Flue gas condensation
Encyclopedia
Flue gas condensation is a process, where flue gas
is cooled below its water dew point
and the heat released by the resulting condensation
of water is recovered as low temperature heat.
Cooling of the flue gas can be performed either directly with a heat exchanger
or indirectly via a condensing scrubber
.
The condensation of water releases more than 2 gigajoules (555.6 kW·h) per ton of condensed water, which can be recovered in the cooler for e.g. district heating
purposes.
Excess condensed water must continuously be removed from the process.
The downstream gas is saturated with water, so even though significant amounts of water may have been removed from the cooled gas, it is likely to leave a visible stack plume of water vapor.
The heat recovery potential of flue gas condensation is highest for fuels with a high moisture content (e.g. biomass and municipal waste), and where heat is useful at the lowest possible temperatures. Thus flue gas condensation is normally implemented at biomass fired boilers and waste incinerators connected district heating
grids with relatively low return temperatures (below approximately 55 °C (131 °F)).
Flue gas
Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. Quite often, the flue gas refers to the combustion exhaust gas produced at power plants...
is cooled below its water dew point
Dew point
The dew point is the temperature to which a given parcel of humid air must be cooled, at constant barometric pressure, for water vapor to condense into liquid water. The condensed water is called dew when it forms on a solid surface. The dew point is a saturation temperature.The dew point is...
and the heat released by the resulting condensation
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....
of water is recovered as low temperature heat.
Cooling of the flue gas can be performed either directly with a heat exchanger
Heat exchanger
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...
or indirectly via a condensing scrubber
Scrubber
Scrubber systems are a diverse group of air pollution control devices that can be used to remove some particulates and/or gases from industrial exhaust streams. Traditionally, the term "scrubber" has referred to pollution control devices that use liquid to wash unwanted pollutants from a gas stream...
.
The condensation of water releases more than 2 gigajoules (555.6 kW·h) per ton of condensed water, which can be recovered in the cooler for e.g. district heating
District heating
District heating is a system for distributing heat generated in a centralized location for residential and commercial heating requirements such as space heating and water heating...
purposes.
Excess condensed water must continuously be removed from the process.
The downstream gas is saturated with water, so even though significant amounts of water may have been removed from the cooled gas, it is likely to leave a visible stack plume of water vapor.
The heat recovery potential of flue gas condensation is highest for fuels with a high moisture content (e.g. biomass and municipal waste), and where heat is useful at the lowest possible temperatures. Thus flue gas condensation is normally implemented at biomass fired boilers and waste incinerators connected district heating
District heating
District heating is a system for distributing heat generated in a centralized location for residential and commercial heating requirements such as space heating and water heating...
grids with relatively low return temperatures (below approximately 55 °C (131 °F)).
External links
- On Flue gas Condensation by Götaverken Miljö AB