Batch processes are relevant to a wide variety of industries in chemical processes. In batch operations, water sources are almost not directly reused/recycled in process sinks without considering ...time constraints and storage tanks. However, storage tanks are usually expensive and thus a cost-effective water system has to be synthesized. Rescheduling the water network can contribute to reducing the cost of storage tanks by reducing their number and capacity. In the current research work, a goal programming is used to reschedule the water network in batch processes considering the time and storage tanks. A Mixed Integer Non-Linear Program model is introduced using the Lingo optimization program. This model is used to optimize multiple objectives, which are freshwater usage, wastewater discharge, the number and capacity of tanks, the degree of shifting streams, and the total cost of the water network. Three case studies are presented in this study to demonstrate the effectiveness of the proposed procedure, considering both single and multi-contaminants problems. The results of the first case study show a reduction in the network cost and the freshwater flowrate by 26.4% and 42%, respectively. Regarding the rescheduled water network results of the second case study, the cost is reduced by 24.6% and the freshwater flowrate is decreased by 21.8% with no requirement of storage tanks. The third case study highlights the model's applicability to multi-contaminants problem, revealing a 15.1% cost reduction and a 25.7% decrease in freshwater flow.
This paper presents a simulation technique for optimizing a hydrogen integration network. By applying this technique, the minimum fresh hydrogen consumption can be determined. Quantitative ...relationship between sources and sinks streams were studied to get the flow rates of coupled source and sink, hydrogen consumption and hydrogen concentration in each stream. The introduced technique was applied on twelve sources and twelve sinks with any purity of hydrogen concentration. The hydrogen integration network was designed through two steps, the first step considers applying the data given in the LINGO program, while the second step considers using the LINGO results in the introduced excel program to obtain the retrofitted hydrogen integration network. The proposed technique was applied on several case studies to achieve the minimum consumption of fresh hydrogen for the obtained hydrogen integrated networks. The introduced model for simulation and retrofitting of mass exchange networks is easy to understand and the results showed that this model is more efficient for fertilizer, petrochemical and refinery plants.
A simulation study to predict and optimize a natural gas steam reforming plant in Suez was performed. The developed model was used to generate performance data that would map the relation between ...atthe operating variables and hydrogen productivity. A single objective optimization problem was then formulated to maximize hydrogen production in the subunits: hydrocarbon prereformer, steam methane reformer, and the medium‐temperature water‐gas‐shift reactor. The process temperature and pressure for the three subunits, total plant flow rate and total superheated steam flow rate were selected as decision variables. A good agreement was found between simulation results and plant data at steady‐state conditions in terms of hydrogen yield and chemical composition. The developed mathematical model for hydrogen productivity correctly predicts the effect of relevant process parameters.
A simulation study is presented for a natural gas steam reforming plant. Simulation results were validated against plant data under steady‐state conditions. A simulation tool was developed to identify the optimal operating conditions and predict the plant hydrogen productivity. Optimized conditions for the complete industrial hydrogen plant maximize the added value and minimize the running cost.
A natural gas (NG) dehydration unit based on glycol absorption is considered one of the most important gas processing units, aiming to decrease water content and consequently adjust its dew point. ...However, during this process, not only water is absorbed by the glycol solvent, but also some aromatic compounds, including benzene, toluene, ethylbenzene, and xylene (BTEX), in addition to volatile organic compounds (VOC), are absorbed. These compounds are released during glycol regeneration into the atmosphere, resulting in environmental pollution and consequent catastrophic mental and physical health problems. This study aims to minimize BTEX emissions while ensuring efficient dew point control. Various strategies have been adopted to control BTEX emissions, but the present work focuses on optimizing operating conditions and investigating the influence of operational variables on BTEX emissions, as well as NG water content. LINGO optimization software and HYSYS (version 11) are used to find the plant’s optimum conditions for minimizing BTEX emissions and satisfying efficient dew point control. Simulation results show that stripping gas, triethylene glycol (TEG) circulation rate, and inlet feed gas temperature significantly affect BTEX emissions. The proposed optimum operating conditions in this work resulted in a reduction in BTEX emissions by about 81% while satisfying the required NG dew point. Furthermore, two quadratic equations are developed based on regression analysis for efficient calculation of the BTEX emissions and water dew point at any operational variables.
Controlling the distribution of water and wastewater between industrial processes is vital to rationalize water usage and preserve the environment. In this paper, a mathematical technique is proposed ...to optimize water–wastewater networks, and a nonlinear program is introduced to minimize the consumption of freshwater and, consequently, the flowrate of wastewater discharge. A general mathematical model, able to handle industrial plants containing up to eight sources and eight sinks, is developed using LINGO optimization software to facilitate dealing with complex case studies. The introduced model can handle single-contaminant networks as well as multiple-contaminant ones. The optimal water network is synthesized through two steps; the first step involves the introduction of the case study data into the developed mathematical model. The second step considers using the optimal solution produced after running the developed LINGO model as feed data for a pre-designed Excel sheet able to deal with these results and simultaneously draw the optimal water–wastewater network. The proposed mathematical model is applied to two case studies. The first case study includes actual data from four fertilizer plants located in Egypt; the water resources and requirements are simultaneously integrated to obtain a sensible cutting in both freshwater consumption (lowered by 52.2%) and wastewater discharge (zero wastewater discharge). The second case study regards a Brazilian petrochemical plant; the obtained results show noticeable reductions in freshwater consumption by 12.3%, while the reduction percentage of wastewater discharge is 4.5%.
