Sulphur grinding being explosive in nature, we have considered our modified High Pressure Air Classifying Mill ( Suitable for 2.5 Bar pressure ) with a closed Loop System with N2 Purging as a carrier Gas being Inert in Nature is used. Bag Filter of High Pressure design i.e. suitable for 2.5 bar pressure considered. Product Contact Parts are in SS 304 MoC

N2 purging in the System becomes essential to avoid explosion fire hazard due to O2 Content existing in the system. In order to ensure safe working of the system the O2 level in the system is to be maintained below 8% V/V. The percentage of O2 in the system is measured by an Oxygen Analyzer installed at the entry of the Mill.

To avoid Polymerization of Sulphur & any hazard due to the effect of Temperature, the Temperature of the system is to be maintained at less than 10 0C & the Temp. of the gas at the inlet of Mill is to be maintained at 50C. To achieve this a Heat Exchanger is considered at the Mill Inlet. In addition to this injection of liquid Nitrogen as make up Quantity to limit Temp rise in the Mill is provided.

Further the Bag Filter is equipped with Polyester Antistatic Bags and earthing Studs in order to dissipate any Static Charge developed during the process. The Bag Filter is also equipped with Rupture Disc to protect it from any possible explosion. The bag Cleaning is achieved by using compressed N2. Required Instrumentation to measure Pr., Temp., & Flow for smooth running of the Plant are considered in our Scope. Also considering sticky nature of ground Sulphur, we have considered Bag Filter hopper in SS-304 moc with buffing & having 70 Deg. Valley angle to facilitate smooth sliding of the ground powder.

WORKING OF THE PLANT : -

Nitrogen from the N2 Plant is circulated throughout the system by means of a Fan before starting the mill. This is essential to reduce the existing Oxygen level within permissible limits. In addition, this also assists in bringing down the temperature of the gas in the system by passing it through the heat exchanger provided at the mill inlet. The pressure at the inlet and outlet of the fan maintained in such a way that it avoids any leakage of atmospheric air into the system leading to increase in O2 content within the system. Also to avoid leakages from Fan, Lybrinth Seals are considered with Pneumatic air supply. Once the above parameters are under control, i.e. they are under the safe permissible limits, the material is fed into the mill through the Rotary Airlock Valve below the additional Feed Hopper provided above the mill. Once the required fineness is achieved the material is sucked into the Bag Filter by means of the same fan. The filter bags are to be cleaned using N2 gas. The material is then discharged through the hopper having valley angle of 70o through a Rotary Airlock Valve.

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