Process Flowsheet Research Articles

Techno-economic analysis of integrated hydrogen and methanol production process by CO2 hydrogenation

Global climate change is one of the major concerns of today's world. Indeed, the carbon capture and sequestration (CCS) has a great potential to abate global climate changes but the economic infeasibility of this process has motivated the researchers to develop methods for direct utilization of captured carbon dioxide (CO2) to value-added end products. For instance, the methanol production by hydrogenation of CO2 is extensively investigated for over two decades but the high operating cost of this process, especially for hydrogen production, has discouraged its commercial implementation. In this work, a high temperature solid oxide electrolyzer (SOE) as a source of hydrogen production (12.16 ton/hr) from steam is integrated with the CO2 hydrogenation process to reduce the cost of methanol production. Integration of SOE with methanol production process resulted into 22.3% reduction in the cost of hydrogen as compared to the alkaline water electrolyzer. Consequently, the cost of 63.5 ton/hr methanol production was reduced, from 1063 $/ton to 701.5 $/ton, by employing SOE and optimizing the process flowsheet (by considering seven different configurations of the flowsheet, along with heat and process integrations). It is anticipated that a further reduction in the cost of methanol production by aforementioned process is possible by the advancement of hydrogen production technology, especially the high performance materials development and commercialization of electrolyzers.

Process simulation and evaluation for NH3/CO2 separation from melamine tail gas with protic ionic liquids

Melamine production is known to produce a tail gas with a significant amount of NH3 and CO2. The most common separation methods applied to melamine tail gas are water scrubbing and urea co-production technology. With good stability, non-volatility and tailored properties, ionic liquids (ILs) are regarded as vital potential solvents for gas separation. Therefore, two new process technologies, one is the ionic liquid-based process (IL-0), and the other is the enhanced ionic liquid process (IL-En) was employed and evaluated for energy and cost efficiency. The IL-En employs stripping on the treatment of melamine tail gas. The protic ionic liquid named 1-butyl imidazolium bis (trifluoromethylsulfonyl) imide ([Bim][NTf2]) was selected for the evaluation of the melamine tail gas cleaning process. Thermodynamic data were fitted to the NRTL equations. Three full process flowsheets were simulated in Aspen Plus V11 TM. A basic and an enhanced ionic liquid process (IL-0 and IL-En), a conventional water scrubbing (WS) technology as a comparison, process sensitivity analysis and energy/economic evaluation were carried out. The results showed that the total separation cost of the IL-En can be reduced by 61% compared to that of the WS process. Moreover, the IL-based flowsheet is simpler than WS and avoids wastewater discharge.

Conceptual Process Design of an Integrated Xylitol Biorefinery With Value-Added Co-Products

This manuscript describes the conceptual process design of an integrated xylitol biorefinery with value-added co-products. Based on an existing three-step framework, the main product of a second-generation integrated biorefinery is chosen in the first stage. Based upon this, other decisions as the feedstock and value-added co-products are made. All relevant unit operations for the process are introduced. An initial superstructure with all potential process alternatives is composed of all introduced models. In the second step of the framework, a global sensitivity analysis is performed, firstly with coarse sampling to determine all viable flowsheet options and secondly with fine sampling to determine the most sensitive operational variables. As a result of the sensitivity analysis, most of the flowsheet options in the initial superstructure are not feasible. Based on these results, flowsheet sampling with the five most sensitive operational variables is performed to create surrogate models. In the scope of this work, three types of surrogate models are benchmarked against each other. Regarding the results of the superstructure optimization, firstly, it becomes apparent that the production of biokerosene does not contribute significantly to the net present value of the biorefinery. Furthermore, reducing the number of unit operations in the downstream processing leads to lower capital expenditures, but it lowers the product yield. Lastly, most flowsheets are economically feasible, indicated by a positive net present value. Based on this result, the most promising candidate process topology is subjected to the third step of the framework, including uncertainty in capital expenditure and operational expenses according to their estimations and uncertainties in the product prices. As a result, the net present value of the flowsheet turns negative, indicating that the high uncertainties for the expenditure and the expenses do not allow for an economically feasible operation. Lastly, the analysis of conceptually designed process flowsheets based on Monte Carlo sampling shows failure rates, with the NPV falling below the break-even point, of around 60% probability or higher. Based on these results, an economically feasible construction and operation of a xylitol biorefinery seems unlikely. Further ways to improve the metrics are elucidated.

