Optimum design of integrated liquid recovery plants by variable population size genetic algorithm

Increase in the price of energy sources as well as economic problems have caused cryogenic natural gas plants to become more complex and efficient. After selecting the process configuration, the flow rate, pressure, and temperature of the process fluid streams are determining factors which should be tuned in order to find the optimum condition. Products specification and operating costs of the plant are two significant parameters which should be considered in an optimal design. Moreover, process design limitations contribute to the problem being more difficult. This paper shows how the optimal operating point in an integrated NGL recovery plant can be found through solving a complex constrained optimization problem. A Variable Population size Genetic Algorithm (VPGA) was used for optimization. As well, the role of VPGA algorithm parameters in solving the process design problems is investigated in this study. The analysis showed that the VPGA method has better performance compared to the general GA methods. The plant‐wide net profit increases 12493360 $/year only by changing the selected operating conditions to its optimal value.     

Thermoeconomic optimization of a LiBr absorption refrigeration system

Optimization of thermal systems is generally based on thermodynamic analysis. Thermoeconomic optimization technique combines thermodynamic analysis with economic constraints to obtain an optimum configuration of a thermal system. In this study, the thermoeconomic optimization technique is applied to a LiBr absorption refrigeration system. Various components of the system such as condenser, evaporator, generator, and absorber heat exchangers are optimized. Additionally, optimum heat exchanger areas with corresponding optimum operating temperatures are determined. A cost function is specified for the optimum conditions. Finally, an example for the optimum design of a 20 kW LiBr system is given.     

Optimal operation of integrated processing systems: Part II: Closed-loop on-line optimizing control

A method for tracking the economically optimal operating conditions of a chemical process in the presence of constraints is developed. The technique is based on an on-line search rather than a fundamental model. The most profitable operating point is found by fitting a dynamic model of the process based on data obtained from experimental moves on the plant. This model is used to compute gradients of the economic objective and of the constraints so that a direction of economic improvement inside the allowed operating region of the plant is always obtained. Constraint violations during the transients are prevented by a multivariable regulator. A new regulation method (Internal Model Control) is used which permits explicit handling of constraints and which can be made robust against modelling errors. This combined optimization/regulation approach is tested in a demonstrative simulation example and shown to be reliable for following a moving optimum and safely handling complex constraint moves.     

气体分馏系统的节能降耗

针对气体分馏系统回流比偏大、操作压力偏高、压力波动大和分离纯度高、装置能耗居高、装置效益差等现状,利用石油化工流程模拟软件PRO/Ⅱ对气体分馏流程进行模拟计算.在满足产品质量要求(摩尔分数为99.5％)的前提下,探讨了压力、进料位置、回流比等参数对装置操作、能耗的影响,确定了丙烯损失的部位和原因,建立了装置操作的最佳工...     

Global optimality properties of total annualized and operating cost problems for compressor sequences

The minimum total annualized cost problem for a series of nonisentropic compressors and coolers that brings a gas with constant compressibility factor from a specified initial pressure and temperature to a specified final pressure and the same temperature is studied in this work. It is established analytically that at the global optimum, the cooler outlet temperatures are equal to the minimum allowable temperature. For constant heat capacity, constant compressibility factor gases, additional properties of the globally optimal compressor sequence are analytically established for the minimum operating cost case. The aforementioned properties permit development of a solution strategy that identifies the globally minimum operating cost. Several case studies are presented to illustrate the developed theorems and solution strategies. © 2014 American Institute of Chemical Engineers AIChE J 60: 4134–4149, 2014     

Prediction of economic operating conditions for Indian coal preparation plants

The most important optimization concept, which, has long been recognized in coal preparation with multiple cleaning circuits, is the constant incremental quality approach. However, this approach maximizes the overall plant yield for a targeted product quality, without putting any emphasis on coal value/price. So, sometimes confusion arises in the determination of the overall plant yield that would more than offset the price due to lower quality of product. In this paper a method is presented to maximize the coal value by considering the equal incremental quality approach as well. Here the predicted yield of composite coal has been calculated by using a designed probable error value, then the value of a particular coal is maximized. A case study with six different coals of different characteristics is presented to ascertain the merit of this approach. This technique offers the coal preparation engineer an effective and straight forward method for determining the optimum cut points of separation for different coals to achieve maximum economic gain.     

