Roles of Black Liquor Compostion and Boiler Combustion Parameters on the Fouling Tendency of Recovery Boiler, 1998 International Chemical Recovery Conference Proceedings

This paper is based on earlier studies of eight recovery boilers. The studies have discussed the fouling tendency of operating recovery boilers, the role of the black liquor composition and boiler design and operational parameters. In this paper we summarize the earlier studies and develop further the use of the enrichment factor concept as a tool for adressing fouling problems.

The boilers have been studied with the same methods using deposition probes in different boiler locations.

We also discuss the factors affecting the composition and melting behaviour of the collected probe samples (corresponding the superheater and boiler bank deposits). The effects of liquor analysis (mostly Cl and K contents) and the operational parameters are discussed.

Enrichment factors are defined for samples collected from different sampling locations in the boilers and the role of furnace heat load, temperature and dust load on the melting temperatures To (first melting temperature), T15 (sticky temper&we), T70 (flow temperature) of the deposits, and on the superheater deposit thickness is discussed.

For the measured boilers, the effects of variations in furnace conditions on the first melting temperature T0 are in the range of 10 - 20°C. The total variation (including the influence of different liquor) is about 40°C. The sticky temperature T15 variation due to the furnace conditions is in the range of l00°C, which is the same order of magnitude as the variation of the measured flue gas temperatures in different boilers. The total sticky temperature variation of the measured boilers is more than 200°C.

The furnace conditions do not affect the flow temperature T70 or the deposit equilibrium thickness of the superheater deposit significantly.