I am a fourth year chemical engineering student and for my design class I'm designing a low oxygen inert gas generation system for well stimulation. The design of my system is such that the engine driving my compressor is also feeding the compressor with a mixture of exhaust gas and nitrogen from a membrane unit. My question is what do I have to know about my compressor to choose my engine.

I know the power requirement but I was told that I also need to know the torque requirement of the compressor. I'm not too famillar with the mechanical aspect of engines so any help would be appreciated. Thank you

Chris