Research On Reactivity Of High-sodium Coal Thermal Conversion

Zhundong high sodium coal gasification research and its blended coal combustion become increasingly important. In this paper, high sodium with CO₂ coal gasification and coal combustion reactivity are studied experimentally by SDT-Q600 TGA, while with a simplified semi-empirical model analyzing.Firstly, the article considers high sodium coal extraction, de-ash, alkali metal compound sodium load, with SDT-Q600 TGA, it explores the pyrolysis conditions, gas conditions, sodium and high-sodium coal ash and its different components plus the alkali metals sodium affecting high-sodium coal char gasification reactivity with CO₂. There are the following conclusions: what effect CO₂ gasification reactivity of char are final pyrolysis temperature, heating rate pyrolysis and pyrolysis residence time interaction;when the gasification temperature gradually rises, coal gasification reactivity of CO₂ is getting better, but there is a extreme gasification temperature-1150℃, if the temperature exceeds this value gasification, coal gasification reactivity will slow down slightly; The reaction of high-sodium coal char gasification with CO₂ is hindered by soluble sodium and acid-soluble. Removing ash can improve its gasification reactivity effect. NaCl has better effects than NaOH below 1100℃. Otherwise, NaOH is better.Secondly, the article hoose high sodium coal and two sorts of bituminous coal,which are mixed in accord with 5%,10%,15%and20%.It explores the combustion characteristics of high-sodium coal and blended coal by SDT-Q600 TGA. There are the following conclusions, that with the heating rate rising, high-sodium coal ignition temperature drops and the peak temperature range development delays; the mixing of coal combustion added with high sodium increase. the proportion of high-sodium coal blends to 15%, which makes the trend slowed.Finally, with the heating rate concerned, obtaining kinetics parameters of high sodium CO₂ coal gasification and coal combustion by using a semi-empirical model. The main conclusions include, increasing activation causes decrease of high temperature gasification of coal char gasification sodium with CO₂, but there is an upper limit of a gasification temperature-1150 ℃, if the gasification temperature continues to increase with higher limit temperature, activation energy will increase; plusing various forms of alkali metal sodium can reduce the activation energy of high sodium with CO₂ coal gasification reaction, activation energy of ash removal coal with NaOH is less than the coal with NaCl, also effect of NaOH is better than NaCl from the description of the dynamics of the catalytic; for mixed coal combustion, as the high sodium coal are added,mixed coal activation energy and pre-exponential factor are significantly decreased; but the proportion of high-sodium coal combustion is raise to 15%, the blended coalactivation energy and pre-exponential factor decrease slowly.