Explosion Protection

Safety Concept for Coal Pulverising Plant

30.11.2009 | Editor: Marcel Dröttboom

In order to minimize the residual risk in the case of special operating conditions, the Zementwerk Rohrdorf, Germany, chose a strategy that, in addition to partial neutralization measures, also relies on structural measures to keep possible explosive events at a calculable level.

The cement industry often uses coal as fuel, which is delivered in bulk and then pulverized and dried prior to the combustion process. This results in an increase in reaction surfaces that create an explosive atmosphere in combination with oxygen. When impurities that can produce sparks are introduced into the pulverizing process, they create potential ignition sources for an explosion.

The safety concept developed for this application by Scheuch, which has successfuly passed examination by the TÜV, by the FSA, and by Mr. Dipl.-Ing. Böckmann from Inburex, has the important advantage of using only a single pressure relief vent in comparison to other variants.

Besides lower costs, another factor that spoke for this solution was the fact that a second relief vent immediately downstream from the mill could not have been implemented with the required explosion protection zone in the direct vicinity of the rotary kiln for technical reasons. With the delivery of a new Impuls bag filtration system to replace an existing electrostatic precipitator, Scheuch has also created a comprehensive safety concept for the pulverizing plant’s dedusting system.

The filter discharge process takes place using an ATEX-certified rotary valve. The valve, which is safety rated against flame penetration up to 1 bar, has a pressure surge strength of 10 bar and serves as an explosion decoupling system.