An economic receding horizon optimization approach for energy management in the chlor-alkali process with hybrid renewable energy generation

This paper presents a methodology for the application of receding horizon optimization techniques to the problem of optimally managing the energy flows in the chlor-alkali process using a hybrid renewable energy system (HRES). The HRES consists of solar and wind energy generation units and fuel cells to supply energy. The HRES is also connected to the grid and allows for buying or selling electricity from and to the grid. Initially, detailed models of each system component are introduced as the basis for the simulation study. Energy management strategies are then developed to realize the objectives of meeting production requirements while minimizing the overall operating and environmental costs. Sensitivity and uncertainty analyses are carried out to elucidate the key parameters that influence the energy management strategies. Finally, production demand response is integrated into the proposed methodology.     

用混合式遗传算法进行给水管网现状分析

将广义简约梯度法(GRG)思想应用于传统遗传算法,提出一种新的混合式遗传算法(HGA),此方法具有很强的全局和局部搜索能力,并且无需复杂的编码、解码过程,可以准确解决多变量、多峰值的给水管网现状分析问题。采用此算法,绝大多数的计算值与实测值的误差可减小到1%以下,能准确反映管网的实际工况。     

Conceptual design of a novel hybrid fuel cell/desalination system

A novel concept for integrating fuel cells with desalination systems is proposed and investigated in this work. Two unique case studies are discussed — the first involving a hybrid system with a reverse osmosis (RO) unit and the second — integrating with a thermal desalination process such as multi-stage flash (MSF). The underlying motivation for this system integration is that the exhaust gas from a hybrid power plant (fuel cell/turbine system) contains considerable amount of thermal energy, which may be utilized for desalination units. This exhaust heat can be suitably used for preheating the feed in desalination processes such as reverse osmosis which not only increases the potable water production, but also decreases the relative energy consumption by approximately 8% when there is an increase of just 8°C rise in temperature. Additionally, an attractive hybrid system application which combines power generation at 70%+ system efficiency with efficient waste heat utilization is thermal desalination. In this work, it is shown that the system efficiency can be raised appreciably when a high-temperature fuel cell co-generates DC power in-situ with waste heat suitable for MSF. Results indicate that such hybrid system could show a 5.6% increase in global efficiency. Such combined hybrid systems have overall system efficiencies (second-law base) exceeding those of either fuel-cell power plants or traditional desalination plants.     

Dynamic Mechanical Properties and Adhesive Strengths of Emulsion Polymer by Power Feed Technique, I

Dynamic mechanical properties and adhesive strengths of power feed copolymer and random copolymer synthesized using styrene or methyl methacrylate and n-butyl acrylate were investigated. Although the two systems were synthesized from the same raw materials, power feed copolymer had a very broad transition compared with random copolymer. This fact was explained by the fact that the system synthesized through power feed method was an alloy of copolymers which are a continuous series from monomer A rich copolymers to monomer B rich copolymers. The dynamic mechanical behavior of film cast from solution was almost the same as that of emulsion film, which indicated more extensive application of power feed copolymer. In the P(nBA/St) system, power feed copolymer maintained its adhesive strengths over a wide temperature range compared with random copolymer. The absolute value, however, was not so high. This was due to the low cohesive strengths of the films.     

Hybrid systems in seawater desalination—practical design aspects, present status and development perspectives

Ever since seawater desalination has been applied on an industrial scale, and particular in the countries of the Arabian Gulf, the application of desalination processes in dual-purpose facilities—water and power—as a hybrid configuration has been discussed in many feasibility investigations and also planning concepts. It is above all the combination of reverse osmosis with thermal processes that has found increasing interest with the aim of ensuring, as economically as possible, uniform water supplies under the specific, greatly varying load conditions in the Gulf countries. Such design concepts for hybrid configurations encompass straightforward structures with a low degree of coupling between membrane and thermal desalination processes, but range up to very complex configurations with strong interconnections on both the water side and thermally, as well as with several desalination processes connected in series or in parallel. Classical hybrid concepts in which the permeate from an RO desalination component is mixed with distillate from thermal desalination have already been implemented in Saudi Arabian dual-purpose plants, like Jeddah and Yanbu-Medina. Although hybrid systems of greater complexity have been addressed in many design studies and publications, up to now none has been brought to fruition. Coming into consideration asthe design basis for determining the capacity shares of the various desalination processes operated in a hybrid configuration are: arrangement of thermal cycle of the power plant component; water/power ratio of the dual-purpose seawater desalination and power plant; provision of undiminished water production of the desalination plant as electricity generation varies; provision of a specified drinking water quality with regard to composition and salt content; combination of all these aspects. Also gaining in importance are concerns of environmental pollution and sustainable development when selecting seawater desalination and power plant configurations, as well as their optimization when considering desalination and electricity generation as a whole. In the practical design of hybrid membrane and thermal systems, aspects come to light, though, that restrict linking of the two systems and joint utilization of facilities, as conceived in studies and conceptual design investigations. This applies both for common utilization of intakes and the use of heated up cooling water from thermal processes as a feed stream for the RO part of the desalination process. Additionally, requirements of drinking water composition, particularly chloride content, TDS and compliance with a specific residual content of boron, influence specifically the design of the membrane process part and its share in the total desalination capacity. Such practical aspects have greatly influenced the design and configuration of the Fujairah hybrid plant for which, from a total desalination capacity of 100 MIGD (454,600 m³/d), the share of 37.5 MIGD (170,500 m³/d) makes its seawater RO plant the biggest currently being constructed anywhere in the world. From the findings of the engineering of this plant and the idea that, by increasing interconnection between the two processes on the water side, it is possible to advance a hybrid configuration of this type with regard to cost optimization in the membrane installation, but also by joint utilization of the intake equipment, perspectives result for applied research efforts over the near and long terms, for example: long-term behavior of membranes at elevated temperatures; tendency for biofouling in membrane process with common utilization of cooling water and brine; influences of such interconnections on the overall availability of the facility. But also for the operation and maintenance organization of such large facilities, consequences can be foreseen for the future development of hybrid plants, particularly for operation management and organisation of the interplay of the different power plant and desalination systems, monitoring of SWRO membrane replacement and cleaning, as well as controlling water quality.     

