Abstract:

In response of problems such as ammonia escape, high regenerated energy and low absorbed rate in the late stage, which exist in the research of carbon capture by ammonia now, this paper presents a novel process of carbon capture by ammonia with reinforced crystallization, using a new type of aqueous ammonia-ethanol mixing absorbent. The effect of absorption and crystalline regularity under different absorbent ingredients, different absorption temperatures, different flue gas flow, and different CO₂ volume fraction is studied using a semi-continuous bubbling reaction system. The experimental results show that mixing absorbent with relatively high ratio of ethanol, relatively low absorption temperature, and higher gas flow and larger volume fraction of CO₂ will be favorable for strengthening of process, including that the appearing time of crystals in the absorbent could bring forward and the ratio of ammonia account in the crystals to the initial total ammonia could be up to 38.75% as well as the CO₂ absorption capacity was improved significantly compared to pure aqueous ammonia. Novel ideas presented in this paper could be that a carbon capture process by ammonia with reinforced crystallization is suggested, and better conditions were given for improving absorption and reducing consumption of desorption energy. All basic data and results provided by this paper could be useful for further study of this new process.

Key words: mixing absorbent, absorption capacity, regeneration, crystallization, bubbling reactor

摘要：

针对目前氨法二氧化碳捕集技术中存在的氨逃逸、再生能耗高、反应后期吸收率低等问题提出了强化结晶氨法捕碳工艺,采用氨水乙醇组成的混合吸收液,利用半连续鼓泡反应系统研究了实验过程中吸收液组成、吸收温度、烟气流量及烟气中CO₂体积分数对吸收及结晶规律的影响。实验结果表明,混合吸收液中选用高比例乙醇、较低的吸收温度、较高的烟气流量以及较大的CO₂体积分数有利于吸收液中晶体出现时间提前,有利于强化结晶过程,晶体含氨量占初始氨总量的分数可达38.75%,并且混合吸收液的CO₂吸收能力较纯氨水工况明显提高。创新之处在于:提出了一种强化结晶氨法捕碳工艺,对氨水乙醇混合吸收液的吸收及结晶规律进行研究,给出了能够改善吸收效果并利于结晶过程的有利工况。为接下来新工艺的进一步研究提供基础数据和参考。

关键词: 混合吸收液, 吸收能力, 再生, 结晶, 鼓泡反应器