Is there a relationship between the degree of crystallization of ammonium salts and pressure?
Thread Content
As the title suggests, units for diesel hydrogenation or jet fuel hydrogenation generally have a process of injecting water before reactor air cooling. I would like to ask that in some jet fuel processing units where the system pressure is below 2.0 MPa, this water injection process is not implemented; does this mean that ammonium salt crystallization is related not only to temperature but also to the pressure conditions?
It is closely related to the reaction pressure. Taking ammonium chloride crystallization as an example: within the tube bundle of the heat exchanger, as the temperature drops, the vapor pressures of NH3 and HCl in the process medium increase accordingly. When their product Kp exceeds the equilibrium constant K1, ammonium salt crystals form. The formation of these crystals leads to an increase in pressure drop at that location, a reduction in the flow area, and a decrease in temperature there, which in turn results in more crystal formation. This creates a vicious cycle that gradually leads to complete blockage of the tube bundle in that area.
The system pressure is only 2.0 MPa; what is the reaction temperature? Is there a hydrogenation denitration reaction under these conditions?