“We Bring Engineering

to Life”

Biological and Agricultural Engineering

2015 Agent TrainingGrant EllingtonNov. 18, 2015

Topics• Energy cost update• Automatic ventilation controls• Heat recovery system evaluation• Modular tray steaming system• Farm Safety information

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

$11 / MMBTU @ $0.80/gal

$8.10 / MMBTU @ $0.65/therm

Natural Gas ($/therm)

LP Gas ($/gal)

No. 2 Fuel Oil ($/gal)

Wood Chips ($/ton)

       

0.20 0.18 0.28 280.30 0.27 0.42 420.40 0.37 0.56 560.50 0.46 0.70 700.60 0.55 0.83 840.70 0.64 0.97 980.80 0.73 1.11 1120.90 0.82 1.25 1261.00 0.92 1.39 1401.10 1.01 1.53 1541.20 1.10 1.67 1681.30 1.19 1.81 1821.40 1.28 1.95 1961.50 1.37 2.09 2101.60 1.46 2.22 2241.70 1.56 2.36 2381.80 1.65 2.50 2521.90 1.74 2.64 2662.00 1.83 2.78 2802.10 1.92 2.92 2942.20 2.01 3.06 308

Fuel Cost Comparison

* Heating System Efficiencies are assumed equal

2014

Automatic Ventilation Control – Improving Curing Management and Energy Efficiency

Most automatic systems measure relative humidity directly, but display dry-bulb and wet-bulb temperature.

2014 County Agent Survey Data(85,000 acres reported)

0

10

20

30

40

50

60

70

80

90

100

55

45

Wet-bulb Automatic Ventilation

% A

cres

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., Enercorp (Flue-Cured Tobacco

Services, LLC.), Rotem Control & Management Systems (Britt Technical Service)

Curing Issues?• Regardless if manual control or automation is utilized for curing,

system inputs are still determined by grower• Yellowing stage duration and at what temperature, what humidity,

when to begin advancing, etc., are mainly inputs based on growers experience curing

• However, there can be a combination of weather and agronomic factors that results in extreme difficulty producing the desired cured leaf quality

• Ideal curing schedules (dry-bulb and wet-bulb temperature profiles) are going to vary each season and within a given season

• Curing guidelines posted on the Growers Portal

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)

0 24 48 72 96 120 144 1680

10

20

30

40

50

60

70

80

90Barn 51 (Heat Recovery System) Barn 52

Time (hrs)

Dai

ly F

uel U

sage

(gal

s)Cure 9 Daily Fuel Usage Comparison

(55 gallons difference)

DeCloet DeCloet w/HRS *Long *Long w/HRS0

50

100

150

200

250

300

350

400

278

226

366

303

LPG

(gal

)

Exhaust Air Heat Recovery System Average Fuel Savings – 2014(DeCloet Barns – 10 Cures; Long Barns – 1 Cure)

* Last Cure Only

52 gals (20%) 63 gals (17%)

Long Long w/HRS DeCloet DeCloet w/HRS0

200

400

600

800

1000

1200

1400

1600

1800

1265

1109

1587

1321

Exhaust Air Heat Recovery System Results – 2015(Total Fuel Usage)

LPG

(gal

)

4 Cures 6 Cures

Long Long w/HRS DeCloet DeCloet w/HRS0

50

100

150

200

250

300

350

316

277265

220

LPG

(gal

)Exhaust Air Heat Recovery System Average Fuel Savings – 2015

(DeCloet Barns – 6 Cures; Long Barns – 4 Cures)

39 gals (12.3%) 45 gals (16.8%)

Exhaust Air Heat Recovery System Summary • Fuel savings averaged over the season for both barn makes was

approximately 15% per cure (ranged 30 to 58 gallons)• Curing time was not extended• Burner ON/OFF cycles reduced• Cured leaf was darker in the DeCloet barn with system• System cost is approximately $1800 installed• Simple payback at 15% savings is approximately 5 to 6 years (2015

prices, 8 cures per season)• Plan to continue in 2016

– add more barns with tube-axial fan configurations

Modular Tray Steaming System – 2014

System Specifications• Container dimensions: 6’ x 5’ x 10’ (300 ft3)• Approximately 450 trays• 176oF (80oC) for 30 min.• 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 – 210 to 215oF (saturated steam)

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 5.75 660

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

Time (hrs)

Tem

pera

ture

(oF)

10:00 am

Temperature Profiles vs. Time

176

176 oF (80 oC) for 30 min.

Steaming Trays 2016 & Beyond• Commercial units are probably going to be available in 2016• Growers can make their own system

– 176 oF (80 oC) for 30 minutes– Btu/hr requirement will scale with container volume (350 Btu/hr per

ft3 capacity)– Insulation not required– Only the largest operations will need 1000+ tray capacity– Must use steam not dry heat

Farm Safety Resources• Tobacco guide will include information on Ag machinery hazards• Information and links will be posted on Tobacco Growers Portal • Certified Safe Farm Program• http://www.nclabor.com/ash/ash.htm• National Ag Safety Database (NASD)• National Institute for Occupational Safety and Health (NIOSH)