Combustion Air Pre- heater ME 486 4/25/03 Combustion Air Pre-heater ME 486 4/25/03 Final Design...
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Transcript of Combustion Air Pre- heater ME 486 4/25/03 Combustion Air Pre-heater ME 486 4/25/03 Final Design...
Combustion Air Pre-Combustion Air Pre-heaterheater
ME 486ME 486
4/25/034/25/03
Combustion Air Pre-heater
ME 486ME 486
4/25/034/25/03
Final Design Presentation
Photo courtesy of David Pedersen
224/25/034/25/03 Carl VanceCarl Vance
Purina Boiler Efficiency TeamPurina Boiler Efficiency Team
Members and RolesMembers and Roles Ryan CookRyan Cook
Documenter and SecretaryDocumenter and Secretary
Kofi CobbinahKofi CobbinahTeam Leader and Website ManagerTeam Leader and Website Manager
Carl VanceCarl Vance
Communicator and HistorianCommunicator and Historian
Matt BishopMatt BishopFinancial Officer and MediatorFinancial Officer and Mediator
334/25/034/25/03 Carl VanceCarl Vance
Our Client – NestléOur Client – Nestlé Purina Purina
Client Contact:Client Contact: John Cain John Cain
Manager of Engineering at the Flagstaff Manager of Engineering at the Flagstaff Plant. Plant.
NAU Graduate in Mechanical EngineeringNAU Graduate in Mechanical Engineering
Purina as a company:Purina as a company:Flagstaff Plant opened in 1975Flagstaff Plant opened in 1975
Employs 180 peopleEmploys 180 people
Purina is now a division of Nestlé FoodsPurina is now a division of Nestlé Foods
444/25/034/25/03 Carl VanceCarl Vance
Project DescriptionProject Description
Problem DefinitionProblem Definition NestlNestlé Purina has requested a design for a é Purina has requested a design for a
combustion air pre-heater. The goal of the combustion air pre-heater. The goal of the project is to provide savings for the plant by project is to provide savings for the plant by reducing energy costs and improving reducing energy costs and improving efficiency in the steam system.efficiency in the steam system.
554/25/034/25/03 Carl VanceCarl Vance
Our Design PhilosophyOur Design Philosophy
Finish Design On Time and Under Budget.Finish Design On Time and Under Budget.
Satisfy the Client’s Requirements.Satisfy the Client’s Requirements.
Design for Safety.Design for Safety.
Act with Integrity.Act with Integrity.
664/25/034/25/03 Carl VanceCarl Vance
Client’s RequirementsClient’s Requirements
Client’s Needs Statement:Client’s Needs Statement:
Design of a combustion air preheater must Design of a combustion air preheater must be:be: Economically FeasibleEconomically Feasible Minimize Modifications to Existing SystemsMinimize Modifications to Existing Systems Show an improvement in evaporation rate.Show an improvement in evaporation rate.
774/25/034/25/03 Carl VanceCarl Vance
Purina Steam SystemPurina Steam System
The boiler produces approximately 500,000 The boiler produces approximately 500,000 lbm of steam per day. lbm of steam per day.
40%: cooking products.40%: cooking products.
50%: drying products.50%: drying products.
10%: miscellaneous areas: air and water 10%: miscellaneous areas: air and water heating systems.heating systems.
Steam production is 2/3 of the plant's total Steam production is 2/3 of the plant's total energy use.energy use.
884/25/034/25/03 Carl VanceCarl Vance
Basic Basic Boiler OperationBoiler Operation
Source: Source: Reducing Energy CostsReducing Energy Costs, KEH Energy Engineering, 1990., KEH Energy Engineering, 1990.
994/25/034/25/03 Carl VanceCarl Vance
What is a Combustion Air What is a Combustion Air PreheaterPreheater
Device or system that heats the boiler Device or system that heats the boiler intake air before it enters the combustion intake air before it enters the combustion chamber.chamber.
