Green coal development for application in fixed-bed catalytic gasification

Abstract

A novel 'green coal' product formulation has recently been developed and the utilization concept tested at the North-West University coal research laboratories. Hydrothermal liquefaction was used to produce bio-oil and biomass char from sweet sorghum bagasse at operating temperatures ranging between 280 and 300°C, and the resultant char was mixed in various ratios (0, 0.25, 0.50, 0.75, and 1) with fine medium-rank C bituminous discard coal (<212 m) and CaCO 3 (1-5 wt%). The mixtures were pressed into 12 × 12 mm pellets using an LRX press at a pressure of 4 bar and gasified using CO 2 at atmospheric pressure and temperatures ranging between 800 and 1000°C. Kinetic parameters obtained from the experimental data showed that the reaction rate of the biochar was an order of magnitude higher than that of raw coal, with the blend containing 3 wt% CaCO 3 having the fastest reaction rate. In order to study the effect of temperature and catalyst on the retention of elemental sulphur during combustion of the various pellets, a combustion set-up consisting of a furnace, glass bayonet-type reactor, Liebig cooler, liquid traps, and an SO 2 gas analyser was used, with experiments conducted at temperatures between 500 and 800°C. As expected, sulphur retention was low for the raw coal and biochar blends, but increased significantly to between 56 and 86%, decreasing with increasing temperature, in the runs with added metal catalyst/sorbent. A simulation using FactSage TM predicted that >50% of the pyritic sulphur entering the fixed-bed gasifier would be removed from the gaseous phase as insoluble CaSO 4 when operated in a catalytic gasification mode at a temperature of 800°C, which is in good agreement with the experimental findings.Coal briquette, catalytic gasification, reactivity, sulphur retention.

Mechanical and Thermal Properties of Extrudates Produced from Discarded Coal Fines and Recycled Plastics as Binders

“…From a financial incentive, the use of coal fines would positively affect the environment and provide an additional source of coal available for utilization . To extend the life of the remaining coalfields, the utilization of discarded coal fines is beneficial and aligned with government policy …”

“…8 To extend the life of the remaining coalfields, the utilization of discarded coal fines is beneficial and aligned with government policy. 9 To be used in industrial processes, coal fines need to be agglomerated to improve the handling of the material. 5 These agglomerates need to adhere to mechanical strength standards 10 and must have water resistance properties.…”