Learning process patterns via multiple sequence alignment

Chemical process flowsheets contain a wealth of hidden information. By recognizing similarities in process flowsheets, engineers can understand how existing processes were designed and improve the design and operations of new processes. In previous work, we introduced a systematic methodology for comparing two flowsheets. Our present work proposes a novel method based on multiple sequence alignment to explore general patterns among multiple process flowsheets simultaneously without having to conduct pairwise comparisons of a given number of flowsheets. Additionally, we propose a decomposition strategy to identify inner patterns within a single flowsheet. Several case studies demonstrate that the proposed methodology can compare multiple flowsheets simultaneously to determine general patterns and effectively identify patterns from a single flowsheet.

Solvent extraction of Ni and Co from Ni-laterite leach solutions using a new synergistic system consisting of Versatic 10 acid, Mextral 6103H and Aliquat 336 with elemental mass balance for leaching, precipitation, solvent extraction, scrubbing and stripping

A new synergistic extraction system containing Versatic 10 acid, Mextral 6103H and Aliquat 336 was investigated for nickel and cobalt recovery from nickel laterite leach solutions. It was found that the addition of 0.3 M Aliquat 336 could significantly improve the nickel stripping kinetics of the Versatic 10 acid and Mextral 6103H mixed system, resulting in 98.9% stripping efficiency within 2 min. The effect of Aliquat 336 on the Versatic 10 acid (V10) and Mextral 6103H mixed system in terms of extraction and stripping performance was investigated. Based on the McCabe-Thiele plots for nickel/cobalt extraction and stripping, semi-continuous tests were conducted using the employed synergistic system. Over 99% nickel and 97% cobalt were extracted via a two-stage semi-continuous extraction with a pH profile of 4.5/5.0 for E1/E2 and an O/A ratio of 2.2, resulting in less than 2.0% manganese and negligible magnesium and calcium in the loaded organic solution. More than 95% co-extracted manganese was readily scrubbed via two stages of semi-continuous scrubbing, resulting in less than 1.0 mg/L Mn left in the scrubbed organic solution. Moreover, 98.8% nickel and 99.1% cobalt could be stripped using a two-stage semi-continuous stripping with 1.5 M H2SO4. Based on the test results, a proposed process flowsheet was developed for nickel and cobalt recovery and purification.

Srednekanskaya dike gold deposit in the northeast of Russia

This paper presents the results of a comprehensive material composition study of the host rocks and ores of the Srednekanskaya dike deposit. It has been found that the ores had been formed in several stages, namely, the metamorphogenic, hydrothermal-metasomatic (productive), and hypergene stages. At the same time, a decisive role in the formation of the gold mineralization was played by structural controls that are present in the form of breccias and hydrothermalmetasomatic alterations of rocks with gold deposition in the weakened zones. The prevailing features of gold mineralization of the Srednekanskaya dike are as follows: concentration of the bulk of gold in the vein material; predominant coarse gold occurrence as massive plates, lumps, and open-worked films; filling of interstitial openings in quartz, arsenopyrite, and pyrite with fine gold; native gold in quartz veins and quartz-carbonate-feldspar breccias localized in microdiorites confined to both arsenopyrite and pyrite and native gold associated with diorite-porphyry confined only to arsenopyrite, as supported by the geochemical data. Process studies have been carried out and the efficiency of Srednekanskaya dike ore processing by gravity methods has been established, with the gold recovery reaching 90 %. A recommended process flow sheet is presented.

