Digester Design and Biogas Production Model
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Transcript of Digester Design and Biogas Production Model
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Purpose of Program
Producers investigating anaerobic digestion on their farm need to know how much biogas is produced, how muc
An interactive web-based model is under development by researchers at Cornell University that will allow a us
Project Participants
Kifle Gebremedhin, Curt Gooch, Peter Wright, and Binxin Wu.
Project Categories
Environmental Conditions `
Digester Type and Geometry
Installation of DigesterBuilding Materials
Soil Conditions
Manure Information
Computer Tips
The program will guide you from one page to the next. We suggest you follow through to the "Summary" page.
NOTE: It may be easier to first print the 6 category pages. Then, once you've been able to look up the d
INTRODUCTION
If you need to change a value on a previous page, use your browser's "back" button or the "previous" button at
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is needed to heat the digester, and how much is left over for other uses. The value for each is largely based on
r to determine the biogas generation and resulting energy partitioning for various digester conditions specified by
ata, you can come back to the site and enter all of the information at one time.
the bottom of the page. Once you make the change, be sure to hit "update" at the bottom of the page. Othe
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he design of the system and the availability of biologically degradable energy in the influent. Only after accurate
the user. Items in the program that the user can select include digester size, type, and construction materials, hy
rwise, the program will not use the updated value in its calculations.
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alues are predicted can a producer make an informed business decision relative to anaerobic digestion on their f
draulic retention time, operating temperature, influent value, geographic location, and others. The model will be s
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arm and the design that works best for their conditions.
et up so a user can manipulate values for many of the input variables to do "what ifs". Reports can be generated t
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hat will document each variable value for each iteration. A future component of the model will be a module that w
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ill perform a complete economic analysis based on the design chos
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Values
1A. Enter latitude (degrees)
1B. (ft)
1C. Maximum Minimum
Month Temp. Temp.
January
February
March
April
May
June
July
August
October
November
December
Calm Very clear 0.9
Clear 0.85
High wind 11-20 mph 0.8
Other 0.6
0
ENVIRONMENTAL CONDITIONS
Item
Enter elevation abovesea level
Enter maximum andminimum monthlytemperatures in
degrees F for the
desired month (s)
WindSpeed(selectnumberfromTable 1)
SkyConditions (selectnumberfromTable 2)
September
Table 1. WindSpeed Averages
Table 2. Coefficient for Sky Condition
20mph
Mostly
cloudy 0.7
Hazy orsmoggy
Cloudsobscurethe sun
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Item Values
2A. Plug flow
2B.
Mesophillic (101 F)
Other
2C. days
2D.
Length (L) (ft)
Width (W) (ft)
Depth (D) (ft)
Length (L) (ft)
Width (W) (ft)
Depth (D) (ft)
Radius (R) (ft)
DIGESTER TYPE AND GEOMETRY
Digestertype
(selectone)
Mixed (availablesoon)
Operatingtemperature (selectone)
Thermophillic (135F)
F
Enterhydraulicretentiontime
Digesterconfiguration (selectone)
Rectangular with flattop
Rectangular witharch top
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Radius (R) (ft)
Depth (D) (ft)
Depth (D1) (ft)
Depth (D2) (ft)
Radius (R) (ft)
2E. Top cover (in)
Wall (in)
Floor (in)
Wall insulation (in)
Floor insulation (in)
Upright cylindricalwith flat bottom
Cylindrical withconical bottom
Enterthickness
Top cover insulation
(in)
Sidewall insulation(in)
Endwall insulation
(in)
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Values
6A. Option 1.
(lb/day)
6B. Option 2.
Milk Fat
Milk Fat
MANURE INFORMATION
Two options are available for inputting manureinformation. Be sure to include only the manure that isprocessed by the digester.
