Liquor-To-Liquor Differences in a Combustion and Gasification Processes: Dust Composition and Melting Properties, 1998 International Chemical Recovery Conference Proceedings

This work is a continuation of our advanced liquor characterization studies, in which we have tested a set of different mill liquors, using novel laboratory tests and chemical analyses to gain better predictions of the liquor behavior in combustion or gasification processes. In this paper, we focus on the behavior and properties of the inorganic residues (carryover) and condensed dust (fume) formed during combustion of these liquors.

We present data for eight widely different mill liquor samples from various types of processes. Based on (i) elemental analyses of the liquors, (ii) analyses of the char residues obtained by single-particle pyrolysis tests and (iii) advanced chemical modeling of the formation and conversion of the inorganic material in combustion, we have estimated the composition of the droplet residues (carryover particles) and condensed dust (fume particles) that are formed when the liquors are fired under typical recovery boiler conditions.

The liquors were characterized this way for two sets of recovery furnace conditions, for a “hot furnace” (high solids firing conditions) and for a “cool furnace” (normal solids). The main difference between these two sets of conditions comes from the behavior of sulfur and chlorine at these two conditions.

We also made predictions for the melting behavior of the carryover and fume particles to be formed. The melting range estimates are based on the alkali salt melting equilibrium model recently developed at Åbo Akademi University. The results show that the sticky temperature (T15 ) estimated for the liquors varies between 590 and 740° for the carryover particles and between 540 and 860°C for the fume particles.

For the liquors, we also present data obtained from boilers that fire these liquors. Both ESP dust samples and short term superheater deposit samples were collected from all the boilers. The compositions and melting properties of these samples were compared with the predicted fume and carryover compositions, respectively.