Controlling emissions from process industries and district heating plants generally leads to increased energy consumption and higher costs. To be sure, the pollution burden is lessened, but nobody gains when heat is released to the great outdoors. However, an integrated pollution control system that also recovers heat achieves the dual goals of environmental clean-up and energy efficiency.
Such systems mean that investments in pollution control can be at least partially recovered with lower energy costs, and in some cases may even be profitable. The technology is particularly interesting in heating systems that burn biofuels such as peat, wood chips or waste paper, because that’s where you have large amounts of steam in the effluent gasses along with high levels of latent heat.
Sweden’s Radscan Intervex manufactures integrated equipment designed to clean up exhaust gasses and at the same time recycle energy back to the district heating network. “Our technology recovers emissions equivalent to the climate-affecting releases from 200,000 private automobiles a year”, says Gunnar Råbe, the majority owner of Radscan. “Our customers have increased their energy production by 470 MW. That’s almost as much as a standard nuclear reactor.”
Radscan Intervex employs technologies that have been in use for nearly 20 years, since the days when the threat of a warming climate was less understood than it is now. With growing interest in biofuels, wild swings in fossil fuel prices and greater public awareness of environmental risks and opportunities, demand for those technologies is steadily increasing. Flue gas condensation with integrated energy recovery is widely used in industries that generate heat and electricity from wood products and household waste, including power plants, district heating systems and pulp factories.
A few years ago Radscan constructed the world’s largest flue gas condensation installation in Uleåborg, Finland, producing 55 MW of electricity. An even larger plant is under construction in Södertälje, Sweden.
Cleaning polluted process air
Radscan’s concept of combined pollution control and energy recovery is also applicable to exhaust gasses from process industries containing particulates, oils, volatile organic compounds (VOCs) or other chemical substances. Even highly viscous pollutants can be treated.
Microscopic droplets (aerosols) of hydrocarbons, partially combusted petroleum, vulcanization products, silicone, amines, terpenes and other compounds can be separated from flue gasses by electrostatic filters, which charge the aerosol particles and capture them on collector plates.
About flue gas condensation and energy recovery
Wood-based fuels contain relatively large quantities of water, which causes energy to be lost as steam. Radscan’s technology is based on cooling the exhaust gasses at the same time they are “scrubbed”. The water vapour condenses, liberating latent energy which can be captured for productive use. If a plant is connected to a district heating network, the heat can be put to domestic uses.
Published in Januari 2009