Development of Decision Support System for Optimal Site Selection of Desalination Plants

Transcription

1 IOSR Journal of Mechancal and Cvl Engneerng (IOSR-JMCE) e-issn: ,p-ISSN: X, Volume 11, Issue Ver. III (Nov- Dec. 014), PP Development of Decson Support System for Optmal Ste Selecton of Desalnaton Plants 1 Muhsen S. Alhrar, Khary Agha, 3 Samah k. Alghoul 1 The Hgher Insttute of Industral Technology-Engla Trpol - Lbya Renewable Energy Authorty of Lbya (REAoL)Trpol - Lbya 3 Power Dvson, Mechancal and Industral Engneerng DepartmentUnversty of Trpol, Trpol - Lbya Abstract:In ths paper, Decson Support System (DSS)for ste selecton of seawater desalnaton plant has beendeveloped. The general methodology ncludes two man steps for ste selecton. The frst steps togenerate a lst of possble locatons dependng on the crteron of mnmzng water transportaton cost. Ths s establshed by usng non-lnear objectve functon.in the second step, the locaton s optmzed usng Multcrtera analyss(mca) takng nto account mportant factors affectng the optmzaton process.each factor s gven a weght accordng to ts mportance from one to eght. As a case study,the developed DSS s appled on coastal ctes of northwest of Lbya. Those ctes located between Ras-EJdarand Musrata.Sample results are shown n ths paper n order to explan the developed DSS. Keywords:Decson Support System, Mult-crtera analyss,desalnaton, Lbya, Ste Selecton. I. Introducton The ncreasng concern of governments and publc to meet ther multple water demands wthn lmted budgets made the search for alternatve water demands nevtable. Desalnaton s becomng more effectve alternatve for water scarcty worldwde. In Lbya, desalnaton becomes more cost compettve as ground water transported from the south needs to be pumped from lower levels whch ncreases ts prce[1]. In addton, extracton of ground water from the south of Lbya to cover the requred water demand of the northern ctes s recently proved to have serous envronmental ssues on the southern area of Lbya[]. The nstallaton of a desalnaton faclty represents a hgh captal cost nvestment. Therefore, the optmal selecton and sttng of these facltes s crtcal. Ste selecton of a desalnaton plant s one of the most mportant decsons n plannng a seawater desalnaton project. Ths decson affects the project captal and runnng cost, the project performance and possbly the project schedule. Ste selecton ssue s not only a challenge related to desalnaton plants but also t consdered a vtal decson that mght affect many other ndustres. There are two general approaches to ste selecton, the numercal approach and the comparatve approach. Usually a combnaton of the two approaches s requred to come up wth the ste locaton fnal decson. Fgure 1 shows the approaches used n ste selecton and some of ther man aspects. The current approach to ste selecton of any desalnaton faclty must take nto account, n addton to engneerng economc factors, a numerous of non-techncal factors. Fgure 1: Ste selecton approaches. The man objectve of ths study s to develop a robust decson support system to defne optmum locatons of desalnaton plants accordng to objectve functon and mult-crtera analyss under a varety of mportant constrants. The Lbyan coast can be consdered as three separate enttes, the northwest area, the mddle north area, and the northeast area. The northwest area extends from Ras-Ejdar to Musrata and ncludes the ctes ofras- 84 Page

