Master Brewer Program (6 Weeks)

• Fluids fundamentals and equipment.

• Fluids test. Heat transfer fundamentals and equipment.

• Heat transfer test. Insulation, steam, refrigeration.

• Heat exchanger/steam/refrigeration test. Materials, process control.

• Materials and process control test. Instrumentation, pasteurization, filtration and process gases.

• Instrumentation, pasteurization, filtration and process gas test. Wrap-up.

How this Relates to the IBD Syllabus3.1 Packaging Materials3.2 Unit Packaging Operations3.3 Sterile Filtration and Pasteurization3.4 Packaging Line Design3.5 Quality3.6 Process Gases3.7 Fluid Flow3.8 Principles of Heat Transfer3.9 Steam3.10 Refrigeration3.11 Materials of Construction3.12 Process Control and Instrumentation

So, what do we need to know about fluids

3.7.1 Forms of fluid and fluid energy

3.7.2 Properties of moving fluids

3.7.3 Friction loss

3.7.4 Pumps

3.7.5 System design

3.7.6 Cavitation and NPSH

3.7.7 Valves

Qualitative and Quantitative

• Liquids – take shape of container, but have finite volume (incompressible)

• Gases – are compressible, take size and shape of container

• Shear force will always deform a fluid

• Mass and volume flow rates

• Newtonian Fluid – Shear resistance proportional to relative velocity between fluid layers

• Newtonian – Water, air, beer

• Non-Newtonian – Gelatin, blood, milk, mash, wort

Example: Water with density of 1000 kg/m3 flows through a 10.0 cm diameter pipe at a velocity of 5 m/s. The pipe size is then reduced to a 5.0 cm diameter. Determine the mass and volumetric flow rates and the velocity of the water in the 5.0 cm pipe.

Bernulli’s equation:

Applications• No-flow• Flow through orifice plate, venturi meter

“Head” = Pressure

Determine the absoluteP in the tank using themanometer (water)

constant2

1 2 gzvP

ghP

PTank

18 cm

Fluid Statics

Example: Water fills a 10 m deep tank with a 10 cm diameter butterfly valve at the bottom. Calculate the gauge pressure at the valve and the force acting on the valve, assuming that it is round.

Example: Water with density of 1000 kg/m3 flows through a 10.0 cm diameter pipe at a velocity of 5 m/s. The pipe size is then reduced to a 5.0 cm diameter. Determine the mass and volumetric flow rates and the velocity of the water in the 5.0 cm pipe.

atmgaugeabs PPP AFP

Reynolds NumberLaminar flow - “low” flow rates, viscous forces most significantTurbulent flow - “high” flow rates, inertial

forces most significant

Re < 2300 Laminar2300 < Re < 5000 TransitionalRe > 5000 Fully Turbulent

D

mD

4

Re

Laminar flow velocity profile (mean / max = 0.5)

Turbulent flow velocity profile (mean / max = 0.8)

22 v CD

LP f

500 gallons of wort at 70C is transferred to a boil kettle through a 25 m long, 5 cm diameter pipe. The wort flows at a velocity of 1.2 m/s, the pipe roughness is 0.005 mm the wort density is 950 kg/m3 and it’s viscosity is 0.0008 Pa.s.

a) Determine the time required to transfer all of the wort to the boil kettle, in min.

b) Determine the Reynolds Number.

c) Determine the pressure drop in the pipe.

d) Would P change if the wort were at 20C?

Example E.2

Beer flows in a straight horizontal pipeline, diameter 100 mm such that two sensitive pressure gauges 25 m apart register a pressure difference of 240 Pa (N/m2). The density of the beer is 1.001x103 kg/m3, its viscosity is 0.001 Ns/m2 and the relative roughness of the pipe is 0.0003. Calculate the velocity and volumetric flow rate of beer.

Flow Measurement – Oriface Meter

Cd accounts for frictional loss, 0.65

Simple design, fabrication

High turbulence, significant uncertainty

P1 P2

Flow Meas. – Venturi Meter

Less frictional losses, Cd 0.95

Low pressure drop, but expensive

Higher accuracy than orifice plate

P1P2

Flow MeasurementNon-Linear – Venturi, orifice, nozzle meters

4:1 Rangability

2% f.s. accuracy

Flow Meas. – Variable Area/Rotameter

Inexpensive, good flow rate indicator

Good for liquids or gases

No remote sensing, limited accuracy

WeightDragForces

mgvCdrag 2

2

10

vAV

Flow Measurement - Pitot Tube

Direct velocity measurement (not flow rate)

Measure P with gauge, transducer, or manometer

P1

P2

1 2

2

2

21v

PP

v

Flow MeasurementMagnetic – Faraday’s Law (Conductor moving

through magnetic field, voltage produced)

