Continuous Control
Whatever the industry or application, process control actuators are selected for precision and accuracy. They operate control valves to provide a level of consistency and reliability that only automation can provide.
控制阀是过程控制的核心：通过执行器操作时，它们会因响应流量，压力或温度等变量而改变液体或气体的流动。调节控制阀通常用于过程控制系统和可变流系统，这些系统需要根据过程系统的设定点要求进行调整。
Process control actuators provide exact position control and continuous modulation and are therefore used within a wide variety of applications, including chemical production, food and beverage, mining, power stations and water sites. In oil and gas applications they can be found at wellheads, choke valves on shale gas installations and stroke adjusters on metering pumps. The high degree of precision provided by process control actuators can significantly reduce process variability, positively impacting on the quality of the product produced and the production capacity a plant can achieve.
消除过程可变性
在使用闭环系统的过程控制应用程序中，过程可变性是一种极为不良的行为。它是控制循环性能不佳的大型贡献者，并且正在稳定。在整个过程中可以施加的精度越大，可以施加的控制程度就越大。这创造了一致性。过程控制执行器在闭环控制应用中经常调整；它们必须保持一致，以确保始终达到最终目标输出。执行器提供的过程一致性重要性的一个例子是工业燃烧（例如，在玻璃制造中）。在这里，关键要求是操作效率和消除过程可变性。通过传感器在控制循环中发送信号以确保该过程的执行，可以监视标准燃烧过程。过程控制执行器的一个重要特征是精确定位性能能力。 Rotork’s CVA precision modulating actuators, for example, can respond to a change in position that is almost instantaneous. Position control (using a 4 to 20 mA signal) provides up to 0.1% accuracy. For combustion, when the correct injection of fuel and air is controlled by the actuator, complete and efficient combustion is ensured. This complete combustion, producing an optimum level of heat without leaving any unburned and wasted fuel, is key to reducing emissions, saving money and meeting regulatory standards. With actuators that eliminate process variability (designed and built to be on control loop applications), process applications such as industrial combustion are truly reliable and stable. For example, CVA actuators were installed on globe valves at an Asian fibreglass manufacturerto provide accurate control of the ratio of natural gas and oxygen to melt raw glass in the furnace. The precision of the appropriate process control actuators allowed complete combustion, saving gas and oxygen.
在持续使用中
There are many industries and applications that require process control actuators, largely because of the need for continual use. Appropriate flow control solutions should offer continuous, modulating control that can withstand the high demands of operating over an extended period without sacrificing accuracy and precision. Modulating control is not a simple on/off mechanism, but precisely controls the flow rate. Within food and beverage production, repeatable position control ensures repeatability and a product that has no variability. Creating a consistent final product that is the same, day after day, is a fundamental requirement within the industry. Rotork’s CVA control valve actuators provide modulating and failsafe duties at a Coca-Cola Enterprises site in Wakefield, UK. They were chosen as part of an upgrade from existing pneumatic actuators to reduce the cost of providing and maintaining an air supply. The actuators are used in production and clean-in-place operations.
氢产生
在新兴能源系统中发现过程控制。全球能源提供必须从化石燃料中移开，以实现减少排放的国际目标。诸如氢之类的替代能源生产继续增长。绿色氢（由于可再生能量被喂养，仅在燃烧时释放水）（由于它被释放出来，因此被认为是完全不发射的），可以通过电解产生，这需要过程控制执行器才能精确控制。当前生产氢的成本相对较高意味着必须平稳，有效地运行生产。工艺控制执行器允许在电解过程中自动化水，氢和任何相关的碳氢化合物；这个精度是必不可少的。此类应用程序中的过程控制执行器具有爆炸性认证（例如ATEX，CSA，IECEX），以确保安全。专用过程控制解决方案对于需要连续/调节作用的应用至关重要，包括化学生产，水，食物和饮料，动力，采矿以及各种石油和天然气系统。过程控制执行器提供可重复的可靠绩效，以降低或消除过程可变性并确保一致和可靠的结果。
Reproduced with kind permission from International Process Engineer magazine.