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Published byVernon Sims Modified over 2 years ago

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Steam Sterilization Cycle Modeling and Optimization for T EAM M EMBERS Jared Humphreys Mike Arena Matt Lototski John Chaplin Colin Bradley A DVISOR Greg Kowalski S PONSOR - M ICROFLUIDICS 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 121°C 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 To verify that all sections of the system which come in contact with the product are heated to 121°C or higher for at least 20 minutes during the steam sterilization cycle Find a solution to stop the intensifier pump seal failure Product Chamber Piston Failing Seal FAILING SEAL WITHIN INTENSIFIER PUMPS

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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 Piston Check Valve #1 Check Valve #2 Seal To Chambers Step 1 Step 2

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Seal Failure Seal failure method “thermal degradation” Seal material: TIVAR H.O.T. Maximum seal operating temperature: 135°C 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 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 Temperature and Pressure Sensors Intensifier Pumps Chambers

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Pressure Outlet Calculations P1-P2 = (64*μ*V*L)/(2*D2) P1-0 = [(64)*(0.000013 Ns/m2)*(7.4 m/s)*(.3 m)]/[(2)*(0.000078m)2] P1 = 151,794 Pa P1 = inlet pressure P2 = outlet pressure μ = viscosity V = velocity D = Diameter L = length of chambers P1*V1=P2*V2 (35psig)(1.1in^2)=P2(13.81in^2) P2 = 2.95 psi Draw Pressure

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Saturated Steam T 1 = 411 K (138 C) P 1 = 241300 Pa (35 psig) T amb = 298.1 K h = 6 w/m 2 -K P 2 = 151000 Pa Pipe Sections 316L Stainless Steel CFD Analysis P 4 = 221310 Pa P 3 = 221310 Pa Seal Location (Inside Pump)

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GAMBIT Mesh

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Static Pressure (Pa) P 2 = 151000 Pa P 4 = 221310 Pa P 3 = 221310 Pa P 1 = 241300 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 = ρ·V·A m = (.546 kg/m³)(300 m/s)(.000792 m²) m =.192 kg/s Heat Loss = q = m·Cp·[T in - T out ] = h·A s ·[T ave - T ∞ ] 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 (133°C) Seal Temperatures ~403 K (130 ° C)

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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?

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