火电厂反渗透浓水电解除氨氮及制氯性能研究

发布时间：2018-06-23 10:37

本文选题：火电厂 + 线性伏安法　；参考：《长安大学》2015年硕士论文

【摘要】：火电厂酸碱再生废水含较高浓度的氨氮,总溶解固体以钠离子、氯离子为主,二价结垢离子含量很低,因此采用反渗透技术对上述废水进行回收处理,反渗透后的淡水可以进行回用,但其浓水含氨氮和氯化钠较高,不能达到回用标准。因此需要对反渗透浓水进行再处理。本文提出使用电解方法对酸碱废水经反渗透后的浓水进行处理,通过电化学性能测试选择合适的阳极材料,同时通过电解水样研究了电流密度、pH、TDS、阳极材料对除氨、制氯、能耗、槽压以及对极板结垢的影响,并提出预防极板失效的措施。获得的主要结论如下:通过电化学阳极测试实验,测定了四种钛基金属氧化物涂层DSA阳极的析氧电位与析氯电位。四种DSA阳极材料分别为涂层配方不同的Ti/RuO2-Ir O2(R1和R2)与涂层配方不同的Ti/IrO2-Ta2O5(T1和T2)。实验结果表明:所选的四种DSA阳极材料的析氯电位在1100mVvs.SCE~1125mVvs.SCE之间,这满足GBT22839-2010《电解海水次氯酸钠发生装置技术条件》中对阳极析氯电位的技术要求;析氧电位在1240mVvs.SCE~1275mVvs.SCE之间。上述四种材料均可作为析氯电极使用。综合考虑技术、经济等因素,选择析氯电位低、析氧电位高且价格较便宜的Ti/RuO2-Ir O2材料作为电解实验所用的DSA电极。电流密度对氨的降解及氧化速率影响较大,电流密度高时,氨的降解时间短,氨的瞬时氧化速率高;电解过程中氨降解的平均能耗相对较高,但是幅度不大。水样的TDS、pH对电解过程中氨的氧化速率、总氯浓度变化及氯离子转化率影响相对较小;TDS越低、电流密度越高、pH越高,电解过程中氨的降解平均能耗相对越高,但增大幅度不大;pH=7.05时,氨的平均氧化速率较pH=9.18略有提高。但由于用反渗透工艺回收精处理酸碱废水时所产的浓水呈碱性,pH在9.0以上,若调pH至中性需消耗一定量的盐酸,因此运行费用会有所增加。两种阳极材料Ti/RuO2-Ir O2(R1)与Ti/RuO2-IrO2(R2)在相同工况条件下电解除氨及制氯时,结果表明:Ti/RuO2-IrO2(R2)的除氨及制氯效果更好;在不同工况条件下,随着电解时间延长,水样中氨浓度呈线性下降,氯离子浓度也逐渐降低,氨去除完后总氯浓度迅速上升,氨的平均能耗逐渐增大,水样中总氯浓度在电解初期缓慢上升并达到2000mg/L后基本保持不变,直到氨被完全去除完后,总氯浓度迅速上升,继续进行短时间电解总氯浓度即可达到6000mg/L左右。在相同工况条件下,高温更易使极板结垢;极板结垢对电解除氨以及制氯的效果有明显影响。极板清洁程度越高,氨的氧化速率及氯离子转化率越高,氨的平均能耗越小;在整个电解过程中,槽电压随着时间的延长而增大;电流密度越大,槽电压越大;在氨完全去除完后,总氯在在短时间内增长很快。
[Abstract]:The acid and alkali regenerative wastewater of thermal power plant contains high concentration of ammonia nitrogen, the total dissolved solids are mainly sodium ion and chlorine ion, and the divalent scaling ion content is very low, so reverse osmosis technology is used to recycle the wastewater. The fresh water after reverse osmosis can be reused, but the concentrated water contains high ammonia nitrogen and sodium chloride, which can not reach the reuse standard. Therefore, it is necessary to retreat the concentrated reverse osmosis water. In this paper, electrolytic method is proposed to treat concentrated water after reverse osmosis (RO) in acid-base wastewater. Appropriate anode materials are selected by electrochemical performance test. At the same time, the current density of pH TDSs is studied through electrolytic water sample. The anodic material is used to remove ammonia, produce chlorine, and consume energy. The influence of tank pressure and scale on the plate is discussed, and the measures to prevent the plate from failure are put forward. The main conclusions are as follows: the oxygen evolution potential and chlorine evolution potential of four kinds of titanium based metal oxide coated DSA anodes were measured by electrochemical anode test. The four kinds of DSA anode materials are Ti / Ruo _ 2-Ir _ 2O _ 2 (R _ 1 and R _ 2) with different coating formula and Ti / IrO _ 2-Ta _ 2O _ 5 (T _ 1 and T _ 2) with different coating formula respectively. The experimental results show that the chlorine evolution potential of the four DSA anode materials is between 1100mVvs.SCEN 1125mVvs.SCE, which meets the technical requirements of the GBT22839-2010 anodic chlorine evolution potential in GBT22839-2010, and the oxygen evolution potential between 1240mVvs.SCE1275mVvs.SCE. The above four materials can be used as chlorine evolution electrodes. Considering the technical and economic factors, the Ti / Ruo _ 2-Ir _ 2O _ 2 material with low chlorine evolution potential, high oxygen evolution potential and low cost was selected as the DSA electrode for electrolysis experiment. The current density has a great influence on the degradation and oxidation rate of ammonia. When the current density is high, the degradation time of ammonia is short and the instantaneous oxidation rate of ammonia is high, and the average energy consumption of ammonia degradation in electrolysis is relatively high, but the amplitude is not large. The TDS pH of water sample has a relatively small effect on ammonia oxidation rate, total chlorine concentration change and chloride conversion rate. The lower the TDs is, the higher the current density is, and the higher the pH is, the higher the average energy consumption of ammonia degradation in electrolysis process is. However, when pH = 7.05, the average oxidation rate of ammonia was slightly higher than that of pH9.18. However, the concentrated water produced by the recovery of acid and alkali wastewater by reverse osmosis process is above 9.0. If the pH is adjusted to neutral, a certain amount of hydrochloric acid will be consumed, so the running cost will be increased. The results show that the ammonia concentration in water samples decreases linearly with the increase of electrolytic ammonia concentration under the same operating conditions. The results show that the ammonia removal and chlorine preparation of the two kinds of anode materials Ti / RuO _ 2-IrO _ 2 (R _ 2) are better than those of Ti / R _ 2O _ 2-IrO _ 2 (R _ 2) under the same operating conditions, and the ammonia concentration in the water samples decreases linearly with the prolongation of the electrolytic time under different operating conditions. After ammonia removal, the total chlorine concentration increased rapidly, the average energy consumption of ammonia gradually increased, and the total chlorine concentration in the water sample increased slowly at the beginning of electrolysis and reached 2000mg / L, until the ammonia was completely removed. The concentration of total chlorine increased rapidly, and the concentration of total chlorine reached about 6 000 mg / L in a short period of time. Under the same working conditions, it is easier to scale the plate at high temperature, and the scale of the plate has a significant influence on the effect of electrolytic ammonia removal and chlorine production. The higher the cleanness of the electrode plate, the higher the oxidation rate of ammonia and the conversion of chloride ion, the smaller the average energy consumption of ammonia, the more the cell voltage increases with the prolongation of time in the whole electrolysis process, and the greater the current density is, the greater the cell voltage is. After the ammonia is completely removed, the total chlorine increases rapidly in a short period of time.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X773

【参考文献】