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1.
A strategy for water and wastewater minimization is developed for continuous water utilization systems involving fixed flowrate(non-mass-transfer-based)operations,based on the fictitious operations that is introduced to represent the water losing and/or generating operations and a modified concentration interval analysis(MCIA) technique.This strategy is a simple,nongraphical,and noniterative procedure and is suitable for the quick yields of targets and the identification of pinch point location.Moreover,on the basis of the target method,a heuristic-based approach is also presented to generate water utilization networks,which could be demonstrated to be optimum ones. The proposed approaches are illustrated with example problems.  相似文献   

2.
In this paper we address the topic of energy and water optimization in the production of bioethanol from corn and switchgrass. We show that in order for these manufacturing processes to be attractive, there is a need to go beyond traditional heat integration and water recycling techniques. Thus, we propose a strategy based on mathematical programming techniques to model and optimize the structure of the processes, and perform heat integration including the use of multi-effect distillation columns and integrated water networks to show that the energy efficiency and water consumption in bioethanol plants can be significantly improved. Specifically, under some circumstances energy can even be produced and the water consumption can be reduced below the values required for the production of gasoline.  相似文献   

3.
基于参数估计的动态系统过失误差侦破与识别   总被引:1,自引:0,他引:1       下载免费PDF全文
The detection and identification of gross errors, especially measurement bias, plays a vital role in data reconciliation for nonlinear dynamic systems. Although parameter estimation method has been proved to be a powerful tool for bias identification, without a reliable and efficient bias detection strategy, the method is limited in efficiency and cannot be applied widely. In this paper, a new bias detection strategy is constructed to detect the presence of measurement bias and its occurrence time. With the help of this strategy, the number of parameters to be estimated is greatly reduced, and sequential detections and iterations are also avoided. In addition, the number of decision variables of the optimization model is reduced, through which the influence of the parameters estimated is reduced. By incorporating the strategy into the parameter estimation model, a new methodology named IPEBD (Improved Parameter Estimation method with Bias Detection strategy) is constructed. Simulation studies on a continuous stirred tank reactor (CSTR) and the Tennessee Eastman (TE) problem show that IPEBD is efficient for eliminating random errors, measurement biases and outliers contained in dynamic process data.  相似文献   

4.
This study presents the first demonstration project in China for treatment of coal-bed methane(CBM) co-produced water and recycling.The work aims to provide a research and innovation base for solving the pollution problem of CBM extraction water.The reverse osmosis(RO) unit is applied to the treatment of CBM co-produced water.The results indicate that system operation is stable,the removal efficiency of the total dissolved solids(TDS) is as high as 97.98%,and Fe,Mn,and F-are almost completely removed.There is no suspended solids(SS) detected in the treated water.Furthermore,a model for the RO membrane separation process is developed to describe the quantitative relationship between key physical quantities-membrane length,flow velocity,salt concentration,driving pressure and water recovery rate,and the water recovery restriction equation based on mass balance is developed.This model provides a theoretical support for the RO system design and optimization.The TDS in the CBM co-produced water are removed to meet the "drinking water standards" and "groundwater quality standards" of China and can be used as drinking water,irrigation water,and livestock watering.In addition,the cost for treatment of CBM co-produced water is assessed,and the RO technology is an efficient and cost-effective treatment method to remove pollutants.  相似文献   

5.
The scarcity of water, mainly in arid and semiarid areas of the world is exerting exceptional pressure on sources and necessitates offering satisfactory water for human and different uses. Water recycle/reuse has confirmed to be successful and promising in reliable water delivery. For that reason, attention is being paid to the effective treatment of alternative resources of water (other than fresh water) which includes seawater, storm water, wastewater (e.g., dealt with sewage water), and industrial wastewater. Carbon nanotubes (CNTs) are called the technology of 21st century. Nowadays CNTs have been widely used for adsorption of heavy metals from water/ wastewater due to their unique physical and chemical properties. This paper reviews some recent progress (from 2013 to 2018) in the application of CNTs for the adsorption of heavy metals in order to remove toxic pollutants from contaminated water. CNTs are expected to be a promising adsorbent in the future because of its high adsorption potential in comparison to many traditional adsorbents.  相似文献   

