Do you know VV valves and application performance of BDV valves?

There are many kinds of valves, the use of performance and features are also different, for VV and BDV valves many users is not very understanding, here introduces the knowledge of the VV and BDV valves. A, BDV valve: called turbine dump valve. Unit of high pressure cylinder, when the unit load rejection, in order to prevent the high pressure cylinder, high pressure steam pipe of steam pressure seal clearance from high school went to the middle pressure cylinder, the low pressure cylinder, harmful to the unit. If these seal tooth wear and seal clearance greatens, causing the unit increases the possibility of speeding, set for the dump valve ( BDV） 。 When the unit trip, BDV valve rapid opening, more than at high pressure steam gland steam directly led to the condenser, prevent a speeding. Dump valve open and close by the medium voltage regulator oil motive trip to control: oil pressure regulator motives of travel & ge; 30 mm, dump valve shut. Oil pressure regulator motivation of travel & lt; 30 mm, dump valve to open. Electromagnetic control valve when the excitation, the compressed air into the dump valve piston, piston to overcome the spring force down valve close to death. Electromagnetic control valve excitation-loss, dump valve piston top and exhaust are interlinked, drain off the air pressure, piston under the action of spring force, move up open the valve. Second, VV Valve means: Vent Valve. When using intermediate pressure cylinder starting and low load operation, the high pressure cylinder is not into vapor or steam quantity is less, high exhaust non-return door closed. This kind of situation will cause high pressure stage blade overheating due to friction blast. Therefore, in the high pressure cylinder exhaust pipe is installed on a ventilation valve, direct access to the condenser, maintain the vacuum in the high pressure cylinder. In addition, the steam turbine trip, the valve opens automatically, makes the high pressure cylinder steam quickly into the condenser, prevent because of the high pressure steam pressure cylinder shaft seal leakage through high school into the intermediate pressure cylinder ( The intermediate pressure cylinder for vacuum) The rotor speed. V. v. valve controlled by an air door, automatic action. The upper valve for a cylinder, the loss of air pressure, under the effect of spring, the upward opening; Electromagnetic valve electrically charged, truncation gas source, VV valve open; Electromagnetic valve when losing electricity, turn on the air, the air piston compression spring, VV valve shut down. 1, prevent during normal operation due to high exhaust non-return of the opening of the door is not enough, exhaust temperature is too high, can open the vent valve. Even open the air valve during downtime, make the HP cylinder steam off quickly. 2, in the middle pressure cylinder startup, high pressure cylinder inlet, can open the vent valve take high pressure air in cylinder, reduce friction drum wind. 3, the initial high steam parameters of low exhaust non-return door open, with ventilation valve provides pathways for steam, steam into thin expansion. Grid after open the non-return after 1 minute, close the vent valve. 4, at low load operation, prevent friction blast, the exhaust temperature is too high, or high pressure than low jump machine.