FUEL
·
2024
·
IF 6.7
Bang Wu,Xin Guo,Xulinjia Liu
The effect of calcium on the synergy evolution mechanism of Zhundong coal and polyethylene (PE) co-pyrolysis was explored by thermogravimetric (TG), fixed-bed experiments, and the ReaxFF simulation method. The weight loss characteristics of coal and PE pyrolysis, obtained through ReaxFF simulations, exhibited good agreement with TG experimental results. The distribution of coal/PE co-pyrolysis products was examined via fixed-bed fast pyrolysis experiments and Reaxff isothermal pyrolysis simulation. The results reveal that calcium substantially reduces co-pyrolysis tar while simultaneously enhancing co-pyrolysis char and gas to varying extents. Besides, the experimental temperature of 973 K and the simulated temperature of 2600 K yield the highest decrease in co-pyrolysis tar, with reductions of 9.52 % and 14.03 %, respectively. It is discovered that the addition of calcium enhances the synergy degree to 100 % between coal and PE molecules, which means that coal molecules become more firmly attached to PE molecular fragments. Additionally, calcium induces polymerization in co-pyrolysis char, causing the char molecules to become larger and increasing their average molecular weight. Ca-containing tars are rich in aliphatic hydrogens, and synergistic molecules prefer light tars, whereas Ca-free tars have a slightly broader range of aromatic hydrogens, and synergistic molecules favor heavy tars, indicating that the addition of calcium may promote the ring-opening process of coal molecules, releasing more branched-chain hydrogen. In the Ca-free and Ca-containing systems, 24.67 % and 29.51 % of the hydrogen content of the coal molecules migrated toward the co-pyrolysis tar, respectively. The proportion of coal tar fragments decreases while the proportion of PE tar and synergistic tar fragments increases in Ca-containing tar when compared to Ca-free tar, indicating that calcium promotes the polymerization of coal tar molecules with PE tar molecules, which leads to larger char molecules and smaller gas molecules.
研究领域:
能源科学
·
化学工程
✓ 已验证
DOI
高影响因子
Energies
·
2024
·Vol. 17
·期 13
·3172
·
IF 3
Maierhaba Abudoureheman,Lanzhen He,Kunpeng Liu,Bo Wei,Jia Lv,Jianjiang Wang,Quan Zhu
The contents of alkali and alkaline earth metals are higher in Zhundong coal, and there are serious problems of slagging and fouling during the combustion process. Therefore, it is of great significance to reveal the mechanism of slagging and fouling in the boiler of Zhundong coal. In this paper, first-principle calculations based on density functional theory are used to study the competition mechanism of alkaline metal oxides during the combustion process in Zhundong coal by establishing the Na2O(110)/CaO(100)-SiO2(100) double-layer interface model. The results show that the bond lengths of the surface of Na2O(110) and CaO(100) with SiO2(100) after adsorption were generally lengthened and the value of bond population became smaller, which formed a stable binding energy during the reaction. The electron loss of Na is 0.05 e, the electron loss of Ca is 0.03 e, and the electron loss of Na2O is greater than that of CaO. The charge transfer on the surface of Na2O with SiO2is obviously higher than that of CaO and the orbital hybridization on the surface of CaO with SiO2is weaker than that on the surfaces of Na2O with SiO2. Na2O is easier to react with SiO2than CaO. The adsorption energies on the surface of Na2O and CaO with SiO2are −5.56 eV and −0.72 eV, respectively. The adsorption energy of Na2O is higher than that of CaO, indicating that Na2O is more prone to adsorption reactions and formation of Na-containing minerals and other minerals, resulting in more serious slagging. In addition, the XRD analyses at different temperatures showed that Na-containing compounds appeared before Ca-containing ones, and the reaction activity of Na2O is stronger than that of CaO in the reaction process. The experimental results have good agreement with the calculation results. This provides strong evidence to reveal the slagging and fouling of Zhundong coal.
研究领域:
能源科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION SCIENCE AND TECHNOLOGY
·
2019
·
IF 1.564
Manda Gao,Yana Feng,Baomin Sun,ZhiZhong Kang,Yifeng Su,Shixing Ding
In this study, the co-combustion of Zhundong coal and NH4H2PO4 was investigated in a laboratory-scale tube furnace. The ash fusibility, combustion performance, and ash characteristics were quantified by experimental approaches. This study also used Gibbs free energy theory to analyze the chemical reactions. The results showed that NH4H2PO4 can extend the burning time of coal and reduce combustion intensity. Moreover, NH4H2PO4 significantly changed the composition of ash, which was caused by reactions between alkali/alkaline earth metals and NH4H2PO4, increasing the sodium retention ratio of the formed ash. In addition, the newly formed phosphate crystals (i.e., Mg2P2O7, AlPO4, and Ca3(PO4)2) with higher melting temperatures contributed to the increase in fusion temperature of the formed ash, and the sodium-containing crystals (i.e., Na2CaP2O7 and NaMg4(PO4)3) contributed to the increase in the sodium retention ratio. Furthermore, NH4H2PO4 had a significant effect on the microcosmic structure, with ash showing more rough and sintering being inhibited.
研究领域:
能源与燃料化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2018
·
IF 3.024
Lian Li,Linyan Zhao,Yixi Wang,Jianning Wu,Guihua Meng,Zhiyong Liu,Jianshu Zhang,Baixing Hu,Qihui He,Xuhong Guo
A novel type of large reticulation, three-dimensional structure of a coal–water slurry dispersant was designed and synthesized, which was mainly used to test the Xinjiang Zhundong coal with abundant reserves and poor slurrying performance. The same types of three dispersants (TIA-1, TIA-2, and TIA-3) were made by adjusting the amount of tannic acid (TA). Commercial NDF dispersant is used for comparison. TA molecules were linked into reticulation by a linker (1,6-dibromohexane) and then modified with 2-acrylanmido-2-methylpropanesulfonic acid and itaconic acid on this reticulated structure. The structure of TIA was confirmed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance. The rheology and stability indicated that the optimal amount of this dispersant was 0.1 wt %, and its pulping concentration was increased to 59 wt %. The dispersants of TIA-1, TIA-2, and TIA-3 comparative tests demonstrated that TIA-1 exhibited excellent stability and rheology, reducing the dosage of the dispersant. The experiment showed that the concentration of slurry could reach 59% with the dosage of 0.1%. This is mainly attributed to the excellent large reticulation, three-dimensional structure of TIA-1. This special structure has polar and nonpolar sites that can efficiently coat coal particles and change the interfacial tension effectively between coal and water.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）