Spray Fan System

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CDC's spray fan system, comprising directional spray blocks backed up by a high pressure water system, attacks the coal dust, as well as methane, at source - namely the coalface. 

The directional spray blocks, which are placed at strategic points on the cutter boom and on the front of the CM, perform four vital functions:

Spray blocks are manufactured with either fixed spray nozzles, which are unscrewed for cleaning, or with reversing nozzles, which can be reverse flushed for quick and easy cleaning.

The system is required to deliver a minimum of 120 litres of water per minute at a pressure of 40 bar. The pressure is made up of 20 bar required at the spray blocks and up to 20 bar to overcome system resistance in the pipes and fittings and the pressure drop across the filters.

Reverse flush filter and on/off valves

The first filter in the system is a combined on/off valve and reverse flush filter, which is installed on the incoming line to the pump. It is operated by a ratchet with a positive locking point and once switched off, has to be rotated through the complete reverse flushing cycle before it can be switched on again.

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High pressure filter

A second high pressure filter is required in the system and is fitted before the spray blocks to filter out any particles which originate from either the pump or the system and this filter is manually back flushed.

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Booster pump

Booster pumps come in two different types depending on incoming water supply pressure.

Where the incoming water supply can maintain 120 lit/min at a pressure of between 15 and 20 bar, then a multi-stage centrifugal pump will be sufficient to raise the pressure for the spray fan system. The CDC six-stage centrifugal pump is a highly efficient unit mounted on a sturdy base frame and driven by an hydraulic motor. Prior to the fitting of a centrifugal pump, our support engineers will test the supply water pressure and volume to ensure that it is in fact the correct unit to fit.

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Generally, a high pressure positive displacement pump is required to meet the requirements for the spray fan system. The Myers D35 piston pump has been supplied to the industry for many years and has earned a enviable reputation for ruggedness, reliability and suitability.

It is now also joined by a Myers C35 pump which delivers the same performance as the D35, but is an indirectly driven unit, which results in a smaller more compact unit with lower capital costs and lower maintenance costs.

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