•Hydrotreating process is applied on the whole crude oil and not on its heavy products.•Correlations for sulfur, vanadium, nitrogen and nickel removal, are developed.•Influence of T, H2 PP, and LHSV, ...and their interactions on the hydrotreating process is studied.•An NLP algorithm is developed to find optimum operating conditions for hydrotreating processes.
In recent years, research has been directed towards upgrading of heavy crude oil as unconventional oil recovery rises. Catalytic hydrotreating of crude oil is an important upgrading option that is rarely discussed in literature. The main aim of crude oil hydrotreating is to reduce adverse environmental effects caused by the concentration of contaminants, increase productivity and improve the quality of middle distillate cuts. In this work, Response surface methodology (RSM) has been adopted to study the influence of various process parameters, such as hydrogen partial pressure, temperature and liquid hourly space velocity on the hydrotreating performance. The significance of these parameters is identified by using the analysis of variance (ANOVA) method. The resulting correlations are capable of predicting sulfur, vanadium, nitrogen and nickel conversions that are in excellent agreement with experimental data. The operating parameters are optimized with LINGO optimization software to achieve maximum conversions of contaminants during hydrotreating processes.
This research manifesto has a comprehensive discussion of the global dynamics of an achievable discrete-time two predators and one prey Lotka–Volterra model in three dimensions, i.e., in the space ...R3. In some assertive parametric circumstances, the discrete-time model has eight equilibrium points among which one is a special or unique positive equilibrium point. We have also investigated the local and global behavior of equilibrium points of an achievable three-dimensional discrete-time two predators and one prey Lotka–Volterra model. The conversion of a continuous-type model into its discrete counterpart model has been completed by adopting a dynamically consistent nonstandard difference scheme with the end goal that the equilibrium points are conserved in twin cases. The difficulty lies in how to find all fixed points O,P,Q,R,S,T,U,V and the Jacobian matrix and its characteristic polynomial at the unique positive fixed point. For that purpose, we use Mathematica software to find the equilibrium points and all of the Jacobian matrices at those equilibrium points. Moreover, we discuss boundedness conditions for every solution and prove the existence of a unique positive equilibrium point. We discuss the local stability of the obtained system about all of its equilibrium points. The discrete Lotka–Volterra model in three dimensions is given by system (3), where parameters α,β,γ,δ,ζ,η,μ,ε,υ,ρ,σ,ω∈R+ and initial conditions x0,y0,z0 are positive real numbers. Additionally, the rate of convergence of a solution that converges to a unique positive equilibrium point is discussed. To represent theoretical perceptions, some numerical debates are introduced, including phase portraits.
Water is the meaning of life for humans, agricultural and industrial processes; controlling the distribution of water and wastewater between industrial processes is very vital for rationalizing water ...and preserving the environment. This paper addresses a mathematical approach to optimizing water inter-plant networks. The water network problem is formulated as a nonlinear program (NLP) that is solved by LINGO Software, version 14.0. A generalized two-step mathematical model is designed to be valid for solving networks containing large numbers of sources and sinks. The introduced model is proposed to be used for both single and multiple contaminant problems with up to six contaminants. Two mathematical models are presented to design water inter-plant networks efficiently. Firstly, the introduced model is solved by LINGO, in which the data given are applied; the obtained results are simultaneously sent to a second model (based on Excel Software 2019, v. 16.0), by which the obtained water networks are automatically drawn. The proposed approach has been applied in three case studies; the first case study contains five plants of single contaminants, the second case study contains three plants of single contaminants, and the third case study contains three plants of multiple contaminants. The results showed a noticeable reduction in the percentages of freshwater consumption in the investigated three case studies, which were 38.6, 4.74 and 8.64%, respectively, and the wastewater discharge of the three case studies were decreased by 38.1, 4.61 and 8.65%, respectively.
Lead (Pb) is a biologically non-essential element in the soil that brutally affects plants and other living organisms in soil; hence, its removal has become a worldwide concern. In this work, a ...multifunctional nanoscale zerovalent-iron assisted biochar (nFe°/BC) was used to minimize the Pb bioavailability in soil with aim of alleviating the Pb-induced toxicity in sunflower. Results revealed that nFe°/BC treatment had significantly improved plant growth (58%), chlorophyll contents (66%), intracellular permeability (60%), and ratio factor (93%), while decreasing the Pb uptake (78%) in plants. The Pb-immobilization and transformation mechanisms were proposed, suggesting that the presence of organic functional groups over the nFe°/BC surface might induce the complex formation with Pb by the ions exchange process in soil solution. The XPS analysis confirmed that surface-active components (Fe
+
, O
2−
, O*, C═O) were the key factor for high Pb-immobilization within soil matrix. In addition, 87% of stable Pb species, including PbCO
3
, PbO, Pb (OH)
2
, and Pb-O-Fe were found in the soil surface. Current findings have exposed the diverse functions of nFe°/BC on plant health and established a phenomenon that nFe°/BC application could improve the plant agronomic attributes by regulating the homeostasis of antioxidants and Pb uptake.
It is known that the lack of controllability is the major cause of catastrophic events, energy inefficiency, and the generation of “off-spec” products to be treated as waste or to be recycled. This ...paper addresses the problem of synthesizing a mass exchanger network (MEN) that satisfies the control-related criteria “controllability”. In this work, four simple heuristic rules are introduced for MEN synthesis. Applying such simple rules in the matching step results in a highly controllable network, without requirement of sequential integration that would give rise to a time-consuming and tedious procedure requiring extensive iteration. Two alternative case studies are introduced to demonstrate the effectiveness of the proposed procedure.
