DEFINITION OF WET WOOD PARTICLES IGNITION CONDITIONS AND CHARACTERISTICS TO INCREASE THE RESOURCE EFFICIENCY OF HEAT POWER ENGINEERING

Abstract

The relevance. Analysis of experts' forecasts shows that the growth in global electricity consumption until 2030 will be 2,4%. Today, the energy generated at thermal power plants is 2/3 of the total energy generated by all sources. For most thermal power plants, coal is the main fuel. The share of thermal power plants burning coal reaches 40%. Burning coal leads to intense emissions of nitrogen oxides and sulfur,the main consequences of which are deterioration in human health, smog and acid rain. One of the new solutions to the environmental problems of the energy industry is the combustion of biomass (sawmill and forestry waste). According to experts, the volume of timber reserves in Russia exceeds 82·109 m3 and accounts for 25% of the world reserves. Waste from its processing is more than 30·106m3 per year. Environmental requirements for heat and power facilities are constantly growing. This determines the interest in biomass use. The main aim of the research is todetermineexperimentally the dependences of ignition delay times during high-temperature heating of woody biomass of different moisture content using the example of four fairly accessible and widespread wood species (the most high-calorie and, therefore, promising) for heat power engineering. Object: dry and moisture-saturated wood of four types (cedar, larch, pine and aspen). Experimental studies were carried out for wood particles with relative humidity: 5, 30 and 45%. Methods: experimental determination of the ignition temporal characteristics of wood particles under conditions corresponding to the intensity of heating to the combustion chambers of steam and hot water boilers using a high-speed video camera Photron FASTCAM CA4; registration of medium temperature using chromel-alumel thermocouples. Results.The paper introduces the results of the experimental studies of ignition of dry and wet particles of four type of woody biomass in the environment of air heated to high temperatures in order to substantiate the resource efficiency of using woody biomass (as the base fuel of steam and hot water boilers). A significant effect of the wood type on the ignition conditions and characteristics of its single particles was established. A significant influence of humidity on the ignition delay times of particles of the studied types of biomass was established as well. Such times, corresponding to wood in its natural state, are 3–4 times higher in the entire (rather wide) range of change of temperatures significant for practice, the ignition delay times of dry wood particles. The regularities established in the conducted experiments illustrate the prospects of using woody biomass in heat power engineering as the main fuel or components of a charcoal mixture.

Keywords

• wet wood
• biomass
• ignition
• ignition delay time
• thermal fuel preparation
• experiment
• energy efficiency