Phosphorous (P) is an essential element for living organisms and is predicted to be depleted within the next 100 years. Across the world, significant phosphorous losses due to its low utilization ...efficiency become one of the main reasons for water pollution. Struvite crystallization has been found to be a promising recovery technique to mitigate these problems, as the recovered precipitate can be used as a slow release fertilizer or raw material for chemical industry. Although this technique has been widely investigated over the past two decades, there are currently few real applications in industry. This paper addresses this issue by reviewing key aspects relevant to process design to pave the way for future application. It will help to narrow down struvite process design options and thus reduce the voluminous calculations for a detailed analysis. Struvite process development, research trend, product application and process economics are reviewed and a conceptual process design is provided. This analysis provides comprehensive information that is essential for future industrial struvite crystallization process design.
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•A trend analysis of current research on struvite crystallization was performed.•All factors affecting struvite crystallization were reviewed.•Current gaps and future research directions were identified.•A conceptual struvite crystallization process design was proposed.
The methanol (MeOH) steam reforming (MSR) process plays an important role in the MeOH-based international renewable energy supply chain. To address the challenges related to the high cost and ...substantial CO2 emissions linked to the state-of-the-art integrated MSR process, this study aims to propose and enhance an intensified MSR process focusing on energy utilization, economic viability and environmental impact. Aside from the MSR process, the overall scenario also includes the water–gas-shift reaction (WGS) process, CO2 capture using amine-based methods, liquefaction, and hydrogen purification through pressure-swing adsorption. Based on this study, apparent enhancements of the state-of-the-art MSR process can be achieved by adjusting key process variables, especially those related to the CO2 capture process, and by incorporating various intensification strategies, including heat integration (with feed-effluent heat exchangers) between the MSR and the WGS processes, implementing a side-draw intercooling structure of the CO2 absorber, splitting the rich solvent flow to the CO2 stripper, and employing a multi-stage CO2 stripper with vapor recompression. Compared to the state-of-the-art MSR process in the literature, the intensified MSR process produces ultra-pure hydrogen (99.99 mol%) as a main product while reduces 6.2 % of the shared cost (from 191.0 USD/t-MeOH to 179.1 USD/t-MeOH), increases the overall carbon capture rate by 3 % (from 86.73 % to 89.99 %), and reduces the direct CO2 emission by approximately 25 % (from 1.41 t-CO2/ t-MeOH to 1.06 t-CO2/ t-MeOH). Within a MeOH-based international renewable energy supply chain, these enhancements can also significantly lower the imported cost of electricity from 105.9 USD/MWh to 95.5 USD/MWh.
•A new hybrid process to bypass alyotrope.•Process simulation of antisolvent and evaporative crystallization.•Pilot plant experiments guided by simulated data.•Measurements of solubility, and phase ...diagram of quaternary system.•New graphical method to represent process paths inside a distribution diagram.
Separation of solid solution forming systems into their constituents using crystallization processes is very challenging. We demonstrate the separation of L–valine and L–leucine solid solutions using a new hybrid process of evaporation and antisolvent crystallization. This system of two amino acids is characterized by alyotropic behavior. Bypassing the alyotrope via proposed new method is the main feature of the process. The change of pure component solubilities and the composition of the alyotrope with addition of antisolvent (ethanol) is quantified. Based on these solubility measurements, empirical modelling and process simulation the concept was validated in a pilot plant scale. Moreover, Powder X-Ray Diffraction (PXRD), (pseudo)-ternary and Roozeboom diagrams are exploited to deepen process understanding. Additionally, a simple graphical determination of the supersaturation using the Roozeboom diagram is proposed and demonstrated. The successful isothermal bypassing of the alyotrope at larger scale can be directly integrated into a dual counter-current crystallization setup. To achieve further improvements, this concept can be combined with a similar concept based on bypassing the double saturation point by changing temperature.
The diafiltration-nanofiltration-reverse osmosis (DiaNF-RO) is an innovative process that aims to achieve ion fractionation of divalent/monovalent ions, i.e., Mg/Na (SF1Mg-Na), an important step ...towards resource recovery, while producing clean water in seawater desalination at a reasonable specific energy consumption (SEC). Firstly, the novelty of DiaNF-RO process is compared with the RO-DiaNF process where ion fractionation is performed at the pretreatment stage (i.e., seawater) in the former and post-treatment stage (i.e., SWRO brine) in the latter. DiaNF-RO outperforms RO-DiaNF in many aspects, including higher Mg recovery, higher SF1Mg-Na, lower scaling risk, and more efficient cost utilization, which emphasizes the benefits of initiating ion fractionation at low salinity in brine management. Secondly, the process practicality is reiterated by showing how desirable performance is achievable at low number of stages with some modifications. One possible adjustment is to improve NF membrane performance in the priority order of higher water permeability, lower Na rejection, and higher Mg rejection, which enables the 2DiaNF-RO to achieve the desirable SF1Mg-Na of 13.7 at 5.71 kWh/m3. Another possible adjustment is to integrate the 2nd RO stage for more product water recovery to achieve a competitive net SEC (4.01 kWh/m3). These results further solidify the industrial implementation possibility of the DiaNF-RO process.
