Research On Pore Wettability And Imbibition Ability In Stacking Bed Of Pulverized Coal

Pulverized coal has been used more widely instead of traditional coal.During the storage and transportation of coal,smoldering fires are easily generated because of physicochemical reactions which make inside temperature rise to ignition point.How to deal with pulverized coal smoldering fires quickly is an important problem about protecting public security.Water-based extinguishant is one of the main smoldering fires extinguishants due to its many advantages.But coal particle's strong hydrophobicity makes water hardly flow inside and reaching the ignition point.Thus,pulverized coal from Datong,Shanxi was taken as the research sample to study the pore wettability and imbibition ability of stacking bed in pulverized coal with different additives.This paper is aimed at improving transporting performance of water-based extinguishant in pulverized coal bed and making water flow inside quickly to put out smoldering fires.First,the physical properties of pulverized coal were measured.It was found that the particles'average grain size was 3.537?m,which belongs to ultrafine pulverized coal.The fine particles could plug pores and affect the process of permeation.The result of FTIR showed that there were many non-polar groups such as aliphatic and aromatic hydrocarbons on the surface of pulverized coal,leading to strong hydrophobicity.There existed some oxygenic groups as well,making pulverized coal appear electronegative in solutions,which was consistent with the results of zeta potential.Through pore structure analysis it was found that the mean pore volume was 0.036 cm~3/g and the mean specific surface area was 14.273 m~2/g,which were mainly microporous and mesoporous structures.According to the physical measurement results of pulverized coal,hexadecyl trimethyl ammonium bromide(CTAB),sodium dodecyl benzene sulfonate(SDBS),sodium dodecyl sulfate(SDS),dioctyl sulfosuccinate sodium salt(DOSS),titanyl sulfate(OP-10)and polyethylene glycol 4000(PEG4000)were selected to conduct experiments in this paper.The wettability was represented by dynamic contact angles of water on coal surface.The influence of surfactants'kind and concentration were studied.Wetting mechanism was analyzed on basis of surface tension and zeta potential.In addition,a dynamic wetting model was built to describe the wetting process and evaluate the wetting effect.It was found that DOSS solution with a concentration of0.10 wt%showed the best wettability for pulverized coal because of its low surface tension and strong adsorption on coal surface.Then the imbibition law of solutions in pulverized coal was studied continuously by setting up self-made experiment apparatus.And the imbibition height and imbibition rate were measured to analyze the imbibition effect.The influence of coal particle size,bulk compactness,and solution properties was researched according to capillary theory,which could provide theoretical basis for the application of water-based extinguishant in pulverized coal smoldering fires.