40:1 Rangability

0.5% of f.s. accuracy

No obstructions

Fluid must conductNo good for

• Pure water• Gases• Hydrocarbon fuels

External elec/mag fields

Flow MeasurementTurbine – magnetic pulse as turbine wheel spins

20:1 Rangability, 0.25% f.s. accuracy

Easy to interface with control system

Pumps – Add energy to liquid to move it

Pump power output =

Pump power input =

Pump power requirements includeHeight fluid must be pumpedFriction losses through fittings, equipmentVapor pressure of fluid, tank pressures

Total head, NPSH eqations

€

˙ V ΔP

€

˙ V ΔP

η

Pump Sizing Example

A pump, located at the outlet of tank A,must transfer 20 m3 of fluid into tank B in 30 minutes or less. The piperoughness is 0.005 mm, and the pumpefficiency is 55%. The fluid density is 975 kg/m3 and the viscosity is 0.00075Pa.s. The vapor pressure is 10 kPa andthe tank is at atmospheric pressure.Determine the total head, pump inputand output power and available NPSH.

Tank A

Tank B

8 m

15 m

4 m

Pipe Diameter,

25 mm

Fittings = 12 m

Centrifugal Pumps• Fluid enters at center and forced radially• Open or closed impeller

• Closed higher efficiency• Open handles solids better

Advantages• Available, cheap, adaptable, simple, reliable• Handle wide range of fluids, including solids• Discharge can be completely blocked

Disadvantages• Operate at high speed, high shear stress• Limited delivery pressure• Cannot meter flow

Positive Displacement Pumps• Reciprocating (Piston, Diaphram)• Rotary (Gear, peristaltic, lobe)

Advantages• High delivery pressure• Accurate for metering flows

Disadvantages• Pulsating delivery• Tight tolerance, so not good for solids

(except for mono pump)• Serious damage if discharge valve closed• Bigger and more costly for given application

Cavitation• Formation of bubbles• Pressure drops below vapor pressure

(friction losses)Effects

• Surface pitting and erosion• Loss of performance (changed tolerances)• High shear stresses

Particular concern when pumping wort from kettle to cooler

NPSH Required – Pump characteristicNPSH Available – Configuration characteristic

Considerations for Brewery Fluid HandlingMulti-component – sugars, proteins, etc.

Multi-phase – liquids, solids and/or gases

Biologically active – Sensitive to temperature, pressure, pH, contaminants, etc.

Sensitive to oxygen

• Surface area exposed, still or wavy

• Temperature and pressure

• Avoid less than full flow

• Avoid filling tanks from the top

Sensitive to shear forces

Centrifugal Pumps – Principle of Operation

Constantρgzρv2

1P 2

Impeller

SuctionVolute Casting

Delivery

Centrifugal Pumps – Principle of Operation

Flow accelerated (forced by impeller)

Then, flow decelerated (pressure increases)

Low pressure at center “draws” in fluid

Pump should be full of liquid at all times

Flow controlled by delivery side valve

May operate against closed valve

Seal between rotating shaft and casing

Centrifugal Pumps – Impeller Designs

Closed ImpellerMost common, few solidsWater, beer, wortFlash pasteurizationSecondary refrigerants

Open ImpellerLower pressuresSolids okayMash mixer to lauter tunLiquid yeast, wort, hops

Centrifugal Pumps

Materials - Can be made of many materialsWhat do you think is used in brewery?

Shaft seal – Must seal between rotating shaft and volute casting, effects efficiency

Hygiene Considerations – No valves, crevices, can be CIP. Mechanical seal between two faces (impeller shaft and volute casting) faces kept together with spring.

Centrifugal Pumps

Control – Valve on delivery side or change pump speed (not always available, “VFD”)

Self-Priming – Centrifugal pump will not work when “air-bound.” Can self-prime by supplying a reservoir with a “bleed supply” of liquid. Air from pipework and liquid from reservoir moves through pump until it is flooded by liquid from suction pipework. Used for CIP fluid return.

Centrifugal Pumps

Multiple pumps connected in series required for high pressures (flash pasteurization)

Curves created for specific speed, viscosity and density

Variable speed motor has same effect as impeller size

Multiple pump/impeller combinations may work

Centrifugal PumpsH-Q Chart

Head

(or P)

Volume Flow Rate

Increasing Impeller Diameter

A B C

Centrifugal PumpsH-Q Chart

Head

(or P)

Volume Flow Rate

A B C

Increasing Efficiency

Required NPSH

Centrifugal PumpsH-Q Chart

Head

(or P)

Volume Flow Rate

A B C

Centrifugal PumpsH-Q Chart

Head

(or P)

Volume Flow Rate

Required Flow

CapacityActual Flow

Capacity

Required Power

Centrifugal PumpsAdvantages

Simple construction, many materialsNo valves, can be cleaned in placeRelatively inexpensive, low maintenanceSteady delivery, versatileOperates at high speed (electric motor)Wide operating range (flow and head)

DisadvantagesMultiple stages needed for high pressuresPoor efficiency for high viscosity fluidsMust prime pump

