Recovery BLOX System Overview and Principles

Some recovery boilers use waste heat from the combustion gases to evaporate water from incoming black liquor. This increases the efficiency in the amount of steam produced by the boiler. In direct contact evaporators, hot combustion gases directly contact black liquor. This concentrates the black liquor using waste heat, but it also adds unwanted emissions of malodorous sulfur gases to the flue gas. The black liquor oxidation (BLOX) system is designed to pre-treat the black liquor to minimize these emissions. This module covers direct contact evaporators and the theory and operation of the BLOX system.

•Define the term TRS •Define the term BLOX •Explain where TRS comes from •Identify and describe a cascade direct contact evaporator •Identify and describe a cyclone direct contact evaporator •Describe where direct contact evaporators fit into the kraft recovery process •Explain the principle behind a black liquor oxidizer •Describe where black liquor oxidizers fit into the kraft recovery process