Scheuch specializes in providing customized solutions for each individual application case to ensure the best combination of low investment costs and minimal operating costs.
Reduction of acidic pollutants (HF, HCL, SOx) using additives based on Ca (calcium) or Na (sodium), including in:
- Conventional one-step dry sorption (with a low or no recirculation rate), and in
- Conditioned dry sorption (with a high recirculation rate) – MaxSORP
- Minimizing PCDD/F (dioxins and furans), Hg (mercury) and Hg compounds using
- Activated carbon
- HOK (hearth-furnace coke)
- Brominated and/or enhanced carbons
Crucial factors when selecting the appropriate procedure and sorbents are:
- Process and flue gas parameters such as temperature, moisture and pollutant concentrations
- Current and potential future separation output
- Sorbent costs
- Ash and waste material disposal costs
- Upstream plants (such as pre-separators) and downstream plants (such as SCR plants)
- Space requirements
- Other factors
A typical Scheuch dry sorption plant consists largely of:
- In some cases: a pre-separator (cyclone, multi-cyclone or spark separator)
- Additive silo(s)
- An additive loading point with one or more injection lances
- A fabric filter for separation – plus an electrostatic precipitator in some cases
- In some cases: a recirculation unit
- Residual material silo(s)
The Scheuch MaxSORP plant primarily consists of:
- In some cases: a pre-separator (for example, an e-filter)
- A fluidized-bed reactor
- Additive storage and additive feed lines
- Bag filter
- Recirculation system and
- Waste discharge for the reaction products
The exhaust gas is fed into the entrained-flow reactor from below. The exhaust gas is strongly accelerated through a cylindrical pipe (Venturi effect) in the lower part of the reactor. Here, additives are added and a considerable proportion of the dust separated in the bag filter is recirculated. This recirculation is the key to the extraordinary separation performance of this process. After the nozzle there is a diffuser and the cylindrical part of the reactor, where the sorbents introduced are slowed down to the reactor speed and distributed throughout the entire height of the reactor. Using a fluidized-bed reactor makes it possible to inject water directly into the reactor container via nozzles using a high-pressure water system and to set the desired reaction temperature regardless of the sorbent quantity.
The high heating capacity of the recirculated dust means that the water is spontaneously vaporized on the surface of the dust, thereby wetting it within a layer that is almost molecular in nature. This process greatly improves the reaction conditions for the acidic exhaust gas components being separated (SO2, SO3, HCl, HF, etc.) without the formation of clumps. 80 % of the acidic components are chemically adsorbed in the circulating fluidized bed (during the entrained-flow phase), while dioxins/furans are largely adsorbed (over 80 %) in the filter dust layer on the filter bag.
That is why a certain amount of differential pressure on the filter bag is crucial to separation performance. In the MaxSORP plant, the preferred sorbent for the acidic components of the exhaust gas is calcium hydroxide (Ca(OH)2).