How-to control the downstream temperature of a JT valve by opening or closing the valve.
There are four variables:
- valve opening
- Upstream Pressure
- Downstream pressure
The pressure difference 2)-3) is proportional to temperature drop dT
Now you need to consider which variables are independent (controllable) and which are dependent:
2): Most likely dependant - if your valve closes pressure goes up?
3): Most likely fixed by valve downstream the separator or floating on export pipeline pressure (will not change fast)
4): Dependent on valve opening
In this case controlling the valve opening by using the valve upstream the cold separator will cause the upstream pressure to increase and the flow (most likely) to decrease in increased upstream pressure affects well operating conditions. This may be OK - and then you scheme will work
There are many things that I dont know about your system - but the main thing to consider is that controlling dT is actually controlling dP-