5,725,613
Mar. 10, 1998
United States Patent [19]
Reeves et al.
[54] METHOD TO REDUCE OXIDATIVE
DETERIORATION OF BULK MATERIALS
[75] Inventors: Robert A. Reeves. Arvada; Mark H.
Berggren. Golden; Charlie W.
Kenney. Littleton, all of Colo.
[73] Assignee: Hazen Research, Inc. Golden. Colo.
[21] AppL No.: 677,637
[22] Filed: Jul. 8, 1996
[51] Int. Cl.6 CI0L 9/00
[52] U.S. Cl 44/501; 44/591; 44/592;
44/620
[58] Field of Search 441501, 620
1111111111111111111111111111111111111111~lllllllllllmlI1IIIII1II
US005725613A
[11] Patent Number:
[45] Date of Patent:
OTHER PUBLICATIONS
Edwards. 1995. Catalysis Today, 23:59-66.
Keirn. "Industrial Uses of Carbon Dioxide". in Carbon
Dioxide as a Source ofCarbon, M. Aresta and G. Forti. eds..
D. Reidel Publishing Co.• 1987.23-31.
Rigsby et al.. "Coal self-heating: problems and solutions".
pp. 102-106.
Riley et aL. J. Coal Quality, Apr. 1987. pp. 64-67.
RipP. "Understanding coal pile hydrology can help BTU
loss in stored coal". pp. 146-150.
Sapienze et al.. "Carbon DioxidelWater for Coal Beneficiation".
in Mineral Matter and Ash in Coal, 1986 America
Chemical Society. pp. 50D-512.
Primary EXaminer-Ellen M. McAvoy
Attome)\ Agent, or Firm-Sheridan Ross P.C.
[56] References Cited [57] ABSTRACT
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U.S. PATENT DOCUMENTS
4/1966 Ellman et aI 3419
4/1978 Das 44/620
10/1979 Smith 44/1
8/1983 Li et aI. 44/1
8/1983 Bonnecaze 44/1
4/1985 Nakamura et aI 44/501
711986 Cargle et aI 4271220
9/1986 Chiang et aI 209/5
3/1987 Yan 44/1
1/1989 Siddoway et aI 44/501
5/1989 Bellow, Jr. et aI. 44/501
5/1989 Bixel et aI 44/501
2/1992 Clta et aI 44/501
Disclosed is a method to reduce oxidative deterioration of
bulk materials. Preferred embodiments of bulk materials
include solid fuel materials. such as coal. and bulk food
products. The method includes contacting a bulk material
with a heat transfer medium to reduce the temperature of the
bulk material below ambient temperature. and preferably
below about 100 C. In this manner, the rate of oxidation is
sufficiently low so that significant losses, such as the loss of
thermal values in of fuel material. are avoided. The heat
transfer medium can be solid or fluid and in a preferred
embodiment is liquid carbon dioxide or liquid nitrogen.
42 Claims, No Drawings
5,725,613
2
DEfAll..ED DESCRIPTION
The method includes directly contacting the bulk material
with a heat transfer medium to reduce the temperature of the
bulk material below an ambient temperature. In a preferred
embodiment. the temperature of the bulk material is reduced
5 to below about 10° C. In this manner. significant oxidative
deterioration of the bulk material is avoided. In the instance
of a solid fuel material. for example. loss of the thermal
value of the solid fuel material is reduced because the rate
of oxidative deterioration significantly slows with cooler
10 temperatures. Significant reductions in the rate of loss of
heating value can be attained for solid fuel material. For
example. fuel materials treated with the method of the
present invention can have a rate of loss of heating value of
less than about 0.5% per month.
The heat transfer medium can be solid. liquid or gas and
is substantially inert to the bulk material. In preferred
embodiments. the heat transfer medium can be carbon
dioxide. carbon monoxide. helium. nitrogen. argon or air. In
preferred embodiments. the heat transfer medium is carbon
20 dioxide or nitrogen. in particular. liquid and solid carbon
dioxide and liquid nitrogen.
