Chemical structure analysis and fast micro-pyrolysis study of hydrochar derived from hydrothermal treatment of municipal solid waste.

Hydrothermal treatment (HTT) experiments were conducted at 210○C and 230○C with 30, 60 and 90 min residence times. Fourier transform infrared spectroscopy (FT-IR) and 13C solid-state nuclear magnetic resonance (NMR) were employed to elucidate the effect of HTT on the chemical structure of municipal solid waste. FT-IR results clearly demonstrate that decarboxylation and aromatization reactions occurred during HTT. Fewer types of carbon skeleton structures were observed in the 13C solid-state NMR of hydrochars. The aliphaticity yield increased from 74.84% to 91.57% with increasing experiment parameters. In addition, the aromatization reaction was more dramatic in the early stage time, while carbonyl compounds decomposed during the HTT process. Pyrolysis gas chromatography mass spectrometry analysis showed that HTT had positive effects on the simplification of the pyrolytic gas component. In addition, all hydrochars were significantly inhibited to the formation of aromatic compounds with a minor relative peak area of 19.89%. Moreover, hydrochars obtained at a relatively low temperature could achieve a higher yield of hydrocarbons, and hydrocarbons could be partly purified after the HTT process. Overall, the available values of fast pyrolysis products were upgraded by the HTT process.

Research on the Diagenetic Facies Division and Pore Structure Characteristics of the Chang 63 Member in the Huaqing Oilfield, Ordos Basin.

In tight sandstone reservoirs, diagenesis has a significant impact on the development of reservoirs and pore structures. To clarify the effect of diagenesis on the pore structure of tight sandstone, 12 samples of the Yanchang Formation in the basin were studied based on experiments such as high-pressure mercury intrusion and low-temperature nitrogen adsorption. The diagenetic facies in the study area are divided into two categories: strong cementation facies of carbonate minerals and strong compaction facies of soft component minerals, which are relatively unfavorable diagenetic facies, and stable facies of felsic minerals and strong dissolution facies of feldspar minerals, which are dominant diagenetic facies. The pore structure of the Chang 63 reservoir in the study area has obvious fractal characteristics, with a fractal dimension D 1 greater than D 2 and a greater heterogeneity of large pore throats. Compared to compaction and cementation, dissolution has a stronger controlling effect on the pore structure of reservoirs. In tight sandstone reservoirs with low porosity and permeability, dissolution has a more important impact on reservoir transformation and development. The intensity of different types of diagenesis in the Chang 63 reservoir affects reservoir heterogeneity, and the level of the reservoir heterogeneity affects the complexity of reservoir pore structure. In tight sandstone reservoirs, cementation has a stronger controlling effect on the structural complexity of large pores, while dissolution has a stronger controlling effect on the structural complexity of small pores. The dissolution has a strong control effect on the physical properties of the reservoir. This study provides insights into the relationships among the diagenetic facies, reservoir quality, and pore structure of tight sandstone reservoirs. This study has reference significance for the exploration and development of tight oil in the research area.

Thermal behavior and general distributed activation energy model kinetics of Lignite-Chinese herb residues blends during co-pyrolysis.

In this work, the pyrolysis behavior of lignite, Chinese herb residues (CHR) and their blends were explored by thermogravimetric analysis. The co-pyrolysis improved the pyrolysis characteristic of lignite, leading to an increment of index D. Analysis results showed that 30%-50% of CHR add ratio was the appropriate choice for co-pyrolysis with lignite. It was clarified that synergetic effects between lignite with CHR occurred during the co-pyrolysis treatment. And the promoting effects were dominated at 240 °C to 310 °C, while it turned to inhibiting effects at 315 °C to 355 °C. The pyrolysis kinetic evolution was adapted by a new general distributed activation energy model with four pseudo-components. The simulation results demonstrated an excellent match with the adjusted coefficients Radj2 over 99.97%. In addition, G-DAEM further considered A-E kinetic compensatory effect. The outcomes enriched the applicability of this model in thermal process of other fuels.