Help - How do I Chemically Convert Fluids?

Hi,

In my model I have gases as fluids, where the unit is kg/hr.

My gases are methane (CH4) and carbon dioxide (CO2). I usually have >70% methane (combustable) and <30% carbon dioxide (inert).

I extract these two gases from wells, and pass them along pipes.

Question: How can I model a process that combusts the methane in two different situations?
1. Flaring: Where a percentage (e.g. 95% combustion efficiency) of the methane in the stream is combusted with ambient oxygen to form carbon dioxide, and any CO2 in the input stream passes straight through
2. Generation: Same as flaring but, in addition, electricity is produced by the combustion according to the energy in the methane multiplied by an efficiency of generation

My ultimate aim is to count up the total CO2 produced by both processes as the methane flows through it, although counting the electricity produced is also useful.

The issue lies in the fact that combusting brings a mass conversion, as follows: The molecular mass of carbon=12, oxygen=16 and hydrogen=1.
Thus 1 mole of CH4=16kg and 1 mole of CO2=44kg.

CH4 + 2O2 -> CO2 + 2H2O
16 + 2(32) -> 44 + 2(18)

Thereby combusting 1kg of CH4 makes 44/16 kg of CO2. So I need someway of converting a stream of incoming CH4, into a heavier stream of outgoing CO2, so the mass is not conserved.

One possible way may be to have a separate source of oxygen (i.e. not using ambient oxygen), which enables mass conservation, but then it means I have to deal with the water, and extra fluid generators.

How can I best model this situation?

Please help

Wits end

EXAMPLE: If the available gases in 1 hr are 20kg of CH4 and 1kg of CO2, and the combustion efficiency is 95% then,
- 19kg of CH4 are combusted into 19*(44/16) kg of CO2
- 1kg of CO2 is passed straight through
- 1kg of CH4 is not combusted and passes straight through
If the heat of combustion of CH4 is 891kJ/mol and the generation efficiency is 30% then the electricity produced by the 19kg of CH4 is,
- 19*(1/16)*0.3*891 kJ of electricity, which is then converted into Watts based on time