Gross heating value of black liquor

This method determines the gross (or high) heating value of black liquor, containing up to 55% by mass of water, derived from sodium-based kraft pulping1.

The products of combustion in the recovery furnace are different from the bomb calorimeter products because of the reducing atmosphere which exists in the hearth zone of the furnace. A “heat of reaction correction” based on an elemental analysis of the waste liquor sample should be used to account for this difference. It is described in a TAPPI Steam and Power Committee Technical Information Sheet for calculation of recovery unit performance (TIP 0416-01 “Recovery Boiler Performance Calculation - Short Form”).