| OCR Text |
Show 5.6.2 non-slagging types, depending on the behaviour of any ash present. Slagging combustors tend to possess a single tangential air inlet and are termed cyclone combustors, whilst the non-slagging types have at least two air inlets and are then termed vortex combustors. The early water model, of a specific incinerator, used polystyrene beads and nigrosine dye to visualise the air and fuel flows, and clearly illustrated the complex but stable nature of the double helix, vortex flow. In practical terms, this means that noxious residues can be completely burnt off within the chamber and that the unit is only about 20% of the size of a conventional incinerator, for the same duty. A later, and much more useful, air model test bench was then set up to produce velocity profiles using automated impact head probe devices. This study indicates that the best practical design of such an incinerator is a non-slagging, axially fired, vortex combustor with dual tangential inlets for the secondary air supply. 1.0 Introduction The rapid technological changes, occurring since World War II have created a situation where environmental pollution problems can no longer be solved easily, either by dumping untreated effluents in holes or rivers, or by discharging harmful gases and dusts into the atmosphere. Increasingly effective legislation has obliged industry to dispose of its noxious and toxic waste products in a more scientific and less objectionable way. Waste disposal can be carried out by any of the following methods, depending on the nature of the pollutant and its byproducts. (i) Dumping and covering, which allows natural bacterial decay to decompose some of the waste. (ii) Incineration, producing relatively harmless gases which are then released to atmosphere. (iii) Microbiological degradation, using specific bacteria to slowly decompose the waste to harmless, or perhaps even useful, end products. (iv) Chemical neutralisation, using specific compounds which render the waste product innocuous. (v) Containerisation and storage, usually under strict security, to ensure |
