Optimum Conditions for Effective Decomposition of Toluene as VOC Gas by Pilot-Scale Regenerative Thermal Oxidizer

Authors: S. Iijima, K. Nakayama, D. Kuchar, M. Kubota, H. Matsuda

Abstract:

Regenerative Thermal Oxidizer (RTO) is one of the best solutions for removal of Volatile Organic Compounds (VOC) from industrial processes. In the RTO, VOC in a raw gas are usually decomposed at 950-1300 K and the combustion heat of VOC is recovered by regenerative heat exchangers charged with ceramic honeycombs. The optimization of the treatment of VOC leads to the reduction of fuel addition to VOC decomposition, the minimization of CO2 emission and operating cost as well. In the present work, the thermal efficiency of the RTO was investigated experimentally in a pilot-scale RTO unit using toluene as a typical representative of VOC. As a result, it was recognized that the radiative heat transfer was dominant in the preheating process of a raw gas when the gas flow rate was relatively low. Further, it was found that a minimum heat exchanger volume to achieve self combustion of toluene without additional heating of the RTO by fuel combustion was dependent on both the flow rate of a raw gas and the concentration of toluene. The thermal efficiency calculated from fuel consumption and the decomposed toluene ratio, was found to have a maximum value of 0.95 at a raw gas mass flow rate of 1810 kg·h-1 and honeycombs height of 1.5m.

Keywords: Regenerative Heat Exchange, Self Combustion, Toluene, Volatile Organic Compounds.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1330087

References:

[1] Ministry of the Environment Government of Japan, PRTR information plaza Japan, http://www.env.go.jp/en/chemi/prtr/prtr.html.
[2] Ministry of the Environment Government of Japan, "Cabinet Decision on a Bill to Control the Emission of VOCs", http://www.env.go.jp/en/press/2004/0308a.html, 2004.
[3] Ministry of the Environment Government of Japan, "Contents of New Emission Regulation of Volatile Organic Compounds", http://www.env.go.jp/en/press/2005/0606a.html, 2005.
[4] Ministry of the Environment Government of Japan, "Summary of VOCs emission control system", http://www.env.go.jp/air/osen/voc/seido/001.pdf, (in Japanese).
[5] H. Hayashi, "PSA shiki VOC-VRU souti", Dai 8 kai Toukai-tiku bunnri gijyutu kouenkai, 2007, pp.1-5, (in Japanese).
[6] Y. Ikeda, "VOC makubunnri kaisyu souti no goshoukai", Dai 8 kai Toukai-tiku bunnri gijyutu kouenkai, 2007, pp.6-11, (in Japanese).
[7] T. Yamamoto, "Houden wo riyoushita VOC shori gijyutu", Seidenkigakkaishi, 1995, vol. 19, no.4 pp.301-305, (in Japanese).
[8] Y. Yoshimura, "Netsu kaisyu kouritu ni sugureta tikunetushiki dassyu souti
[RTO] shouenerugi gata seibutu dassyu souti
[baio-supa]", Kogio Toryou, 1998, vol. 150, pp.80-83, (in Japanese).
[9] The Japan Society of Industrial Machinery Manufactures, "VOC shori gijyutu semina text", 1995, (in Japanese).
[10] A. Tsutida, S. Yamazaki and M. Akiyama, "Dennetsu Kogaku Ensyu", Gakken, 1965, pp.204-260 (in Japanese).
[11] D. Kunii, "Netuteki Tani Sosa (jyo)", Maruzen, 1976, pp.210-246 (in Japanese)