Analysis and treatment of large amount of hydraulic gate opening in Hydropower Station

A hydropower station RCC arch dam layout four hole spillway, radial gate by the 4 2/80t hydraulic hoist drive. Hydraulic sand bottom working arc gate hoist is 1*63t, hoist room and control room are located in the.

1. hydraulic hoist status

The hole table by the hydraulic hoist hydraulic station, control valve group, two 80t hoist cylinder and electric control parts, 1, 4, 3 and 2 gate gate every two backing up close machine sharing a hydraulic station. Bottom hole hydraulic hoist control valve and electric control system of independent hydraulic station. The hydraulic pump assembly of the hydraulic station is ready for use, and the control valve set adopts a two position cartridge valve.

Hoist without special hydraulic locking unit, using two cartridge valve group is used as a hydraulic lock, the hoist on the early operation is more effective, but the use of a certain period of time and the number of times after the valve locking effect will decrease due to wear; in addition, valve installed in the control room when the gate lifted to the gate position after the pipeline to the reversing control valve group from the hydraulic cylinder has been in a state of high pressure, if the line is damaged, the hydraulic cylinder rod chamber oil leakage, gate quickly closed, under the action of gravity control, in the flood season in the flood gate dead; is not allowed in this accident, so must add the hydraulic cylinder hydraulic locking unit. Headstock two hydraulic cylinder synchronous control for manual, is an early product.

2. headstock fault phenomenon and inspection

(L) hoist fault opening and closing function normal opening and closing the gate, but to work after a high lift gate cannot lock the gate, there are different degrees of decline in the larger problem, 24h fell a larger amount than 1m, 24h decline in the maximum amount of up to 2. 4m, which exceed the standard, can not be used.

(2) hoist machine fault check, carefully check the appearance of headstock, hydraulic cylinder, valve group, pipe network are not found outside the oil spill phenomenon. The disintegration of the hydraulic cylinder, hydraulic cylinder piston ring there are different degrees of wear, flanging, curling, missing edges and fracture damage, there is no good, especially the bottom hole of hydraulic hoist cylinder piston seal completely crushed aging damage. The support rings of each hydraulic cylinder also have certain wear and tear, the parts of support rings are seriously out of size, and the maximum clearance is O.75m. And the cylinder wall of each hydraulic cylinder has varying degrees of pull, strain are distributed in the working position of the hydraulic cylinder, cylinder below, there is a certain law. The most serious length of about 6m, width of about l0cm within the range of obvious scattered stretch mark; hydraulic cylinder tail cylinder has a certain degree of corrosion; plug valve, the valve core sealing cone has certain wear.

Cause analysis of 3. hoist failure

The opening and closing function of the normal opening and closing the gate, control valve group and hydraulic station each function is normal; the gate opening fell after serious exceed the standard, open and close that there is severe leakage of hydraulic system; no leakage phenomenon that exists in the leakage of the hydraulic hoist system within the department. According to the fault phenomenon and inspection analysis, the leakage position should be in the hydraulic cylinder and control valve group.

(1) the leakage of hydraulic cylinder is due to the long running time of the hoist. The damage of the seal ring and support structure, the damage of the hydraulic cylinder and the aging of the cylinder and the inner wall pulling of the cylinder are the main causes of the leakage in the hydraulic cylinder. The gate was promoted and locked to the gate position, the hydraulic system to stop working, the hydraulic cylinder out of the oil channel is cut off, the hydraulic cylinder rod chamber under the action of self weight gate will establish a P0 hydraulic rodless cavity volume increase tendency, hydraulic relative low P0, the two oil chamber will form a pressure poor. When the sealing structure of the two chamber of the hydraulic cylinder is damaged, the oil leakage from the rod chamber to the rod cavity can be formed under the action of differential pressure. There is rod cavity hydraulic oil leaking into the rodless cavity. With the decrease of the chamber volume and the downward movement of the piston, the gate appears to slide under dead weight. The leakage of the two chamber of the hydraulic cylinder caused by the sealing structure of the hydraulic cylinder is characterized by the leakage in the hydraulic cylinder. The piston seal ring is damaged, the inner wall of cylinder is pulled out and the piston support ring is seriously worn, and the pressure oil leakage path is formed between the two cavities of the hydraulic cylinder, which results in the leakage of the hydraulic cylinder.

(2) the system leaks the headstock to lift the gate to the gate position, and the hydraulic cylinder uses the two position cartridge valve to lock the cone surface. Two there will be a certain amount of cartridge valve heart valve cone many times after wear; heart valve cone side rod pressure oil, the oil pressure is higher, the other side of the oil return channel, oil pressure is zero; under differential pressure, the hydraulic cylinder rod chamber pressure oil will leak back through wear the oil tank, the formation of system leakage, the hydraulic cylinder rod chamber volume decreases, the piston moves down, as the gate down.

