High Fidelity Analysis of Entrained Flow Gasification (EFG) Supported by Experimental Studies

Student thesis: Master's Thesis

Abstract

Although there had been much effort in the modeling of entrained flow gasification in the recent past, very few experimental studies which can provide rigorous constraint to these models exist. To our knowledge, there exists no centerline species composition and temperature measurements for the entrained flow gasification of Kentucky coal. Without these axial experimental data, we will not be able to validate our models for the gasification of these fuels better. Hence, the investigation of the sensitivity of the developed model to various parameters in order to optimize the performance of the gasifier will be difficult. This study investigates the effect of gasification parameters like equivalence ratio, pressure, temperature, diameter, and height on the entrained flow gasification of Kentucky coal and wood waste. The objective of this study is to develop gasification models, with high predictability of experimental data, which can be employed in sensitivity studies. The development of these high fidelity models started with material characterization of the feedstocks (Kentucky RTC bituminous coal and waste wood) with DSC/TGA Q600, FLASH 2000 CHNOS and Parr 6100 bomb calorimeter in order to determine the suitability of the fuel and to obtain crucial data for modeling of the gasification process. Thereafter, the entrained flow gasification was achieved with the drop tube experimental facility at the Waste-2-Energy Lab. at Masdar Institute in order to obtain exit and centerline measurements which will give rigorous constraints in the validation of developed models. Furthermore, an ASPEN Plus kinetic model was developed with an RPlug reactor for the char gasification. This model allows for centerline parameter evaluation and helps to determine the effect of diameter and height of a gasifier on its gasification metrics. Lastly, a numerical model based on the Lagrangian-Eulerian scheme was used to obtain a closer prediction as compared to the ASPEN Plus model and to study the effect of parameters such as equivalence ratio, fuel type, pressure and temperature on gasification. The developed models are reasonably comparable to the experimental data obtained in this study. The Kentucky RTC coal and waste wood were observed to be very good candidates for gasification because they contain little quantity of ash and moisture altogether (less than 10%). The heating value of the Kentucky RTC coal (30.42MJ/kg) was almost twice that of the waste wood (18.7MJ/kg) due to the presence of higher fixed carbon content in the coal. However, the wood contained high oxygen (43.62%) and volatile (68.89%) content which implies that the volatile has a high oxygen content as the ash, fixed carbon and moisture has small oxygen content altogether.
Date of AwardMay 2014
Original languageAmerican English
SupervisorIsam Janajreh (Supervisor)

Keywords

  • Gasification; Coal; Biomass; Aspen; Devolatilization.

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