JPH0411759B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a downhole pump for pumping underground hot water.

When installing a downhole pump to pump underground hot water, the well itself is normally sealed and kept as a sealed tank. However, because heat is dissipated into the atmosphere and bedrock, the temperature in the upper layer of the well, especially in the gas phase, decreases. Due to this temperature drop, the pressure in the gas phase kept at the saturated vapor pressure decreases. Therefore, sufficient pump suction pressure cannot be secured and operation becomes impossible.

The present invention solves the above-mentioned problems in equipment that pumps up hot water by equipping a hot water well with a downhole pump, and provides an operating method that can maintain the suction pressure of the downhole pump and stably continue the operation of ground facilities. The purpose is to

The present invention maintains the temperature inside the well uniformly and obtains stable pump operation by flowing a portion (very small amount) of the hot water discharged above the ground into the hot water extraction well through the warming pipe.

The present invention relates to the operation of a downhole pump for pumping up underground hot water, which is equipped with pressure holding means in the discharge piping, and in which the discharge of the downhole pump is applied to a well in which the downhole pump is installed. A system for pumping up underground hot water that supplies a much smaller amount of hot water from the hot water source to the well through piping to the well, uniformly raising the gas phase temperature in the well and maintaining the pump suction pressure. In the operating method of a hole pump, the hot water source is hot water pumped from a private well, and the piping from the hot water source to the well is connected at one end to a discharge pipe above ground. This is a method of operating a downhole pump for lifting.

Embodiments of the present invention will be described below with reference to the drawings. 1 is a production well, and 2 is a return well. In the production well 1, a pipe casing 4 is inserted through a low permeability stratum 5 so as to reach a porous stratum 3 from which hot water gushes out, and the area around the pipe casing 4 near the ground is hardened with, for example, concrete 6. . The production well 1 is sealed above ground with a lid 7 so as to withstand the high internal pressure.

The reinjection well 2 has a similar structure, with 8 being a pipe casing, 9 being concrete, and 11 being a lid. The reinjection well 2 is provided in a porous stratum 3 connected to the production well 1, and is placed in a position where it does not affect the amount of hot water springing from the production well 1 and the temperature of the hot water.

A hot water pump 12 is submerged in a liquid phase 11 of hot water gushing out at the location of the porous stratum 3 of the production well 1 . There are various types of hot water pumps 12, but they are based on deep well pumps that have a motor at the bottom and a pump at the top, and can be operated in high-temperature environments, and are generally considered to be downhole pumps. The hot water pump 12 passes through the lid 7 and is suspended and supported by a discharge pipe 15 fixed to the lid 7. A discharge pipe 15 extending to the ground via a check valve 14 is arranged from the hot water pump 12, and the discharge pipe 15 is connected to the gate valve 1.
6 to a primary pipe 18 on the heat transfer side of a heat exchanger 17 installed on the ground, and the pipe 18 passes through a lid 10 from the heat transfer side of the heat exchanger 17 to the pressure Reduction well 2 via holding means 19
Leads inside.

The heat receiving side of the heat exchanger 17 is connected to a pipe 23 from a heat medium pump 22 that sucks up liquid from the condenser 21 and sends it out.
The pipe 24 communicates with its inlet and exits from its outlet.
is in communication with the steam inlet of the steam turbine 25, and the steam outlet of the steam turbine 25 is in communication with the condenser 21 through a pipe 26.

The steam turbine 25 is connected to a generator 27 via a shaft coupling, and a cable 28 is incorporated into the hot water pump 12 so as to take out a part of the output of the generator 27.
It leads to 9.

A bypass pipe 33 is provided via a gate valve 31 and a flow rate regulating valve 32 so as to communicate between the discharge pipe 15 on the upstream side of the gate valve 16 and the gas phase 30 of the production well 1 .

Although not shown in the drawings, the power generation plant using underground energy as described above can be started by, for example, using electric power from another commercial power source to power the hot water pump 12 and the motor 29.
In a steady state, power is supplied from the generator 27 to the commercial power source side, and power is also supplied from the generator 27 to the hot water pump 12 and the motor 29.

