EXPLOSION SAFETY FOR MILLS
by Sandra Fuchs, REMBEÂŽ GmbH Safety + Control, Germany
t is in the nature of a mill to have metallic parts that collide with one another at high speed, so that ignition sources are highly probable. Again, this is a closed container with a high concentration of dust, which may include oxygen, making an explosion extremely likely. Many mill manufacturers therefore offer their machinery in a design that is resistant to explosion pressure (up to 10 bar). Depending on the size of the mill, this may be very expensive for the operator. Alternatives would be flameless venting solution. In either case a decoupler should be attached both above and below the mill.
One particularly smart solution for the air intake of the mill is to install a Q-Rohr LF. This is a modified version of the Q-Rohr, well known in flameless venting, which does not contain the explosion vent that is normally included. As a result, it is possible to aspirate air under normal operation, and the air can then be fed through the stainless steel mesh filter without any trouble. If an explosion occurs, this filter removes the resulting heat and protects the environment from the flames and the explosion pressure.
In a production facility, pipelines always connect the individual parts of the plant. The purpose of explosion isolation is to ensure
Figure 1a and 1b: Quench valves, open and closed
76 | August 2017 - Milling and Grain