Can a control valve achieve a pressure release rate of 0.7 MPa/min?

The control valve can achieve a pressure release rate of 0.7 MPa/min! In the first 10 years, emergency pressure relief valves for hydrogenation units were generally implemented using control valves; however, an emergency pressure relief test was required. This test continued until the opening degree of the control valve was set at a certain value such that the pressure release rate reached 0.7 MPa/min. The output signal value from the DCS was recorded, and this value was kept constant. During emergency pressure relief, the control valve would simply open at this predetermined opening degree. But this method is not good; the cost of conducting pressure relief tests is too high, and multiple tests are required to achieve the desired release speed. Moreover, the leakage level of the control valve can only reach Class V. Due to the large pressure difference before and after the release valve, after several releases, the valve stem and seat are subject to erosion, which inevitably leads to a decrease in the leakage level of this method. As a result, the valve continues to leak hydrogen, with the leakage becoming more severe over time, causing waste of hydrogen gas. This plan is not good. Now, emergency pressure relief valves are replaced with ball valves or gate valves, with a flow-limiting orifice plate installed behind the valve; this orifice plate is used to control the rate of release, and its design requires calculations. This method is good: the leakage level of the relief valve generally does not worsen, hydrogen is not wasted, and usually only one verification of the relief speed is required before operation begins. If that doesn’t work, calculate the orifice plate based on the recorded discharge rate, and then enlarge or replace the orifice plate.