The hot water pumped up by the hot water pump 12 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 15, the gate valve 16 used, and the piping 18, and reaches the heat exchanger 17. The heat receiving side of the heat exchanger 17 sends the heat medium sucked from the condenser 21 into the secondary side of the heat exchanger 17 by the heat medium pump 22, and is heated by hot water passing through the primary side. The hot water whose temperature has decreased is transferred to the pressure holding means 19
The pressure decreases to match the internal pressure of the reinjection well 2 and enters the reinjection well 2. With such pressure holding means 19, the pressure holding means 1 is maintained from the discharge side of the hot water pump 12.
The hot water up to No. 9 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. Note that the temperature from the pressure holding means 19 to the reinjection well 2 has decreased and the hot water has become a liquid phase.
Moreover, the critical pressure is maintained by the pressure inside the reinjection well 2. It is desirable that the reduction well 2 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 hot water whose temperature has been reduced and is returned to the reinjection well 2 is returned to the porous stratum 3 against the injection pressure of the reinjection well 2 .

The heat medium sent out by the heat medium pump 22 and turned into superheated steam in the heat exchanger 17 is supplied to the steam turbine 25 through the pipe 24, and the heat and pressure energy held in the steam turbine 25 are converted into power and the steam turbine is powered. 25, the steam turbine 25 rotates the generator 27 and generates electricity. The heat medium leaving the steam turbine 25 passes through a pipe 26, is liquefied in a condenser 21 equipped with a heat medium cooling means (not shown), and is sucked into a heat medium pump 22 and circulated.

As described above, in geothermal power generation, in a closed Rankine heat engine cycle in which hot water is guided from the production well 1 to the return well 2 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.

During operation, the gas phase 30 of the well is heated by the hot water pump 1.
2, it is necessary to maintain stable pressure in order to generate suction pressure. Then, the gate valve 31 is opened, the flow rate is adjusted by the flow rate regulating valve 32, and a portion of the hot water is returned to the gas phase 30 of the well from the above ground portion of the discharge pipe 15 through the bypass pipe 33. In the gas phase 30 of the well, heat is taken away by the surrounding soil, bedrock, etc., so the temperature tends to decrease and the saturated steam pressure at that time is exhibited, so if the temperature decreases significantly, the pressure decreases and the hot water pump 12 can't be inhaled. Bypass piping 33
Since a very small portion of high-temperature hot water is constantly supplied to the gas phase 30, the gas phase 30 rises in temperature and exhibits a corresponding pressure, allowing the hot water pump 12 to operate stably.

Although the bypass piping 33 in the embodiment returns the gas to the gas phase 30 of the well, it is also effective to return the gas to a relatively upper part of the liquid phase 11 of the well. It has the effect of raising the temperature of 30.

As described above, the present invention allows a very small amount of hot water to enter the production well compared to the amount of hot water discharged from the discharge pipe, so the temperature inside the well is kept uniform, ensuring stable pump suction pressure, and the pump is safe. made it possible to drive. In addition, since piping is generally simple and small in diameter, equipment costs are low.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of an embodiment of the present invention. 1... Production well, 2... Reduction well, 3... Porous stratum, 4
...Pipe casing, 5...Low permeability stratum, 6...Concrete, 7...Lid, 8...Pipe casing, 9
...Concrete, 10...Lid, 11...Liquid phase, 12...
Hot water pump, 14... Check valve, 15... Discharge pipe, 16
...gate valve, 17...heat exchanger, 18...(primary) piping, 19...pressure holding means, 21...condenser, 22...
Heat medium pump, 23, 24... Piping, 25... Steam turbine, 26... Piping, 27... Generator, 28... Cable, 29... Motor, 30... Gas phase, 31... Gate valve, 32... Flow rate adjustment valve, 33 …Piping.

Claims (1)

[Claims] 1. Operation of a downhole pump for pumping up underground hot water, which is equipped with a pressure holding means in the discharge piping,
During the operation of the downhole pump in the well where the downhole pump is installed, an amount of hot water that is extremely smaller than the discharge amount of the downhole pump is supplied from the hot water source to the well through the piping to the well, and the gas phase temperature in the well is maintained. In the operating method of a downhole pump for pumping up underground hot water, which uniformly raises the water pressure and maintains the pump suction pressure, the hot water source is hot water pumped from a private well, and the flow from the hot water source to the well is A method of operating a downhole pump for pumping up underground hot water, characterized in that one side of the piping is connected to a discharge pipe above ground. 2. The method of operating a downhole pump for pumping up underground hot water according to claim 1, wherein the opening position in the well of the piping from the hot water source to the well is a space in the well with a gas phase. 3. The method of operating a downhole pump for pumping up underground hot water according to claim 1, wherein the opening position in the well of the piping from the hot water source to the well is a space in the well where the liquid phase exists.