Experiences of Bagasse Black Liquor Evaporation, 1998 North America Nonwood Fiber Symposium Proceedings

This paper discusses special properties of bagasse black liquors and the influence of these properties on evaporation system design and performance. The physical properties of these liquors are compared with wood-based black liquors referencing available literature and our own laboratory measurements.

The influence of thermal heat treatment on the viscosity behaviour of bagasse liquor is described and its potential to improve the evaporation and combustion economy of a bagasse mill is discussed.

The pilot test results of evaporating bagasse black liquor are presented. The test trials were performed in India using an Ahlstrom free-flow falling film plate type evaporator. It seems that with modern evaporator design, the operation range of 60 - 65 % dry solids level is achievable with normal indirect heating surfaces. If the liquor is heat-treated it is possible to reach 70 % dry solids, based upon laboratory results.

The combustion characteristics of a bagasse black liquor are described and the influence of higher dry solids on the boiler design and operation are discussed.