Closed Loop Fumigation of a Concrete Elevator

Broken Arrow, Oklahoma

Dr. Carol JonesDepartment of Biosystems and Agricultural Engineering

Oklahoma State University

Edmond Bonjour and Randy BeebyStored Products Research and Education CenterDepartment of Entomology and Plant Pathology

Oklahoma State University

Mark Fultz, ManagerHansen Mueller Grain Co., Broken Arrow, Oklahoma

Urbanization around Rural Elevator

Challenges

• Fumigation safety is a concern to neighbors and to employees

• Conventional methods of phosphine fumigation put workers and people in close proximity in danger

• Improper fumigation leads to insect resistance

Goals of this Project

• Seek a method to improve safety of fumigating with phosphine

• Seek a method to decrease the amount of fumigant required

• Seek a method to increase the concentration distribution throughout the grain bins

Common Fumigation Methods and Negative

Effects• Probe and Tarp: exposure during tarping• Automatic Dispenser: pellets spill from buckets and

release gas in unwanted areas, shrinkage caused from turning and moving grain

• Gravity Fumigation: little control of where gas may go

Each method offers increased risk of exposure during insertion of fumigant into the grain.

Proposed Method

• Closed Loop Fumigation System in a concrete silo• Example of a J-System patented by James Cook in

1980.• Consists of:

– Sealing air leaks in storage structure– Installing low pressure low volume centrifugal blower re-

circulating air-gas mixture from headspace of grain into base of silo

– Installing pipes from fan to blower and back into silos

Closed Loop Basic IdeaPressured base ducts force gas mixture upward

through grain bulk providing better gas distribution through grain.

Grain Bulk

Headspace

Blower

Bin Diagram of Elevator Facility

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Closed loop system installed in one half of the elevator while the other half remained unchanged for a conventional method fumigant application

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CLF Conventional

8660 MT capacity

(120,000 bu)

Dosage: Phosphine Pellets

• Manager chose his normal dosage rate of 500 pellets/1000 ft3 which is his normal dosage rate. Both sides of the elevator were treated the same. – CLF side: pellets distributed on top of the grain.– Conventional side: pellets were inserted into the grain as it

was loaded into the bin

Monitoring

• Monitoring fumigation: top, bottom, and middle of bin

Monitoring

• Electronic gas meters were used to measure phosphine concentration every 4 hours for the first 32 hours and every 10 hours for the next 88 hours.

ResultsCLF versus Conventional Fumigation

0

500

1000

1500

2000

2500

0 10 20 30 40 50 60 70 80

Hour from Treatment

pp

m

CLF BIN

CONVENTIONAL BIN

200 PPM

A closed loop system was installed in one half of the elevator while the other half remained unchanged for a conventional method fumigant application

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CLF Conventional

8660 MT capacity

(120,000 bu)

Installation of CLFBin Diagram of Elevator Facility

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Seal Inner Vents

Installation of CLF• Seal silos as completely as possible…inner vents to

silos not included in loop

Installation of CLFBin Diagram of Elevator Facility

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Seal Outer Vents

Installation of CLF• Seal silos as completely as possible…outer

vents

Installation of CLF• Seal silos as completely as possible...access

openings

Proposed Method for StudyBin Diagram of Elevator Facility

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Install Fan on top of Bin 6 (outside of head house)

Headhouse

Proposed Method for Study

• Blower mounted outside on top of one bin adjacent to the head house.

• 1/3 HP supplying 320 cfm

Proposed Method for Study

• Installing pipes from fan to blower and back into silos

Flexible hose from fan through window to man lift shaft

Down man lift shaft to ground level using 3 inch PVC sewage pipe

Proposed Method for Study

• Installing pipes from fan to blower and back into silos

After Fumigation

• Blower discharge piping was disconnected and the blower was used to evacuate the fumigant from the CLF system and bins.

• Evacuation can be accomplished when the danger to workers or to residents around the elevator is the least.

• Gas can be discharged 120 ft. above ground level reducing danger

• Closed Loop Fumigation– Installation costs– Less fumigant– Less labor– Less worker exposure and

health costs

• Conventional Fumigation– Turning costs and product

shrinkage– More fumigant– More labor– More bin entry required of

workers causing health risk and higher insurance rates

Economic Comparison ($4/bu wheat)

Economic Comparison ($8/bu wheat)

Conclusion• Closed loop fumigation was more successful

since it reached the desired 200 ppm for 100 hours. Conventional fumigation did not reach this level.

• ¾ of the fumigant could have been saved in this elevator

• Closed loop fumigation is ultimately cheaper• Closed loop fumigation is safer than conventional

fumigation when carried out properly

Closed Loop Fumigation of a Concrete Elevator

Broken Arrow, Oklahoma

Dr. Carol JonesDepartment of Biosystems and Agricultural Engineering

Oklahoma State University

Edmond Bonjour and Randy BeebyStored Products Research and Education CenterDepartment of Entomology and Plant Pathology

Oklahoma State University

Mark Fultz, ManagerHansen MuellerGrain Co., Broken Arrow, Oklahoma