MOE Key Laboratory of Thermo-Fluid Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, Shaanxi, China.
MOE Key Laboratory of Thermo-Fluid Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, Shaanxi, China.
J Environ Manage. 2018 Jul 15;218:50-58. doi: 10.1016/j.jenvman.2018.04.057. Epub 2018 Apr 14.
Biomass combustion under the oxy-fuel conditions (Oxy-biomass combustion) is one of the approaches achieving negative CO emissions. KCl, KCO and KSO, as the major potassium species in biomass ash, can catalytically affect biomass combustion. In this paper, the catalysis of the representative potassium salts on oxy-biomass combustion was studied using a thermogravimetric analyzer (TGA). Effects of potassium salt types (KCl, KCO and KSO), loading concentrations (0, 1, 3, 5, 8 wt%), replacing N by CO, and O concentrations (5, 20, 30 vol%) on the catalysis degree were discussed. The comparison between TG-DTG curves of biomass combustion before and after water washing in both the 20%O/80%N and 20%O/80%CO atmospheres indicates that the water-soluble minerals in biomass play a role in promoting the devolatilization and accelerating the char-oxidation; and the replacement of N by CO inhibits the devolatilization and char-oxidation processes during oxy-biomass combustion. In the devolatilization stage, the catalysis degree of potassium monotonously increases with the increase of potassium salt loaded concentration. The catalysis degree order of the studied potassium salts is KCO > KCl > KSO. In the char-oxidation stage, with the increase of loading concentration the three kinds of potassium salts present inconsistent change tendencies of the catalysis degree. In the studied loading concentrations from 0 to 8 wt%, there is an optimal loading concentration for KCl and KCO, at 3 and 5 wt%, respectively; while for KSO, the catalysis degree on char-oxidation monotonically increases with the loading potassium concentration. For most studied conditions, regardless of the potassium salt types or the loading concentrations or the combustion stages, the catalysis degree in the O/CO atmosphere is stronger than that in the O/N atmosphere. The catalysis degree is also affected by the O concentrations, and the lowest catalysis degree is generally around 20 vol% O concentration. The kinetic parameters under the different studied conditions are finally obtained.
生物质在富氧条件下燃烧（Oxy-biomass combustion）是实现负 CO 排放的方法之一。KCl、KCO 和 KSO 作为生物质灰分中的主要钾物种，可以催化生物质燃烧。本文使用热重分析仪（TGA）研究了代表性钾盐对富氧生物质燃烧的催化作用。讨论了钾盐类型（KCl、KCO 和 KSO）、负载浓度（0、1、3、5、8 wt%）、用 CO 替代 N 和 O 浓度（5、20、30 vol%）对催化程度的影响。在 20%O/80%N 和 20%O/80%CO 气氛中，生物质燃烧前后水洗的 TG-DTG 曲线比较表明，生物质中的水溶性矿物质在促进挥发分脱除和加速焦氧化方面发挥作用；用 CO 替代 N 会抑制富氧生物质燃烧过程中的挥发分脱除和焦氧化过程。在挥发分脱除阶段，随着钾盐负载浓度的增加，催化程度单调增加。研究钾盐的催化程度顺序为 KCO>KCl>KSO。在焦氧化阶段，随着负载浓度的增加，三种钾盐的催化程度呈现出不一致的变化趋势。在所研究的负载浓度从 0 到 8 wt%范围内，KCl 和 KCO 分别在 3 和 5 wt%时存在最佳负载浓度；而对于 KSO，焦氧化过程的催化程度随负载钾浓度的增加而单调增加。对于大多数研究条件，无论钾盐类型、负载浓度还是燃烧阶段，O/CO 气氛中的催化程度均强于 O/N 气氛。催化程度还受到 O 浓度的影响，最低催化程度通常在 20 vol% O 浓度左右。最后得到了不同研究条件下的动力学参数。