2 Development of Decson Support System for Desalnaton Plants Optmal Ste Selecton Ejdar, Zoltun, Zwara, Subrata, Surman, Zawa, Trpol, Qaraboul, Khomus, Zlten and Msurata. The mddle north area extends from Musrata to Ejdabaand ncludes the ctes of Towerga, Esdada, Seret, Benjawad, Elsdera and Ejdaba. The northeast area extends from Ejdaba to Assalum and ncludes the ctes of Benghaz, Shahat, Derna, Sosa, Tubruk and Assalum. The northern west coast of Lbya s consdered as a case study n ths paper wherenon-lnear equaton of second degree s appled n frst step to determne canddate locatons for desalnaton plants.in the secondstep, the mult-crtera analyss s appled on the canddate locatons n order to dentfy best locatons for seawater desalnaton plant. II. The Methodology In ths study, the analytcal models wll be combned wth tradtonal related dataand ncluded n a computer program n order to obtanoptmum ste selecton of desalnaton plants. These steps can be descrbed as Decson Support System (DSS) that stradtonally used to support managements and plannng levels of busness and organzatonsn decson-makng. Fgure shows the flow chart of the decson support system for ste selecton of seawater desalnaton plant proposed n ths study. The Decson Support System s developed n ths paperfocuses on two mportant steps that summarze the methodology of the optmzaton. These two steps are solvng the objectve functon to mnmze the water transportaton coast and dentfy canddate locatons then applyng mult-crtera analyss on all those locatons n order to obtan best alternatve locaton(s). Fgure :Block dagram of the Decson Support System (DSS) for Desalnaton Ste Selecton 1.1 Desalnaton Plant Ste Selecton Methodsappled n ste selecton problems offer consderable potental for applcaton of analytcal approaches n operatons research. These methods can be utlzed to fnd a plant locaton amongst a varety of possble locatons that s consdered the best soluton accordng to certan crtera. The new plant can be consdered as ether a pont locaton or an area locaton dependng on the faclty type. Faclty locaton problems can be categorzed nto sx elements: new faclty characterstcs, exstng faclty locatons, new and exstng faclty nteractons, soluton space characterstcs, dstance measure, and the objectve. In the present study, the faclty s consdered as a pont locaton, and the new faclty characterstc s capacty. Assumng there are no desalnaton plants n the area of study, the exstng faclty locatonas well as new and exstng faclty nteracton elements can be gnored. The soluton space characterstcs and dstance measures are determned through the prevalng geographc data avalable. In general, the objectve s to fnd the followng quantty[3]. n mn Q L F,a Page

3 Where Q F a L F, a Development of Decson Support System for Desalnaton Plants Optmal Ste Selecton = The water demand for cty [m 3 /day] = The locaton of the desalnaton plant = The locaton of cty = The absolute shortest dstance between the desalnaton plant and cty Ths quantty shown above presents the best locaton, from water transportaton pont of vew, for a certan combnaton of ctes. The soluton of the above equaton for all possble combnaton of ctes s vtal n decdng about ctes that must be covered by a certan desalnaton plant. 1. Mult-crtera Evaluaton Methods There are varous classfcatons of mult-crtera evaluaton methods: dscrete multple crtera methods versus contnuous multple objectve methods, and hard nformaton methods versus soft nformaton methods. Dscrete methods only dsplay a fnte number of feasble choce possbltes, whle contnuous methods may encompass an nfnte number of choce possbltes. Hard nformaton means nformaton measured on a cardnal scale, whereas soft nformaton means nformaton based on a qualtatve scale. In ths study, one of the dscrete mult-crtera cardnal methods,know as weghted summaton [4], s used to provde a bass for classfyng a number of alternatve possbltes based on multple crtera. Ths method has been chosen because t can handle a large number of objectves and stll provde acceptable representaton of decson maker s preference. In addton, the weghted method transforms the mult-objectve problem nto a sngle optmzaton problem for whch soluton method exst. Ths method often uses two knds of nput data, an evaluaton matrx and a set of poltcal weghts attached to the crteron scores that s ncluded n the evaluaton matrx. For the selecton of the locaton where the amount of transferred water s mnmum, several alternatves have been studed. These alternatves nclude the establshment of a separate plant for each cty and plants coverng the demand of several ctes. Ths choce s as follows: In the frst step of the selecton, we determne the best locaton for the transfer of water usng equaton 1. The second step s to subject the serousness of the selected locatons of the frst step to multcrtera test so evdent mpact of external factors on the locaton chosen. These factors ncludng near water source, water qualty, near consumers, etc. III. Data Collecton Durng the course of ths work, a comprehensve data collecton on each cty and each potental ste were conducted by revewng the avalable studes and reports publshed by the Natonal Water Authorty of Lbyaand others[5]. In addton to the water demand, the datacollected nclude among others, the geographcal and envronmental nformaton, the dstances between ctesand electrc power generaton facltes. By mplementng the ratng prncple, each parameter was rated accordng to the data collected by assgnng a value of eght for the parameter that has perfect condtons for a partcular ste. Ths procedure was adapted from a prevous study carred out for North Afrca [4]. The north-west coast of Lbya contans manly eleven ctes startng from Ras-Eljdar at the far west (on the border of Tunsa) and endng at Musrata (n the mddle of Lbya). Table 1 shows those ctes where each cty have been assgned an dentfcaton number.the water demand for each cty and the progressve dstance startng from Ras-Ejdar are also shown n the table.fgure 3 shows the ctes n the north-west coast of Lbya. Table 1: Cty Id Number and respectve water demand[5-7] Cty Id Dstance from Water Ras-Ejdar (km) (m 3 /day) Ras-Eljdar Zoltun Zwara Subrata Surman Zawa Trpol Qaraboul Khomus Zlten Musrata Demand 8 Page

