scholarly journals Optimal Design of a Two-Stage Membrane System for Hydrogen Separation in Refining Processes

Processes ◽  
2018 ◽  
Vol 6 (11) ◽  
pp. 208 ◽  
Author(s):  
Ana Arias ◽  
Patricia Mores ◽  
Nicolás Scenna ◽  
José Caballero ◽  
Sergio Mussati ◽  
...  
Keyword(s):  
Annual Cost ◽  
Optimal Solution ◽  
Membrane System ◽  
Operating Conditions ◽  
Total Annual Cost ◽  
Membrane Area ◽  
Expansion Turbine ◽  
Process System ◽  
H2 Recovery ◽  
Process System Engineering

This paper fits into the process system engineering field by addressing the optimization of a two-stage membrane system for H2 separation in refinery processes. To this end, a nonlinear mathematical programming (NLP) model is developed to simultaneously optimize the size of each membrane stage (membrane area, heat transfer area, and installed power for compressors and vacuum pumps) and operating conditions (flow rates, pressures, temperatures, and compositions) to achieve desired target levels of H2 product purity and H2 recovery at a minimum total annual cost. Optimal configuration and process design are obtained from a model which embeds different operating modes and process configurations. For instance, the following candidate ways to create the driving force across the membrane are embedded: (a) compression of both feed and/or permeate streams, or (b) vacuum application in permeate streams, or (c) a combination of (a) and (b). In addition, the potential selection of an expansion turbine to recover energy from the retentate stream (energy recovery system) is also embedded. For a H2 product purity of 0.90 and H2 recovery of 90%, a minimum total annual cost of 1.764 M$·year−1 was obtained for treating 100 kmol·h−1 with 0.18, 0.16, 0.62, and 0.04 mole fraction of H2, CO, N2, CO2, respectively. The optimal solution selected a combination of compression and vacuum to create the driving force and removed the expansion turbine. Afterwards, this optimal solution was compared in terms of costs, process-unit sizes, and operating conditions to the following two sub-optimal solutions: (i) no vacuum in permeate stream is applied, and (ii) the expansion turbine is included into the process. The comparison showed that the latter (ii) has the highest total annual cost (TAC) value, which is around 7% higher than the former (i) and 24% higher than the found optimal solution. Finally, a sensitivity analysis to investigate the influence of the desired H2 product purity and H2 recovery is presented. Opposite cost-based trade-offs between total membrane area and total electric power were observed with the variations of these two model parameters. This paper contributes a valuable decision-support tool in the process system engineering field for designing, simulating, and optimizing membrane-based systems for H2 separation in a particular industrial case; and the presented optimization results provide useful guidelines to assist in selecting the optimal configuration and operating mode.

scholarly journals Membrane-Based Processes: Optimization of Hydrogen Separation by Minimization of Power, Membrane Area, and Cost

Processes ◽  
2018 ◽  
Vol 6 (11) ◽  
pp. 221 ◽  
Author(s):  
Patricia Mores ◽  
Ana Arias ◽  
Nicolás Scenna ◽  
José Caballero ◽  
Sergio Mussati ◽  
...  
Keyword(s):  
Cost Minimization ◽  
Initial Guess ◽  
Total Power ◽  
Total Annual Cost ◽  
Membrane Area ◽  
Trade Offs ◽  
Processing Plants ◽  
Cost Minimization Problem ◽  
H2 Recovery ◽  
Total Membrane

This work deals with the optimization of two-stage membrane systems for H2 separation from off-gases in hydrocarbons processing plants to simultaneously attain high values of both H2 recovery and H2 product purity. First, for a given H2 recovery level of 90%, optimizations of the total annual cost (TAC) are performed for desired H2 product purity values ranging between 0.90 and 0.95 mole fraction. One of the results showed that the contribution of the operating expenditures is more significant than the contribution of the annualized capital expenditures (approximately 62% and 38%, respectively). In addition, it was found that the optimal trade-offs existing between process variables (such as total membrane area and total electric power) depend on the specified H2 product purity level. Second, the minimization of the total power demand and the minimization of the total membrane area were performed for H2 recovery of 90% and H2 product purity of 0.90. The TAC values obtained in the first and second cases increased by 19.9% and 4.9%, respectively, with respect to that obtained by cost minimization. Finally, by analyzing and comparing the three optimal solutions, a strategy to systematically and rationally provide ‘good’ lower and upper bounds for model variables and initial guess values to solve the cost minimization problem by means of global optimization algorithms is proposed, which can be straightforward applied to other processes.

scholarly journals Inventory Models for Non-Instantaneous Deteriorating Items with Expiration Dates and Imperfect Quality under Hybrid Payment Policy in the Three-Level Supply Chain

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1695
Author(s):  
Jui-Jung Liao ◽  
Hari Srivastava ◽  
Kun-Jen Chung ◽  
Shih-Fang Lee ◽  
Kuo-Nan Huang ◽  
...  
Keyword(s):  
Supply Chain ◽  
Cost Function ◽  
Annual Cost ◽  
Optimal Solution ◽  
Inventory Model ◽  
Deteriorating Items ◽  
Total Annual Cost ◽  
Chain Model ◽  
Object Function ◽  
Supply Chain Model

