Effect of Flue Dust on the Vanadium Oxide Catalyst Utilized by the Contact Oxidation Process

Abstract

Concepts for controlling SO₂ from fossil fuels can be separated into two main categories: (1) Residual and vacuum gas oil desulfurization and (2) Flue gas desulfurization. The Kiyoura-T.I.T. process confines itself to the desulfurization of flue gas. It employs vandium oxide as a catalyst which oxidizes the sulfur dioxide to trioxide, followed by a gaseous phase reaction of ammonia. The end product, ammonium sulfate is removed by an electrostatic precipitator. (The details were presented at annual meetings of APCA in 1966 and 1967 as 1 and II.) Flue gas is passed through cyclone and dust filter to remove dust. Under normal operating conditions almost all of the dust is removed at the filters. The author carried out experiments to determine whether there was any effect on the activity of the catalyst, assuming that a portion of the dust escapes into the stream along the flue. It has been generally accepted that in fuel oil firing steam power plants, about 100 mg./nm³ of dust including carbon, hydrocarbon, and ash are normally contained in the flue stream. The carbon and hydrocarbon is oxidized readily at the filters and exists only as ash. An amount of ash equivalent to the amount assumed to have settled on the catalyst over a period of 3–12 months, was placed on the catalyst, and experiments were carried out. The SO₂ conversion efficiency was measured and found to be over 93%. The results showed that at the actual operational temperature of 450°C, ash had practically no effect at all.