No abstract

No abstract

No abstract

Coal coprocessing can be done either in a single-stage or in a multistage process. It has been found that multistage processing offers some advantages over single-stage processing. In this study, a two-stage process was selected for coal liquefaction. In the first stage (solvent production stage), the waste materials were liquefied at milder conditions to obtain a suitable solvent for the coal liquefaction. In the second stage, the liquid product obtained from the first stage was used as solvent for coal. The two-stage liquefaction process was carried out in the absence of externally added catalysts. The reactions were carried out in a tubing bomb microreactor at temperatures of 350-450°C and 1250 psig of cold hydrogen pressure for reaction times of 15-120 min at 10% coal loading. Total conversion, and conversion to asphaltenes, oils, etc., were monitored. A model for coal liquefaction has been developed as part of this study. A rigorous parameter estimation method was used to estimate the model parameters. The predictions for the coal conversions were found to be within (3% of the observed values. Total conversion as high as 99% and oil conversion up to 90% were obtained in two-stage processing. Two-stage processing leads to higher coal conversion and oil yield compared to single-stage processing. The model parameters for the single-stage and two-stage processes were compared.

Coprocessing of coal with a petroleum waste containing grease in waste oil was studied. Experimental parameters such as temperature, pressure, reaction time, coal loading, and grease loading in the system were examined. Coal conversions were found to increase with temperature, hydrogen pressure, reaction time, and coal loading. Coal conversions in excess of 90% were obtained during coprocessing, with conversions to oil of over 50%. At a fixed coal loading, the presence of a higher amount of grease in the system was found to increase the conversion of coal. This can be explained as due to the catalytic action of the heavy metals such as molybdenum in the grease during coprocessing. The high aromaticity of waste grease made it a good solvent for coal liquefaction. The waste oil and waste grease were demetalized during coprocessing, and the viscosity of the oil was reduced.