The calculation procedure described herein provides a relatively simple, standardized method for rating thermal performance of recovery units. The procedure uses an overall energy and mass balance to establish the thermal conversion efficiency--the amount of steam produced relative to the energy expended. It is designed for use only when the main fuel is black liquor from sodium based pulping operations. The following sections address the possible applications, the data required for the calculations, and the calculation procedure itself.

Forms--in both SI and English units - are provided to systemize data acquisition and to carry out the necessary calculations. The calculation is designed as a computer spreadsheet calculation (compatible with Excel 2002 or later), and is available from TAPPI PRESS.