Comparison between DiaNF-RO and RO-DiaNF, and enhancement of the 2DiaNF-RO process with improved NF membrane performance or 2nd RO integration. Display omitted
•Pre-treatment is more preferred than post-treatment for Mg/Na fractionation.•Pre-treatment has better cost utilization for ion fractionation.•Higher NF permeability triples the Mg/Na fractionation.•2nd RO stage integration reduces energy by 30 % at lower water cost.•Desirable 2DiaNF-RO performance emphasizes process practicality.
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•Chemical recycling of polystyrene using technology ready yields > 99 % pure styrene.•The process is thermodynamically (<10 MJ/kg) and economically competitive.•60% of virgin ...polystyrene can be replaced by chemical recycling.
Less than 5% of polystyrene is recycled, motivating a search for energy efficient and economical methods for polystyrene recycling that can be deployed at scale. One option is chemical recycling, consisting of thermal depolymerization and purification to produce monomer-grade styrene (>99%) and other co-products. Thermal depolymerization and distillation are readily scalable, well-established technologies; however, to be considered practical, they must be thermodynamically efficient, economically feasible, and environmentally responsible. Accordingly, mass and energy balances of a pyrolysis reactor for thermal depolymerization and two distillation columns to separate styrene from α-methyl styrene, styrene dimer, toluene, and ethyl benzene co-products, were simulated using ASPEN to evaluate thermodynamic and economic feasibility. These simulations indicate that monomer-grade styrene can be recovered with energy inputs <10MJ/kg, comparable to the energy content of pyrolysis co-products. Thermodynamic sensitivity analysis indicates the scope to reduce these values and enhance the robustness of the predictions. A probabilistic economic analysis of multiple scenarios combined with detailed sensitivity analysis indicates that the cost for recycled styrene is approximately twice the historical market value of fossil-derived styrene when styrene costs are fixed at 15% of the total product cost or less than the historical value when feedstock costs are assumed to be zero. A Monte Carlo and Net Present Value-based economic performance analysis indicates that chemical recycling is economically viable for scenarios assuming realistic feedstock costs. Furthermore, the CO2 abatement cost is roughly $1.5 per ton of averted CO2, relative to a pyrolysis process system to produce fuels. As much as 60% of all polystyrene used today could be replaced by chemically recycled styrene, thus quantifying the potential benefits of this readily scalable approach.
The ability to accurately model and simulate chemical processes has been paramount to the growing success and efficiency in process design and operation. These improvements usually come with ...increasing complexity of the underlying models leading to substantial computational effort in their use. It may also occur that the structure of the model is sometimes unknown making optimization and study difficult. To circumvent these issues, mathematically simpler models, commonly known as surrogate models, have been designed and used to successfully replace these complex, underlying models with much success. This technique has seen increasing use within the chemical process engineering field and this article summarizes some popular surrogates and their recent use in this area.
This article summarizes recent use of surrogate modeling in the chemical process engineering field and presents several examples found in the literature. Through the use of these mathematically simpler representations of complex functions or process simulations, the computational effort of optimization or study has simplified considerably.
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•The new processes for separating benzene/isopropanol/water is proposed.•Multi-objective genetic algorithm is applied to optimize the proposed processes.•The proposed hybrid ...reactive-extractive distillation processes have better economic and environmental performances.
The recycling of wastewater in chemical industry is of great significance because it can recover valuable organic solvents and prevent environmental pollution. In this work, benzene/isopropanol (IPA)/water ternary mixtures were separated by single and double reactive-extractive distillation column processes respectively. We conducted thermodynamic analysis on separation processes of ternary mixture to determine the feasible separation sequence. Furthermore, the processes are optimized by multi-objective genetic algorithm (MOGA) to obtain suitable operating conditions. And the processes were evaluated by the total annual cost (TAC), CO2 emissions (ECO2), extraction efficiency (Eext) and thermodynamic efficiency. The results showed that compared with the traditional triple column extractive distillation (TCED) process, the TAC and ECO2 of the double column reactive-extractive distillation (DCRED) process were dramatically reduced by 52.9% and 49.5%, respectively. Similarly, TAC and ECO2 decreased by 49.5% and 53.5% in reactive-extractive dividing wall column (REDWC) process compared with the traditional process. With application of intensive processes, the final proposed process is more economically and environmentally sustainable than the separation system proposed in currently available literatures. This study can provide reference for the efficient separation of industrial wastewater containing benzene and IPA.
Numerical control machining process design, which connects product design and modern manufacturing, is the extension of the design process in the process field. The process design intent, derived ...from in-depth part analysis, embodies the cognitive and strategic thinking of technologists in response to the specific design requirements during the process design. It encapsulates interpretable experiential knowledge and provides valuable insights for subsequent process design stages. However, the process design intent is the tacit experiential knowledge of technologists that implicitly exists in the process design, lacking a reasonable organizational framework and effective method to effectively represent and capture it. To fill this gap, a process design intent model for representing and capturing useful design intent knowledge for future reuse is developed and evaluated in this study. Firstly, this paper analyzes the existence of process design intent in process design and gives a brief description of the working scheme of the process design intent model. Then, the key modules of the model are introduced in detail and a knowledge graph of process design intent is built based on the model structure. Moreover, the process design intent annotator is developed to effectively capture process design intent. Finally, the example for capturing and representing process design intent is shown and the model is evaluated and discussed by the example.
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