Created on:2021-09-06 10:32

Hydraulic fault diagnosis and maintenance of port equipment_ Hydraulic system failure of wharf loading bridge

Hydraulic fault diagnosis and maintenance of port equipment_ Hydraulic system failure of wharf loading bridge

The 35000 ton coal wharf of a power plant is equipped with two 1350t / h shore loading and unloading bridges, with an annual coal unloading capacity of about 2.5 million tons. The two loading and unloading bridges are respectively equipped with a set of the same hydraulic station. The grab lifting and opening and closing of the loading and unloading bridge, the clamp brake of the girder and traction trolley and the rail clamp of the crane are powered by the hydraulic station, and its oil circuit is shown in Figure o.

O.jpg

(1) Fault phenomenon

The brake of No. 1 loading and unloading bridge often fails to open during operation, which has a great impact on the operation of the equipment. After inspection, the mechanical part of the brake is free of jamming and operates flexibly; The working oil temperature of the hydraulic pump station is about 75 ℃, while the maximum temperature during normal operation shall be lower than 65 ℃. Initially, it was suspected that the oil quality did not meet the requirements or the solenoid valve was damaged, but no problem was found through oil quality test; The hydraulic pump station was cleaned and the solenoid valve was replaced, but the fault still existed.

(2) Diagnosis method and process

Several solenoid valves 12 in the hydraulic system are arranged on the same solenoid valve block 8, so it is difficult to measure the reasons for the high oil temperature of each solenoid valve respectively, and there is no hydraulic calibration equipment at the work site, which brings inconvenience to the maintenance work. For this purpose, the following test methods are used.

① Test the pump station of No. 1 loading bridge. Stop the working mechanism and idle the hydraulic pump station for 2h. During this period, use the infrared thermometer to test the temperature rise of oil tank 1, hydraulic pump inlet (oil filter 2), hydraulic pump body 3, oil return pipe 4, pump outlet (oil filter 6) and solenoid valve block 8 in Figure O, record and draw the temperature rise curve. In the No. 2 loading bridge pump station without failure, the test shall be conducted for 2h according to the test form of No. 1 unit, and the temperature rise curve shall be drawn.

② Comparing the temperature rise curves of the two tests, it is found that the oil temperature rise speed of the hydraulic system of unit 1 is significantly faster than that of unit 2, and the oil temperature of unit 1 still shows an upward trend after 2h, while that of unit 2 tends to be flat. The two test temperatures at the beginning and 2h after the end are shown in Table 1 below.

 

Table 1 oil temperature test items before modification

Test items

1号机/℃

2号机/℃

油箱

起始温度

26

28

终结温度

63

38

  液压泵

  进口

起始温度

25

28

终结温度

65

35

液压泵

起始温度

34

33

终结温度

74

49

  回油管

起始温度

29

30

终结温度

64

43

  液压泵

  进口

起始温度

25

28

终结温度

54

38

  电磁阀块

起始温度

22

28

终结温度

25

31

测试时环境温度

22

28

 

Table 2 test oil temperature after replacing hydraulic pump

测试项目

1号机/℃

2号机/℃

油箱

起始温度

23

21

终结温度

35

59

  液压泵

  进口

起始温度

23

21

终结温度

35

62

液压泵

起始温度

36

30

终结温度

50

73

  回油管

起始温度

31

27

终结温度

44

60

  液压泵

  进口

起始温度

25

23

终结温度

36

47

  电磁阀块

起始温度

22

21

终结温度

25

24

测试时环境温度

22

28

 

(3) Analysis of test results

The temperature rise at the solenoid valve blocks of the two hydraulic systems is only 3 ℃, which indicates that there is no internal leakage at the solenoid valves and maintenance valves when the working mechanism does not act and the two pump stations are idling.

The temperature rise at the hydraulic pump of unit 1 is the fastest. It is preliminarily confirmed that there is internal leakage in the hydraulic pump of unit 1, causing heating.

In order to further verify the cause of the fault, the hydraulic pumps of the two loading and unloading bridges were replaced, and the temperature rise everywhere was tested under the same conditions. It was found that the temperature rise of unit 2 was significantly higher than that of unit 1. The two test temperatures are shown in Table 2 above.

It can be concluded from the test results that there is internal leakage in the hydraulic pump of the original unit 1.

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