6.
This article deals with the design of energy efficient water utilization systems allowing operation split. Practical features such as operating flexibility and capital cost have made the number of sub operations an important parameter of the problem. By treating the direct and indirect heat transfers separately, target freshwater and energy consumption as well as the operation split conditions are first obtained. Subsequently, a mixed integer non-linear programming (MINLP) model is established for the design of water network and the heat exchanger network (HEN). The proposed systematic approach is limited to a single contaminant. Example from literature is used to illustrate the applicability of the approach.  相似文献   

7.
It is believed that whether the instantaneous objective function curves of plug-flow-reactor (PFR) and continuous-stirred-tank-reactor (CSTR) overlap or not, they have a consistent changing trend for complex reactions(steady state, isothermal and constant volume). As a result of the relation of the objective functions (selectivity or yield) to the instantaneous objective functions (instantaneous selectivity or instantaneous reaction rate), the optimal reactor network configuration can be determined according to the changing trend of the instantaneous objective function curves. Further, a recent partition strategy for the reactor network synthesis based on the instantaneous objective function characteristic curves is proposed by extending the attainable region partition strategy from the concentration space to the instantaneous objective function-unreacted fraction of key reactant space. In this paper,the instantaneous objective function is closed to be the instantaneous selectivity and several samples axe examined to illustrate the proposed method. The comparison with the previous work indicates it is a very convenient and practical systematic tool of the reactor network synthesis and seems also promising for overcoming the dimension limit of the attainable region partition strategy in the concentration space.  相似文献   

8.
The Korea Atomic Energy Research Institute (KAERI) launched a nuclear hydrogen program to develop and demonstrate a hydrogen mass production system by 2019. The key feature of the system is to produce the hydrogen from water using nuclear power. No fossil fuel (energy) will be used and no greenhouse gas will be emitted. The high temperature gas-cooled reactor (HTGR), which has high safety characteristics with competitive economy, is being developed to provide a high temperature heat (about 1000℃) required to produce hydrogen from water. A decision will be made on the reactor specifications after the pre-conceptual design works. Both thermo-chemical process and high temperature electrolysis are to he used for the production of hydrogen from water using nuclear heat. The production of hydrogen from water by nuclear power is one of the most viable options for the mass production of the hydrogen using non-fossil fuels. In 2020s, the nuclear based hydrogen is planned to provide about 20% of total energy consumed in the transportation of Korea. The nuclear hydrogen is expected to make a considerable contribution to the national energy security of Korea.  相似文献   

9.
通过流股的合理合并改进用水网络的能量效率   总被引:2,自引:0,他引:2  
Water-using operations in the process industry have demands for water usually both on water quality and temperature, and the existing mathematical models of heat exchange networks cannot guarantee the energy performance of a water network optimal. In this paper, the effects of non-isothermal merging on energy performance of water allocation networks are analyzed, which include utility consumption, total heat exchange load, and number of heat exchange matches. Three principles are proposed to express the effects of non-isothermal merging on energy performance of water allocation networks. A rule of non-isothermal merging without increasing utility consumption is deduced. And an approach to improve energy performance of water allocation network is presented. A case study is given to demonstrate the method.  相似文献   

10.
吸附分离CH4/N2可行性研究   总被引:10,自引:0,他引:10       下载免费PDF全文
The separation between methane and nitrogen is an inevitable and important task in the C1 chemical technology and the utilization of methane from coalbed, yet it is considered to be one of the tough tasks in the field of separation. Pressure swing adsorption is a preferable technology if an adsorbent that allowing a large coefficient of separation for the CH4/N2 system is available. The separation coefficients between CH4 and N2 were obtained on analyzing the breakthrough curves measured experimentally with nine adsorbents. A technique of measuring the temperature-pulse was incorporated in the experiments, and the reliability of the result was improved. Superactivated carbon with large surface area and plenty of micropores was shown to have the largest separation coefficient and to be promising for the commercial utilization.  相似文献   