The present invention includes conducting the process of
contacting a bulk material with a heat transfer medium at a
variety of times throughout the product life of the bulk
25 material. For example. the process can be conducted during
time periods when the bulk material is subject to a high
degree of mixing such as during size reduction steps and/or
loading or Unloading of the bulk material. In an alternative
embodiment. the step of contacting the bulk material with
30 the heat transfer medium can be conducted while the bulk
material is in a static state. such as in a storage pile.
Further embodiments of the present invention include
compositions which have been produced by conducting the
35 method of the present invention. Such compositions. for
example. include bulk materials in direct contact with a heat
transfer medium having temperatures within ranges according
to the method of the present invention.
The present invention concerns a method to reduce oxidative
deterioration of bulk materials. The term "bulk materials"
refers to any solid materials which are produced.
shipped and/or stored in quantities measured on a tonnage
basis. and preferably includes oxidizable and highly reactive
materials. Bulk materials can include solid fuel materials.
bulk food products. sulfide ores and carbon containing
materials. such as activated carbon and carbon black.
Solid fuel material. as used herein. generally refers to any
solid material which is combusted for some useful purpose.
More particularly. solid fuel materials can include coal.
upgraded coal products. and other solid fuels. The term coal
includes anthracite. bituminous coal. sub-bituminous coal
and lignite. The present invention is particularly suited for
55 bituminous coal. sub-bituminous coal and lignite. The term
upgraded coal product includes thermally-upgraded coal
products. coal products produced by beneficiation based
upon specific gravity separation. mechanically cleaned coal
products. and sized coal products such as stoker. breeze.
60 slack and fines. The present invention is particularly suited
for thermally-upgraded coal because of significantly
increased risk of oxidative deterioration and/or self-ignition.
Thermally upgraded products are likely to have a higher rate
of oxidation because of formation of reactive components
65 which increases the rate of oxidation. In addition. such
materials typically have had water removed to a significant
extent. If such materials are subsequently exposed to humid
BACKGROUND OF THE INVENTION
1
METHOD TO REDUCE OXIDATIVE
DETERIORATION OF BULK MATERIALS
FIELD OF THE INVENTION
The present invention relates to a method and composition
for reducing the oxidative deterioration of bulk materials.
In particular. the invention relates to reduction of
oxidative deterioration of solid fuel materials. such as coal.
When bulk materials contact the ambient environment.
they are subject to oxidative deterioration because of contact
with oxygen in air. Such oxidative deterioration can have
many negative effects. For example. when a solid fuel
material. such as coal. is being transported from a mine to a 15
utility or is in storage at a utility. it is subject to oxidation.
One negative aspect of such oxidative deterioration is a loss
in the thermal value of the coal. Depending on the type of
coal and its water content. among other factors. between 1%
and 5% of the thermal value of coal can be lost from the time
it is mined until the time at which it is consumed. These
losses are sizeable in the domestic United States utility
industry which consumes about 800 million tons of coal per
year. Such losses are particularly significant for low rank
coals such as lignite and sub-bituminous coals. especially
for such materials which have been upgraded by thermal
treatment to reduce moisture.
Moreover. low level oxidation of coal generates heat and
as such a reaction progresses. there is a significant risk of
certain coal materials self-igniting. resulting in a risk to
property and life.
Most efforts to reduce oxidative deterioration have
focused on reducing the risk of self-heating and thereby
self-ignition of coals. The problem has been addressed by a
variety of approaches. One such approach is by compacting
coal as it is transported or stored. By compacting coal.
significant reductions in coal surface area which contact the
ambient environment can be attained. Such a reduction of
surface area contact reduces the amount of coal available for 40
oxidation by the ambient environment Another approach
has been to flatten and trim coal piles to decrease the ability
of the coal pile to hold heat and therefore generate enough
heat through self-heating to self-ignite. In addition. contacting
coal materials with various fluids. such as hydrocarbon- 45
based materials. has been used.
While the more chronic problem of loss of economic
value of bulk materials. such as the loss of heating values in
coal. has been recognized and studied. adequate widespread
use of strategies for significantly reducing economic losses 50
from this problem have not been achieved. Therefore. a need
exists for reducing the oxidative deterioration of bulk materials.