This article considers an inventory model for non-instantaneous deteriorating items with expiration dates, such as seasonal items, first-hand vegetables, and fruits. Interestingly, an inspection will be performed to manage the quality of the items during the state of no deterioration because it is difficult to purchase items with 100% perfection. Additionally, we assume that the upstream member has the power of controlling or influencing downstream members’ decisions. That is, the supplier asks the retailer for a partial advance payment to avoid cancellation of orders and offers them a credit payment to stimulate sales; in turn, the customer must pay some cash when placing an order and pay the remainder in credit for the retailer. The goal of this article is to determine an optimal replenishment cycle and the total annual cost function, so we explore the functional properties of the total annual cost function and show that the total annual cost function is convex. Theoretical analysis of the optimal properties shows the existence and uniqueness of the optimal solution. Then, we obtain simple and easy solution procedures for the inventory system. Moreover, numerical analysis of the inventory model is conducted, and the corresponding examples are considered with a view to illustrating the application of the supply chain model that we have investigated in this article. Finally, in the concluding section, we have not only provided the motivation and the need for our usages of mathematical analytic solution procedures based upon the convexity, monotonicity (increasing and decreasing) and differentiability properties of the object function (that is, the total annual cost function), which involve some symmetry aspects of the object function, but we have also indicated the limitations and shortcomings in our investigation, which will naturally lead to some potential directions for further research on the supply chain model, which we have considered and mathematically analyzed in this article.

scholarly journals The effect of service constraint on EPQ model with random defective rate

2006 ◽  
Vol 2006 ◽  
pp. 1-5 ◽  
Author(s):  
Yung-Fu Huang
Keyword(s):  
Annual Cost ◽  
Differential Calculus ◽  
Cost Minimization ◽  
Algebraic Approach ◽  
Optimal Solution ◽  
Service Level ◽  
Economic Production Quantity ◽  
Economic Production ◽  
Epq Model ◽  
Production Quantity

Chiu studied the effect of service-level constraint on the economic production quantity (EPQ) model with random defective rate. In this note, we will offer a simple algebraic approach to replace his differential calculus skill to find the optimal solution under the expected annual cost minimization.

Process system engineering in biodiesel production: A review

2013 ◽  
Vol 22 ◽  
pp. 631-639 ◽  
Author(s):  
N.F. Nasir ◽  
W.R.W. Daud ◽  
S.K. Kamarudin ◽  
Z. Yaakob
Keyword(s):  
System Engineering ◽  
Biodiesel Production ◽  
Process System ◽  
Process System Engineering

scholarly journals Integration of Operability Framework and Pareto Optimal Front to Calculate Optimal Condition of Ethane Cracking Process

2020 ◽  
pp. 105-113
Author(s):  
M. Farsi
Keyword(s):  
Pareto Front ◽  
Optimal Solution ◽  
Optimization Procedure ◽  
Operating Conditions ◽  
Base Case ◽  
Pareto Optimal ◽  
Multi Objective Optimization ◽  
Pareto Optimal Front ◽  
Multi Objective ◽  
Cracking Process

The main aim of this research is to present an optimization procedure based on the integration of operability framework and multi-objective optimization concepts to find the single optimal solution of processes. In this regard, the Desired Pareto Index is defined as the ratio of desired Pareto front to the Pareto optimal front as a quantitative criterion to analyze the performance of chemical processes. The Desired Pareto Front is defined as a part of the Pareto front that all outputs are improved compared to the conventional operating condition. To prove the efficiency of proposed optimization method, the operating conditions of ethane cracking process is optimized as a base case. The ethylene and methane production rates are selected as the objectives in the formulated multi-objective optimization problem. Based on the simulation results, applying the obtained operating conditions by the proposed optimization procedure on the ethane cracking process improve ethylene production by about 3% compared to the conventional condition.  

scholarly journals Determining the causes, prevention and elimination of unstable modes of gas turbochargers of marine diesels

2021 ◽  
Vol 27 (1) ◽  
pp. 33-51
Author(s):  
Володимир Миколайович Калугін ◽  
Олександр Міхайлович Мунтян
Keyword(s):  
Waste Heat ◽  
Operating Experience ◽  
Optimal Solution ◽  
Operating Conditions ◽  
Heat Recovery Boiler ◽  
Effective Functioning ◽  
Contractual Arrangements ◽  
Safe Level ◽  
Air Supply ◽  
Trial Test

Annotation – With commissioning of the “Socofl Star” ship’s series, negative occurrences relative to surging of the Main Engine (ME) «Hanshin Diesel» 6LF46 turbochargers (TC) VTR 401-2. To elimination of a surging, it was necessary reduce loading of ME to the safe level. This action caused the ship’s speed to fall from 11 – 10 to 4 knots which resulted in worsening of the ship’s maneuverability characteristics and lead to the failure to provide the ship’s service speed stipulated in the contractual arrangements. Existence of this problem instigated the shipowner to charge us as experts with the mission of carrying out appropriate investigations and working out recommendations as to how to prevent and eliminate surging of TC. This task was solved on the m/v “Socofl Star”. Based on results the ME shop test and trial test of the vessel and also the saved-up data of work of ME in various conditions of swimming, the analysis of the causes of a surge of the TC was made. It is established that small values of safety factor of stability of the compressor of TC on a surging – KCT which are not allowing to ensure effective functioning of TC on the main modes of loading of ME are its reason. For increase in area of steady work of TC it is necessary to reduce the hydraulic resistance of components of the Air-Gas Path (AGP) of the ME which can be realized by changes in a design of units of air supply and gas exchange or reduction of productivity and extent of increase in pressure of air in the compressor of TC. Under operating conditions vessels an optimal solution an objective is removal of a part of blowing-off air after compressor of the TC. The air can be discharged into the flue gas header after the waste heat recovery boiler or directly into the atmosphere. This allowed the shipowner not to make constructive changes to the components of the AGP of ME and TC. The description of the operated unloading device controlled remotely on removal of air which ensures effective functioning of TC and ME that is confirmed by results of natural tests and the subsequent operating experience of vessels of the “Socofl Star” series is provided.

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