Circulation Multistage Fuidized Bed Combustor Design Concept
Publication Date: 2012-Jul-17
The IP.com Prior Art Database
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CTWCIILATTNG ~I].TT~TACE FT.ITTDTVVD BED COMBUSTOR DESIGN CONCEPT
Lowell D. Fra]ey Keh-Hsien Hsiao
/a~u~aLi <:as) Sadhukhan lung-Y1 L1n
In a previous s[udy for DOE, M. W. Kellogg performed a design analysis for the Kellogg CFBC. The analysis conclusively showed that the Kellogg CFBC met or exceeded perfor- mance criteria for advanced atmospheric FBC's. The Kellogg
CFBC is described in prior publications (i-6).
This paper presents the results of a further study made for DOE to reduce capital and operating costs of the Kellogg CFBC, configured into an industriai" boiler system of 150,000 pounds per hour steaming capacity. The results show the Kellogg CFBC to be a very economical concept.
When compared to the lowest cost bubbling-bed system of the same capacity, the Kellogg CFBC is 24% less costly. The basic equip-
ment cost has a greater difference~ $40.6/1000 ib steamfor the CFBC
and $59.3/1000 ib steam for the bubbl~ng-bed, i.e., 32% less costly.
The cost of steam from the opti- mized Kellogg CFBC is 18.8% less
] /M. W. Kellogg Company, Technology |Industrial Park Ten, Houston, TX 77084
_ /M. W. Kellogg Company ~ . /M. W. Kellogg Company ~ ~ /M. W. Kellogg Company i D /M. W. Kello Com an ~ve[
than from a bubbling-bed system. During the earlier DOE study and subsequent scale-up studies, areas of over-conservatism in Kellogg's design were identified. Of particular concern was the basic kinetic model wherein only sulfur dioxide reactions with lime had been considered and which had not adequately accounted for coal devolatilization. The first effort was to remedy these deficiencies and take into account reactions occurring under reducing conditions (primary air less than stoichi- ometric), mainly H2S-CaO
reactions and nitrogen compounds degrading to nitrogen. The computerized kinetic model has proven to be a powerful tool. It presents a better understanding of the complex reactions that occur in the CFBC's simple geometry and allows designers to develop a feel for the interactions of parameters of importance. The targets of reduced combustor height, diameter and pressure drop were readily achieved. Additionally, the nuances of ~igher temperatures and very fine particles were easily developed. A one T~ pilot plant has been constructed at the MWK Technical Development Center to verify the kinetic model.
)pment Center, 16200 Park Row,
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~h~!~a~l~'~'scale~up studies made by Kellogg identified several system areas whic~ needed intensive review since thel~ contributions to capital cost appeared excessive: structures, piping, and instrumen- tation/control. It appeared that some additional c~st savings could be achieved in th~ coal/llmestone feed system, cyclones, and boiler by more innovative design. Accord- ingly, a full design review by
Kellogg's commercial engineering staff was made.
The following sections describe MWK CFBC concepts, the kinetic model, a description of the pilot plant, plant design f...