SUMMARY OF THE INVENTION
The present invention includes a method to reduce oxidative
deterioration of bulk materials. particularly including
oxidizable and highly reactive bulk materials. In preferred
embodiments. the bulk materials in question include solid
fuel materials. bulk food products. sulfide ores and carbon
containing materials such as activated carbon and carbon
black. In further preferred embodiments. the solid fuel
material can be coal. upgraded coal products. oil shale. solid
biomass materials. refuse-derived (including municipal and
reclaimed refuse) fuels. coke. char. petroleum coke.
gilsonite. distillation by-products. wood by-product wastes.
shredded tires. peat and waste pond coal fines.
5,725.613
3 4
sidered. For example. warm air may be overly reactive with
some bulk materials. such as coal, but if the heat transfer
medium is cold air (e.g.. 4° C.). the degree of reactivity with
the coal may be acceptably low to be considered nonoxidizing.
Preferably, to be considered non-oxidizing. the
heat transfer medium of the present invention should not
oxidize the product or cause the product to become more
reactive to oxygen at a time subsequent to treatment with the
heat transfer medium. In a further embodiment. the heat
transfer medium can be inert (i.e.. non-reactive) to the bulk
material.
The heat transfer medium needs to be sufficiently cold so
that the temperature of the bulk material. prior to contact
with the heat transfer medium. can be reduced to within the
appropriate temperature range after contact. In a preferred
embodiment. the temperature of the heat transfer medium
prior to contact with the bulk medium is less than about -30°
C.. more preferably less than about -50° C. and most
preferably less than about -70° C.
The heat transfer medium can comprise carbon dioxide,
carbon monoxide, helium. nitrogen, argon. or air. More
preferably, the heat transfer medium can comprise carbon
dioxide, carbon monoxide. nitrogen or argon. In a preferred
embodiment, the heat transfer medium can comprise either
nitrogen or carbon dioxide. In a further preferred
embodiment, the heat transfer medium can comprise liquid
or solid carbon dioxide or liquid nitrogen. It will be recognized
that for a liquid or solid heat transfer medium which
is a gas at ambient temperatures of the bulk material, as the
heat transfer medium heats up, it will change phase to
become a gas. Such an evolution of gas over time, such as
the evolution of carbon dioxide gas from solid carbon
dioxide. has the benefit of excluding oxygen from contacting
the bulk material.
It will be appreciated that in the instance of a solid heat
transfer medium. smaller particle sizes will allow more
uniform cooling than for larger particle sizes. In the instance
of a solid heat transfer medium, the particle size of the
medium is preferably less than about 5 millimeter, more
preferably less than about 3 millimeter and most preferably
less than about 0.5 millimeter.
The step of contacting includes bringing the heat transfer
medium and the bulk material into sufficiently intimate
contact such that the bulk material is cooled to the desired
temperature. By contacting the bulk material directly with
the heat transfer medium. the heat transfer which occurs to
cool the bulk material is more efficient than through an
indirect heat transfer. Since the heat transfer medium is not
50 confined within, for example. tubes of a heat exchanger, a
more complete, effective and uniform cooling of the bulk
material can be achieved. Specific preferred methods for
contacting the heat transfer medium with the bulk material
are described in detail below.
It will be understood that the amount of heat transfer
medium needed to cool a given amount of bulk material will
depend on various factors, including the relative temperatures
of each. However, in a preferred embodiment. the
amount of heat transfer medium to be contacted with a bulk
material will be between about 0.5 and about 10 weight
percent. more preferably between about 1 and about 5
weight percent and even more preferably between about 1
and about 2 weight percent based on the weight of the bulk
material.
The step of contacting a bulk material with a heat transfer
medium of the present invention is preferably conducted
substantially in the absence of water. It will be recognized
environments, the materials will rewet thereby generating
heat through the heat of hydration.
