Optimal Process Configurations of Bioethanol Dehydration for Different Ethanol Inlet Concentrations and Throughputs

Kanchanalai, Pakkapol; Park, Jongwoo; Kawajiri, Yoshiaki

doi:10.1016/b978-0-444-59507-2.50077-9

Cited by 1 publication

(8 citation statements)

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“…The table also shows a negligible change in the cost fraction of annualized capital cost of distillation while both the annualized capital cost and operating cost fraction of pervaporation moderately increases. This is because the separation partition more work to the pervaporation membrane as the feed concentration increases which has been described in our previous work …”

Section: Resultsmentioning

confidence: 59%

“…Huang et al , and Vane et al developed a new hybrid distillation-gas-permeation with vapor compression for ethanol purification which enables heat integration within the system. Our previous work shows that the hybrid D-PV membrane is favored over the gas-permeation system at a low ethanol feed concentration . Therefore, the D-PV system is chosen as the main separation for bioethanol dehydration in this work.…”

Section: Superstructure Of Separation Technologiesmentioning

confidence: 99%

“…For instance, the conversion using simultaneous saccharification and fermentation from lignocellulosic material can produce bioethanol of a concentration less than 5 wt %. , Fuel grade bioethanol has purity above 99 wt % and requires ethanol purification across the ethanol–water azeotropic point at around 95 wt %. Several technologies have been used for ethanol dehydration such as membrane pervaporation, adsorption, extractive distillation, or the hybrid distillation–membrane separation. , The choice of optimal separation technology may change depending on the feed concentration and throughput. , …”

Section: Introductionmentioning

confidence: 99%

“…This process does not require harvesting the algae and produces a contaminant free ethanol–water condensate . However, ethanol production from this route can be very dilute, ranging from 0.5–5 wt % and would require high energy consumption using conventional purification technology. , Figure depicts the energy consumption for ethanol purification to fuel grade at 99.4 wt % for different ethanol feed concentration using the optimal design of a hybrid distillation-membrane-pervaporation (D-PV) system derived from our previous work . The value includes the sensible heat to preheat the stream at different feed temperatures, and the ethanol purity of the stream leaving from the bottom of the distillation column must be less than 0.02 wt %.…”

Section: Introductionmentioning

confidence: 99%

“…8,9 The choice of optimal separation technology may change depending on the feed concentration and throughput. 10,11 Processes based on growing algae have gained a wide interest in biofuel production as an alternative renewable resource, since they can overcome some of the drawbacks of the first and second generation feedstocks. 4,6 One alternative is a cyanobacteria (blue−green algae) based process which uses photosynthesis to produce ethanol which is then collected from closed photobioreactors (PBRs) by evaporation and condensation driven by the diurnal thermal cycle.…”

Section: Introductionmentioning

confidence: 99%

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Cost and Energy Savings Using an Optimal Design of Reverse Osmosis Membrane Pretreatment for Dilute Bioethanol Purification

Kanchanalai

Lively²,

Park

et al. 2013

Ind. Eng. Chem. Res.

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The cost of dilute ethanol purification is a significant component of the overall cost for fuel grade ethanol production through fermentation or other biological routes. In this study, we consider bioethanol purification to the fuel grade in a closed system of photobioreactors (PBRs) that produce a dilute (0.5−5 wt %) ethanol solution, and where the water is recycled back to the reactors after separation. To reduce the energy consumption and hence the cost of dilute ethanol purification, a reverse osmosis (RO) membrane process is introduced as a potential pretreatment in order to purify ethanol−water mixtures to an intermediate concentration. The pretreated mixture is separated across the azeotropic point to the fuel grade by a hybrid distillation-membrane-pervaporation (D-PV) process. A superstructure of the overall separation process is formulated in the General Algebraic Modeling System (GAMS) environment as a mixed-integer nonlinear programming (MINLP) problem and optimized to minimize the total separation cost. The problem is posed with a constraint on the minimum ethanol recovery by the overall system. For dilute feeds, the steam used in the distillation reboiler dominates both the energy and the cost of the overall system. Installing the RO system reduces the steam usage at the expense of larger capital investment in membrane modules, which has been found to be optimal for dilute feeds below 3 wt % ethanol. The optimal number of membrane stages and the feed location of individual RO modules change at different feed concentrations and ethanol recoveries. The optimal process design results in a higher ethanol recovery by the main hybrid separation unit compared to the RO membrane process due to the high capital cost of an RO system to achieve a high recovery. Developing a cheaper RO membrane may further reduce the separation cost and may expand an optimal dilute feed concentration range.

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Section: Resultsmentioning

confidence: 59%