原文：
　 1 调节阀的组成与分类 调节阀又称控制阀，是执行器的主要类型，通过接受调节控制单元输出的控制信号，借助动力操作去改变流体流量。调节阀一般由执行机构和阀门组成。如果按其所配执行机构使用的动力，调节阀可以分为气动、电动、液动三种，即以压缩空气为动力源的气动调节阀，以电为动力源的电动调节阀，以液体介质(如油等)压力为动力的电液动调节阀，另外，按其功能和特性分，还有电磁阀、电子式、智能式、现场总线型调节阀等。调节阀的产品类型很多，结构也多种多样，而且还在不断更新和变化。一般来说阀是通用的，既可以与气动执行机构匹配，也可以与电动执行机构或其他执行机构匹配。 2 调节阀类型的选择 2.1 调节阀的阀体类型选择阀体的选择是调节阀选择中最重要的环节。 调节阀阀体种类很多，常用的有直通单座、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10种。在选择阀门之前，要对控制过程的介质、工艺条件和参数进行细心的分析，收集足够的数据，了解系统对调节阀的要求，根据所收集的数据来确定所要使用的阀门类型。在具体选择时，可从以下几方面考虑: (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，阀芯、阀座接合面每一次关闭都会受到严重摩擦。因此阀门的流路要光滑，阀的内部材料要坚硬。 (3)耐腐蚀由于介质具有腐蚀性，在能满足调节功能的情况下，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，闪蒸和空化不仅影响流量系数的计算，还会形成振动和噪声，使阀门的使用寿命变短，因此在选择阀门时应防止阀门产生闪蒸和空化。 2.2 调节阀执行机构的选择 2.2.1 输出力的考虑 执行机构不论是何种类型，其输出力都是用于克服负荷的有效力(主要是指不平衡力和不平衡力矩加上摩擦力、密封力、重力等有关力的作用)。因此，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克服各种阻力，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{zd0}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。 2.2.2 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，且接线盒为防爆型，不能选择电动执行机构。如果没有防爆要求，则气动、电动执行机构都可选用，但从节能方面考虑，应尽量选用电动执行机构。对于液动执行机构，其使用不如气动、电动执行机构广泛，但具有调节精度高、动作速度快和平稳的特点，因此，在某些情况下，为了达到较好调节效果，必须选用液动执行机构，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。 3 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。 4 调节阀流，特性的选择 调节阀的流量特性是指介质流过阀门的相对流量与位移(阀门的相对开度)间的关系，理想流量特性主要有直线、等百分比(对数)、抛物线和快开等4种，特性曲线和阀芯形状如图1和图2所示。常用的理想流量特性只有直线、等百分比(对数)、快开三种。抛物线流量特性介于直线和等百分比之间，一般可用等百分比特性来代替，而快开特性主要用于二位调节及程序控制中，因此调节阀特性的选择实际上是直线和等百分比流量特性的选择。 调节阀流量特性的选择可以通过理论计算，但所用的方法和方程都很复杂。目前多采用经验准则，具体从下几方面考虑:①从调节系统的调节质量分析并选择;②从工艺配管情况考虑;③从负荷变化情况分析。 选择好调节阀的流量特性，就可以根据其流量特性确定阀门阀芯的形状和结构，但对于像隔膜阀、蝶阀等，由于它们的结构特点，不可能用改变阀芯的曲面形状来达到所需要的流量特性，这时，可通过改变所配阀门定位器的反馈凸轮外形来实现。 5 调节阀口径的选择 调节阀口径的选择和确定主要依据阀的流通能力即Cv。在各种工程的仪表设计和选型时，都要对调节阀进行Cv计算，并提供调节阀设计说明书。从调节阀的Cv计算到阀的口径确定，一般需经以下步骤: 1)计算流量的确定。现有的生产能力、设备负荷及介质的状况，决定计算流量的Qmax和Qmin. 2)阀前后压差的确定。根据已选择的阀流量特性及系统特点选定S(阻力系数)，再确定计算压差。 3)计算Cv。根据所调节的介质选择合适的计算公式和图表，求得Cmax和Cmin. 4)选用Cv。根据Cmax,在所选择的产品标准系列中选取>Cmax且与其最接近的一级C. 5)调节阀开度验算。一般要求{zd0}计算流量时的开度≯90%，最小计算流量时的开度≮10%。 6)调节阀实际可调比的验算。一般要求实际可调比≮10。 7)阀座直径和公称直径的确定。验证合适后，根据C确定。 6 结束语 调节阀的选择是非常细致的工作，不仅要有扎实的专业理论知识，还要有丰富实践经验。选择得好不仅有利于调节控制回路PID参数的整定，使被调参数得到较好地控制效果，也使调节阀的使用寿命大大增长。调节阀的选择要因地制宜，并非一成不变，要在实践的过程中不断总结和创新，特别随着机电一体化技术、计算机和数字信息技术的应用，调节阀的结构功能变得更好、更全面，为选择调节阀提供了极大的方便。

“ Process control valve classification and selection of the composition ”是由提供的国际阀门新闻，译文仅供参考。另外，中国调节阀网还提供相关产品搜索： 、 、 、 、 等。

译文：
A control valve of the composition and classification Control valve control valve is also called, is the implementation of the main types of regulation and control unit by accepting control signal from engine operation to change the fluid flow. Valve actuator and valve are generally composed. If by their ticket enforcement agencies use the power, control valve can be divided into pneumatic, electric, hydraulic and three, that is the source of compressed air-driven pneumatic valve to call for the power source of electric control valve, the liquid medium (such as oil) pressure-powered electric hydraulic control valve, and their functions and features points, as well as solenoid valves, electronic, intelligent, fieldbus-based control valve. Many types of valve products, the structure also varied, but also constantly updates and changes. Generally speaking valve is universal, not only match with pneumatic actuator, electric actuator can be with other implementing agencies match. Choice of the type 2 control valve 2.1 Control Valve Body type selection valve control valve selection is the most important part of choice. Valve of many types, commonly used by direct single-seat, through engine, angle, diaphragm, small traffic, links, eccentric rotation, butterfly, sleeve type, spherical and other 10 species. In the choice of the valve prior to the media on the control process, process conditions