Pyrolysis of oil sludge with additives of sodium and potassium compounds

Abstract

Previous efforts were made to convert the oil sludge into useful resources such as lower molecule organic compounds and carbonaceous residues by pyrolysis with the carrier gas of N 2. In the present study, the oil sludge from the oil storage tank of a typical petroleum refinery plant located in the northern Taiwan was used as the raw material of pyrolysis. The influences of using sodium and potassium compounds as additives on the possible improvement of the pyrolysis of oil sludge are investigated. The additives employed include two groups: (1) sodium compounds (NaOH, NaCl and Na 2CO 3), and (2) potassium compounds (KCl, KOH and K 2CO 3). For the increases of conversion, the additives provide the offers in the order of K 2CO 3>KOH>NaOH>Na 2CO 3>KCl>NaCl>no additives. It appears that the above additives enhance the reaction rates when the temperatures are in 650–710 K, following the orders NaOH>Na 2CO 3>NaCl>no additives, and K 2CO 3>KOH>KCl>no additives. The additives achieve the improvement of the quality of pyrolysis oil (as sum of light and heavy naphtha and light gas oil) in the order of KOH>KCl>K 2CO 3>NaOH>Na 2CO 3>NaCl>no additives. Nevertheless, the additives improve the liquid yields in the order of KCl>Na 2CO 3>NaCl>no additives>NaOH>K 2CO 3>KOH. All this information is useful not only to the improvement of a pyrolysis system but also to the better utilization of liquid oil products.