Fire-protection guidelines for Conveyors transporting coal

 

 

Conveyor systems in general have a fire risk due to external events and equipment failure. However the flammable nature of coal including the ability of some types, such as PRB, to self ignite introduces an exceptional hazard requiring special consideration.

Recognizing this, Patol Limited has recommended a set of practices for safely preventing, detecting, and extinguishing fires on coal conveyors.

 

 

Patol Limited has developed recommended fire prevention practices and guidelines for conveyor systems that transport coal.

The guidelines defined here are not equipment specific, and are limited to conveyor belt transport mechanisms. Physical layouts of coal-handling plants vary significantly and considerations of storage in bunkers and silos is addressed in a separate document.

The guidelines are not comprehensive as their purpose is to recommend the general practices necessary rather than comprise a detailed operating procedure or engineering specification.

The guidelines provide information about two principal areas:

¨ Fire prevention

¨ Automatic fire detection & suppression

FIRE PREVENTION

Some types of coal have the ability  to self combust under certain conditions. One of the worst of these is Powder River Basin (PRB) coal  which can self ignite even in very small quantities and in very short time periods.

Even with less volatile types than PRB coal measures that reduce the possibility of fire occurrence are by far the most economic.

Expenditure on both ‘preventative design’ and ‘additional operational procedures’ provides the most effective use of financial resource. 

These actions can be considered to be ‘Good Housekeeping’.

Housekeeping means limiting dust accumulation, preventing spills and conducting effective regular clean up.

For example, float dust should be contained within transfer points, and spillage from belts must be minimized.

Conveyors should never be stopped and allowed to stand with an un-discharged load for an extended period.

The accumulation of coal below a conveyor provides fire fuel and can even result in spontaneous ignition.

Float dust either in the air or settled on static fixtures can in certain circumstances form part of the fuel mix for explosions.

Routine ‘clean up’ activity should form part of the Plant Operating Procedure.

As a minimum dust and spillage built up around rollers and bearings must be removed to prevent ignition from stalled hot rollers.

For volatile coals such as PRB, daily wash-down of conveyor housings and transfer towers is recommended.

Fixed wash-down systems, designed for 100% coverage, are commercially

available and when installed provide greatly reduced labour costs.

For optimum results these piped installations should be combined with Automatic Fire Suppression / Extinguishing Media.

Plants that have installed this form of integrated Fire & Cleansing hydraulic water-spray system, and operate it on a daily basis, report being satisfied with the  performance.

PRB coal  spillage at a conveyor tail