蒸汽调节阀

蒸汽调节阀就是以压缩空气为动力源，以气缸为执行器，并借助于电气阀门定位器、转换器、电磁阀、保位阀等附件去驱动阀门，实现开关量或比例式调节，接收工业自动化控制系统的控制信号来完成调节管道介质的流量、压力、温度等各种工艺参数。德国汉克(HANK)蒸汽调节阀的特点就是控制简单，反应快速，且本质安全，不需另外再采取防爆措施。

选型原则

调节阀的阀体类型选择

调节阀的阀体种类很多，常用的阀体种类有直通单座、直通双座、角形、隔膜、小流量、三通、偏心旋转、蝶形、套筒式、球形等。在具体选择时，可做如下考虑：

1、阀芯形状结构主要根据所选择的流量特性和不平衡力等因素考虑。

2、耐磨损性当流体介质是含有高浓度磨损性颗粒的悬浮液时，阀的内部材料要坚硬。

3、耐腐蚀性由于介质具有腐蚀性，尽量选择结构简单阀门。

4、介质的温度、压力当介质的温度、压力高且变化大时，应选用阀芯和阀座的材料受温度、压力变化小的阀门。

5、防止闪蒸和空化闪蒸和空化只产生在液体介质。在实际生产过程中，闪蒸和空化会形成振动和噪声，缩短阀门的使用寿命，因此在选择阀门时应防止阀门产生闪蒸和空化。

调节阀执行机构的选择

1、为了使调节阀正常工作，配用的执行机构要能产生足够的输出力来保证高度密封和阀门的开启。对于双作用的气动、液动、电动执行机构，一般都没有复位弹簧。作用力的大小与它的运行方向无关，因此，选择执行机构的关键在于弄清最大的输出力和电机的转动力矩。

对于单作用的气动执行机构，输出力与阀门的开度有关，调节阀上的出现的力也将影响运动特性，因此要求在整个调节阀的开度范围建立力平衡。

2、执行机构类型的确定对执行机构输出力确定后，根据工艺使用环境要求，选择相应的执行机构。对于现场有防爆要求时，应选用气动执行机构。从节能方面考虑，应尽量选用电动执行机构。若调节精度高，可选择液动执行机构。如发电厂透明机的速度调节、炼油厂的催化装置反应器的温度调节控制等。

调节阀的作用方式选择

调节阀的作用方式只是在选用气动执行机构时才有，其作用方式通过执行机构正反作用和阀门的正反作用组合形成。组合形式有4种即正正(气关型)、正反(气开型)、反正(气开型)、反反(气关型)，通过这四种组合形成的调节阀作用方式有气开和气关两种。

对于调节阀作用方式的选择，主要从三方面考虑a)工艺生产安全b)介质的特性c)保证产品质量，经济损失最小。

Steam control valve is to compressed air as the power source to the cylinder as the actuator, and by means of electrical valve positioner, converter, solenoid valve, security valve and other accessories to drive the valve, to achieve the amount of switch or proportional adjustment, Automatic control system control signal to complete the regulation of pipeline medium flow, pressure, temperature and other process parameters. Germany Hank (HANK) steam control valve is characterized by simple control, rapid response, and intrinsically safe, no need to take another explosion-proof measures.

Selection principle

The valve type of the control valve is selected

Valve valve body types are many, commonly used valve body has a single seat, through the two-seat, angle, diaphragm, small flow, three links, eccentric rotation, butterfly, sleeve, spherical and so on. In the specific choice, do the following considerations:

1, spool shape structure is mainly based on the selected flow characteristics and imbalance force and other factors to consider.

2, wear resistance When the fluid medium is a high concentration of abrasive particles containing the suspension, the valve internal material to be hard.

3, corrosion resistance As the media is corrosive, try to choose a simple structure of the valve.

4, the temperature of the medium, the pressure when the medium temperature, high pressure and change the big, should be used spool and seat material by the temperature, pressure changes small valve.

5, to prevent flash and cavitation flash and cavitation only produce in the liquid medium. In the actual production process, flash and cavitation will form vibration and noise, shorten the life of the valve, so the choice of the valve should prevent the valve flash and cavitation.

Control valve actuator selection

1, in order to make the normal operation of the control valve, with the implementation of the actuator to produce enough output to ensure a high degree of sealing and valve opening. For the double acting pneumatic, hydraulic, electric actuators, generally do not have a return spring. The magnitude of the force is independent of its direction of operation, so the key to selecting the actuator is to figure out the maximum output force and the torque of the motor.

For a single acting pneumatic actuator, the output force is related to the opening of the valve, and the force on the control valve will also affect the movement characteristics. Therefore, it is required to establish a force balance in the opening range of the entire control valve.

2, the implementation of the type of implementation of the actuator to determine the output, according to the use of environmental requirements, select the appropriate implementing agencies. For the explosion requirements at the scene, should use pneumatic actuators. From the energy-saving point of view, should try to use electric actuators. If the adjustment of high precision, you can choose the hydraulic actuator. Such as the speed adjustment of the power plant transparent machine, the temperature control control of the reactor of the refinery.

The choice of the way the valve action

The action of the control valve is only in the selection of pneumatic actuators only when the role of the way through the positive and negative role of the actuator and the combination of positive and negative valve formed. There are four kinds of combinations in the form of positive (gas type), positive and negative (gas open type), anyway (air open type), anti-anti (gas off type), through the formation of these four combinations of valve action Open and air off two.