11.
吸附分离CH4/N2可行性研究   总被引:2,自引:0,他引:2       下载免费PDF全文
The separation between methane and nitrogen is an inevitable and important task in the C1 chemical technology and the utilization of methane from coalbed, yet it is considered to be one of the tough tasks in the field of separation. Pressure swing adsorption is a preferable technology if an adsorbent that allowing a large coefficient of separation for the CH4/N2 system is available. The separation coefficients between CH4 and N2 were obtained on analyzing the breakthrough curves measured experimentally with nine adsorbents. A technique of measuring the temperature-pulse was incorporated in the experiments, and the reliability of the result was improved.Superactivated carbon with large surface area and plenty of micropores was shown to have the largest separation coefficient and to be promising for the commercial utilization.  相似文献   

12.
For high-purity distillation processes, it is difficult to achieve a good direct product quality control using traditional pro-portional-integral-differential (PID) control or multivariable predictive control technique due to some difficulties, such as long re-sponse time, many un-measurable disturbances, and the reliability and precision issues of product quality soft-sensors. In this paper, based on the first principle analysis and dynamic simulation of a distillation process, a new predictive control scheme is proposed by using the split ratio of distillate flow rate to that of bottoms as an essential controlled variable. Correspondingly, a new strategy with integrated control and on-line optimization is developed, which consists of model predictive control of the split ratio, surrogate model based on radial basis function neural network for optimization, and modified differential evolution optimization algorithm. With the strategy, the process achieves its steady state quickly, so more profit can be obtained. The proposed strategy has been successfully applied to a gas separation plant for more than three years, which shows that the strategy is feasible and effective.  相似文献   

13.
Both reverse osmosis (RO) and nanofiltration (NF) membranes have been increasingly used for water purification and desalination. However, the salt rejection of NF membranes is quite different from that of RO membranes, which makes a significant distinction in their process designs. This work started from the performance investigation of a single NF membrane element and then focused on the process design of the NF system for surface water treat-ment. In experimental tests, it was found that the observed rejection of the NF element becomes nearly constant when the concentrate flow is large enough, while the membrane flux of the NF element is quite stable regardless of the water flow across the membrane surface. These findings can be used to instruct the process design of the NF system for surface water treatment. In process design, a two-stage arrangement is sufficient for the NF system to reach the highest water recovery, while the RO system requires a three-stage arrangement.  相似文献   

14.
While conventional wastewater treatments for urban effluents are fairly routine and have proved highly effective,industrial wastewater requires more complex and specific treatments.This paper provides a technological strategy for removal of recalcitrant contaminants based on a hybrid treatment system.The model effluent containing a binary mixture of synthetic dyes is treated by a combination of a preliminary physicochemical stage followed by a biological stage based on ligninolytic enzymes produced by Phanerochaete chrysosporium.This proposal includes biosorption onto peat as pretreatment,which decreases the volume and concentration to be treated in the biological reactor,thereby obtaining a completely decolorized effluent.The treated wastewater can therefore be reused in the dyeing baths with the consequent saving of water resources.  相似文献   

15.
Poly(N-isopropylacrylamide)(PNIPAAm) grafted onto silica,which may be used for reverse phase chromatography(RPC),was simulated and synthesized for protein separation with temperature-triggered adsorption and desorption.Molecular dynamics simulation at an all-atom level was performed to illustrate the adsorption/desorption behavior of cytochrome c,the model protein,on PNIPAAm-grafted-silica,a temperature responsive adsorbent.At a temperature above the lower critical solution temperature(LCST),the PNIPAAm chains aggregate on the silica surface,forming a hydrophobic surface that is favorable for the hydrophobic adsorption of cytochrome c,which has a high exposure of hydrophobic patches.At temperatures below the LCST,the PNIPAAm chains stretch,forming hydrophilic surface due to hydrogen bonding between PNIPAAm and surrounding water.Desorption of cytochrome c on the PNIPAAm-grafted-silica surface occurs as a result of competition with water,which forms hydrogen bonds with the protein.The conformational transitions of both cytochrome c and PNIPAAm are monitored,providing molecular insight into this temperature-responsive RPC technique.PNIPAAm-grafted-silica beads were synthesized and used for the adsorption and desorption of cytochrome c at approximately 313 K and 290 K,respectively.The experimental results validate the molecular dynamics simulation.In comparison to conventional RPC,using temperature as a driving force for RPC reduces the risk of protein denaturation caused by exposure to chaotropic solvents.Moreover,it simplifies the separation process by avoiding the buffer exchange operations between the steps.  相似文献   

