Problems in the application of pressure control valves

1. Problems existing in the application of pressure control valves

    ¢ÙThere are numerous varieties, specifications, and parameters of pressure control valves. To accommodate the control requirements of different industrial production processes, such as temperature, pressure, and medium characteristics, there are nearly a thousand different types and specifications of pressure control valves, making the selection, installation, application, maintenance, and management of these valves inconvenient.

    ¢ÚThe reliability of the pressure control valve is poor. There is a significant difference between the characteristics of the pressure control valve at the factory and those after operating for a period of time. For example, the leakage increases, noise increases, and the valve's reproducibility deteriorates, which poses difficulties for long-term stable operation.

    ¢Û The pressure control valve is bulky, which brings inconvenience to the transportation, installation, and maintenance of the control valve. Generally, the weight of a control valve is several times to hundreds of times heavier than that of a typical instrument. For example, a DN200 control valve weighs up to 700kg, and its transportation, installation, and maintenance require the use of some mechanical equipment, which brings inconvenience to the application of the control valve.

    ¢ÜThe flow characteristics of the pressure control valve do not match the characteristics of the industrial process controlled object, resulting in a deterioration in the quality of the control system. The ideal flow characteristics of the pressure control valve are determined at the time of product delivery, but the characteristics of the industrial process controlled object vary, and the pressure drop ratio changes, making it impossible for the operating flow characteristics of the control valve to match the characteristics of the controlled object, and deteriorating the control quality of the control system.

    ¢Ý The pressure control valve produces excessive noise. In industrial applications, control valve noise has become a major source of noise in industrial equipment. Therefore, reducing control valve noise has become an important research topic and has received attention from governments around the world.

    ¢Þ Pressure control valves are energy-consuming devices. In the current era of increasingly scarce energy resources, it is even more important to adopt energy-saving technologies to reduce the energy consumption of control valves and improve energy utilization efficiency.

2. Development direction of pressure control valve

    The development direction of pressure control valves primarily focuses on intelligence, standardization, miniaturization, rotatability, and safety.

    (1) Intelligentization and standardization. The intelligentization and standardization of control valves have been put on the agenda. Intelligentization mainly involves the use of intelligent valve positioners. The manifestations of intelligentization are as follows.

 ¢Û Digital communication. Digital communication will be widely applied in control valves. Based on the HART communication protocol, some valve positioners for control valves can transmit both input signals and valve position signals over the same transmission line. Based on fieldbus technology, control valves can be combined with valve positioners and PID control function modules to enable control functions to be implemented at the field level, thus dispersing hazards and achieving more timely and rapid control.

    ¢Ü Intelligent valve positioner. The intelligent valve positioner possesses all the functions of a valve positioner, and at the same time, it can enhance the dynamic and static characteristics of control valves, as well as improve the control accuracy of pressure control valves. Therefore, intelligent valve positioners will become widely used as important auxiliary devices for control valves in the coming period.

    Intelligent functions such as self-diagnosis of control valves and remote communication of operating status facilitate the management of control valves, make fault diagnosis easier, and reduce the skill requirements for maintenance personnel.

    ¢Ú Reduce product types and simplify production processes. The adoption of intelligent valve positioners not only facilitates the change of flow characteristics of control valves but also enhances the control quality of the control system. Therefore, the requirements for the flow characteristics of control valves can be simplified and standardized (for example, only producing control valves with linear characteristics). Using intelligent functional modules to achieve matching with the characteristics of the controlled object greatly reduces the types and varieties of control valve products, simplifies the manufacturing process of control valves, and enables them to undergo testing and recognition in production and the market.