Gas purification techniques

Photo oxidation

• Direct photolysis: Components which absorb good in the used golf length area (certain
  VOS, NH₃, H₂S, mercapthane, amines) can be demolished directly under the influence of UV-C
  radiation (fotolyse). Possibly acting photolysereactions are: 
  C₂H₆ + hv   --> CH₃ + HC + 2 H
  H2S  + hv   --> H + HS 

• Oxidation by reactive oxygen radicals: Components which do not absorb UV-radiation directly, as well as response products of the photolysis reactions, are able be oxidized by high reactive oxygen radicals. These lasts are formed with reaction of UV-radiation on oxygen presently in the gas flow, according to following responses:
  3 O₂ + hv  --> 2 O₃
  O₃    + hv --> O2 + O * 

At these oxidation reaction become CO₂, H₂O, N₂, SO₂ formed as end products. photograph foto oxidation is very suitable for discontinue processes with lower solvent concentrations (maximum 500 mg/m³). Obtain the process, as it happens, without delay its steady-state disposal output and have no extra boot cost or lose with respect to ongoing functioning.

After UV-oxidation unit some suppliers still place a catalyst (active carbon) to complete the oxidation process and so that the non reacted ozone can convert to oxygen. Other suppliers offer to the possibility to place after the 1st set of lamps a 2nd set of lamps with another wave length, with the intention to convert the non reacted ozone.
Sometimes two oxidation units are placed in serial , with in between a catalyst (silica gel). With this u can treat the concentration peaks and the short polar VOC connections more efficiently . At strongly polluting gas flows and degassing on higher temperature (50 - 200 °C) the photo oxidation can be placed in the side flows if the engine can endure a maximum of 60 °C. There no direct photolysis step on but radicals
(oxygen, hydroxyl) are formed. These radicals are injected in the main stream where they oxidize the
fragrance molecules and hydrocarbons. Functioning in the side flow is generally less efficient than direct
photo oxidation. Feasibility tests have been designated retrieve the output.
The advantages of photograph oxidation are:

• Compactly, modular system

• Placeable both in- and outside

• To turn on/off to need (small boot time)

• the process takes place at low temperature.

• low energy usage in comparison with afterburners (for gas flows
  with low energy-contends)

• Low noise

The disadvantages are:

• A preceding test has been designated to examine if technique is
  arranged for a specific installation.

• Not arranged for disposal of high VOC concentrations (> 500 mg/m³).
  

Foto oxidation is very suitable for discontinue processes with
lower solvent concentrations (maximum 500 mg/Nm³). The process obtains , as it happens, without delay its steady-state
disposal output and have no extra boot costs or lose with respect
to ongoing functioning.
photograph oxidation is nowadays mainly applied in the following
sectors:

• Coatings installations (fox reduction)

• Water purification installations (fragrance suppression)

• Garbage sorting installations (fragrance suppression)

• fermentation processes, breweries (fragrance suppression)

• feeding industry (meat, fish) (fragrance suppression)

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