The regulating valve is the most common form in the production automation system actuators, in the production process of the application has spread to various industries, the regulating valve by the control unit outputs a control signal receiving adjustment means of power operated to control the pressure or flow of the fluid, plays an important role in the stable production, optimal control, maintenance and repair control.
Due to the harsh marine environment over land, the physical and chemical properties of the medium also vary widely, so choose safe, suitable, reliable and economic regulator valve to meet the process adjustment requirements and improve the level of control and prolong life, designers of most concern.
Regulating valve design and selection
Select the appropriate control valve, we must first determine the working conditions. Marine platform of CFD18-1 replacement pump outlet pipe outside diameter and wall thickness 4 〃 Sch160, regulating valve fluid seawater valve inlet pressure 11500KPaA outlet pressure 300KPaA, before and after the large pressure difference, the largest flow of 80m3 / h, design temperature 39 ℃, the following describes the selection process.
Regulating valve actuator
The regulating valve power source categories in accordance with the implementing agencies for the pneumatic control valve, electric control valve, hydraulic control valve and the hybrid regulator valve four classes. According to the analysis on working conditions, the pressure valve before the seat structure oriented choice of valve in the form of direct balance-oriented valve. On the other hand, CFD18-1 offshore platform instrument air, hydraulic control less efficient, so choose the electric actuator. Regulating valve flow characteristics
Flow characteristics With the opening from 0% to 100% change through the relationship between the flow valves and valve stroke. The flow characteristics of the common ideal linear, equal percentage, parabolic and quick opening four. Parabolic flow characteristics equal percentage flow characteristic closer to the former with the latter instead, features quick and is mainly used for position control and sequence control, thus the choice of the flow characteristics are generally limited to linear features with an equal percentage characteristics choice. In CFD18-1 project, the the upstream pump outlet pressure basic setting downstream pressure 300KPaA, essentially constant differential pressure regulating valve so I chose the linear characteristics. Regulating valve diameter selected
Caliber is too small technological object requires the maximum flow control valve will not pass, or the increase in energy consumption; diameter is too large, not only increased investment, and often work under the conditions of the small opening of the regulating valve, adjustable ratio decreases regulation performance deterioration is likely to cause instability in the control system. Caliber choice and the main basis for the valve flow capacity CV.
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