STTR Detail

The smaller GREEN diagram illustrates all Rinse to Drain steps.  The larger RED diagram illustrates the recirculation steps through the Water Tank for chemical addition, heating, and alkaline or acid washes for all circuits, i.e., Vessels, Lines, or both.  See scroll box below for additional information.

STTR Schematic

Normal (or Suggested) Sequence of Operation

  1. Control system confirmation of all interlocks and enabled conditions related to the selected circuit, including CIPS/R valves, vessel valves, etc.
  2. Water Tank Fill – The AWFI valve will be energized open and the level sensor will monitor tank level.  The tank will be filled to the high level and the valve will  close, allowing step advance.
  3. Pre-Rinse – The TOV will open, admitting water to the CIPS pump.  Following a brief delay for water to fill the pump casing, the pump will start and as water passes the FE (Flow Element), (a) the flow control loop will adjust the pump speed to deliver the desired Gpm/Lpm and (b) a flow totalizing register will accumulate pulses representing the rinse volume  When the stored rinse volume setpoint is reached, the pump will stop.  When the LS senses a slightly lower level, the AWFI valve will open to keep the tank full, under LS control.  The water will move through the distribution piping to and through the circuit, and return to the DRAIN valve  to the facility waste system.  When it reaches The RET (Return Probe) the probe will sense return flow and confirm the integrity of the CIP/R path, allowing step advance.  A suggested Line circuit rinse volume is 1.5 times the volume of the circuit piping, plus the CIPS/R piping.  Some software documentation will show this as two steps.
  4. Establish Recirculation – The DRAIN valve will close and the TANK RECYCLE valve will Open. The LS will confirm adequate level for recirculation, adding water if needed. A WAIT will occur for confirmation of Supply Pressure by the PS and Supply Flow by the FE.
  5. Heat and Alkali Feed – Steam will be admitted to the HXR and the required amount of alkali will be introduced to the chemical feed slip stream by weight, volume or time.
  6. Delay to Return Temperature – A Wait for the recirculating solution to reach setpoint temperature, monitored by the CIPS RTD.
  7. Alkali Conductivity Test – The COND sensor will be enabled to confirm addition of the required amount of alkali.
  8. Alkaline Wash– When temperature and conductivity are satisfied a flow totalizing register will accumulate pulses representing the Alkaline Wash volume  When the stored Alkaline Wash volume is reached, (a) the pump will stop, (b) the Drain Valve will open and (c) the Return valve will close. The CIPR motive means will discharge the wash solution to waste.

(to be continued DAS 2/18/2013)