Performance - Evaluation of Lignite in a downdraft Gasifier
India is a developing country which lacks an adequate supply of electricity. For many of the interior regions of India, gasification is a good way to produce electricity with standalone gasifier. In many regions of India as well as in the world, a large reserve of lignite is available. Lignite could be a fuel for gasification system. This paper presents the result of the experimental investigations carried out using lignite to investigate the effect of fuel size variation on gas generation rate and performance parameter in terms of calorific value of producer gas and gasifier efficiency in downdraft gasifier. Based on the realization, while studying the effect of gas generation rate, the choice of particle size is playing an important role for flowability study and performance of gasifier. The present work investigates the effect of lignite size variation on temperature profile at different zones in gasifier. They were in the range of 16-19 mm, 19-22 mm, 22-25 mm particle sizes of lignite. For comparative studies, experiments were also carried out on uneven size wood and lignite. It was observed from three particle sizes of lignite that better calorific value (629 kcal/m 3 ) and efficiency of gasifier (46.092%)
Performance of a down-draft charcoal gasifier
The gas composition and temperature profiles for charcoal, gasified in the down-draft mode, have been obtained from theoretical considerations. The prediction is based on kinetics and the heat and mass transfer mechanisms in an air-blown gasifier at atmospheric pressure. The charcoal has been assumed to be pure carbon, i.e. free from volatile matter and ash. Parametric studies were made on solid and gas flow rates, char reactivity and particle size, both with dry air and with steam in the system. The rate parameters used were those for anthracite coke and were taken from published literature, with appropriate reactivity corrections. The results showed the O2 consumption took place very rapidly, in a distance of about 10-15 cm from the level at which air entered; the CO2 concentration dropped after increasing to a maximum; the CO and H2 concentrations continually increased from zero. The model predictions agreed reasonably with experimental results.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.