水力旋流器能耗机制与节能原理研究 Ⅷ.优化节能原则

研究了水力旋流器的节能与强化分离性能的匹配优化。结果表明,旋流器能耗的降减与分离性能的强化具有一致性,于是提出了兼顾节能与强化分离性能的优化节能原则;研究了能耗系数与运行费用准数之间的关系,表明最低运行费用准数并非对应最小能量耗损,并探讨了流场结构对运行费用准数的影响规律;系统地给出了旋流器在以不同工艺指标为目标函数时的优化结构组合基础数据库,为在不同工艺场合下运行的旋流器的优化节能提供出设计指导     

基于经济学观点确定换热网络传热温差

从分析和经济学的角度提出了确定换热网络最小传热温差的方法。在基于夹点技术温焓图的基础上,把冷、热公用工程物流的基本属性同工艺物流的组合曲线一起标示于温焓图上,组成平衡组合曲线。对平衡冷、热组合曲线进行分段积分,较精确地求取换热网络传热过程的损失。以损费用代替公用工程的能耗费用作为操作费用,确定经济目标函数,用以计算最佳的传热温差。该方法为合理地降低能源消耗指明了方向,同时揭示了能量在过程系统中演变和变化的本质。     

Exergoeconomic Analysis of Heat Exchanger Networks for Optimum Minimum Approach Temperature

Heat exchanger networks (HENs) design for optimum minimum approach temperature is presented using exergoeconomic analysis. Cold and hot utilities are integrated with process streams into T‐H plots, forming balanced composite curves, based on pinch technology. Exergy consumption of heat transfer in HENs is calculated using subsection integral on balanced composite curves. Exergy consumption expense substitutes utilities cost as operating cost. The objective function based on exergoeconomics is proposed, which determines the optimum minimum approach temperature of HENs. Numerical results in the cases demonstrate the validity of the proposed approach. Some measures of decreasing energy consumption are disclosed in the dealing process as well.     

Techno-economic evaluation of top,middle, and bottom divided wall column configurations for benzene,toluene, and xylene processing in aromatic production plant

Divided wall column (DWC) configurations were simulated and optimized for five different feed’s compositions to demonstrate the effect of feed composition and location of dividing wall in DWC in optimum operating conditions, energy requirement, operating, capital and total annualized cost (TAC) to produce market-grade benzene, toluene, and xylene. Operating conditions and cost for each DWC strongly depend on feed composition. Middle DWC (M-DWC) requires significantly lower energy compared with top and bottom DWCs except for feed dominated with xylene where energy requirement is comparable in studied configurations and M-DWC seems the best for ternary mixture separation.     

氨氮废水生化处理探讨

概述了化肥行业氨氮废水的危害 ,根据生物降解处理的动力学研究实验得到的生化处理的最佳操作条件 ,进行了生化处理方案的比较 ,介绍了采用改良氧化沟处理氨氮废水工艺流程及处理效果 ,指出了氨氮废水生化处理降低运行成本的研究方向     

基于持续节能的多周期换热网络优化设计

在石油化工工业中,换热网络的操作条件时常发生改变,尤其是结垢热阻随运行时间不断增大。针对操作条件的改变,有研究者提出多周期换热网络最优综合的设计与改造方法。但是,这些方法不涉及结垢热阻对设计结果的影响。然而,换热器结垢不可避免,传热系数随之改变,将导致操作工况偏离最优值,难以实现持续节能优化。以多周期换热网络优化为基础,提出一种基于持续节能的多周期换热网络综合设计方法,以换热网络累积总费用为目标函数,考虑换热器结垢对多周期换热网络优化结果的影响,进而实现多周期换热网络的最优综合。首先,结合示例分析换热器结垢对多周期换热网络优化结果的影响,得出考虑到结垢热阻的影响多周期换热网络在各个周期内的优化结果将改变;然后,基于持续节能优化,以换热网络累积总费用为目标函数,提出一种多周期换热网络优化方法;最后,结合示例验证了该设计方法的有效性。     

Multi-Response Optimization of Parameters for the Electrocoagulation Treatment of Electroplating Wash-Water using Aluminum Electrodes

This present study investigates Ni and Mg removal from electroplating wash-water employing electrocoagulation with aluminum electrodes. The simultaneous effects of various operating parameters were evaluated and optimized using a central composite design in terms of Ni, Mg removal, COD removal, energy consumption, and operating cost. At these optimum conditions (current density = 86.23 A/m², pH = 7.5, operating time = 60 min, and NaCl dose = 0.5 g/l), 97% Ni removal and 90% Mg removal was achieved with energy consumption of 22.45 kWh per kg Ni removed and operating cost being 4 $ per kg Ni removed. X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis were on the residue obtained.     

