This week a new paper has been published in the IFRF Combustion Journal (http://www.journal.ifrf.net/) entitled:

 Increase of the effective energy from the radiant tube equipped with regenerative system in comparison with a conventional recuperative system

 by:

 N. Rafidi, W. Blasiak, M. Jewartowski, D. Szewczyk

This article discusses experiments undertaken with a radiant tube fired with both regenerative and recuperative burner systems. The authors use their detailed measurements of tube temperature and heat flux to discuss the advantages of regenerative burner firing. This paper provides a good comparison of these two burners systems and is recommended reading for operations engineers investigating switching from conventional to regenerative burner systems.

Summary

The paper presents the experimental results of High Temperature Air Combustion (HiTAC) investigations with the use of a radiant tube, in order to compare the Regenerative System (RS) with a conventional recuperative system.

For this work a semi-industrial HiTAC test furnace was equipped with the W-shape Radiant Tube. The working length of this tube was around 7,0 m and the diameter was 0,195 m. The radiant tube was operated in sequence with a conventional recuperative system and a Regenerative System. The recuperative burner was mounted in the upper end of the tube.

The RS consisted of two burners, equipped with honeycomb ceramic regenerators, mounted to both ends of the radiant tube. The temperature profile of the tube wall was monitored by 74 thermocouples located along the tube. Additional temperatures, flow rates and pressures were measured to assess and compare the energy balance of both systems. Pollutant emissions, including NOx and CO, as well as the exhaust gas composition were measured.

The tests were carried out over a wide range of parameters: firing power from 75 kW to 155 kW, furnace temperature from 670C to 950C and an oxygen molar fraction in the exhaust gases set at 3%.  LPG was used as a fuel in all tests.

Test results show that the temperature profiles along the tube were more uniform when the regenerative system was used.  The cross-sectional temperature distribution for the tube was also more uniform. Because of the relatively flat temperature distribution along the tube, more energy from the radiant tube can be emitted using RS in comparison with the conventional recuperative burner, for the same maximum temperatures of the tube. In certain conditions, the increase of energy release can be up to 100%.

Energy balance calculations show that the efficiency of the Regenerative System can be up to 25% higher than that of the recuperative system, mainly due to very low temperature of flue gases for RS operation. Although, the preheated air temperature used for combustion was much higher in the case of the regenerative system (in some tests as high as 960C), the NOx emission was found to be almost the same in both cases.

Corresponding Author
Wlodzimierz Blasiak
Royal Institute of Technology
Energy and Furnace Technology Division
Brinellvägen 23
100 44 Stockholm
SWEDEN

Tel. No.: 46 8 790 84 05
Fax No.: 46 8 207 68 1

Email: Blaziak@mse.kth.se

Key words: HIGH TEMPERATURE AIR COMBUSTION, RADIANT TUBE, REGENERATIVE BURNERS

FULL PAPER

The full paper may be downloaded from the server, in the “New Papers” section (http://www.journal.ifrf.net/articles.html), by clicking on the Acrobat PDF icon alongside the title.

Publication in the Journal

The Editor-in-Chief (See associated article in this edition of the MNM) would like to remind all potential authors that publication in the Journal is open to all. If you have interesting results to publish in the field of, or related to, industrial combustion, we invite you to prepare a paper according to the guidelines given in the Author’s Guide on the website

http://www.journal.ifrf.net/

Papers may be regular “articles” (typically up to 20 pages) or Communications (typically up to 4/5 pages). Review papers can of course be longer. Remember that figures and graphics in general can be in full colour. This advantage should be encouraged.

All manuscripts and associated files, proposed for publication should be sent by the Corresponding Author in a compressed/zip file, as an email attachment to journal@ifrf.net. This file should include a statement that the proposal’s content is unpublished material that has not being submitted for publication elsewhere. When an article by the author(s) is cited in the proposed article as “in press”, a copy of this article should accompany the proposed article and should be included in the compressed file.

The Editor-in-Chief looks forward to receiving your proposals.