“We Bring Engineerin g to Life” Biological and Agricultural Engineering 2014 Agent Training Grant Ellington Nov. 19, 2014
Dec 22, 2015
“We Bring Engineering
to Life”
Biological and Agricultural Engineering
2014 Agent TrainingGrant EllingtonNov. 19, 2014
Topics• Energy outlook• Biomass system update• Automatic ventilation controls• New curing barn energy assessment – part II• Heat recovery system evaluation• Modular tray steaming system
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 20200
5
10
15
20
25Propane Natural Gas
2011
Dol
lars
per
Mill
ion
BT
U
Source: U.S. Energy Information Administration (LP Gas – Wholesale/Resale; N.G. – Commercial)
LP Gas and Natural Gas Price Outlook
$18 / MMBTU @ $1.30/gal
$9.40 / MMBTU @ $0.75/therm
Hurst Boiler Biomass Fired Hot Water Heating System; 2012 - 2014
Woodchip Biomass System and Automated Controls,
3.4 MMBtu/hr
Water to Air Heat Exchanger installed
in Return Air Plenum
Greenhouse Heating Applications w/Biomass Unit
Curing Barns and Greenhouse Applications
Result in Extending System Operation from July - March
Harnett Co.
Max Ox Smaller Capacity Biomass Heating System – 11 Barns and 200’ Greenhouse Application
(900,000 Btu/hr)
Person Co.
Performance Information Summary Hurst (2012) Max Ox (2013)
Boiler Capacity 3.4 million Btu/hr 1 million Btu/hr per unit
Number of Barns 17 11
Green Leaf Loading (lbs/barn) 18,000 13,000
Cured Leaf Weight per Cure (average, lbs/barn) 3,000 2,375
# of Cures 131 60
Total System Cost $300,000 -
Fuel Type Dry Wood Waste Green Chips
Season Total Fuel Usage (ton) 250 216
Fuel Cost ($/ton) $30 $25
Fuel Usage per Cure (ton) 1.9 3.6
Fuel Cost per Cure $66* $90
Fuel Cost per lb of Cured Leaf $0.02 $0.04
*Includes electricity cost for boiler.
Automated Biomass Fired System• Advantages
– Reduced fuel cost (70 to 90%)– Abundant renewable fuel– High combustion and thermal efficiency– Automated system (combustion controls, emissions, ash removal)– TSNA NOx mechanism eliminated
• Disadvantages– High initial investment– More equipment maintenance– Increased management – Limited or no local service technicians
Automatic Ventilation Control – Improving Curing Management and Energy Efficiency
Most automatic systems measure relative humidity directly, but display dry-bulb and wet-bulb temperature.
2013 County Agent Survey Data(86,000 acres reported)
0
10
20
30
40
50
60
70
80
90
100
48.1
40.8
Wet-bulb Automatic Ventilation
% Acres
Real-time Continuous Monitoring of the Curing Environment• Significant time management tool for growers• Web-based access to monitoring system• Audible alarm conditions to help minimize leaf damage during
equipment failures or power loss• Data logging capabilities• Suretrol or Cureco, Marco Mfg., and Enercorp (Flue-Cured Tobacco
Services, LLC.)
New Curing Barn Performance Evaluation
Background• Energy usage remains a significant input cost • Considerable price fluctuations of petroleum fuels in recent years and
continued uncertainty of future prices• More growers continue to make energy efficiency improvements to
existing infrastructure and replacing older barns • Approximately 15,000 to 18,000 operational barns in NC • 6 manufacturers made barns for the 2014 season• Energy efficiency and energy conservation is the best source of new
energy and is a cost-effective solution• Research continues to explore energy efficiency improvements and
renewable energy technologies that are economically feasible
Primary Objectives • New curing barn assessment to provide on-farm independent energy
and other performance related information to assist growers with curing infrastructure decisions– Total energy footprint (LP gas and kWh usage)– Green and cured leaf weights – Cure duration– Static pressure (airflow)– Cured leaf quality, barn curing management (user-friendly)
• Exhaust air heat recovery system evaluation
New Barn Specifications• Long (10-box)
– Long HEx @ 350,000 Btu/hr
• World Tobacco (15-box)– Evans HEx @ 500,000+ Btu/hr – 2” insulated panels
• Tytun (14-box, 32T)– Powermatic HEx @ 400,000 Btu/hr – 4” insulated panels
