Improved n300mw unit high pressure regulating valve fault handling

Author: Xiao Wu Xuebin peaks Abstract: Daba Power Generation Limited Liability Company # 2 # 4 high-pressure steam turbine operation regulation problem Valve diffuser loose, to loose the reasons were analyzed, and processed by unit maintenance, such proposed The solution of the problem, to ensure the safe operation of the unit. 1 Introduction Daba Power Generation Co., Ltd. # 2 steam turbine is made by Shanghai Steam Turbine Co., Ltd. Domestic modified n300-16.5 / 535/535 type subcritical, intermediate reheat condensing type, single-axis four-cylinder four-row steam condensing type Turbine. There are 2 high pressure main steam door, 8 high pressure regulating valve, 4 medium pressure joint valve. Adjustment method for the digital electro-hydraulic control system (deh-v), 300mw load # 1, # 2, # 3, # 4 high-pressure regulating valve is fully open state. 2 fault conditions February 20, 2006 8:00 am, maintenance personnel in the process of inspection equipment, # 2 steam turbine # 4 high-pressure regulating valve to hear the interval noise, but when the relevant professionals came to the scene , Abnormal noise did not appear again. At about 13:55 on February 21, the maintenance personnel again heard the abnormal sound of # 2 steam turbine # 4 high-pressure regulating steam valve during the inspection of the equipment and immediately contacted the relevant professionals to confirm the difference Tone from # 4 high-pressure regulating valve, combined with the same type of unit has occurred defects and high-pressure regulating valve internal structure, the initial judge abnormal sound is due to high pressure regulator valve diffuser loose. Reported the leadership of the company will # 4 high-pressure regulating valve closed to avoid the diffuser after the release of high-profile door diversion bell break the accident. 3 Reason Analysis This type of unit high pressure regulator valve diffuser is fitted on the valve body with interference fit. Manufacturers in the initial design and installation instructions required interference is 0.06mm ~ 0.09mm, and between the diffuser and the body plus a f20mm horizontal pin reinforcement. However, due to the change of steam parameters in actual operation, both the diffuser and the valve body are subjected to an alternating thermal stress, and the force generated by the high-speed steam flow in the diffuser causes the diffuser to loose during operation. This type of turbine is designed and produced by Shanghai Steam Turbine Co., Ltd. It is limited by the technical conditions and operation experience of 300mw unit at the time. Due to the lack of tightness of the diffuser, the looseness of the high pressure regulating valve diffuser is ubiquitous and Simply unable to deal with the operation. After shutdown, due to the decrease of the temperature, the diffuser is tightened again after the valve body is cooled down, which makes it difficult for maintenance personnel to confirm the looseness of the diffuser. Dam Generation Co., Ltd. with the same type # 1 steam turbine high pressure regulating valve also had similar problems.