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This is the published version of a paper presented at 2015 AIChE Annual Meeting, November 8-13,
2015, Salt Lake City, UT, USA.
Citation for the original published paper:
Mirmoshtaghi, G., Skvaril, J., Li, H., Thorin, E., Dahlquist, E. (2015)
INVESTIGATION OF EFFECTIVE PARAMETERS ON BIOMASS GASIFICATION IN
CIRCULATING FLUIDIZED BED GASIFIERS.
In:
N.B. When citing this work, cite the original published paper.
Permanent link to this version:
INVESTIGATION OF EFFECTIVE PARAMETERS ON BIOMASS GASIFICATION
IN CIRCULATING FLUIDIZED BED GASIFIERS
G. Mirmoshtaghi. J. Skvaril. H. Li. E. Thorin. E. Dahlquist
School of Business, Society & Engineering. Mälardalen University. Box 883. SE-721 23 Västerås. Sweden
Abstract
Gasification of biomass is one of the technologies to convert solid fuel to gas for heat and power production. Gasification mechanism and efficiency has been studied for decades. However due to the complexity of the system and its sensitivity to operating parameters, the relations and impacts of different parameters on the gas quality and gasifiers performance are still not clear.
In this paper data that are collected from different Circulating fluidized bed gasifiers have been analyzed to detect the most influential operating parameters. The gas composition, carbon conversion and heating value of the gas are considered as the evaluation indexes to measure the quality of the product gas and gasifiers performance.
The multivariate analysis statistical tool has been used in this study. Principal component analysis (PCA) shows the grouping between different gasifiers and the positive/negative correlation between operating parameters and concentration of different components in the product gas. Also the influencing parameters on carbon conversion and heating value of the gas have been investigated.
The results show a strong negative correlation between CH4 and CO with equivalence ratio (ER). This means that
increasing ER value would decrease CH4 and CO concentration. This happens since the reactions move more towards
combustion. On the other hand H2 shows a strong positive correlation with temperature, pressure and steam to biomass
ratio (S/B). This can be related to cracking of larger hydrocarbons in higher temperature and larger S/B. However due to the exothermic characteristic of water gas shift reaction, higher temperature would result in lower CO2 amount
which proves the negative correlation between H2 and CO2 in this analysis.
Keywords: biomass, gasification, PCA, correlation, CFB gasifier 1. Introduction
Using biomass as a renewable resource of energy for fuel, heat and power production has been considered for many years. One of the technologies to convert the solid fuel energy to usable energy is gasification. [1]. In gasification there are different steps and reactions that are interrelated so due to the complexity of the system there are still unknown relations between the gas composition and operating parameters. Therefore different researchers such as [2] [3] [4] [5] [6] considered different ranges of input data and tried to analyze the impact of them on product gas composition. However in these studies, specific component or operating condition have been focused and studied. In some cases air gasification of a specific biomass in different operating condition has been studied [3] [5] [6] while in the other case different biomass species have been studied in one specific gasifier [2] [4]
In order to find the interrelation between different operating parameters and their impact on the gas quality, statistical approach is more effective. Doing multivariate analysis and using Principal component analysis (PCA) gives the opportunity to analyze the interrelated parameters and the degree of their influence on the output. There are different statistical studies addressing pyrolysis/gasification of biomass [7] [8], catalytic beds for gasification [9], soot characterization [10] and different biomass type [11]. However in this study the focus is on the CFB gasifiers with silica sand bed while all the important operating parameters have been considered.
2. Concept and Methodology
In this study PCA has been applied to a set of data collected for seven circulating fluidized bed gasifiers. The operating parameters have been considered are temperature, pressure, steam/biomass ratio, ER value, size of the reactor, residence time, biomass ultimate and proximate analysis. While the concentration of CH4, CO, CO2 and H2 together
with carbon conversion and heating value have been studied as output results
The scores and correlation loading plots show characteristic parameters and differences between gasifiers (groupings) and correlations between different gas compositions and the operating parameters respectively Also it illustrates the
most influencing parameters on the concentration of different components, carbon conversion and heating value of the product gas.
3. Acknowledgements
The authors express their gratitude to the Swedish energy agency for major financing of this project. 4. References
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