Inorganic Chemistry during Pyrolysis, Gasification, and Oxyfuel Combustion of Kraft Pulping Black Liquor

Abstract

Changed utilization of black liquor in the pulp and paper industry has the potential to offer simplified carbon capture and, thus, negative net emissions from these large point sources. This can be achieved either by adapting existing recovery boilers to oxyfuel combustion or by replacing them with black liquor gasification technology. In this work, the chemistry during black liquor conversion was therefore studied in detail under different atmospheres relevant for pyrolysis, gasification, and oxyfuel combustion. Experiments were performed using environmental scanning transmission electron microscopy (ESTEM) and thermogravimetric analysis (TGA), supported with thermodynamic equilibrium calculations (TECs) to understand and interpret the results. Black liquor conversion was found to be generally similar in air and oxyfuel atmospheres containing approximately 20−25 mol % oxygen. The results however indicated that there was a higher probability of forming carbonates in the melt at higher carbon dioxide (CO 2 ) partial pressures, which in addition was found to be associated with potentially higher sulfur loss during black liquor conversion. Both of these characteristics can negatively affect the chemical recycling at the pulp mill by increasing the need for lime and makeup chemicals.

Involvement of Acid-Leachable Inorganics in Pyrolysis of Pig Manure

“…Pig manure, in fact, is a carbonaceous resource, containing chemical energy that could be further exploited via a thermochemical route, like pyrolysis. , Pyrolysis is a process for converting carbonaceous materials, like pig manure, into char, bio-oil, and combustible gases. , Char could be used for soil amendment and the preparation of a carbon-based catalyst and as adsorbent or electrode material for energy storage. , Bio-oil is seen as a potential feedstock for the production of biofuel. , Gases from pyrolysis could be combusted for providing heat required for pyrolysis. , As a waste in livestock production, pig manure production is relatively stable and has no seasonal fluctuations . If fully utilized, it can not only reduce environmental pollution but also generate an added value. , …”