Allen-Sherman-Hoff Submerged Chain Conveyor (SGC)
Submerged Grind Conveyor (SGC) System

Simplified, flexible design for effective bottom ash transport and dewatering

Patented, proven technology simplifies installation and operation for superior ash handling

The challenge to effectively and reliably meet regulatory targets for bottom ash handling has often required plant operators to make significant investments in equipment modifications.

Babcock & Wilcox Environmental set out to develop a new conveyance technology that not only met effluent limitation guidelines (ELG) and coal combustion residuals (CCR) requirements, but also considered unique plant layouts in providing a simplified and more cost-effective solution. The result? B&W has developed, patented and proven its Allen-Sherman-Hoff® Submerged Grind Conveyor (SGC) system, which offers maximized results and minimized modifications to the existing footprint.

B&W’s new submerged grind conveyor offers a simplified and cost-effective system that meets zero-discharge bottom ash removal requirements with consideration to each unique plant layout.

B&W Submerged Chain Conveyor (SGC)

Compact and flexible, our SGC
collects the bottom ash from the
discharge of each clinker grinder
and transports it using a series of
bottom-carry, submerged drag
chain conveyors.

No ash transport water is used, which meets the ELG requirement for closed loop or zero discharge of water. And it’s designed around your equipment, reducing conversion costs by retaining existing ash hoppers and boiler seal plates.

Our SGC system offers flexibility in design to avoid disruption to operations and shorten installation time and costs. Conveyors can be oriented at angles and with turns around existing equipment that would otherwise be expensive to relocate.

Both the bottom carry chain and flights and the return chain and flights
are contained in a small cross-section, water-tight enclosure. The hopper
remains water-impounded to quench the bottom ash and support a water
seal at the bottom end of the furnace for optimal fuel efficiency and emissions control.

Conventional submerged conveyors
require a straight path to a location
outside the boiler building. Our SGC
does not.
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  • Utilizes existing bottom ash hoppers or slag tanks for bottom ash collection
  • Isolation from the hoppers for safe online maintenance
  • Utilizes existing bottom ash gate, clinker grinders and transfer enclosure (dog house) between gate and grinders
  • Conveyors can be oriented at angles to avoid existing structures and equipment, eliminating the requirement for straight pathway to a location outside boiler building as with traditional conveyors
  • Smaller and lighter than conventional submerged chain conveyors because it receives bottom ash after crushing by clinker grinders and is not subject to heavy loads from slag falls or weight of bottom ash stored during maintenance
  • Smaller, flexible design can be adapted between boiler and outside boiler house en route to storage bunker, avoiding moves and demolition

B&W’s SGC has been researched, developed and proven at our test facility in Lancaster, Ohio.


  • Reuse of existing water-sluice system’s key components reduces installation costs for retrofit
  • Reuse of existing bottom hoppers protects conveyor from impact of slag falls
  • Capability for redundancy, allowing for uninterrupted power if one chain conveyor string is out of service
  • Minimized outage time
  • Low profile, small footprint
  • Improved fuel efficiency and emissions control from water-filled ash collection hopper and supported water seal, which is designed to optimize O2 levels and minimize NOx
  • Low-wear, compact mechanical conveyor system reduces material costs
  • Low auxiliary power requirements
  • Low maintenance costs

B&W Submerged Grind Conveyor
System designed to convey dewatered bottom ash from hopper through a series of compact SGCs for discharge into storage bunker


B&W Environmental's Submerged Grind Conveyor expert discusses the problem-solving ingenuity behind the SGC design, including a success story in which the installation reduced ongoing costs of the plant's high-pressure sluice system.

Designed for Flexible Installation and Ease of Operation

Going above and beyond by going below and around 

Every aspect of the submerged grind conveyor (SGC) design took into account the impact of a retrofit from its initial installation through its ongoing operation.

Because our SGC is small and compact — and doesn’t require the removal or displacement of bottom ash hoppers or slag tanks, ash gates, clinker grinders, transfer enclosures and other existing equipment — installation can be accelerated to save time at a lower cost than other bottom ash conveyance systems. In addition, the simpler, mechanical transfer conveyor design has low auxiliary power requirements and low maintenance costs.
All of these benefits come with the high performance, predictable results and trusted reliability you have come to expect from B&W and the Allen-Sherman-Hoff line of material handling solutions.
To ease maintenance over time and use of the conveyor, the existing ash gate was designed to isolate the conveyor from the ash hopper. The boiler can stay online since ash can be stored in the existing ash hopper, and the conveyors are equipped with variable speed drives to make up for any resulting slowdown. 
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New Build

B&W Projects New Build
We consistently demonstrate the ability to successfully execute innovative solutions for our customers, from new equipment to large, complex full-scope engineering and construction projects.

Upgrades / Retrofits

Upgrades and Retrofits by B&W
Modifying, improving and maintaining existing equipment are vital considerations for the long-term viability and profitability of all operations.

Parts / Services

Babcock & Wilcox Parts and Service Support
An extensive network of worldwide regional service centers, field service engineers and technical support personnel are available to provide the customized service and aftermarket solutions for your requirements.