Computer simulation and economic analysis for ammonia fiber explosion (AFEX) pretreatment process

Abstract

The ammonia fiber explosion (AFFECT) process is a promising new pretreatment for enhancing the reactivity of lignocerulose materials with many advantages over existing processes. The material is soaked in high-pressure liquid ammonia for a few minutes then the pressure is explosively released. A combined chemical (cellulose decrystamution) and physical (increased surface area) effect increases the enzymatic digestibility of lignocelmose. The laboratory phase of AFEX development is nearing completion, and a brief preliminary economic analysis (without detailed sizing) was finished. However, a commercial size plant has not been developed. This study was undertaken in an effort to support and assist AFEX commercialization through process simulation and cost analysis. In this study, a steady state computer simulation package was developed for the AFEX process. Corn fiber was used as the representative biomass treated by AFEX. Different ammonia loadings, water loadings, temperatures and pressures were used as operational parameters. Mass balances and energy balances are the major determinants of the equipments selected and sized. 'nermodynamic models or kinetic models are also included. A preliminary cost estimate includes total purchased-equipment cost using the equipment cost ratio method. The process computer simulation model was programmed in FORTRAN. FORTRAN subroutine libraries from IMSL (International Mathematical and Statistics Library), Inc. were used as needed. To increase the portability of the program, the programming was done on an EBM compatible PC.