The process is used for demercaptanization of kerosene and diesel distillates, total sulfur content in which does not exceed a norm. DMD-1 process provides decrease of mercaptan sulfur content in kerosene below 20 ррm.
The process consists in oxidation of mercaptans to disulfides with air oxygen over homogeneous IVKAZ catalyst applied to activated carbon.
Feedstock (kerosene or diesel fuel) is heated in heat exchanger Н-1 to a temperature of 50–80о С and enters reactor R-1. Before the reactor inlet an estimated quantity of air is injected into the feedstock via efficient distributor. Oxidation of mercaptans takes place in the reactor at a temperature of 60–80о С and a pressure of 0.5–1.5 MPa over UVKO catalyst following a reaction:
2RSH + 0.5O2 → RSSR + H2O
The demercaptanized feedstock together with the spent air is discharged from the reactor bottom and sent via air cooler С-1 to settler V-1 to be settled from reaction water, then to salt filter V-2 for moisture removal and to adsorber А-1 for removal of traces of resinous substances. The dissolved air (5–10 % of oxygen and 90–95 % of nitrogen) is separated at pressure reduction in storage tanks of finished products.
The DMD-1 process for aviation kerosene treatment was commissioned on Kuibyshev refinery (capacity of the plant is 310 000 t/yr) and Ukhta refinery (capacity of the plant is 50 000 t/yr).
DMD-1 process flow diagram