Bulk density of chopped wheat straw - Influence of moisture content, fine fraction content and coefficient of compaction

Abstract

Quantity and quality of producer gas, received from 1 kilogram of a fine dispersed plant raw material, depends greatly from its bulk density. Bulk density influences aerodynamic processes that take place in a layer of this material. A design of equipment for compacting plant raw material has been presented. A poly-fractional mixture of chopped wheat straw is used as a raw material. The investigation is done by the method of multifactor experiment, where the moisture content in the raw material, fine fraction content in the poly-fractional mixture of chopped wheat straw and its coefficient of compaction are variable factors. Based on the received data, response surfaces were built. The experimental results let define the optimal ranges of each parameter to provide the rational bulk density value, that provides the highest producer gas calorific value – 11.1 MJ·m-3. The obtained measurement results are in high correlation with the calculations. It was found that at the fine fraction content 50 % in a poly-fractional mixture, the coefficient of compaction 1.4 and moisture content less than 20 % bulk density is 200-250 kg·m-3. For that bulk density value the porousity coefficient is 0.54-0.61 that provides the best conditions for heat and mass exchange processes in energy production from poly-fractional mixtures of chopped wheat straw. The results let understand that it is possible to manage the gasification process and receive high values of the gasifier specific thermal productivity while changing the raw material bulk density. Using the obtained results the new laboratory practice for students of engineering courses was prepared and successfully tested.