Problem of hysteresis in the operation of direct-action safety valve

Introduction. A large proportion of direct-action safety valves open at given pressure, and close at lower pressure, forming a hysteresis loop. This effect is known from the test results for a long time. The reason for the occurrence of hysteresis is explained by comparing the gas dynamic forces acting on the moving parts of the valve and the force of the spring or load. Unfortunately, the comparison is made by a graph-analytic method that lacks gene­ral judgment. This could be overcome by describing the hysteresis loop analytically, but known mathematical models, including numerical ones, describe only its separate branches, whether it is the section of the loop at the moment of valve opening or closing.

Purpose of the research. To solve analytically the problem of constructing the hysteresis loop in the operation of direct-action safety valve.

Working hypothesis. Sharp movement of the valve head upwards from the seat to the stop in the limiter when the calculated pressure is reached in the protected volume and sharp movement of the head downwards to the seat when the pressure is reduced is the result of the head jumping from one stable position to another, bypassing the unstable part of the valve characteristic.

Method of the research. Theoretical, with the use of laws of gas dynamics, mechanics, stability theory and simi­larity theory.

Conclusions. The hysteresis loop in the operation of the safety valve, which represents the discontinuous function, can be described analytically. It is a set of stable sections of the equilibrium line of forces acting on the moving parts of the safety valve. Obtained from the condition of equilibrium of forces, the dependence of the valve lift height on the pressure in the protected volume quite adequately reflects the known experimental data.

It is also obtained that load valves organically have a large hysteresis loop, which by any means cannot be excluded. Spring valves also have a hysteresis loop, the size of which can be adjusted by changing the spring stiffness, including complete exclusion.

1. Weinberg Ya.I. Steam boilers. Causes of explosions of steam engines. Measures to prevent them. Moscow, Type. Potapova, 1888; 393. (rus).

2. Kondratieva T.F. Safety valves. 2nd ed., revised and additional. Leningrad, Mashinostroenie Publ., 1976; 230. (rus).

3. Gastberg A., Richter A. Betriebsverhalten von Sicherheitsventilen mit konstantem Fremdgegendruck. ARI-Armaturen GmbH & Co. KG, 2015. URL: www.ari-armaturen.com

4. Greenwood A. Tyco pressure relief valve engineering handbook. Crosby and Varec Products. Preliminary Edition. 2012. Fire Science Centre, University of New Brunswick, P.O. Box 4400, Fredericton, N.B. E3B 5A3 Canada.

5. Kondratieva T.F., Isakov V.P., Petrova F.P. Dynamic stability of the safety valve operation. Chemical and oil engineering. 1978; 12:14-17. (rus).

6. Dannenmaier T., Schmidt J., Denecke J., Odenwald O. European program on evaluation of safety valve stability. Engineering. Chemical Engineering Transactions. 2016; 48:625-630. DOI: 10.3303/CET1648105

7. Hős C.J., Champneys A.R., Paul K., McNeely M. Dynamic behavior of direct spring loaded pressure relief valves connected to inlet piping: IV review and recommendations. Journal of Loss Prevention in the Process Industries. 2017; 48:270-288. DOI: 10.1016/j.jlp.2017.04.005

8. Aldeeb A.A., Darby R., Arndt S. The dynamic response of pressure relief valves in vapor or gas service. Part II: Experimental investigation. September. Journal of Loss Prevention in the Process Industries. 2014; 31:127-132. DOI: 10.1016/j.jlp.2014.06.002

9. Borg A., Jakobsson S. On the stability of pressure relief valve. A numerical study using CFD Department of chemical and biological engineering division of chemical engineering. Gothenburg, Sweden. 2014.

10. Stadnik M.I., Shargorodsky S.A., Rutkevich V.S. Safeguarding the constant hysteresis of spool valves in the straight line. 2020; 4(111):100-107. DOI: 10.37128/2520-6168-2020-4-11 (ukr).

11. Berro H., Moussou P. Electricité de France research and development analysis in mechanics and acoustics dept mechanisms of instability of safety relief valves in water systems. 10th International Conference on Flow-Induced Vibration Trinity College, Dublin, Ireland July 5th 2012.

12. Plugin B.S. Study of the process of closing a pneumatic poppet valve and ways to reduce the speed of landing of the shut-off body on the saddle : abstract of the dissertation of the Candidate of technical sciences. Moscow, 1978; 16. (rus).

13. Lubenets V.D., Romanenko N.T., Nikitin Yu.F. et al. Determination of the opening time of electro-pneumatic valves. Compressor and vacuum machines and pneumatic units : tr. MVTU. 1971; 146:56-58. (rus).

14. Zong C., Zheng F., Qingye Li, Song X. Experimental analysis of the lift break of a spring loaded relief valve operating in pneumatic mode. Journal of Pressure Vessel Technology. 2020; 142(6). DOI: 10.1115/1.4047245

15. Makaryants G.M., Sverbilov V.Ya., Makaryants M.V., Batrakova O.V. Calculation of the lifting force of a gas flow in a flat safety valve using numerical methods. Proceedings of the Samara Scientific Center of the Russian Academy of Sciences. 2010; 12(4):247-251. (rus).

16. Sverbilov V.Ya., Makaryants G.M., Makaryants M.V., Stadnik D.M. Analytical model of self-oscillations of a flat safety valve. Proceedings of the Samara Scientific Center of the Russian Academy of Sciences. 2010; 12(4):252-256. URL: https://cyberleninka.ru/article/n/raschyot-podyomnoy-sily-gazovogo-potoka-v-ploskom-predohranitelnom-klapane-s-ispolzovaniem-chislennyh-metodov (rus).

17. Gastberg A., Richter A. Betriebsverhalten von Sicherheitsventilen mit konstantem Fremdgegendruck. ARI-Armaturen GmbH & Co. kg. 2015. URL: www.ari-armaturen.com

18. Zahariev T. Berechnung der Durchstr¨omung und der Kennwerte von Sicherheitsventilen : Dissertation zur Erlangung des akademischen Grades Doktoringenieur. Fakultat fur Ver-fahrens-und Systemtechnik der Otto-von Quericke-­Universitat Magdeburg, m 15.11.2001. (ger).

19. Rocek J. Schnelschub — Sichercheitsventil. Technische Information Armaturen. 1967; 2:23-26. (ger).

20. Polandov Yu.Kh. Improving the explosion safety of steam boilers with a working pressure of up to 0.07 MPa in the agro-industrial complex by engineering solutions : abstract of the dissertation of the Candidate of technical sciences. Eagle, 1998; 43. (rus).