Hearth furnace coke (HOK) adsorber for easy and highly efficient dioxin and mercury deposition

Minimizing pollution – efficiently and safely

The HOK-adsorber is a fixed bed reactor which operates according to the counterflow principle. It can be used in particular for cleaning of “moist” or “wet” exhaust gases. The adsorber is operated below the dew point, the hearth furnace coke is moistened during operation. Thereby, in contrast to the “dry” operated carbon filters, the occurrence of so-called “hot spots”, and thus the risk of fire or explosion within the adsorber can be surely excluded. An installation of equipment for fire detection and fire prevention and fire fighting is thus not required.

Advantages of the wet operation at a glance:

• No exhaust gas heating,
• no minimum throughput of exhaust gas,
• no inertisation of the adsorber,
• no CO measurement.

Minimizing pollution – easily and economically

Depending on the amount of exhaust gas the adsorber consists of one or more modules which are subdivided into several cells. Small amounts of hearth furnace coke are withdrawn at certain time intervals by pipes installed at the bottom of the adsorber cells. The loaded HOK/dust layer sags to a non-perfused adsorber section and is replaced by the less laden adsorbent inflowing from above. The withdrawal is done during operation.

In order to avoid harmful breakdowns a sufficiently large HOK-minimum layer can be found in the cells. In addition, a further amount of HOK, the consumption layer, is filled into the cells. Only when this amount is depleted by a series of withdrawals, fresh hearth furnace coke is refilled. The filling of single adsorber cells with furnace coke can be performed during operation.

The HOK adsorber can be installed as a separate, compact unit next to an existing system without affecting the operation. The changeover/conversion times are short.

Proven high deposition – the benefits at a glance:

• High deposition rate for dioxins/furans (> 99%) and mercury
• Insignificant inspection/maintenance costs
• Low adsorbent cost

The HOK adsorber has proven itself very well in practice, and is characterized in addition by minimal operation instructions and a high reliability, especially by the very high degree of deposition of pollutants and diverse odors, dust and clean exhaust gas pollutants.