Macawber Beekay’s product profile includes Jet Pumping System for intermittent removal of bottom ash collected at furnace bottom of PF type boilers. System comprises of water impounded refractory lined Bottom Ash Hopper (BAH) of adequate capacity with water seal trough and dip plates, allowing free expansion of the furnace without any air ingress. BAH is of structural steel, complete with hydraulically operated feed gates, refractory lining along with its cooling arrangement, hopper overflow, water seal boxes, sluicing headers with nozzles, seal trough overflow connection, access doors, inspections glass windows, poke holes and supporting steel structuring platforms, stairs and accessories. Continuous water make-up and overflow system keeps the temperature less than 60DegC in the BAH. Intermittently, de-ashing is done through operation of the inclined hydraulically operated feed gates, clinker crushers and jet pumps. High pressure water supplied to Jet Pumps act as motive water to pump the bottom ash slurry to dewatering bins/slurry sump for further disposal.
For projects demanding continuous removal of bottom ash collected at furnace bottom, Macawber Beekay offers Submerged Scraper Chain Conveyor (SSCC) System. The system comprises of dry type Bottom Ash Hopper (BAH) of adequate capacity with water seal trough and dip plates, allowing free expansion of the furnace without any air ingress. BAH is of steel structure, complete with hydro- pneumatically operated hopper isolation gates, refractory lining along with its cooling arrangement, seal trough with overflow connections, access doors, inspections glass windows, poke holes, quenching nozzles and supporting steel structures platforms, stairs and other accessories.
BAH protects the SSCC from the direct impact of hot ash which is smoothly gravitated to the water bath of the SSCC through horizontal gates provided at discharge of BAH. The discharge chute at the hopper outlet remains dipped into water slag bath of SSCC ensuring sealing of furnace bottom. Storage capacity of BAH permits sufficient maintenance time for SSCC as well as reduces the extraction load on SSCC. Within SSCC, a temperature of less than 60DegC is always maintained by continuous water make-up and overflow system. Bottom ash is extracted from the trough continuously using high quality chains, sprockets and bars. After the dewatering at the sloping portion, moist ash is discharged to clinker crusher for onward disposal either through hydraulic sluice way to slurry pond or through belt conveyors to bottom ash storage silo for onward disposal. For higher capacity SSCC hydraulic drive units, hydraulic chain tensioning units and motorized traverse drives are provided. A standby SSCC should be installed adjacent to the working SSCC. The standby SSCC is not connected to the boiler and is brought under boiler when working SSCC is to be taken out for maintenance etc. The SSCCs are provided with racks, wheels and motorized propulsions arrangement to facilitate removal from under the boiler and its replacement with standby SSCC. Macawber Beekay’s SSCC systems are designed for plant capacity upto 1000 MW.
In certain applications which call for bottom ash available in slurry form to be disposed-off either through trucks or through high concentration slurry disposal system along with fly ash, Macawber Beekay’s De-watering Bin System takes precedence. De-watering bins with the decanting system remove water from the bottom ash and this water can be recycled through a set of settling tanks, surge tanks, transfer pumps, etc. The bottom ash collected in the bin can be either periodically removed through trucks or fed to high concentration slurry disposal system for disposal in paste form along with fly ash, as per plant’s requirement.
Dry Bottom Ash Handling (DRYCON) System is a world-class product added to our product portfolio in view of the environmental concerns of conserving water. Regardless of the quality, quantity and utility of bottom ash, it is absolutely advantageous to adopt a DRYCON system for Bottom Ash extraction.
The DRYCON system is mounted fully sealed to the combustion chamber. The negative pressure inside the boiler sucks air in a controlled manner mainly at the top end of the DRYCON system into the DRYCON system. This air travels in counter flow direction along the surface of the ash, which rests on the conveyor belt. This activates a re-burning process of the glowing ash, which reduces the unburned carbon level and frees up additional thermal energy. The air is heated up before it enters the combustion chamber and adds additional thermal energy to the steam generating process inside the boiler.
Certain applications which specially require Mechanical System, like in case of CFBC / AFBC type boilers for handling of bed ash collected at furnace bed, Macawber Beekay offers drag chain conveyor system, followed by pressure pneumatic conveying system as per the Client's specific requirement. The chain conveyor collects cooled bed ash, which is taken out of boiler area and fed to a surge hopper for further transport to the bed ash silo through our dense phase pneumatic system.
This way bed ash silo(s) can be placed at a convenient distant location within the plant. Material pipes travel overhead leaning plant movement unrestricted.
Macawber Beekay specializes in Dense Phase Pneumatic Conveying System for handling of bed ash collected at furnace bed of AFBC / CFBC boilers firing various fuels like coal, lignite, char coal, etc.
Macawber Beekay, with its unique Dome Valve design and the technology of Dense Phase Pneumatic Conveying, has always kept a brand name for such abrasive applications by giving practical solutions to various requirements as arise from time to time, irrespective of batch type/continuous conveying, shorter/longer distances, lower/higher capacities, temperature ranges, etc. MBPL's Pressure Pneumatic Conveying Systems installation capacity range require no mention.
The pneumatic bed ash handling system, in general, consists of collection of bed ash from BA coolers (supplied by others) in water cooled surge hoppers. A suitable sized grizzly is provided to separate any lump, which is collected in by-pass chute and removed manually. Below surge hopper, a Denseveyor is provided to pneumatically convey bed ash from boiler area to BA Silo, installed at a convenient location in the Plant. Denseveyor is equipped with pneumatic actuated Dome Valve and a manually operated isolations maintenance plate valve at its top. Special designed material conveying pipes are used to handle this material.
On top of BA Silo, vent filter is provided to clean the venting air. BA Silo and water cooled surge hopper are equipped with local sensors to monitor and control the material levels.
BA Silo is equipped with dry and / or wet unloading system for disposal of bed ash through trucks.