Abstract: With the rapid development of science and technology, the production of chemical products has also been transformed to the direction of automation and intelligence. Valve, as the key structure of chemical system, plays an important role in the whole system. Chemical products produced by the business as flammable, corrosive and other characteristics, the risk of accidents is extremely high, the chemical industry in the past mostly used in the production process for the closed process, in order to achieve the purpose of preventing chemical accidents. But only to enhance the choice of the valve can be a high-level solution to such problems. In this process, due to the wide range of valves, different valves also differ in their functions. At the same time, the valve is an important component of the chemical system. The quality and function of the valve will have a significant impact on the operation of the chemical system. In order to ensure the stable operation of the chemical system, you need to master the valve selection skills, and based on this selection based on the appropriate valve, so as to ensure the continuity and safety of chemical production. Therefore, chemical design should be based on the actual operation of the system to select the appropriate valve to ensure that the valve of reliable quality, good performance, so as to chemical system stability and safe operation of laying a solid foundation for chemical companies to create more economic benefits. Based on this, this article mainly analyzes the selection techniques of the commonly used valves in chemical design, for reference only.
Keywords: Chemical Design; Common Valves; Selection Tips Introduction Valves are widely used in chemical design piping systems, the pipeline can be a direct impact on operational status, the actual operation of the pipeline to determine the effect and safety, so choose the right type The valve has become the chemical industry's primary choice when thinking about the valve. In order to ensure the rationality of chemical design, research on valve selection principles and skills is necessary.
The importance of the selection of a valve Science and technology continue to make the type of valve increased significantly, the current chemical companies commonly used valves, mainly for the
relief valve , emergency shut-off valve,
throttle ,
check valve and
gate valve, etc. , Different types of selection of the key points are not the same. Some chemical in the production process, due to ignoring the valve type and material selection, resulting in inefficient production or even a major safety incidents, the analysis can be found mainly due to not grasp the key points of the valve selection. By considering the chemical production requirements as well as the characteristics of the valve, the first choice of the valve should be clear when its applicability, to ensure that the valve switch mode of operation, working pressure and other chemical equipment to match the needs of the device can be determined. In the choice of different types of valves, you need to follow the characteristics of different valves, advantages and disadvantages and application conditions, to determine what type and material of the valve; also need to consider the valve port connection applications.
2 common types of valves introduced 2.1
globe valve Shut-off valve is closed down the valve, the stem is a power plant, can drive the valve to a specific trajectory to achieve the role of regulation. Globe valve is simple in structure, low in price and convenient in maintenance. It is widely used in chemical pipelines. At the same time, the cut-off valve also has some shortcomings, such as poor regulation performance, special requirements on the medium, the valve opens and closes, resulting in greater energy consumption.
2.2 Throttle valve Throttle valve is commonly used in chemical production of throttling components, the main function components for the valve flap, the rest of the structure and the globe valve is roughly the same. Throttle valve application advantages and disadvantages can refer to the globe valve.
2.3 Gate Valve The main components of the valve stem and valve plate, driven by the valve plate will be lifting movements. Although the valve closed well, has a strong regulatory function, but its larger, complex structure, maintenance time required for a long time, which in the chemical system has been greatly restricted.
2.4
butterfly valve Butterfly valve is in the role of the vertical rotation of the switch control in the pipeline from the main cut off and retain the role. Butterfly valve structure is simple, the environment has a strong adaptability, the control effect is also ideal.
2.5
plug valve Plug valve is driven by the stem to make the plug body rotation, so as to achieve the purpose of opening and closing the pipeline, with a good seal l, sensitive control, fast response, low noise and so on.
2.6
Diaphragm valve Diaphragm valve construction and working principle and other valves have obvious differences, the use of rubber membrane and plastic film to achieve control functions, the application of diaphragm valve medium must contain hard suspended solids, while the pipeline pressure also has some restrictions .
2.7 Check Valve Check valve can make the pipeline medium to maintain a single direction of flow to prevent the media backwards for corrosive media and high pressure pipe can also be used for chemical sewage treatment system with high economic value and practical value.
3 different types of valve selection principles For the current complex valve classification and complex conditions, to select the type and material suitable valve products, we must have the valve characteristics of proficiency, and the valve selection steps, basis and use of principles Make your choice. Valve selection principles are as follows: For the flow resistance of small direct-flow valves, and more as a medium for the opening and closing of the valve used; if the purpose of controlling the flow, you can choose to regulate the flow of the valve;
Ball valve and plug valve; if the media for the suspended particles can be used to close the sliding member along the sealing surface with a wipe valve.
4 chemical design commonly used valve selection skills 4.1 clear the valve function, the use of the valve positioning Chemical pipeline design, the pipeline involved in the valve, the need for a clear function, the use of the valve to locate in this Under the circumstance, it is necessary to further clarify the selected valve to play its role, at the same time a full understanding of the selected valve control methods, working pressure, through the familiar control of the selected valve function, and thus to a certain extent, according to chemical tube The actual situation of the road to choose the right valve.
4.2 Familiar with the characteristics of the valve In the valve market, due to the different functions of the valve, so the type of valve there will be some differences. For different types of valves, whether it is the characteristics, or production and application, there will be more or less some differences, based on this, in the chemical pipeline design, valve characteristics need to be considered, we must be clear The type of valve selected, to avoid the use of unreasonable valves, thereby affecting the safety of chemical pipeline operation, reliability.
4.3 The consistency of the valve port In the chemical design process, the valve selection, we must pay attention to the consistency of the valve port to ensure that the valve can be used properly connected to effectively ensure that the valve in the chemical design process full Play its role.
4.4 Attention to the quality of the selected valve In order to ensure the normal operation of chemical pipeline in the design of chemical process, we must attach great importance to the quality of the selected valve, the valve material to complete the strict checks, the effective control of the house due to material constraints The problem of the valve quality, to ensure the normal operation of chemical pipelines. In addition, the valve selection, the valve must be on the flow and pressure and other factors to complete a comprehensive analysis to prevent the use of the valve function.
5 Chemical Design Valve Selection Strategy Commonly used in the selection of the valve technology, its application to chemical design practice, in order to improve the chemical design of advanced and scientific. Gate valves are usually prioritized when selecting the most commonly used chemical design valves because of the wide range of switching mediums used in gate valves. In addition to being used in pipes that use steam and oil as medium, they are also suitable for other media, And the gate valve in chemical production and chemical system operation applications with other valves can not match the application advantages. In the chemical design, the selection of the cut-off valve should first pay attention to the scope of application of the cut-off valve to consider, the cut-off valve is more suitable for some of the less demanding fluid resistance chemical pipeline, in particular, some small chemical pipeline Valve can choose to use the globe valve. Shut-off valves can be used to regulate the pipe flow and pipe pressure, but the adjustment accuracy is not high. Throttle valve is generally used in medium temperature and pressure conditions are high environment, and more for the regulation of flow and pressure control, it should be noted that the chemical design for the throttle valve can not be used as a cut-off valve. In addition, in the chemical design, for the plug valves and butterfly valves, the choice of check valve use, should also be based on their respective scope of application, combined with the valve characteristics of the application, the scientific and rational choice of design and application.
In conclusion, the selection of commonly used valves in chemical design not only determines the application value of the design scheme, but also is closely related to chemical production. When choosing commonly used valves, it is necessary to strengthen the collection of valve data, scientifically analyze chemical systems and valves, Develop a sound valve selection program to ensure that the valve of good quality and application of reasonable, can give full play to the role of regulation and control, so as to chemical production to provide a safe and reliable environment.
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