Due to the characteristics of the charged raw materials, the off-gas generated in shaft furnaces not only has a high dust loading, but also contains SOx’s and volatile organic components. To be able to utilise the high calorific CO component of the gas, these must be removed. The cooling of the gas and removal of the unwanted components requires a robust and reliable technology using proven equipment.
The scrubbing of gases using the THEISEN-Disintegrator based technology is successfully applied at many shaft furnaces, including cupola furnaces producing cast iron, blast furnaces producing pig iron, IS-shaft furnaces for the combined production of zinc and lead using the Imperial Smelting process as well as Oxicup furnaces where pig iron is extracted from waste material generated in the steelmaking industry.
The cleaned off-gas is used to generate the hot blast in stoves with downstream recuperators. The balance of the gas is available for electricity generation using turbine generator sets.
The highly efficient gas cleaning must comply with the requirements of the production process and equally also guarantee compliance with the emissions limits.
The THEISEN Gas Cleaning Plant for shaft furnaces consists of the following main components
- Counter Flow Gas Cooler for gas cooling and primary dust removal of large particles
- THEISEN-Disintegrator for final scrubbing and compensation of internally generated pressure losses
- Water Separator to remove the dust laden process and cooling water from the cleaned gas
- Overflow Valve isolating the gas cleaning plant from the stack head
- Non-Return Valve to the consumer network
- Furnace Pressure Control to ensure the controlled drafting of the furnace gases
The multi stage cleaning system not only ensures that the solid particulate matter conforms with the requirements, but also removes SOx‘s which are captured by the process water. The associated process water plant removes the suspended solid matter, cools the water and adjusts the pH before returning the water to the gas cleaning plant.