Synthesis and characterization of fat-liquor from waste tallow

Abstract The fat-liquoring is an important step in leather making before dying to improve the glossiness, appearance, physical and chemical qualities of the leather. Synthetic sulphonated or sulphited oils are generally used to fill fibrous leather & to give it soft, elastic and loose characteristics. Natural fat-liquors (vegetable and animal-based) and synthetic fat-liquors are the two types of emulsions. The emulsion’s charge can be anionic, cationic, or nonionic. In this study, fat-liquor has been made from a bio-waste, namely tallow, which is obtained from a slaughterhouse as a byproduct of the animal hides and skin processing for leather. Triglycerides, a combination of oleic, stearic, and palmitic fatty acids, and glycerol make up the majority of this animal fat. Fat-liquor is made through a series of three reactions, namely, amidation, esterification, and sulphitation. Amidation helps to increase the hydroxyl groups. To react with fat, alkanol amine with a wide emulsifying characteristic isutilised. Anhydrides derived from di-carboxylic acids were then esterified with amidated fat in the next phase. By altering the process recipe, the stability of the emulsion product has been examined, and required raw materials are optimized. Finally, aqueous hydrolyzed sodium metabisulphite is used to sulphite the product, yielding bisulphite and hydroxide ions. The saponification and acid values are computed. The end product has a distinct advantage (anti-foaming & fire-retardant) over traditional fat-liquoring techniques. Material balance is performed once the process flow sheet was created. The process has been scaled up with the help of a preliminary reactor design. The degree of fat-liquoring and the process’ performance are revealed by FTIR spectrum. NMR was used to determine the final product’s structure.

Recovery of Rare Earth Metals (REMs) from Nickel Metal Hydride Batteries of Electric Vehicles

Nickel metal hydride (NiMH) batteries are extensively used in the manufacturing of portable electronic devices as well as electric vehicles due to their specific properties including high energy density, precise volume, resistance to overcharge, etc. These NiMH batteries contain significant amounts of rare earth metals (REMs) along with Co and Ni which are discarded due to illegal dumping and improper recycling practices. In view of their strategic, economic, and industrial importance, and to mitigate the demand and supply gap of REMs and the limited availability of natural resources, it is necessary to explore secondary resources of REMs. Therefore, the present paper reports a feasible hydrometallurgical process flowsheet for the recovery of REMs and valuable metals from spent NiMH batteries. More than 90% dissolution of REMs (Nd, Ce and La) was achieved using 2 M H2SO4 at 75 °C in 60 min in the presence of 10% H2O2 (v/v). From the obtained leach liquor, the REMs, such as Nd and Ce, were recovered using 10% PC88A diluted in kerosene at eq. pH 1.5 and O/A ratio 1/1 in two stages of counter current extraction. La of 99% purity was selectively precipitated from the leach liquor in the pH range of 1.5 to 2.0, leaving Cu, Ni and Co in the filtrate. Further, Cu and Ni were extracted with LIX 84 at equilibrium pH 2.5 and 5, leaving Co in the raffinate. The developed process flow sheet is feasible and has potential for industrial exploitation after scale-up/pilot trails.

Industrial recycling of end-of-life vehicle windshield glass by mechanical beneficiation and complete recovery of polyvinyl butyral

The environmental concern of end-of-life vehicles and stringent environmental regulation like the resource conservation and recovery act of the USA, and registration, evaluation, authorization, and restriction of chemicals act of EU and Korea mandates the recycling of the ELV. The EU-Directive 2000/53/EC on end-of-life vehicles was enacted in 2000, imposed a target to recycle for reuse and recovery at 85 and 80% by 2006; and then 95 and 85%, by 2015, respectively. Hence, recycling process development for each component like metal, plastic, glass, and rubber from end-of-life vehicles is essential. In the current investigation, an industrial-scale recycling process for end-of-life vehicle windshield glass has been developed for the recovery of polyvinyl butyral and glass components by mechanical beneficiation technique. In the developed process the industrial-scale recycling of end-of-life vehicle windshield glass and valorization of polyvinyl butyral broadly integrates two important processes i.e., (i) size reduction, and (ii) separation of constituent materials, and five different stages. The size reduction process involves (i) shredding and (ii) crushing followed by shredding. The separation process sequentially follows (i) polyvinyl butyral sheet and glass powder separation, (ii) crushing and gravity separation, and (iii) polyvinyl butyral recovery by rubbing and pressure washing process. The process flowsheet is developed for continuous operation with a capacity of up to 8–10 tons per day. An average of 98.86% of polyvinyl butyral recovery and 99.26% of glass recovery efficiency was achieved, which can be considered quantitative enough for industrial-scale recovery.

