1. Control valve problems in the application ①control valve varieties, specifications and more parameters. Control valve to adapt to different industrial production process control requirements, such as temperature, pressure, media characteristics, there are nearly a thousand different specifications, different types of products, the control valve selection is not convenient, inconvenient installation and maintenance, maintenance inconvenient , Management is not convenient. ② control valve reliability is poor. Control valve characteristics at the factory and after a period of operation have very different characteristics, such as increased leakage, increased noise, poor valve reproducibility, to the long-term stable operation difficult. ③ control valve bulky, to the control valve transport, installation. Maintenance inconvenience. Typically, the weight of the control valve weighs several times more than a hundred times the normal instrument weight, for example, a DN200 control valve weighing 700kg, transportation, installation and maintenance require the use of some mechanical equipment to complete the application of the control valve Inconvenient ④ control valve flow characteristics and industrial processes controlled object characteristics do not match, resulting in poor control system quality. The ideal flow characteristics of the control valve have been determined at the time of delivery. However, the characteristics of industrial controlled process objects are different, and the pressure drop ratio is changed on the force port so that the flow characteristics of the control valve can not match the characteristics of the controlled object and the control system control Poor quality. ⑤ control valve noise is too large. In industrial applications, control valve noise has become the main source of noise in industrial equipment. Therefore, reducing the noise of control valves has become an important research topic at present, and has received the attention of all governments. ⑥ control valve is energy-consuming equipment, more and more energy shortage in the current, more energy-saving technologies should be used to reduce the control valve energy consumption and improve energy efficiency. 2. The development direction of the control valve The development direction of the control valve is mainly intelligent, standardization, miniaturization, rotation and safety. (1) Intelligence and standardization The control valve is intelligent and standardization has been mentioned on the agenda. Intelligence mainly uses intelligent valve positioner. Intelligent performance in the following areas. ①self-diagnosis of control valves, remote communication and other intelligent operating functions, the control valve to facilitate the management, fault diagnosis becomes easier, but also reduces the technical requirements for maintenance personnel. ② reduce product type, simplify the production process. The use of intelligent valve positioner can not only easily change the flow control valve characteristics, but also improve the control quality control system. Therefore, the control valve flow characteristics of the request can be simplified and standardized (for example, only the production of linear characteristics of the control valve) with the intelligent function module to achieve the characteristics of the controlled object matching, so that the type and variety of control valve products greatly reduced so that The manufacturing process of the control valve is simplified and tested and approved in production and in the market. ③ digital communications. Digital communications will be widely used in the control valve to HART communication protocol as the basis, some of the valve positioner control valve input signal and valve position signal in the same transmission line to achieve; based on fieldbus technology, control valves and valve positioner The combination of PID control function modules enables the control functions to be implemented at the field level to disperse the danger and make the control more timely and faster. ④ intelligent valve positioner. Intelligent Valve Positioner with all the features of the valve positioner, while improving the dynamic and static characteristics of the control valve and improve the control accuracy of the control valve, intelligent valve positioner will become an important control valve auxiliary equipment for some time to be widely used. Standardization of the control valve in the following areas. ①In order to achieve interchangeability, so that the same size and size control valve manufacturers can interchange, so users do not have to choose a manufacturer and spend a lot of time. ② In order to achieve interoperability, control valves manufactured by different manufacturers should be able to work with other manufacturers of products, no signal mismatch or impedance mismatch and so on. ③ standardized diagnostic software and other supporting software, so that different manufacturers of the control valve can run the diagnosis, the operation of the data analysis. ④ standardized selection process. Control valve selection is still very concerned about the design of self-control problems, the use of standardized calculation procedures, according to the data provided by the process, the correct calculation of the required control valve flow coefficient, to determine the piping and selection of suitable valve body, valve and valve Internals, etc., to standardize the design process, improve design quality. (2) Compactness In order to reduce the weight of the control valve, and to facilitate transportation, installation and maintenance, the following measures have been taken to make the control valve smaller. ①using small executive body. The use of lightweight materials, the use of multiple sets of springs instead of a set of springs, reducing the height of the actuator, usually, the fine pneumatic actuator composed of thin film pneumatic actuator than the same type of control valve to reduce the height of about 30%, the weight Reduce about 30%, while the flow capacity can be increased by about 30%. ② change the flow path structure. For example, the movement of the valve core is changed to the movement of the valve seat, the linear displacement is changed to an angular displacement and the like, so that the control valve has a reduced volume and a reduced weight. ③ using electric actuator. Not only does it reduce the air supply and auxiliaries required for