Co-combustion of high density polyethylene and lignite mixtures

Production and consumption of plastic materials, which are petroleum products, have been increasing each year since their discovery. This increase leads to the rise of the rate of plastic waste in industrial and domestic waste. Recycling methods are applied on the recycling of plastic wastes due to the reduction of waste storage areas and damages to human health and the environment. The world's energy demand is constantly increasing due to population growth and industrial development. Fossil fuels are still the main energy sources in electricity generation. Approximately 41% of the electricity production in the world is represented by the burning of coal. As an alternative fuel in the production of steam or electricity, the incineration of biomass with coal is important for the reduction of landfills and protection of fossil resources. It is equally important to use plastics in the combustion process together with coal after environmental and economic use. Since plastic materials are lightweight, it is important to apply the pelletizing (concentration) process in order to facilitate the storage and transportation process. In this study, the co-burning of Afşin Elbistan Lignite (AEL) which is selected as lignite with raw high density polyethylene (HDPE) has been examined. The effect of mixing ratio and temperature on combustion behavior of pellets, prepared with certain ratios of these materials, in fixed bed combustion system were investigated. It was determined that the ignition times of AEL-HDPE blends were shortened with the increase in HDPE ratio. In addition, it was determined that the volatile substance burning times increased with the increase in the HDPE ratio. It was determined that the ignition times of AEL-HDPE mixtures were shortened with the increase in HDPE ratio, while the combustion of volatile substances increased with the increase in HDPE ratio. It was found out that the carbon burning time of the mixtures decreased with the increase in the HDPE ratio. It is observed that there is no relationship between volatile substance burning time and volatile combustion rate, but there is a relation between carbon burning time and carbon burning rate. It was observed that the oven start temperature was effective on the duration of ignition, volatile matter burning and carbon burning time. It was concluded that the volatile matter combustion rate of each blend pellet increased with temperature and that the carbon combustion rate did not show a regular change with temperature.