本文選題：海水淡化　切入點：蒸發(fā)發(fā)電　出處：《天津工業(yè)大學》2017年碩士論文

【摘要】：水資源危機,水質污染,淡水短缺是全球面臨的嚴峻問題。在工業(yè)生產中,淡水用量巨大,火力發(fā)電尤其是用水大戶,其用水量約占工業(yè)總用水量的40%,主要用于鍋爐產生蒸汽和乏汽冷卻用水等。沿海城市電廠有豐富的海水資源,如能利用海水蒸發(fā)產生蒸汽,蒸汽推動汽輪機發(fā)電,用海水對乏汽進行冷凝,將極大地降低用水投資和成本,對節(jié)約水資源,緩解淡水緊缺壓力和實現社會經濟效益最大化以及可持續(xù)發(fā)展具有重大的意義。海水水質成分復雜,含鹽量高,腐蝕性強,不能像淡水一樣直接蒸發(fā)產生蒸汽,蒸汽推動汽輪機發(fā)電。本文探討對海水進行脫硬預處理,將硬度離子——鈣、鎂離子處理至含量為零,再采用蒸發(fā)方式產生蒸汽,由于蒸汽中會夾帶鹽,需要對蒸汽進行洗滌,洗至電導率低于1μs/cm,滿足汽輪機進汽要求,探索出海水直接蒸發(fā)發(fā)電的新工藝。本論文以海水為原料,采用化學沉淀法除鈣,即向海水中加入碳酸鈉將鈣離子以碳酸鈣的形式去除,考察鈣離子的去除率及最佳去除工藝條件,對除鈣后的海水用納濾裝置對鈣、鎂、硫酸根及二價以上離子進行去除處理,對比考察了脫鈣海水和原料海水納濾膜通量和離子截留率的差異,并通過接觸角、SEM、EDX等表征方法研究了膜面污染物的主要成份及其對膜性能的影響,結果表明,鈣離子是造成納濾膜無機污染的主要離子,脫鈣處理能有效減緩海水淡化過程中納濾預處理階段的無機結垢問題,延長納濾膜的使用壽命。對納濾膜產水用碳酸鈉和氫氧化鈉將鈣、鎂離子完全沉淀去除,處理后海水蒸發(fā)產生蒸汽,通過收集蒸汽冷凝水研究蒸汽的品質,分析測定了蒸汽冷凝水的TDS和電導率,確定其是否滿足汽輪機進汽要求及其用于發(fā)電的可行性。實驗結果表明,采用化學脫鈣預處理+納濾+二次化學除鈣鎂的工藝,能有效去除海水中的硬度離子,首次化學脫鈣處理能去除海水中90%以上的鈣離子,剩余鈣離子含量低于40mg/L,采用納濾膜進一步去除鈣、鎂離子及硫酸根,再采用二次化學法除鈣鎂后,鈣、鎂離子基本可完全除去,解決了蒸發(fā)產生蒸汽過程中的結垢問題,所得蒸汽經洗氣塔洗汽后,蒸汽冷凝水的TDS低于1mg/L,電導率低于1μs/cm,蒸汽品質可滿足汽輪機進汽要求,蒸發(fā)海水發(fā)電具有可實現性。
[Abstract]:Water crisis, pollution of water quality and shortage of fresh water are serious problems facing the whole world. In industrial production, the consumption of fresh water is huge, and thermal power generation, especially large water users, Its water consumption accounts for about 40 percent of the total industrial water consumption and is mainly used for boiler steam production and spent steam cooling water etc. Coastal city power plants have abundant sea water resources, such as steam evaporation to produce steam, steam to promote steam turbine power generation, etc. Using seawater to condensate the spent steam will greatly reduce the investment and cost of water, save water resources, relieve the pressure of fresh water shortage, maximize social and economic benefits, and achieve sustainable development. The composition of seawater water quality is complex. Because of its high salt content and strong corrosion, steam can not be evaporated directly as fresh water to produce steam, and steam can drive steam turbine to generate electricity. In this paper, the desalting pretreatment of seawater is discussed, and the hardness ions-calcium and magnesium ions are treated to zero content. The steam is produced by evaporation. Because of the salt in the steam, it is necessary to wash the steam until the conductivity is less than 1 渭 s / cm, which meets the requirement of steam turbine entry, and explores a new process of direct evaporation power generation by seawater. In this paper, the seawater is used as raw material. Calcium removal was carried out by chemical precipitation, in which calcium ion was removed in the form of calcium carbonate by adding sodium carbonate into seawater. The removal rate of calcium ion and the optimum technological conditions were investigated. After removing calcium, calcium and magnesium were treated by nanofiltration device. The difference of nanofiltration membrane flux and ion retention between decalcified seawater and raw seawater was compared. The main components of membrane surface pollutants and their effects on membrane properties were studied by means of contact angle SEMN edX. The results showed that calcium ion was the main ion that caused inorganic pollution of nanofiltration membrane. Decalcification treatment can effectively reduce the inorganic scaling problem in the pretreatment stage of nanofiltration and prolong the service life of nanofiltration membrane. Calcium and magnesium ions are completely precipitated by sodium carbonate and sodium hydroxide for water production of nanofiltration membrane. Steam was produced by evaporation of seawater after treatment. The quality of steam was studied by collecting steam condensate, and the TDS and conductivity of steam condensate were analyzed and measured. The experimental results show that the pretreatment process of chemical decalcification with nanofiltration secondary chemical removal of calcium and magnesium can effectively remove the hardness ions in seawater. The first chemical decalcification treatment could remove more than 90% of calcium ions in seawater. The residual calcium ion content was less than 40 mg / L. The nanofiltration membrane was used to further remove calcium, magnesium ion and sulfate radical. Mg ~ (2 +) can be removed completely, which solves the problem of scaling in the process of vaporization. After the steam is washed by the washing tower, the TDS of steam condensate water is less than 1 mg / L, the conductivity is less than 1 渭 s / cm, and the steam quality can meet the steam intake requirement of steam turbine. Evaporative seawater power generation is realizable.
【學位授予單位】：天津工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM61

【參考文獻】

相關期刊論文 前10條

1 楊寶紅;;新形勢下火電廠節(jié)水減排工作特點及關鍵[J];熱力發(fā)電;2016年09期

2 郭久亦;于冰;;世界水資源短缺:節(jié)約用水和海水淡化[J];世界環(huán)境;2016年02期

3 楊尚寶;;我國海水淡化產業(yè)發(fā)展現狀與建議[J];水處理技術;2015年12期

4 王奕陽;栗鴻強;;反滲透海水淡化投資與運行成本分析[J];水處理技術;2015年10期

5 周棟;傅寅翼;朱麗靜;郭志毅;劉富;薛立新;;納濾預處理反滲透海水淡化研究進展[J];膜科學與技術;2015年03期

6 石效卷;李璐;張濤;;水十條 水實條——對《水污染防治行動計劃》的解讀[J];環(huán)境保護科學;2015年03期

7 劉紅波;;水資源現狀及解決水資源短缺的有效途徑[J];農業(yè)與技術;2015年10期

8 楊坤;陳惠雄;;水危機新論[J];經營與管理;2015年03期

9 安增琴;;火電廠節(jié)水研究與實踐[J];廣東化工;2015年02期

10 王韜;王樞;王毅;陳洪巖;柳琦杰;;卷式納濾膜分離糖鹽混合溶液[J];水處理技術;2015年01期

，

本文編號：1657211