As regulations controlling VOC and the environment become increasingly strict at local, national and international level, manufacturers in an increasing range of industries are having to consider appropriate action. The wood industry is no exception.
In the manufacture of moulded wooden doors, for example, wood shavings and sawdust are bonded together with phenol formaldehyde resins. They are then pressed, sprayed with linseed oil and transferred to a kiln where the doors are cured. Airborne contaminants are produced at every stage of this process, amongst them the highly odorous phenol, cresol and formaldehyde, as well as particulate matter.
This is an area in which the environmental control systems provided by Haden have already proved their worth. The challenge was to provide a solution on behalf of a moulded door manufacturer which was being pressed for action to meet tight local authority controls on VOC emissions.
99% OF VOC DESTROYED
The answer was a large regenerative oxidiser, capable of treating 136,000Nm3/hour of exhaust air. Under the new system, all the emissions from every stage of the process are ducted together and brought into the oxidiser by a single feed. Well over 99% of VOC is removed from the air stream and broken down by heat into carbon dioxide and water vapour. Not surprisingly, emissions from the plant have been slashed.
An extra benefit of the system is its low running cost, which is down to the thermal efficiency of the oxidiser - in excess of 95%. High thermal efficiency is one of the hallmarks of regenerative oxidisation, as the process is designed to ensure that nearly all the heat required for VOC destruction is recovered within the oxidiser.
CERAMIC BEDS RECOVER HEAT
Ceramic beds are the key to the heat recovery system. These beds remove heat from the hot clean air leaving the combustion chamber and transfer it to the incoming contaminated air. So efficient is this process that the burners in the combustion chamber only have to raise the temperature of the incoming air a fraction further to reach the final oxidation temperature.
LONG LIFE AND LOW MAINTENANCE
Haden’s system also offers two additional benefits. The design of the valves ensures a long life, minimising maintenance costs, while a smokeless burn-out feature provides for automatic cleaning of the ceramic media. Clogging, plugging and particulate build-up is thus elimated.
A SYSTEM FOR THE FUTURE
In operation, the system has proved a success. The manufacturer has a high performance system with a variety of features to minimise operating costs. It has benefited from better environmental controls, enhancing the standing of the company in its local community.
Indeed, tests have demonstrated that emissions are not only well within current local authority targets, they will comply with foreseeable legislation to come. While costs have been held to a minimum, Haden’s solution is proving to be in every sense a system for the future.