Examples of other solid fuels embodied in the present
invention include, but are not limited to, oil shale. solid
biomass materials, refuse-derived (including municipal and 5
reclaimed refuse) fuels, coke. char, petroleum coke,
gilsonite. distillation by-products, wood by-product wastes,
shredded tires, peat and waste pond coal fines. The term
solid biomass can include, for example. wood wastes, agricultural
wastes. and grass. The term refuse-derived fuels can 10
include. for example, landfill material from which noncombustible
materials have been removed.
In one embodiment of the present invention. bulk materials
include bulk food products. Such bulk food products
include food products that tend to deteriorate in storage. 15
Since the food industry has concentrated on preservation of
high-end food products such as meats, dairy and vegetables,
there remains a need in the industry for low cost, effective
preservation of bulk food products such as bulk grains and
related by-products. According to the present invention. bulk 20
food products can include bulk grains. animal feed and
related by-products. Examples of such bulk grains include,
but are not limited to wheat. corn. soybeans, barley, oats, and
any other cereal grain that deteriorates in storage.
25 Examples of other oxidizable and highly reactive solid
bulk materials embodied in the present invention include,
but are not limited to sulfide ores. and carbon containing
materials. such as activated carbon and carbon black.
The present method includes directly contacting the bulk 30
material with a heat transfer medium to reduce the temperature
of the bulk material below ambient temperature. The
term ambient can refer to the temperature of the environment
in which the bulk material is produced. shipped and/or
stored. Alternatively, such term can include the temperature 35
at which the material existed prior to production. For
example. the temperature of coal in the earth is relatively
constant and will vary between about 10° C. and about 16°
C. In a preferred embodiment. the method of the present
invention includes reducing the temperature of the bulk 40
material with a heat transfer medium to below about 10° c..
preferably below about 5° c., more preferably below about
3° c.. and even more preferably between about 0° C. and
about 3° C. According to the present invention. reference to
the temperature of the bulk material can include the tem- 45
perature of an interior. such as the core of the material.
and/or a surface portion of the material. More particularly,
the temperature of the bulk material can refer to the temperature
of a portion of the material which is or can be in
contact with air or oxygen.
The appropriate temperature for cooling a bulk material
by contact with a heat transfer medium pursuant to the
present invention is selected such that unacceptable levels of
oxidative deterioration and/or self-heating are avoided. The
determination of the appropriate temperature may depend on 55
a variety offactors. including the nature of the bulk material,
the available time until consumption (i.e. storage time). the
rate of oxidation of the bulk material at various
temperatures. the cost of the heat transfer medium, and the
effects of extraneous factors on the product such as material 60
handling protocols.
The heat transfer medium of the present invention can be
solid or fluid (i.e.. liquid or gas). The heat transfer medium
is essentially non-oxidizing to the bulk material. It should be
noted that when considering whether the heat transfer 65
medium is non-oxidizing with regard to the bulk material.
the temperature of the heat transfer medium must be con5,725.613
6
In a further preferred embodiment of the present invention
where the heat transfer medium is not air. the step of
contacting the bulk material with a heat transfer medium
displaces ambient air from contact with the bulk material. In
5 this manner. the available oxygen for oxidation of the bulk
material is reduced.
In a further preferred embodiment of the present
invention. the heat transfer medium reacts with the surface
of the solid fuel material to passivate the solid fuel material
10 from oxidation by ambient air. Such a heat transfer medium
can. for instance. form new compounds on the surface of the
solid fuel material such that the surface is inactive. or less
reactive to oxidation by ambient air.
Methods of the present invention. including contacting a
15 bulk material with a heat transfer medium, can be conducted
at any time in the product life of the bulk material in question
to reduce oxidative deterioration in the future. For example.
in the case of solid fuel material such as coal. the step of
contacting can be conducted at any time from when the fuel
20 is removed from the ground or otherwise produced. until it
is ultimately consumed at a utility.
