Basically, the cleaning of gases by thermal oxidation consists in submitting them to a sufficiently high temperature during the necessary time to produce the oxidation of the contaminants. Therefore, to achieve an effective cleaning, it is necessary to combine temperature (between 750 and 1200 ºC), during a minimum of time to complete the oxidation reaction, with turbulence in the gases that allows a perfect mixture of all its components.
These conditions are achieved inside an oxidation chamber designed for this purpose, equipped with a conical air vein burner that uses the gas to be clean as combustion air. This way, the energy necessary for the cleaning process is minimized as far as possible.
This technique is used to eliminate both organic (solvents, odors ...) and inorganic compounds (CO, SH2, NH3 ...). It is frequently used in situations where the gas flow is small but the concentration of pollutant is relatively high (up to 20 g / Nm³ of total organic carbon).
The oxidation of undesirable gaseous compounds is a satisfactory method of contaminants control, from several aspects:
Almost all highly odorous contaminants are combustible or are transformed into less odorous substances when heated to a sufficiently high temperature in the presence of oxygen. Among the odorous pollutants in the air, destroyed by thermal oxidation, mercaptans, cyanide gases and hydrogen sulfide are included.
Organic sprays that cause visible plumes are effectively destroyed by combustion. Coffee roasters, meat smokers, and glaze baking stoves emit such aerosols.
Some organic gases and vapors, if discharged into the atmosphere, are involved in photochemical oxidation reactions. The combustion effectively destroys that compounds.
Some industries, such as refineries, produce large quantities of highly combustible waste gases and organic materials that are otherwise dangerous. Generally, the safest method to control the effluent is by combustion in furnaces specially designed for that purpose.
As the temperature of the gases leaving the oxidation chamber is very high, it is necessary to recover its energy by procedures such as the preheating of the gas to be clean, water steam generation or the heating of thermal oil. If the concentration of organic pollutants is high, these plants are convenient because they allow to use the oxidation heat of the contaminants in the industrial process.
Each recuperative plant is custom designed to adapt it as much as possible to the client's process.
This equipments main features are:
Very high efficiency
Relative flexibility in terms of flow variations (from 1 to 3)
Possibility of energy recovery of waste gas
High energy cost of operation if the pollutant concentrations are low
Thermal oxidation plant to clean gases coming from a cataphoresis furnace.
It has two heat exchangers: one to preheat the gases to be cleaned and another to
heat ambient air that is introduced into the cataphoresis oven.