(3) the leakage of hydraulic cylinder and the leakage of the system exist in the hydraulic hoist which is in disrepair and large amount of decline at the same time. The common hydraulic cylinder leakage and system leakage exist simultaneously. There are two kinds of leakage in headstock gear, mainly leakage in hydraulic cylinder, auxiliary leakage of system.

It is worth mentioning that the dispersion ratio, cylinder leakage and system leakage also exist in the door opening and closing process, which directly affects the gate opening speed, the synchronization of the two hydraulic cylinders and the stability and safety of the gate operation. When the leak develops to a certain extent, the hoist will not work, even sudden fault occurs.

4. renovation and maintenance measures of headstock gear

According to the existing hoist system for hydraulic cylinder leakage and leakage caused by the decline in the gate, additional hydraulic cylinder hydraulic lock system, solve the problem of leakage, and improve the hoist safety; replacing the hydraulic cylinder of the hydraulic cylinder seal and all necessary for proper maintenance, and solve the problem of leakage of hydraulic cylinder.

(1) a hydraulic lock for hydraulic cylinder is added, and a hydraulic locking unit is additionally arranged at the oil inlet pipe at the outer wall of each hydraulic cylinder, and the hydraulic locking unit is fully operated by the hydraulic control. When lifting the gate, the pressure oil opens the hydraulic lock automatically, enters the hydraulic cylinder, has the rod chamber, the lifting gate. When the gate to set the gate position, the hydraulic system of the hydraulic lock stop feeding, automatic locking hydraulic cylinder rod chamber oil, ensure the hydraulic cylinder rod chamber pressure oil leakage, solve the hoist gate caused by the decline in the system leak. At the same time, ensure that the pipe network outside the hydraulic cylinder is in the state of non pressure, improve the operation environment of the pipe network. When the pipe network is damaged, the hydraulic cylinder has rod cavity, the hydraulic oil will not leak out, the gate will not slide, greatly improving the reliability and safety of the hoist and gate operation.

(2) the treatment measures of leakage in the hydraulic cylinder were analyzed. The 3 main causes of leakage of hydraulic cylinder sealing ring is damaged, the inner wall of the cylinder barrel supporting ring strain, serious wear, according to different problems by using different measures.

1) to replace the sealing ring replacing all hydraulic cylinder rod and piston seals, all end fixed seal; in a supplement to the original sealing cylinder tail fixed seal, to prevent rainwater into the hydraulic cylinder caused by hydraulic cylinder rear cylinder corrosion.

2) coping measures for inner wall of cylinder barrel. In the field, special equipment is used to carry out cloth grinding on all the inner walls of the hydraulic cylinder and cylinder, and the inner wall of the cylinder can be completely eliminated and rust removing and decontamination can be carried out. The process for proprietary technology, need special equipment and the corresponding technology and experience of the staff to carry out improper use will cause loss of circular cylinder wall, forming taper irreparable damage; also control the amount of cloth grinding according to the specific situation of each hydraulic cylinder, cloth grinding overload will cause the inner diameter of cylinder with size error cloth, grinding amount is too small and can not solve the problem, so the process must be careful to use.

3) support ring wear treatment measures. The selection of the site all the supporting ring and the piston, select reasonable tolerance group with direct use of the ultra poor; the support ring is not serious, the copper plating process on piston to compensate the size deviation, the tolerances in the reasonable range of the loss of large size; the support ring and the piston to ensure its re processing with the size, to meet the use requirements.

(3) the reversing valve group handles and changes all the damaged parts and seals, ensures its reversing function, and does not pursue its unreliable hydraulic locking function.

Other parts are processed according to conventional process.

5. use effect after renovation

After renovation and maintenance, the functions of opening and closing are normal, opening and closing gates, door opening and door closing are running smoothly. Gate 48h and 60H high locking down are much smaller than GB requirements, as shown in table 19-3. After the maintenance of the hoist, it has experienced the flood test in the 2001 flood season, completely restored the original work performance, and the quality of maintenance is excellent.

The large amount of sliding behind the gate of hydraulic hoist is caused by leakage, and the leakage of hydraulic cylinder is the main reason. When the leakage of hydraulic cylinder develops seriously, the opportunity of opening and closing appears. After the gate is opened, the gate declines greatly, the gate cannot be locked high, and it can not even open the gate.

Hydraulic hoist maintenance complex, long construction period, the flood season can not organize emergency repairs, must be completed before the flood season.

Hydraulic hoist is a precision equipment, maintenance must be made before the detailed maintenance program, ready adequate equipment, tooling. Repair do not be rough, remove the light light, do not use the hammer tools such as forced disassembly, for civilized construction.