Rapid pyrolysis of coals in a down-flow reactor(I). Rapid pyrolysis of Taiheiyo coal.

A coal pyrolysis and combustion combined system, which aims at recovering gaseous and tarry liquid products by pyrolysis of coals as well as heat (electric power) by combustion of all chars produced, is considered to become a feasible first step to promote effective use of coal resources.From the standpoint, a rapid pyrolysis of coals is being studied in a down-flow reactor which is heated by a high temperature sand; this is because high caloric gaseous and tarry liquid products can be effectively recovered from coals.In the present study. Taiheiyo coal was rapidly pyrolysed to clear relation between pyrolysis conditions (pyrolysis temperature, length of heating section and temperature of heat carrier), product distribution (yield of produced gas, tar and chars) and the properties of the products.1. Yields of chars decreased while those of gases increased, with increasing of pyrolysis temperature and length of heating section. A maximum tar yield was shifted to higher pyrolysis temperature in a shorter length of heating section, and was estimated to 30% in the pyrolysis temperature of 600-650°C in a longer length of heating section, because tars produced were secondarily pyrolysed.2. Rapid pyrolysis of a sample coal was finished in a second order. Maximum pyrolysis rates depended on pyrolysis temperature.3. Rapid purolysis of a sample coal was not effected with temperature of sand as a heat carrier.4. Combustibility of chars produced was considered not so different from a sample coal because they had higher caloric values and was, not coagulated in a pyrolysis step.5. Gaseous products were composed of H2, CH4, CO. CO2, and C2-C4 hydrocarbon gases. They had high caloric values of 5, 000-8, 500 kcal/Nm3.6. Elemental and NMR analyses of tars produced showed that the properties changed from paraffinic to aromatic with progress of the secondary pyrolysis followed by increase of pyrolysis temperature. They had caloric values of 6, 000-7, 500kcal/kg.