In Shenhua Guohua Mengjin Power Generation Co., Ltd., the first phase of the 2×600MW supercritical coal-fired units officially started construction in April 2008. #1&2 units started commercial operation on March 1, 2011 and August 27, 2011, respectively, after 168 hours of trial operation. Since its operation from 2011, the #2 unit has been in good operation condition.

Yet in August 2013, #2 boiler A induced draft fan fluid coupler suddenly had high bearing temperature, large vibration and lubricating oil leakage. The hydraulic coupler was imported from Germany VOITH, having no speed-increasing gear, with the induced draft fan directly driven, and the single input power above 5000KW, which was rare in China. The Plant contacted the manufacturer, who responded not to provide on-site maintenance and requested to send the coupler to Shanghai Repair Center, which could cost 3 months, RMB 400,000 maintenance fee and RMB 100,000 transport cost.

Our experts from the rotating equipment fault diagnosis center went to the Plant for precision diagnosis on the coupler in December, discovering that the equipment bearing bush had lubrication problems, and thus proposing a detailed site maintenance plan, which was ratified by the leaders and technicians of the Plant. In January 2014, in the interval of minor repair of #2 unit, the Plant decided to dismantle, maintain and repair the faulty coupler according to BKC's plan.

BKC sent six skilled hydraulic coupler maintenance experts to the site and spent 15 days successfully processing the fluid coupler fault. The trial operation was satisfying and so far the fan has been working normally. The maintenance cost is RMB 50,000, saving RMB 450,000 for the Plant if maintenance conducted by Shanghai Repair Center. In terms of time consuming, we completed the maintenance 2.5 months earlier, assuming the profit is RMB 0.03/KWH, the extra benefits from power generation would be RMB 32.4 million.