Pore structure characterization of different rank coals using gas adsorption and scanning electron microscopy

Macromolecular and pore structures of Chinese tectonically deformed coal studied by atomic force microscopy

Recent experimental advances for understanding bubble-particle attachment in flotation.

Freezing and thawing cycles occur with cyclic liquid nitrogen (LN2) injection in coal. The freeze–thaw treatment damages the pore structure of coal and thus increases its permeability. In this study, NMR and strain monitoring were employed to investigate the changes in coal structure when the coal specimens were under cryogenic treatment using LN2. We classified freeze–thaw process into four stages; stages I and III are dominated by seepage pore development, and stages II and IV are dominated by adsorption pore development. It was found that LN2 freeze–thaw cycles can cause structural deterioration in the coal so as to improve both fracture density and overall permeability. The results demonstrate that the rate of increase of both the effective porosity and total porosity of the coal are positively correlated with the LN2 freezing time and the number of freezing cycles but negatively correlated with the residual porosity. For the same absolute LN2 freezing time, cyclic freeze–thawing has a greater effect ...

Pore Structure in Coal: Pore Evolution after Cryogenic Freezing with Cyclic Liquid Nitrogen Injection and Its Implication on Coalbed Methane Extraction

https://espace.library.uq.edu.au/view/UQ:367798/UQ367798_OA.pdf

Novel integrated techniques of drilling–slotting–separation-sealing for enhanced coal bed methane recovery in underground coal mines

Relationship between macro-fracture density, P-wave velocity, and permeability of coal

As a new technology, Atomil Force Microscopy (AFM) is being used in the research of microscopic structure on coal surface in recent years. By this technology, we can observe the nanoscale pore and crack shape of coal surface, and meas- ure some structural parameters. Different metamorphic grades produce different feature of surface microscopic structure of coal. This paper analyzes the surface microscopic structure of different metamorphic grade coal by AFM. The results show that the coal surface microstructure has a trend from rough to smooth with the increasing of metamorphic grade. The low rank coals contain large or medium pores and the high rank coals contain micro pores. The values of surface morphology characteristic parameters (Sq and Sa) nonlinearly decrease with the increasing coal rank. That is, the coal surface becomes smoother during coalification.

Atomic force microscopy study on microstructure of various ranks of coals

The invention discloses a collecting device for testing a carbon oxidation factor of civil coal-bed gas on line. The collecting device is characterized by comprising a device body which consists of an inner cone and an outer cone and is provided with a clamping wall type cooling cavity (5), wherein a lower port of a hollow conical cavity of the device body is a gas inlet (1), and an upper port of the hollow conical cavity of the device body is a gas outlet (2); a cooling water inlet pipe orifice (3) communicated with the clamping wall type cooling cavity is formed on the lower part of the conical wall of the outer cone of the device body; and a cooling water outlet pipe orifice (4) communicated with the clamping wall type cooling cavity is formed on the upper part of the conical wall of the outer cone of the device body.

Collecting device for testing carbon oxidation factor of civil coal-bed gas on line

The utility model discloses a collecting device for on-line monitoring of civil coal-bed gas carbon oxidization factors. The collecting device is characterized by comprising a device main body which consists of inner and outer tapered barrels and is provided with a clamping wall type cooling cavity (5), wherein a gas inlet (1) is formed at the lower port of a hollow tapered cavity of the device main body; a gas outlet (2) is formed at the upper port of the hollow tapered cavity of the device main body; a cooling water inlet tube port (3) communicating with the clamping wall type cooling cavity is formed at the lower part of the outer tapered barrel wall of the device main body; and a cooling water outlet tube port (4) communicating with the clamping wall type cooling cavity is formed on the upper part of the outer tapered barrel wall of the device main body.

Haitao Zhu

Papers

Macromolecular and pore structures of Chinese tectonically deformed coal studied by atomic force microscopy

Relationship between macro-fracture density, P-wave velocity, and permeability of coal

Atomic force microscopy study on microstructure of various ranks of coals

Collecting device for testing carbon oxidation factor of civil coal-bed gas on line

Collecting device for on-line monitoring of civil coal-bed gas carbon oxidization factors