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K. Ojeda-Delgado ¹, Á. D. González-Delgado ², E. Sánchez-Tuirán ¹

Affiliations
1 Department of Chemical Engineering, Process Design and Biomass Utilization Research Group (IDAB), University of Cartagena, Cartagena, Bolívar, CO
2 Nano materials and Computer Aided Process Engineering Research Group (NIPAC), University of Cartagena, Cartagena, Bolívar, CO

Abstract

Background: Bioethanol is one of the most important biofuels because it has been produced from residual biomass such as corn stover, sugarcane bagasse, agricultural waste, among others. Bioethanol production from non-food biomass represents an opportunity for the biofuels industry to use raw materials in countries with high agricultural development, providing new alternatives for increasing the global production of biofuels. Therefore, process technologies have to be analyzed in order to guarantee the real energy gain in the biofuels industry through exergy analysis and computer-aided system engineering. Objectives: In this work, exergy analysis and heat integration methodologies were applied to evaluate hydrolysis and fermentation technologies when steam explosion pretreatment was used as pathway. Methods/Analysis: Bagasse from sugar industry was considered as raw material for bioethanol production. This residual lignocellulosic biomass was pretreated through catalyzed steam explosion and sent to different process configurations such as Separated Hydrolysis and Fermentation (SHF), Simultaneous Saccharification and Fermentation (SSF), and Simultaneous Saccharification and Co-Fermentation (SSCF). The three processes were analyzed using exergy analysis criteria and the best alternative was integrated to reduce heating and cooling utilities in the process and to improve the energy profile for the bioethanol process. Findings: It was found that the highest exergy efficient was obtained when SSCF technology was used after catalyzed steam explosion pretreatment in comparison with SHF and SSF alternatives. Application of heat integration methodologies reduced cooling utilities by 57.7% and heating utilities by 63.4%. Novelty/Improvement: Implementation of computer-aided process, heat integration and exergy analysis allowed to compare and evaluate bioethanol technologies in order to reduce the energy requirements for the biofuel process and increase the net energy gain.

Keywords

Bioethanol, Catalyzed Steam Explosion, Exergy, Heat Integration, Hydrolysis

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M. Ochoa-García ¹, L. Tejeda-López ¹, K. Ojeda-Delgado ¹, Á. D. González-Delgado ², E. Sánchez-Tuirán ¹

Affiliations
1 Department of Chemical Engineering, Process Design and Biomass Utilization Research Group (IDAB), University of Cartagena, Cartagena, Bolívar, CO
2 Department of Chemical Engineering, Nanomaterials and Computer Aided Process Engineering Research Group (NIPAC), University of Cartagena, Cartagena, Bolívar, CO

Abstract

Background: Microalgae have gained certain attention globally as feedstock for biodiesel production due to its fast growth rate and high potential yield of bio-fuel. Objectives: This work is focused on applying heat integration by thermal pinch point technique to a third generation biodiesel production process using Chlorella vulgaris as feedstock. Methods/Analysis: This case of study was simulated through commercial industrial process simulation software. A Cascade Diagram (CD) was constructed by defining temperature intervals and performing heat balance around them. The CD provided information about minimum cooling and heating utilities usage and maximum integrated heat exchange. In addition, a HEN was sensitized to achieve utilities targets. Findings: It was found that heat integration reduced cooling utilities and heating utilities by 38.67 and 100%, respectively, which reduces total operating costs when compared to base case. Novelty/Improvement: These results suggested that operating cost of biodiesel production from microalgae can be reduced by performing heat integration that represents an attractive process improvement for making biodiesel cost-competitive with other energy sources.

Keywords

Biodiesel, Heat Integration, Pinch Point, Utilities, CAPE

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K. Ojeda-Delgado ¹, M. Garcia-Giraldo ¹, M. A. Avila-Medina ¹

Affiliations
1 Chemical Engineering Department, Process Design and Biomass Utilization Research Group (IDAB), University of Cartagena, Cartagena, Bolívar, CO

Abstract

Objectives: The current research uses stems and leaves from corn stover for the application of urea pretreatment, in order to evaluate the most favorable conditions for the obtention of reducing sugars. Methods: Biomass particles with sizes of 0.5 and 2.0 mm were subjected to urea pretreatment (2.0 %w/v and 5.0 %w/v). Quantification of reducing sugars was performed using the DNS method and a calibration curve. Findings: The maximum value of total reducing sugars for the stems fraction (35.76 g/L) was reported when the particle size and the urea concentration were 0.5 mm and 5.0 %w/v, respectively. Corn stover leaves fraction obtained its highest result (59.65 g/L) using 0.5 mm particles size and 2.0 %w/v urea. Application/Improvements: This research contributes to the studies about urea pretreatment and its effect in different corn stover fractions.

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M. Ochoa-Garcia ¹, L. Tejeda-Lopez ¹, K. Ojeda-Delgado ¹, A. D. Gonzalez-Delgado ², E. Sanchez-Tuiran ¹

Affiliations
1 Department of Chemical Engineering, Process Design and Biomass Utilization Research Group (IDAB), University of Cartagena, Cartagena, Bolivar, CO
2 Department of Chemical Engineering, Nanomaterials and Computer Aided Process Engineering Research Group (NIPAC), University of Cartagena, Cartagena, Bolivar, CO

Abstract

Background: Exergy analysis has been recognized as a feasible approach to evaluate and improve industrial processes by identifying major irreversibilities in a system. Objectives: This work attempts to apply exergy analysis to a third-generation biodiesel production from Chlorella vulgaris microalgae. Methods/Analysis: Commercial industrial process simulation software was used to simulate this process. The specific exergy of many substances were found in literature and the others were calculated using Szargut, Morris & Steward’s equation. A global exergy balance around the system was carried out in order to determine total irreversibilities. The contribution of unit operations and equipment to total irreversibilities was also considered. In addition, exergy efficiency and exergy emission were calculated for each stage (pretreatment, reaction, separation, biodiesel purification, and glycerol treatment). Findings: The global exergy efficiency was calculated in 86% similar to the results reported in other researches. The equipment that contributes the most to total irreversibility was the separation column used to remove alcohol with 487.55 kJ/kg BD. In addition, the highest irreversibilities (5.22 MJ/kg BD) and exergy emission (2.71 MJ/ kg BD) per stage were reached during biodiesel purification. Novelty/Improvement: The application of exergy analysis allowed to identify potential improvements in this case of study, mainly in biodiesel purification stage and process modifications are suggested to reduce total irreversibilities as reutilizing methanol and glycerol streams.

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