Company pearl secondary hydropower stations in the jiangxi province can is a private/suichuan jinggangshan region power station. High water head of 216 meters, is equipped with two horizontal type turbine, the total installed capacity of 8000 kw. Because there is no reservoir, only sand basin, so the water quality is poorer.

1, the introduction of technical water supply system:

due to belong to the high water head hydropower station, technology used in the pump of water supply water supply unit. After downtime due to water quality problems often result in pump damage to their reduced pressure water supply. As shown in figure 1, figure of Fx for globe valve ( F7 for electric hydraulic control Industrial Valves) ; Y ZJY46H - 25 c DN100 pressure reducing valve; H is dead slow close check valve; L for automatic water filter; Flow for the F1 - Y - F2 - H - L - F3 - to 1 # and 2 # unit respectively.

the original design for decompression after F6, F7, F8 to water filter to units. By the F7 and realize the remote control ( F2 closed) 。 Because of F7 often damage after stopping, convert F6, F8, F2 manual control. H: Y belonged to the water pump, the water in pool. After downtime prevent loss of water by the water pump to water use. To their relief after water H has not been dismantled.

2, pressure reducing valve, there existed some problems at the pearl of

secondary plant since 2006, P2 multiple occurrences of working condition is not stable. The low into the unit pressure is only 0. 02 mpa, far can not meet the requirement of the technical water supply. Plant only has a set of artesian pressure water supply system, no spare water supply system. To ensure the safe operation of the unit form great threat.

3, on-site inspection:

because water quality is poorer, because the original copper valve valve core and there is a size 6 mm x 8 mm abrasion, affect the control valve regulating ability.

field replacement for stainless steel valves. Adjust the P2 to 0. 4 mpa, P2 stability obviously. But will from time to time pressure drop to zero. 18Mpa~0. 19Mpa（ The callback) 。

4, root cause analysis:

P2 significantly lower than the set pressure, only 0. 02MPa。 After new control valve, pressure from 0. 02 ~ 0. 4 mpa is adjustable. Prove that the pressure control valve can be normal conduction through feedback system to the main valve cavity voltage regulator, pressure reducing valve regulating function is normal. Change the pressure reducing valve (P1, P2 and stability. Feedback system can be adjusted automatically according to the change of outlet pressure of main Industrial Valves cavity pressure, forces the pistons to change the throttle opening of the cone, pressure reducing valve automatic pressure regulating function is normal.

the problem is that when the pressure reducing valve P2 adjusted to zero. Cannot be stable after 2 mpa, run after a period of time pressure will fall.

in the operation of the pressure reducing valve (P1 to 2. 16 mpa, found after decomposition pressure reducing valve, cylinder liner piston position have to the end. And flexible piston within the cylinder liner motion of the opening of the throttle cones have enough. Although no pressure gauge pressure reducing valve P2, according to the throttle opening of the cone is still can judge the porv have enough pressure and flow rate, thus eliminate pressure reducing valve failure.

5, check the water supply system:

check valve before and after the water supply piping system of technology on each valve, each ruled out after each valve in the pipeline. Judgment between exports and water filter for pressure reducing valve, silencing the problem of slow close check valve. As shown in figure 2.

6, check the H:

remove the dead slow close check valve. Body disc, pooling a large number of impurities, severe pipeline ( See figure 3) , reduced the pipe flow area, equivalent to the technical water supply system for the secondary stress. Because of the serious congestion, reduced the water supply pipeline flow area, so lead to insufficient pressure into the unit before the P2.

7, Suggestions to plant:

, we have to plant modification Suggestions are put forward. 1, remove the dead slow close check valve internal disc, change the pipeline to direct. 2, remove the dead slow close check valve on the policy type Industrial Valves, pressure gauge.

in our joint efforts, with power plant on March 23, 2008 to complete the transformation of the technical water supply system for the secondary station.

after the completion of the transformation ( See figure 4) And into the unit pressure stability returns, P2 reached 0. 35MPa（ Adjustable) , change the P1, into the unit pressure stability. After 24 hours test run, the technical water supply system can reach the standard unit operation. Reform success.

8, epilogue

this maintenance let pearl secondary technical water supply system for power plant to restore stability, to transform to eliminate the unit operation of the pipeline system of serious hidden dangers. To ensure the safe operation of the unit, and embodies the quality of the company to plant was impressed.

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