JPS6030794A - Stand-by method of well for pumping up underground hot water - 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 device that uses geothermal energy to convert it into power, for example, to generate electricity.

The development of geothermal power generation is at the stage of transitioning from experimental plants to commercial plants. In geothermal power generation, when a production well from which hot water gushes is sealed, a gas phase exists at the top and a liquid phase exists at the bottom in equilibrium at critical pressure. In this liquid phase, it can withstand high pressure and high temperature hot water,
In addition, a high-head pump (hereinafter simply referred to as a hot water pump) is submerged, and the hot water gushing out from the pump is guided to the ground through a heat exchanger and returned to the reinjection well, and the heat medium exchanged with the heat exchanger is The superheated steam is led to a steam turbine, and the steam/steam turbine energizes a generator to generate electricity. Such a method is typical in geothermal power generation.

When restarting a hot water pump installed in a well that pumps underground hot water after stopping it for a short period of time, it is necessary to perform steady operation in the shortest possible time. .

There are two problems with this cleaning process.

(1) When the hot water pump is stopped, the hot water in the discharge pipe escapes from the discharge pipe because there is a leak in the check valve installed in the discharge pipe near the pump outlet, and when the pump is restarted, the hot water escapes from the discharge pipe. In this case, the operation must be started to fill the inside of the discharge pipe, which delays the time required to reach a steady state. Some of the wells that gush out hot water are hundreds of meters deep, and it takes a long time just to fill the discharge pipes.

(2) If the well is left with the hot water pump stopped, the temperature at the top of the well will drop, so operations must be performed to stabilize the temperature inside the well when restarting.

As a result, it takes a long time for ground facilities to reach a steady state.

An object of the present invention is to provide a method for shortening the time from the start of a hot water pump to reaching a steady state, the so-called rise time, by retaining hot water in the discharge pipe and reducing the temperature inside the well. shall be.

The present invention relates to a closed well that gushes out hot water, which houses a pump for pumping up hot water, and is equipped with a discharge pipe that leads the pump to a heat exchanger on the ground via a check valve, in which the above ground portion of the discharge pipe is provided. Hot water from another hot water source is drawn into the discharge pipe to pressurize the inside of the discharge pipe, and one end communicates with a sealed well from which the hot water gushes out, and the other end communicates with another hot water source. Warming piping is installed to draw hot water from an external heat source into the discharge pipe, and other hot water is drawn into the well through the warming piping to raise the temperature of the well and stand by so that it can be started quickly. be.

Embodiments of the present invention will be described below with reference to the drawings. / is a production well, and ko is a reduction well. The production well l has a low permeability stratum with pipe casing t so as to reach the porous stratum 3 where hot water gushes out! It is inserted through the pipe casing 1, and the area near the ground is hardened with concrete 6, for example. The production well 1 is sealed above ground with a lid to withstand high internal pressure.

The reinjection well has a similar structure, with S being a pipe casing, Ri being concrete, and 10 being a lid. The reinjection well is installed in the porous stratum 3 that is connected to the production well 1, but it is placed in a position that will not affect the hot water spring cover and the temperature of the hot water in the production well 1.

A hot water pump /, 2 is submerged in the liquid phase of hot water gushing out at the position of the porous stratum 3 of the production well l. There are various types of hot water pumps, but they are based on deep well pumps with a motor at the bottom and a pump at the top, and are capable of operating in high-temperature environments, and are generally considered to be downhole pumps. The hot water pump is suspended and supported by a discharge pipe /j connected to its discharge port fixed to the lid 7. A discharge pipe is extending from the hot water pump /2 to the ground via a check valve /'l, and a discharge pipe /j is connected to the heat transfer side of the heat exchanger /2 installed on the ground via a gate valve 16. The lid IO is connected to the primary pipe /r from the heat transfer side of the heat exchanger 17.
Is there a pressure holding means such as a throttle valve? It leads into the reinjection well λ via.

On the heat receiving side of the heat exchanger/li, a piping 3 is connected to the inlet from a heat medium pump 2-2 that sucks up and sends out the liquid from the condenser 21, and a piping 21I coming out from the outlet is connected to the steam turbine λ.
The steam outlet of the steam turbine 2j is communicated with the condenser J/ through a pipe 2B.

