Study of Molding and Drying Characteristics of Compressed Municipal Sludge-Corn Stalk Fuel Pellets

Abstract

Sludge incineration is a sludge resource management and disposal method that can greatly decrease the volume of sludge, reduce the degree of harm and realize the recovery of sludge heat energy. Most of the research on sludge incineration focuses on the combustion process and gas emissions, but there are relatively few studies on the sludge fuel molding and drying process before sludge incineration. Besides, independent incineration of sludge has high energy consumption. This paper proposes a pre-incineration treatment method in which sludge and corn stover are mixed to make fuel pellets and then dried. Specifically, the influence of molding pressure, raw material ratio and raw material particle size on the physical properties of the fuel, and the related mechanism, were studied. The density of fuel particles is mainly affected by the forming pressure, and the impermeability is mainly determined by the proportion of sludge in the raw material. The order of the variables based on their effect of improving fuel physical properties was: molding pressure > raw material ratio > raw material particle size. Moreover, the influence of drying temperature (40 °C, 60 °C, 80 °C, 100 °C, 120 °C) has been explored. When the initial water content is similar, the drying rate increases with the increase in temperature. It provides a reference for the sludge fuel molding and drying process, and promotes the practical application of mixing sludge and corn stalks to make fuel.