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).