Uses recaptured waste heat that would Uses recaptured waste heat that would normally leave the boiler to the normally leave the boiler to the atmosphere. atmosphere.
10104/25/034/25/03 Carl VanceCarl Vance
Source: Source: Reducing Energy CostsReducing Energy Costs, KEH Energy Engineering, 1990., KEH Energy Engineering, 1990.
11114/25/034/25/03 Carl VanceCarl Vance
Design OptionsDesign Options
What are the industry standards?What are the industry standards?
Which design best meets our client’s Which design best meets our client’s requirements.requirements.
12124/25/034/25/03 Carl VanceCarl Vance
Runaround SystemRunaround System
Source: Source: Canadian Agriculture Library, http://www.agr.gc.ca/cal/calweb_e.htmlCanadian Agriculture Library, http://www.agr.gc.ca/cal/calweb_e.html
13134/25/034/25/03 Carl VanceCarl Vance
Gas - to - Gas Plate Heat Gas - to - Gas Plate Heat ExchangerExchanger
Source: Source: Canadian Agriculture Library, Canadian Agriculture Library, http://www.agr.gc.ca/cal/calweb_e.htmlhttp://www.agr.gc.ca/cal/calweb_e.html
14144/25/034/25/03 Ryan CookRyan Cook
Concentric Duct DesignConcentric Duct Design
Source: Canadian Agriculture Library, http://www.agr.gc.ca/cal/calweb_e.html
15154/25/034/25/03 Ryan CookRyan Cook
Design ChoiceDesign Choice
Final Design Choice: Final Design Choice: Concentric Duct DesignConcentric Duct Design
Air enters into a duct that surrounds the Air enters into a duct that surrounds the stack.stack.
The stack transfers heat to the air by The stack transfers heat to the air by convection and radiation.convection and radiation.
The air enters into the boiler at a higher The air enters into the boiler at a higher temperature.temperature.
16164/25/034/25/03 Ryan CookRyan Cook
Why a Concentric Duct?Why a Concentric Duct?
InexpensiveInexpensiveNo modifications to current systemNo modifications to current systemSimple Design that WorksSimple Design that WorksPassive SystemPassive System
17174/25/034/25/03 Ryan CookRyan Cook
Design BenefitsDesign Benefits
Concentric Duct Design Will Provide:Concentric Duct Design Will Provide: Relatively Low Installation CostRelatively Low Installation Cost Low Material CostsLow Material Costs Low Impact on Existing SystemsLow Impact on Existing Systems High Payback on InvestmentHigh Payback on Investment Low Maintenance CostsLow Maintenance Costs
18184/25/034/25/03 Ryan CookRyan Cook
Preheater Design BasicsPreheater Design Basics
19194/25/034/25/03 Ryan CookRyan Cook
Given ConditionsGiven Conditions
Exhaust Stack Surface TemperatureExhaust Stack Surface Temperature 399 K = 258 degrees Fahrenheit399 K = 258 degrees Fahrenheit
Inlet Air TemperatureInlet Air Temperature 305 K = 89 degrees Fahrenheit305 K = 89 degrees Fahrenheit
Exhaust Stack HeightExhaust Stack Height 4.3 meters4.3 meters
Exhaust Stack DiameterExhaust Stack Diameter 3 feet = 0.9144 meters3 feet = 0.9144 meters
20204/25/034/25/03 Ryan CookRyan Cook
Specifications to dateSpecifications to date
The exhaust stack height is 4.3 meters, The exhaust stack height is 4.3 meters, which fixes our duct height and will provide which fixes our duct height and will provide the surface area for heat transfer.the surface area for heat transfer.
Duct diameter will be 1.05 meters to Duct diameter will be 1.05 meters to optimize forced convection.optimize forced convection.
Mass flow rate of air through duct will be Mass flow rate of air through duct will be 4.52 kg/s. This gives an air velocity of 4.52 kg/s. This gives an air velocity of 13.56 m/s.13.56 m/s.
