| Seawater Desalination technology is an important way to solve the shortage offresh water has been accepted by the word, but it’s further development has beenrestricted by the high energy consumption. Integration and optimization ofdesalination technology is considered to be the most promising technology.Co-generation desalination technology can use the waste heat steam and electricity ofthe power plant to provide energy for the desalination system, so it not only take fulladvantage of the energy but also further reduce the cost of fresh water produced bydesalination method. In that case, co-generation desalination technology will becompeting researched by the world. In order to meet the water and electricity demand,the production loads of power and desalination system will wave greatly, especiallythe power plant if the power and desalination system run independently, as the waterand electricity demand load are changing with the time. This problem can beefficiently solved by the production scheduling of Co-generation desalination system.When the electricity demand is higher, the electricity produced by the power plant isused to meet the electricity demand; when lower, the extra power can be used by thedesalination system to produce fresh water which can be storeged to meet the waterdemand. Therefore, it is a very significant issue to study the production scheduling ofcogeneration system.Two hybrid multi-stage flash (MSF) and reverse osmosis (RO) desalinationsystem are analysised in this paper. The system and economic model of the twosystem are established, and the simulation program is presented as a non-linerprogramming, which is solved by GAMS program with the maximizing totaleconomic benefits as the objective. The relationship of the fresh water cost and theproduction water cogeneration with the water production ratio between MSF and RO.The results show that: the fresh water cost reduces with the water production ratio yincreases, while the production water cogeneration rises in the hybrid MSF/ROsystem with the cooling water rejected form MSF fed into RO; the fresh water cost and cogeneration are both reduce with the production ratio y increases in the hybridMSF/RO system with the brine water rejected form RO fed into MSF.The simulation and optimization of the cogeneration desalination system isstudied in this paper. The optimization model of the cogeneration system is build, andthe program is presented as a non-liner programming, which is solved by GAMSprogram with the minimizing fresh water cost as the objective. The optimizationdesign of the co-generation desalination, with the total water production of8000t/hand no required for electricity, is explored, and is compared with the cases in whichthe water production are3000t/h,5000t/h and12000t/h. The results show that: theoptimal operation of co-generation system in the case that the total water productionis8000t/h and the electricity production is not required is the integration of powerplant, MSF and RO, in which all the steam from the power plant is used as the heatingsteam for the MSF and the feed water of RO is part of the rejecting cooling water ofthe MSF, and the optimal water production ratio between MSF and RO is0.45; thefresh water cost and the water production ratio show a decreasing trend with thewith the increasing of the total water production; the co-generation desalinationsystem can not only meet the water demand but also can supply a certain amount ofelectricity to the outside by optimal design, and it not only takes full use of the energybut also further reduces the water cost.The study of the production scheduling of the co-generation system in the typicalday is presented in this paper based on the analysis of the typical daily water andelectricity demand and the timed power tariff. The mathematical model of theproduction scheduling of the co-generation system is established, and the schedulingproblem is described as a nonlinear programming problem, which is solved by GAMSprogram with the maximizing total economic benefits as the objective. The resultsshow that:(1) the MSF and RO show the same variation in the four seasons, that isthe water production of MSF just has a little change over the time while the RO has agreater change;(2) when the power demand is lower, the water production of RO andthe total water production increase, in that case, the remaining amount of water isstored in the tank, when higher, the RO and total water production both decrease, the water produced can not meet the water demand, in that case, the water stored in thetank is used to meet the shortfall;(3) the total revenue and the energy efficiency canbe increased by scheduling the co-generation system based on the typical daily waterand electricity demand and the timed power tariff, as when the electricity is lower, thesystem produces more water, when higher, more power;(4) the fluctuations in theproduction load of the power plant is significantly reduced by the productionscheduling of the co-generation system, so that the power plant can operation stablyand efficiently.The study of the production scheduling of the co-generation system in theseasons is presented in this paper based on the analysis of the seasons water andelectricity demand, in which the fluctuations of the coal price is considered.Themathematical model of the production scheduling of the co-generation system isestablished, and the scheduling problem is described as a nonlinear programmingproblem, which is solved by GAMS program with the maximizing total economicbenefits as the objective. The results show that:(1) the water production of MSF justhas a little change over the season, while the RO changes greatly.(2) the waterproduction is higher than the water demand in spring, autumn and winter, so the tankstore water in these seasons; but in summer, the power produced by the power plant isall used by the outside, so the water production of RO is zero in this season and thewater production is lower than the demand, in that case, the water stored in the tank isused to meet the shortage.(3) The water production can meet the water demand in allyear by scheduling the production of the co-generation system.(4) The total revenueof the co-generation system with considering the changes of the coal price is lowerthan unconsidering, it shows that the change of the coal price has impact on theeconomic benefits of the system, so it is very meaningful and necessary to considerthe fluctuations of the coal price when scheduling the co-generation system with thetotal economic benefits as the objective. |
