BMC Chemical Engineering最新文献

Separation process is very crucial in bioethanol production as it consumes the highest energy in the process. Unlike other works, this research systematically designed a suitable separation process for bioethanol production from corn stover by using thermodynamic insight. Two separation processes, i.e., extractive distillation (case 2) and pervaporation (case 3), were developed and compared with conventional molecular sieve (case 1). Process design and simulation were done by using Aspen Plus program. The process evaluation was done not only in terms of energy consumption and process economics but also in terms of environmental impacts. It was revealed that pervaporation is the best process in all aspects. Its energy consumption and carbon footprint are 60.8 and 68.34% lower than case 1, respectively. Its capital and production costs are also the lowest, 37.0 and 9.88% lower than case 1.

Synthetic paraffinic kerosene (SPK) is an ultra-clean fuel with low aromatic content and negligible quantities of sulfur compounds. Although, SPK has a good potential to replace the conventional fuel Jet A-1, it also has some deficiencies. One of them is the low lubricity compared to its conventional counterpart Jet A-1. To improve the lubricity of SPK, three selected additives have been mixed with SPK at different concentrations. The lubricity of the samples was determined experimentally and the samples that meet the industry specifications have been studied further. The effect of the additives on the physicochemical properties, such as, density, flash point, freezing point, viscosity, and heat content, were investigated. Linoleic acid was found to be an excellent lubricity improver even at a very low concentration and its negative impact on the other physicochemical properties was found to be insignificant. Ethyl oleate also demonstrated significant improvement in lubricity at low concentrations but had a negative impact on the fuel’s freezing point at high concentrations. Quinoline, at high concentrations, elevated the blend’s freezing point above the acceptable limits. In parallel to the experimental campaign, a pre-existing mathematical modelling tool was utilized to predict the properties of interest. The lubricity model was successfully introduced into the mathematical model in order to improve the capabilities of the model. Linoleic acid sample showed the best improvement in lubricity of SPK with wear scar diameter of 417?μm; well below the ASTM D7566 maximum limit of 850?μm. The dual nature of this study facilitated the optimization of the physicochemical properties of the fuel samples.

With the rapid rise in global population over the past decades, there has been a corresponding surge in demand for resources such as food and energy. As a consequence, the rate of waste generation and resultant pollution levels have risen drastically. Currently, most organic solid wastes are either land applied or sent to landfills, with the remaining fraction incinerated or anaerobically digested. However, with the current emphasis on the reduction of emissions, nutrient recovery, clean energy production and circular economy, it is important to revisit some of the conventional methods of treating these wastes and tap into their largely unrealized potential in terms of environmental and economic benefits. Wastewater sludge, with its high organic content and fairly constant supply, provides a great opportunity to implement some of these strategies using thermochemical conversion technologies, which are considered as one of the alternatives for upcycling such waste streams. This paper summarizes the results of prominent studies for valorizing wastewater sludge through thermochemical conversion technologies while drawing inferences and identifying relationships between different technical and operating parameters involved. This is followed by sections emphasizing the environmental and economic implications of these technologies, and their corresponding products in context of the broader fields of waste-to-energy, nutrient recycling and the progress towards a circular economy.

Retrosynthetic analysis is a canonical technique for planning the synthesis route of organic molecules in drug discovery and development. In this technique, the screening of synthetic tree branches requires accurate forward reaction prediction, but existing software is far from completing this step independently. Previous studies attempted to apply a neural network to forward reaction prediction, but the accuracy was not satisfying. Through using the Edit Vector-based description and extended-connectivity fingerprints to transform the reaction into a vector, this study focuses on the update of the neural network to improve the template-based forward reaction prediction. Hard-threshold activation and the target propagation algorithm are implemented by introducing mixed convex-combinatorial optimization. Comparative tests were conducted to explore the optimal hyperparameter set. Using 15,000 experimental reaction data extracted from granted United States patents, the proposed hard-threshold neural network was systematically trained and tested. The results demonstrated that a higher prediction accuracy was obtained than that for the traditional neural network with backpropagation algorithm. Some successfully predicted reaction examples are also briefly illustrated.

One fault that occurs with heat exchangers is a tube rupture, an overpressure scenario in which high pressure fluid flows into the low pressure region. It is a serious safety concern that may lead to significant damage. Accurate prediction of the pressure build-up after a rupture is critical to determine the appropriate size of a relief device and avoid exceeding allowable pressure limits. This paper describes a model-based step-by-step methodology to predict dynamic pressure profiles during tube rupture for liquid-liquid, vapor-liquid, and flashing liquid-liquid systems. The transient effects of the relief valve are considered. The effects of choked flow must also be considered for accurate maximum pressure predictions. Using a dimensionless analysis, the pressure ratio and density ratio are shown to significantly impact the severity of this incident. Results show that vapor-liquid systems result in the highest pressure surges.

