Research On The Theory Of Seawater Evaporation Steam Generators

Water resource shortage and pollution have been serious problems in the world.In industrial production,the amount of fresh water is huge and the water consumption in power plant accounts for about 40%of the total industrial water consumption.It is mainly used for boiler steam and steam cooling.Coastal city power plants are rich in seawater resources,the uses of seawater to produce steam,to promote steam turbine power generation,to condense steam,will greatly reduce water investment and cost.Water resource saving could ease fresh water stress and achieve the maximization of social and economic benefits and promote the sustainable development with great significance.Seawater water composition is complex,with high salt content,and high capability corrosive.Therefore,it can not evaporate as fresh water to produce steam.In this paper,the pretreatment of desalination is investigated almost completely.The effluent ions-calcium,magnesium ions were got rid of and then use evaporation to produce steam.Because the steam was entrained with salt,the need for steam to wash,wash to low conductivity less than 1?s/cm,in order to meet the requirements of steam turbine steam,which can explore the new technology of direct evaporation of water generation.In this paper,seawater as raw material,the use of chemical precipitation in addition to calcium.Adding calcium carbonate to the sea water to remove the calcium ions in the form of calcium carbonate,to examine the removal rate of calcium ions and the best removal process conditions,the calcium removal of seawater with nanofiltration device on calcium,magnesium,sulfate and divalent.The effects of decalcified seawater and raw material seawater nanofiltration membrane flux and ion interception were investigated.The main components of membrane foulants were studied by contact angle,SEM and EDX.The results show that calcium ions are the main ions that cause inorganic fouling of nanofiltration membrane.Decalcification treatment can effectively avoid the problem of inorganic fouling during nanofiltration pretreatment during seawater desalination,and prolong the life of nanofiltration membrane life.Calcium and magnesium ions were completely precipitated with sodium carbonate and sodium hydroxide.The steam was evaporated with seawater,and the quality of steam was studied by collecting steam condensate.The TDS and conductivity of steam condensed water were analyzed to determine whether it met the steam turbine inlet requirements and its feasibility for power generation.The results show that the process of chemical desalination pretreatment +nanofiltration + secondary chemical removal of calcium and magnesium process,can effectively remove the hardness of seawater ions.The first chemical decalcification treatment can remove more than 90%of seawater calcium ions,with the remaining calcium ion content of less than 40mg/L.The use of nanofiltration membrane can further remove calcium,magnesium ions and sulfate,and then with the second chemical method,calcium,magnesium ions can be completely removed,to solve the evaporation process fouling problem.After the scrubbing tower washing steam,the steam condensate TDS was less than lmg/L.The conductivity less than 1?s/cm,steam quality met the steam turbine steam inlet requirements,evaporation of seawater power is achievable.Therefore,the fouling problem in the evaporation process can be solved.