21214/25/034/25/03 Ryan CookRyan Cook
Temperature DistributionTemperature Distribution
22224/25/034/25/03 Ryan CookRyan Cook
Our DesignOur Design
23234/25/034/25/03 Ryan CookRyan Cook
Our DesignOur Design
24244/25/034/25/03 Ryan CookRyan Cook
InstallationInstallation
Two half tubes that will be welded together Two half tubes that will be welded together around the stack.around the stack.
Spacers will be inserted along the bottom Spacers will be inserted along the bottom to to keep the duct steady.to to keep the duct steady.
Will be hung by threaded rod supports Will be hung by threaded rod supports from the ceiling.from the ceiling.
Mathematical ModelsMathematical Models
Convection ModelConvection Model
Heat Exchanger ModelHeat Exchanger Model
Drag ModelDrag Model
Radiation ModelRadiation Model
Insulation ModelInsulation Model
Known Values for ConvectionKnown Values for Convection
Volumetric Flow Rate = 2.84 mVolumetric Flow Rate = 2.84 m33/s/s
Thermal Conductivity = .0263 W/(m*K)Thermal Conductivity = .0263 W/(m*K)
Kinematic Viscosity = 1.59E –05 mKinematic Viscosity = 1.59E –05 m22/s/s
Prandlt Number = 0.707Prandlt Number = 0.707
TTs s – T– Taa = 100 K = 100 K
Stack Surface Area = 12.26 mStack Surface Area = 12.26 m22
Stack Diameter = 0.9144 mStack Diameter = 0.9144 m
Convection ModelConvection Model
variable
O.D. (D2) I.D. (D1) hydraulic diameter X section area (m^2) airspeed (m/s) Re1 0.9144 0.086 0.13 22.04 59300
1.05 0.136 0.21 13.56 578001.1 0.186 0.29 9.66 56400
1.15 0.236 0.38 7.43 550001.2 0.286 0.47 5.98 53700
Convection ModelConvection Model
Pr Nu h (W/(m^2 K)) Ts - Ta (K) q" stack S.A (m^2) Energy transfer (W)0.707 131.8 40.49 100 4050 12.26 49700
129.1 25.04 2500 30700126.6 17.94 1790 21900124.1 13.85 1390 17000121.8 11.22 1120 13700
Convection Model SavingsConvection Model Savings
Estimate
Btu/h Yearly Btu Savings Gallons per year saved Yearly monetary savings 5- year savings 169600 1.038E+09 6920 $3,180 $15,900104800 6.410E+08 4270 $1,960 $9,80074700 4.570E+08 3050 $1,400 $7,00058000 3.550E+08 2370 $1,090 $5,45046700 2.860E+08 1910 $880 $4,400
Known Values for Known Values for Heat Exchanger Heat Exchanger
Cp,c = 1007 (J/kg*K) Cp,c = 1007 (J/kg*K)
Cp,h = 1030 (J/kg*K)Cp,h = 1030 (J/kg*K)
hhi i = 17.31 (W/m = 17.31 (W/m22*K)*K)
hhoo = 25.05 (W/m= 25.05 (W/m22*K)*K)
TTc,Ic,I = 305.4 (K) = 305.4 (K)
TTh,Ih,I = 509.1 (K) = 509.1 (K)
Mass Flow Rate = 4.52 kg/sMass Flow Rate = 4.52 kg/s
Heat Exchanger ModelHeat Exchanger Model
variableTh,o (K) Th,I (K) mdot h (kg/s) mdot c (kg/s) q (Watts)503.72 509.10 4.52 4.52 25050503.73 25000503.74 24950503.75 24910503.76 24860503.77 24810503.78 24770
Heat Exchanger ModelHeat Exchanger Model
result checkTc,I (K) Tc,o (K) Delta Tlm (K) U (W/m^2*K) Area (heat transfer)305.40 310.90 198.26 10.24 12.34
310.89 198.27 12.32310.88 198.28 12.29310.87 198.29 12.27310.86 198.30 12.25310.85 198.31 12.22310.84 198.32 12.20
Heat Exchanger SavingsHeat Exchanger Savings
Btu/h Yearly Btu Savings Gallons per year saved Yearly monetary savings 5- year savings85500 5.23E+08 3490 $1,610 $8,05085300 5.22E+08 3480 $1,600 $8,00085100 5.21E+08 3470 $1,600 $8,00085000 5.20E+08 3470 $1,600 $8,00084800 5.19E+08 3460 $1,590 $7,95084700 5.18E+08 3450 $1,590 $7,95084500 5.17E+08 3450 $1,590 $7,950
