[en] Highlights: • The water usage for hydrogen production from biomass and coal was explored. • The uncertainty analysis was carried out for water consumption of hydrogen production process. • The influence of major factors on total water consumption was demonstrated. • Constructive measures were proposed to improve the waste of water resources. Water is essential for the industrial production of hydrogen. This study investigates the production of hydrogen from biomass and coal. To date, there are few studies focusing on the water footprint of biomass-to-hydrogen and coal-to-hydrogen processes. This research conducted a life cycle water use analysis on wheat straw biomass and coal to hydrogen via pyrolysis gasification processes. The results show that the water consumption of the entire biomass-to-hydrogen process was 76.77 L/MJ, of which biomass cultivation was the dominant contributor (99%). Conversely, the water consumption of the coal-to-hydrogen process was only 1.06 L/MJ, wherein the coal production stage accounted for only 4.15% for the total water consumption, which is far lower than that of the biomass-to-hydrogen process. The hydrogen production stage of biomass hydrogen production accounted for 76% of the total water consumption when excluding the water consumption of straw growth, whereas that of the coal hydrogen production stage was 96%. This research provides the associated water consumption, within a specified boundary, of both hydrogen production processes, and the influence of major factors on total water consumption was demonstrated using sensitivity analysis.

[en] The selection of the extractant is an important consideration for the design of liquid–liquid extraction processes. Researchers are paying more attention to a priori predictions of liquid–liquid equilibria. The predictive and fully open-source thermodynamic model COSMO-SAC (conductor-like screening model-segment activity coefficient) uses quantum chemical calculations for calculating activity coefficients and thermodynamic properties. Through a brief review of the recent advances of COSMO-SAC in predicting liquid–liquid equilibrium of ionic liquid systems, this work assessed the accuracy of prediction for different chemical family combinations and generated directions for future improvement.

[en] Highlights: • The isobaric VLE data for EtOAc/DMSO, NPAC/DMSO and EtOAc/NPAC/DMSO were measured. • The NRTL and UNIQUAC and Wilson models were applied to correlate the studied system. • The binary interaction parameters were obtained for the three models. -- Abstract: Isobaric vapor-liquid equilibrium data were measured for three systems, namely, ethyl acetate + dimethyl sulfoxide, propyl acetate + dimethyl sulfoxide and ethyl acetate + propyl acetate + dimethyl sulfoxide at 101.3 kPa in this work. The experimental data were checked by the Van Ness (point-to-point test) and Herington (integral test) methods. The binary systems’ vapor-liquid equilibrium data tested by experiments were fitted well with the NRTL, UNIQUAC and Wilson models. The binary interaction parameters regressed by the three models and experimental data were accepted to predict vapor liquid equilibrium data of a ternary system. The maximum absolute deviations and mean absolute deviations between the experimental and thermodynamic model data were within a reasonable range, indicating that corrected binary interaction parameters can be used to accurately predict vapor-liquid equilibrium data of the ternary system.

[en] Highlights: • Two novel heat-pump-assisted pressure-swing distillation processes were explored. • The temperature-enthalpy diagram, stage-exergy and stage-deficit curves were studied. • The proposed distillation processes can improve the thermodynamic efficiency. -- Abstract: Pressure-swing distillation was investigated to separate ethanol/acetonitrile binary azeotrope. The parameters were optimized based on the minimum total annual cost. To implement cost saving, heat pump technology was applied to pressure-swing distillation process and two new pressure-swing distillation processes were explored and studied. The heat-pump-assisted pressure-swing distillation, which only needs a small amount of fresh heat steam, saves 62.8% of the operating cost compared with the pressure-swing distillation. The other process called double-heat-pump-assisted pressure-swing distillation, which needs no fresh heat steam, achieves an operating cost saving by 59.9%. To further analysis of thermodynamic efficiency, the temperature-enthalpy (T-H) diagram and stage-exergy and stage-deficit were studied. Payback period was introduced to evaluate the economy of the processes. The results showed that the payback periods of the new pressure-swing distillation processes are shorter than the suggested 15-year payback period by at least 7.5 years. Both the processes perform well on operating cost saving and they were economical for separating the ethanol/acetonitrile binary azeotrope.

[en] Highlights: • Municipal sludge plasma gasification-based hydrogen production systems are proposed. • Exergy, economic, and environmental analyses of the novel processes are conducted. • The municipal sludge-to-H₂ process has high production capacity. • Hydrogen production with synthetic chemical looping has excellent process performance. Aiming to solve the problems of the environment and land occupied by municipal sludge incineration and landfill technology, novel processes of municipal sludge-to-H₂ by plasma gasification and municipal sludge-to-H₂ by plasma gasification coupled with synthetic chemical looping processes are proposed to convert municipal sludge into H₂ and achieve carbon capture. On the basis of the simulation results, the performance of the two processes was explored through a comprehensive analysis of the process exergy efficiency, economic benefits, and environmental impact. The results show that the novel processes have higher energy conversion and utilization efficiencies. Municipal sludge-to-H₂ by the plasma gasification process has notable advantages in production capacity, which is 21.22% higher than that of municipal sludge-to-H₂ by plasma gasification coupled with synthetic chemical looping process. However, its exergy efficiency and financial internal rate of return are 6.98% and 4.59%, respectively, which is lower than those of municipal sludge-to-H₂ by plasma gasification coupled with synthetic chemical looping. In addition, its total capital investment, global warming potential, and acidification potential are 5.73%, 58.14%, and 16.59% higher than municipal sludge-to-H₂ by plasma gasification coupled with synthetic chemical looping. The proposed processes provide promising methods for solving the problems of municipal sludge treatment and the profitable and environmentally sustainable development of municipal sludge into H₂.

