Steam Sterilization Cycle Modeling and Optimization for

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Steam Sterilization Cycle Modeling and
Optimization for

• TEAM MEMBERS
• Jared Humphreys
• Mike Arena
• Matt Lototski
• John Chaplin
• Colin Bradley

ADVISOR Greg Kowalski
SPONSOR - MICROFLUIDICS Mimi Panagiotou Dan
Dalessio
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Background

• ? Manufacture machines called Microfluidizers
• ? These machines force product through fixed
  geometry micro-channels using intense pressure
• ? Product goes in as random large particles and
  exits as uniformly sized nanoparticles

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Background

• ? Used in a growing number of pharmaceutical,
  personal care, biotechnology, food and chemical
  applications
• ? System must be sterilized between each
  processing session to ensure purity of product
• ? Sterilization cycle is multi-staged and time
  consuming
• ? Wetted surface must be exposed to steam at
  121C for at least 20 minutes per ASME BPE-a-2004
  requirements

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Competitive Technology

• High Shear Dispersers
• Pulverizing Mills
• Coaxial Mixers
• Planetary Ball Mill
• Not capable of achieving uniform nano-level
  particles

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Project Goals
FAILING SEAL WITHIN INTENSIFIER PUMPS

• To verify that all sections of the system which
  come in contact with the product are heated to
  121C or higher for at least 20 minutes during
  the steam sterilization cycle
• Find a solution to stop the intensifier pump seal
  failure

Failing Seal
Piston
Product Chamber
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Operation Sequences

• 1. Prime the machine
• Use WFI, USP Purified Water, Product or other
  process compatible fluid
• 2. Process Product
• 3. Clean in Place
• 4. Steam in Place
• 5. Cool Down

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Steam in Place Process

• ? Steam in Place 3 Stages
• ? Heat product wetted piping and outside of
  chambers first
• ? Saturated steam from boiler at 138 C and 35
  psig is passed through the system
• ? Temperature and pressure are monitored at the
  system inlet and outlet

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Intensifier Pump Process
Step 1
Seal
Check Valve 1
Piston
Step 2
Check Valve 2
To Chambers
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Seal Failure

• Seal failure method thermal degradation
• Seal material TIVAR H.O.T.
• Maximum seal operating temperature 135C
• Excessive temperature exposure or thermal cycling
  causes the seal to crack and become softer

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Deliverables

• ? Computer simulation of steam in using
  computational fluid dynamics software (Fluent)
• ? Analysis of simulation to determine that
  current process complies with ASME sterilization
  requirements
• ? Recommendations of changes to current process
  to eliminate seal failure

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Solidworks Model

• ? Extremely complex
• ? Incompatible with Fluent analysis as-is
• ? Many components needed to be remodeled with
  interior flow path defined (heat exchangers,
  pumps, valves)

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Area of Concern
Temperature and Pressure Sensors

• Focus area of current system successfully modeled
  in Solidworks
• File imported to Gambit for 3D meshing and
  subsequent Fluent Analysis
• Determined temperature around the seals to aid
  design solutions

Intensifier Pumps
Chambers
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Pressure Outlet Calculations
P1 inlet pressure P2 outlet pressure µ
viscosity V velocity D Diameter L length
of chambers
P1-P2 (64µVL)/(2D2) P1-0 (64)(0.000013
Ns/m2)(7.4 m/s)(.3 m)/(2)(0.000078m)2 P1
151,794 Pa
P1V1P2V2 (35psig)(1.1in2)P2(13.81in2) P2
2.95 psi Draw Pressure
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CFD Analysis
Saturated Steam T1 411 K (138 C) P1 241300 Pa
(35 psig)
Pipe Sections 316L Stainless Steel
Seal Location (Inside Pump)
Tamb 298.1 K h 6 w/m2-K
P3 221310 Pa
P4 221310 Pa
P2 151000 Pa
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GAMBIT Mesh
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Static Pressure (Pa)
P1 241300 Pa
P3 221310 Pa
P4 221310 Pa
P2 151000 Pa
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Static Temperature (K)
Seal Temperatures 408 K (135 C)
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Velocity (m/s)
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Reynolds Number
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Thermal Verification

• mass flow rate m ?VA
• m (.546 kg/m³)(300 m/s)(.000792 m²)
• m .192 kg/s
• Heat Loss q mCpTin - Tout
• hAsTave - T8
• q (.129 kg/s)(2.0133 Ws/kgK)(408.1 - 407.9 K)
  .026 Watts
• q (6 W/m²)(.00374 m²)(407.95 - 298.1 K) .024
  Watts

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Proposed Solution

• By decreasing inlet temperature 5, seal
  temperatures are well below limits (130 C max)
• Transient analysis shows inlet temperature
  adjustment does not significantly affect warm-up
  time
• Does not require any modification to current
  system design

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Static Temperature (K)
Decreased Inlet Temp 406 K (133C)
Seal Temperatures 403 K (130C)
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Future Work

• Remodel pump chambers in GAMBIT to enable
  analysis with piston motion simulated
• Model remaining steam phases to ensure reduced
  steam temperature can be used throughout entire
  sterilization process

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Questions?