Depending on the Volume, composition, and concentration of the VOCs,if the volume is small (normally less than 10000Nm3/h) and concentration is high(Calorific value is more than 1000Kcal/Nm3), then the first choice is thermal oxidizer(TO). If the volume is large(more than 5000m3/h) and concentration is small (normally less than 5000mg/m3),then regenerative thermal oxidizer will be considered. If the volume is huge(normally than 50000m3/h) and concentration is little( less than 400ppm), concentration will be choiced. Catalyst oxidizer will be considered if there is no halogen, sulphur contained and volume is not high (less than 30000m3/h) and concentration is suitable(adiabatic temperature rise is less than 300℃).