Fuel Storage and Handling for Boilers
A boiler can only run as well as its fuel arrives. For solid fuels, the yard, the conveyors and the bunker are as much a part of the steam plant as the boiler itself, and most unplanned stops in a solid-fuel boiler house start in the fuel system.
You'll learn
- Describe a solid-fuel handling chain from yard to furnace
- Keep fuel dry and avoid spontaneous combustion
- Know the storage needs of oil and gas
- Recognize the faults that stop a boiler from the fuel side
Before this: Coal and lignite, Biomass fuels, moisture and ash
From the yard to the furnace
- Receipt and storage: trucks unload into a yard or shed. Fuel is weighed and, ideally, sampled for moisture and GCV.
- Preparation: coal is crushed and screened to the size the grate or bed needs; biomass may be screened to remove oversize and stones.
- Conveying: belt, screw, chain or bucket conveyors lift the fuel to the boiler house.
- Bunkering: a bunker or day hopper above the boiler holds a few hours’ supply.
- Feeding: a feeder meters fuel into the furnace at the rate the load needs.
Each step has to match the boiler’s fuel consumption at full load with a margin, and each can stop the boiler if it fails. That is why critical conveyors are often duplicated and why the day bunker is sized to ride out a conveyor breakdown.
Storing solid fuel well
- Keep it dry: covered storage protects heat value and stops wet fuel bridging in bunkers and choking feeders. Every point of moisture is fuel paid for and not burned.
- First in, first out: old stock degrades and, for coal, heats up.
- Separate grades and fuels: mixing in the yard makes boiler behavior unpredictable.
- Control dust: fines and dust are a fire and explosion risk around conveyors and transfer points, and an emission problem in the yard.
Coal stockpiles can heat by slow oxidation and eventually catch fire on their own: spontaneous combustion. Risk rises with fine, high-volatile coal, loose piles that let air in, and long storage. Compacted, well-shaped piles of limited height, regular temperature checks, and using older stock first keep it in hand. Damp biomass piles can also self-heat through biological activity.
Liquid and gas fuels, and fuel-side failures
Oil storage needs bunded tanks that can contain a spill, heating for furnace oil, water draining from the tank bottom, and filters before the pumps. The quantities and layout of petroleum storage are regulated under the Petroleum Rules, administered by PESO. Gas installations need a pressure-regulating station, leak-tight piping, isolation valves outside the boiler house, ventilation, and gas detection appropriate to whether the gas is lighter (natural gas) or heavier (LPG) than air.
- Bridging and rat-holing: wet or stringy fuel arches over a hopper outlet and the feeder runs empty. Hopper geometry, vibrators and dry fuel prevent it.
- Tramp material: stones, metal and wire jam crushers and feeders and damage grates. Magnetic separators and screens catch them.
- Inconsistent size: fines blow through unburnt, oversize does not burn out. Crushing and screening to the boiler’s specification matters as much as the GCV.
- Conveyor fires and dust explosions: housekeeping, spillage control and dust extraction around transfer points.
Key takeaways
- Yard → preparation → conveying → bunker → feeder: each must match full-load fuel use.
- Keep solid fuel dry, first in first out, and separated by grade.
- Coal and damp biomass piles can self-heat; manage pile shape, height and age.
- Oil needs bunded, heated, drained storage; gas needs regulation, isolation and leak detection.