• Taylor (10-box)– Evans HEx @ 390,000 Btu/hr – 3” insulated panels
• All fan motors 1-phase, 10 Hp, except Tytun 18-box and Long Prototype (15 Hp) • All barn pads insulated • Suretrol controllers on all barns
• Long Prototype (10-box)– Long HEx @ 400,000 Btu/hr
• World Tobacco Basic (12-box)– Evans HEx @ 325,000 Btu/hr – 2” insulated panels
• Tytun (18-box, 32T)– Powermatic HEx @ 550,000 Btu/hr
Heat Exchanger and Burner Operating Efficiently– set the burner firing rate correctly (325,000 to 425,000 BTU/hr typical range)– burner and all controls properly adjusted
Box ComparisonLong, Taylor Tytun (32T) World Tobacco,
DeCloet
Tytun - 18 Tytun - 14 Long - Prototype
Taylor - 10 Long - 10 World - 15 Existing Long
Existing DeCloet
World - 120
50,000
100,000
150,000
200,000
250,000
300,000
350,000
Lbs G
reen
Lea
f
Total Green Weight – 10 Cures
Tytun - 18 Tytun - 14 Long - Prototype
Taylor - 10 Long - 10 World - 15 Existing Long
Existing DeCloet
World - 120
10,000
20,000
30,000
40,000
50,000
60,000
70,000
Lbs C
ured
Lea
f
Total Cured Weight – 10 Cures
Existi
ng Long
World
- 15
Long
- 10
Tytu
n - 18
Existi
ng DeCloet
Long -
Proto
type
Tytu
n - 14
Taylor -
10
World
- 12
0
1
2
3
4
5
6
7
8
9
10
Days
Season Average Cure Duration(10 Cures)
Long - Proto-type
Tytun - 18 Long - 10 Existing Long World - 15 Taylor - 10 Tytun - 14 Existing DeCloet
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
2,000
kWh
Season Average Electrical Energy Usage
15 Hp10 Hp
7.5 Hp
Taylor - 10 World - 12 Tytun - 18 Long - Prototype
Tytun - 14 Long - 10 Existing DeCloet
World - 15 Existing Long
0
2
4
6
8
10
12
14
16
18
20Mid and Upper-Stalk Cures Only All Cures
lbs
Cure
d Le
af /
gal
LPG
*
* No lower-stalk cures
2.3 ¢ / lb14.5
11.5
2014 Season Average Curing Efficiency Comparisons
Fuel Efficiency(lbs/gal)
Fuel Cost ($/unit)
0.80 1.00 1.20 1.40 1.60 1.80 2.00
$ / lb Cured
7 0.114 0.143 0.171 0.200 0.229 0.257 0.286
8 0.100 0.125 0.150 0.175 0.200 0.225 0.250
9 0.089 0.111 0.133 0.156 0.178 0.200 0.222
10 0.080 0.100 0.120 0.140 0.160 0.180 0.200
11 0.073 0.091 0.109 0.127 0.145 0.164 0.182
12 0.067 0.083 0.100 0.117 0.133 0.150 0.167
13 0.062 0.077 0.092 0.108 0.123 0.138 0.154
15 0.053 0.067 0.080 0.093 0.107 0.120 0.133
17 0.047 0.059 0.071 0.082 0.094 0.106 0.118
Energy Efficiency and Estimated Cost per Pound Cured Leaf (fuel only)
Summary• Approximately 25% increase in fuel efficiency averaged over the season• 6 barn manufacturers made and sold barns in 2014• Energy performance alone is not the single justification for purchasing a
given barn make, but remains an important factor– New barn costs– Material handling capacity– Existing barn infrastructure– Existing material handling system– Serviceability and maintenance costs
• Independent performance information can help manufacturers with developing and implementing technologies to improve overall barn design
• Demand for used all metal barns ?? • Plan to continue work in 2015
Exhaust Air Heat Recovery System Evaluation
FAN
Heat Exchanger
Tobacco Curing BoxesTobacco
Heated Air
IntakeAir
Exhaust Air
Heat Exchanger (recovery coil)
Heat Recovery System Schematic Heat Exchanger (preheat coil)
Exhaust Vent Heat Exchanger(recovery coil)
Intake Vent Heat Exchanger
(preheat coil)
Single Cure Evaluated Diff. = 63 gals (17%)
0 24 48 72 96 120 144 168 192 2160
10
20
30
40
50
60
70
80Barn 51 (Heat Recovery System) Barn 52
Time (hrs)
Dai
ly F
uel U
sage
(gal
s)
Cure 7 Daily Fuel Usage Comparison (60 gallons difference)
DeCloet DeCloet w/HRS *Long *Long w/HRS0
50
100
150
200
250
300
350
400
278
226
366
303
LPG
(gal
s)
Exhaust Air Heat Recovery System Average Fuel Savings – 2014
* Last Cure Only
Modular Tray Steaming System
System Specifications• Container dimensions; 6’ x 5’ x 10’• Approximately 450 trays• Steam generator with fuel oil burner
– 0.6 gpm @ 150 psi = 100,000 Btu/hr (420,000 Btu/hr max)– 8 to 9 gph water input – T = 210 to 215oF (steam)
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200Front Door Floor Air Temp. 2nd Tray from bottom 2nd Tray from Top Series7 Series9 Series11
Time
Tem
pera
ture
(oF)
Temperature Profiles vs. Time