4 Development of Decson Support System for Desalnaton Plants Optmal Ste Selecton Lbya Fgure 3:shows the ctes of the North West coast IV. Generaton of possble combnatons For the selecton of the best locaton, allpossble combnaton of the ctes have been scheduled n table. Those combnatons nclude the establshment of a separate desalnaton plant for every cty (alternatve number 5 to ), one plant for all ctes (alternatve number 10) and desgnatng a plant coverng the demand of some ctes (alternatve number 1 to 9 and 11 to 55). Table : The ctes satsfed by the solutons and ts dstance to the proposed plant locaton. No. Ctes Satsfed Dstance to the Proposed Plant (km) 1 1, 1,4 1,, 3 5,5,15 3 1,, 3, 4 49,9,9,41 4 1,, 3, 4, 5 8,48,8,,3 5 1,, 3, 4, 5, 8,8,4,4,14,34 1,, 3, 4, 5,, 7 14,1,10,5,4,,14 7 1,, 3, 4, 5,, 7, 8 148,18,108,58,48,8,1,7 8 1,, 3, 4, 5,, 7, 8, 9 155,135,115,5, 55,35,5,5,15 9 1,, 3, 4, 5,, 7, 8, 9, 10 1,14,1,7,,4,,58,118, ,, 3, 4, 5,, 7, 8, 9, 10, ,155,135,85,75,55,15,45,105,145,185 11, 3 9,11 1, 3, 4 34,14,3 13, 3, 4, 5 51,31,19,9 14, 3, 4, 5, 9,49,1,11,31 15, 3, 4, 5,, 7 17,107,57,47,7,13 1, 3, 4, 5,, 7, 8 19,109,59,49,11,71 17, 3, 4, 5,, 7, 8, 9 13,11,5,55,35,5,5,15 18, 3, 4, 5,, 7, 8, 9, ,13,73,3,43,3,57,117,157 19, 3, 4, 5,, 7, 8, 9, 10, 11 15,13,8,7,5,1,44104,144, , 4 0,30 1 3, 4, 5 45,5,15 3, 4, 5, 59,9,1,1 3 3, 4, 5,, 7 110,0,50,30,10 4 3, 4, 5,, 7, 8 11,,5,3,8,8 5 3, 4, 5,, 7, 8, 9 119,9,59,41,1,59,119 3, 4, 5,, 7, 8, 9, 10 1,7,,48,8,5,11,15 7 3, 4, 5,, 7, 8, 9, 10, ,89,79,59,19,41,101,141, , 5,4 9 4, 5, 17,7, , 5,, 7 3,53,33,7 31 4, 5,, 7, 8 4,54,34,, 3 4, 5,, 7, 8, 9 71,1,41,1,59, , 5,, 7, 8, 9, 10 78,8,48,8,5,111, , 5,, 7, 8, 9, 10, 11 9,8,,,38,98,138, , 1,8 3 5,, 7 54,34, 37 5,, 7, 8 5,3,4,4 38 5,, 7, 8, 9 3,43,3,57, ,, 7, 8, 9, 10 70,50,10,50,110, ,, 7, 8, 9, 10, 11 84,4,4,3,99,139,179 41, 7 37,3 87 Page

