Changes in properties of tar obtained during underground coal gasification process

Abstract

In this study, the composition of tars collected during a six-day underground coal gasification (UCG) test at the experimental mine ‘Barbara’ in Poland in 2013 was examined. During the test, tar samples were taken every day from the liquid product separator and analysed by the methods used for testing properties of typical coke oven (coal) tar. The obtained results were compared with each other and with the data for coal tar. As gasification progressed, a decreasing trend in the water content and an increasing trend in the ash content were observed. The tars tested were characterized by large changes in the residue after coking and content of parts insoluble in toluene and by smaller fluctuations in the content of parts insoluble in quinoline. All tested samples were characterized by very high distillation losses, while for samples starting from the third day of gasification, a clear decrease in losses was visible. A chromatographic analysis showed that there were no major differences in composition between the tested tars and that none of the tar had a dominant component such as naphthalene in coal tar. The content of polycyclic aromatic hydrocarbons (PAHs) in UCG tars is several times lower than that in coal tar. No light monoaromatic hydrocarbons (benzene, toluene, ethylbenzene and xylenes—BTEX) were found in the analysed tars, which results from the fact that these compounds, due to their high volatility, did not separate from the process gas in the liquid product separator.

Characteristics and Evolution Mechanism of Three Phase Products of Lignite by Hydrothermal Treatment Dewatering

“…Therefore, HTD effectively improves the downstream application of coal with a high alkali metal content. 21 On the other hand, the alkaline earth metal cation concentrations of Mg 2+ and Ca 2+ increased from 55.52 mg/L and 53.52 mg/L in HTD150 to 151.08 mg/L and 742.60 mg/L in HTD310, indicating that the hydrothermal modification was also effective in the removal of alkaline earth metals in lignite. The removal of alkaline earth metals can effectively reduce pipeline scaling problems in downstream applications.…”

“…The removal effect of alkali metal was significant, and the removal of alkali metal could effectively improve the corrosion and slagging of lignite in the later application process. Therefore, HTD effectively improves the downstream application of coal with a high alkali metal content . On the other hand, the alkaline earth metal cation concentrations of Mg 2+ and Ca 2+ increased from 55.52 mg/L and 53.52 mg/L in HTD150 to 151.08 mg/L and 742.60 mg/L in HTD310, indicating that the hydrothermal modification was also effective in the removal of alkaline earth metals in lignite.…”

Research on creep-fatigue model of anchored jointed rock mass

“…With in large-scale strategic engineering of deep rock mass in China, ensuring stability of a deep rock mass structure and preventing catastrophes have become the first priority. The existing research shows: Deep rock mass has obvious rheological characteristics, and it is very easy to aggravate its rheological state due to blasting, earthquake and other disturbances, thus causing instability and failure of deep rock mass (Feng et al, 2022;Wiatowski et al, 2021). Therefore, the influence of load on deep rock masses cannot be ignored.…”

Study on the shear creep characteristics of anchored jointed rock masses under creep fatigue loading

“…The engineering geological conditions of deep jointed rock masses are extremely complex, and the mechanical interaction between bolts and jointed rock masses is difficult to accurately grasp, which leads to deformation and instability of jointed rock masses. With the construction of large-scale strategic projects in deep rock masses in China, safety and stability of underground engineering is of great importance (Feng et al, 2022;Wiatowski et al, 2021). The complex engineering geological environment poses many challenges to the development of underground engineering, in which the influence of load on deep rock masses cannot be ignored (Szkudlarek and Janas, 2021).…”