The method of contacting a bulk material with a heat
transfer medium is preferably conducted at a point in the
product life of the bulk material when the bulk material is
25 subject to a high degree of mixing or agitation for some
other purpose. In this manner. efficient contact of the bulk
material with the heat transfer medium can occur without the
added requirement of inducing substantial mixing or agitation
solely for the purpose of contact with the heat transfer
30 medium. In one embodiment. the step of contacting can
occur when the particle size of a bulk material is being
reduced. For example. in the instance of a solid fuel material
such as coal. the step of contacting can be conducted at the
mine at which the coal is recovered. Such a step of contact-
35 ing is advantageously conducted when run-of-mine coal is
initially crushed. As the run-of-mine coal is introduced into
a crusher. a stream of fluid heat transfer medium. preferably
liquid carbon dioxide or liquid nitrogen. can be introduced
at the same time. In this manner because the crusher induces
vigorous mixing of coal particles. intimate contact and
mixing of the heat transfer medium with the coal is also
achieved. In addition. or alternatively. a solid heat transfer
medium such as solid carbon dioxide can be introduced at a
mine location such as during a crushing step or subsequent
45 to the crushing as coal is loaded into a transport vehicle (i.e..
rail car or barge).
In a further preferred embodiment. the heat transfer
medium can be contacted with a bulk material when the bulk
material is subject to any material handling or processing
50 operation. such as when being transferred from one storage
or transport apparatus to another. such as during loading or
unloading from or to a transport vehicle or a storage facility.
For example. in the case of coal. which is transported by rail
or barge. when it arrives at a utility the coal is either
55 immediately consumed or sent to short- or long-term storage.
In any event. as the coal is unloaded from the rail or
barge vehicle. it is typically unloaded in such a manner that
the solid particulate coal becomes temporarily dispersed. At
this point in the unloading process. it is an advantageous
60 time for contacting with the heat transfer medium because of
the high degree of mixing available to achieve intimate
contact and efficient cooling. Thus. a fluid and/or solid heat
transfer medium. such as liquid or solid carbon dioxide or
liquid nitrogen. can be introduced at this point in a material
65 transfer process. For example. coal is typically unloaded
from a barge by scraping the coal from the cargo hold by a
bucket elevator or clamshell and is loaded onto a conveyor.
5
that many bulk materials and heat transfer media contain
some naturally occurring water. Reference to conducting the
present process in the absence of water refers to no water
being introduced in addition to any moisture naturally
occurring in the bulk material or heat transfer media.
A preferred embodiment of the present invention further
includes maintaining the bulk material at a cooled temperature
as described above for a time of at least about one day.
more preferably at least about one month and more preferably
at least about six months. For example. by maintaining
such temperatures for such time periods. oxidative deterioration
can be reduced during processing. transport and
storage of bulk materials.
The method of the present invention which includes
contacting a bulk material with a heat transfer medium to
effectively reduce the temperature. can be used in combination
with other techniques for reducing oxidative deterioration
and/or self-heating. For example. methods of the
present invention can further include sizing the bulk material
by removing small particles therefrom. In this manner. the
effective surface area of the bulk material available as an
oxidative surface is decreased. More particularly. this step
can include removing particles of the bulk material having
a particle size of less than about 5 millimeter.
In addition. methods of the present invention can also
include the step of compacting the bulk material. In this
manner. the available surface area for contact with ambient
air is reduced. More particularly. the step can include
compacting the bulk material to a bulk density of greater
than about 700 kgtm3
• and more preferably to a bulk density
of greater than about 1000 kglm3
•
Methods of the present invention will reduce the oxidative
deterioration of the bulk material in question. In the instance
where the bulk material is a solid fuel material. one measure
of the effectiveness of reducing oxidative deterioration is
measuring the rate of loss of the heating value of the fuel
material. For example. thermal loss can be measured by
comparing the moisture-ash-free heating value (MAP heating
value) of coal before and after storage. The MAPheating 40
value is computed by subtracting the dilution effects of
non-combustible ash and moisture from a heating value
measured on whole material by a laboratory calorimeter. The
MAP heating value is primarily a component of the hydrogen
and carbon in the coal. These two components are
oxidized to water vapor and carbon dioxide during storage.
