2019-07-24 11:28:48
Operating and maintaining dust safety equipment and systems is just as important as designing them correctly. We’ve rounded up the top maintenance tips for spark detection and extinguishing systems, as well as mechanical dust collectors, courtesy of GreCon and ProcessBarron.
Spark detection and extinguishing systems:
• Check the spray nozzles for excessive wear, material build-up and proper operation.
• The Y-strainer screen should be flushed clean on a regular basis and replaced if needed.
• During months in the freezing weather, ensure heat tape and insulation is installed and working properly to avoid any pipes freezing.
• After maintenance, ensure any supply ball valve that was closed for maintenance is then opened for normal operations.
Mechanical dust collector:
• Yearly casing inspection and cleaning: This includes evaluating the condition of all of the tube assembly parts for possible replacement. Every inlet/ outlet tube should be free of any plugging. Guide vanes are the most common wear item and each one should be reviewed. Any inlet/outlet tubes with holes must be replaced. Any holes in the tubesheets or casing must be patched, as the dirty and clean compartments must be kept airtight and separate. Make notes on any material build-up in a particular area or unusual wear patterns.
• Yearly hopper inspection and cleaning: This includes looking for evidence of fires and verifying no clinker build-up. Holes in the sidewalls must be patched and cracks in the welds must be repaired. Every time the access door is opened, the seal gasket material must be replaced. If a poke hole opening is present it must always be capped off and sealed while the unit is being operated.
• Yearly inspection/rebuild of the hopper rotary feeder/double dump valve: This includes the internal and external components. Every time an access panel is opened, the seal gasket material must be replaced. On typical biomass-fired boiler applications it is recommended that the airlock devices be rebuilt every two years.
• Monitor the pressure drop: Use instrumentation to confirm the pressure drop across the unit (inlet flange to outlet flange) is near the original design conditions. Mechanical dust collectors operate at optimum efficiency when sized for a pressure drop between 2.5 to 4.00 inches WG. A sharp increase in the pressure drop usually indicates internal plugging has occurred.
• Regularly evacuate hoppers: One of the most critical aspects to successful mechanical dust collector operation is making sure the hoppers are properly (and continually) evacuated. If a single hopper on a multiple hopper application plugs, the unit’s efficiency can be reduced by up to 50-75 per cent. If possible, hoppers must be monitored on a daily basis to ensure there is no plugging. Air-in leakage through hopper access doors, hopper flanges, and the airlock devices are the primary causes of hopper plugging.
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