June 11, 2007 - Stacked Air System With One Wall Primary Improves Recovery Boiler Operation.

A pulp and paper company in Thailand recently installed a new “stacked air” combustion air system on their Tampella recovery boiler.  The boiler processes soda liquor and suffered from extremely short runtimes requiring stopping the boiler for cleaning on a weekly basis.  The mill desired to increase the runtime on the boiler and increase the liquor loading if possible.

Soda liquor has a higher melting temperature than sulfur based liquor which causes the primary ports and smelt spouts to black over quickly.  This required extra operator effort and the smelt spouts especially required constant attention.  Stacked air systems have proven to increase lower furnace temperatures and it was expected this would help raise the temperature of the smelt. To further alleviate the problems three walls of primary air ports were blocked leaving just the spout wall ports open.

This paper will review the before and after operation of the boiler; explain the changes made to the combustion air system; briefly explore the results of the CFD model; examine the benefits and results of the stacked air system with one wall primary; and present the experiences of the boiler operators before and after the modification.  It will be shown that a modern combustion air system can alleviate problems associated with soda recovery boilers while increasing runtime and throughput.

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Dec 10, 2006 - Stacked Air System Improves Recovery Boiler Operation

CENIBRA Celulose Nipo-Brasileira, Brazil installed a Stacked-Air combustion air system on their #2 recovery boiler in May 2004.  The new combustion air system improved run time, mechanical carryover throughput, emissions, chemical reduction efficiency, auxiliary fuel usage, and char bed control.  Instrumental to the success of the system was the use of computational fluid dynamic (CFD) modeling of the recovery boiler.  Five potential solutions were examined and compared to the base case condition.  Extensive data was collected of the before and after conditions including operational data.  The historical operation of the boiler is described and the benefits of the new combustion air system are reviewed.  The before and after conditions predicted by the CFD modeling are compared.  The boiler performance data is compared to the modeling predictions to illustrate the accuracy of “best practice” CFD modeling.  The boiler performance data is also used to document the improved operation of the boiler.  This case study illustrates the benefits of innovative combustion air systems and CFD modeling for improving the operation of recovery boilers. The advent of computational fluid dynamic (CFD) boiler modeling, and the introduction of new combustion air system designs, provided the mill with the tools they needed to finally solve the operational problems with the boiler.

For a full copy of this report e-mail InfoRequest@AnthonyRoss.com

Interstate Paper, Riceboro, Georgia, installed a Stacked-Air„· combustion air system on their recovery boiler in May 2003.  The new combustion air system improved run time, through put, emissions, reduction efficiency, auxiliary fuel usage, and char bed control.  Instrumental to the success of the system was the use of computational fluid dynamic (CFD) modeling of the recovery boiler.  Five potential solutions were examined and compared to the base case condition.  Extensive data was collected of the before and after conditions including interior gas temperatures, physical carryover and operational data.  The historical operation of the boiler is described and the benefits of the new combustion air system are reviewed.  The before and after conditions predicted by the CFD modeling are compared.  The boiler performance data is compared to the modeling predictions to illustrate the accuracy of ˇ§best practiceˇ¨ CFD modeling.  The boiler performance data is also used to document the improved operation of the boiler.  This case study illustrates the benefits of innovative combustion air systems and CFD modeling for improving the operation of recovery boilers.

For a full copy of this report e-mail InfoRequest@AnthonyRoss.com