Patent ID: 8735517

Claim:
A stirred tank polymerization reactor system comprising: a tank; a stirring assembly including a rotatable shaft that extends through a wall of the tank; a seal including an outer cylinder mounted in the wall of the tank, an inner cylinder that is rotatable relative to the outer cylinder and connected to the shaft, and first, second, and third fluid barrier seals mounted between the outer and inner cylinder at different positions along the axis of rotation of the inner cylinder with the first fluid barrier seal being closest to the tank interior; and first and second sources of pressurized barrier fluid connected between said first and second pressure fluid barrier seals and said second and third barrier seals, respectively, wherein the first barrier fluid source supplies barrier fluid at a higher pressure than a maximum pressure within the tank, and said second barrier fluid source supplies barrier fluid at about 40%-60% of the pressure of the first barrier fluid; and wherein the first and second barrier fluid sources each supply barrier fluid at pressures such that sealing friction forces applied to the second and third fluid barrier seals differ by no more than 20% of the higher sealing friction force.