Acid vapor control in aluminum anodizing industry and designing a proper ventilation system

Subject Areas : environmental management

Seyed Mostafa  Khezri ¹ (1- Faculty of Environment and Energy, Science and Research Branch, Islamic Azad University)
Nabiollah  Mansuri ² (Faculty of Environment and Energy, Science and Research Branch, Islamic Azad University)
Farideh  Atabi ³ (Faculty of Environment and Energy, Science and Research Branch, Islamic Azad University)
Azadeh  Sedghinia ⁴ (Faculty of Environment and Energy, Science and Research Branch, Islamic Azad University)

Received: 2007-12-11 Accepted : 2008-03-11 Published : 2009-12-22

Keywords: Aluminum Anodizing, Sulfuric acid, local ventilation system, actual volumetric&#x0D, &#x0D, , Scrubber,

Abstract :

Parallel with man’s achievements in different aspects of technology, aluminum anodizing industry has improved a lot, but like other progressive industries, it has caused destructive effects on the environment, as well. In fact, aluminum anodizing industry is hazardous because it requires contact with sulfuric acid. The aim of the present study was to control sulfuric acid mist during the process of aluminum anodizing in a factory located in Alborz Industrial Estate. Following sampling, it was found that the concentration of sulfuric acid mists was 8 times higher than the standard level (standard level: 1mg/m3). In order to control the diffusion of sulfuric acid mist in the workshops and the areas where the workers breathe, a local ventilation system, based on the velocity-pressure method and according to the balancing of branches, was put into operation. The implemented hood was chosen based on the standards stated in the American Conference of Governmental Industrial Hygienists (ACGIH) guidelines. And the rate of required standard volumetric flow (scfm) for open-surface tanks was calculated to be equal to 1050 ft3/min for each hood. Consequently, based on the psychometric status of the studied workshop and the actual volumetric flow rate, the rate of required volumetric flow for each hood was considered to be 1239cfm. The whole system was divided into four independent ventilation units, two of which were equipped with 12 hoods (9 with unidirectional suction and 3 with bidirectional suction) and the others with 9 hoods (all with unidirectional suction). In order to resist against corrosion, steel 316 was selected as the constructing material of the canals, and in order to purify the exhaust air, following the necessary evaluations, mist eliminator scrubber system was selected. Also, to provide the required driving force, Back Ward centrifugal fan was considered.