Safety valve and piping issues in steam pipelines
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The steam pipeline is equipped with a spring safety valve for overpressure protection, but the exhaust must be directed to a vacuum vessel; to protect this vessel, a temperature and pressure reduction device is required, as shown in the diagram. Could such a setup cause problems with emissions, and could the back pressure behind the safety valve be too high, leading to issues such as frequent valve operation? Additionally, when calculating the dynamic back pressure behind the safety valve, if the valve’s opening pressure is 3 MPa and the absolute pressure in the container is 0.05 MPa, then the pressure needs to be reduced to 0.05 MPa through temperature and pressure reduction. In this case, how is the dynamic back pressure behind the safety valve calculated?
I’m a beginner in design, but from a production perspective, safety valves for medium and low-pressure steam are generally connected to allow steam to be released directly into the atmosphere. There are also cases where medium-pressure steam systems use pressure-reducing and temperature-raising devices; in such systems, the safety valve is connected to a large container at atmospheric pressure, with an outlet hole at the top of that container
What if a pilot-operated safety valve is chosen?
It doesn’t seem right; the relief system is meant to quickly reduce pressure in the pipeline in order to ensure safety. If temperature and pressure control devices are added later, it will increase resistance and reduce the rate of pressure drop, failing to serve a safety purpose
May I ask the original poster, what were the considerations behind doing this?
The steam needs to be recovered; it condenses later. Now consider using a safety valve (pilot-type) or electrically driven valves (controlled by signals)
Is the pressure released by the safety valve of steam pipes also recovered? Isn’t it better to not install a temperature and pressure reducer on the pipeline? It’s much easier to adjust that way
The safety valve is designed to ensure safety by preventing overpressure. There are some issues with the current design: 1. The safety valve should not activate frequently; if it does, it indicates a problem with the design of the steam pipes. 2. Under normal conditions, the amount of steam discharged by the safety valve should be small, so there is little value in attempting to recover that steam. 3. The current design approach may pose a risk to the safety of the steam pipes, and such a design is not recommended