JPS6030497A - Method and device for initial operation of downhole pump for pumping up underground hot water - Google Patents

Abstract

PURPOSE:To provide safety operation through securement of the suction pressure of a pump by throttling the amount of discharged water onto the ground facility side, retarding the rising speed of the underground hot water, and at the same time returning part of the discharged hot water from a piping for initial operation back to the well, and thereby lessening the temp. change of the hot water sucked in the pump. CONSTITUTION:In the initial period of pumping operation, a gate valve 9 throttles the amount of hot water Q discharged onto the ground facility side and lessens the amount of hot water Q' raised from the shaft bottom 7, so as to make mild the rise of the hot water from shaft bottom 7. Here, part (q) of the hot water discharged from a by-pass piping 11 for initial operation is returned to the well 2. At this time the intra-well temp. above pump 4 can be made even by enlarging the (q) as much as possible. Accordingly the temp. change caused by the hot water rising from the shaft bottom 7 can be made mild by making Q' smaller and (q) larger to provide an even temp. around the pump 4 and thereabove, and thereby the pump 4 is secured with sufficient suction pressure to enable safety operation.

Description

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

In hot water wells that have been shut down for long periods of time, the temperature at the top becomes lower than the bottom temperature due to heat dissipation into the atmosphere and bedrock. Figure 81 is a diagram showing the temperature distribution in a sealed hot water well when the pump is stopped.The temperature at that position is taken in the horizontal direction from the vertical coordinate Y-Y, and the temperature distribution line / is shown in the diagram. O is on the ground. A downhole pump (hereinafter simply referred to as pump) 4L is installed in the liquid phase part 3 of the hot water well, and a discharge pipe connected to the pump! The liquid is sent to the ground.

For example, as shown in the figure, the temperature of the hot water is 200°C at the bottom 7 of the mine, but the temperature decreases as it goes to the upper layer, and in the gas phase, the temperature is constant everywhere at 100°C because it is in a saturated steam state. In some cases.

In such a case, if the pumper is operated without considering the above-mentioned temperature difference, the 200° C. hot water at the bottom of the mine 7 will rise rapidly, resulting in a very large temperature change in the hot water sucked into the pump bower. In addition, the gas phase section 6 and the main parts above the liquid remain at 'low' temperatures, making it impossible to ensure sufficient pump suction pressure. This makes the pump inoperable.

SUMMARY OF THE INVENTION An object of the present invention is to provide an operating means that ensures pump suction pressure at the time of starting a downhole pump installed in a hot water well to ensure smooth startup of the pump.

The present invention is a device provided with an initial operation bypass piping that communicates the discharge pipe of a downhole pump installed in a hot water well or other hot water source with the gas phase of the well via a flow rate adjustment means, By reducing the amount of hot water discharged to the above-ground equipment and slowing down the speed at which underground hot water rises, some of the hot water discharged from the bypass piping for initial operation can be returned to the well, or heat can be extracted from other hot water sources. By introducing water, the temperature change of the hot water sucked into the pump is reduced, ensuring sufficient pump suction pressure, and the pump can be operated safely.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 2 shows a longitudinal section of a hot water well and also shows a diagram showing the temperature distribution of the hot water well, and the diagram showing the temperature distribution is shown in the same manner as in Figure 1. Y-, Y are vertical coordinates, and the origin O indicates the ground.

The discharge pipe 3 of the pump pavilion is hermetically inserted through the lid of the well above ground. And flow to the ground facility side! They are connected via a gate valve 9 which can also be adjusted.

On the ground facility side, hot water supplied from a hot water well (hereinafter referred to as a well) is guided to a heat exchanger, the heat medium is used as superheated steam, the superheated steam drives a steam turbine, and the steam turbine drives a generator. The primary hot water that exits the heat exchanger is sent to the reinjection well.

An initial operation bypass pipe /l is provided that communicates between the upstream side of the gate valve 9 of the discharge pipe S and the gas phase part 6 of the well λ,
The bypass pipe // has a thermometer 7.2 that measures the temperature of the liquid in the bypass pipe //, and a gate valve that opens at the beginning of operation after startup.
41, a flow rate adjustment valve /3 is interposed to adjust the flow rate of the liquid flowing through the bypass pipe /l. In addition, bypass piping //
may be communicated into the well a from another hot water source, for example from another hot water well.

At startup, the gate valve /l is opened and the gate valve is throttled. When the pump is energized, the hot water is sent to the above-ground facility through the discharge pipe 3, but a portion of the hot water is returned to the gas phase section 6 of the well through the bypass pipe /1.