Treatment of potato chips manufacturing wastewater by electrocoagulation

Treatment of wastewater from potato chips manufacturing by electrocoagulation (EC) was investigated. Experiments were conducted to determine the optimum operating conditions such as electrode type, pH, current density and retention time. Aluminium and iron electrodes were used, and aluminium electrodes were found to be more suitable since it had a higher removal rate of COD, turbidity and suspended solids than the iron electrode. The removal efficiencies of COD and turbidity were high, being 60% and 98%, respectively, with retention time < 40 min. 0.05–1.75 kg (per kg COD removed) of dried sludge was removed. COD removal kinetics during EC process was described by a macro-kinetics model. Results from the kinetic studies showed that the kinetic data fit the second-order kinetic model well. The operating costs investigated in the present study were the energy cost of EC and the material cost due to the consumption of aluminium electrode. Operating costs were varied in the range of 0.48 to 5.42 $/m³ and 0.62 to 6.32 $/m³ wastewater treated at 20–300 A/m² and 5–40 min, respectively. The energy consumption was 4 kWh/m³ for wastewater treated less than 8 min under typical operating conditions.     

Iterative approach to the study of optimal production policies for a multipurpose plant

A study of optimum operating conditions for operation of a multi-purpose nitrating plant is carried out by means of a decomposition technique. The plant is multipurpose inasmuch as three products—nitrobenzene, monotrichlorobenzene, nitrotoluene—can be produced with the same configuration of equipment. The decomposition procedure is applied to the analysis of the optimum structure of the plant and the economic environment, which identifies two sub-systems, namely the plant and inventory model. The technique facilitates the solution of the system, while preserving the dimensionality.

An economic global index of performance is taken as the present value, which can be optimised in terms of production rates, running times and number of runs for each individual process. For a particular set of market conditions a global optimum is defined and its sensitivity to some of the costs is assessed. It is found that, although the value of the index is sensitive to the level of unit manufacturing cost and unit selling price, the location of the optimum, and consequently the optimum operating strategy, remains unchanged for changes up to 5% in unit cost and price.     

Synthesis of Rice Processing Plants. II. MINLP Optimization

A systematic design approach was applied to develop the optimal process flowsheet for a rice processing plant. The optimization problem was formulated as a Mixed-Integer NonLinear Programme, MINLP, consisting of vectors of binary and continuous variables. A superstructure flowsheet comprising all serial structures of drying, cooling, and tempering units in the process was postulated. The set of optimum decision variables including the number of drying, cooling, and tempering units, temperature and relative humidity of drying air, drying time, cooling time, and tempering time were determine as the solution of the corresponding MINLP. Six objective functions were investigated as possible performance criteria: production time, number of the operating units, energy consumption, total operating cost, head rice yield, and the profit. The choice of objective function was found to have a significant effect on the optimal solution. Comparison with typical design and operating conditions, the MINLP results showed that a 22% reduction in energy consumption was possible along with a 2.4% increase in head rice yield. These savings, if applied to the world-wide rice industry, translate into more than $3 billion dollars/year increase in profit.     

Modeling and economic analysis of CO<Subscript>2</Subscript> separation process with hollow fiber membrane modules

The main purpose of the study was to develop a model using ASPEN and Excel simulation method to establish optimum CO₂ separation process utilizing hollow fiber membrane modules to treat exhaust gas from LNG combustion. During the simulation, optimum conditions of each CO₂ separation scenario were determined while operating parameters of CO₂ separation process were varied. The characteristics of hollow fibers membrane were assigned as 60 GPU of permeability and 25 of selectivity for the simulation. The simulation results illustrated that 4 stage connection of membrane module is required in order to achieve over 99% of CO₂ purity and 90% of recovery rate. The resulted optimum design and operation parameters throughout the simulation were also correlated with the experimental data from the actual CO₂ separation facility which has a capacity of 1,000 Nm³/day located in the Korea Research Institute of Chemical Technology. Throughout the simulation, the operating parameters of minimum energy consumption were evaluated. Economic analysis of pilot scale of CO₂ separation plant was done with the comparison of energy cost of CO₂ recovery and equipment cost of the plant based on the simulation model. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Treatment of paint manufacturing wastewater by electrocoagulation

