Abstract: In view of the problems such as the sediment intake at the water intake, the sediment in the wellbore, the short life of the deep well pump, and the instability of the water inlet valve during the operation of the deep well pump station with high water content, the corresponding solutions are proposed and comprehensively managed Improve, and achieved good results.
Key words: high silt water; deep well pump station; comprehensive treatment
The deep well pumping station of Panzhihua New Steel-Vanadium Company Power Plant is located beside the Jinsha River. During the flood period, it takes the company-wide production and water extraction tasks. The layout of its facilities is shown in Figure 1.
Four DN1200 diversion pipes were used to introduce the river water into two wellbores with a diameter of 18m and a depth of 30m. Ten 30JD-19 * 3 long shaft deep well pumps (Q of 1440m3 / h, H 800kPa), to high water into the water treatment plant. Sands of the Jinsha River in the flood period of sediment up to 24kg / m3, of which 0.1mm above the grain size of more than 30% of the coarse sand, while a large number of slag slag upstream site also downstream down to Sham Tseng pumping station water Mouth, the deep well pump station is put into operation one month later due to sand and paralyzed state, a serious threat to the second phase of Panzhihua Iron and Steel production.
1, the intake of sediment (slag) treatment
In the first flood period after the operation of the Sham Tseng pumping station was put into operation, the water outlet was dilapidated within a few days. According to the analysis, it was found that the water intake was located in the siltation zone due to the shape of the upstream convex mouth and the river channel. The solution is as follows:
â‘ blow up the upper part of the convex and reef rocks and cut off the left side of a slope, the main purpose is to make the upper stream of water around the flow of the convex and reefs tend to bias the left bank where the intake to speed up the flow at the intake to Reduce the sediment deposition in the area;
(2) Dredging the riverbed near the water intake to make the shape of the riverbed consistent with the flow and velocity of the river, reducing the siltation as much as possible, and at the same time the riverbed and water intake after the desilting have a certain elevation difference, so that " ";
③ In the other side of the water intake to build a digging Dingba, the angle between its axis and the right bank of 60 °, the crest elevation of 995m (intake elevation of 990m), the dam length of nearly 80m, forced dam of the dam so that the main flow of the river The left bank where the water intake is located.
After the implementation of the program, no serious siltation accident occurred in the riverbed adjacent to the water intake, and basically no siltation or erosion was achieved.
2, the treatment of sand in the wellbore
After the water enters the wellbore from the diversion pipe, coarse sand and slag will be quickly deposited due to the greatly reduced flow rate, which will result in the siltation of the wellbore. Only by manually dredging the sand can sustain production. In this regard, the following measures have been taken:
â‘ increase the water intake
During the flood season, when the water level of the river rises, the amount of sediment (sediment) in the upper water is relatively large, while the amount of sediment (slag) in the lower water increases when the flow and level of the water drop down. Therefore, the upstream wellbore elevation is 994 m, Lower wellbore elevation 995m at the water level increase in the water intake and water intake in the installation of a hole diameter <14mm steel filter to prevent the particle size> 14mm slag into the wellbore.
â‘¡ additional special sand brake
In order to eliminate the sand at the dead angle between the water diversion and the water absorption, a method of reducing the density of air, water and sand (air phase, liquid phase and solid phase) Compressed sand trap (see Figure 2), as long as the water level increases and maintain a certain submergence ratio (sediment height and water level height ratio), even if the particle size of about 30mm slag can be discharged. Install 5-6 gas ballasting devices in the dead ends and the sediment-laden area of ​​each wellbore. At the same time, build an air compressor station and corresponding gas pipelines, drainage pipes and ditches.
â‘¢ Increase backflushing system at the bottom of the well
In the easterly area and the lower part of the pump head to install pipelines and set a certain number of different angles of the nozzle, when the sediment reaches a certain level (obtained by measuring the sand bit) that access to high pressure water in the pipeline, nozzle spray Out of the water agitated sediment, sediment can be discharged by the following methods:
a, deep well pump away
b, the wellbore water level increased to a certain extent (external filling) and suddenly open the water valve, the wellbore water and sediment under the pressure of the cis-tube back flush into the river;
c, a special row of sand drain.
3, the transformation of some of the equipment
Due to the wear and clogging of sediment, it also resulted in short service life of deep well pump (the average operating life is only about 3000h) and DN1200 water diversion butterfly valve is not closed properly.
â‘ deep well pump
After analysis, radial rubber bearings along the drive shaft (8) is easily damaged is the root cause of short life of deep well pump.
Radial rubber bearing damage in two ways: a. Bearing cooling water pipes are often broken, because underwater can not be easily found, so high-pressure cooling water can not enter the rubber bearings, which not only makes the bearing can not get hot Cooling, but also with a lot of sediment of the river will enter the bearings to speed up the bearing wear; b. Rubber bearing wear to be improved.
Due to the rigid connection of the cooling water pipes of the rubber bearing, the stress concentrated parts will be broken due to fatigue, therefore, the water pipes are replaced with high-pressure rubber hoses. In addition to ensure that the radial bearing wear resistance, to transform it into a composite of two materials (bearing contact with the inner ring made of filled polytetrafluoroethylene, the outer ring made of rubber), so that both radial bearings The toughness also ensures its wear resistance, but also reduces costs. Improved pump life reached 10000h or so.
â‘¡ water butterfly valve
In the diversion pipe installed four DN1200 diversion butterfly valve. Butterfly valve rubber seals easily fall off and can not be replaced due to the valve installed in the water, the other easy to be the valve plate debris and debris stuck in the water there is the problem of lax closure. To this end to replace the valve butterfly valve for the diversion valve, taking into account the valve can only be closed effectively function, so the valve plate just below the body to open a square hole 200mm × 960mm and are divided into four grid, so that the sand (Slag) into the well through this hole will not be deposited here, in addition to the central body of the valve into a high-pressure pipe (also accessible through the compressed air) to flush this hole to wash away the sediment and will not affect the closure of the valve .
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