Innovative downdraft gasifier design utilizing exhaust gas as gasification agent for sustainable syngas production

Abstract

This study introduces an innovative downdraft gasifier design that harnesses exhaust gas as the gasification agent, showcasing successful operation and extensive experimental investigations using various biomass feedstocks, notably wood pellets of different sizes (<20 mm to 20–50 mm). The gasification system exhibited the ability to produce clean syngas suitable for both heating and electricity generation. Experimental assessments encompassed a temperature range of (620 to 1250 ℃) and an equivalence ratio range of 0.2 to 0.5. The resulting syngas composition featured key constituents such as H2, CO, CO2, and CH4, consistent with conventional gasification processes. The incorporation of exhaust gas as the gasification agent represents a pioneering advancement. This innovative approach not only minimizes energy input but also reduces greenhouse gas emissions, rendering the system more environmentally sustainable. The flow rate of the primary gasification agent was measured at 440 m3/h, and the producer gas’s exit temperature (300–650 ℃) was analyzed based on the moisture content of the biomass feedstock. The temperature within the reaction zone varied depending on the equivalence ratio (ER) for exhaust gas (700–974 ℃) and for air (ranging from 620–850 ℃). Additionally, the temperature was influenced by the moisture content, with ranges of (830–1050 ℃) for exhaust gas and 850–1050 ℃ for air. The syngas produced consisted mainly of carbon monoxide (14.4%–19.2%), hydrogen (16%–20%), carbon dioxide (7.1%–11.2%), and a small amount of methane (2%–3%). This innovative downdraft gasifier design holds substantial promise as a renewable energy system, particularly due to its utilization of low-cost materials and reduced environmental footprint. Such advancements pave the way for the widespread adoption of downdraft gasifiers, making them an attractive technology for thermal and power applications, especially in developing nations.