Analysis of sludges from benzole recovery plants using petroleum oils

Abstract

An account is given of an investigation of the composition of sludges from petroleum oils used for recovering benzole at coke‐oven and gas works. This investigation was carried out by the National Benzole Association for the Benzole Technical Committee of the Ministry of Fuel and Power and forms part of the programme of work carried out during the war by that committee on the sludging of petroleum oils, with a view to reducing the consequent loss of crude benzoic. A more complete knowledge of the nature of the solid material contained in the sludges, it was hoped, would give some clue as to its source, and the causes of its formation. For full details of the investigation on sludging, the Report of the Benzole Technical Committee should be consulted.* The material, called deposit, obtained from the sludges after removal of oil and water was extracted selectively with organic solvents. A detailed examination of the deposits and their extracts showed that they were extremely complex in character and that no separation into material of substantially simpler character had been effected. Ultimate analyses showed that all the deposits contained carbon, hydrogen, oxygen, nitrogen, sulphur, and usually iron. Oxygen %vas usually high in amount (5·5% to 36·7%), depending apparently on the extent to which the sludges had been subjected to heat in the plant, and suggesting that the deposits are oxidation and condensation products, rather than polymers of unsaturated compounds. No evidence was obtained that the deposits or extracts contained nitrogenous gum or its heat‐degradation products.