Tank CIP Vortex Control
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Prior to 1990 ESC affiliates actively engaged in CIP engineering work in the Pharmaceutical or Biotech industries had not encountered the vortex phenomenon encountered when removing flush, wash and rinse solutions from dish-bottom center outlet type tanks; i.e., specifically the ASME rated pressure/vacuum vessel. Work in IV solutions in the late 70’s had involved only RIP and SIP practices, and return flow problems would not have been recognized lacking a need to establish and maintain recirculation at low levels in the tank.
Two of three early projects that included the application of dairy-type single-tank single-use CIP skids were engineered to existing dairy practices which applied 2” CIP piping for all flows between 45 and 100 Gpm, and the vessels fitted with 2” outlet valves and cleaned at 45 Gpm did not create this problem. The third project, a mid-80’s blood fractionation process used dairy-type atmospheric vessels with flat bottoms pitched to pods, combined with a SUEA CIP skid, and thus no problem.
And then, in 1992 an application of a SUEA on vessels that required CIP flow rates of 60 Gpm focused attention on the cause of a substantial problem. ESC designed and installed a SUEA Test Apparatus to investigate the operating conditions, using a dairy-type SUEA skid waiting for shipment to a delayed installation project.
Two test vessels, one with ASME dish top and bottom heads, and one with a dairy-type flat bottom pitched to pod outlet were set side-by-side, and connected to the SUEA skid with single-line, loop-type and internal-tube headers, selected and applied via two U-Bend Transfer Panels. The test tank with the dish bottom had a 2” outlet for which spool adapters were fabricated to simulate 1” and 1-1/2” outlets in addition to the 2″ nozzle.
The test sprays were drilled for downwards coverage directed to the sidewall to enable visual observation and video-taping of the outlet conditions.
The SUEA CIP Skid was uniquely applicable to this test purpose for it would operate on a minimal volume of water but would fail COMPLETELY, and immediately, if CIP return flow failed to equal the supply flow. The procedure was simple to understand, and apply.
(1) The selected tank was connected via the desired headers to the SUEA CIP skid.
(2) The selected outlet configuration would be established; i.e., size and type vortex breaker, if any.
(3) The SUEA skid would be filled with a volume of water equal to (a) 14 gallons for the Air Separation Tank plus (b) the volume required to fill the CIPS piping, (c) one-half the volume required to fill the CIPR piping, and (d) one gallon for a minimal tank puddle during CIP recirculation.
(4) The SUEA would be made operative at or below the desired operating flow rate. If return flow was impeded by any vortex development, the water would begin to accumulate in the test tank, causing the level in the SUEA Air Separation Tank column to fall and at a certain point, the CIP pump would air-lock and flow would stop.
The results are summarized and put to practice on the following slides. This information and other data about split-flow in loop-type and internal-tube headers, dead-leg lengths and positions, CIPS Air-Blow of loop-type headers, and the impact of CIPR side air incorporation on performance of standard centrifugal pumps in SUEA based systems (NONE), was shared with the entire industry at ASME and SBP CIP Symposiums during the 1992-2004 period.