Item
(ft3/day)
Enter daily volume ofmanure entering thedigester
Enter daily volatilesolids
Manure entering thedigester is calculatedfrom the followinginformation using
standard equations
Lactating Cows -Group 1
Number ofCows
MilkProduction
(lbs/cow/day)
Dry MatterIntake
(lbs/cow/day)
(g/gmilk/day)
Milk TrueProtein
(g/gmilk/day)
Lactating Cows -Group 2
Number ofCows
MilkProduction
(lbs/cow/day)
Dry MatterIntake
(lbs/cow/day)
(g/gmilk/day)
Milk TrueProtein
(g/gmilk/day)
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Milk Fat
Milk Fat
Milk Fat
Lactating Cows -Group 3
Number ofCows
MilkProduction
(lbs/cow/day)
Dry MatterIntake
(lbs/cow/day)
(g/gmilk/day)
Milk TrueProtein
(g/gmilk/day)
Lactating Cows -Group 4
Number of
CowsMilkProduction
(lbs/cow/day)
Dry MatterIntake
(lbs/cow/day)
(g/gmilk/day)
Milk TrueProtein
(g/gmilk/day)
Lactating Cows -Group 5
Number ofCows
MilkProduction
(lbs/cow/day)
Dry MatterIntake
(lbs/cow/day)
(g/gmilk/day)
Milk TrueProtein
(g/gmilk/day)
Lactating Cows -Group 6
Number ofCows
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Milk Fat
Dry Cows
Number of Dry Cows
(lbs)
Replacements
Organic Bedding for
(lbs/day)
Dry Cows (lbs/day)
Heifers (lbs/day)
Wastewater
Other Wastewater
MilkProduction
(lbs/cow/day)
Dry MatterIntake
(lbs/cow/day)
(g/gmilk/day)
Milk TrueProtein
(g/gmilk/day)
Average Body Weightof Dry Cows
Number of 1,000 to
1,250 lb heifersNumber of 800 to1,000 lb heifers
Number of 600 to 800lb heifers
Number of 400 to 600lb heifers
BeddingRequirements
Lactating
Cows
Milking CenterWastewater
(gallons/day)
(gallons/day)
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Values
4A.
Cover and Insulation
BUILDING MATERIALS
Item
Enter heat conductivity of building andinsulation materials from Table 3
Sidewall (BTU-in./hr-ft2-F)
Endwall (BTU-in./hr-ft2-F)
Floor (BTU-in./hr-ft2-F)
Cover (BTU-in./hr-ft2-F)
Sidewall insulation (BTU-in./hr-ft2-F)
Endwall insulation (BTU-in./hr-ft2-F)
Floor insulation (BTU-in./hr-ft2-F)
Top cover insulation (BTU-in./hr-ft2-F)
Table 3. Heat Conductivities of Building and Insulation Materials
Wall andFloor
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Material
13.87 1.03 1.65 0.95 0.73
Enter transmissivity of top cover material
GravelConcrete
Polystyrene BeadBoard
Polystyrene
CompositeBoard
Polystyrene -Expanded
(EPS)Polystyrene - Extruded
(XEPS)
Heatconductivit
y
(BTU-in./hr-ft2-
F)
4B. (Opaque = 0, Clear Glass or Plastic =1.0, White Plastic = 0.01-0.05)
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Values
5A.
Density
165.63 0.21 17.34
Granite 165 0.2 20.8
Quartz 166.25 0.19 61.03
Glass 169.38 0.2 5.55Clay 8.88
Gravel 14.33
Sand 16.45
21.78
14.7
6.24
Silt 8.62
Silt, stony 15.33
SOIL CONDITIONS
Item
Enter soil properties from Table4
Density (lb/ft3)
Specific heat(BTU/lb - F)
Heatconductivity(BTU-in./hr-ft2 -F)
Table 4. Thermal Properties of Soil Materials
Material SpecificHeat
HeatConductivity
(lb/ft3) (BTU/lb -F)
(BTU-in./hr-ft2 -F)
Soilminerals
Sand,saturated
Sand andgravel
Sand andclay
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Values3A.
