耦合TiO_(2)直接苛化的黑液半焦与石油焦水蒸气共气化特性研究

Steam co-gasification characteristics of black liquor char and petroleum coke coupled with TiO_(2) direct causticization

以黑液半焦(BLC)-苛化剂(TiO_(2))-石油焦(PC)三元混合物(BTP)为研究对象,借助热重分析仪和固定床反应器在850℃进行了恒温水蒸气气化实验,从反应速率、产气特性和残余固体特性等方面探究了耦合TiO_(2)直接苛化的BLC和PC共气化过程。结果表明,源于m Na_(2)O·n TiO_(2)对有机碳气化反应的促进作用,与单独的TiO_(2)直接苛化BLC气化和PC气化加权平均(BTP_(theo))相比,耦合共气化过程表现出显著的协同效应。BTP最大反应速率达到7.0%/min,为BTPtheo的2.9倍;BTP产气中有效气组分(H_(2)+CO)的含量及其产率分别为81.1%和2059 mL/g,气体热值为9343 kJ/m^(3),相对于BTPtheo分别提高6.8%、137.3%和5.5%;BTP的碳转化率和能源输出比分别为95.0%和1.13,相比BTPtheo,分别提高61.6%和135.4%。此外,BTP在气化过程中的无机盐损失得到有效控制,相对损失率约9.4%;BTP残余固体中的Na盐以高热稳定性的m Na_(2)O·n TiO_(2)为主,并保持颗粒状,有利于后续的碱回收。

The isothermal steam gasification experiments of a ternary mixture(BTP) containing black liquor char(BLC), causticizing agent(TiO_(2)), and petroleum coke(PC) were carried out at 850 ℃ based on a thermogravimetric analyzer(TGA) and a horizontal fixed-bed reactor. A co-gasification process of BLC and PC coupled with TiO_(2)direct causticization was explored from the aspect of reaction rate as well as the characteristics of gaseous products and gasification residues(GR). The results show that in comparison to the weighted average(BTPtheo) of the independent gasification of TiO_(2)direct causticized BLC and PC, significant synergistic effects could be aroused during the coupled co-gasification process due to promoting action of m Na_(2)O·n TiO_(2)on gasification of organic carbon. Specifically, the maximum reaction rate of BTP reaches 7.0%/min, which is 2.9 times that of BTPtheo. The content and yield of effective gas components, i.e., H_(2)+CO, in the gas products, as well as its lower heating value(LHV) of BTP are 81.1%, 2059 mL/g, and 9343 kJ/m^(3), respectively, which is 6.8%, 137.3%, and 5.5% higher than that of BTP_(theo). The carbon conversion and energy output ratio of BTP reaches 95.0% and 1.13, respectively, which is increased by 61.6% and 135.4% relative to the theoretical superposition value. In addition, the relative loss of inorganic salts in BTP during the whole thermochemical conversion process is effectively controlled at a lower level of about 9.4%. Since the Na-containing salts in GR of BTP are mainly m Na_(2)O·n TiO_(2)with higher thermal stability,and GR maintains good particle flowability, it is conducive to downstream alkali recovery.