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Combustion of pure carbon in the presence of H 2 O and CO 2 using single and double film models
Author(s) -
Chen Wei,
Annamlai Kalyan,
Sundar Rohit
Publication year - 2018
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23177
Subject(s) - char , design for manufacturability , combustion , endothermic process , chemistry , phase (matter) , analytical chemistry (journal) , materials science , chemical engineering , thermodynamics , organic chemistry , physics , adsorption , mechanical engineering , engineering
In integrated gasification combined cycles systems, it is of interest to estimate the burn or gasification rate ( m ˙ ), particle surface/wall temperature (T w ), and flame temperature (T f ), and also control of the T w and T f with free stream CO 2 and the H 2 O level, which promote endothermic reactions. In the past, char combustion in the air was modelled using either a conventional single film model (SFM), or a conventional double film model (DFM). In this study, modified SFM and DFM models, including both heterogeneous reactions of CO 2 and H 2 O with C, and gas phase oxidation of both CO and H 2 , were developed. The SFM and DFM were switched to SFM‐DR (single film model with double reactions) and DFM‐DR (double film model with double reactions). The SFM‐DR assumes that the gas phase is frozen, with the final products being CO and H 2 , and the transfer number modified to B =Y O 2 , infv O 2 , I+Y C O 2 , infv C O 2 , I I I+Y H 2 O , infv H 2 O , I V; DFM‐DR includes gas phase oxidation of both CO and H 2 with O 2 , with the final products being CO 2 and H 2 O and the same modified transfer number B under infinitely fast chemistry. Finally, six different char combustion cases with or without H 2 O and CO 2 in the free stream were simulated to obtain the flame profile for modified SFM‐DR and DFM‐DR. It was found that reasonable flame profiles of char combustion were obtained for both SFD‐DR and DFM‐DR. Moreover, the O 2 ‐rich combustion could promote the endothermic Boudouard and steam‐carbon reactions. Finally, the burning rate (kg/m 2 · s) decreased with the increase of particle diameter for both SFM‐DR and DFM‐DR.