Search

There has been an increasing interest in the conversion of biomass to biofuels, energy, and chemicals due to an increase in meeting environmental demands and price and decrease in the potential ava...

Production pathway sustainability assessment is an important step in promoting sustainability characteristics during early process design. This work proposes distillation intensified alternatives for the recovery of nylon industry effluents. The waste stream contains n-pentanol, cyclohexanone, and cyclohexene oxide (light oil). These products in their pure state are high added-value products. The generation of intensified alternatives is based on the inclusion of thermally coupling, column section movement, and column section elimination. All the alternatives are evaluated in various metrics that guarantee the sustainability of the process; Mass Intensity, E-Factor, Greenhouse Gas Emissions, Total Annual Cost, Controllability, and Inherent Safety. As a result, the intensified alternative with a thermal coupling turned out the most balanced process in light of sustainability indicators with energy requirements of 4.87 MJ/kgproduct and important improvement in sustainability indexes.

Butanol is an interesting biofuel and a product precursor, that could be obtained with acetone and ethanol via fermentation. The biofuels production has been identified as not economically competitive, thus, the parallel production of high value-added products, such as xylitol, could be an alternative to improve the profit. Xylitol can be produced from xylose, which might be considered as a coproduct in a second generation biorefinery. This study presents a systematic biorefinery process design for the simultaneous acetone, butanol, ethanol (ABE) and xylitol production, based on experimental and simulation approaches. Experiments were performed for the pretreatment of sugarcane bagasse and ABE fermentation. The simulation part used the experimental results and experimental data from literature, to perform rigorous calculations of the ABE and xylitol production process. The economic analysis (EA) was performed relying on some indicators such as, the net present value (NPV) and payback period (PBP); EA includes several scenarios for producing only ABE and some scenarios for simultaneous ABE and xylitol production. The results showed that the combined butanol and xylitol production could reduce by 17% the selling price of butanol, compared with only producing butanol. The study also included the combustion of residual solids and carbon dioxide depletion analyses. This approach illustrates the opportunity to perform a rigorous techno-economic analysis, to identify the feasibility of the process at industrial scale, based on realistic data. This approach was implemented for ABE and xylitol production, but it can be used to any other bioproduct.

Solar energy has become one of the most developed renewable energy sources in recent years. As with any energy source or product, there are health risks associated with the manufacturing of solar cells. And even though the photovoltaic industry uses far lesser amounts of toxic and flammable substances than many other industries, the use of hazardous chemicals can present occupational and environmental hazards. One of the most important aspects in the selection of new processes lies in the protection of workers’ health. Health risks can be reduced if a process is chosen properly and in preliminary phases. Since we have found that it is necessary to carry out an evaluation of the health risks to workers in the production of polycrystalline silicon for the manufacturing of photovoltaic cells, in this work we will use the Process Route Healthiness Index to quantify the health risk that each silicon production process represents (the higher the index, the higher the hazards). The polycrystalline silicon production processes evaluated with the healthiness index are: Siemens Process, Intensified Fluidized Bed Reactor Union Carbide Process, and Hybrid Process. Our results show that the Siemens Process is the healthiest process, but with the Process Route Healthiness Index values are closer to the Hybrid Process. Apart from this, a guide to the assessment of inherent occupational health hazards in SiSG production processes was also developed, which provides results alike those to the PHRI methodology.

The silicon industry is a source of various types of products, including materials for the implementation of renewable energy systems, with a comparatively lower environmental impact than conventio...

The separation stage is one of the most critical steps in a chemical process because it is at this stage where the product sales requirements are reached or where some important raw materials are recovered and reused. Nowadays, around 90% and 95% of the separations required in the chemical industry are carried out by distillation, which become it in the most used process separation, in particular for platform chemicals such as furfural. However, the distillation processes are characterized by enormous energy requirements, for this reason, a current tendency in separation processes is the search for new distillation schemes that can substantially reduce the energy consumption. In this sense, the thermally coupled distillation sequences are considered as some of the most important advances in the distillation field because this kind of arrangements can provide energy savings between 30% and 50% compared with the distillation sequences conventional, in the case of ternary mixtures. This chapter addresses some basic concepts for the design of thermally coupled distillation systems such as the remixing effect as well as current design methodologies, which can be easily implemented in process simulator programs.