The fuel gas to the generator will no longer has a low -400F dew point. As a result, expansion of the quantity of gas across the regulator will result in freezing of water and/or hydrate formation.
There are few options available to address this problem. They are:
- Heat the gas prior to expansion to avoid subsequent freezing and line sweating.
- Inject methanol into the gas prior to expansion to suppress solids formation.
- Install electric tracing on the fuel gas line near the regulator to prevent line sweating.
Heating the gas may be accomplished in a number of ways:
- Exchange the generator exhaust gas against the fuel gas. Two units are required.
- Partially reduce the pressure of the fuel gas across a new regulator - lowering the fuel gas temperature, then exchange produced gas against cool fuel gas to raise its temperature above its dew point. This option introduces additional operational complications into the system.
- Install a conventional line heater - a gas-fired water bath heater.
- Use generator jacket - water to heat the gas.
All above 4 options require a back up inhibitor injection system for start-up.
The cheapest and recommended option is to use a methanol system on the fuel gas line with electric tracing. This is the lowest cost alternative and is easiest to operate.