16.
Semiconductor fabrication is a manufacturing sequence with hundreds of sophisticated unit operations and it is always challenged by strategy development for ensuring the yield of defect-free products. In this paper, an advanced control strategy through integrating product and process control is established. The proposed multiscale scheme contains three layers for coordinated equipment control, process control and product quality control. In the upper layer, online control performance assessment is applied to reduce the quality variation and maximize the overall product performance (OPP). It serves as supervisory control to update the recipe of the process controller in the middle layer. The process controller is designed as an exponentially weighted moving average (EWMA) run-to-run controller to reject disturbances, such as process shift, drift and tool worn out, that are exerted to the op-eration. The equipment in the process is individually controlled to maintain its optimal operational status and maximize the overall equipment effectiveness (OEE), based on the set point given by the process controller. The ef-ficacy of the proposed integrated control scheme is demonstrated through case studies, where both the OPP (for product) and the OEE (for equipment) are enhanced.  相似文献   

17.
不确定条件下炼化企业计划与调度整合策略   总被引:2,自引:1,他引:2       下载免费PDF全文
A strategy for the integration of production planning and scheduling in refineries is proposed.This strategy relies on rolling horizon strategy and a two-level decomposition strategy.This strategy involves an upper level multiperiod mixed integer linear programming(MILP) model and a lower level simulation system,which is extended from our previous framework for short-term scheduling problems [Luo,C.P.,Rong,G.,"Hierarchical approach for short-term scheduling in refineries",Ind.Eng.Chem.Res.,46,3656-3668(2007)].The main purpose of this extended framework is to reduce the number of variables and the size of the optimization model and,to quickly find the optimal solution for the integrated planning/scheduling problem in refineries.Uncertainties are also considered in this article.An integrated robust optimization approach is introduced to cope with uncertain parameters with both continuous and discrete probability distribution.  相似文献   

18.
Distillation column control is widely explored in literature due to its complexity and importance in chemical and petrochemical industries.In this process,pressure represents one of the most important variables to be controlled.However,there are few studies about how pressure affects the dynamic behavior of distillation columns and most research on distillation column control involve direct manipulation of cooling fluid through the condenser.Nevertheless,such an approach demands constant changes in cooling fluid flowrates that are commonly by the order of tons per hour,which can be difficult to work or even unfeasible in a real plant.Furthermore,this strategy is usually avoided,as it can cause fouling and corrosion acceleration.The hot-vapor bypass strategy fits well as a solution for these issues,eliminating the need to dynamically manipulate cooling fluid flowrates in the condensation unit.This work presents the modeling and simulation of a conventional distillation column for the separation of water and ethanol,in which a comparative study between a conventional pressure control and a control using hot-vapor bypass was performed.The main results were obtained through dynamic simulations which considered various disturbances in the feed stream,and demonstrated superior performance by the hot-vapor bypass system over the usual scheme proposed in literature,while evaluating the Integral Absolute Error (IAE) norm as the control performance index.  相似文献   

19.
过程工业中具有能量集成的用水网络优化设计   总被引:5,自引:0,他引:5  
Effective utilization of water and energy is the key factor of sustainable development in process industries, and also an important science and technology problem to be solved in systems engineering. In this paper,two new methods of optimal design of water utilization network with energy integration in process industries are presented, that is, stepwise and simultaneous optimization methods. They are suitable for both single contaminant and multi-contaminant systems, and the integration of energy can be carried out in the whole process system, not only limited in water network, so that energy can be utilized effectively. The two methods are illustrated by case study.  相似文献   

20.
For those refineries which have to deal with different types of crude oil, blending is an attractive solution to obtain a quality feedstock. In this paper, a novel scheduling strategy is proposed for a practical crude oil blending process. The objective is to keep the property of feedstock, mainly described by the true boiling point (TBP) data, consistent and suitable. Firstly, the mathematical model is established. Then, a heuristically initialized hybrid iterative (HIHI) algorithm based on a two-level optimization structure, in which tabu search (TS) and differential evolution (DE) are used for upper-level and lower-level optimization, respectively, is proposed to get the model solution. Finally, the effectiveness and efficiency of the scheduling strategy is validated via real data from a certain refinery.  相似文献   

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