Clean Coke process: process development studies. Report for fourth quarter 1977

Abstract

The carbonization PDU program on West Kentucky coal has been completed. Duplicate material-balance runs with preoxidized West Kentucky coal were conducted, processing coal at 820/sup 0/F and the intermediate semichar at 1400/sup 0/F. Overall accountabilities in the range 98 to 102 percent were obtained on total mass, elemental carbon and sulfur, and on NaOH. Carbonization of West Kentucky coal produced the following yields in weight percent: char (0.75% sulfur)--63.4; tar--11.5; water--4.4; C/sub 1/-to-C/sub 4/ gas--7.8; hydrogen--0.5; acid gas--11.9; and ammonia--0.4. An initial PDU run with highly caking Pittsburgh Seam coal was completed with no agglomeration problem by using fluidizing gas containing 3 percent oxygen in steam. Free-flowing Pittsburgh semichar was produced in a fluid bed at 860/sup 0/F and 24 psia and with a 46-minute residence time. Operating conditions for this run were developed and proven satisfactory in the 3-inch bench-scale carbonizer. Final characterization of tar from carbonization of Illinois coal has been completed. Tar from second-stage carbonization of Illinois semichar in the 3-inch unit was processed and analyzed to identify the type and yield of commercially important components in the chemical-oil fraction. Evaluation of formcoke pellets produced with several types of binder and Illinois char in the coke-preparation PDU indicates that untreated hydrogenation-derived binder yields weaker coke than do binders containing high concentrations of carbonization-derived heavy oil. However, bench studies show that the quality of hydrogenation heavy oil is significantly improved by airblowing for two hours at 300/sup 0/C followed by heat treating for four hours at 380/sup 0/C. Formcoke specimens prepared with the treated binder had an average crushing strength of 10,825 psi, compared with 8375 psi for specimens made with untreated binder.