Treatability of paint manufacturing wastewater (PMW) by electrocoagulation (EC) process was investigated. Effects of operating parameters for the EC process such as electrode type (Al or Fe), initial pH (2–10), current density (5–80 A/m²) and operating time (0–50 min) were evaluated for optimum operating conditions. The highest removal efficiencies for COD and TOC in PMW were obtained with 93% and 88% for Fe and 94% and 89% for Al electrodes at the optimum conditions (35 A/m², 15 min and pH 6.95). Operating costs for removal of PMW at the optimum conditions were calculated for Fe and Al electrodes as 0.187 €/m³ and 0.129 €/m³. Toxicity test was carried out to obtain information about toxic effect of the raw and treated wastewaters at optimum operating conditions. The samples measured by respirometric method contained hardly toxicities. Performance of Al electrode was better than that of Fe electrode in terms of removal efficiency and operating cost.     

Computer code for optimizing MSF desalination plant

Egypt faces the prospect of population growth pressing on available agricultural land resources. A very large areas of coastal desert could be helpful in population density redistribution and of great economical interest, with the installation of a suitable water supply.Of the many desalination processes, the Multi-Stage Flash (MSF) desalination process is still the most developed and reliable technology for large scale conversion of sea water to fresh water.In this paper, a computer code was developed for optimizing a large scale MSF plant. This code can calculate the optimum design for the plant, and the minimum cost of product fresh water, as a function of both design and operating variables.Sample results obtained using this code for the Egyptian conditions are presented. The effect of energy and material costs, the chemical treatment type, and the feed water salinity on the optimum performance ratio and the minimum fresh water cost are drawn.     

催化裂化吸收稳定系统低温节能工艺开发初探

以某炼油厂催化裂化吸收稳定系统工艺数据作为模拟和计算的基础,从单因素和双因素角度研究了循环汽油温度及平衡罐温度对吸收稳定系统物流及能耗的影响,为后续低温节能工艺开发提供了依据。研究结果表明,随着循环汽油温度由40℃逐步降至5℃,平衡罐气液相及循环汽油质量流率下降,系统能耗下降约16%。系列循环汽油温度下,随着平衡罐温度的上升,系统能耗均呈现正U形曲线趋势,在35~55℃范围内出现系列最低点,即该循环汽油温度下系统能耗最优点。随着循环汽油温度的降低系统能耗逐渐减小。因此,除了考察适用的最优操作温度外,还需综合评估工艺匹配的节能设备投资及操作费用,才能开发经济性最优的吸收稳定系统低温节能工艺。     

The energetic and/or economic optimisation or heterogeneous reactors

The first part of this paper presents the bases for the technico-economic optimisation of reactors.The optimum design of a reactor is by minimising an objective function which, depending on the choice of the decision-maker and for a given production rate, could be :- the cost in the national currency- the cost in foreign exchange- the consumption of primary energy- the consumption of exergy.In addition the decision-maker could in each case also aim to minimise :- the cost of equipment (investment)- the operating cost- the total cost, that is the weighted sum of the capital equipment cost and the operating cost for a chosen period of amortizement.These various optima are compared one with another, notably those which minimise money cost and those which minimise the consumption of primary energy. It is shown that between each there exist invariant ratios : for each optimum the contribution of each of the terms (equipment, operating…) to the total cost is a constant and is independent of economic factors. It is only a function of technical factors such as the flow regime (laminar or turbulent) transport process (diffusion, convection…).In the part two, the general concepts developped in part one are applied to the design of heterogeneous catalytic reactors (with fixed, fluidised or transported particles).A “simplissime” model is proposed which depends on only one parameter representing the hydrodynamic structure of the flow in the reactor. This model includes various types of flow structure : short circuit, recycle, total or partial macro-mixing, anisotropic jet hitting the active surface, etc… A general expression is established for the “Specific Operating Consumption of Mechanical Energy” (or SOCME) in joules per kg of useful product. The way the SOCME varies with the process parameters, especially the Reynolds number is examined for the main operating regimes of the reactor.- Volume effect regime : transport by convection - macro-mixing - short circuiting.- Surface effect regime : heterogeneous chemical reaction or transport by diffusion through the boundary layer.Operating conditions for which the limitation due to diffusion in the boundary layer is negligible are defined for the general case of any reactor.Illustration is given of how to apply these concepts to the optimisation of a fixed bed reactor where the requirement is to simultaneously :- maximise the productivity- minimise the energy consumption- minimise the construction cost of the reactor.Thus in any optimized reactor, the consumption of mechanical operating energy is a non-negligible fraction of the total optimisable expenditure (from 10 to 30 %) and this is valid even and especially in the chemical reaction regime. It may be concluded that in the future, reactors which will be required to consume less and less energy, should no longer be designed to operate in the chemical reaction regime but should be allowed to have certain physical rate limitations whether diffusional or convective.     