Known Values for Drag ModelKnown Values for Drag Model
Mass Flow Rate Mass Flow Rate
““a” = O.D. / 2a” = O.D. / 2
““b” = I.D. / 2b” = I.D. / 2
Drag ModelDrag Model
a (O.D./2) b (I.D./2) f duct friction head loss h f
0.5 0.4572 1.500 1.619E-03 2.0000.525 0.4572 1.500 1.660E-03 0.4900.55 0.4572 1.499 1.701E-03 0.1860.575 0.4572 1.499 1.744E-03 0.089
0.6 0.4572 1.498 1.786E-03 0.049
Drag ModelDrag Model
Sum of K values minor losses hm
0.25 6.1910.3 2.812
0.31 1.4750.35 0.9840.37 0.675
Drag Model CostsDrag Model Costs
specific energy loss (J/kg) power loss (W) kWh per year cost per year 5 year cost 80.3 363 2220 $133.2 $66632.4 146 890 $53.4 $26716.3 74 450 $27.0 $13510.5 47 290 $17.4 $877.1 32 200 $12.0 $60
Known Values for Radiation Known Values for Radiation
Inner and Outer DiametersInner and Outer Diameters
Emissivity of Steel Stack, εEmissivity of Steel Stack, ε1 1 = 0.87 = 0.87
Emissivity of Aluminum Duct, εEmissivity of Aluminum Duct, ε2 2 = 0.15= 0.15
Stack Surface AreaStack Surface AreaStefan- Boltzmann Constant Stefan- Boltzmann Constant σ = 5.67E –08 (W/(m2*Kσ = 5.67E –08 (W/(m2*K44))))Stack Temperature = 399.7 KStack Temperature = 399.7 KDuct Temperature = 322 KDuct Temperature = 322 K
Radiation ModelRadiation Model
variable
O.D. I.D. ε1 ε2 σ (W/(m2*K4)) stack surface area (m^2) T1 T2
1 0.9144 0.87 0.15 5.67E-08 12.26 399.7 3221.051.1
1.15
Radiation Model SavingsRadiation Model Savings
q (W) Btu/h Yearly Btu Savings Gallons per year saved Yearly monetary savings 5- year savings1620 5530 3.38E+07 225 $104 $5201690 5770 3.53E+07 235 $108 $5401750 5970 3.65E+07 243 $112 $5601820 6210 3.80E+07 253 $116 $580
Known Values for InsulationKnown Values for Insulation(Modeled as Fiberglass)(Modeled as Fiberglass)
R – Values:R – Values: Preheated Air = 0.559 (mPreheated Air = 0.559 (m2*2*K)/WK)/W Duct = 4.9E –04 (mDuct = 4.9E –04 (m2*2*K)/WK)/W Fiberglass Insulation = 16.78 (mFiberglass Insulation = 16.78 (m2*2*K)/W K)/W
(per inch)(per inch)
Average Temperature DifferenceAverage Temperature Difference
Insulation ModelInsulation Model
insulation thickness (inches) preheated air duct insulation0 R value 0.559 0.00041 0.001 0.559 0.00041 9.272 0.559 0.00041 18.534 0.559 0.00041 37.066 0.559 0.00041 55.59
Insulation Model CostsInsulation Model Costs
q (watts) Btu/h yearly cost 5 year cost5.36 18.30 $0.34 $1.720.31 1.04 $0.02 $0.100.16 0.54 $0.01 $0.050.08 0.27 $0.01 $0.030.05 0.18 $0.00 $0.02
insulation thickness (inches)01246
44444/25/034/25/03 Kofi CobbinahKofi Cobbinah
5 Year Savings Summary5 Year Savings Summary
Force ConvectionForce Convection $7980.00$7980.00
RadiationRadiation $540.00$540.00
Drag LossDrag Loss - $270.00- $270.00
Insulation LossInsulation Loss - $2.00- $2.00
Total Total $8250.00$8250.00
45454/25/034/25/03 Kofi CobbinahKofi Cobbinah
Design EstimateDesign Estimate
Total implementation cost:Total implementation cost:
Materials--- $350Materials--- $350
Labor--- $1650 Labor--- $1650
Total of approximately: $2,000Total of approximately: $2,000Source: McGuire Construction Co.Source: McGuire Construction Co.