[en] Highlights: • The proposed control structure can achieve effective control and product yield. • Energy and exergy analysis are implemented to determine the passages of exergy loss. • Reactor operating conditions are optimized by sensitivity analysis. • The maximum C₆H₁₁NO yield is 99.86% and the minimum TAC is 5.988 × 10⁷ $ per year. -- Abstract: Cyclohexanone ammoximation is widely used as an efficient method to synthesize cyclohexanone oxime in industrial production. In this study, the cyclohexanone ammoximation production process was explored based on reaction kinetics in order to reduce its energy consumption and total annual cost. The effects of the reaction temperature, space time, and raw material ratios on the cyclohexanone oxime yield were analyzed. Under the optimized operating conditions, the maximum C₆H₁₁NO yield was 99.86%, and the minimum total annual cost was 5.988 × 10⁷ $ per year. Dynamic control of the cyclohexanone ammoximation production process was further explored under the optimized conditions. The proposed control structure could achieve effective control and maintain the desired product yield when flow rate and composition disturbances were introduced. The energy and exergy analyses of the cyclohexanone ammoximation process show that its energy efficiency can be improved from a thermodynamic perspective. The combination of a steady state simulation and dynamic control, thermodynamic analysis, and economic performance evaluation provide insight into the improvement and operation of the cyclohexanone oxime production process.

[en] Highlights: • The potential extractant was selected based on separation mechanism. • Dividing-wall column and pervaporation were used to reduce energy consumption. • Multi-objective optimization was used to balance between economics and thermodynamics. • The dynamics and control strategy of the process was further explored. • The economics of pervaporation and distillation vary with the water content. Cyclohexane and isopropanol (IPA) are commonly used as solvents for rapeseed oil peeling and low-temperature pressing. Owing to the existence of azeotropes, it is difficult to achieve efficient separation of wastewater by ordinary distillation. The theory of thermodynamics and molecular dynamics was used to explore the separation mechanism and identify optimal extractants. Furthermore, extractive dividing-wall column and pervaporation (PV) technology were used to decrease the energy consumption in the recovery process. Thermodynamic performance and environmental assessments were used to analyze the processes. Taking the total annual cost (TAC) and exergy as the objective, the processes were optimized by multi-objective optimization. The results showed that the TAC and CO₂ emissions of the extractive dividing-wall column process were reduced by 7.46% and 5.89%, compared with the basic process. The TAC and CO₂ emissions of the PV extractive distillation process were reduced by 13.98% and 15.09%. On this basis, the dynamic control performance was further explored by introducing a ±10% feed flow and composition disturbance. In addition, the influence of the composition on the economics of PV and distillation was studied. It was found that the PV-extractive distillation process has significant advantages over the basic process in the separation of azeotropes.

[en] Highlights: • Biomass-to-hydrogen (BTH) shows better performances on production cost. • Coal-to-hydrogen (CTH) shows better performances on raw material consumption and TCI. • Techno-economic performance of CTH and BTH is conducted and compared. • BTH has a superior performance in terms of its resistance to price risk than CTH process. -- Abstract: Hydrogen is a key raw material for many chemical processes and a clean fuel for various power generation strategies. Coal-to-hydrogen (CTH) conversion is an alternative way to produce hydrogen that is applicable to the abundant coal reserves in China. The use of fossil energy has contributed to severe environmental problems, which drives the development of potential hydrogen production processes. Biomass is a promising renewable energy as well as an attractive resource for producing hydrogen, and it may address some of these environmental problems. In this paper, the simulation results of the biomass-to-hydrogen (BTH) and CTH processes were validated using available experimental data from the literature. Based on the simulation results, a techno-economic analysis was conducted from the viewpoints of the first and second laws of thermodynamics. The techno-economic analysis included determination of the energy efficiency, material consumption, total capital investment, production cost and carbon tax. The energy efficiencies of BTH and CTH were 37.88% and 37.82%, respectively. The BTH process had a larger raw material consumption and total capital investment (TCI) than the CTH process. However, the BTH process had a lower production cost and GHG emissions than the CTH process. The results of energy analyses of the BTH and CTH processes showed that the energy efficiency can be improved from a thermodynamic perspective. The combination of thermodynamic analysis and techno-economic performance evaluation provides insights into the improvement and operation of clean hydrogen production.