Optimization and adaptive control of a semi-batch synthesis reactor

The optimization of a chemical synthesis aims at an adjustment of the operating conditions, i.e. pH, temperature and initial concentrations, in order to obtain maximum yield, minimum operating costs or similar. The optimization effort may be considerable so that, in many cases, its cost cannot be justified, especially for small volume products. This paper introduces a new strategy, namely to establish the optimum operating conditions with a relatively small effort. The new approach is illustrated by the synthesis of 2-furyl oxirane. In the first step, a simplified mechanistic process model has to be determined on the basis of easily accessible experimental data. Initial and final concentrations of all reacting components, reaction time and temperature must be known. A two-step evaluation yields the stoichiometric coefficients of all the occurring reactions as well as the parameters of the Arrhenius model. This so-called trend model is used in the optimization of the operating conditions. It is not only important to know the optimum operating conditions but also to maintain them as close as possible in practical operation. An adaptive controller is well suited to such an application and its use is discussed.     

Design optimisation of an air-oil heat exchanger

A procedure for determining the maximum performance over cost ratio, and the corresponding fin dimensions and operating conditions in the design of a plate finned air-oil heat exchanger is presented. The method assumes a particular material, manufacture and energy cost structure as well as certain practical limitations. It is found that the performance cost ratio is most significantly influenced by the number of operational hours per annum. Generally the optimum fin tends to be thinner with a larger effective diameter, while the air and oil velocities are lower than those found in industrial applications. These lower velocities require the optimum heat exchanger to be larger and thus more costly initially. An industrial oil cooler is tested experimentally in order to verify the accuracy of the heat transfer and pressure drop equations employed and for purposes of comparison.     

仓式泵气力输送系统优化设计

通过对仓式泵输送装置运行参数测试和分析,发现在某一输送条件下其能耗最小。利用优化设计方法,可以找出仓式泵系统能耗最省的最佳操作条件。最后介绍了优化设计应用实例。     

Design Optimization of a Crude Oil Distillation Process

In this work, the optimal design of a crude oil distillation unit was made. Since the method used here is based on the general optimization framework, it is possible to design the process systematically. The results of this study gave better performances than that of the existing process. The process in this study is currently in operation and has the capacity of 150,000 BPSD. Feed locations, heat duties of pumparounds and operating conditions of the preheat train are selected as variables, and the energy consumption, operating cost and annual cost are formulated as objective functions. The optimal feed locations of both the main column and stabilizer are obtained by solving rigorous models and mixed integer nonlinear programming. Considering the results of the optimal feed tray, the cost optimization is carried over to obtain the optimal annual cost, which considers both the capital and operating cost, which is decreased from US$10,649,000/year to USdollar;9,185,230/year.     

降膜结晶法精制对苯二甲酸二甲酯的研究

对苯二甲酸二甲酯 (DMT)是生产聚酯的基本原料 ,由于精制工艺流程长 ,导致DMT成本高 ,降低了竞争力。本文将降膜结晶技术用于DMT的分离精制 ,得到了高纯度的产品 ,讨论了各种操作条件对结晶速度和产品纯度的影响 ,确定了最优操作条件