INSTALLATION OFDIGESTER
ItemInstallationof digesterwithrespect tothesurface oftheground(selectone)
Underground(top wall isflush withtheground)
Partiallyunderground(Enterdepthbelow)
Aboveground(floor isflush withtheground)
Partialdepthunderground (ft
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Values
Environmental Conditions
Latitude (degrees) 43
Elevation (ft) 450
January 30 14 13 0.8
February 32 15 13 0.8
March 42 25 13 0.8
April 55 35 13 0.8
May 68 45 13 0.8
June 76 53 13 0.8
July 81 59 13 0.8
August 78 57 13 0.8
September 71 51 13 0.8
October 60 41 13 0.8
November 47 32 13 0.8
December 35 21 13 0.8
Digester Type and Geometry
Digester Type Plug flow
101
Hydraulic Retention Time (days) 22
Digester Configuration
Digester Dimensions
Length (ft) 104
Width (ft) 29
Depth (D1) (ft) 18
Depth (D2) (ft)
Radius (ft)
Thickness
Top Cover (in) 0.12
Wall (in) 11
Floor (in) 11
Top Cover Insulation (in) 0
Wall Insulation (in) 1.96
Floor Insulation (in) 1.96
Sidewall Insulation (in) 1.96
Endwall Insulation (in) 1.96
Installation of Digester
SUMMARY
Item
Max.
Temp. (F)
Min.Temp.
(F)
WindSpeed(mph)
SkyConditions
Operating Temperature (F)
Rectangular with flat
top
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Building Materials
Heat Conductivity of Building and Insulation Materials
10.4
10.4
10.4
2.29
1.04
1.04
1.04
0Transmissivity of Cover 0.01
Soil Conditions
Soil Properties
Specific Heat (BTU/lb - F)
Heat Conductivity (BTU/min-m - F)
Manure Information
2118
Daily volatile solids (lb/day) 0
Installation of Digester with Respect to the Surface ofthe Ground
Underground(top wall isflush withtheground)
Sidewall (BTU-in./hr-ft2-F)
Endwall (BTU-in./hr-ft2-F)
Floor (BTU-in./hr-ft2-F)
Cover (BTU-in./hr-ft2-F)
Sidewall Insulation (BTU-in./hr-ft2-F)
Endwall Insulation (BTU-in./hr-ft2-F)
Floor Insulation (BTU-in./hr-ft2-F)
Top Cover Insulation (BTU-in./hr-ft2
-F)
Density (lb/ft3) 90.52
0.19
6.93
Daily Volume of Manure Entering the Digester (ft3/day)
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Jan Feb Mar Apr May June July Aug Sep
OUTPUT
1. Heat Balance
Heat Gain(or Loss)(Btu)
Solar HeatGain 774808 1036486 1717663 2263017 2807262 2917542 2920118 2533927 1887244
HeatNeeded toHeatInfluent
19967424
318035092
919967424
319818783
416273816
512917599
911336816
012251075
314156273
9
Heat LossThroughTop cover 591955 524519 505794 406094 333463 264695 232305 251038 290075
Heat LossThroughWalls
83400860
75329809
83400860 64042035 59226698 52637289 51067918 52578803 54684295
Heat LossThroughFloor
52534878
47450857 52534878 39419578 40733564 39419578 40733564 40733564
39419578
Energy inEffluent(Manure +Gas)
24574790
122196584
624574790
123782054
924574790
123782054
924574790
124574790
123782054
9
HeatRequiredto OperatetheDigester
33542712
930261962
933439811
3
29979252
626022462
821858002
020248183
021354023
323406944
3
SupplementalEnergy
RequiredforDigesterHeating 0 0 0 0 0 0 0 0 0
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Jan Feb Mar Apr May June July Aug Sep
2. Gas Production
Biogas(ft3)
GrossBiogasProduction 2346217 2119163 2346217 2270532 2346217 2270532 2346217 2346217 2270532
BiogasNeeded toMaintainOperatingTemperature of theDigester 623470 562490 621557 557235 483688 406282 376360 396914 435073
NetBiogasAvailablefor OtherUse 1722746 1556673 1724659 1713297 1862528 1864250 1969856 1949302 1835459
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Oct Nov Dec Total
1328594 834686 668960 21690313
184680390
217652711
199674243
2049250415
378420 445974 547002 4771339
62852822 67258758
8340086078988101
2
40733564 39419578 5253487852566806
6
245747901
237820549
245747901
2893483355
287316603
323942336
335488025
3347880521
0 0 0 0
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Oct Nov Dec Total
2346217 2270532 2346217 27624813
534045 602123 623583 6222826
1812171 1668409 1722633 21401987