Regenerative afterburning

from Wikipedia, the free encyclopedia

The regenerative oxidation (RTO) or regenerative thermal oxidation ( English regenerative thermal oxidation RTO) is a process for thermal waste gas purification . It is preferably used to reduce hydrocarbon emissions. It is characteristic of the process that no steady state is reached. Regenerative afterburning was introduced in the United States in 1972 .

Basics

To reduce hydrocarbon emissions, the loaded exhaust gas is burned in a combustion chamber. A burner is required to heat the combustion chamber and to maintain the necessary operating temperature. If autothermal combustion is not possible, liquid or gaseous fuel or a combination of both must be added to the exhaust gas. A supply of combustion air is necessary if the exhaust gas contains too little molecular oxygen.

With regenerative post-combustion, the treated exhaust gas gives off its heat to a regenerator , which in turn heats the untreated exhaust gas, which reduces the energy required for combustion. Treated and untreated exhaust gas flows through the regenerator alternately. For this reason, clocking and appropriate interconnection is necessary and the presence of at least two regenerators is advisable. If a rinsing step is included, another regenerator is required. A larger number of regenerators is usually used for larger exhaust air volume flows.

The main element of a regenerator is a heat storage mass. As a rule, the heat storage masses are designed as honeycomb bodies. Honeycomb bodies have a lower pressure loss compared to bulk material . The oxidation of the pollutants already starts within the regenerator, but mostly occurs in the combustion chamber. In special cases, the chemical conversion takes place within the regenerator, so that there is no need for a combustion chamber.

An important parameter of regenerative post-combustion is the degree of burnout, which indicates how large the proportion of completely converted combustible substances is. It can essentially be changed by changing the parameters

to be influenced.

Another important parameter for evaluating processes is the degree of exhaust gas preheating ( ), which represents the ratio of the enthalpy flow transferred to the difference between the enthalpy flows of the treated and untreated exhaust gas:

According to the state of the art , exhaust gas preheating degrees of 95% are possible. The process is autothermal with exhaust gas loads of a few grams per cubic meter.

application

Systems for regenerative afterburning are used in a wide variety of industries and companies. These are among others:

Depending on the industry and provider, regenerative exhaust gas cleaning is also offered as "flameless regenerative thermal oxidation" (FRTO), "thermal regenerative exhaust gas cleaning" (TRA), "regenerative combustion system" (RVA) or "thermoreactor".

particularities

Regenerative afterburning is a further development of thermal afterburning . With it, since temperature peaks can be avoided, low nitrogen oxide emissions are achieved. If organosilicon compounds (e.g. siloxanes ) are to be expected in the exhaust gas, blockages and incrustations of the regenerator are to be expected.

Since in regenerative post-combustion the temperature of the treated exhaust gas is only slightly higher than that of the untreated gas, the water content of the treated exhaust gas can be visible as a condensate plume, depending on the weather.

literature

  • VDI 2442: 2014-02 exhaust gas cleaning; Processes and technology of thermal waste gas cleaning (Waste gas cleaning; Methods of thermal waste gas cleaning). Beuth Verlag, Berlin. ( Summary and table of contents online )

Individual evidence

  1. ↑ a b c d e f Otto Carlowitz, Olaf Neese: Starting points for the conceptual and operational optimization of thermal exhaust gas cleaning systems with regenerative exhaust air preheating. In: Hazardous substances - cleanliness. Air . 65, No. 7/8, 2005, ISSN  0949-8036 , pp. 320-327.
  2. ↑ Torsten Reindorf: Modeling and analysis of the operating behavior of thermal post-combustion systems with regenerative exhaust air preheating . Papierflieger-Verlag Clausthal-Zellerfeld 2015, ISBN 978-3-86948-425-9 , p. 16.
  3. ↑ Werner Zandler, M. Dertinger: Extension of the field of application of regenerative thermal exhaust gas cleaning. In: Commission for keeping the air clean in the VDI and DIN (ed.): Advances in air pollution control technology - optimization of production-integrated environmental protection and exhaust gas cleaning. VDI-Verlag Düsseldorf 1999, ISBN 3-18-09-51478 , p. 179.
  4. ↑ Torsten Reindorf: Modeling and analysis of the operating behavior of thermal post-combustion systems with regenerative exhaust air preheating . Papierflieger-Verlag Clausthal-Zellerfeld 2015, ISBN 978-3-86948-425-9 , p. 18.
  5. ^ A b c d Franz Joseph Dreyhaupt (editor): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , pp. 839-840.
  6. ↑ a b c Torsten Reindorf: Modeling and analysis of the operating behavior of thermal post-combustion systems with regenerative exhaust air preheating . Papierflieger-Verlag Clausthal-Zellerfeld 2015, ISBN 978-3-86948-425-9 , p. 1.
  7. ↑ a b VDI 2442: 2014-02 exhaust gas cleaning; Process and technology of thermal exhaust gas cleaning. Beuth Verlag, Berlin. P. 26.
  8. ↑ VDI 3896: 2015-10 Emission Reduction; Preparation of biogas to natural gas quality (Emission control; Preparation of biogas to natural gas quality). Beuth Verlag, Berlin. P. 26.
  9. ↑ Kai-Uwe Heyer, Karsten Hupe, Rainer Stegmann: Landfill ventilation for climate protection. In: Hazardous substances - cleanliness. Air. 76, No. 5, 2016, ISSN  0949-8036 , pp. 159-163.
  10. ↑ VDI 3475 sheet 3: 2006-12 emission reduction; Systems for the mechanical-biological treatment of municipal waste (emission control; Mechnical-biological treatment facilities for municipal solid waste). Beuth Verlag, Berlin. P. 90.
  11. ↑ VDI 2442: 2014-02 exhaust gas cleaning; Process and technology of thermal exhaust gas cleaning. Beuth Verlag, Berlin. P. 48.
  12. ↑ VDI 3893: 2011-05 Emission Reduction; Systems for roasting cocoa and for the production of chocolate masses (Emission control; Installations for roasting cocoa and producing chocolate liquor). Beuth Verlag, Berlin. P. 14.