The Experts below are selected from a list of 115251 Experts worldwide ranked by ideXlab platform
Guido Zacchi - One of the best experts on this subject based on the ideXlab platform.
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enzymatic hydrolysis and simultaneous saccharification and fermentation of steam pretreated spruce using crude trichoderma reesei and trichoderma atroviride enzymes
Process Biochemistry, 2009Co-Authors: Krisztina Kovacs, George Szakacs, Guido ZacchiAbstract:The aim of this study was to compare the performance of the enzymes produced by Trichoderma reesei Rut C30 and the good extracellular beta-glucosidase-producing mutant Trichoderma atroviride TUB F-1663 to that of commercial preparations in the enzymatic hydrolysis and the simultaneous saccharification and fermentation (SSF) of steam-pretreated spruce (SPS). The concentrated TUB F-1663 enzyme was found to be the most efficient in the hydrolysis of washed SPS at 50 g/L water-insoluble solids (WIS) in terms of the glucose produced (18.5 g/L), even in comparison with commercial cellulases (14.1-16.7 g/L). The enzyme preparations were studied at low enzyme loadings (5 FPU/g WIS) in SSF to produce ethanol from SPS. The enzyme supernatant and whole fermentation broth of T. atroviride as well as the whole broth of T. reesei proved to be as efficient in SSF as the commercial cellulase mixtures (ethanol yields of 61-76% of the theoretical were achieved), while low ethanol yields (<40%) were obtained with the beta-glucosidase-deficient T. reesei supernatant. Therefore, it seems, that instead of using commercial cellulases, the TUB F-1663 enzymes and the whole broth of Rut C30 may be produced on-site, using a Process Stream as carbon source, and employed directly in the biomass-to-bioethanol Process. (C) 2009 Elsevier Ltd. All rights reserved. (Less)
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bioethanol production from non starch carbohydrate residues in Process Streams from a dry mill ethanol plant
Bioresource Technology, 2008Co-Authors: Marie Linde, Mats Galbe, Guido ZacchiAbstract:Slurries obtained from Process Streams in a starch-to-ethanol plant, Agroetanol AB in Norrkoping, Sweden, were used to assess the potential increase in bioethanol yield if heat treatment followed by enzymatic hydrolysis were applied to the residual starch-free cellulose and hemicellulose fractions. The effects of different pretreatment conditions on flour (the raw material), the Stream after saccharification of starch, before fermentation, and after fermentation were studied. The conditions resulting in the highest concentration of glucose and xylose in all Streams were heat treatment at 130 degrees C for 40min with 1% H(2)SO(4). Mass-balance calculations over the fermentation showed that approximately 64%, 54%, 75% and 67% of the glucan, xylan, galactan and arabinan, respectively, in the flour remained water insoluble in the Process Stream after fermentation without any additional treatment. Utilizing only the starch in the flour would theoretically yield 425L ethanol per ton flour. By applying heat pretreatment to the water-insoluble material prior to enzymatic hydrolysis, the ethanol yield could be increased by 59L per ton flour, i.e. a 14% increase compared with starch-only utilization, assuming fermentation of the additional pentose and hexose sugars liberated. (Less)
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bioethanol production from non starch carbohydrate residues in Process Streams from a dry mill ethanol plant
Bioresource Technology, 2008Co-Authors: Marie Linde, Mats Galbe, Guido ZacchiAbstract:Slurries obtained from Process Streams in a starch-to-ethanol plant, Agroetanol AB in Norrkoping, Sweden, were used to assess the potential increase in bioethanol yield if heat treatment followed by enzymatic hydrolysis were applied to the residual starch-free cellulose and hemicellulose fractions. The effects of different pretreatment conditions on flour (the raw material), the Stream after saccharification of starch, before fermentation, and after fermentation were studied. The conditions resulting in the highest concentration of glucose and xylose in all Streams were heat treatment at 130 degrees C for 40 min with 1% H(2)SO(4). Mass-balance calculations over the fermentation showed that approximately 64%, 54%, 75% and 67% of the glucan, xylan, galactan and arabinan, respectively, in the flour remained water insoluble in the Process Stream after fermentation without any additional treatment. Utilizing only the starch in the flour would theoretically yield 425 L ethanol per ton flour. By applying heat pretreatment to the water-insoluble material prior to enzymatic hydrolysis, the ethanol yield could be increased by 59 L per ton flour, i.e. a 14% increase compared with starch-only utilization, assuming fermentation of the additional pentose and hexose sugars liberated.
