外文翻译---PLC在蒸汽锅炉汽包液位PID控制系统的应用分析.docx

附录2：外文翻译PLC in steam boiler steam drum fluid position PID control system applied analysis 1 introductionThe industry steam boiler steam drum water monitor duty is the control causes it for the water current capacity with the transpiration rate maintenance dynamical equilibrium, maintains the steam drum water level in the craft permission scope, is guarantees the boiler safety in production movement the essential condition, also is one of boiler regular production movement major targets or quotas. If the water level excessively is high, affects the soft drink separation the effect, the use was mad the equipment breaks down; But the water level excessively low can destroy the soft drink circulation, is serious when causes the explosion of a boiler, therefore the boiler steam drum water level must strictly control. In order to guarantee the boiler to produce stable, reliable and the economical movement, we designed use the performance to be advanced the boiler PID automatic control system which forever great automatic equipment and so on FBs-PLC, frequency conversion velometer, computer application will compose. This control system through examination water vapor pressure, temperature, movement physical quantity and so on steam drum fluid position, in movement process entire automatic control, has guaranteed the industry boiler security stable highly effective movement.2 industries boilers related craft introductionThe steam boiler is the factories and mines important power equipment, its duty is the supplies qualified stable steam, satisfies the load the need. Therefore, boiler production process each main parameter all must strictly control. But holds the very great proportion using the afterheat gas as the heat change medium afterheat boiler in the nation, its energy conservation falls consumes the effect especially to be obvious. Some chemical plant sulfuric acid afterheat boiler is the furnace gas which comes out using the ebullition stove (mainly is SO2) the hyperpyrexia, takes it as the heat change object, through afterheat boiler vice- mid-production pressure steam for each production branch factory use, also has guaranteed the production need, also had achieved the energy conservation falls the goal which consumes. The boiler is a more complex controlled member, provides the qualified steam for the guarantee to meet the load need, if the necessary design control system must satisfy each main craft parameter the need. Afterheat boiler technical process like chart 1 shows:3 controls difficulties analysisThe boiler computer control is a new technology which the recent years developed. It is the microcomputer soft, the hardware, the automatic control, the boiler energy conservation and so on several technical in close integration with product, as the boiler control device, its primary mission is guaranteed the boiler the security, is stable, the economical movement, reduces operators labor intensity. Uses the micro computer control, can carry on the process to the boiler the automatic detection, the automatic control and so on many functions. It is adjusted the quantity is the steam drum water level, but adjusts the quantity is for the water current capacity, through to gives the water current capacity the adjustment, enables the steam drum interior the material to achieve the dynamical equilibrium, changes in the permission scope, although the boiler steam drum water level assumes the positive characteristic to the vapor current capacity and for the fluent quantity change response, but when load (vapor current capacity) sharp growth, performance actually similar counter response characteristic, namely so-called false water level. Creates this reason is because time load increase, causes the dome pressure to drop, causes the steam drum 内水 boiling temperature to drop, the water ebullition suddenly intensifies, forms the massive steam bubbles, but makes the water level to raise. The steam drum water monitor system, in the essence is maintains the boiler turnover water volume balance the system. It is by the water level took the water volume balance or not control target, through adjusts the water volume how many to achieve the turnover balance, maintains the steam drum water level in the soft drink separation contact surface biggest steam drum nearby the position line, enhances the boiler the vaporization efficiency, 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 so-called 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.First and obtains respective signal through vapor stream quantitative change delivering for fluent quantitative change delivering while by the corresponding scale-up factor, may adjust the steam current capacity through the scale-up 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 DDk-WWk+H-G=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 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 pre-heater 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 operators operation, thinks the reduction thus to stabilize to the water volume undulation to the water temperature becomes 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.中文原文PLC在蒸汽锅炉汽包液位PID控制系统的应用分析1 引言 工业蒸汽锅炉汽包水位控制的任务是控制给水流量使其与蒸发量保持动态平衡，维持汽包水位在工艺允许的范围内，是保证锅炉安全生产运行的必要条件，也是锅炉正常生产运行的主要指标之一。若水位过高,影响汽水分离的效果,使用气设备发生故障;而水位过低则会破坏汽水循环,严重时导致锅炉爆炸，所以锅炉汽包水位必须严加控制。为了确保锅炉生产的稳定、可靠和经济运行，我们设计采用了性能先进的永宏FBs-PLC、变频调速器、计算机应用等自动化设备组成的锅炉PID自动控制系统。该控制系统通过检测水汽压力、温度，汽包液位等运行物理量，在运行过程中全自动调节，保证了工业锅炉的安全稳定高效运行。2 工业锅炉相关工艺介绍 蒸汽锅炉是厂矿重要的动力设备，其任务是供给合格稳定的蒸汽，以满足负荷的需要。为此，锅炉生产过程的各个主要参数都必须严格控制。而利用余热气体作为热交换介质的余热锅炉在全国占有很大的比例，其节能降耗效果尤为明显。某化工厂硫酸余热锅炉就是利用沸腾炉出来的炉气(主要是SO2)温度过高，将其作为热交换对象，通过余热锅炉副产中压蒸汽供各生产分厂使用，既保证了生产需要，也达到了节能降耗的目的。锅炉是一个较为复杂的调节对象，为保证提供合格的蒸汽以适应负荷的需要，与其配套设计的控制系统必须满足各主要工艺参数的需要。余热锅炉工艺流程如图1所示。 3 控制难点分析 锅炉计算机控制是近年来开发的一项新技术。它是微型计算机软、硬件、自动控制、锅炉节能等几项技术紧密结合的产物，作为锅炉控制装置，其主要任务是保证锅炉的安全、稳定、经济运行，减轻操作人员的劳动强度。采用微计算机控制，能对锅炉进行过程的自动检测、自动控制等多项功能。它的被调量是汽包水位，而调节量则是给水流量，通过对给水流量的调节，使汽包内部的物料达到动态平衡，变化在允许范围之内，虽然锅炉汽包水位对蒸气流量和给水流量变化的响应呈积极特性，但是在负荷(蒸气流量)急剧增加时，表现却类似逆响应特性，即所谓的虚假水位。造成这一原因是由于负荷增加时，导致汽包压力下降，使汽包内水的沸点温度下降，水的沸腾突然加剧，形成大量汽泡，而使水位抬高。