Basic Research On New Coal Pyrolisis Process At Lower Remperature With Oxygen-enriched Combustion

Our country nowadays has reserved abundant highly volatile non-coking coal resources. They can generate highly-reactive semi-coke, tar and coal gas products,which can be an efficient method to realize a clean utilization of these coal resources.Tar production from low-temperature carbonization of coal and the semi-coke industry have already been the pillar industries of north of Shaanxi. Aiming at the main problems existing in the current crafts of low-temperature carbonization, namely that the coal gas is in a large quantity but a low quality, it’s hard to be utilized, the moisture content of product is relatively high, the water consumption is high and the quality of product is influenced, a solution centered in the oxygen-enriched technique and cooled coal gas circulation dry quenching is proposed. This article mainly under the condition of rich oxygen carbonization shanbei low metamorphic coal pyrolysis characteristics and kinetics of coal, grain size, heating rate of coal low temperature pyrolysis and the law of the influence of different yield of pyrolysis carbonization media, and studies the volatilization characteristic of coal pyrolyzed gas.A conventional pyrolysis and pyrolytic kinetics analysis were made on three kinds of coal samples. The result shows that,with the increase of heating rate, the DTG curve peak after the first reduce the rising trend of DTG peak, the higher the heating rate, the slower the reaction rate at the same temperature. Two phases of pyrolytic process respectively match the reaction order mode and thethree-dimensional diffusion model, the pyrolytic reaction activity sequence of these coals is SJC coal> WJG coal> JFG coal. Show that SJC coal pyrolysis reactivity is highest, followed by WJG coal, coal pyrolysis JFG lowest reactivity, which consistent with the volatile characteristic index of the Rv results.Using thermal mass combination（TG-MS） experiment investigated the different heating rate under the condition of main coal pyrolysis gases and vapors features（CH₄, H₂, CO, CO₂ and H₂ O, C_nH_m） and its kinetic parameters. The result indicates that the exhalation rate of coal gas increases with heating rate within a certain range of heating rate and the temperature corresponding to the maximum escape quantity decreases with the heating rate; utilize the Malek method to calculate the kinetic parameter of gas volatilization and it shows that the volatilization of C2H₂ and H₂ meets the chemical reaction model（n=2）; a peak-separation calculation method was carried out on CO₂ and CO liberated from coal pyrolysis and the second and third peaks of CO₂ are both relatively accord with the three-dimensional diffusion; the first peak of CO₂ is accord with the equation of JMA; but all the three peaks of CO are accord with the three-dimensional diffusion. f（α） function is figured out by the S-B model formula. The degasification mechanism function of CH₄ is f（α）= α0.78（1-α）0.47;the degasification mechanism function of H₂ O is f（α）= α0.72（1-α）0.36.Through the evolution of the conversion method to calculate the gas such as activation energy and refers to the former factor.A low temperature pyrolysis experiment in different gases was performed by using the self-developed experimental facility for pyrolysis weighing 250 g. The result indicates that the granularity has a relatively small influence on the product yield of low temperature pyrolysis of coal in the gas of N2. The decrease of granularity results in a decrease of the yield of semi-coke and an increase of yields of liquid and gaseous products.By the low temperature pyrolysis experiment with different retorting gas proportion, it’s concluded that the methane and the hydrogen can develop the yield of tar in a low temperature. At the same time, all the three gases can decrease the yield of semi-coke and increase the yield of coal gas. In H₂,CH₄ and CO, the low temperature pyrolysis can promote the precipitation of maincomponents in the coal gas. And with the increase of proportion of pyrolysis medium gas, concentrations of main components in the coal gas are correspondingly increased.In H₂, CH₄ and CO, the low temperature pyrolysis of coal can enhance the quality of tar. And the portion of light tar increases with the gas proportion. The maximum tar yield in the 60% proportion of H₂ is 10.69%, the yield of semi-coke is72.88% and the yield of coal gas is 12.64%; the maximum tar yield in the 30%proportion of CH₄ is 8.96%, the yield of semi-coke is 74.56% and the yield of coal gas is 11.48%.the maximum tar yield in the 30% proportion of CO is 9.24%, the yield of semi-coke is 75.08% and the yield of coal gas is 10.68%.