Optimal design of an MDEA CO2 capture plant for low-carbon hydrogen production — A rigorous process optimization approach

This work presents an optimized design of a methyl diethanolamine CO 2 capture unit for clean hydrogen production via steam methane reforming of natural gas, where CO 2 is captured from the pressurized water-gas shifted syngas. We propose a modified version of the standard MDEA-based CO 2 capture process flowsheet, and we optimize the operating conditions by solving a multi-objective optimization problem to minimize energy consumption while maximizing the CO 2 capture rate. In this paper, we opted to model the CO 2 capture plant using an equilibrium-based approach. To validate the optimization results obtained and to verify the absorber and desorber dimensions, we sized both columns. Packing heights remain below the threshold of 15 metres and productivity ranges between 0.74 t CO 2 /m 3 h at a capture rate of 90% and 0.35 t CO 2 /m 3 h for a CO 2 recovery of 99.8% respectively. • We propose a modified process configuration for an MDEA-based CO 2 capture unit for low-carbon H 2 production via steam methane reforming of natural gas. • The optimal set of operating conditions that minimizes the energy consumption of the process while maximizing the CO 2 capture rate are found by solving a multi-objective optimization problem. • Feasible column designs, with packing heights below the threshold of 15 metres, are possible even at high capture rates ( > 98 % ).

Process modelling and economic evaluation of biopropane production from aqueous butyric acid feedstock

Catalytic hydrothermal decarboxylation of biomass-derived butyric acid can produce renewable biopropane as a direct drop-in replacement fuel for liquefied petroleum gases. In this present study, experimental results from a batch reactor have been used to develop a hypothetical continuous process to deliver 20,000 tonnes/year of biopropane, as base-case capacity, from 10 wt% aqueous butyric acid. A combination of process synthesis and ASPEN Hysys simulation have been used to formulate a process flowsheet, after equipment selection. The flowsheet has been used to carry out economic analyses, which show that the minimum selling price of biopropane is $2.51/kg without selling the CO2 co-product. However, with the incorporation of existing UK renewable energy incentives, the minimum selling price can reduce to $0.98/kg, which is cheaper than the current $1.25/kg selling price for fossil liquefied petroleum gases. Sensitivity analysis based on raw material costs and production capacities show profound influence on the minimum selling price, with strong potentials to making biopropane competitive without incentivisation, whereas the influence of selling CO2 is marginal. While this biopropane technology appears promising, it still requires more detailed technical and process data, life-cycle analysis and detail economic costings and testing at a pilot-scale prior to commercial exploitation.

A review of the beneficiation of copper-cobalt-bearing minerals in the Democratic Republic of Congo

Copper and cobalt (Cu–Co) are strategic metals for the Democratic Republic of Congo (DRC), and nearly 20% of the country's GDP is supported by their exports. At present, the country classifies itself as the leading copper producer in Africa with an output in the region of a million tonnes and possesses nearly 60% of the world's reserves of Co; a metal exclusively exported in the form of salts or semi-finished products. Concentrators play a very important role in the growth of Cu–Co metal production, which is needed in order to meet rapidly growing global demand and to increase government revenues through mining royalties. This article reviews the major process flow sheets and reagent suites in practice at concentrators operated in the DRC for the beneficiation of Cu–Co values from various ore types. The comprehensive compilation of pertinent laboratory and industrial data is intended to provide practising specialists, metallurgists, and academics conducting research on Congolese Cu–Co ores with a single well-detailed reference source. Emphasis is placed on froth flotation as the major technique for the beneficiation of Cu–Co minerals.

Economically feasible decarbonization of the Haber-Bosch process through supercritical CO2 Allam cycle integration

The well-established Haber-Bosch (HB) process (industrial ammonia production) is a significant contributor to the world’s carbon emissions as it is a major consumer of natural gas as well as being energy-intensive in general. This work addresses the challenge of decarbonizing the HB process in a novel way as it, for the first time, presents a conceptual process integration with a supercritical CO2 Allam power cycle, therefore transforming gaseous CO2 emissions into a valuable side product in a form of liquid CO2. Detailed process design and flowsheet simulation using Aspen Plus ® was used as a basis for scale-up and techno-economic assessment of two cases (electrical grid dependent and independent). The results indicated that using this process design NH3 production reaches profitability at scales larger than 2 ton h−1 to 5.4 ton h−1 and at current global NH3 prices, the cost of manufacturing decrease, due to scale-up stabilizes at ∼ 30 ton h−1. Finally, this novel process integration achieves a significant reduction in gaseous CO2 emissions (compared to conventional HB process) of 68 % to 96 %, which indicates great potential for economically feasible green NH3.

