Abstract

We examined pilot-scale bioethanol production from rice straw using sodium carbonate pulping as the alkaline pulping method and enzymatic saccharification. The yield of prewashed rice straw after the crushing and prewashing stage decreased with an increase in the input in rice straw. The pulp yield after alkaline cooking was 66–68% at kappa number ranging from 32 to 36, which was comparatively higher than the laboratory-scale study. The yield of enzymatic saccharized glucose was decreased with the increase in washed pulp and its saccharification rate was approximately 20%. We successfully produced approximately 100 liters of 95% ethanol from 1000 Bone-Dry kg (BDkg) rice straw. The results of our pilot-scale study indicated that the relationship between resource input and product yield for each operation exhibited exponential or logarithmic curves, rather than linear decreases or increases, which could suggest a high-cost structure for bioethanol production when the resource input is larger. However, we established an optimum quantity of resource input, approximately 2000–3000 BDkg in our pilot-scale study, for higher efficiencies.

Abstract

Gas injections at the bottom of the blast furnace create void regions in the coke matrix called the raceways which play a role in the gas distribution in the furnace and is directly linked to the iron production. In this region, complex physical phenomena occur, including particle-fluid with combustion, and, to our knowledge, there is no consensus on its shape and dynamics as well as its creation and stability. A better understanding of the raceway region could lead to a more efficient and stable blast furnace process. An unresolved CFD-DEM approach is used to study the gas-solid flows where coke particles are modelled as a discrete phase and the gas as continuous solving the RANS modelling of the turbulence. In order to clarify the main phenomena occurring in the raceway dynamics, we develop a CFD-DEM model of a 1/5 scale 2d slot pilot of the blast furnace for which alternative raceway collapses are monitored. First, DEM simulations are realized without the fluid contribution and shows that the pilot geometry influences the mechanical load applied on the raceway with a saturation of the granular stress inside the pilot. Also, dry raceway collapse shows a modification of this stress in a short characteristic time. Then, CFD-DEM model of the pilot permits to investigate the gas and granular flows when the raceway is imposed as in the experiment. The dynamics of the collapse with the coupling is solved and displays a complex particle-gas 3d flow. Further implementation in the model will allow coke particle combustion.