Fly Ash Handling
Wherever products are burned it is necessary to have an energy efficient ash handling system, especially in a power station environment where large quantities of pulverized fuel ash (PFA) are created. Such ash can be a considerable environmental nuisance as well as being awkward to handle due to its abrasiveness and hydroscopic characteristics. With the growing environmental awareness that hydraulic ash removal systems are costly in the use of water and land, emphasis has been placed on finding an environmentally safe system.
The unique and comprehensive range of products and technologies from Schenck Process for the Power industry include several innovative methods to handle Ash products to increase the operating efficiency of the power generation process. Utilising a range of technologies from Mechanical Chain and Belt conveyors to Pneumatic conveying with Dense Phase technology, Schenck Process has a proven solution available regardless of plant size.
For installations with a relatively low volume of fly ash or short transit distances Mechanical Conveying is an ideal solution. Where the through put volume of ash is large or the transit distances are long Pneumatic Conveying is more suitable.
Pneumatic Conveying Systems
The Schenck Process pneumatic conveying method of ash handling is clean, efficient and fully enclosed, with exceptional reliability and requiring minimum maintenance. Pneumatic operation of the system saves costs, increases productivity and improves environmental conditions.
The unique Dense Phase technology from Schenck Process is specific to the needs of the power industry and demonstrates worldwide proficiency in safety and economically handling high volumes of ash generated by energy plants.
In operation, ash collects in the precipitator above the Dense Phase vessel. At the appropriate level, the Dome Valve®, situated at the top of the vessel, automatically opens, accepts the ash, and closes. The inflatable seal of the valve provides a positive barrier against the pneumatic conveying pressure.
At high material to air ratios and at a conveying velocity of below 8 m/sec, with a fully automatic operation of the system ensures the precipitator hoppers remain in an empty condition preventing traditional caking and bridging issues.
The main benefits of the Schenck Process pneumatic conveying systems are:
Dens Phase Methodology
Dense phase pneumatic conveying systems operate with higher material:air ratios typically >10:1 giving greater conveying efficiency, capable of handling a wide range of ash, from Coarse to fine.
Every system incorporates the original Dome Valve at the critical point of any pneumatic handling system; the material to air interface, which can operate up to 1,000,000 cycles between scheduled maintenance
Totally enclosed conveying system and pipework greatly reduces the impact on the environment
Low Conveying Velocity
Low conveying velocity typically less than 10 m/sec which minimises the wear on critical components such as conveying pipe and bends
Standard steel conveying pipe
Readily available standard steel pipes are used for the conveying pipelines with no special manufacturer requirements
Low pressure compressed air requirements
Uses medium to low pressure conveying air, typically around 2 – 4 bar(g) generated from standard compressed air plant or blowers provide energy efficient use of absorbed power
Mechanical Conveying Systems
For the Mechanical Conveying of Fly Ash Schenck Process has considerable expertise and experience in the Power sector with the Fairfield En Masse chain conveying system. This system offers a robust and simple solution that does not require a high level of operator or maintenance skill. The Fairfield En Masse principle of conveying is now firmly established worldwide for the mechanical handling of pulverized fuel ash (PFA).
The Benefits of the Stock Fairfield System
- Capital Costs prove very competitive with hydraulic or pneumatic systems.
- The power running costs are significantly lower than most other forms of equipment.
- Heavy duty rigid construction in simple modules, high strength chain, choke detectors, overload and underspeed switches all ensure easy maintenance.
Machines, transfer points, joints and slides are of dust-tight and weatherproof construction.
The totally enclosed construction minimises the ingress of air into a negative pressure system and the escape of gases from a positive pressure system.
The system is free of complicated electronic controls with the mechanical components making it easily maintainable.
The STOCK Fairfield system has the ability to maintain a continuous discharge form the precipitator hoppers.
The system has the ability to discharge precipitator hoppers, which have an accumulated load of ash. The machine capacity can be arranged to clear the accumulated ash over a period of time in addition to the normal drop-out loading.
The system is of robust durable construction. The En-Masse principle of a slow moving chain offers absolute minimum degradation and separation and minimises wear to both casing and chain.
Does not require a high level of operator maintenance skill.
The system is by nature robust and therefore more able to cope with foreign bodies welding rods, gasket material etc. or lumps of ash which may find their way into the system.