Iran Occupational Health

Background and aims: Steel industry plays an important role in air pollution and particulate emissions released to the environment. The Venturi scrubber is one of the most important scrubbers and components at local exhaust ventilation which has a lot of application to control of the contaminants emissions to the atmosphere in the steel industry. On the other hand, the efficiency of this equipment depends to use and how to use, therefore aim of this study is determination of the efficiency of a venturi scrubber at an iron making unit.

Methods: This research is a descriptive cross-sectional study to determination of the venturi scrubbers efficiency in collection of particle different sizes. Sampling to be fulfilled based on BS 3405 method and duct internal isokinetic sampling at 30 l/min flow before and after venturi scrubber using of the sampling sequence include a set of probe with standard inlet nozzle, sampler and particles classifier (the four-stage cascade impactor) which followed with the flow control and measurement equipment. Finally, the samples were analyzed using gravimetric method and the results were analyzed using spss 16 Software.

Results: The fluid velocity was in the throat of the scrubber 71.4 m/s and the ratio of liquid to gas 1.12 l/m³. The mean of total dust concentration was before and after Venturi, respectively 6900mg/m³ and 983mg/m³. The overall efficiency of the venturi scrubber was 85.3%. The maximum removal of the particle size distribution was respectively to particle size 15μm<, 15-4μm, 4-1μm and <1μm  and 93.2%, 90.6%, 79.4%, 30.4%.

Conclusion: It is concluded that scrubber’s efficiency increased in parallel increasing in particle aerodynamic diameter, but its removal efficiency was not achieved to desirable level for particle size lower than 1 μm because of inappropriate modification in some design parameters such as nozzles. Regarding decrease in load pollutant input, performance of this scrubber is not acceptable even for large particle sizes.