Solid bowl centrifuge with air circulation control

Claim 1

IN A CENTRIFUGE FOR CONTINUOUS SEPARATION OF SOLIDS AND LIQUIDS FROM SLURRY, COMPRISING AN OUTER HOUSING INCLUDING A CENTRAL CASING PORTION, A SOLIDS COLLECTION CHAMBER AND SOLIDS DISCHARGE OUTLET PORTION AT ONE END OF THE CASING, AND A LIQUID COLLECTION CHAMBER AND LIQUID DISCHARGE OUTLET PORTION AT THE OTHER END OF THE CASING, A SOLID-WALLED BOWL MOUNTED FOR ROTATION ABOUT AN CENTRAL AXIS IN SAID HOUSING AND ADAPTED CONTINUOUSLY TO RECEIVE SLURRY TO BE SEPARATED, THE SLURRY UPON ROTATION OF SAID BOWL FORMING AN ANNULAR POOL THEREIN, A CONVEYOR MEMBER MOUNTED WITHIN SAID BOWL FOR CONCENTRIC ROTATION THEREWITH AT A SPEED DIFFERENT FROM THE BOWL TO WORK SOLIDS FROM THE POOL OF SLURRY TOWARD A FIRST END OF THE BOWL FOR DISCHARGE THEREFROM INTO SAID SOLIDS COLLECTION CHAMBER OF SAID HOUSING, SOLIDS DISCHARGE MEANS AT THAT END OF THE BOWL OVER WHICH SOLID ARE CONVEYED FROM SAID BOWL TO SAID SOLIDS COLLECTION CHAMBER AND OUTLET, AND LIQUID OUTLET MEANS AT THE OTHER END OF THE BOWL, LOCATED WITHIN THE LIQUID COLLECTION CHAMBER OF SAID HOUSING AND OVER WHICH LIQUID FLOWS FROM THE ANNULAR POOL IN SAID BOWL TO SAID LIQUID COLLECTION CHAMBER AND OUTLET, SAID LIQUID OUTLET MEANS BEING DISPOSED AT A LARGER RADIUS OF SAID BOWL THAN SAID SOLIDS DISCHARGE MEANS; THAT IMPROVEMENT COMPRISING A GAS RECIRCULATION PIPE, SAID PIPE BEING CONNECTED AT ONE END AND OPENING INTO SAID LIQUID OUTLET OUTSIDE OF THE CONFINES OF SAID BOWL AND NEAR SAID LIQUID COLLECTION CHAMBER IN AN AREA OF SAID OUTLET SUBSTANTIALLY LIQUID-FREE AND OPEN TO THE PRESURE OF GAS IN SAID LIQUID COLLECTION CHAMBER, SAID PIPE BEING CONNECTED AT ITS OTHER END AND OPENING INTO A PORTION OF SAID HOUSING REMOTE FROM SAID LIQUID COLLECTION CHAMBER AND OUTSIDE OF THE CONFINES OF SAID BOWL IN AN AREA OPEN TO GAS PRESSURE IN SAID HOUSING RELATIVELY LOWER THAN THE GAS PRESSURE IN SAID LIQUID COLLECTION CHAMBER, WHEREBY GAS FLOW IN THE DIRECTION FROM SAID LIQUID COLLECTION CHAMBER TOWARD THE AREA OF RELATIVELY LOWER PRESSURE IN SAID HOUSING OCCURS SUBSTANTIALLY WHOLLY IN SAID RECIRCULATION PIPE.