How about the development and application of API standard safety valve? - 4

Release time:

2024-04-15

B performance and displacement test. The structure design of the flow passage of the safety valve has an important influence on its performance and displacement. API Std 526 specifies the size of inlet and outlet and flow passage of safety valve. The ratio of outlet area to flow passage area is 64.26 ~ 3.02, which is larger than that of JB 4.13 ~ 3.06, especially for the smaller one. According to the difference of structure, the performance and displacement tests are carried out. A large number of tests show that: a. the performance of the test device has an important impact on the performance of the safety valve. By comparing the test results of five specifications (11 / 2h3033k4, 34, 4m6) safety valves on different test devices, it can be concluded that the capacity of the test device has no effect on the set pressure and the start-up pressure of the safety valve. Only when the capacity of the test device is large enough can we judge whether the reseating pressure and mechanical characteristics of the safety valve meet the requirements. b. Compared with API Std 526 safety valve, JB safety valve with smaller outlet area has smaller displacement coefficient. The displacement tests of API and JB safety valves were carried out on the test equipment. The test shows that the smaller the outlet area of JB safety valve is, the smaller the discharge coefficient is. Generally, the discharge coefficient of JB safety valve is 0.8 ~ 0.9, while that of API safety valve can reach 0.98.

C back pressure test. The outlet back pressure of safety valve has great influence on its performance. Higher back pressure will affect the action performance and displacement of safety valve.

The back pressure is generated by the back pressure generator, and the back pressure is adjusted mainly by changing the orifice size of the back pressure regulator in the back pressure generator to regulate the outlet discharge back pressure of the safety valve. Through the back pressure test, two experiences are obtained: A. there is a critical value of discharge back pressure. If the value exceeds the allowable value, the mechanical performance of safety valve will be damaged, resulting in safety valve flutter and other phenomena, and the discharge process is unstable. b. The opening height of the safety valve decreases with the increase of the discharge back pressure. The existence of the discharge back pressure causes the decrease of the opening height and the decrease of the actual displacement of the safety valve.

2) Flow field simulation modeling research: although with the help of advanced performance test device, many achievements have been obtained in the aspects of safety valve action characteristics and displacement, but the experimental research has the problems of large investment, long period and limited method. Therefore, computational fluid dynamics (CFD) is applied to the basic theoretical research of safety valve. By using CFD software, three-dimensional flow models of some safety valves are established.