Abstract:
The coupling of organic solid waste and coal-fired units to generate electricity is one of the effective ways to achieve harmless disposal of solid waste and reduction of coal consumption and carbon reduction. In this paper, three typical organic solid waste pyrolysis semi-cokes, namely, waste textile, wood chips and rubber, were produced using a fixed-bed reactor system, and the effects of raw material characteristics and pyrolysis temperature on semi-coke yield and calorific value were analyzed. A thermogravimetric analyzer was used to study the mixing characteristics and interaction mechanism between organic solid waste semi-coke and lignite at different mixing ratios. The results show that, in the pyrolysis process, organic solid wastes with low ash and high cellulose content were suitable for pyrolysis at higher temperatures, while petrochemical organic solid wastes with high ash content were suitable for pyrolysis at lower temperatures, and the optimal pyrolysis temperatures for waste textiles, wood chips and rubber were 450, 400, 300 ℃, respectively. There are 2 different interactions between low volatile solid waste semi-coke and high volatile coal species in the mixing and combustion process, the promotion mainly occurs in the ignition and volatile combustion stages, mainly due to the rich pore structure in the semi-coke which increases the combustion surface area and facilitates the transfer and diffusion of oxygen; secondly, the promotion also occurs in the combustion interval with small fluctuations in the combustion rate. The inhibitory effect mainly occurs in the stage of fixed carbon combustion and combustion exhaustion, mainly due to the large amount of oxygen consumed by the combustion of volatile components in the pre-combustion stage and the coverage of the combustion surface by the cracked tar of the heavy volatile components, which leads to the deterioration of heat and mass transfer conditions in the late stage of the combustion of the fuel, and this inhibitory effect will also be gradually weakened with the catalytic effect of the inorganic components in the fuel. The combined index of combustion characteristics and interactions of the blended fuels was quantified using total composition analysis, and the optimal blending ratios of 20%, 40% and 80% were obtained for waste textile, rubber and wood chip semi-coke, respectively.