Design of control valve selection teaching software based on simulation technology

3.3 Simulation of valve body
The flow characteristic curve of the valve body is divided into four types: linear, fast opening, parabola, and equal percentage. The flow characteristic of the valve is mainly related to the shape of the valve core and the manufacturing process of the manufacturer [2]. Therefore, the referenced function is obtained by interpolating the flow characteristic curve given by the manufacturer by taking points.
3.4 Method of joint simulation of actuator and valve body
The simulation of the actuator part of the regulating valve and the valve body part are combined to obtain the overall simulation function, as shown in Figure 6. Since the (l, Q) curve is provided by the manufacturer, l and Q are known values, and Ii is the input value. Therefore, l can be obtained from Ii under a certain step length by l=f(Ii), and the value of Q can be found through the (l, Q) curve, thereby obtaining the point set (Ii, Q). The final input-output curve is shown in Figure 7 (taking the 48-41000 series of Shanghai Automation Instrument Co., Ltd. as an example).

4 Simulation of control valve failure
In order to enable users to more truly understand the principles and phenomena of actual industrial and mining failures and to achieve the purpose of preventing them from happening, this paper has added a fault simulation link. On the basis of completing the simulation of the input and output relationship of the control valve, the control valve fault simulation is performed. The fault in this system is mainly caused by the change of simulation parameters. When a component in the control valve is damaged or worn, its corresponding constant will inevitably change, which will cause the transfer function of the control valve to change, and finally reflected in the input-output curve, thus forming a corresponding fault.
The relationship between variables and faults of various control valves studied in this software under the condition of other parameters being constant (partial) is shown in Table 1. For example, when the fault is set to bellows damage, the parameter becomes smaller, and the fault is manifested in the curve as a decrease in the slope of the input-output curve.
In the process of selecting control valves, this system realizes: (1) Users learn to select control valves or test them by themselves with or without help. (2) Users can test the selected control valve under different media and form a relationship curve between input current, voltage or pressure and output flow. (3) Users set faults and observe the fault phenomenon curve. This selection system can play a good teaching role. It has the advantages of economy, speed and safety. It is closely related to actual production and can warn of faults.
References
[1] Wu Chongguang. PSE process system simulation technology [M]. Beijing: China Petrochemical Press, 1998.
[2] Wu Guoxi. Use and maintenance of control valves [M]. Beijing: Chemical Industry Press, 1998, 9(5): 209-213.
[3] Sun Hongcheng, Li Dazi, Weng Weiqin. Process Control Engineering [M]. Beijing: Higher Education Press, 2006.
[4] He Yanqing, Qiu Xuanzhen, Yang Jie, et al. Control valve engineering design and application [M]. Beijing: Chemical Industry Press, 2005.