锅炉自动给水外文翻译--plc在蒸汽锅炉汽包液位pid控制系统的应用分析-plc设计(编辑修改稿)

锅炉自动给水外文翻译--plc在蒸汽锅炉汽包液位pid控制系统的应用分析-plc设计(编辑修改稿)内容摘要：

ency, the guarantee production safety. Because the boiler water level system is equipped with the balance of the ability to control the object, in the movement has the false water level phenomenon, in the practical application may use the water level single impulse, the water level steam quantity double impulse and the water level, the steam quantity according to the situation, gives the water volume three impulses the control systems. The socalled three impulses governing system is gives water current capacity W, steam drum water level H, the steam current capacity D three variables adjusts after the operation gives the water valve the governing system. Concrete adjustment process block diagram like chart 2 shows Chart 2 impulse adjustment block diagram First and obtains respective signal through vapor stream quantitative change delivering for fluent quantitative change delivering while by the corresponding scaleup factor, may adjust the steam current capacity through the scaleup factor or give the water current capacity to the governing system influence dynamics. Changes delivering through the difference pressure to obtain the water level signal to take host adjustment signal H. If the water level supposes the definite value is G, then should have under the equilibrium condition DDkWWk+HG=0 relational type existence. Dk is steam discharge coefficient Wk gives the water discharge coefficient. If again establishes time, guaranteed DDk=WWk that may obtain H=G under the stable state. This time the regulator output on with conforms to the correspondence, stops to the water valve in some position. If has or many signals changes, the state of equilibrium is destroyed, the PI adjustment module output will certainly to change. When the water level elevated, then the adjustment module output signal reduces, causes to close slightly for the water regulating valve. Otherwise, when the water level reduces, the adjustment module output value increases, causes to open in a big way to the water valve. The practice proved three impulses can maintain the water level for the water single pole regulator system stably, also gives the water regulating valve movement to be steady. The boiler also has a quite important control loop for the aqueous system in is for the hydraulic pressure return route, because the steam drum internal pressure is higher, must make up the water to the boiler to have to provide a higher pressure, enhances the hydraulic pressure for the hydraulic pressure return route function, enables the water normally to pour into the steam drum. But in the steam current capacity had not achieved when full load, to gives the water current capacity the request not to be high. Generally uses the feed pump in the old style boiler system continuously by the labor frequency way revolution, reduces the hydraulic pressure with the return valve to prevent the cartridge igniter, now generally uses through the frequency changer constant pressure water supply way control hydraulic pressure. Boiler to water volume through steam drum fluid position adjustment. The steam drum fluid position survey selects floats the tube liquidometer. For the effective use transformation waste heat, reduces the consumption, decreases the labor intensity, is advantageous is stable to the overall craft, requests the steam drum fluid position automatic control, when regular production the undulation should be smaller than 177。 5%. The PID adjustment steam outlet valve may the very good control dome pressure. After drives normally undulates the scope not to be big, may not consider. The transformed load undulation, the preheater boiler for the water temperature change, the boiler load undulation, dumps pollutants the quantitative change these factors to have to consider to the steam drum fluid position influence. Take the steam drum fluid position as the main tuning parameter, take gives the water current capacity as the vice accent parameter, take the steam current capacity as a forward feed, but the adjustment effect is very bad. Causes the steam drum fluid position major rises and falls. Considered this waste heat boiler controlled variable coupling small, flow simple, produces the steam quantity to be also stabler, we are inspired from in operator39。 s operation, thinks the reduction thus to stabilize to the water volume undulation to the water temperature bees this waste heat boiler fluid position control the main point. Therefore we select to the steam decide the water + fluid position forward feed the ratio control plan, plan diagram like chart 3 shows. Chart 3 the steam decides the water + fluid position forward feed ratio control plan diagram Coefficient K is the soft drink loss factor (gives water current capacity and steam current capacity ratio), the scope is ~ . The PID parameter is P = 300%, I = , D = 0. This group of PID parameter may enable the valve position margin。