Modeling and simulation process for solketal synthesis from glycerol and acetone by catalytic distillation in a modified structure of a divided wall column

The increasing biodiesel production generates important amounts of glycerol, by-product that require the development of new and sustainable processes in order to be converted into value added chemicals. In this paper special attention was given to possibility to transform glycerol into solketal, a promising fuel additive able to enhance stability to oxidation and increase the octane number of fuels. Given that the chemical reaction is thermodynamically limited, the current paper proposes a conceptual design of an industrial scale process flowsheet based on a modified structure of a catalytic distillation dividing wall column (CDDWC) in which acetone is used as a stripping agent, in an integrated reaction-separation structured-packing system. The modeling and simulation results performed in Aspen Hysys shown the technical feasibility, the glycerol conversion in the proposed process being over 99% and the purity of the solketal product over 99.5% (wt) with a high-quality utility (16 barg pressure steam) consumption of 2441 kJ/kg close to other values reported in the literature and an acetone specific consumption of 0.495 kg/kg solketal.

Efficiency Improvement in Sugar Mills through Bagasse Gasification

Biomass energy is useful in mitigating greenhouse gases as biomass growth captures CO2 from the atmosphere. This captured CO2 is eventually released upon the use of these biomass feedstocks, leading to a short duration carbon cycle. One prominent biomass feedstock is the sugarcane bagasse that is a by-product of sugar mills. Conventionally, the bagasse produced after crushing sugarcane is utilized in mills by directly burning it in the boilers. However, an efficient way of utilizing this biomass fuel would be through gasification. The biomass gasification process produces syngas which can be used as fuel for meeting the heat and power demands of the sugar mill, as well as surplus electricity, which can be supplied to the grid. The present study aims to highlight the efficiency improvement potential of bagasse gasification. The entire sugar mill as well as the bagasse gasification process, have been modeled in the ASPEN Plus® software. Heat integration has been performed to optimize the process flowsheets. The electrical energy generated by combusting bagasse is estimated to be 0.57 kWh/kg of bagasse combusted. In contrast, the gasification process can increase this energy generation up to 1.16 kWh/kg of bagasse at 10 % moisture content (by wt.). This study aims to provide awareness about the cleaner and efficient utilization of the energy that lies dormant in these industrial residues.

Simultaneous Optimization of an IGCC Process with Equation-Oriented Methods

Simultaneous optimization of process flowsheets using equation-oriented (EO) methods is a promising alternative to simulation studies. With the use of EO methods, simultaneous optimization of all process units including heat integration can be performed to achieve goals such as maximizing profit or minimizing operating costs. The use of EO methods required the development of new process models and equations of state (EOS), as algorithms and some formulations used in sequential methods do not work in an EO environment. Advancements in EO methods, along with the growth of gradient-based solvers, have enabled large-scale simultaneous flowsheet optimization. However, simultaneous process optimization still faces challenges as large problems, especially non-linear ones, may not achieve convergence without good initial values. A study on the simultaneous optimization of the integrated gasification and combined cycle (IGCC) process using EO methods was conducted as it is a combination of a cryogenic air separation unit (ASU), a coal gasifier and power generation units consisting of a combustor, a gas turbine, a heat recovery steam generator (HRSG) and a steam turbine. The purity of the oxygen product fed to the gasifier was often considered to be fixed in prior IGCC studies. With the ASU model and gasifier model used, the influence of oxygen purity and flowrate fed to the gasifier can be studied. The thermal efficiency of the IGCC process was maximized in GAMS using full-order EO process models. After the optimization, the thermal efficiency increased from 27.7 % in the base case to 36.7 %, with a notable change in process parameters, showing that the solver did not terminate close to the starting solution. Results showed that lowering the oxygen product purity from 95 % to 58.6 % increased the thermal efficiency of the IGCC process as the power required by the compressor in the ASU was reduced.