A mixed-integer formulation for back-off under constrained predictive control

The steady-state economic optimum in chemical process plants generally lies at the intersection of constraints. However, in order to maintain feasible operation in the face of disturbances, the steady-state operating point needs to be moved some distance from the constraints into the feasible region. The optimal back-off is a function of the plant dynamics, the type and magnitude of the expected disturbances, and the plant control system. This paper considers calculation of the optimal back-off with regulation under constrained predictive control. The resulting optimization problem is multilevel in nature, and is formulated and solved as a mixed-integer quadratic or linear programming problem for which global optimality is guaranteed. Case studies comprising CSTRs in series and a fluid catalytic cracking unit illustrate the application of the strategy.     

Environmental life cycle impact as a tool for process optimisation of a utility plant

The purpose of this paper is to minimize environmental life cycle impact when a detail process modelling is available. A methodology is presented to calculate the optimum operating conditions of an ethylene process utility plant. The overall environmental impact is calculated as a weighted sum of global warming, acidification, eutrophication, photochemical oxidation, ozone depletion, human toxicity and ecotoxicity. The battery limits of the plant are extended to include the relevant environmental impacts corresponding to the imported electricity generated in thermoelectric, hydroelectric and nuclear plants. A mixed integer non-linear programming problem is formulated and solved in GAMS. Significant reductions in environmental impact particularly in global warming, the most relevant category, are obtained choosing the pressure and temperature of high, medium and low pressure steam headers together with the selection of optional drivers and boilers. Improvements achieved simultaneously in natural gas and electricity consumption and operating cost are also reported.     

Computer-aided electrochemical process design: simulation and economic analysis of an electrocatalytic soybean oil hydrogenation plant

The process flowsheet for a soybean oil electrohydrogenation plant has been devised and heat and mass balance calculations on unit operations equipment were performed using a commercially available process simulation software package (PRO/II from Simulation Sciences, Inc.). The design and anticipated performance (current efficiency and power requirements) of the electrochemical flow cells were based on a laboratory-scale radial-flow-through Raney nickel powder electrocatalytic hydrogenation reactor. A semiempirical porous electrode model, that reproduced laboratory-scale reactor data, was incorporated into the PRO/II software as a unit operations subroutine module. Operation of a 3.0×106kgy–1 electrochemical plant was simulated on a computer for different soybean oil/electrolyte feeds and reactor current densities. Based on the PRO/II results, an economic analysis of the process, including capital, installation and operating costs of all equipment was carried out. The lowest total production cost for a brush hydrogenation oil product (20% reduction in the number of double bonds) was obtained at a current density of 15mAcm–2 and a feed composition of 10wt:vol% soybean oil in solvent/supporting electrolyte (US0.13kg–1 for an assumed five year straight line depreciation of capital equipment). This cost was higher than that for a comparable-size chemical catalytic soybean oil hydrogenation plant (US0.019kg–1). When the cost of the soybean oil starting material (US0.68kg–1) was factored into the economic analysis, the production plus raw material cost of the electrocatalytic process was only 16% greater than that for the chemical catalytic plant. The production cost for the electrosynthesized hydro-oil product may be tolerable because the oil has a high nutritional value (a lower trans isomers content) which may command a higher selling price.     

