Pratap
28-08-2021, 06:54 AM
Hello All,
Preamble: I am in the middle of Commissioning a R717 Screw Refrigeration System with a Thermosiphon Oil Cooler. I currently have a problem of high discharge pressure in the Evaporative Condenser which is higher by 3 barg than it should have been for which I seek help from this forum. (Current 14 barg, expected 11 - 11.5 barg).
The Thermosiphon Cooling I have used is slightly different from the standard P&ID used. In that, I have drawn a pipeline directly from the Evaporative Condenser (6 meters above the Oil Cooler) to the Oil Cooler rather than through a Priority Vessel with a tapping to the HP Receiver which is placed at a height of 1.5 meters from the Oil Cooler. The refrigerent is vented out into the reciever which is at a height of 1.5 meter from the Oil Cooler. The receiver is equilized with the Inlet of the Condenser.
The idea behind doing this was to use the entire 5-6 meter height between the Oil Cooler and the Condenser to generate more gravity pressure to cool the oil which I thought would improve the cooling in the Oil Cooler due to higher velocity. With this arrangement, I don't have a problem with the temperature of the oil, however the Condenser Pressure is higher by 2-3 barg.
An increase in the Discharge Pressure was anticipated, so a tapping was taken to the bottom of the receiver to collect the excess refrigerant into it directly thinking it would free the condenser coils of the liquid due to the pressure drop in the Oil Cooler, but this doesn't seem to be working. The Discharge Pressure remains the same even when I open the valve to the receiver.
Attached is the P&ID for your understanding. I wish to have an opinion on where I have gone wrong and what could be a possible solution to this issue I am facing.
Regards,
Pratap
Preamble: I am in the middle of Commissioning a R717 Screw Refrigeration System with a Thermosiphon Oil Cooler. I currently have a problem of high discharge pressure in the Evaporative Condenser which is higher by 3 barg than it should have been for which I seek help from this forum. (Current 14 barg, expected 11 - 11.5 barg).
The Thermosiphon Cooling I have used is slightly different from the standard P&ID used. In that, I have drawn a pipeline directly from the Evaporative Condenser (6 meters above the Oil Cooler) to the Oil Cooler rather than through a Priority Vessel with a tapping to the HP Receiver which is placed at a height of 1.5 meters from the Oil Cooler. The refrigerent is vented out into the reciever which is at a height of 1.5 meter from the Oil Cooler. The receiver is equilized with the Inlet of the Condenser.
The idea behind doing this was to use the entire 5-6 meter height between the Oil Cooler and the Condenser to generate more gravity pressure to cool the oil which I thought would improve the cooling in the Oil Cooler due to higher velocity. With this arrangement, I don't have a problem with the temperature of the oil, however the Condenser Pressure is higher by 2-3 barg.
An increase in the Discharge Pressure was anticipated, so a tapping was taken to the bottom of the receiver to collect the excess refrigerant into it directly thinking it would free the condenser coils of the liquid due to the pressure drop in the Oil Cooler, but this doesn't seem to be working. The Discharge Pressure remains the same even when I open the valve to the receiver.
Attached is the P&ID for your understanding. I wish to have an opinion on where I have gone wrong and what could be a possible solution to this issue I am facing.
Regards,
Pratap