Ash Handling System

About Ash Handling System

Every solid-fuel boiler produces ash, and an ash handling system removes it continuously so the boiler never has to stop to be raked out. There are two streams: bottom ash and clinker that fall from the grate or bed, and fly ash carried out with the flue gas and collected in the economizer, air heater and dust collector hoppers.

Bottom ash is handled dry or wet. Dry systems use screw or drag chain conveyors to carry cooled ash away; wet systems use a submerged chain conveyor that quenches hot ash in a water trough and drags it out dewatered. Fly ash is usually conveyed dry — by screw, drag chain or pneumatic conveying — to an ash silo, from which it is unloaded into trucks.

Ash from biomass and rice husk is fine, light and highly abrasive, and ash from high-ash coal arrives in large quantities. Both shape the design: wear-resistant conveyor parts, rotary airlocks that hold the hopper seal while discharging, and dust control at every transfer, so that ash leaves the boiler house without spreading through it.

We design and supply ash handling systems with new solid-fuel boilers and for existing plants, covering bottom ash, fly ash, silo storage and unloading.

How much ash a system has to move follows from the fuel rather than from the boiler. High-ash Indian coal leaves a great deal behind; washed or imported coal much less; and biomass varies enormously, from wood chips that leave almost nothing to rice husk, which is roughly a fifth ash by weight. That single figure — ash percentage against fuel consumption — sets the size of every conveyor, hopper and silo in the system, which is why we ask for a fuel analysis rather than a fuel name.

The split between bottom ash and fly ash depends on how the boiler fires. A grate boiler drops most of its ash through the grate as bottom ash and clinker; a fluidized bed boiler carries a much larger share out with the flue gas, to be collected in the economizer, air heater and dust collector hoppers. A system designed for one and installed on the other will have the wrong capacity in both halves.

Fly ash is hot, fine and abrasive, and it flows like a liquid when aerated and sets hard when damp — which is why every part of its route is designed around keeping it moving and keeping air where it belongs. Rotary airlocks hold the hopper seal while discharging, because a hopper that leaks air loses collection efficiency in the equipment above it; ash conditioners wet the ash at the point of discharge so it can be trucked without blowing off the load; and every transfer point is sealed rather than merely covered.

Typical duty is a husk or biomass fired boiler in a rice mill or process plant, and an AFBC or grate-fired coal boiler in a captive power house. We supply ash handling with new boilers and as a retrofit where ash is still being raked out and barrowed away — bottom ash, fly ash, silo and unloading engineered together, with erection, commissioning, wear spares and an AMC where the plant wants one.

Ash Handling System Key Features

• Continuous removal without stopping the boiler
• Dry or wet (submerged) bottom ash handling
• Fly ash collection from economizer, air heater and dust collector hoppers
• Screw, drag chain and pneumatic ash conveying
• Rotary airlocks to hold hopper seals
• Ash silo with unloading for trucks
• Wear-resistant parts for abrasive biomass and husk ash
• Dust control at every transfer point
• Capacity worked out from the fuel’s ash content, not a nominal figure
• Designed to the firing method’s bottom-ash / fly-ash split
• Ash conditioner to damp ash for trucking without dust
• Sealed hoppers and transfer points throughout the route
• Fly ash cooling where discharge temperature requires it
• Silo level indication with high-level alarm
• Standby routes or manual discharge so ash removal never stops the boiler

Ash Handling System Specification

Ash Types Handled

Ash Handling Technology

Ash Handling System Applications

Industries Served

Advantages of an Ash Handling System

Optional Accessories