燃气电厂循环冷却水排污水处理技术研究

发布时间：2018-04-24 06:23

本文选题：循环冷却水排污水 + 超高石灰铝法　；参考：《华北电力大学》2017年硕士论文

【摘要】：循环冷却水系统是电厂中的用水大户,排污水量及补给水量均较高,水质中由于Cl~-、Ca~(2+)及SO_4~(2-)等离子的存在会造成设备的腐蚀和结垢等问题,燃气电厂由于不具备脱硫系统,导致循环冷却水排污水无法回用于其它处理系统,只能外排而造成浪费。超高石灰铝法是一种由石灰软化法及混凝沉淀法发展而来的新型除氯方法,通过添加Ca(OH)_2及Na Al O_2与水中阴离子反应,形成类水滑石型物质(LDH),同时也能去除溶液中的Ca~(2+)及SO_4~(2-)。本课题旨在研究使用超高石灰铝法处理模拟水质,检测其各项离子浓度及指标,得到最佳去除效果及去除条件;通过分析其产物组成及反应动力学预测反应机理;并初步处理燃气电厂循环冷却水实际排污水,使其出水水质满足循环冷却水补给水要求并可回用于冷却水系统。当模拟水质中只含有500mg/LCl~-及280mg/LCa~(2+)时,通过正交实验及单因素实验分析得出,最佳药剂投加比例为n(Ca):n(Al):n(Cl)=5:3:1,最佳反应条件为温度25℃,震荡时间2h,此时Cl~-出水浓度为155mg/L,去除率为71.24%;Ca~(2+)出水浓度为62mg/L,去除率为78.74%。药剂投加比例对去除率影响最大,Cl~-初始浓度的降低会极大抑制Cl~-去除率。同时建立了各工艺条件对Cl~-、Ca~(2+)去除率影响的数学模型。当水质中添加500mg/LSO_4~(2-)后,会极大影响Cl~-去除率,且随SO_4~(2-)浓度增加去除率快速减少,但会一定程度上促进Ca~(2+)的去除。采用二次处理或微过量投加药剂的工艺可以解决该问题。当n(Ca):n(Al):n(SO_4~(2-)+Cl~-)=6.3:4.2:1,Cl~-去除率为72.76%,Ca~(2+)和SO_4~(2-)去除率均可以超过90%。通过对产物进行XRD分析及探究Cl~-去除反应动力学,发现该方法去除机理为水质中的Cl~-及SO_4~(2-)会与药剂水解产生的Ca~(2+)及Al~(3+)进行反应,生成Ca_4Al_2Cl_2(OH)_(12)及Ca_6Al_2(SO_4)_3(OH)_(12),且水质中游离的Ca~(2+)会促使反应正向进行,该反应预计为三级反应,Cl~-反应速率常数为4.607×10~(-4)(mmol·L)~(-2)·min~(-1)。使用该方法处理实际电厂循环水排污水发现,三种离子去除率均在72%以上,出水浓度可以满足补给水水质要求,但由于出水p H较高需要进行酸化处理。酸化处理后的水质相较于原水水质更趋于稳定状态。由于该方法处理成本较低,设备流程简单,因此具有工业应用前景。但出水电导率和TDS较高是该方法的最大弊端,同时过滤工艺及固废处理工艺也应是未来研究的重点。
[Abstract]:The circulating cooling water system is the big water user in the power plant. The water discharge and the recharge water are all high. The water quality in the water can cause the corrosion and scaling of the equipment because of the existence of Cl~-, Ca~ (2+) and SO_4~ (2-) plasma. Because the gas power plant does not have the desulfurization system, it can not be used back to other treatment systems. The ultra high lime aluminum method is a new method of dechlorination developed by lime softening and coagulating precipitation. By adding Ca (OH) _2 and Na Al O_2 to the water anions, it forms a hydrotalcite like substance (LDH) and can also remove Ca~ (2+) and SO_4~ (2-) in the solution. The purpose of this study is to study the use of ultra-high lime aluminum. The method is used to treat the simulated water quality, to detect the ion concentration and index, to get the best removal efficiency and removal conditions, to predict the reaction mechanism by analyzing the composition and reaction kinetics, and to deal with the actual discharge of the circulating cooling water in the gas power plant, so that the water quality can meet the requirements of the circulating cooling water and can be used for the cooling water. When the simulated water contains only 500mg/LCl~- and 280mg/LCa~ (2+), the optimum dosage is n (Ca): n (Al): n (Cl) =5:3:1, and the optimum reaction condition is 25 C, and the oscillation time is 2H. At this time, the effluent concentration is 71.24%. The addition ratio of 78.74%. has the greatest impact on the removal rate, and the reduction of the initial Cl~- concentration will greatly inhibit the removal rate of Cl~-. At the same time, the mathematical model of the effect of the process conditions on the removal rate of Cl~- and Ca~ (2+) is established. When 500mg/LSO_4~ (2-) is added to the water, the Cl~- removal rate is greatly affected and the removal rate increases with the SO_4~ (2-) concentration. The reduction of Ca~ (2+) can be reduced to a certain extent. The problem can be solved by the process of two treatment or slightly overdosing agent. When n (Ca): n (Al): n (SO_4~ (2-) +Cl~-) =6.3:4.2:1, Cl~- removal rate is 72.76%. It is found that the removal mechanism of this method is that the Cl~- and SO_4~ (2-) in water will react with Ca~ (2+) and Al~ (3+) produced by the hydrolysis of the agent to produce Ca_4Al_2Cl_2 (OH) (12) and Ca_6Al_2 (SO_4) _3 (12), and the free water in the water will lead to the positive reaction, which is expected to be a grade three reaction, and the rate constant of the reaction is 4.607 x (- 4) (mmol. L) ~ (-2). Min~ (-1). Using this method, the removal rate of three kinds of ion removal is more than 72%. The effluent concentration can meet the water quality requirements of the recharge water, but the effluent P H needs to be acidified. The water quality after acidification is more stable than the original water quality. The treatment cost is low, the equipment process is simple, so it has the prospect of industrial application. But the high conductivity of the effluent and high TDS is the biggest disadvantage of this method. At the same time, the filtration process and the solid waste treatment process should be the focus of the future research.

【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X773

【参考文献】