The steam turbine 2j is connected to a generator 27 via a shaft coupling, and a cable 2 is connected to the generator 27 so as to take out a part of the output of the generator
g is connected to a motor built into the hot water pump/co for driving a heat medium pump.

The gas phase 3θ between the discharge pipe IS and the production well on the downstream side of the check valve l
A warming bypass piping is connected via a gate valve 31 and three flow rate adjustment valves so as to communicate between the ? 3 is a provision. The three flow rate adjustment valves are provided when flow rate adjustment is required, and are not provided here if they are installed in the intake piping, which will be described later.

Is there hot water discharged from another well or other hot water source in the discharge pipe/j? A hot water inlet pipe J'7 is provided to introduce hot water from 4I through the pressure regulating valve 3j.

Although not shown in the figure, to start a power generation plant using underground energy as described above, for example, the hot water pump/:11 motor 2q is started using electric power from another commercial power source, and in a steady state, the electricity is transferred from the generator core to the commercial power source side. In addition to supplying electric power, the generator 27 also supplies electric power to the hot water pump 12, motor, and 29.

The hot water pumped up by the hot water pump/:l is discharged at a pressure equal to or higher than the critical pressure corresponding to the temperature of the hot water.

Then, it passes through the discharge pipe /k, the gate valve /6 used, and the pipe lza, and reaches the heat exchanger 17.

Heat exchanger/? The heat receiving side of is sending the heat medium sucked from the condenser 21 into the secondary side of the heat exchanger/7 by the heat medium pump here, and is heated by the hot water passing through the negative side. The hot water whose temperature has been lowered passes through the pressure holding means /9 to a pressure corresponding to the pressure inside the reinjection well, and enters the reinjection well. By means of the pressure holding means /9, the pressure holding means l? The hot water is kept above the critical pressure and does not vaporize, so minerals such as calcium carbonate contained in the hot water do not precipitate, thereby preventing clogging of piping.

The temperature in the reinjection well 2 years old from the pressure holding means 19 has decreased and the hot water has become liquid, and the critical pressure is maintained by the pressure inside the reinjection well. It is desirable that the reduction well does not exhibit a gas phase, and it is desirable that the injection pressure is such that the hot water to be reduced is maintained at a critical pressure or higher. The reduced temperature hot water that is returned into the reinjection well returns to the porous stratum against the injection pressure of the reinjection well.

The heat medium sent out by the heat medium pump and turned into superheated steam at the heat exchanger is supplied to the steam turbine Jj through the piping. The heat held in
The pressure energy is converted into power and rotates the steam turbine 2s, and the steam turbine 2t rotates the generator core to generate electricity.

The heat medium exiting the steam turbine 3 passes through a pipe t, is liquefied in a condenser 2/ equipped with a heat medium cooling means (not shown), and is sucked into a heat medium pump 221 and circulated.

As mentioned above, in geothermal power generation, in the closed Rankine heat engine cycle in which hot water is guided from the production well to the return well through a heat exchange relationship, the primary side equipment through which the hot water passes maintains the hot water in a liquid phase by the pressure holding means 19. This is how the pressure is maintained.

Now, warming bypass piping 33, hot water extraction piping 37
If the hot water pump 12 is stopped and there is a leak in the check valve/1I, the hot water in the discharge pipe ls will leak from the check valve/2 and flow back through the hot water pump/2 and become liquid. phase//
Return to Due to the backflow of hot water from the discharge pipe/j, the discharge pipe/!
The water level in r will fall. Then, the inside of the discharge pipe lj becomes a gas phase in which the hot water inside the discharge pipe /j is vaporized. According to the stop time of the hot water pump 12, the production well l is cooled by removing heat from the surrounding soil and bedrock. Therefore, when the hot water pump 12 is restarted, it will take some time for the hot water to reach the ground facility until the discharge pipe/lt is filled.The hot water will be cooled midway for a considerable period of time after the pump is started. It takes a long time to reach a steady state and to be able to start operating the turbine 2g.

