In this study, a pilot-scale regenerative thermal oxidizer (RTO) was used to test its performance for volatile organic compound (VOC) destruction and degree of thermal energy recovery. The purposes were to improve its performance and establish its operation conditions.
The RTO is electrically heated and contains two 0.5 m ¡Ñ 0.5 m ¡Ñ 2.0 m (L ¡Ñ W ¡Ñ H) beds both packed with gravel particles of around 1.16 cm in average diameter to a height of 1.48 m. The bed has a void fraction of 0.405.
Experiments include two phases: (1) tests to find the degree of energy conservation and the pressure drop for the air stream with no VOC in the influent air stream, and (2) tests to find the degree of VOC destruction with influent air streams containing one of the three VOCs: trichloroethylene, dichloromethane, and dibutyl ether. Intermediates in the course of VOC destruction were also detected in the second phase experiment.
Phase one experiment was conducted for the following conditions: superficial gas velocity (evaluated at ambient temperatures of 26-29oC) Ug = 10-20 m/min, bed shift time ts = 1.5 min, and maximum gravel temperature Tmax = 474-778oC. Results show that the RTO has a thermal recovery efficiency R of over 85% and Ug is the main affecting factor. R is inversely proportional to Ug. Gas pressure drop over the bed height is proportional to the average temperature of the bed gravels.
In the phase two experiments, Ug of 10-20 m/min, ts of 1.5 min, and Tmax of 475-487 and 758-778oC were used. Results show that over 90% of the influent VOCs were destructed when Tmax was set in the higher range. However, in the lower Tmax, over 80% destruction was obtained only for dibutyl ether and the VOC destruction was not closely related to Ug.
For Tmax = 475-487oC and Ug = 10-20 m/min, complete oxidation products of trichloroethylene and dichloromethane are HCl, CO2, and H2O, and the main intermediates are CO, COCl2, and C2Cl4 (detected only for trichloroethylene). For dibutyl ether, complete oxidation products are CO2, and H2O, and the main intermediates are CO, alkenes, alcohol, alkenes, and acetic acid. For Tmax = 758-778oC and Ug = 10-14.5 m/min, complete oxidation products of trichloroethylene and dichloromethane are HCl, CO2, and H2O, and the main intermediates are CO and COCl2. No acetic acid was detected for dibutyl ether in the higher temperature range.
An operation cost of US$ 3.33/(1,000 m3 waste gas) was estimated with the RTO operated in the higher temperatures and a flowrate of 2.5 m3/min (Ug = 10 m/min).
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0711102-212542 |
| Date | 11 July 2002 |
| Creators | Hei, Cheng-Ming |
| Contributors | none, Ming-Shean Chou, Kang-Shin Chen |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0711102-212542 |
| Rights | off_campus_withheld, Copyright information available at source archive |
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