and parameters of careful analysis, to collect sufficient data to understand the system requirements on the control valve, according to the data collected to determine the type of valve to be used. In the specific choices available from the following aspects: (1) disc structure, mainly based on the selected shape of the flow characteristics and considerations such as power imbalances. (2) wear resistance when the fluid medium is the high concentration of abrasive particles in suspension, the spool, the valve seat joints will be closed every time a serious friction. Therefore, the valve flow path to smooth, hard materials to the internal valve. (3) corrosion resistance as a corrosive medium, to meet regulatory function in the case, as we choose simple valve. (4) medium temperature and pressure when the medium temperature, high pressure and great change, and should be chosen disc and seat materials by temperature and pressure changes small valves. (5) to prevent the flash and the flash cavitation and cavitation only in a liquid medium. In the actual production process, the flash and the air of not only affect the calculation of flow coefficient, but also the formation of vibration and noise, shortening the life of the valve, the valve should be to prevent the valve in the choice of steam and air of . 2.2 The choice of control valve actuator 2.2.1 Output power considerations Implementing agencies of whatever type, the output power are used to overcome the load of effectiveness (mainly refers to the unbalanced force and unbalanced moment with friction, sealing force, gravity, and the role of the force). Therefore, in order to work properly regulating valve is equipped with the implementing agencies to be able to generate sufficient output power to overcome all obstacles, to ensure a high degree of sealing and the valve opening. For double acting pneumatic, hydraulic, electric actuator, generally not reset spring. Force size has nothing to do with its running direction, so the key lies in selecting executing agencies to ascertain the maximum output power and torque of the motor rotation. For single action pneumatic actuator, output force and the valve opening, control valve on the emergence of power will also affect the motion characteristics, thus requiring the entire range of control valve opening to establish equilibrium. 2.2.2 Determination of the implementation of the sector The implementation of the output power is confirmed, according to the technical use of environmental requirements, select the appropriate enforcement agency. For the scene, where explosion-proof requirements, should use pneumatic actuator, and the terminal box explosion proof, can not choose the electric actuator. If no explosion-proof requirements, pneumatic, electric actuators can be used, but energy considerations, should try to use electric actuator. For the hydraulic actuator, its use as pneumatic, electric actuators widely, but with adjustment of high precision, movement speed and stationary, therefore, in some cases, in order to achieve better regulation, it is necessary the implementation of selected hydraulic institutions, such as power plants and transparent machine speed regulation, the refinery catalytic cracking unit reactor control temperature regulation. 3 mode of action of control valve selection Mode of action of control valve pneumatic actuator only when the only choice, the role of positive and negative role adopted by the implementing agencies and valve combination of positive and negative role in the formation. There are four kinds of combination that is positive (gas off type), positive and negative (gas open type), anyway (gas open type), counter-countermeasure (gas off type), formed through the combination of these four modes of action have gas control valve two open gas off. Mode of action for the choice of control valve, the main three aspects to consider: a) process of production safety; b) characteristics of the medium; c) to ensure product quality, minimize economic losses. 