Effects of alkali metal on solution loss and coke degradation

Abstract

To research the effect of alkali metals on the solution-loss rate and coke strength after reaction, potassium and sodium vapors were prepared by a high-temperature thermal-reduction method, and the thermal properties of four industrial cokes that absorbed potassium and sodium vapor were studied. The thermal properties include the traditional thermal-property indices, coke reactive index and coke strength after reaction, and the coke strength after a 25% mass loss, which is obtained by a continuous thermogravimetric test. Results show that because of the different adsorption mode, the catalytic effect of potassium and sodium is different. During the early stages of the solution-loss reaction, the reaction rate of the potassium-rich coke is higher than that of the sodium-rich coke, but the reaction rate decreases rapidly. The reaction rate of the sodium-rich coke in the later stage of the reaction is higher than that of the potassium-rich coke. The coke strength after reaction of the alkali-rich coke is low, mainly because of the high carbon-solution loss. The coke strength after the 25% mass loss of potassium-rich coke was higher than that of the original coke because the solution reaction was closer to the surface reaction.