| In this paper, combined with the test on the microstructure strength, structural strength, particle coke reactivity, pore structure, morphology and microcrystalline structure for coke produced from top-charging battery and stamp-charging battery,high-temperature reaction kinetics of coke was studied under different atmosphere and mineral catalysis by using Cahn Thermax700 Thermo Gravity Analysis(TGA),The results showed that:(1) The microstructure strength and structural strength of coke produced from top-charging battery was 62.9% and 94.1% respectively, its porosity was 27.21%, its content of isotropy, fusain and fragments was 28.1%. The microstructure strength and structural strength of coke made with stamp-charging battery was 60.7% and 93.8%respectively, its porosity was 25.81%, its content of isotropy, fusain and fragments was 47.1%.(2) Adsorbing soluble salts containing Sodium(Na), Ferrum(Fe) and Calcium(Ca)could have positive effect on the particle reactivity of coke, with the concentration increased, such effect increased. While Boric acid(H3BO3) had negative effect on the particle reactivity of coke. After high temperature reaction, the number of diffraction peak and graphitization degree of minerals-adsorption coke increased; the surface morphology changed obviously from “smooth, uniform†into “roughâ€, pores from small and shallow holes into large and deep holes, and the number of the micro-holes increased, the phenomenon of perforation and coalescence was obvious.(3) At the same heating rate, the change trend of the carbon conversion and reaction rate of coke made with top-charging battery under the condition of different particle size and reaction atmosphere was similar to that of coke produced from stamp-charging battery, generally speaking, the carbon conversion rate increased gradually with the increase of reaction temperature, after 1500℃ it became stable, at this point, the corresponding reaction rate was normally distributed. According to the calculation, the kinetic model of low-temperature period(9500℃-1100℃) was a one-dimensional diffusion model, of intermediate-temperature period(1100℃-1350℃) was a two-dimensional one and of the high-temperature period(1350 ℃-1600 ℃) was a three-dimensional spherically symmetric one. The order of activation energy index(E) and pre-exponential factor(A) for different temperature periods was: the intermediate-temperature period > the low-temperature period > the high-temperature period, and the E value of coke made with top-charging battery was higher. As the atmosphere changed to the mixed gas of CO, CO2 and N2, such order was: the low-temperature period > the intermediate-temperature period > the high-temperature period.(4) The coal conversion of coke adsorbing the soluble salts containing Na, Fe, Ca exhibited increasing trend, its initial reaction temperature, the sharp reaction temperature and values of E and A decreased, and obvious decrease of these parameters can be seen with the increase of catalyst content. The increase rate of the carbon conversion rate for coke made with stamp-charging battery was larger,indicating that the coke made with top-charging battery has better alkali-resistance performance; However, after adsorbing H3BO3, these parameters increased, and values of E and A increased more obviously with the increase of catalyst content.(5) The results showed that according to the kinetics of solution loss reaction of coke,in the low-temperature period, the solution loss reaction rate was low, the block of coke reduced slightly, and the structure was relatively unchanged; In the intermediate-temperature period, the solution loss reaction rate of coke increased significantly, the damage of coke structure is relatively serious and the block of coke was smaller; In the high-temperature period, the solution loss reaction rate of coke was close to the low-temperature period, but the number of active molecules of coke surface increased, at this time, the solution loss reactionof coke is given priority to the surface, the surface pulverization was more serious, the block of coke further reduced until the pulverization. The existence of minerals have positive effect on the solution loss reaction of coke, the positive effect could be thought as the decrease of the solution loss reaction activation energy and the increase of the number of the active intermedias(the planar-semiquinone complexes containing oxygen Cf(O)and the non-planar complexes containing oxygen C(O)Cf), the negative effect could be regarded as the increase of the solution loss reaction activation energy and the inhibition of the formation of the active intermedias. |
