Investigation of a novel jet deflector to avoid slag accumulation around secondary air jets in incinerators and boilers

• Published in: Environmental progress 2002-10, Vol.21 (3), p.183-195
• Main Authors: Reynolds, G. K., Goh, Yoke R., Sharifi, V. Nasserzadeh, Swithenbank, Jim
• Format: Article
• Language: English
• Subjects: Accumulation; Applied sciences; Boilers; Burners; Combustion; Computational fluid dynamics; Deflectors; Dynamics; Economics; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fluid flow; Furnaces. Firing chambers. Burners; Hazardous wastes; Incinerators; Inlets; Jets; Optimization; Plants; Slags; Solid and pulverized fuel burners and combustion chambers; Turbulence; Turbulent flow; Waste management
• ISSN: 0278-4491; 1944-7442; 1547-5921; 1944-7450
• DOI: 10.1002/ep.670210316

A major problem in the operation of incinerators is the build‐up of slag on the walls in the throat region of the plant between the furnace chamber and the radiation shaft. This slag can accumulate to a thickness of about one meter, with a weight of several tonnes. This accumulation reduces the availability of the plant, and poses a safety problem, since injury can occur when the material is removed by pneumatic drills during maintenance operations. The excessive downtime, labor, and other economic costs of the slag removal can be minimized by developing a novel, no‐moving‐part jet deflector that can prevent or minimize the accumulation of slag around the jets. The jet deflector was developed and designed by understanding the fundamental principles of the fluid and particle dynamics around the high‐speed jet. Two small‐scale laboratory rigs were constructed for this study. The first rig was a wind tunnel specially designed to minimize the turbulent intensity at the main flow inlet. The second was a combustion rig fitted with an ash/burner injection system, a mobile phone networked particle monitor, and a removable refractory panel onto which the jet and deflector were fitted. An extensive series of laboratory experiments were carried out on both rigs. In parallel with the laboratory investigation, computational fluid dynamic (CFD) analysis of the flow field around the jet and deflector under the same experimental conditions were also conducted. Optimization work on the deflector design was also carried out. Fully optimized jet deflectors were then manufactured and tested in a UK municipal waste incinerator plant. Visual inspections of the jets before and after the deflectors were fitted showed a very significant reduction in the slag formation.