Insights into non-aqueous solvent extraction of gadolinium and neodymium from ethylene glycol solution using Cyanex 572

Comparison of the separation factors for Gd(III) over Nd(III) extraction from aqueous and non-aqueous ethylene glycol solutions using Cyanex 572 in kerosene. • Addition of water bridges the gap between hydrometallurgy and solvometallurgy. • Extraction of Gd(III) and Nd(III) from non-aqueous solution was compared with aqueous solution. • Gd and Nd extraction increases with increasing Cyanex 572 extractant concentrations. • Temperature had almost no effect on the extraction of both metal ions. • Under certain conditions, maximum separation factor was obtained and reached 22.09. The reprocessing of rare earth elements (REEs) by conventional hydrometallurgical processes remains a challenge because of the difficulties of separation. Solvometallurgy is a new non-aqueous solvent extraction approach including two immiscible organic phases which has been advanced for the extraction of rare earths. The less polar organic phase (LP) was a solution of Cyanex 572 (Cy-572) as an acidic extractant dissolved in kerosene. Whereas, the more polar organic phase (MP) was ethylene glycol with a limited amount of water dissolved in metal nitrate salts and lithium nitrate as a salting-out agent. The extraction of Gd(III) and Nd(III) from ethylene glycol solution was compared with extraction from an aqueous solution. The solvent extraction equilibrium was estimated by slope analysis method, and the composition of the Gd(III) extracted species in the less polar phase was proposed to be Gd(OH) L 2 . 2 HL ¯ . The non-aqueous system performs better separation of rare earths than the corresponding conventional extraction system. Subsequently, 0.1 mol/L HCl is the best stripping agent for both metal ions after two steps from the less polar phase, while a solution composed of 10% HF + 0.05 mol/L HCl is superior for nearly complete separation between the two elements. Eventually, the separation of binary mixtures of Gd(III) and Nd(III) is possible by this new non-aqueous solvent extraction system. A complete flow sheet process including extraction, scrubbing and stripping steps for the separation of Gd(III) and Nd(III) was proposed.

Thermal analysis of Indonesian copper sulphide

The development of extracting hydrometallurgical process for copper sulphide mineral becomes one of the promising fields, not only for the copper production but also for the production of metal by-products. The advantage of the thermal analysis is to get the phase form of the minerals on a certain temperature. With this result, the chosen metal can be selectively extracted. The goal of this study is to understand the thermal reaction of the copper sulphide as the basic data to develop a process flowsheet of extracting copper and other important metals from the copper concentrates by using an alternative new hydrometallurgy process to increase the value of the minerals. The thermal behaviour was investigated by simultaneous thermal analysis consisting of differential scanning calorimetry (DSC) in combination with thermo gravimetry (TG) and fourier transform infrared (FTIR) spectroscopy. Samples were pre-treated by roasting at the several temperature transitions and subsequently characterized by XRD and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS).

Development of an ecodesign framework for food manufacturing including process flowsheeting and multiple-criteria decision-making: Application to milk evaporation

The food industry urgently needs to design sustainability into its processes. Here we develop a methodological framework for the ecodesign of food processes. The framework combines process flowsheeting (using a process simulation tool) and multiobjective optimization with life-cycle and cost-cycle analysis tools embedded in a multicriteria decision support tool. The framework developed is illustrated by the example of milk evaporation, which is one of the most energy-intensive processes in the dairy industry and has huge potential for optimization. The commercial process simulator was first adapted to modeling milk evaporators. Economic and environmental criteria were then computed from inventories of both the production and cleaning phases, and we went on to apply multiobjective optimization (with a genetic algorithm) and multicriteria decision-making either independently or in combination. The potential of the framework was demonstrated first through analysis of three evaporator design solutions, and second as a support for the strategic choice of a fuel for the purpose of on-site energy production. This work provides a pathway to ecodesigning the entire milk powder production chain.

Обоснование схем расположения рабочих органов почвообрабатывающих орудий по критериям металлоемкости и тяговому сопротивлению

The results of laboratory and field studies to determine the quantitative characteristics of the change in the traction resistance of the working bodies depending on their operation conditions in the soil environment are provided. The values of the traction resistance of the working bodies operating in different cutting modes have been determined. A method is proposed for a comparative assessment of various process flow sheets of tools according to the criteria of metal consumption and traction resistance.