Chemical Industry and Engineering Progress ›› 2024, Vol. 43 ›› Issue (4): 2191-2200.DOI: 10.16085/j.issn.1000-6613.2023-0521

• Resources and environmental engineering • Previous Articles    

Impacts of CeO2 oxygen carriers on the conversion of mercury in chemical looping combustion of coal

WANG Xudong1,2(), LIU Dunyu1,2(), XU Kailong1,2, LIU Qiuqi1,2, FAN Yunpei1,2, JIN Jing1,2   

  1. 1.School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
    2.Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, Shanghai 200093, China
  • Received:2023-04-04 Revised:2023-05-09 Online:2024-05-13 Published:2024-04-15
  • Contact: LIU Dunyu

CeO2载氧体对煤化学链燃烧中汞迁移影响机制

王旭栋1,2(), 刘敦禹1,2(), 许开龙1,2, 刘秋祺1,2, 范昀培1,2, 金晶1,2   

  1. 1.上海理工大学能源与动力工程学院,上海 200093
    2.上海市动力工程多相流动与传热重点实验室,上海 200093
  • 通讯作者: 刘敦禹
  • 作者简介:王旭栋(1999—),男,硕士研究生,研究方向为化学链燃烧。E-mail:m18832002021@163.com
  • 基金资助:
    国家自然科学基金(51706143);上海市自然科学基金面上项目(21ZR1444400)

Abstract:

Mercury pollution has attracted increasing attention due to serious harm to the human beings and ecosystem. This study aims to analyze the effects of CeO2 oxygen carriers on the conversion of mercury during coal chemical looping combustion. The combustion characteristics of "CeO2+coal", "SiO2+coal" and "coal" in the fluidized bed reactor were investigated experimentally. In gasification atmosphere, the reaction between oxygen carrier and coal was mainly converted to CO2 and a small amount of compositions including CO, CH4, and H2 . "CeO2+coal" system consumed the largest amount of O2 and produced the largest amount of CO2, indicating that the CeO2 oxygen carriers contributed to the fully combustion of the coal. Mercury was mainly released as Hg0 in the gasification atmosphere, and the Hg0 release from "CeO2 + coal" accounted for 49.75% of the total mercury, which was significantly lower than that of the system without oxygen carriers. In air atmosphere, mercury was released in the form of Hg2+ with a small amount. The Hg0 and Hg2+ release from "CeO2 + coal" system were both lower than those of the "coal" system. By changing the different locations between CeO2 oxygen carriers and coal in experiments, it was shown that under gasification atmosphere, CeO2 oxygen carriers had weak adsorption capacity for Hg0, and their catalytic and oxygen release properties were the key factors in removing Hg0, and the catalytic activity played a major role. Under gasification atmosphere, CO2 could replenish the lattice oxygen consumed in CeO2, thus improving its catalytic and regenerative performances. XPS analysis of the CeO2 oxygen carriers after reduction and oxidation showed the peak position for Ce3+ in Ce 3d disappeared and all of them were converted to Ce4+, which indicated that the CeO2 oxygen carrier had good cyclic performance.

Key words: chemical looping combustion, cerium dioxide, oxygen carrier, coal, mercury

摘要:

汞污染因其对人类和生态系统的严重危害而日益受到人们的关注,本研究旨在分析CeO2载氧体在煤化学链燃烧过程中对汞迁移的影响。通过实验比较了“CeO2+煤”“SiO2+煤”“煤”在流化床反应器中的燃烧状况,在气化氛围中,载氧体与煤反应主要转化为CO2和少量CO、CH4、H2等成分,“CeO2+煤”体系消耗了最多的O2,产生了最多的CO2,表明CeO2载氧体促使煤燃烧更加充分。汞在气化氛围下主要以Hg0的形式释放,“CeO2+煤”的Hg0释放量占总汞量的49.75%,明显低于无载氧体组。汞在空气氛围下主要以Hg2+的形式再次微量释放,“CeO2+煤”的Hg0和Hg2+释放量均低于纯煤组。通过改变CeO2载氧体和煤之间的不同位置,表明在气化氛围下CeO2载氧体对Hg0的吸附作用很弱,其催化性和释氧作用是脱除Hg0的关键因素,且催化性占据主要地位。在气化氛围下,CO2可以补充CeO2中消耗掉的晶格氧使其具有更好的催化和再生性能。通过对还原/氧化后CeO2载氧体进行XPS(X射线光电子能谱分析仪)分析,发现Ce 3d中的Ce3+峰值消失全部转化为Ce4+,表明CeO2载氧体具有良好的再生性能。

关键词: 化学链燃烧, 二氧化铈, 载氧体, 煤,

CLC Number: 

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