Therefore, in the present invention, when the hot water pump 2 is stopped, the gate valve 36 is opened, and hot water is introduced from the hot water source 31 into the discharge pipe 13 from the hot water inlet pipe 3 via the pressure regulating valve J. The introduced hot water has a high temperature liquid phase, and the inside of the discharge pipe 15 is filled with hot water. Open the gate valve 31 here and open the flow rate adjustment valve 3.
Warming bypass piping, through 2? 3 into the production well 7. This overcomes the heat radiation from the production well to the surrounding soil and bedrock and keeps the inside of the production well warm.

Is there a hot water source for scrubbing such a hot water pump so that it can operate even when the hot water pump/2 is stopped? For example, hot water from another production well is introduced, gate valve J is opened, heat exchanger I is operated, and turbine generator S is operated. When the hot water pumps / and 2 are stopped, the gate valve /6 is closed, and when the operation of the above-ground facilities is stopped, the amount of hot water extracted into the production well 1 is as small as necessary for heat retention.

To start the hot water pump/co, close the gate valves 31 and 31 and open the gate valve 16.

In the embodiment, one end of the warming piping is connected to the discharge pipe to take in hot water from another hot water source that once entered the discharge pipe, but the example is not limited to this, and the hot water source is directly connected to the production well and the discharge pipe. Hot water may be supplied in parallel.

Furthermore, in order to keep the heat exchanger warm, a gate valve is provided on the outlet side of the heat exchanger in the primary piping of the heat exchanger, and hot water from another hot water source is introduced from the upstream side of this gate valve. Alternatively, the hot water may flow backward from the primary side piping of the heat exchanger, and the gate valve 16 between the discharge pipe and the ground facility may be opened to supply another heat source to the discharge pipe when the hot water pump is stopped.

As described above, the present invention includes an inlet pipe that injects hot water from a hot water source such as a well where other hot water gushes out into the above-ground discharge part of a hot water pump that is stopped, and an inlet pipe that injects the hot water from a hot water source such as a well into a production well. By installing warming piping that leads to the While the hot water pump is stopped, the inside of the well is kept at a constant temperature because it is being extracted into the production well, and the gas phase of the well is kept at a high critical pressure to ensure the suction pressure of the hot water pump.

From the above, hot water is discharged at a constant flow rate immediately after restarting, and steady operation is possible.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of an embodiment of the present invention. /... Production well Co... Reduction well 3... Porous stratum l...
・Pipe casing!・・Low permeability stratum 6・・Concrete 7・・Lid・・Pipe casing・・
Concrete /θ・・Lid /l・・Liquid phase 12・・Hot water pump /F・・Check valve /, 1・・Discharge pipe /6・・
Gate valve /7...Heat exchanger 7g...Piping/9...Pressure holding means Co/...Condenser, 22...Heat medium pump, 23. Cog...Plumbing, 2! r...Steam turbine 2
6... Piping, 27... Generator 2g... Cable,
2q...Motor 30...Gas phase 31...Gate valve 32...
・Flow rate adjustment valve 33...Piping 3'l...Hot water source 3s
・・Pressure adjustment valve 36・・Gate valve 37・・Hot water extraction piping. Patent applicant Ebara Corporation Agent Arai − Department

Claims (1)

[Scope of Claims] l A pump for pumping up hot water is housed in a closed well that gushes out hot water, and is equipped with a discharge pipe leading from the pump to a heat exchanger on the ground via a check valve. Hot water supply piping is used to constantly pressurize the inside of the discharge pipe by extracting hot water from another hot water source into the discharge pipe, with one end leading to another hot water source and the other end leading to the discharge pipe. A standby device for a well for pumping up underground hot water, characterized in that it is equipped with a warming pipe that connects one end to another hot water source and the other end to a closed well from which hot water gushes out. The standby device for a well for pumping up underground hot water according to claim 1, wherein the other hot water source is a hot water valve that gushes out another hot water. 3. The standby device for an underground hot water/pumping well according to claim 1, wherein the T end of the warming pipe is in communication with the discharge pipe.