How does flue gas condensation work? Key process parameters?
Flue gas condensation is a process commonly used in the chemical industry and is an example of heat transfer. Flue gas condensation is used to recover and reuse heat produced during a process.
In the condenser column, cold liquid is sprayed into the hot gas. The water vapour in the gas condenses when it reaches its dew point and releases latent energy during the phase transfer to from gas to liquid. This leads to an increase in the temperature of the liquid. A heat transfer from gas to liquid has occured. The energy in the heated liquid is then transferred to a heat exchanger or used in another part of the process.
Example - Combined heat and power plant
The combustion process in a combined heat and power plant generates electricity and at the same time heat, which is transferred in the process gas. To utilise the energy in the hot process gas, the gas is cooled in a heat exchanger or in a condensing scrubber. The heated water is then fed into a district heating network. The higher the moisture content of the fuel (e.g. biomass or household waste), the more heat can be recovered from the process. Some combined heat and power plants also use surplus heat from neighbouring industries, which is transferred into the local district heating network.
Which process parameters are important when designing a scrubber for flue gas condensation?
- Desired effect, and the system as a whole
- Temperature - inlet and outlet gas and liquid flow
- Gas flow
- Gas properties
- Relative humidity (RH)
- Dimensional constraints
- Pressure and pressure drop