E.R. Morais

Technical and economic assessment of trash recovery in the sugarcane bioenergy production system

Mechanized sugarcane (Saccharum spp.) harvest without burning has been increasingly adopted in Brazil, increasing trash availability on the field. This study aims at showing the importance of using an integrated framework tool to assess technical and economic impacts of integral harvesting and baling trash recovery strategies and different recovery rates as well as its implications in the sugarcane production, transport and processing stages. Trash recovery using baling system presents higher costs per unit of mass of recovered trash in comparison to system in which trash is harvested and transported with sugarcane stalks (integral harvesting system). However, the integrated agricultural and industrial assessment showed that recovering trash using baling system presents better economic results (higher internal rate of return and lower ethanol production cost) than the integral harvesting system for trash recovery rates higher than 30 %. Varying trash recovery fraction, stalks productivity and mean transport distance for both integral harvesting and baling systems, sensitivity analyses showed that higher trash recovery fractions associated with higher stalks yields and long transport distances favors baling system, mainly due to the reduction of bulk load density for integral harvesting system under those conditions.

Real-time optimization for lactic acid production from sucrose fermentation by Lactobacillus plantarum

Abstract A great obstacle in the lactic acid fermentative process is the inhibition of the growth cell by final product as well as by substrate high concentration. A highly efficient process can be developed from a continuous fermentative process with low feed rate of substrate and continuous removal of product. In this work, an investigation study of the optimization and optimal control of operational parameters of a continuous fermentative process for lactic acid production from sucrose is presented. The general idea is to develop suitable tools for defining the optimal operational condition or the set points in the optimization layer in order to obtain an efficient process for lactic acid production. This is in fact a realt-time optimization procedure that should be able to avoid cell growth inhibition and increasing the final concentration of the product. The results show that it is possible to run the system at the best operating conditions, and a highly efficient process for lactic acid production from the sucrose fermentation can be obtained.

Use of VSB to Plan Research Programs and Public Policies

The VSB comprises a useful framework for assessing research programs, and define and evaluate the effects of public policies. This chapter describes two cases regarding the use of VSB for R&D evaluation—enzyme development and use of energy cane as a new feedstock for sugarcane biorefinery—and a public policy formulation for biogas production and use in the biorefinery context.

Techno-Economic Analysis of Second-Generation Ethanol in Brazil: Competitive, Complementary Aspects with First-Generation Ethanol

Brazil achieved important success in the implementation of ethanol as a reality renewable energy source after the inception of the National Alcohol Program (PROALCOOL) in 1970. Today, ethanol produced from sugarcane replaces almost 50 % of gasoline in Brazil. More than 448 bioethanol production (first-generation ethanol) units are functional, which fulfill the 25 % ethanol blending to gasoline that eventually reduces the import of 550 million oil barrels improving the socioeconomic status and saving foreign exchange reserves. Brazil has more than 80 % of its light vehicles running on bioethanol, reducing greenhouse gas emissions. At present, this demand for ethanol is being met through first-generation (1G) ethanol which is directly produced from sugarcane juice and molasses. However, significant research in bioenergy in the last two decades has shown the possibilities of commercialization of second-generation (2G) ethanol, which can be produced from sugarcane bagasse (SB) and straw (SS), complementing 1G ethanol. Nevertheless, both the residues (SB and SS) are an excellent source for cogeneration of heat and power (CHP) in sugarcane processing units. Process simulation studies have provided additional source of information on the overall use of sugarcane for ethanol production and CHP. For the evaluation of the fullest utilization of sugarcane and its by-products, CTBE (Brazilian Bioethanol Science and Technology Laboratory) has developed the Virtual Sugarcane Biorefinery (VSB), a comprehensive assessment framework to evaluate a sustainability standpoint (economic, environmental, and social), different biorefinery alternatives. This chapter reviews the important insights made into bioethanol production in Brazil. Technical configuration for 1G and 2G ethanol production and sustainability of ethanol (economic and environmental assessment) have also been discussed.

