Patent ID: 7600960

Claim:
A method for transfer of a particulate product between two zones with different pressures, P 1 and P 2 , respectively, the method comprising: conducting the product from the first pressure zone through a portioning device which produces uniform product portions, and thereupon conveying the product portions individually through a sluice device, which comprises at least one chamber and two pressure locks, force loading the product portions from the first pressure zone into said chamber by means of a piston screw, the axis of which is practically in line with the axis of the chamber, compressing the product during the transfer from the first pressure zone to the second pressure zone, force unloading the product portions from the chamber and into the second pressure zone by means selected from the group consisting of: said piston screw, a piston, and a supply of gas, steam or liquid supplied at a pressure higher than that of the second pressure zone, dividing the uniform product portions by uniform particle free spaces, so as to secure that no particles occur in working spaces of the pressure locks when the pressure locks are closing, securing a pressure tight barrier between the two pressure zones at any time by at least one of the pressure locks, providing said chamber in the form of a sluice chamber, changing the pressure in the sluice chamber from P 1 to P 2 when a product portion is present in the sluice chamber and both pressure locks are closed, changing the pressure in the sluice chamber from P 2 to P 1 when a product portion has been unloaded from the sluice chamber and both pressure locks are closed.