Showing papers by "Ajay Kumar published in 2019"

Modeling low temperature plasma gasification of municipal solid waste

Abstract: Plasma gasification requires high energy input and temperature, hindering adoption for commercial applications. In this study, a model of low-temperature plasma gasification is investigated to convert municipal solid waste (MSW) into syngas. The model was employed at reactor temperatures of 1,500, 2,000, and 2,500 °C to assess effects on syngas composition and system performance with air as the plasma medium. At plasma temperatures of 1,500, 2,000, and 2,500 °C, the model generated syngas lower heating values of 5.41, 6.02, and 6.45 MJ/Nm3, respectively, with energy inputs of 2,358, 2,775, and 3,245 kW per kg/s of MSW, respectively, and plasma gasification efficiencies of 49.6, 49.2, and 48.9%, respectively. In comparison to conventional non-plasma air gasification of MSW, syngas generated from low-temperature plasma gasification contained higher concentrations of hydrogen and carbon monoxide, resulting in higher heating value of the syngas.

Physicochemical properties and morphology of biochars as affected by feedstock sources and pyrolysis temperatures

Abstract: Feedstock sources and pyrolysis temperatures affect the physicochemical and morphological properties of biochars. We evaluated biochars derived from switchgrass (SGB) and poultry litter (PLB) pyrolyzed at 350 °C (SGB350, PLB350) and 700 °C (SGB700, PLB700) to identify their potential ability in improving soil health. Except for SGB350, the pH of biochars was high (> 10.0) and can be used as an amendment in acid soils. PLB700 had higher mineral content and nutrient availability due to its higher ash content (tenfold higher) and electrical conductivity. Surface functional groups responsible for metal retention were evidenced in all biochars. Cation exchange capacity (CEC), specific surface area (SSA), and microporosity more than doubled by increasing pyrolysis temperature from 350 to 700 °C. The pH-buffering capacity measured through acid titration curve was better than that calculated with acid/alkali additions. Biochars pyrolyzed at 700 °C have much higher pH, CEC, SSA, and stronger buffering capacity, and thus are more promising to improve soil health and reduce contaminant bioavailability.