Technical assessment of oxyfuel combustion in lime kiln: mass and energy balance perspective

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Journal Title

Journal ISSN

Volume Title

Kemian tekniikan korkeakoulu | Master's thesis

Authors

Date

2024-06-11

Department

Major/Subject

Chemical and Process Engineering

Mcode

CHEM3043

Degree programme

Master's Programme in Chemical, Biochemical and Materials Engineering

Language

en

Pages

59 + 1

Series

Abstract

Growing Incentives for emission reduction in process industry has prompted development of novel solutions. Oxyfuel combustion is one of the emerging technologies which enables a facile carbon dioxide capture by substituting air with pure oxygen in combustion process. The concept has been proven to bring various advantages in different processes, including power generation, glass manufacturing and metal industry. Moreover, several studies on integration of oxyfuel technology to cement plant as a major source of industrial emission has revealed its potentials for rotary lime kilns. However, the reported studies on lime kilns are rare. In this study, a review of existing literature on oxyfuel combustion shed light on a various perspective of the concept, such as combustion, heat transfer, oxygen supply, practical challenges, and limitations. Furthermore, it was investigated that how implementing oxyfuel combustion in rotary lime kilns impacts mass and energy balances. The oxyfuel models were established utilizing CHEMCAD process simulator. Six different flue gas recycle configurations for three different kiln fuels were considered. The case studies vary with respect to flue gas splitting location, and flue gas treatment elements through recycle path. The flue gas recycle ratio (FGR) was detected as a crucial factor. Hence, its effect on kiln balances was examined in the range of 0.30 to 0.70. Oxygen demand, CO2 production, and the quantity of condensed water were estimated for different fuels. Finally, the operating boundaries were determined based on flame temperature, feed-end temperature, solid bed temperature, and oxidizer O2 concentration. Two scenarios, based on direct recirculation of flue gas after feed-end, yielded undesirable operating conditions. In contrast, four other scenarios were found to be feasible at specific FGR ranges. Accordingly, wet recirculation of flue gas imposes operating conditions with lower FGR values. The findings also indicated the pattern of variation in critical process parameters are rather similar for the selected fuels, with a certain level of dissimilarity originating from fuel composition and heating value.

Description

Supervisor

Oinas, Pekka

Thesis advisor

Vähä-Savo, Niklas

Keywords

oxyfuel combustion, lime kiln, flue gas recycle, mass and energy balance

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Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202406164419

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[dipl] Kemian tekniikan korkeakoulu / CHEM