Safety valve exhaust silencer
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Recently, I encountered a problem: I purchased a steam exhaust silencer for a boiler safety valve. The operating pressure of this safety valve is 4.46 MPa. The manufacturer of the silencer stated that it should be designed based on this operating pressure, with a pressure drop of around 3.2 MPa. This means that the backpressure on the safety valve would be around 3.2 MPa, which should affect the valve’s ability to operate properly, right? (The back pressure exceeds 10% of the starting pressure), but the manufacturer says that safety valve exhaust silencers are designed this way. I’m not sure whether this silencer is functional; could anyone please help me out?
There’s a problem with this manufacturer; don’t even consider it. Generally, steam emissions are released directly into the atmosphere; in other words, the back pressure is considered to be 0 when calculating safety valves. A silencer can achieve a \"pressure drop of 3.2 MPa\", at which point the pressure relief valve comes into play. If adopted this way, your safety valve back pressure will be at least “3.2 MPa” – is that possible?
I consulted several manufacturers of silencers, and all of them said that the sizing of the silencer is determined based on the starting pressure. They said that all that’s needed is to provide the starting pressure, temperature, exhaust volume, and pipe size; nothing else needs to be considered. They have sold many such silencers without any problems. In short, it totally confused me
The manufacturer’s answer is basically correct. 1. Steam is discharged directly into the atmosphere; therefore, it is sufficient to know the \"start-up pressure, temperature, steam discharge volume, and pipe size.\" In this case, it is the inlet condition of the silencer ； Export conditions: Atmospheric. Knowing your geographical location allows one to check the atmospheric conditions. 2. In fact: it is an exhaust vent silencer; for those that are not for venting, the outlet conditions of the silencer must be specified. 3. The setting pressure of the safety valve (also known as the valve setting) can be used to calculate the maximum back pressure. For a normality (non-equilibrium) of 10% at constant pressure, it is generally less than the critical flow pressure of the gas. Based on this, the allowable pressure drop of the silencer can be calculated. 4. It can be calculated that the actual resistance of the silencer is lower than the set pressure of the safety valve. 5. The manufacturer claims that the backpressure of the silencer has dropped to 3.2 MPa, but this is incorrect.
I’ve been through this without understanding the principles behind silencer design. But I never understand why muffler manufacturers design them based on the discharge pressure of safety valves. Fortunately, it doesn’t matter.