Wythenshawe Hospital


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ACWA AIR designed, installed and commissioned a new gas cleaning plant for the clinical waste incinerator for Wythenshawe Hospital. ACWA also arranged for the project to be directly financed to allow the South Manchester University Hospital Trust to operate the plant on leasehold.

In addition to cleaning the incinerator gases, the dry scrubbing system will also provide a degree of heat recovery, capable of preheating feed water for the hospital’s steam boilers. This is to be achieved by a heat exchange system in which hot flue gases from the incinerator are ducted through an economiser. As the flue gases are cooled from 450°C to 180°C – by pressurised water passing through horizontal tubes – the temperature of the water increases. This closed circuit pressurised water system is used to heat the boiler feed water in the hotwells.

Cooled gases discharged from the economiser are then injected with sodium bicarbonate, which reacts with the acid gases and powdered activated carbon (PAC) to adsorb contaminants such as dioxins, furans and heavy metals.

In the next stage of the process, flue gases enter a gas filter installed with ceramic elements which filter out particulates and used reactants. Capable of withstanding temperatures in excess of 400°C, the filter elements hang vertically within a strong rigid housing, supported at both ends to provide an extremely robust system. A baffle distribution plate is installed at the filter inlet to ensure an even distribution of gas throughout the filter housing and protect the elements against any large foreign objects present in the gas stream. The rigidity of the filter elements allow uniform distribution of sorbent coating to form on all collection surfaces, enabling high removal efficiencies and sorbent utilisation to be achieved.

The ceramic elements will be cleaned periodically by a reverse pulse of Compressed air, which removes dust to a hopper installed at the base of the Filter. From here it is transferred, via a rotary valve and screw conveyor, into an FIBC for disposal. The cleaned gases will be ducted through an induced draught fan and vented to atmosphere via a chimney stack.

Project Details

Client: Wythenshawe Hospital

Industry: Health Service

Application: Heat recovery and dry scrubbing system to clean flue gases from a clinical waste incinerator.

Technologies

Dry Scrubbing
Dry Scrubbing