Let Q be the amount of hot water discharged from the pump bower to the inland equipment side, and let q be the amount of hot water returned from the initial operation bypass piping/l into the well. In this case, the flow rate discharged from the pump pavilion is Q+q, and the amount Q' of hot water rising from the bottom of the mine is equal to the amount Q discharged to the ground equipment side.

At the beginning of operation of the pump station, the amount of hot water Q discharged to the ground equipment side is throttled by the gate valve D, and by reducing Ql, the rise of the hot water from the bottom 7 is made gradual.

At this time, two parts q of the hot water discharged from the initial operation bypass pipe are returned to the well. At this time, by making q as large as possible, the temperature in the well above the pump bow can be made nearly uniform.

Therefore, by reducing Q' (=Q) and increasing t and q, the temperature change caused by the hot water rising from the bottom of the mine can be moderated, and the temperature near the pump II and above it can be made nearly uniform. In this condition, sufficient suction pressure of the pump can be ensured and the pump can be operated safely.

Now, let's take a look at the temperature 1p at the inlet of the pump's suction port during its initial operation. When the pump trough is started and operated for a certain period of time, the hot water in well a from underground 7 to the pump trough rises, and the hot water at the bottom of the well rises to position 15, and from bottom 7 to position 15. Constant temperature T. So, as if the temperature distribution line / in Figure 1 was superimposed with position 15 as the reference [・
Therefore, the temperature of the increased hot water [at the location of the pump pavilion] becomes T. On the other hand, the flow rate of a part of the hot water returned from the bypass pipe // to the gas phase part B is q, and as shown by the line with code /7, the flow rate of the hot water drops to the saturation temperature t1 of the gas phase part B in the gas phase part B. The liquid reaches the liquid level in the liquid phase section 3. The liquid then liquefies at the liquid level 16 and gradually decreases in temperature from t1 to t and is sucked into the pump chamber. Since the suction liquid is a mixture of hot water rising from the bottom 7 side and hot water returning through the gas phase section 6, the temperature t at the inlet of the suction port of the pump pavilion is . T, t, and tp will increase with time, but when starting the pump bow, tighten the gate valve or, if the pump bow is a variable discharge type pump, reduce the discharge volume of the pump bow to send it to the ground facility. By decreasing the liquid amount Q and increasing the return amount q, the change in T is decreased and the temperature difference between T, t, and tp is decreased. In this way, the pressure in the gas phase part B is increased and the suction pressure of the pump can be secured. As shown by the dotted line with the symbol "it", the hot water sucked in by the pump stall gradually loses its heat in the discharge pipe S by the gas in the gas phase B, and reaches a temperature t' on the ground.

The present invention is designed to adjust the flow rate and return a portion of the hot water discharged from the discharge pipe into the well from the bypass pipe or other hot water source when the downhole pump gets stuck in the initial operation state where the temperature inside the well is uneven. Equipped with piping that guides hot water into the well, during the early stages of operation, the amount of hot water sent to the above-ground equipment is throttled, and temperature changes due to hot water rising from the bottom of the well are moderated.
In addition, since the hot water discharged into the well is returned from the bypass piping for initial operation installed at the above-ground discharge part, or the hot water is sent into the well from another hot water source, the hot water sucked into the pump is reduced. This reduces temperature changes in the pump and at the same time ensures sufficient pump suction pressure, making it possible to safely initialize the pump.

Therefore, according to the present invention, the pump can be safely operated from a stopped state where there is a large difference in temperature within the well to a steady state (where the temperature within the well is only partial).

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the temperature distribution when the well pump is stopped, and FIG. 2 is a longitudinal sectional view of an embodiment of the present invention. l...Temperature distribution line Co...Hot water well 3...Liquid phase part Da...Pump S...Discharge pipe 6...Gas phase part Ri...Bottom of the well Z...Lid 9...Gate valve/l...・Bypass piping for initial operation /, 2.. Thermometer /3.. Flow rate adjustment valve l da.
・Gate valve! ! ··position. Patent applicant Ebara Corporation Agent Arai -be

Claims (1)

[Claims] l In the initial operation of a downhole pump that pumps up underground hot water, the amount of hot water discharged to above-ground equipment is reduced to slow down the speed at which underground hot water rises, and at the same time the downhole pump is discharged. By extracting some of the hot water on or near the ground or leading it from another hot water source and introducing it into the well, the temperature change of the hot water sucked into the downhole pump is reduced and sufficient pump suction pressure is ensured. Initial operation method for downhole pumps for pumping underground hot water to safely operate downhole pumps. (Y) Provide bypass piping for initial operation that communicates from the discharge pipe of a downhole pump that pumps underground hot water from a well to the gas phase part of the well via a flow rate adjustment means, and also includes means for making the pump discharge rate variable. Initial operation equipment for a downhole pump for pumping up underground hot water.