Mitigating NH3 Vaporization from an Aqueous Ammonia Process for CO2 Capture
Mitigating NH3 Vaporization from an Aqueous Ammonia Process for CO2 Capture
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DOI：
10.1515/1542-6580.2711
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发表时间：
2011-07
影响因子：
1.6
通讯作者：
W. Budzianowski
中科院分区：
文献类型：
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作者：
W. Budzianowski
与其他现有的基于反应吸收的 CO2 捕集工艺相比，氨水工艺 (AAP) 具有多种有利的技术特点，例如提高 CO2 吸收负载能力、无氧化溶剂降解、无腐蚀问题、高 CO2 吸收通量和溶剂再生所需的低能量输入。它还具有捕获多种烟气成分（SO2、NOX 和 CO2）并生产增值化学品的潜力，例如通常用作肥料的硫酸铵、硝酸铵和碳酸氢铵。不幸的是，AAP 的一个主要缺点是 NH3 挥发，导致 NH3 蒸发到烟道气中。因此，本文介绍了实验和数值研究的结果，旨在深入了解 AAP 并开发新方法来减轻不需要的 NH3 蒸发。为此，研究了三种类型的反应器配置：（i）填充床，（ii）降膜和（iii）膜。在逆流填充床反应器中实现的小规模实验表明，在低温、pH和烟气流量条件下以及在高压和氨水流量条件下，可以最大限度地减少NH3蒸发。此外，从降膜反应器中实现的 AAP 的详细二维建模发现，可以通过利用传质负增强和迁移传质的机制来减轻 NH3 蒸发。最后，讨论了使用膜促进 AAP 反应器的潜在好处。
An aqueous ammonia process (AAP) offers several advantageous technological features over other existing reactive absorption-based CO2 capture processes such as increased CO2 absorption loading capacity, no oxidative solvent degradation, no corrosion problems, high CO2 absorption fluxes and low energy input needed for solvent regeneration. It has also the potential of capturing multiple flue gas components (SO2, NOX, and CO2) and producing value added chemicals, such as ammonium sulfate, ammonium nitrate and ammonium bicarbonate, which are commonly used as fertilizers. Unfortunately, a major drawback of the AAP is NH3 volatility resulting in NH3vaporization to the flue gas. Therefore, the current article presents the results of experimental and numerical investigations directed at in-depth understanding of the AAP and at developing of new methods for mitigating the unwanted NH3 vaporization. For this purpose three types of reactor configurations are studied: (i) packed bed, (ii) falling film and (iii) membrane. The bench-scale experiments realized in the counter-current packed bed reactor reveal, that NH3 vaporization can be minimized under the conditions of low temperature, pH, and flow rate of flue gas and under the conditions of high pressure and flow rate of aqueous ammonia. Further, from the detailed 2D modeling of the AAP realized in the falling film reactor it is found, that NH3 vaporization can be mitigated by making use of the mechanisms of negative enhancement of mass transfer and of migrative mass transport. Finally, the potential benefits of using membrane facilitated AAP reactors are discussed.