Wallstein Holding GmbH & Co. KG

Function of a Heat Displacement System

Heat Displacement System

The Heat Displacement System allows the extraction of a particular amount of heat from the flue gas upstream of the flue gas desulfurization unit. In contrast to the Heat Recovery System, the heat is transferred to the clean gas side downstream of the flue gas desulfurization unit to increase the clean gas temperature. A closed water circuit is also used here. The cooling process assures effective operation of the desulfurization unit, which is characterized by lower water loss. Furthermore, clean gas reheating ensures that the temperature reaches an adequate level before entering  the stack. This reheating process improves the exhaust of the gases to the atmosphere and allows a reduction of aerosols. In addition, the higher temperatures reduce the risk of corrosion in flue gas ducts and the stack.

The cooling as well as the reheating process of the gas is done by two separately-designed heat exchangers. Both heat exchangers are connected to the same water circuit, so that permanent heat exchange is ensured. Due to the use of two independent heat exchanger units, the system ensures leakage free heat transfer between raw and clean gas. During cooling of the flue gases, the acid dew point is reached. To satisfy the strict requirements concerning chemical resistance, high capability, high reliability and long lifetime, Wallstein developed the so-called AlWaFlon® tube material. These tubes are based on the fluoropolymer base material of our partner DuPont, Switzerland. Beside the corrosion resistance, the Wallstein HDS design has very low maintenance requirements. Wallstein products are not only beneficial for the power industry because they increase efficiency, they also contribute to the reduction of carbon dioxide emissions. Other advantages are the reduce of CO2 emissions and the increase of efficiency by saving primary energy and additional the corrosion protection of stacks, ducts etc. by reheating the air.