Automatic Cheese Vacuum Packaging Machine hangzhou mankun imp. exp. co., ltd. , https://www.multihzmachine.com
In the thermoelectric industry, the use of control valves is rather special. In simple terms, the power flow is only the circulation of water and steam. However, selecting the control valve in this process is simple and complicated. Simple is the process medium is simple, only water and steam two kinds of complicated water and steam temperature and pressure fluctuations range, bringing a series of problems such as: flash, cavitation, erosion, noise, corrosion. But the first thing to consider is the safety and reliability of the control valve. 1, the water supply valve (main, with the boiler feed valve, water supply control valve) Control requirements: control of boiler water, to ensure that the amount of steam evaporation, to maintain the water level of the boiler (main and auxiliary boiler feed valve system contains two control valves, one Taiwan is used for boiler start-up, one for normal water supply. Working conditions: When the boiler is started, the pressure drop of the valve can reach 100-300 kg, the flow rate is smaller, the pressure difference is smaller during normal operation, the flow rate is large, the flow rate can be The ratio is 75: 1 ~ 100: 1. Valve requirements: WCB / WC9, for the two-valve system requires anti-cavitation valve start-up, V-level shut down for complex water supply valve to be used to meet the characteristics of the valve trim at the same time Boiler start-up and normal operation of the need for the general valve selection for the fault off. 2, the minimum flow pump feed pump valve control requirements: the boiler feed pump start and stop running safely, eliminating the flow is too small, increasing the temperature, water is intense Cavitation damage to the pump. Old-fashioned power plants have the use of switch-type minimum flow control valve, as well as the use of mechanical pump automatic cycle valve. Conditions: pressure drop of 160-350 kg, is Valve system to withstand the pressure of the largest valve, the flow rate of 30% of normal flow. Valve requirements: anti-cavitation, anti-blocking structure, V-class seal, the pump starts and stops running the valve continuous work, Closed, the valve is usually open fault 3, the height of the heater trap (water heater hydrophobic, condensate water heater hydrophobic) control requirements: control the position of the condensate heater, timely discharge of condensate, high water discharge, normal Drainage water conditions: the saturated water, the control valve between the heater pressure is generally 6-30 kg, the last level of the trap directly connected to the condenser or deaerator. Valve requirements: Anti-flash wash, V or VI level seal, the valve is usually open fault. 4, deaerator water level control valve control requirements: to provide flow to maintain the normal deaerator water level, by adding steam to increase the water temperature to eliminate dissolved in water gas conditions. Conditions: Start-up phase flow Small, large pressure differential, normal flow, pressure is small, the condition is similar to the water valve. Valve requirements: lower flow effective anti-gas . 5, the temperature control valve (desuperheater) control requirements: the high-pressure water injection into the steam to achieve the steam temperature control requirements conditions conditions: water, large pressure valve requirements: the type of diversity: Nozzle-assisted atomization Type, self-contained and folder type. 6, temperature reducing valve (high and low pressure bypass valve) control requirements: the high temperature and high pressure steam to a certain temperature and pressure of steam to the steam turbine to provide a bypass channel, the boiler can Independent steam turbine and work conditions conditions: high temperature and pressure steam, the valve requirements: thermal shock, noise reduction, rapid response.