進口調(diào)節(jié)閥的選型分析
進口調(diào)節(jié)閥的閥體類型選擇調(diào)節(jié)閥的閥體種類很多，常用的閥體種類有直通單座（進口氣動單座調(diào)節(jié)閥、進口電動單座調(diào)節(jié)閥）、直通雙座（進口氣動雙座調(diào)節(jié)閥、進口電動雙座調(diào)節(jié)閥）、角形（進口角型調(diào)節(jié)閥）、隔膜（進口氣動隔膜調(diào)節(jié)閥）、小流量（進口小流量調(diào)節(jié)閥、進口小口徑調(diào)節(jié)閥）、三通（進口三通合流調(diào)節(jié)閥、進口三通分流調(diào)節(jié)閥）、偏心旋轉、蝶形（進口調(diào)節(jié)型蝶閥）、套筒式、球形（進口調(diào)節(jié)型球閥、進口V型切斷球閥）等。在具體選擇時，可做如下考慮：
(1) 閥芯形狀結構主要根據(jù)所選擇的流量特性和不平衡力等因素考慮。
(2) 耐磨損性當流體介質(zhì)是含有高濃度磨損性顆粒的懸浮液時，閥的內(nèi)部材料要堅硬。
(3) 耐腐蝕性由于介質(zhì)具有腐蝕性，盡量選擇結構簡單閥門。
(4) 介質(zhì)的溫度、壓力當介質(zhì)的溫度、壓力高且變化大時，應選用閥芯和閥座的材料受溫度、壓力變化小的閥門。
(5) 防止閃蒸和空化閃蒸和空化只產(chǎn)生在液體介質(zhì)。在實際生產(chǎn)過程中，閃蒸和空化會形成振動和噪聲，縮短閥門的使用壽命，因此在選擇閥門時應防止閥門產(chǎn)生閃蒸和空化。調(diào)節(jié)閥執(zhí)行機構的選擇為了使調(diào)節(jié)閥正常工作，配用的執(zhí)行機構要能產(chǎn)生足夠的輸出力來保證高度密封和閥門的開啟。對于雙作用的氣動、液動、電動執(zhí)行機構，一般都沒有復位彈簧。作用力的大小與它的運行方向無關，因此，選擇執(zhí)行機構的關鍵在于弄清最大的輸出力和電機的轉動力矩。對于單作用的氣動執(zhí)行機構，輸出力與閥門的開度有關，調(diào)節(jié)閥上的出現(xiàn)的力也將影響運動特性，因此要求在整個調(diào)節(jié)閥的開度范圍建立力平衡。執(zhí)行機構類型的確定對執(zhí)行機構輸出力確定后，根據(jù)工藝使用環(huán)境要求，選擇相應的執(zhí)行機構。對于現(xiàn)場有防爆要求時，應選用氣動執(zhí)行機構。從節(jié)能方面考慮，應盡量選用電動執(zhí)行機構。若調(diào)節(jié)精度高，可選擇液動執(zhí)行機構。如發(fā)電廠透明機的速度調(diào)節(jié)、煉油廠的催化裝置反應器的溫度調(diào)節(jié)控制等。調(diào)節(jié)閥的作用方式選擇調(diào)節(jié)閥的作用方式只是在選用氣動執(zhí)行機構時才有，其作用方式通過執(zhí)行機構正反作用和閥門的正反作用組合形成。組合形式有4種即正正(氣關型)、正反(氣開型)、反正(氣開型)、反反(氣關型)，通過這四種組合形成的調(diào)節(jié)閥作用方式有氣開和氣關兩種。對于調(diào)節(jié)閥作用方式的選擇，主要從三方面考慮a)工藝生產(chǎn)安全b)介質(zhì)的特性c)保證產(chǎn)品質(zhì)量，經(jīng)濟損失最小。
Control valve control valve valve valve type selection many different types of body types have commonly through single-seat, through two-seater, angular, diaphragm, low flow, tees, eccentric rotation, butterfly, sleeve type, ball and so on. In the specific choice, do the following considerations (1) spool shape and structure mainly based on the selected flow characteristics and unbalanced forces and other factors considered. (2) wear resistance when the fluid medium that contain high concentrations of wear particles in suspension, the valve's internal materials to be hard. (3) corrosion resistance as corrosive media, try to choose simple valve. (4), medium temperature and pressure when the medium temperature, high pressure and the variation shall be selected by the valve and seat materials, temperature, small changes in pressure valve. (5) to prevent steam and air steam and air produced only in a liquid medium. In the actual production process, steam and air to form the vibration and noise, shorten the life of the valve, so the choice should be to prevent the valves have valve steam and air. Valve actuator control valve to make the choice to work with the implementing agency to be able to use to generate sufficient output power to ensure a high degree of sealing and the valve open. For double-acting pneumatic, hydraulic, electric actuator, generally not reset spring. The size of the force and the direction it has nothing to do, therefore, lies in selecting executing agencies to ascertain the maximum output power and torque of the motor rotation. For single-acting pneumatic actuator, the output power and opening the valve, control valve on the emergence of the force will also affect the motion characteristics, thus requiring the entire range of valve opening to establish equilibrium. Determine the type of actuator output force of the implementing agencies to determine, based on the use of environmental technology requirements, select the appropriate enforcement agency. For the scene, explosion-proof requirements, should use pneumatic actuators. From energy considerations, should try to use electric actuators. If the adjustment of high precision, optional hydraulic actuators. Such as power plants and transparent machine speed regulation, refinery catalytic cracking unit reactor temperature adjustment control. Mode of action of control valve control valve selection in the selection of the mode of action is only when the pneumatic actuator, and its mode of action through the implementing agencies and the positive and negative effects of positive and negative role of the combination of valve formation. There are four combinations that are positive (gas-off), positive and negative (gas open type), anyway (gas open type), counter-countermeasure (gas-off), formed by a combination of these four modes of action with the gas control valve open gas off two. Mode of action for the choice of control valve, the main three aspects to consider a) process to produce safe b) characteristics of the medium c) to ensure product quality, minimize economic losses.