It is critical for reliable infrastructure planning to address the Food-Energy-Water-Waste (FEW2) nexus at system level. This paper presents the applicability of resilience.io platform across water, energy and waste sectors (including food and agricultural waste) with focus on waste-to-energy pathway, aiming to establish the optimal FEW2 nexus based on economic and environmental indicators. A rich array of technology options, including water production facilities, clean energy technologies and waste-to-energy conversions are evaluated to meet the demand of water and energy (mainly gas and electricity), and the treatment requirement of waste and wastewater. A case study of Hunter Region, the largest region in Australia, is presented in this study, featuring the supply and demand context of developed countries. A full set of scenarios, including business-as-usual (BAU), water and wastewater, power plant decommission, waste-to-energy and policy intervention, is created to present FEW2 nexus from the perspective of individual nodes and the whole system. The results signal the benefits of biogas and syngas generation from anaerobic digestion and gasification for waste-to-energy pathway, alongside findings in water and energy sectors. The outcome of this analysis can then form the foundation of regional planning involving relevant stakeholders, with the modelling tools supporting scenario evaluation and collaborative learning to reach consensus in view of different performance indicators including financial and environmental metrics.

This paper presents a new method for process synthesis and economic assessment for solid drug product manufacturing, considering continuous manufacturing as a prominent process alternative. Of the three phases of drug development, phase II was targeted where the dosage form, formulation, and processing technology are determined. For a comprehensive alternative generation, a superstructure was developed that covered 9452 options for the unit level, which was combined with two options on the formulation strategy. The generated alternative was assessed by a net present value calculation model, which was adapted for dynamic cash flow consideration in the drug lifecycle. The model can incorporate uncertainty in the drug development and manufacturing in the result, and can perform global sensitivity analysis by Monte Carlo simulation. The method was demonstrated in a case study where two different scenarios regarding the price of the active pharmaceutical ingredient and the demand for the product were assumed. The results showed that when the demand and price are both low, the labor-related costs are dominant, and in the opposite case, the material-related costs become relevant. We also introduce the prototype version of the software “SoliDecision,” by which the presented method was implemented for industrial application.

This contribution presents an hourly-based optimization of a biogas supply network to generate electricity, heat and organic fertilizer while considering multiple objectives and auction trading prices of electricity. The optimization model is formulated as a mixed-integer linear programming (MILP) utilizing a four-layer biogas supply chain. The model accounts for biogas plants based on two capacity levels of methane to produce on average 1?±?0.1?MW and 5?±?0.2?MW electricity. Three objectives are put forward: i) maximization of economic profit, ii) maximization of economic profit while considering cost/benefits from greenhouse gas (GHG) emissions (economic^+GHG profit) and iii) maximization of sustainability profit. The results show that the economic profit accrued on hourly-based auction trading prices is negative (loss), hence, four additional scenarios are put forward: i) a scenario whereby carbon prices are steadily increased to the prevalent eco-costs/eco-benefits of global warming; ii) a scenario whereby all the electricity auction trading prices are multiplied by certain factors to find the profitability breakeven factor, iii) a scenario whereby shorter time periods are applied, and investment cost of biogas storage is reduced showing a relationship between cost, volume of biogas stored and the variations in electricity production and (iv) a scenario whereby the capacity of the biogas plant is varied from 1?MW and 5?MW as it affects economics of the process. The models are applied to an illustrative case study of agricultural biogas plants in Slovenia where a maximum of three biogas plants could be selected. The results hence present the effects of the simultaneous relationship of economic profit, economic^+GHG profit and sustainability profit on the supply and its benefit to decision-making.

With the concentration of CO₂ in the atmosphere increasing beyond sustainable limits, much research is currently focused on developing solutions to mitigate this problem. Possible strategies involve sequestering the emitted CO₂ for long-term storage deep underground, and conversion of CO₂ into value-added products. Conventional processes for each of these solutions often have high-capital costs associated and kinetic limitations in different process steps. Additionally, CO₂ is thermodynamically a very stable molecule and difficult to activate. Despite such challenges, a number of methods for CO₂ capture and conversion have been investigated including absorption, photocatalysis, electrochemical and thermochemical methods. Conventional technologies employed in these processes often suffer from low selectivity and conversion, and lack energy efficiency. Therefore, suitable process intensification techniques based on equipment, material and process development strategies can play a key role at enabling the deployment of these processes. In this review paper, the cutting-edge intensification technologies being applied in CO₂ capture and conversion are reported and discussed, with the main focus on the chemical conversion methods.

In this study, the conceptual process flowsheet was developed and the economic feasibility of woody biomass conversion to biofuel as feedstock was analysed by considering several promising experimental processes for lignin depolymerization, such as hydrodeoxygenation and hydrogenolysis, along with lignocellulosic biomass fractionation processes. The engineering simulation process toward the commercial production of bio-gasoline from lignocellulosic biomass using SuperPro Designer? was modeled. The compatibility of the end products with the current gasoline specifications was evaluated and various blending options were investigated to meet the octane number and Reid vapor pressure requirement of the product. The economic potential of the simulated engineering process was then evaluated from an economic perspective. The operating costs and capital investment of three scenario using three different catalytic systems were estimated and discussed to assess of the potential of commercializing of woody biomass valorization process. The main potential market segments were identified, including the process by-products such as xylose and cellulose pulp. From the economic evaluation study, it was found that selling the biomass fractionation products alone does have a greater profit than valorization of lignin to produce bio-gasoline, with net present value of RMB 22,653,000 and RMB 177,000, respectively at the same return on investment if the plant is set up in Hong Kong. It was also found that catalysts play a pivotal role in determination of the profitability in the valorization process, not only because of the price of the catalyst, but also the product distributions obtained with various types of it. To obtain the same gross profit, the sale price of bio-gasoline has to be set higher with platinum catalysts than with ruthenium catalysts (nearly 10 folds). Thus, catalyst development and process improvement are crucial in the establishment of bio-based circular economy.