Ashford Clinical Incinerator: Difference between revisions

The Ashford plant [[Incineration|incinerates]] [[Clinical Waste|clinical waste]], including [[Clinical Waste|clinical wastes]] classed as [[Hazardous Waste|hazardous]] under the [[Hazardous Waste (England and Wales) Regulations 2005]]. The bulk of the [[Clinical Waste|waste]] is produced at hospitals, but also includes smaller quantities from doctors’ surgeries, dentists, health clinics, residential and nursing homes, and from medical research facilities. The [[Hazardous Waste|hazardous wastes]] [[Incineration|incinerated]] include infectious waste and waste containing cytotoxic or cytostatic medicines. The plant also [[Incineration|incinerates]] small amounts of specialised wastes where it is recognised that [[High Temperature and Clinical Waste Incineration|high temperature incineration]] represents the best [[Disposal|disposal]] option.

The [[Incineration|Incinerator]] is designed to process 1000 kilograms per hour. The [[Incineration|incinerator]] is of stepped hearth design, with three main [[Combustion|combustion]] hearths and an ash box. [[Healthcare Waste|Healthcare Wastes]] are loaded mechanically direct from the wheeled bins used to deliver the [[Clinical Waste|waste]].

The [[Clinical Waste|waste]] is charged onto the first hearth where the [[Combustion|combustion]] process commences. Hydraulic rams operate at intervals to push the [[Clinical Waste|waste]] along the first hearth, until it falls off the end onto the second hearth where it burns vigorously at a temperature of between 850°C and 1000°C, where it burns out to produce an ash. This bottom ash and any remaining part-combusted [[Clinical Waste|waste]] is then pushed along the hearths, where the fixed carbon in the ash is further burned out. The residues are then dropped into an ash pit the end of the process.

The [[flue gases]] from the [[Incineration|incineration]] process are passed through a secondary chamber, or afterburner, where any gaseous products of [[Combustion|combustion]] are burned out under oxygen rich conditions. This stage is designed to destroy any [[Wikipedia:Carbon monoxide|carbon monoxide]], [[Wikipedia:Volatile organic compound|volatile organic compounds]], and [[Wikipedia:Dioxins and dioxin-like compounds|dioxins]] and [[Wikipedia:Furan|furans]] produced by the [[Combustion|combustion process]].

The [[flue gases]] are then cooled by directing them through a waste-heat boiler before they pass into the abatement section of the process. Powdered [[Wikipedia:Lime (material)|lime]] and powdered [[Wikipedia:Activated carbon|activated carbon]] are added to the [[flue gases]] entering the abatement process to remove acid gases, [[Wikipedia:Heavy metals|heavy metals]] and residual [[Wikipedia:Dioxins and dioxin-like compounds|dioxins]] and [[Wikipedia:Furan|furans]] before discharge to atmosphere from the stack. The [[flue gases]] being discharged from the stack are continuously monitored.

The [[Incineration|incineration]] process produces two residues; [[bottom ash]] and spent lime.