4 valve flow characteristics of selected Valve flow characteristics is the medium flow through the valve flow and the relative displacement (relative valve opening) the relationship between the ideal flow characteristics are mainly linear, equal percentage (log), parabola, and 4 kinds of quick , characteristic curves, and disc shape as shown in Figure 1 and Figure 2. Ideal flow characteristics commonly used only linear, equal percentage (log), quick opening of three. Between linear and parabolic flow characteristic such as percentage, and the average percentage of features available such as to replace, but the main characteristics of quick-conditioning and process control for two, so the choice of control valve characteristics are linear and equal percentage actually flow characteristics choice. The choice of control valve flow characteristics can be calculated, but the methods and equations used are very complex. Experience criteria currently used, the specific consideration from the following aspects: ① from the conditioning analysis of the regulation of quality and choice; ② be considered from the process piping; ③ from the change of load. Select a good control valve flow characteristics, flow characteristics can be identified according to their shape and structure of the valve spool, but like the diaphragm, butterfly, etc., because of their structural features, not possible to change the surface shape of the spool to achieve the required flow characteristics, then, can change the valve positioner with feedback cam profile to achieve. 5, the choice of valve diameter Valve bore the main basis for the selection and determine the valve's flow capacity is Cv. Instrument in a variety of engineering design and selection, we need to calculate Cv regulating valve and control valve designed to provide instructions. Cv calculated from the control valve to the valve diameter is fixed, subject to the following steps: 1) Calculate the flow rate determination. Existing production capacity, equipment and medium load conditions, decided to calculate flow Qmax and Qmin. 2) determine the pressure difference before and after the valve. According to the selected valve flow characteristics and system characteristics of the selected S (drag coefficient), and then determine the calculation of pressure. 3) The calculation of Cv. According to the regulation of the media choose the right formula and charts, obtained Cmax and Cmin. 4) use Cv. According to Cmax, in the standard series of products chosen select> Cmax and the closest one with C. 5) regulating valve opening checking. General requirements for calculating the maximum flow of the opening ≯ 90%, the minimum calculated flow of the opening ≮ 10%. 6) control valve with adjustable ratio of the actual checking. General requirements than can actually be adjusted ≮ 10. 7) The seat diameter and the determination of nominal diameter. Verify appropriate, based on the C determined. 6 Conclusion Valve selection is very meticulous work, not only a solid professional theoretical knowledge, but also have rich practical experience. Is well chosen not only helps to balance control loop PID parameter tuning, so to be tone get better control effect parameters, but also to significantly increase the service life of valve. Regulating valve should be selected according to local conditions, not static, in practice, constantly sum up the process and innovation, especially with the integrated technology, computers and digital information technology, structure and function of control valve to become better, more comprehensive, To select the control valve provides a great convenience.