5 Development of Decson Support System for Desalnaton Plants Optmal Ste Selecton 4, 7, 8 39,1,1 43, 7, 8, 9 4,,54,114 44, 7, 8, 9, 10 53,13,47,107,147 45, 7, 8, 9, 10, 11 58,18,4,10,14,18 4 7, 8, , 8, 9 9,51, , 8, 9, 10 17,43,103, , 8, 9, 10, 11 3,8,88,18, , 9 39,1 51 8, 9, 10 1,1,39 5 8, 9, 10, 11 91,31,9, , 10 19,1 54 9, 10, 11 4,, , 11 5, V. Results and Dscusson In the frst step mentoned before,equaton 1s appled on the possbltes shown n Table,thebest locaton for the desalnaton plant s determned for every alternatve. The thrd column n table shows the dstances between the ctes of consderaton and the best-chosen locaton of the desalnaton plant, where demand of dfferent ctes affect the calculated best locaton. Alternatve number two s studed n detals n order to llustrate the decson support system developed n ths work. Alternatvenumber two ncludes the three ctes of Ras-Eljdar (Id 1), Zoltun(Id ) and Zwara (Id 3). Fgure 4 shows the results obtaned by usng equaton 1 along the dstance between the three ctes. The curve represents the objectve functons at dfferent locatons. It s clear from the curve that the mnmum pont of the objectve functon occurs n a pont between the selected ctes. However, for any other alternatve the suggested locaton should be found n some pont n between or on the border ctes for the selected alternatve. When the objectve functon s appled on alternatve numberthe mnmum value of the objectve functon found to be between the ctes of Zoltun and Zwara. The suggested locaton by the frst step s at place of5 km from Ras-Eljdar and t s tooclose to the cty of Zoltun due to the hgh water demand at ths cty. Ths locaton s also shown on Fgure 5. Fgure 4:Desalnaton plant ste selecton for alternatve number 1 accordng to equaton Page

6 Development of Decson Support System for Desalnaton Plants Optmal Ste Selecton Fgure 5: Desalnaton plant ste selecton for alternatve number accordng to equaton 1. The second step s to subject the selected locatons obtaned from the frst step to mult-crtera tests. Table 3 shows the canddate locatons for the ste selecton for alternatve number two. Four locatons are suggested n ths work. The locatons are the three ctes (1,, 3) and the suggested locaton obtaned by the objectve functon whch s about 5 km from cty 1. Table 3 shows that for ths alternatve the category scores are equal for most crteron such as exstng sources of water products, vcnty electrcty sources, product water sellng prce, regulatons and land avalablty. The man parameter that affects the total score s the qualty of seawater. The suggested locaton (last column) s easer to access and presents the best water qualty between the four places. Overall the forth locaton has a hgher score than the other locatons (the three ncluded ctes n ths alternatve). Table 3: Relatve weght for each cty n the North West area accordng to each crtera(mca appled on alternatve number ) Cty d number Weght per sngle Suggested Maker crtera category crteron 1 3 locaton % weght % Ratng Ratng Ratng Ratng Raw water proxmty Raw water qualty Exstng source of product supply product water dstrbuton net work proxmty of consumers ntegraton n ndustral network vcnty power plants/electrcal 15 network product water sellng prce energy cost manpower cost fnancal parameters local regulaton and applcable 10 standard skll of labor/contractor land avalablty Access Total Page

7 Development of Decson Support System for Desalnaton Plants Optmal Ste Selecton Fnally, all possbltes shown n table 1 should be subjected to the same Multcrtera analyss n order to conclude the fnal locatons. VI. Summary and Conclusons In ths paper a Decson Support System for seawater desalnaton plant ctng and szng s developed. The system conssts of two man steps: applyng the objectve functon to mnmze water transportaton costs and then applyng Multcrtera analyss to select the best locatons. Based on the analyss along wth the case study and results and dssuason presented n ths paper, the followng conclusons can be drawn; frst, the work provdes a sutable tool for the decson makers concernng the optmum locaton of desalnaton facltes.in order to obtan good results from the mult-crtera methodology, an accurate knowledge of the varous parameters and ther weghts s requred. Although the numercal approach s used n ths study, comparatve approach on some factors needs to be conducted n order to allow professonal personals to make ther fnal decsons. References [1]. Goodland, R.J.A., The urgent transton to envronmental sustanablty. 013, The Envronment General Authorty: Trpol. []. Alamn, S., A. Fewkes, and S. Goodhew. Investgatng the sustanablty of water management n Alwahat, Lbya. n The Sustanable Cty VI Span: Wessex Insttute. [3]. Mahmoud, M.R., H. Fahmy, and J.W. Labade, Multcrtera Stng and Szng of Desalnaton Facltes wth Geographc Informaton System. Journal of Water Resources Plannng and Management (). [4]. Andranne, J. and F. Alardn, desalnaton ste selecton on North-Afrca coasts. Desalnaton, [5]. Study of the water stuaton n Lbya and the strategy for the management of water resources, part 3. 00, General Authorty for Water, Trpol. []. Evaluaton of water stuatton n Lbya. 199, General Water Athurty n Lbya: Trpol. [7]. Alharare, M.S., Decson support system for optmal szng and stng of desalnaton facltes, n The Department of mechancal engneerng 008, Academy of Graduate Studes: Trpol. 90 Page