46464/25/034/25/03 Kofi CobbinahKofi Cobbinah
Energy SavingsEnergy Savings
The energy added to the system was The energy added to the system was converted to kBtu’s per hour.converted to kBtu’s per hour.
Total kBtu’s per year saved = 553,000Total kBtu’s per year saved = 553,000
The evaporation rate will improve 1% for The evaporation rate will improve 1% for a daily average.a daily average.
47474/25/034/25/03 Kofi CobbinahKofi Cobbinah
Financial SavingsFinancial Savings
The Financial Savings were based on fuel The Financial Savings were based on fuel oil at $0.46 per gallon and 150 kBtu/gallon.oil at $0.46 per gallon and 150 kBtu/gallon.
This provides a 5 year savings of $8,248.This provides a 5 year savings of $8,248.
Simple payback for the project is 1.3 Simple payback for the project is 1.3 years.years.
48484/25/034/25/03 Kofi CobbinahKofi Cobbinah
Expenses Expenses
Total Expenses: $150.00Total Expenses: $150.00
Printing/Binding ---$100.00Printing/Binding ---$100.00
Photocopying --- $50.00Photocopying --- $50.00
49494/25/034/25/03 Kofi CobbinahKofi Cobbinah
Time LogTime Log
Average individual Hours: 120.7Average individual Hours: 120.7
Total Team Hours: 482.8Total Team Hours: 482.8
50504/25/034/25/03 Kofi CobbinahKofi Cobbinah
Our Appreciation Goes To:Our Appreciation Goes To:
Nestle Purina Company at Flagstaff.Nestle Purina Company at Flagstaff.
Mr. John Cain – Client Contact.Mr. John Cain – Client Contact.
Dr Peter Vadasz – Advisor.Dr Peter Vadasz – Advisor.
Dr. David Hartman – ME 486 Professor.Dr. David Hartman – ME 486 Professor.
Everyone at our presentation today.Everyone at our presentation today.
51514/25/034/25/03 Kofi CobbinahKofi Cobbinah
Project WebsiteProject Website
http://www.cet.nau.edu/Academic/Design/http://www.cet.nau.edu/Academic/Design/D4P/EGR486/ME/02-Projects/Heat/index.D4P/EGR486/ME/02-Projects/Heat/index.htmhtm
Or go to Or go to www.cet.nau.eduwww.cet.nau.edu and click on and click on “Design 4 Practice” and follow links to “Design 4 Practice” and follow links to “Senior Project Websites” and click on our “Senior Project Websites” and click on our websitewebsite
52524/25/034/25/03 Kofi CobbinahKofi Cobbinah
ConclusionConclusion
The team has been able to prove that The team has been able to prove that adequate heat transfer is available to pay adequate heat transfer is available to pay for the design, reduce energy costs, and for the design, reduce energy costs, and improve the efficiency of the boiler.improve the efficiency of the boiler.
Questions?
Photo courtesy of David Pedersen