Search | Engineering

资源类型

期刊论文 2

年份

2021 2

关键词

检索范围：

排序：展示方式：

Effect of oil shale semi-coke on deposit mineralogy and morphology in the flue path of a CFB burning Zhundonglignite

Zhuo LIU, Jianbo LI, Mingming ZHU, Xiaofeng LU, Zhezi ZHANG, Dongke ZHANG

《能源前沿（英文）》 2021年第15卷第1期页码 26-37 doi: 10.1007/s11708-020-0668-1

摘要： The effect of oil shale semi-coke (SC) on the mineralogy and morphology of the ash deposited on probes situated in the flue path of a circulating fluidized bed (CFB) which burns Zhundong lignite (ZD) was investigated. 10 wt% or 20 wt% SC was added to ZD, which were then combusted in the CFB furnace at 950°C. Two probes with vertical and horizontal orientations were installed in the flue duct to simulate ash deposition. Both windward and leeward ash deposits on probes (P W, P L, P W and P L) were analyzed by using a scanning electron microscopy with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), an inductively coupled plasma optical emission spectrometry ICP-OES, and a particle size analyzer. When ZD was burned alone, the P W deposit was comprised of agglomerates (<30 m) enriched in CaSO and Na SiO , incurring significant sintering. The P L and P W deposits, however, were of both discrete and agglomerated particles in similar mineral phases but with coarser sizes. The P L deposit was mainly fine ash particles where Na SiO and Na SO were absent. As SC was added, the agglomerates in both P W and P L decreased. Moreover, SiO and Ca/Na aluminosilicates dominated the mineral phases whereas Na SiO and Na SO disappeared, showing a decrease in deposit stickiness. Likewise, the P W deposit was found less spread on the probe, decreasing its deposition propensity. Na-bearing minerals turned into (Na, K)(Si Al)O and (Ca, Na)(Si, Al) O in the P W deposit. Moreover, Na in the deposits decreased from 32 mg/g to less than 15 mg/g as SC presented. The addition of SC would therefore help alleviate the propensity of ash deposition in the flue path in the CFB combustion of ZD.

关键词： ash deposition circulating fluidized bed (CFB) mineral transformation oil shale semi-coke (SC) Zhundong lignite (ZD)

HTML PDF 收藏

Reaction kinetics and internal diffusion of Zhundong char gasification with CO

Yun Liu, Jiangyuan Qu, Xuehui Wu, Kai Zhang, Yuan Zhang

《化学科学与工程前沿（英文）》 2021年第15卷第2期页码 373-383 doi: 10.1007/s11705-020-1949-2

摘要： Mass transfer usually affects the rate of chemical reactions in coal. The effect of internal diffusion on char gasification with CO in the temperature range from 1123 K to 1273 K was investigated via thermo-gravimetric analysis and assessment of char morphology features. The results revealed that the effect of internal diffusion on the initial reaction rate was more significant with an increase of particle size, due to the concentration gradient of the gasification agent within the solid particles. In the early stage of gasification, the generation of new micropores and the opening of closed pores led to an increase in specific surface area. As the reaction proceeded, the openings were gradually expanded and the specific surface area continued to increase. However, with further reaction, disappearance of edge pores, melting and collapse of the pore structure led to a decrease in specific surface area. The intrinsic activation energy and reaction order based on the th-order model were 157.67 kJ∙mol and 0.36, respectively. Thus, temperature zones corresponding to chemical reaction and diffusion control were identified. Moreover, the calculated effectiveness factor provided a quantitative estimation of internal diffusion in the initial stage.

关键词： coal char CO₂ gasification internal diffusion pore evolution