Eco-efficient downstream processing of biobutanol by enhanced process intensification and integration

The biobutanol stream obtained after the fermentation step in the acetone-butanol-ethanol process has a low concentration (less than 3 wt % butanol) that leads to high energy usage for conventional downstream separation. To overcome the high downstream processing costs, this study proposes a novel intensified separation process based on a heat pump (vapor recompression)-assisted azeotropic dividing-wall column (A-DWC). Pinch analysis and rigorous process simulations have been used for the process synthesis, design, and optimization of this novel sustainable process. Remarkably, the energy requirement for butanol separation using heat integration and vapor recompression assisted A-DWC is reduced by 58% from 6.3 to 2.7 MJ/kg butanol

Dynamics and control of a heat pump assisted extractive dividing-wall column for bioethanol dehydration

Recently, a novel heat-pump-assisted extractive distillation process taking place in a dividing-wall column was proposed for bioethanol dehydration. This integrated design combines three distillation columns into a single unit that allows over 40% energy savings and low specific energy requirements of 1.24 kWh/kg ethanol. However, these economic benefits are possible only if this highly integrated system is also controllable to ensure operational availability. This paper is the first to address the challenges related to process dynamics and control of this highly integrated system. After showing the control difficulties associated with the original design owing to thermal unbalance, an efficient control structure is proposed which introduces a by-pass and an additional external duty stream to the side reboiler. The range of the external duty is rather small, about 5% of the combined duty of the reboilers, but sufficient to stabilize the system by controlling the temperature on the pre-concentration side of the column. Two quality control loops ensure product purity when the system is affected by feed flowrate and composition disturbances

Eco-efficient Downstream Processing of Biobutanol by Enhanced Process Intensification and Integration

The biobutanol stream obtained after the fermentation step in the acetone-butanol-ethanol process has a low concentration (less than 3 wt % butanol) that leads to high energy usage for conventional downstream separation. To overcome the high downstream processing costs, this study proposes a novel intensified separation process based on a heat pump (vapor recompression)-assisted azeotropic dividing-wall column (A-DWC). Pinch analysis and rigorous process simulations have been used for the process synthesis, design, and optimization of this novel sustainable process. Remarkably, the energy requirement for butanol separation using heat integration and vapor recompression assisted A-DWC is reduced by 58% from 6.3 to 2.7 MJ/kg butanol

Eco-efficient butanol separation in the ABE fermentation process

Butanol is considered a superior biofuel, as it is more energy dense and less hygroscopic than the more popular ethanol, resulting in higher possible blending ratios with gasoline. However, the production cost of the acetone-butanol-ethanol (ABE) fermentation process is still high, mainly due to the low butanol titer, yield and productivity in bioprocesses. The conventional recovery by distillation is an energy-intensive process that has largely restricted the economic production of biobutanol. Other methods based on gas stripping, liquid-liquid extraction, adsorption, and membranes are also energy intensive due to the bulk removal of water. This work proposes a new process for the butanol recovery by enhanced distillation (e.g. dividing-wall column technology) using only few operating units in an optimized sequence to reduce overall costs. A plant capacity of 40 ktpy butanol is considered and purities of 99.4 wt% butanol, 99.4 wt% acetone and 91.4 wt% ethanol. The complete downstream processing was rigorously simulated and optimized using Aspen Plus. The enhanced process is effective in terms of eco-efficiency (1.24 kWh/kg butanol, significant lower costs and emissions) and can be readily employed at large scale to improve the economics of biobutanol production

Rethinking the design of a 2-methoxy-2-methyl-heptane process by unraveling the true thermodynamics and kinetics

Among other fuel additives — such as MTBE, ETBE, or TAME — 2-methoxy-2-methyl heptane (MMH) can increase the fuel octane number and reduce the CO emission. MMH can be obtained through the exothermal etherification of 2-methyl-1-heptene and methanol. Lately, many researchers have developed more and more efficient processes considering the kinetics corresponding to an endothermal reaction. However, in this work we demonstrate that the reaction is actually quite exothermal, and this has strong impact on the designed process. Also, the vapor–liquid equilibrium data predicted by UNIQUAC model for 2-methoxy-2-methyl heptane and 2-methyl-2-heptanol mixture reveals that product purification is more difficult, and it requires more energy to recover and obtain MMH with high purity. Considering these aspects, the 54.87 ktpy process developed in this paper is more realistic and energy intensive (1.82 kW h/kg MMH), with a TAC of 5.3 M$/year. The controllability of the process is proven for ±20% changes of 2-methoxy-2-methyl-heptane production rate.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ChemE/Product and Process Engineerin