电力行业控制阀的类型与正确选用

译文：
电力是最重要的能源行业之一，目前有蒸汽、风力、水力、地热、潮汐发电、太阳能发电，本文重点讨论燃油、煤油、燃气及核电站中部分典型控制阀的选用。这类电站共同点就是将水汽化为蒸汽，利用蒸汽驱动气轮机带动发电机产生电力，不同点是将水转化成蒸汽的能源各不相同，分别有：天然气、燃油、煤炭、原子堆。各种电站的结构大致相同，我们先以联合循环电站为例来简述控制阀的选用，然后再将各电站中不同的部分作简要说明。 简单来看电力流程图实际上是水、蒸汽的循环流程，在此流程中选用控制阀既简单又复杂。简单的是过程介质简单，只有水和蒸汽两种，复杂的是水和蒸汽的温度与压力波动范围大，带来系列问题如：闪蒸、气蚀、冲刷、噪音、腐蚀。但首先要考虑的是控制阀的安全性与可靠性。 我们按照系统流程来展开控制阀选用说明。 1、给水阀主、副锅炉给水阀、复合型给水调节阀 控制要求：控制锅炉进水，维持汽锅液位与蒸汽流量。 工况要求：锅炉启动时阀门压差可达100-300公斤，流量较小，正常运行时压差较小，流量大，流量可调比为75:1-100:1。 阀门要求：阀体材质为WCB/WC9，对于双阀系统中的启动阀要求抗气蚀，V级关闭等级，对于复合型给水阀需使用特性化阀内件同时满足锅炉启动与正常运行时的需要。一般阀门选择为故障关，(需要注意的是一般给水中为消除溶解其中的氧会加入联胺进行处理，它会对SATELLITE6号合金或其它的类似合金产生不良反应，所以最好不使用316+STELLITE堆焊的方法处理阀内件，可直接选用416不锈钢材料)。 2、锅炉给水泵最小流量循环阀 控制要求：使锅炉给水泵安全启动及运行，消除因流量过小、温升增加、水强烈气蚀使泵损坏。(老式电站有使用开关型的最小流量控制阀，同时还有使用机械式的泵自动循环阀)。 工况情况：压降达160-350公斤，是电站系统中承受压差最大的阀门，流量一般为正常流量的30%。 阀门要求：抗气蚀，防堵结构，V级密封等级，泵启动与停止运行时阀门连续工作，泵正常启动后次阀门关阀，阀门通常为故障开。 3、高/低加热器疏水阀给水加热器疏水、冷凝水加热器疏水 控制要求：控制加热器中冷凝水的位置，及时将冷凝水排放，即高水位排放，正常水位疏水。 工况情况：介质为饱和水，加热器之间的控制阀压差一般为6-30公斤，最后一级疏水阀直接连接冷凝器或除氧器。 阀门要求：抗闪蒸冲刷，V或VI级密封等级，阀门通常为故障开。 4、除氧器水位控制阀(DALC) 控制要求：提供流量保持除氧器正常水位，通过加入蒸汽提高水温消除溶解在水中的气体。 工况情况：启动阶段流量较小，压差较大，正常情况流量大，压差小，工况类似给水阀。 阀门要求：较低流量时有效抗气蚀， 5、减温阀(减温器) 控制要求：将高压水喷射入蒸汽中使蒸汽温度达到控制要求。 工况情况：介质为水，压差较大，阀门要求：类型多样：喷嘴型，辅助雾化型，自我包容型及对夹型。 6、减温减压阀(高、低压旁路阀) 控制要求：将高温高压蒸汽调整到一定温度压力的蒸汽；给汽机提供一个旁路通道，锅炉能够独立汽机而工作。 工况情况：高温高压蒸汽减温减压。 阀门要求：抗热冲击，降噪，反应迅速。

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原文：
Electricity is one of the most important energy sector, there are steam, wind, hydro, geothermal, tidal power, solar power, this paper focuses on fuel, kerosene, gas and nuclear power plants in the selection of some typical control valve. Common in those plants is to water vapor into steam, using steam-driven gas turbine driven generators to produce electricity, is the difference between the energy of water into steam vary are: natural gas, fuel oil, coal, atomic heap. The structure of the various power plant similar to our first example of combined cycle power plant control valves used briefly, and then different parts of the station for a RVEX electric resilient seated gate valves brief description. Power flow chart is actually a simple view of water, steam cycle process used in this process both simple and complex control valves. Simple is the process medium is simple, only water and steam are two kinds of complex water and steam temperature and pressure fluctuation range, bringing a series of issues such as: flash, cavitation, erosion, noise, corrosion. But the first thing to consider is the control valve of the safety and reliability. We follow the system flow control valve to begin instruction. 1, water Fa Zhu, vice boiler valve, water valve complex Control requirements: control boiler water, the maintenance of boilers and steam flow level. Condition requirements: boiler starts up to 100-300 kg of pressure valves, low flow, low pressure drop during normal operation, traffic flow, flow adjustable ratio 75:1-100:1. Valve requirements: Body material to WCB/WC9, for the two-valve system requirements start anti-cavitation valve, V-class closing level, the need to use Fuge type characterization to the valve trim meet boiler startup and normal operation needs. Generally choose to fault off valve, (Note that the general to the water to remove dissolved RRHX rising stem resilient seated gate valves oxygen which will be handled by adding hydrazine, which would SATELLITE6 No. alloy or other alloys of similar adverse reactions, so it is best not to use 316 + STELLITE surfacing approach to trim that is, using 416 stainless steel). 2, boiler feed pump minimum flow valve cycle Control requirements: safety of boiler feed pump start and run, to eliminate traffic flow is too small, temperature increase, water strong cavitation damage to pumps. (The old power station with the minimum use of switch-based flow control valve, as well as using a mechanical pump automatic cycling valve). Conditions: The pressure drop up to 160-350 kilograms, is the largest power plant systems to withstand pressure valves, flow generally normal flow of 30%. Valve requirements: resistance to cavitation, attempts to prevent the structure, V-class seal level, the pump start and stop running when the valve continuously, the pump normally starts off valve after the second valve, the valve is usually opened for the failure. 3, High / Low Water Heater Heater Traps, Condensate Heater Control requirements: Control the location of condensed water heater, condensate discharge in time, that high water discharge, the normal water level of hydrophobicity. Conditions: The medium is saturated water heater control valve between the pressure is generally 6-30 kg, and finally a trap directly connected to the condenser or deaerator. Valve requirements: flash erosion resistance, V or VI level seal level, the valve is usually opened for the failure. 4 deaerator water level control valve (DALC) Control requirements: to provide flow to maintain the normal water level of deaerator, by adding steam to increase temperature to eliminate the gas dissolved in water. Condition: The flow of small start-up phase, a greater pressure, the normal flow rate, pressure difference, similar to the valve condition. Valve requirements: Special fire signal res-ilient seated gate valves low flow cavitation effect at the time, 5, reducing temperature valve (desuperheater) Control requirements: the high-pressure water jet of steam into the steam temperature of manipulation to control demand. Conditions: The medium is water, a larger pressure difference, valve requirements: type diversity: nozzle type, assisted atomization type, self-contained type, and on the clip. 6 Reduction Valve (high and low pressure bypass valve) Control requirements: the high temperature high pressure steam to adjust to a certain temperature and pressure of steam; to provide a bypass channel turbine, boiler and steam turbine capable of independent work. Condition: The high temperature high pressure steam temperature and pressure reduction. Valve requirements: thermal shock, noise reduction, quick response.