核壳型乳液聚合研究进展

综述了近年来核/壳结构聚合物乳液的聚合工艺、性能及核/壳结构的表征方法进行,讨论了影响核/壳结构聚合物乳胶粒子形态的各种因素。     

Residual strength of hybrid-fiber-reinforced high-strength concrete after exposure to high temperatures

Residual strengths of high-strength concrete (HSC) and hybrid-fiber-reinforced high-strength concrete (HFRHSC) after exposure to high temperatures were investigated in the paper. The results showed that normal HSC is prone to spalling after exposure to high temperatures, and its first spalling occurs when the temperature approaches 400 °C. For HSC reinforced by high melting point fibers, the first spalling occurs when the temperature reaches to approximately 800 °C, while there is no spalling during exposing to high temperatures for HSC reinforced by polypropylene (PP) fiber with a low melting point. Mixing high melting point fiber (i.e., carbon or steel fiber) with low melting point fiber (i.e., PP fiber) HSC greatly improves the properties of HSC after exposure to high temperatures.     

Hybrid materials based on metal oxides and poly(organophosphazenes)

In this paper the sol-gel preparation of hybrid materials made of metal oxide and polytorganophosphazenel components is described. The main problem focused on during this research was to avoid phase separation in order to get homogeneous materials. This problem was pursued looking at the formation of genuine chemical bonds between the exploited polyphosphazenes and the inorganic composite networks. Investigations on the thermal, mechanical, and electroconductive properties of the synthesized, phosphazene-containing composite materials showed that these matrices presented improved mechanical and thermal features with respect to those of the original phosphazene macromolecule, while the ionic conductivities of the prepared molecular hybrids doped with lithium or silver trillate are of the same order of magnitude as those measured for the neat, original phosphazene substrate.Presented at the Ist Italian Workshop on Cyclo- and Polytphosphazenel Materials. February 15–16, 1996. at the CNR Research Area in Padova, Italy.     

Conductive hybrid film from polyaniline and polyurethane-silica

In order to improve the mechanical performance and water resistance of water-borne conducting polyaniline film, conducting polyaniline/polyurethane-silica hybrid film was prepared in aqueous solution employing silanol-terminated polyurethane and methyltriethoxysilane as sol-gel precursors. The hybrid film showed surface resistivity of 10⁸ Ω even though the conducting polyaniline loading was only 10 wt% (or 1.5 wt% of polyaniline), and the mechanical performance as well as water resistance was significantly improved, making it suitable for antistatic application. Therefore, a practical route to water-borne processing of conducting polyaniline is disclosed.     

New results on PWARX model identification based on clustering approach

This paper deals with the problem of piecewise auto regressive systems with exogenous input(PWARX) model identification based on clustering solution. This problem involves both the estimation of the parameters of the affine sub-models and the hyper planes defining the partitions of the state-input regression. The existing identification methods present three main drawbacks which limit its effectiveness. First, most of them may converge to local minima in the case of poor initializations because they are based on the optimization using nonlinear criteria. Second, they use simple and ineffective techniques to remove outliers. Third, most of them assume that the number of sub-models is known a priori. To overcome these drawbacks, we suggest the use of the density-based spatial clustering of applications with noise(DBSCAN) algorithm. The results presented in this paper illustrate the performance of our methods in comparison with the existing approach. An application of the developed approach to an olive oil esterification reactor is also proposed in order to validate the simulation results.