I have a 750 ml reactor and working volume is 300 ml. my working temperature is 350 C. By using ideal gas law i found at the pressure to be around 2 bar. But I need final pressure build up @ 350 C to be around 25Mpa in order to keep my solvent in liquid phase. So, how should i calculate the initial head space pressure required. I'm planing to use N2 gas for pressure build up
Not sure, if I got your question right - my answer is quite simple: Take the boiling pressure of water. At 350°C it is 165bar. If your pressure is higher, water will be liquid, if not, you will only get steam.
definitely my pressure is less than 165 bar. so how should i calculate the additional initial pressure required in order to keep in liquid state
Please check with the Saturated Steam Table online. As long as the pressure you provide from external resouse (e.g. compressed inert gas tank) is higher than the corresponding steam pressure, water will remain as liquid phase. Normally, researchers would like to choose 100-200 psi (0.69-1.38 MPa) as a initial pressure (supplied by the compressed gas tank) before the reactor begins to be heated up. When you heat up the reactor, the water temperature increase, correspondingly the pressure inside the reactor increase, and it will be higher than the saturated steam pressure (because you have supplied an external pressure, the mechanism is similar to a high-pressure cooker, and a chemical engineering student would learn this in the 2nd year of undergraduate studying). Therefore, you don't need to calculate the initial pressure.
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