DELAYED COKING - INDUSTRIAL AND LABORATORY ASPECTS

Delayed coking is a thermal process to convert petroleum residues to a solid coke material. Processes occurring in a delayed coker are compl icated and attempts have been made, at the laboratory level, to simula te industrial delayed coking. Although the latter studies are useful, it is impossible to scale-down to the laboratory level. Industrial del ayed coking is a turbulent process and such movements cannot be simula ted easily in the laboratory. Of industrial importance are the multiph ase systems, i.e. volumes of unreacted isotropic pitch residue, transp orted through the bulk, fluid anisotropic mesophase, so creating order ing into acicular structures in the vicinity of the multiphase systems . Four petroleum residues were analysed chemically. Pyrolyses were car ried out under pressures of up to 1.0 MPa. Complete mass balances were obtained and the semicokes examined by optical microscopy. Feedstocks for delayed cokers can be blends of petroleum residues, some of which can produce considerable amounts of volatile materials. Volatile evol ution, at the optimum operating condition of the delayed coker, can br ing about improvements in resultant coke quality. In industrial delaye d coking it is important not only to consider the chemistry of the fee dstocks, but attention must also be given to the physico-chemical aspe cts of coker operation. (C) 1997 Elsevier Science Ltd.