Role of absorber and desorber units and operational conditions for N-nitrosamine formation during amine-based carbon capture
Role of absorber and desorber units and operational conditions for N-nitrosamine formation during amine-based carbon capture
复制标题
吸收塔和解吸塔装置的作用以及胺基碳捕获过程中 N-亚硝胺形成的操作条件
DOI：
10.1016/j.watres.2019.115299
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发表时间：
2020
期刊：
影响因子：
12.8
通讯作者：
Mitch William A.
中科院分区：
文献类型：
--
作者：
Wang Zimeng;Zhang Zhong;Mitch William A.
有机胺与烟气NOx反应生成的致癌性N-亚硝胺是基于胺的燃烧后CO2捕集技术应用中的一个重要问题。利用一个先进的试验装置与相互连接的吸收器和解吸器单元，我们评估的重要性forN-亚硝胺形成的解吸器相对于吸收器，和任何协同作用之间的两个单元。脱附温度和烟气成分的变化表明，N-亚硝胺的形成主要发生在吸收器中，由新鲜的单乙醇胺（MEA）。N-亚硝胺的形成是由高浓度的NO2和O2烟气驱动，虽然NO也有贡献。与此相反，N-亚硝胺的形成从哌嗪（PZ）驱动的反应与亚硝酸盐在加热解吸，并加速与亚硝酸盐的积累。模拟老化MEA溶剂（高亚硝酸盐，1.5%肌氨酸作为仲胺降解产物的代表）的补充实验表明，对于N-亚硝胺的形成，解吸剂变得比吸收剂更重要一个数量级。对于新鲜MEA溶剂，将解吸器温度从110 °C增加到130 °C促进N-亚硝胺的热分解，将N-亚硝胺积累速率降低两倍。与试验装置相比，使用单独的吸收柱和类似高压釜的处理来模拟解吸单元的流行做法预测了方向，但低估了N-亚硝胺形成的幅度。由于N-亚硝胺积累率是竞争形成和热分解过程的净结果，因此可能需要使用连续循环试验装置来了解不同操作条件的影响。
The formation of carcinogenicN-nitrosamines from reactions between solvent amines and flue gas NOxis an important concern for the application of amine-based processes to capture CO2post-combustion. Using an advanced test rig with interconnected absorber and desorber units, we evaluated the importance forN-nitrosamine formation of the desorber relative to the absorber, and any synergism between the two units. Variations in desorber temperature and in flue gas composition indicated thatN-nitrosamine formation from fresh monoethanolamine (MEA) occurred predominantly in the absorber.N-nitrosamine formation was driven by high NO2and O2flue gas concentrations, although NO also contributed. In contrast,N-nitrosamine formation from piperazine (PZ) was driven by reactions with nitrite in the heated desorber, and accelerated concurrent with nitrite accumulation. A complementary experiment simulating aged MEA solvent (high nitrite, 1.5% sarcosine as a proxy of secondary amine degradation products) suggested the desorber becomes an order of magnitude more important than the absorber forN-nitrosamine formation. For fresh MEA solvent, increasing the desorber temperature from 110 °C to 130 °C promoted thermal decomposition ofN-nitrosamines, reducingN-nitrosamine accumulation rates two-fold. Compared to the test rig, the prevailing practice of using separate absorber columns and autoclave-like treatments to mimic desorber units predicted the direction, but underestimated the magnitude ofN-nitrosamine formation. BecauseN-nitrosamine accumulation rates are the net result of competing formation and thermal decomposition processes, use of continuously cycling test rigs may be necessary to understand the impacts of different operating conditions.