pneumatic actuators, it also reduces the weight of the actuator. Fisher's 9000 Series Electric Actuators, for example, have a Model 20 height of less than 330mm, reducing the overall control valve (with digital controller and actuator) to 20-32kg. (3) Rotation Because rotary control valves, such as ball valves and the like, have the advantages of relatively small volume, smaller flow resistance, relatively large adjustable, better sealing performance, better anti-blocking performance and greater circulation capacity, Therefore, in the new varieties of control valves, rotary valves increase the proportion. Especially in large-diameter pipes, ball valves, butterfly valves and other types of control valves are widely used. From the products of foreign countries in recent years, the proportion of rotary valve applications is increasing year by year. (4) Security The safety of the instrument control system has been valued by all aspects. The requirements of the safety instrumented system (SIS) for the control valve are also getting higher and higher, as shown in the following aspects. ①control valve fault diagnosis and treatment requirements increase, not only to the control valve after the failure of the passive maintenance, but also to carry out preventive maintenance and predictive maintenance before the failure occurred. Therefore, the composition of the control valve of the relevant components for statistical analysis, and timely maintenance recommendations have become more important. ② on the emergency stop system or safety interlock system control valve, put forward timely, reliable and safe action requirements. Make sure these control valves are responsive and accurate. ③ for the control valve used in dangerous places, should simplify the certification process. For example, intrinsically safe fieldbus meters can be simplified to use the FISCO fieldbus intrinsically safe concept to simplify the certification process for intrinsically safe products. ④ with other on-site instrument safety similar to the safety of the control valve, flameproof technology can be used \ fire safety technology, safety and security technology, intrinsically safe technology, non-spark technology; fieldbus instruments, but also the concept of physical, Intrinsically safe concept, FISCO concept and non-flammable (FINCO) concept. (5) Energy saving Reduce energy consumption, improve energy efficiency is a development direction of the control valve. There are several main directions for development. ①low pressure drop ratio control valve. So that the proportion of the control valve in the entire system to reduce the pressure drop, thereby reducing energy consumption, therefore, the design of low pressure drop than the control valve is one of the development direction; another development is the use of low-impedance control valve, such as the use of butterfly valve, eccentric Rotary valve and so on. ② using self-control valve. For example, the direct use of pressure after the valve composed of self-force control system, the media used to control the energy of the valve to achieve post-pressure control. ③ using electric actuator control valve. Pneumatic actuators throughout the control valve operation process needs a certain pressure, although the consumption of small amplifiers can be used, but over time, the air consumption is still huge. The use of electric actuator, the change in the control valve opening, the need for electricity, when the required opening can no longer supply, therefore, from the energy point of view, the electric actuator than the pneumatic actuator has significant energy saving advantages. ④ using piezoelectric control valve. The use of piezo-controlled valves in smart electric valve positioners consumes gas only when the output signal increases. ⑤ with a balanced structure of the spool, reduce the actuator thrust or push torque, reduce the membrane chamber, reduce energy needs. ⑥ frequency control technology to replace the control valve. For high pressure drop ratio applications, if the energy consumption is great, you can use frequency control technology, the use of inverter to change the speed of the operating equipment, reduce energy consumption. (6) Protecting the environment The environmental pollution has become a public hazard. The pollution of the control valve to the environment mainly includes the control valve noise and the control valve leakage. Among them, the control valve noise pollution on the environment is very serious. ①reduce the control valve noise. Developed a variety of methods to reduce the noise of the control valve, including the design from the control valve flow path to the control valve trim, from the noise source analysis to noise reduction measures. The main design noise reduction control valve and noise control valve trim; rational distribution of pressure drop, the use of external noise reduction measures, for example, to increase the isolation, the use of mufflers and so on. ② reduce the control valve of air pollution. Air pollution in control valves refers to "run", "run", "drip" and "drain" of control valves, which not only result in the waste of materials or products, but also cause pollution to the atmospheric environment and sometimes cause personnel Casualties or equipment explosion and other accidents. Therefore, the development of control valve packing structure and packing type, the development of control valve sealing valve control valve will be an important research topic in the future. The development of high-tech science and technology, such as computer science, control theory and automation instrumentation, has promoted the development of control valves. For example, the development of fieldbus control valves and intelligent valve positioners, the realization of digital communication in control valves, etc. The development of control valves has also contributed to the development of other science and technology, for example, the study of anti-corrosion materials, the methods of weakening and reducing noise, the research of fluid dynamics and so on. With the development of fieldbus technology, the control valve will also be open, intelligent and more reliable. It will be more effective and more effective in control and will play a more important role in the modernization of our country. Other industrial automation instruments and computer control devices Together, the industrial process control function more perfect, control of the fine.