Economical Feasibility Evaluation of an Ethanol Injection Liposome Production Plant

Over the past few decades liposomes, which are lipid vesicles useful for the controlled release of numerous bioactive compounds, have attracted significant industrial interest. Several techniques have evolved for the manufacture of liposomes on a small scale. However, production on a commercially feasible scale is still somewhat limited. Therefore, this research intends to evaluate the scale‐up potential of a liposome production unit using the ethanol injection method, through preliminary economical feasibility estimation, as an addendum to a pre‐existing bioactive compound manufacture plant, with the aim of increasing the compound aggregate value. The ethanol injection technique is selected due to its simplicity and low cost, characteristics that make it easily scalable. The preliminary economic evaluation involves the assessment of capital investment, estimation of operating costs, and analysis of profitability. The results of the economic analysis suggest that the process is economically feasible for a plant with a daily production capacity of 288 L of liposomal suspension.     

顶装焦炉生产化工焦的试验研究

以顶装焦炉生产冶金焦炭的配煤比为基准,减少价格高的主焦煤的比例,增加气煤、贫瘦煤等价格较低的煤种,制定了多种生产化工焦的配煤比例,先在小焦炉试验找出最佳配比,然后在顶装焦炉进行试生产,取得了较好的效果。所生产的化工焦能满足公司甲醇厂造气炉的使用要求,替代了原使用的小块焦,降低了配煤成本及造气成本,提高了经济效益。     

全循环冷法复分解制取农用硫酸钾技术 ‘

烟台中兴化工有限公司自行研究开发的全循环冷法复分解制取农用硫酸钾工艺具有流程短、投资少、能耗低、腐蚀轻、无三废生产的特点。目前已经建成１万ｔ／ａ装置。经近几个月的连续运行表明,装置运行正常,产品质量稳定,原料利用率高,比热法复分解能耗低,操作费用少,经济效益可观。     

Alcoholic extraction of vegetable oils. V. Pilot plant extraction of cottonseed by aqueous ethanol

Summary Cottonseed flakes were extracted by aqueous ethanol in a countercurrent pilot plant unit to determine the effect of operating variables and the optimum operating conditions. This investigation has shown that direct extraction of cottonseed, using aqueous ethanol as a solvent, is a feasible process in the type of equipment developed previously in this laboratory. The optimum operating conditions for the ethanol extraction of cottonseed have been established. The pilot plant extractions have shown that in this process a prime quality of crude oil and lightcolored meal of good quality, with negligible free gossypol content, are obtained. Presented at the spring meeting, American Oil Chemists' Society, April 29-May 1, 1957, New Orleans, La.     

Analysis of water desalination and power generation expansion plans for the Emirate of Abu Dhabi — a preliminary study

This paper contains a comparative economic study of a number of different expansion schedules for power and desalination plants required to meet a forecasted demand in electricity and water for the Emirate of Abu Dhabi. For power generation, steam turbine and gas turbine plants were considered and for desalination both multistage flash distillation and reverse osmosis processes were investigated. Nine combinations of power and desalination plants were selected and a present worth economic analysis was conducted. Capital and operating cost figures used are those typical of the local conditions at Abu Dhabi. Based on the assumptions used in this study the plant combination using steam turbine power plant connected to a reverse osmosis unit seems to represent the most economic alternative.     

双气头多联产中醇醚燃料合成流程的经济评价

采用Aspen Icarus Process Evahator(Aspen IPE)软件对双气头多联产流程中关键工艺段--洁净气化煤气/焦炉煤气合成醇醚燃料单元进行了经济评价,以估算多联产系统中化工产品生产部分的经济性.经济评估计算以焦炭产能5 000 t/a的焦化厂为例,原料气按照气化煤气/焦炉煤气体积比1∶1进行输入,化学品合成工艺按一步法合成二甲醚(386 t/a),副产甲醇(242t/a).应用Aspen IPE软件计算该流程的投资费用、操作费用和利润率,并在此基础上分析了原料和产品价格变化对该项目经济性的影响.     