Use of the VSB to Assess Biorefinery Strategies

The VSB has been used to assess several configurations of sugarcane biorefineries, including first- and second-generation facilities with alternative features, such as harvesting extension with other crops and integrated production of sugar, ethanol, electricity, and chemicals like n-butanol, as well as thermochemical routes. In this chapter, in-depth examples of selected routes are provided in order to illustrate the different methods that can be applied for the sustainability impact assessment, as well as some results obtained with the VSB

Alternative Designs for Fixed Bed Catalytic Reactors

The scope of this paper is to explore the benefits of both conventional operation design co-current and counter-current, to propose a new alternative design for fixed bed catalytic reactor. Steady state and dynamic behavior were considered in the analysis. Additionally for the steady state, a study on the possible alternatives for the patterns of cooling fluid was also realized, searching for an efficient refrigeration, as well as, minimum energy cost, for the fixed bed catalytic reactor. These new alternative designs consist of using the main advantages of both conventional configurations in an unique design. The results show that the proposed alternative design for fixed bed catalytic reactor has considerable advance compared to conventional system.

Development of Rigorous and Reduced Heterogeneous Dynamic Models for Fixed Bed Catalytic Reactor and Three-Phase Catalytic Slurry Reactor

In this work, the dynamic behavior of two chemical reactors (Fixed Bed Catalytic Reactor and the Three-Phase Reactor), in which different reactions of great industrial interest take place, is presented. Rigorous and reduced models were developed and their capabilities to adequately predict the dynamic behavior of these reactors were compared, indicating which model is more suitable for a specific application (design, optimization and control). Different approaches [Classic, Hermite, Finlayson, Pirkle, Dixion, Generic and Orthogonal collocation (one point)] were used to obtain the reduced models. With these techniques, a mathematical order reduction was carried out, which eliminates the spatial co-ordinate (of the catalyst particle or of the reactor) and promotes radially lumped-differential formulations. The proposed rigorous models were able to predict the main characteristics of the dynamic behavior of the fixed bed catalytic reactor as well as of the three-phase reactor, including the inverse response phenomena and the hot spot present in the former. This knowledge is essential to design and control these reactors. The computational time demanded for the solution of the rigorous models is high in comparison to the reduced ones, which restricts the use of the rigorous models to cases where time is not a limiting factor. Otherwise, when on-line applications are required, the reduced models are more adequate. The models based on reduction techniques overcame computational burden with a faster and easier numerical solution, as well as other difficulties found in rigorous heterogeneous models, especially related to the large number of parameters and sophisticated numerical procedures required by the solution.

Sugar Extraction via Moving-Bed Diffusers in Ethanol Production Industry: Phenomenological Modeling and Finite-Volumes Simulation

This work proposes a steady-state two-dimensional phenomenological model for sugar extraction in industrial moving-bed diffusers. The mathematical formulation of the model is based on the theories of transport phenomena in porous media, which is an original and formal theoretical approach to describe sugar extraction in sugar cane beds. Averaging techniques were applied to convert the model equations into macroscopic mass balances over continuous volumes. The model was discretized by the finite volume method and solved by a supernodal LU factorization routine. In order to make the model and the solution procedure user-friendly, a computer-aided simulation framework was developed in the Python programming language. The outputs of this framework are extraction degree, °Brix curve, and °Brix distribution in the bed. This last output is unprecedented in literature. A real industrial moving-bed diffuser was used as a case study to demonstrate the capabilities of the simulation framework. Solution procedures of...

Sugar extraction by moving-bed diffusers in ethanol production: development of a simulation tool

Abstract In this work a simulator of a moving-bed diffuser was developed. Through this simulation tool it is possible to assess process behaviour, operation paths and design features of moving-bed diffusers, in order to improve the sugar extraction in diffusers. After the input of the required information (i.e., equipment, process and feed stock characteristics) the simulator produces the results, which are the Brix (soluble solids content in the liquid) curve and the Brix profile. The mathematical model of this extraction process includes the main features of liquid percolation through a bed of shredded cane and also the extraction mechanisms of lixiviation and diffusion. Finite-volumes method was applied as discretization procedure of the mathematical model. The parameters of this model were fitted using a hybrid method that assembles Differential Evolution and Flexible Polyhedron (Nelder-Mead). A full-scale moving-bed diffuser located in a Brazilian mill was used as a case study to evaluate the simulator performance. The simulator test reached its objectives, describing accurately the extraction process in the full-scale equipment. Being the Brix curve the traditional outcome for this process, the analysis of the Brix profile is presented as a new approach to evaluate the performance of moving-bed diffusers.