Alternative treatment of petroleum waste via thermochemical conversion

The petroleum industry generates significant amounts of waste in the form of drill cuttings, contaminated soil and oily sludge. Drill cuttings are a product of the off-shore drilling rigs, containing wet soil and total petroleum hydrocarbons (TPH). Contaminated soil comes from different on-shore sites and also contains TPH. The oily sludge is mainly residue or tank bottom sludge from storage tanks. The two main treatment methods currently used are incineration and thermal desorption (TD). Thermal desorption is a method where the waste material is heated in an anaerobic environment to release volatiles, the condensed volatiles can be used as a liquid fuel. For the thermal desorption unit dry contaminated soil is mixed with moist drill cuttings to generate a suitable mixture. TD-feedstock material has been thermo gravimetric analyzed (TGA) to find the proximate analysis, a bomb calorimeter is used to find the higher heating value (HHV) of the material. Ultimate analysis is performed with a CHNS-O flash analyzer. The results of these analyses are used to model co-gasification of TD-feedstock with tires. The Gibbs energy minimization method together with Lagrange Multiplier are used in a zero-dimensional model. TD-feedstock/tire mixture was varied as well as the air/fuel ratio. It was found that a minimum of 40wt% tires is required for gasification. The maximum temperature, i.e. stoichiometry, was reached at an air/fuel ratio of 1.2 for all mixtures.