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Problems in the application of pressure control valves

- Aug 15, 2018 -

1. There are many varieties of pressure control valves, many specifications and many parameters. The pressure control valve is suitable for the control requirements of different industrial production processes, such as temperature, pressure, medium characteristics, etc. There are nearly a thousand different specifications and different types of products, which makes the selection of the pressure control valve inconvenient, the installation and application is inconvenient, and the maintenance Inconvenient and inconvenient to manage.

2. The reliability of the pressure control valve is poor. The characteristics of the pressure control valve at the time of shipment are quite different from those of a certain period of operation. For example, increased leakage, increased noise, and poor valve reproducibility cause difficulties in long-term stable operation.

3. The pressure control valve is cumbersome, which brings inconvenience to the transportation, installation and maintenance of the control valve. Usually, the weight of the control valve is several times to several hundred times heavier than the weight of the general instrument. For example, the control valve of a DN200 weighs 700kg. Transportation, installation and maintenance need to use some mechanical equipment to complete, and the application of the control valve It is inconvenient.

4. The flow characteristics of the pressure control valve do not match the characteristics of the controlled object of the industrial process, resulting in poor quality of the control system. The ideal flow characteristics of the pressure control valve have been determined at the time of shipment from the factory, but the characteristics of the controlled objects in the industrial process vary, and the pressure drop ratio on the force port changes, so that the control valve operating flow characteristics cannot match the characteristics of the controlled object, and the control system Control quality is degraded.

5. The pressure control valve is too noisy. In industrial applications, control valve noise has become a major source of noise for industrial equipment. Therefore, reducing control valve noise has become an important research topic at present, and has received the attention of governments.

6. Pressure control valve is energy-consuming equipment. In the current shortage of energy, energy-saving technology should be adopted to reduce the energy consumption of control valves and improve energy utilization.

The development direction of pressure control valve

  The development direction of pressure control valves is mainly intelligent, standardization, miniaturization, rotation and safety.

  The intelligentization and standardization of control valves has been mentioned on the agenda. Intelligent use mainly uses intelligent valve positioners. Intelligentization is reflected in the following aspects.

    1.The intelligent function of the self-diagnosis of the control valve and the remote communication in the running state makes the management of the control valve convenient, the fault diagnosis becomes easy, and the skill requirements for the maintenance personnel are also reduced.

    2.Reduce product types and simplify the production process. The intelligent valve positioner not only can easily change the flow characteristics of the control valve, but also improve the control quality of the control system. Therefore, the requirements for the flow characteristics of the control valve can be simplified and standardized (for example, only the linear characteristic control valve is produced). The intelligent function module is used to match the characteristics of the controlled object, so that the type and variety of the control valve product are greatly reduced. The manufacturing process of the control valve is simplified and tested and approved in production and in the market.

    3.digital communication. Digital communication will be widely used in control valves. Based on the HART communication protocol, some valve positioners for control valves implement input signals and valve position signals on the same transmission line; based on fieldbus technology, control valves and valve positioners The combination of the PID control function modules enables the control functions to be implemented at the field level, so that the dangers are dispersed and the control is more timely and faster.

    4.intelligent valve positioner. The intelligent valve positioner has all the functions of the valve positioner, and can improve the dynamic and static characteristics of the control valve and improve the control precision of the pressure control valve. Therefore, the intelligent valve positioner will become an important control valve auxiliary device for some time to come. is widely used.

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