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Abstract:In any combustion process of a fuel there will be always some unburned carbon (soot) generated and some ash carried with the stack gas stream. Soot, ash, and molten ash (slag) will accumulate at the tube banks of the heat exchangers. Some ash will even melt down at the tube surface. The final result is a layer insulating the tubes against the hot combustion gases. Soot emission from combustion devices, industrial process equipment, cause serious problems to the environment and human health. The formation of ash deposits on heat transfer surfaces has been one of the main problems encountered in industrial process equipment. Ash deposits not only lower the heat transfer rates, resulting in frequent maintenance and unscheduled shutdown.In present experimental and simulation study different length horn are used to measure sound pressure level at various distance and at different input air pressure. Then from literature equation is used to predict sound pressure level required to dislodge ash, soot and dust. Prototype is also built for demonstration.

The present work describes the occurrence of thermo-acoustic instability inside a horizontal Rijke tube and its suppression using an open loop active control technique. The Rijke tube is provided with a co-axial pre-mixed gas burner as the source of heat, which could be placed at any desired position. Radial injection of air (less than 3% of the total mass flow) through micro-jets into the flame is used as a control technique to suppress the thermo-acoustic instability. The rise in heat content inside the Rijke tube, estimated from the temperature mapping, clearly shows reduction in the heat loss as a result of complete suppression of the thermo-acoustic instability. However, the stability achieved passively by means of a slight shift in the burner position does not result in any change in the heat content. There is a visible change in the appearance of the burner flame when the above two methods are used to suppress the thermo-acoustic instability. The flame is seen to significantly shrink in length and spread radially when the control technique was applied. The flame dynamics is believed to determine the heat loss and hence the heat content inside the Rijke tube.

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