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recirculation of Process Streams in fuel ethanol production from softwood based on simultaneous saccharification and fermentation
Applied Biochemistry and Biotechnology, 2002Co-Authors: Malek Alkasrawi, Mats Galbe, Guido ZacchiAbstract:The effect of Process Stream recirculation on ethanol production from steam- pretreated softwood based on simultaneous saccharification and fermentation (SSF) was investigated for two Process configurations. In the first configuration, a part of the stillage Stream after distillation was recycled and, in the second configuration, the liquid after SSF was recycled. The aim was to minimize the energy consumption in the distillation of the fermentation broth and in the evaporation of the stillage, as well as the use of fresh water. However, recirculation leads to an increased concentration of nonvolatiles in the first configuration, and of both volatiles and nonvolatiles in the second configuration. These substances might be inhibitory to the enzymes and the yeast in SSF. When 60% of the fresh water was replaced by stillage, the ethanol yield and the productivity were the same as for the configuration without recirculation. The ethanol production cost was reduced by 17%. In the second configuration, up to 40% of the fresh water could be replaced without affecting the final ethanol yield, although the initial ethanol productivity decreased. The ethanol production cost was reduced by 12%. At higher degrees of recirculation, fermentation was clearly inhibited, resulting in a decrease in ethanol yield while hydrolysis seemed unaffected.
Christos T Maravelias - One of the best experts on this subject based on the ideXlab platform.
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an optimization based approach for simultaneous chemical Process and heat exchanger network synthesis
Industrial & Engineering Chemistry Research, 2018Co-Authors: Lingxun Kong, Christos T MaraveliasAbstract:We propose a mixed-integer nonlinear programming (MINLP) model for simultaneous chemical Process and heat exchanger network synthesis. The model allows Process Stream inlet/outlet temperatures and flow rates to vary and can be extended to handle unclassified Streams, thereby facilitating integration with a Process synthesis model. The proposed model is based on a generalized transshipment approach in which the heat cascade is built upon a “dynamic” temperature grid. Both hot and cold Streams can cascade heat so that exchanger inlet and outlet temperature, heat duty, and area can be calculated at each temperature interval. We develop mixed-integer constraints to model the number of heat exchangers in the network. Finally, we present several solution strategies tailored to improve the computation performance of the proposed models.
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An Optimization-Based Approach for Simultaneous Chemical Process and Heat Exchanger Network Synthesis
2018Co-Authors: Lingxun Kong, Christos T MaraveliasAbstract:We propose a mixed-integer nonlinear programming (MINLP) model for simultaneous chemical Process and heat exchanger network synthesis. The model allows Process Stream inlet/outlet temperatures and flow rates to vary and can be extended to handle unclassified Streams, thereby facilitating integration with a Process synthesis model. The proposed model is based on a generalized transshipment approach in which the heat cascade is built upon a “dynamic” temperature grid. Both hot and cold Streams can cascade heat so that exchanger inlet and outlet temperature, heat duty, and area can be calculated at each temperature interval. We develop mixed-integer constraints to model the number of heat exchangers in the network. Finally, we present several solution strategies tailored to improve the computation performance of the proposed models
Lingxun Kong - One of the best experts on this subject based on the ideXlab platform.
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an optimization based approach for simultaneous chemical Process and heat exchanger network synthesis
Industrial & Engineering Chemistry Research, 2018Co-Authors: Lingxun Kong, Christos T MaraveliasAbstract:We propose a mixed-integer nonlinear programming (MINLP) model for simultaneous chemical Process and heat exchanger network synthesis. The model allows Process Stream inlet/outlet temperatures and flow rates to vary and can be extended to handle unclassified Streams, thereby facilitating integration with a Process synthesis model. The proposed model is based on a generalized transshipment approach in which the heat cascade is built upon a “dynamic” temperature grid. Both hot and cold Streams can cascade heat so that exchanger inlet and outlet temperature, heat duty, and area can be calculated at each temperature interval. We develop mixed-integer constraints to model the number of heat exchangers in the network. Finally, we present several solution strategies tailored to improve the computation performance of the proposed models.
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An Optimization-Based Approach for Simultaneous Chemical Process and Heat Exchanger Network Synthesis
2018Co-Authors: Lingxun Kong, Christos T MaraveliasAbstract:We propose a mixed-integer nonlinear programming (MINLP) model for simultaneous chemical Process and heat exchanger network synthesis. The model allows Process Stream inlet/outlet temperatures and flow rates to vary and can be extended to handle unclassified Streams, thereby facilitating integration with a Process synthesis model. The proposed model is based on a generalized transshipment approach in which the heat cascade is built upon a “dynamic” temperature grid. Both hot and cold Streams can cascade heat so that exchanger inlet and outlet temperature, heat duty, and area can be calculated at each temperature interval. We develop mixed-integer constraints to model the number of heat exchangers in the network. Finally, we present several solution strategies tailored to improve the computation performance of the proposed models
Christodoulos A Floudas - One of the best experts on this subject based on the ideXlab platform.
