Sulfite oxidation under heterogeneous conditions and responses for pH and oxidation reduction potential (ORP)

doi:10.16085/j.issn.1000-6613.2017.01.050

Abstract

Abstract: Forced oxidation is a main slurry oxidation method in wet flue gas desulfurization(WFGD),and there exists a series problems,such as deposition and slagging in WFGD system、inadequate oxidation and per-oxidation. Based on the nature of redox reaction in slurry oxidation process,this paper puts forward pH and oxidation reduction potential(ORP)dual control strategy to solve the above problems. The response for pH and ORP in calcium sulfite oxidation process was experimentally study of under heterogeneous conditions. the mechanism of response to the occurrence was analyzed in-depth. The results indicated that both pH and ORP showed a non-linear change characteristic in the oxidation process. pH determined by concentration of SO₃^2- ions,tends to gradually reduce from alkaline to neutral pH monitoring data reflects the actual concentration of the SO₃^2- ions. There is a revulsion in the ratio of ORP changes,and the time of the revulsion is accordance well with the platform of the oxidation rate. Calcium sulfite oxidation occurred mainly in the first two stages of potential changes,and the dissolved oxygen accumulates and saturates in the next two stages. ORP turns out subsequently steady after a short-term rise,which demonstrates calcium sulfite oxidation reaching a stable stage. The results provide an effective theoretical basis for pH and ORP oxidation dual control in WFGD.

Key words: desulfurization slurry, calcium sulfite oxidation, pH and ORP oxidation dual control

摘要： 目前脱硫浆液氧化控制方式主要为强制氧化且存在着脱硫系统结垢、氧化不充分和过氧化等一系列问题。基于脱硫浆液的氧化过程为氧化还原反应的本质，为解决上述问题，本文提出了pH和氧化还原电位（ORP）双控制策略。实验研究了多相条件下亚硫酸钙氧化过程中pH与ORP的响应，并深入分析响应发生的机理。结果表明：氧化过程中pH、ORP均表现出了非线性的变化特性，pH从碱性逐渐降低并趋于中性，由SO₃^2-离子的含量决定。pH在线监测数据可以反映SO₃^2-离子的实际含量；ORP变化过程中的斜率存在一个“突跃”，“突跃”发生的时间与氧化率平台出现的时间大体对应。CaSO₃的氧化主要发生在电位变化的前两个阶段，后两个阶段主要发生溶氧的积累和饱和。ORP短期上升随后稳定表明亚硫酸钙氧化达到稳定阶段。研究为脱硫浆液pH与ORP氧化双控制的实施提供了理论基础。

关键词: 脱硫浆液, 亚硫酸钙氧化, pH与ORP双控制

CLC Number:

X701

MA Shuangchen, YANG Jing, ZHANG Linan, HUA Jizhou, WEN Jiaqi, GAO Ran. Sulfite oxidation under heterogeneous conditions and responses for pH and oxidation reduction potential (ORP)[J]. Chemical Industry and Engineering Progree, 2017, 36(01): 383-390.

马双忱, 杨静, 张立男, 华继洲, 温佳琪, 高然. 多相条件下亚硫酸钙氧化及pH、氧化还原电位(ORP)响应[J]. 化工进展, 2017, 36(01): 383-390.

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