The Plants supplied by Vivex Engineering Ltd.

Project in Urban Solid Waste

Principle of working Process:For the specific performance we offer a Double-Step treatment :

• With bio-oxidation & • With ferric regenerative

In the first step the acid fumes are in close contact with a water solution of sodium hydroxide in special wet scrubber.

In this scrubber the reactions is : H2S + 2NaOH -> Na2S + 2H2O

At the exit of first step the acid fume can have a little quantity of H2S.

In the second step the acid fume are in close contact with a water solution of ferric hydroxide in special wet scrubber.

In this scrubber the reactions is : 3H2S + 2Fe(OH)3 -> Fe2S3 + 3H2O

So, in the reactor the hydroxide is regenerated and the sulphur is free as cluster in the mixed water.

The acid fume outlet from the second step can have as H2S < 10 ppmV and a little reduction of carbon dioxide.

PROJECT DATA of ONGC:

-Acid fume flow 29,200 Nm3/h (0.7 mmscmd)-Temperature +35 - +50 °C- Inlet pressure 0.96 to 1.06 kg/cm2-Inlet H2S 6000 to 12,000 ppmV maximum-Inlet H2O 3 to 8 %-Inlet CO2 95 to 98 %-Other 1 to 1.5 %

GUARANTEES & LIMITS OF TREATMENT

The plant, on the base of the data of project assumed, it will guarantee followingPerformance:

• H2S in vent gas <10 ppmV• Sulphur purity > 98 %• Sulphur produced > 80 % of H2S inlet( i.e. with inlet H2S = 12,000 ppmV, the sulphur Can be around 420 kg/h)

Technical Details: The followings data are valid for H2S inlet of 12,000 ppmV and flow rate of 29,000Nm3/h of acid gas and for running 24/24 for 365 d/y.

PRODUCTSulphur with purity > 98 % Quantity: 3,680,000 kg/year

CHEMICAL / CONSUMABLE REQUIRED

- Ammonium chloride 250,000 to 350,000 kg/year + water- Phosphoric acid 50,000 to 75,000 kg/year + water- Ferric chloride 50,000 to 200,000 kg/year + water - Sodium hydroxide 250,000 to 500,000 kg/year + water- Electric power 270,000 kWh/year- Water 2000 to 3500 m3/year- Biomass for biofilter 2 to 4 m3/year

System Features:

• Effluent Not present• Reduction of H2S ≤ 10 ppm at outlet• Purity of Sulphur > 98%• Freely selection of equivalent chemicals for cost reduction.• NaOH can be substitute with CaOH2 or KOH• Amonium Chloride can be substitute with UREA• Phosphoric Acid can be substitute with Sodium Phosphate or Calcium Phosphate.• Minimum Maintenance• Only 2 - 3 % biomass replacement required per annum