Specifications and design of a pressurized laminar-flow isothermal reactor for studies of coal reactivity

One facet of the larger project entitled The Characteristics of American Coals in Relation to Their Conversion to Clean Energy Fuels is intended to develop and test a series of reactor vessels capable of providing quantitative data on coal performance in reactions important in the gasification of coal, and to generate quantitative data on the pyrolysis behavior and reactivities of representative coal lithotypes and chars derived therefrom. A most important task element of this facet is the design, construction and testing of a pressurized isothermal reactor capable of operating at temperatures up to 1300/sup 0/C and at pressures up to 100 atmospheres. Required is an experimental system that will best permit rapid heating, isothermal reaction, rapid quenching of the sample reaction, variation of reaction time, study of pyrolysis or reaction with ambient gases, pressurization, and unambiguous reaction history. Attainment of these characteristics is the objective of the facet element described herein. The system is designed to feed coal dust at a pre-set rate into a controlled high temperature and pressure reactor, in the presence of hydrogen or other reactive gas, and then separate the solid effluent from the gas

Characteristics of chars produced by pyrolysis following rapid heating of pulverized coal. [104 references]

A 5.08-cm id pyrolysis furnace has been used to study pyrolysis following rapid heating of size graded pulverized coal particles as a function of isothermal pyrolysis time (0.018 to 1.025 second), particle size (50 to 181 ..mu..m), and parent coal (three lignites). The following experimental conditions were kept constant: Coal feed rate approximately equal to 0.5 g/min; volumetric flow rate of nitrogen temperature = 808/sup 0/C, and pressure = atmospheric. Under these conditions the heating rate of the coal particles in the pyrolysis furnace was of the order of 8 x 10/sup 3/ /sup 0/C/second. The experimental results show: (i) a monotonic change in the physical properties of chars with increasing pyrolysis time; (ii) some dependence of weight loss (i.e. VM yield) on particle size; (iii) that the three lignites undergo pyrolysis to a comparable extent, presumably because of their similar initial chemical composition; (iv) an appreciable influence of temperature and heating rate on weight loss in the Parr VM crucible; and (v) a significant influence of the mode of pyrolysis (i.e. entrained vs fluid bed) on the nature of the char produced. The results from a theoretical treatment of the problem of gas-solid interactions suggest that, in the pyrolysis furnace, all coal particles smaller than 200 ..mu..m in diameter are heated from their initial room temperature to the predetermined gas temperature of 808/sup 0/C so fast that no appreciable gradient is established between their surface and their center