[Gasification] Corn Cob Gasifiers

Mon Feb 23 12:14:50 CST 2015

Crop residues, like corn stalks and cobs,  are also used to prevent wind
erosion:   http://www.ext.colostate.edu/pubs/crops/00518.html 

In many of the US corn growing regions, removing more of the cover requires
that you re-invest in some other type of soil stabilization. That's another
cost for the farmer/ land holder to consider when making the decision to
harvest residues vs. leave them on the field.

kind regards,

Erin Rasmussen

erin at trmiles.com

From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] On
Behalf Of Tom Miles
Sent: Monday, February 23, 2015 8:41 AM
To: mark at ludlow.com; 'Discussion of biomass pyrolysis and gasification'
Subject: Re: [Gasification] Corn Cob Gasifiers

Mark,

There is a lot of equipment out there for collecting or separating cobs that
is used commercially.  Wagons that you pull behind the combine, , screens,
etc.  Poet and others have literally spent millions over several seasons
testing different methods of bringing in cobs for conversion. I know some of
the commercial contractors who have done the work. There are people who have
been harvesting residues for many years. they all come back shaking their
heads saying that cob yields per acre are too low to make large scale
collection feasible. At a smaller farm level it is practical but there you
are never including the true cost of collection.   

>From "Cob Products: Physical Properties, Chemical Properties and Uses of
Anderson's Corncob Products" second edition. 1978. The Anderson's Cob
Products Division, Maumee, Ohio.  http://www.andersonscob.com/

"CAVITY FILLER FOR CADAVERS: Grit-O'Cobs granules have been employed as a
cavity filler for cadavers. The purpose of the cavity filler is to replace
the space occupied by organs that may have been removed or flattened by a
medical examination or autopsy so that the body is presentable for viewing
in a casket. Grit-O'Cobs grades 1420 and 1014 are used for this purpose."
(p.288)

http://www.andersonscob.com/product-list/

In 1979 we designed a cob and  stover burner to generate heat for drying
grain. We designed it in 1979 for Wes Buchele and Paul Claar in the Ag
Engineering department at Iowa State University. There were so many theses
written using it on campus that we called it a thesis generator instead of a
gas generator. After we showed them how to build and operate one ISU
modified the design, adding a heat exchanger.  One masters student made a
commercial version at his family ag equipment company. They built about 20
of them until propane prices receded. It was a combined pile and suspension
burner that we called the "concentric vortex." 

There was a lot of work on cob and crop residue gasification at that time.
Much of the literature is in books and papers that are accessible, usually
at a cost, online. Most of the principal investigators and inventors have
retired, died, or have gone into other fields.  

Crop residues, including cobs, tend to get used when energy or fiber prices
are high and are abandoned when prices drop. In those days we projected that
cobs and stover would be used when propane got to $3/MMBtu or about
$0.22/gal. We figured we could bring in cobs and own and operate the burner
at a total cost of about $48/ odt. Cob collection with stover was about
$25/ton at the time. Today with propane at $0.90/gal ($12.50/MMBtu) the
equivalent cost of energy from cobs is about $155/ odt. Collection costs are
about $60/odt. But propane is pretty convenient.    

Cobs should burn well in a TLUD. Has anyone built a large one to burn cobs? 

Tom

From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] On
Behalf Of Mark Elliott Ludlow
Sent: Sunday, February 22, 2015 10:54 PM
To: 'Discussion of biomass pyrolysis and gasification'
Subject: Re: [Gasification] Corn Cob Gasifiers

Tom,

Why isn't "source sorting" feasible, given that a shortage of cadavers may
justify modifications to corn pickers? Was the spreading of cobs a benign
impulse or done for lack of anything better or more creative to do?

Mark

From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] On
Behalf Of Tom Miles
Sent: Saturday, February 21, 2015 9:18 PM
To: 'Discussion of biomass pyrolysis and gasification'
Subject: [Gasification] Corn Cob Gasifiers

Clarence Richey, Purdue and Robert Stwalley , Stwalley & Stwalley, developed
the downdraft channel gasifier for corncobs in the 1980s through the mid
1990s. 

Robert Stwalley is a professor at Purdue.

https://engineering.purdue.edu/ABE/People/ptProfile?resource_id=7402

http://patents.justia.com/patent/4452611

http://www.nrbp.org/papers/052.pdf

http://www.docstoc.com/docs/108067206/GASIFIER-PISTON-ENGINE-DECOUPLING

Pictures of the gasifier in:

http://www.midwestchptap.org/Archive/pdfs/061211JasperIN/Stwalley.pdf

At that time cobs were used for many purposes. We still have the Anderson
Cob Products manual on the uses for cobs from about 1980 (400 pp).My
favorite use for cobs was for stuffing cadavers. 

Now cobs are scattered on the field. There is no specialized equipment for
collecting and separating the cobs for use in conversion to liquid fuels.
After considerable field testing those projects (Poet, Abengoa) have shifted
to the stover or straw as a principle feedstock. The cob yield per acre is
very low which makes it expensive to collect or separate. 

Tom Miles

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