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heat exchanger network synthesis without decomposition
Computers & Chemical Engineering, 1991Co-Authors: Amy R Ciric, Christodoulos A FloudasAbstract:Most of the grassroot heat exchanger network (HEN) synthesis approaches decompose the synthesis problem into a series of three major tasks: (a) minimum utility cost calculation; (b) selection of the fewest number of matches; and (c) determination of a minimum investment cost HEN. This paper departs fro these approaches by posing the HEN synthesis problem as a single optimization problem, whose solution provides simultaneously the optimal utility consumption level, matches and network configuration. This approach alleviates the need for either estimating the optimal utility levels via targetting schemes, or for performing several optimization loops to determine the optimal utility consumption level and Process Stream matches. The approach can be applied to both pseudo-pinch and strict-pinch design problems. The proposed approach compares favorably with: (a) decomposition techniques; (b) with the simulated annealing approach; and (c) with other simultaneous approaches. The method is illustrated with three example problem
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heat exchanger network synthesis without decomposition
Computers & Chemical Engineering, 1991Co-Authors: Amy R Ciric, Christodoulos A FloudasAbstract:Most of the grassroot heat exchanger network (HEN) synthesis approaches decompose the synthesis problem into a series of three major tasks: (a) minimum utility cost calculation; (b) selection of the fewest number of matches; and (c) determination of a minimum investment cost HEN. This paper departs fro these approaches by posing the HEN synthesis problem as a single optimization problem, whose solution provides simultaneously the optimal utility consumption level, matches and network configuration. This approach alleviates the need for either estimating the optimal utility levels via targetting schemes, or for performing several optimization loops to determine the optimal utility consumption level and Process Stream matches. The approach can be applied to both pseudo-pinch and strict-pinch design problems. The proposed approach compares favorably with: (a) decomposition techniques; (b) with the simulated annealing approach; and (c) with other simultaneous approaches. The method is illustrated with three example problem
Atsushi Tsutsumi - One of the best experts on this subject based on the ideXlab platform.
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a novel cryogenic air separation Process based on self heat recuperation
Separation and Purification Technology, 2011Co-Authors: Yasuki Kansha, Akira Kishimoto, Tsuguhiko Nakagawa, Atsushi TsutsumiAbstract:In this paper, a novel cryogenic air separation Process that reduces energy consumption by self-heat recuperation is proposed. In the proposed cryogenic air separation Process, heat from the top vapor Stream of the column is recuperated and exchanged with heat in the bottom liquid and feed Streams, using self-heat recuperation technology. As a result, not only the latent heat but also the sensible heat of the Process Stream is circulated in the Process. Furthermore, the pressure in the column can be decreased compared with the high pressure part of a conventional cryogenic air separation system, in which high and low pressure columns are combined to exchange nitrogen latent heat with oxygen latent heat. Thus, the energy input to the main compressor located before the column can be dramatically reduced. A simulation demonstrated that the energy consumption of the proposed cryogenic air separation Process with self-heat recuperation decreased by more than 36% compared with the conventional cryogenic air separation Process, when producing 99.99 mol% oxygen from air.
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advanced energy saving in the reaction section of the hydro desulfurization Process with self heat recuperation technology
Applied Thermal Engineering, 2010Co-Authors: Kazuo Matsuda, Yasuki Kansha, Kenichi Kawazuishi, Yoshiichi Hirochi, Rei Sato, Chihiro Fushimi, Yutaka Shikatani, Hiroshi Kunikiyo, Atsushi TsutsumiAbstract:Abstract The reaction section of the naphtha hydro-desulfurization (HDS) Process is a heating and cooling thermal Process consisting of a feed/effluent heat exchanger and a fired heater. Energy savings are fundamentally made as a result of the maximized heat recovery in the heat exchanger and the reduced heat duty of the fired heater. To achieve further energy saving in the Process, “self-heat recuperation technology” (SHRT) was adopted. In this technology, a compressor was introduced. The suction side of the compressor needed a lower pressure and the feed Stream evaporated much easily. The discharged side of the compressor satisfied the operating conditions of both pressure and temperature at the inlet of the reactor. And the reactor effluent Stream was able to be used completely to preheat and vaporize the feed Stream. All the heat in the Process Stream was re-circulated without using a fired heater. SHRT was applied to the naphtha HDS Process of 18,000 barrel per Stream day (BPSD) in the refinery and the mass and energy balance of the Process was calculated using commercially available simulation software, Invensys PROII version 8.1. This Process-simulation case study confirmed that despite there being no more energy saving potential in the conventional Process that makes use of a fired heater, the advanced Process with SHRT can reduce the energy consumption significantly by using the recuperated heat of the feed Stream.
