 is led to the exhaust heat recovery boiler 15 through the exhaust gas pipe 32, and heats the above-mentioned geothermal steam and hot water.

The heat auxiliary device 25 is used as an auxiliary device during regular inspections of the gas turbine.

The operating situation of the embodiment of the present invention has been described above, and the enthalpy entropy diagram in FIG. 3 is a diagram that explains the effect in more detail.

In FIG. 3, Pi indicates the steam pressure at the inlet of the geothermal turbine, and Pc indicates the steam pressure at the outlet of the geothermal turbine.

According to the present invention, the steam conditions at the inlet and outlet of the geothermal turbine change on the pressure line of Pi and Pc depending on how the geothermal steam is heated.

First, in conventional geothermal turbines like the one shown in Figure 1, the turbine inlet steam is usually saturated steam.
Looking at the diagram, the change inside the turbine is from A1 to B1, and the turbine output becomes Δio.

The line with constant entropy S extending downward from A1 is the expansion line in the case of no loss; B1 becomes the actual expansion line.

In this case, all state changes within the geothermal turbine occur in the wet steam region, with moisture losses and poor internal efficiency.

In addition, the moisture level at point B1 is high and causes the problem of erosion.

On the other hand, if the steam is converted into superheated steam by an exhaust heat recovery boiler using the exhaust gas of the gas turbine as a heat source and introduced into the geothermal turbine, the point A will move upward on the Pi line.

Gas turbine exhaust gas has a temperature of approximately 500°C, so it is natural for the temperature to be lower than this, but if the temperature is raised to point A3, for example, point B3 at the turbine outlet will become completely superheated steam, and the Pi and Pc lines will change to entropy. Since it tends to open as S increases, the power generation amount Δl' will be significantly larger than Δl, but this may cause the condenser to become larger, and normally A2. It is desirable to operate the geothermal turbine at a location where B2 is close to the saturated steam line, such as the B2 line.

If such an expansion line is used, the change in steam within the geothermal turbine occurs in the superheated steam region, eliminating losses due to moisture and improving the efficiency of the geothermal turbine.

In addition, there are no water droplets inside the geothermal turbine, damage to the rotor blades due to erosion does not occur, and output increases by the amount of waste heat recovered.

According to estimates, by using such a combined plant system, the efficiency of geothermal turbines can be improved from about 15% to about 25%, and about 45% of the exhaust heat of gas turbines can be recovered, The energy utilization rate of fuel can be increased to approximately 60%.

The above explanation is the effect of converting geothermal steam into superheated steam using an exhaust heat recovery boiler. Water is supplied, and since this hot water has reached nearly the saturation temperature, the boiler 15 is supplied with boiler feed water from a high area, and a large amount of steam can be generated.

That is, the amount of heat held by the hot water is effectively utilized by the geothermal turbine 4.

〔Effect of the invention〕

According to the present invention, the steam conditions of a geothermal turbine are improved;
Since the turbine can be made into a superheated steam region, it is possible to improve the internal efficiency of the geothermal turbine, prevent erosion, and increase the output.In addition, hot water pumped from the geothermal well can be used as water supply for the waste heat recovery boiler. Therefore, the amount of heat held in the hot water can also be recovered, making it possible to significantly improve the energy utilization rate of the fuel in the gas turbine.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a conventional geothermal power generation plant, Fig. 2 is a partial system diagram of a gas turbine and geothermal turbine combined power plant that is an embodiment of the present invention, and Fig. 3 is an enthalpy diagram showing the principle of the present invention. It is an entropy relationship explanatory diagram. 1...Steam well, 2...Header, 3
... Separator, 4 ... Geothermal turbine, 5 ... Geothermal turbine generator, 6 ...
Separator drain valve, 7... Condenser, 8...
...Hot water tank, 9...Cooler, 10...
・Water supply pump for cooling tower, 11... Condenser cooling pump, 12... Reduction well, 13... Steam inflow valve, 14... Drain flow Jinben, 15...
...Exhaust heat recovery boiler, 16...Lower drum, 1
7...Upper drum, 18...Water pipe, 19
...superheater, 20 ... gas turbine compressor, 21 ... combustor, 22 ... fuel tank, 23 ... gas Turbine, 24...
...Gas turbine generator, 25...Auxiliary combustion device, 27...Piping-28...Piping, 31
...High pressure piping, -32...Exhaust gas piping.

Claims (1)

[Claims] 1. An exhaust heat recovery boiler that heats steam and hot water led from a steam well to generate superheated steam, and a gas turbine that supplies burnt gas as a heat source for the exhaust heat recovery boiler. , a power generation plant comprising a geothermal turbine driven by superheated steam generated in the waste heat recovery boiler, the waste heat recovery boiler having a first drum filled with water and a first drum filled with hot water and saturated steam. It has a second drum and a superheater that uses saturated steam as heating steam, and further includes a separator that separates steam containing hot water supplied from the steam well into steam and hot water. A gas turbine geothermal turbine combination power generation plant device, characterized in that piping is provided for feeding separated steam and hot water to the second drum and the first drum of the exhaust heat recovery boiler, respectively. 2. The gas turbine geothermal turbine combination power generation plant device according to claim 1, characterized in that a heat auxiliary device is installed in the exhaust heat recovery boiler.