Applicability of flashing desalination technique for small scale needs using a novel integrated system coupled with nanofluid-based solar collector

The present study introduces an attempt for the application of flash desalination technique for small scale needs. An integrated system uses a flashing desalination technique coupled with nano-fluid-based solar collector as a heat source has been made to investigate both the effect of different operating modes and that of the variation of functioning parameters and weather conditions on the fresh water production. The flashing unit is performed by similar construction design technique of commercial multi-stage flashing (MSF) plant. The thermal properties of working fluid in the solar collector have been improved by using different concentrated nano-particles. Cu nano-particle is used in the modeling to determine the proper nano-fluid volume fraction that gives higher fresh water productivity. An economic analysis was conducted, since it affects the final cost of produced water, to determine the cost of fresh water production. Although a system may be technically very efficient, it may not be economical. The effect of different feed water and inlet cooling water temperatures on the system performance was studied. The mathematical model is developed to calculate the productivity of the system under different operating conditions. The proposed system gives a reasonable production of fresh water up to 7.7 l/m²/day under the operation conditions. Based on the cost of energy in Egypt, the estimated cost of the generated potable water was 11.68 US$/m³. The efficiency of the system is measured by the gained output ratio (GOR) with day time. The gained output ratio (GOR) of the system reaches 1.058. The current study showed that the solar water heater collecting area is considered a significant factor for reducing the water production cost. Also, the produced water costs decrease with increasing the collecting area of the solar water heater. The volume fractions of nano-particle in solar collector working fluid have a significant impact on increasing the fresh water production and decreasing cost.     

经济管径与工程投资浅析

分析了管道动力消耗与管径之间的函数关系及数学表达式，通过管道直径与管道单价的对应关系，阐述了管径与工程一次投资费用的关系。结果表明，管道直径与工程一次投资成正比而与动力消耗成反比，其间存在选取最佳管径，即经济管径的问题。最低综合费用=一次投资费用 操作费用。     

THE COMBINED EFFECT OF INCLINED ANGLE AND PLATE SPACING ON THE PERFORMANCES OF FLAT-PLATE THERMAL-DIFFUSION COLUMNS

When the separation is performed in a parallel-plate thermal diffusion column with the operating expense fixed, either increasing the plate spacing and operating at the corresponding optimum inclined angle, or increasing inclined angle and operating at the corresponding plate spacing, will increase the maximum separation and maximum production rate. Il was found that the cosine of optimum inclined angles increase with the plate spacing in the exponents of -9/2 and —4, respectively, for maximum separation and maximum production rate, while the optimum plate spacings increase with the cosine of inclined angle in the exponents of -2/9 and — 1/4, respectively. The plate spacing is generally so small that changing it, as well as changing the inclined angle, may not cause additional fixed change. However, increasing the plate spacing will lead to increasing the difference of plate temperatures in order to keep the operating expense, as well as the energy consumption due to heat conduction between the hot and cold plates, unchanged. Therefore, additional cost is needed to maintain a high value of temperature difference. There do not exist simultaneously the optimum inclined angle and the optimum plate spacing for the best performances.     

低油价下石油公司脱困路径浅析

国际油价自2014年6月遭遇"断崖式"下跌,至今仍在低位运行。较长时期的低油价对全球石油企业造成了持续性重创。国际国内石油公司通过采取降本减费、压缩投资、出售资产、削减产能、控制高风险项目等措施,实施低成本发展,以度过行业"寒冬"。中国石油公司还积极转变发展方式,调整结构,突出核心业务,依靠科技创新降低成本、创造新的经济增长点,借机推动产业升级,为今后转型发展积蓄能量。     

A laboratory centrifugal refining method for control application

A control method is presented for selecting the appropriate processing conditions for alkali refining of crude vegetable oils by the centrifugal process to yield lowest losses with satisfactory color. This technique is sufficiently analogous to actual processing conditions to provide reliable information upon which plant performance can be based. The cup method cannot be used in this manner in that it no longer approximates operating procedures as in the days of kettle refining. The chromatographic neutral oil method, on the other hand, provides an index of the amount of oil available for recovery without regard to the possibility of attaining such levels. For these reasons the centrifugal method fills a void of long standing. Other tangible benefits that accrue from this technique are: selection of sources of oil that can be most profitably refined by establishing the relative value of competitive oils, and a means of evaluating plant efficiency.