Experimental investigation on multi-stage downdraft gasification: Influence of air ratio and equivalent ratio to the gasifier performance

Abstract

Abstract. Multi-stage gasification process adding multiple air injection (at pyrolysis and oxidation) to reduce tar content and improve the efficiency. all components of the fuel can decompose perfectly into pyrolysis products and the total pyrolysis product also increases. The mean temperatures in the pyrolysis zone are respectively between 569 o C and 633 o C for the 0% and 90% Air Ratios. Temperature increases in the pyrolysis zone change the nature of the endothermal into exothermal and providing the heat energy for the drying, oxidation and reduction zones. While the temperature of the partial oxidation zone reaches 858 o C. For a total air flow of 10.5 Nm 3 /h with a 90% air ratio, the gasifier can produce a low tar content of 32.27 mg/Nm 3 when compared to 0% air ratio of 106.5 mg/Nm 3 . This result shown that multi-stage gasifier can reduce tar content by 30%.

Improved Municipal Solid Waste Gasification Efficiency Using a Modified Downdraft Gasifier with Variations of Air Input and Preheated Air Temperature

“…Although MSW is feasible to be used as fuel, because of the above limitations, it was necessary to make efforts to improve the performance of the gasification process to increase the syngas heating value and reduce the tar content. Several modifications have been done to improve the performance of gasification, including modifying the supporting system of the gasification process, namely, feeding, ash discharge, the grate, and the air inlet (single-stage and multistage air inlet), − and modifying the gasification model using cyclone gasification technology. − Another research study to enhance the performance of gasification was performed by preheating the air before the gasifier. − The air preheating treatment proved to be able to maximize the production of H 2 and CO, thereby increasing the syngas heating value and cold gas efficiency. However, preheated air was more effective at a low equivalent ratio (ER) .…”

“…Tar underwent cracking in the pyrolysis zone from primary tar to the secondary tar and reduced up to 45 mg/Nm 3 with an air input ratio of 100 and 120 L/min . Reduction of the tar content was varied from 30% to 50%. ,, Compared with the single-stage, the multistage gasification increased the H 2 production by 20% due to the temperature increase in the oxidation zone of up to 954 °C. Therefore, the temperature in the reduction zone also increased, thereby increasing the water–gas shift reaction rate. , Air input in the pyrolysis zone also increased the biomass consumption rate, which affected the superficial velocity and specific gasification rate .…”

Micro-Grid Oil Palm Plantation Waste Gasification Power Plant in Indonesia: Techno-Economic and Socio-Environmental Analysis

“…Multi-stage gasification power plant experiments have been carried out previously at the pilot scale with a capacity of 10 kW [18,20,31]. To estimate the economic value of a power plant on a micro-grid scale, in the analysis, the capacity was upscaled to 100 kW.…”

“…Gasification experiments were carried out using a multi-stage downdraft gasifier. The used equivalent ratio (ER) was the optimum ratio from previous studies [20,31] which was 0.4 while the air ratio (AR) for the pyrolysis zone, partial oxidation, and reduction were selected at the optimum ratio of 10%, 80%, and 10%. The AR percentage shows the amount of air entering for each zone, meaning that from the total air based on ER 0.4 divided into three locations, 10% into the pyrolysis zone, 80% into partial oxidation, and 10% into the reduction zone.…”

The Experimental Study of The Effect of Air Preheating in MSW Pellet Multi-Stage Downdraft Gasifier

“…MSW pellet composition comprises 60% organic matter and 40% inorganic [7]. Then, in this study, downdraft type reactors with multilevel air inputs in pyrolysis, oxidation and reduction zones [8] [9], and [10] were modified by adding external heaters to the inlet air. This external heater comes from an open coil heater that is installed in the air input pipe.…”