At present, the domestic thermal power plant water pump bearing oil leakage problem is widespread. Analysis of the reasons can be broadly divided into two kinds: the motor oil seal poor or oil seal damaged by long-term operation; the original casting bearing box due to poor casting process, the existence of trachoma, porosity, cracks, shrinkage casting defects, after long-term operation occurred leakage.
(1) Existence problems A power plant 8 #, 9 # unit electric feed pump motor bearing housing, after long-term operation of the oil leakage phenomenon, the turbine oil loss is more serious, frequent filling, to the pump output affected, The environment is also polluted to some extent.
(2) Analysis of the causes The 8 # and 9 # generating units of the power plant are two old units put into operation respectively in 1985 and 1990. The bearing housing of the water pump and motor pump is cast and inevitably have blisters, pores, cracks and shrinkage Other defects. In the past these shortcomings could not be exposed very quickly because of the short run times, and oil leakage into the pump motor bearing housings occurred after 10 or even 20 years of operation.
(3) Improve program Refer to a large amount of relevant information, formulate this program based on the full investigation and research and combined with the actual situation on site. HT series using the domestic back to the days of production of HT products for leakage coating treatment, casting defects due to leakage, it is generally difficult to confirm the location of leakage, so the entire inner surface of the anti-seepage coating to completely eliminate leakage . Operation flow is as follows: First, clean the inner surface of the bearing seat to clean and dry, and then impregnated with special impregnated bearing housing cavity impregnated plastic will be casting cracks, micro-cracks and other casting defects fill curing, reuse Anti-corrosion repair agent outer anti-corrosion anti-seepage treatment.
Specific methods of operation are as follows.
â‘ first use high-performance cleaning agent HT755 oil slick surface, remove the surface paint with a scavenger HT790.
â‘¡ acetylene flame will be dead ends, cracks in the oil drive out get rid of.
â‘¢ with emery cloth, wire brush and other tools polished to the casting body, clean and dry.
Etc .; the upper bearing (deep groove ball bearing) is not bad; the lower bearing is fragmented and filled with cinder, sand and water in the bearing and bearing cavity.
The analysis shows that: the bearing life is longer than the lower bearing, the lower bearing fragmentation lead to the pump can not work; the lower bearing and bearing cavity is full of cinder, sand and water is the next and the rapid failure of the main cause of the rapid failure; lower bearings and bearings Cavity filled with cinder, sand and water from the motor chamber, the motor cavity cinder, sand and other sources of water from the condition, because the skeleton oil seal wear 5,10,14 failure.
(4) the solution of the problem
In view of the above analysis, a QS20-75 / 5-7.5 deepwater deep well pump was modified and improved in October 2002. The improvements are as follows: Skeleton Oil Seal 5 The single-end mechanical seal is modified to prevent water and other debris from entering the motor cavity Bearing, accelerated bearing wear failure; bearing cavity filled with oil 7, the purpose is to lubricate the bearings, lubrication and cooling mechanical seal to improve the working environment for the next bearing. The improved prototype was put into use in a coal mine test on October 15, 2002. The first fault occurred for 75 days in total operation - the upper bearing was broken, the coal mine failed after 30 days of replacing the bearing, and then the prototype was pulled back to the factory . The first life is 2.5 times the original, was initially successful. The inspection found that: the motor is good; the shaft is willing to crack and filled in the bearing and bearing cavity cinder, sand, etc .; skeleton oil seal 2 serious wear and tear, cinder, sand is from the oil seal and shaft clearance into the upper bearing The cumulative bearing used for 105 days (3 ~ 4 times before improvement) was intact. There was no cinder and sand in the bearing cavity and a small amount of water in single oil.
As a result, the problem translates into how the life of the upper bearing is extended to match the lower bearing. Because the lower bearing problem has been solved, the life of the bearing on the solution to the problem of using a similar program; skeleton oil seal 2 can be modified into a single-end shaft mounted mechanical seal to prevent cinder, sand and other access to the upper bearing, improved bearings The working environment to improve their life expectancy.
(5) Summary Since February 2003, more than 70 improved QS pumps have been put on the market, which are mainly used for drainage of deep wells and drainage of mines in the occasion of use. They are the longest used ones Up to 5 months, so far only one failure, but not a bearing problem. In accordance with this method can indeed solve the QS submersible pump bearing life issues.
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