Application of a Pseudo-Kinetic Generalized Serverity Model to the Concentrated Sulfuric Acid Hydrolysis of Pinewood and Aspenwood

The yield of monosaccharides after two-stage concentrated sulfuric acid hydrolysis of softwood (Scots pine) and hardwood (trembling aspen) was modeled using a generalized severity parameter with a time-independent rate constant. The severity parameter, which combines the major operating variables acid concentration, temperature, and reaction time in the decrystallization stage into a single reaction ordinate, was successfully used to describe monosaccharide yields after a standardized hydrolysis stage. Conversion of cellulose to glucose demanded a higher severity to reach maximum glucose yields than the conversion of hemicelluloses to their respective monosaccharides, and the conversion of pine demanded a higher severity to obtain maximum monosaccharide yields as compared to aspen. The results indicate that the generalized severity parameter can be a useful tool for the prediction of sugar yields in a two-stage concentrated sulfuric acid hydrolysis process

APPLICATION OF A PSEUDO-KINETIC GENERALIZED SEVERITY MODEL TO THE CONCENTRATED SULFURIC ACID HYDROLYSIS OF PINEWOOD AND ASPENWOOD

The yield of monosaccharides after two-stage concentrated sulfuric acid hydrolysis of softwood (Scots pine) and hardwood (trembling aspen) was modeled using a generalized severity parameter with a time-independent rate constant. The severity parameter, which combines the major operating variables acid concentration, temperature, and reaction time in the decrystallization stage into a single reaction ordinate, was successfully used to describe monosaccharide yields after a standardized hydrolysis stage. Conversion of cellulose to glucose demanded a higher severity to reach maximum glucose yields than the conversion of hemicelluloses to their respective monosaccharides, and the conversion of pine demanded a higher severity to obtain maximum monosaccharide yields as compared to aspen. The results indicate that the generalized severity parameter can be a useful tool for the prediction of sugar yields in a two-stage concentrated sulfuric acid hydrolysis process

Saccharification of Lignocellulosic Biomass for Biofuel and Biorefinery Applications – A Renaissance for the Concentrated Acid Hydrolysis?

AbstractHydrolysis of lignocelluloses using concentrated acids achieves near-theoretical sugar yields, and with fewer degradation products than the more commonly employed dilute acid hydrolysis process. In this paper, the dependence of sugar yield and the production of fermentation inhibitors on central process parameters is investigated, and the “severity factor” concept of one single process parameter characterizing the extent of the reaction is applied for the first time to concentrated acid hydrolysis of lignocellulosic biomass. Selected hydrolyzates have been fermented in the laboratory to investigate the effect of analyzed and unknown fermentation inhibitors in the hydrolyzates on fermentation performance. The concentrated acid hydrolysis process appears to be an interesting process for saccharification of lignocellulosic biomass for biofuel and biorefinery applications, with high sugar yields, low levels of fermentation inhibitors, good fermentability and good robustness towards changes in raw material quality

Improved heuristic algorithm for selection of tear streams and precedence ordering in process flowsheeting computations

This paper presents a new algorithm based on the heuristic tearing algorithm by Gundersen and Hertzberg (1983). The basic idea in both the original and the proposed algorithm is sequential tearing of strong components which have been identified by an algorithm proposed by Targan (1972). The new algorithm has two alternative options for selection of tear streams, and alternative precedence orderings may be generated for the selected set of tear streams. The algorithm has been tested on several problems. It has identified minimal (optimal) tear sets for all of them, including the four problems presented in Gundersen and Hertzberg (1983) where the original algorithm could not find a minimal tear set. A Lisp implementation of the algorithm is described, and example problems arc presented