ABSTRACT
Paraffin base crude oils often contain paraffin wax that is composed of paraffin hydrocarbon derivatives (from C18 to C36) and naphthene hydrocarbon derivatives (from C30 to C60). The hydrocarbon constituents of wax can be present in several phases, as gas, liquid, or solid particles depending on the flow parameters of pressure and temperature. In addition, the naphthene hydrocarbon derivatives that may comprise paraffin base crude oils are known as microcrystalline wax. As a means of differentiation, macrocrystalline wax generally leads to paraffin problems in production and transport operations, whereas microcrystalline waxes contribute to tank-bottom sludge.
This chapter presents descriptions of the various methods of removing (dewaxing) crude oil and refinery products such as (1) solvent dewaxing, which can be applied to light, intermediate, and heavy lubricating oil distillates; (2) catalytic dewaxing, a selective hydrocracking process; and (3) urea dewaxing, which offers a viable means of segregating the wax constituents during the dewaxing process.
