【導讀】是鍋爐正常生產運行的主要指標之一。若水位過高,影響汽水分離的效果,使用氣設。位必須嚴加控制。為了確保鍋爐生產的穩(wěn)定、可靠和經濟運行，我們設計采用了性。該控制系統(tǒng)通過檢測水汽壓力、溫度，汽包液位等運行物理量，在運。行過程中全自動調節(jié)，保證了工業(yè)鍋爐的安全穩(wěn)定高效運行。而利用余熱氣體作。為熱交換介質的余熱鍋爐在全國占有很大的比例，其節(jié)能降耗效果尤為明顯。鍋爐是一個較為復雜的調節(jié)對象，為保證提供合格的蒸汽。鍋爐計算機控制是近年來開發(fā)的一項新技術。調節(jié)量則是給水流量，通過對給水流量的調節(jié)，使汽包內部的物料達到動態(tài)平衡，造成這一原因是由于負荷增加時，導致汽包壓力下降，使汽包內水的沸點溫。度下降，水的沸騰突然加劇，形成大量汽泡，而使水位抬高。實質上是維持鍋爐進出水量平衡的系統(tǒng)。算后調節(jié)給水閥的調節(jié)系統(tǒng)。且給水調節(jié)閥動作平穩(wěn)。產時波動應小于±5％。這組PID參數(shù)可以使閥位波動幅度不大而回路有。液位波動范圍＜±3％。

　　

【正文】 such needs to have the rapid reaction regarding the industry boiler the closed loop return route control to have to use this functional need beforehand to appraise whether feasible. Typical closed loop return route program control schematic drawing like chart 6 shows. Chart5 typical closed loops return routes program control schematic drawing According to applies the request, the user establishes the PID controller the proportion + integral + differential controller, its controller digitization mathematical expression as follows: Mn: n time control output D4005: The gain constant, tacitly approves the value is 1,000。 May establish the scope is 1 ~ 5,000 Pb: Hou ratio(scope: 1 ~ 5,000, the unit is %。 Kc (gain) =D4005/Pb) En: n the time error = supposes the definite value (SP) n the time process to change the value (PVn) Ki: Constant of integration (scope: 0 ~ 9,999, is equal to ~ Repeats/Minute) Td: Fluxionary calculus timeconstant (scope: 0 ~ 9,999, is equal to ~ ) PVn: n the time process changes the value PVn1: n the time previous process changes the value Ts:PID operation time interval (scope: 1 ~ 3,000, unit: ) Bias: Bias output (scope: 0 ~ 16,383) Adds on the micro subitem the controller, the goal lies in the elimination program control system excessively to respond that, then enables the program control system steadily to relax achieves stably. Although the micro subitem has the above merit, but because it is quite keen to the output contribution, the majority of applications do not need to use the micro subitem but the Td hypothesis are 0. Tuning PID control parameters control system design is the core content. It is according to is controlled the process the characteristic to determine the PID controller the scaleup factor, the integration time and the differential time size. Tuning PID control parameters are many ways, summarizes has two big kinds: One is the theory of the entire titration. It mainly is rests on the system the mathematical model, the process theoretical calculation definite controller parameter. This method obtained arrives the estimated data not necessarily may straight take over the use of, but also must actually carry on the adjustment and the revision through the project. The second is tuning method, it mainly relies on the project experience, directly carries on in the control system experiment, also the method simple, is easy to grasp, is actual in the project is widely used. The PID controller parameter project tuning method, mainly has the critical ratio method, the response tune longbase method and fades the subtraction. Three methods respectively have its characteristic, its mon ground all is through the experiment, then carries on according to the project empirical formula to The controller parameter setting. But regardless of uses the controller parameter which which one method obtained arrives, all needs to carry on the final adjustment and the consummation in the actual movement. Now generally uses is the critical ratio method. Carries on the PID controller parameter as follows using This method tuning the step (1) first in advance chooses an enough short sampling period to let the system work。 (2) only joins the proportional control link, appears the threshold oscillation until the system to the input step leap response, took down the by now proportion magnification factor and the threshold oscillation cycle。 (3) in certain controls under the system to obtain the PID controller through the formula putation the parameter. Except for this for guaranteed the boiler movement the security, when carries on the automation control system design, to the boiler water level, the boiler dome pressure and so on the important parameter should establish the conventional measuring appliance and the alarm device, guaranteed the water level and the dome pressure have the dual even tertiary alarm device, this is essential, in order to avoid the boiler has the significant accident. 5 concluding remark Because used PLC to carry on the control, system function perfect, structure advanced reasonable, energy consumption small, expansion nimble, was advantageous for the maintenance, and the reliability was high, moreover also enormously enhanced enterprise39。s production efficiency and the economic efficiency. This system automaticity higher, greatly reduced the operator labor intensity, reduced the cost, passed through the nearly 2 years movement, the user gives has very high appraised, thought use domestic product forever great PLC development control system function perfect, prehensive nature strong, manmachine contact surface friendly, the usability was good. Along with the domestically produced outstanding programmable controller and the high speed decision element fast development, the boiler control system will be able to be more perfect.