AC Variable Speed Motor Driven Pre-Expander is provided with double expansion system. The Pre-Expander is offered with AC variable speed motor and steam pressure relief valve provided to control density. The Pre-Expander has the inner shell made of stainless steel with insulation from outside to control energy waste. AC Variable Speed Motor Driven Pre-Expander is available with fluidized-bed-drier along with sieving unit and blower for conveying dry material to the silos