FengNing pumped storage power station valve seal function analysis

FengNing pumped storage power station valve seal function analysis shows that 2019 - 07 - 24 Zhang Fang Yao Wenge ( Harbin electric co. , LTD. ) 【 Abstract 】 Hebei pump turbine FengNing pumped storage power station, power electric unit by Harbin electric co. , LTD. Independent design and manufacturing. Plant rated head is 425 m, before the turbine is equipped with a diameter of 2. 35 m of ball valve. FengNing power station are presented in this paper the characteristics of the pressing function of ball valve, ball valve, sealing structure and sealing material, and ball valve sealing ring structure is analyzed. 0 foreword pumped storage power station are introduced in this ball valve of the pressure function, as well as FengNing power station off a by-pass pipe used in sealing after pressing, to plan as a whole to consider the strength of ball valve and sediment content, self-excited oscillation, just, material, structure, performance, etc. , analyze the function of valve seal. 1 ball pressing function of pumped storage power plant water quality generally good, sediment concentration is low, a machine in front of the roller ball valve open also can by open the ball valve of the main seal, do not use the by-pass pipe, by-pass valve used only to eliminate possible self-excited vibration, under normal circumstances can remain closed. Self-excited vibration causes may be due to the work seal the sealing ring or seal on the sliding surface is damaged, make the sealing work produces reciprocating motion, the consequences are sealed cavity and pressure steel pipe of abnormal pressure rise. To eliminate self-excited vibration, sealing pipe operation and standby operation can be water, will the pressure inside the pressure steel pipe drain off. Therefore, by-pass line not eliminate self-excited vibration will choose equipment. FengNing rated head hydropower station is 425 m, ball valve design water head of 762 m, belongs to the high water head pumped-storage power station, if the vibration of the by-pass pipe is too big, the safe hidden trouble that will burst. Some has run for years of pumped storage power plant, such as pine and power station, xiangshui jian, are sealed with work pressure, and have had a good run. Therefore, the current FengNing ball valve cancelled the by-pass pipe, using work sealing pressure. 2 ball valve seal is introduced. 1 seal structure of ball valve seal including upstream side maintenance work with the downstream side, are removable type structure, composed of stainless steel ring and stainless steel fixed seal seat respectively, the fixed seal seat with stainless steel screw on the valve, sealing ring for the overall structure, designed to slide, after the ball valve closing seal sliding pressure to the fixed seat, leave the fixed seal seat before opening. The body sealing ring on the guide surface USES the aluminum bronze alloy lining protection, sealing ring in combination with sealing ring, is composed of high hardness polyurethane ring and O ring. The sealing structure is shown in figure 1. Sealing principle is to use the sealing ring in operation under the action of water pressure to produce elastic deformation, and the deformation of the valve seal seat to compensate, and generate hard contact, to achieve sealing effect. Sealing ring and sealing socket interface USES the conical surface and spherical structure, which can effectively reduce water leakage, ensure the sealing performance. Seal for T type structure, the size of the slip plane with the sealing ring can guarantee repair resistant open self-locking function and the working seal ring under various conditions of normal. 2. 2 sealing material of the ball valve seal and general selection according to material performance, selection was based on sealing surface contact stress is smaller than the material yield limit, according to the ratio of yield limit and sealing surface contact stress ( Safety margin) For judgment. For ZG06Cr13Ni4Mo FengNing ball valve sealing ring material, the yield limit of 550 mpa, sealing material for forging steel 06 cr13ni5mo, the yield limit of 620 mpa, in a sealed into the cavity and the upstream water pressure for the biggest hydrostatic pressure 5. 27 mpa, the upstream and downstream side seal and the safety margin of not less than 10 times, meet the design requirements. As shown in figure 2 and figure 3. 2. 3 ball valve sealing ring structure FengNing sealing ring on the seal ring is composed of polyurethane rings and o-rings. Seal design to comprehensive consideration of sealing material, the size of the seal face with, sliding surface material, machining accuracy, the design pressure and body deformation factors, according to the seal manufacturer recommendations, FengNing sealing ring on the combination sealing ring, by the high hardness, wear resistance of polyurethane rings and o-rings, this seal structure of large amount of compensation, sealed performance is good, can satisfy the ball valve sealing surface with sizes and different conditions of use requirement. Conclusion FengNing ball valve selection of sealing material has enough safety margin, the choice of sealing material is reasonable, the structure and form can satisfy the normal cast back and sealing performance during overhaul, the sealing roller can ensure the service life of sealing during the overhaul period work, to guarantee the safe and stable operation of unit. Source: 'China's new technology and new products, 2018, 12