Positive Displacement Pumps

Theory: Volume dispensed independent of delivery head

Practice: As delivery head increases, some slippage or leakage occurs

Speed used to control flow rate, use of valves could cause serious damage

Self-priming

Good for high viscosities, avoiding cavitation

Positive Displacement Pumps

Piston Pump

Volumetric Efficiency High Pressures

Metering hop compounds, detergents, sterilents

Suction Valve

Delivery Valve

Positive Displacement Pumps

Diaphragm Pump – Similar to piston pump, diaphragm contacts fluid

Not as accurate as piston pump, particles okay

Transfer trub, yeast, tank bottoms

Suction Valve

Delivery Valve

Positive Displacement PumpsPeristaltic Pump

Tubing compressed in stagesHygienic, easily cleaned (new tubing)Can be run dryLaboratory applications, sampling,

dosing

Positive Displacement Pumps

Gear Pump

High Pressures

No Pulsation

High Viscosity Fluids

No Solids

Difficult to Clean

Not common in brewery, oil feed to boiler

Positive Displacement Pumps

Lobe Rotor Pump

Both lobes driven

Can be sterilized(steam)

TransferYeastTrubBulk Sugar Syrup

Positive Displacement Pumps

Screw or Mono PumpHelical worm rotates inside elastomeric stator

Seal between worm and stator

Fluid is forced downstream

Variety of fluids, slurries.

Cannot be steam sterilized, cannot run dry

Used to transfer yeast and trub slurries

Flexible Vane Pump

Flexible rubber impeller rotates

Sampling and dosing detergents, sterilents

Centrifugal Pumps• Fluid enters at center and forced radially• Open or closed impeller

• Closed higher efficiency• Open handles solids better

Advantages• Available, cheap, adaptable, simple, reliable• Handle wide range of fluids, including solids• Discharge can be completely blocked

Disadvantages• Operate at high speed, high shear stress• Limited delivery pressure• Cannot meter flow

Positive Displacement Pumps• Reciprocating (Piston, Diaphram)• Rotary (Gear, peristaltic, lobe)

Advantages• High delivery pressure• Accurate for metering flows

Disadvantages• Pulsating delivery• Tight tolerance, so not good for solids (except

for mono pump)• Serious damage if discharge valve closed• Bigger and more costly for given application

Pump Selection Considerations• Head and flow requirements• Characteristics of fluid (density, viscosity, etc.)• Materials (sterilization, erosive nature of slurries)• Crevices where solids can accumulate• Hygienic design, seals• Pressure relief• Interchangability (spares)

Cavitation and NPSH• What causes cavitation?• What are the effects of cavitation?• Factors that cause cavitation?• NPSH Available vs. NPSH Required• Particular problems for breweries

Centrifugal Pumps

What if available NPSH is less than required NPSH?

Increase Available NPSH1. Increase suction static head (pump location)

2. Increase suction side pressure

3. Decrease fluid vapor pressure

4. Reduce friction losses on suction side

Decrease Required NPSH1. Reduce pump speed

2. Select a different pump

Valves – Globe Valve

Single Seat- Good general purpose- Good seal at shutoff

Double Seat- Higher flow rates- Poor shutoff (2 ports)

Three-way- Mixing or diverting- As disc adjusted, flow to one channel increased, flow to other decreased

Valves – Butterfly Valve

Low Cost

“Food Grade”

Poor flow control

Can be automated

Valves – Mixproof Double Seat Valve

Two separate sealing elements

Keeps fluids from mixing

Immediate indication of failure

Automated, Sanitary apps

Easier and Cheaper than using many separate valves

Valves – Gate Valve

Little flow control, simple, reliable

Valves – Ball Valve

Very little pressure loss, little flow control

Other ValvesDiaphram – Flexing membraneNon-return – Flow in one direction only

ApplicationsProduct - Butterfly and mix-proof common,

diaphram. Hygiene critical.Service – Butterfly, globe, gate, ball. High temperature, pressure.Flow control – Globe, modified globe and modified butterfly.Pressure reduction – Spring loaded pressure

reducing valve. Often for steam.Pressure relief – Spring or weight loaded.

Valves – Considerations

Duty – What the valve is designed to do (on/off, product routing, pressure reduction, etc.)

Process – Corrosion of valve body, seals

Temperature – Closed valve, solidifying product

Pressure – Max and min, do not overpressure

Capacity – Flow for given pressure

Leakrate – Maximum allowable leakage

Connections – Flanges, NPT, tubing, hose, etc.

Actuator – Torque, fail open or closed

Feedback – Signal indicating valve’s position

Valves in Breweries

Product Routing – Tight shut-off, CIP, material compatibility (elastomer seals). Butterfly and mixproof common.

Service Routing – Tight shut-off, high temperature and pressure. Globe, gate, ball.

Flow ControlWater temperature controlSteam flow rate control in wort boilingFermentation vessel temperature controltank gas top pressure controlCO2 addition during in-line carbonationwater addition during high gravity brewing

Readings for Next Week

BS+T – Chapter 1 (if you don’t read anything else, read this)

Singh – Chapter 2

Kunze – 10.5.1, 6.1.2, 6.1.3, 3.3.3, 3.3.4