Oxidation of hydrogen and carbon through low temperature
oxidation will reduce the MAP heating value.
In a preferred embodiment of methods of the present
invention. solid fuel material treated by methods of the
present invention has a rate of loss of heating value of less
than about 0.5% per month when stored at 2° C. in air. and
in a more preferred embodiment. the solid fuel material has
a rate of loss of heating value of less than about 0.1% per
month. and in a more preferred embodiment the solid fuel
material has a rate of loss of heating value of less than about
0.05% per month.
In the instance where the bulk material is a bulk food
product. such as bulk grain. other means of measuring the
effectiveness of reducing oxidative deterioration can be
employed. For example. a reduction in the concentration of
micro-organisms on grain could be used as a measurement
of the effectiveness of reducing oxidative deterioration in the
grain. The effectiveness of reducing oxidative deterioration
in a bulk food product could also be measured as a percentage
of spoilage of the food product over a given period of
time.
5}25.613
7 8
-58%
-85%
Percent reduction
O· C. by cooling
0.0034
0.0021
TABLE 1
24· C.
0.0081
0.0138
Rate of Oxygen Adsorption, k, for 24· C. and
O· C. Raw and Dried PRB Coal
Sample
Raw PRBCoal
Dtied PRB Coal
It will be noted that a reduction in the rate of oxygen
adsorption of 85% was achieved by cooling the dried coal
from 24° C. to 0° C. Similarly. a 58% reduction was seen
with the untreated raw coal. This example illustrates that
significant reductions in oxidative deterioration of fuel materials
can be achieved by practice of the present invention.
While various embodiments of the present invention have
been described in detail. it is apparent that modifications and
adaptations of those embodiments will occur to those skilled
in the art. It is to be expressly understood. however, that such
35 modifications and adaptations are within the scope of the
present invention, as set forth in the following claims.
What is claimed is:
1.A method to reduce oxidative deterioration of solid fuel
material comprising particles having a size of greater than
about 5 m.m. said method comprising the steps of:
directly contacting said solid fuel material with a heat
transfer medium. wherein said heat transfer medium is
not air; and
reducing a temperature of said solid fuel material below
about 10° C. through said contacting step.
2. A method as claimed in claim 1, wherein the temperature
of said solid fuel material is reduced to below about 5°
C.
3. A method. as claimed in claim 1, wherein the tempera50
ture of said solid fuel material is reduced to be between
about 0° C. and about 3° C.
4. Amethod, as claimed in claim 1. wherein said solid fuel
material is selected from the group consisting of coal,
upgraded coal products, oil shale. solid biomass materials,
55 refuse-derived fuels, coke, char, petroleum coke. gilsonite,
distillation by-products, wood by-product wastes, shredded
tires, peat and waste pond coal fines.
S. Amethod, as claimed in claim 1. wherein said solid fuel
material comprises coal and wherein said coal is selected
60 from the group consisting of bituminous coal. subbituminous
coal and lignite.
6. Amethod. as claimed in claim 1. wherein said solid fuel
material is an upgraded coal product and wherein said
upgraded coal product is selected from the group consisting
65 of thermally upgraded products, products beneficiated by
specific gravity separation, mechanically cleaned coal products
and sized coal products.
water bath maintained at 24° C. The other two vessels were
placed in an ice chest filled with ice and liquid water to
maintain the contents at 0° C. One of the dried samples was
placed in a 24°C. vessel and one in a 0° C. vessel. One
5 untreated sample was placed in a 24°C. vessel and in a 0°
C. vessel. The initial pressures within each vessel were
adjusted to 760 rom Hg (1 atmosphere at sea level). Air
pressure readings were read twice a day for 72 hours. Air
pressure decreases were reflective of oxygen adsorption by
10 the coal. Thus. air pressure decreases simulated the tendency
of coal to oxidize and therefore. the loss of thermal heating
value. The rates of oxygen adsorption are shown below in
Table 1.
EXAMPLES
Example 1
This example evaluates the rate of oxygen adsorption of
coal at different temperatures as a model to evaluate the
effect of cooling on oxidative deterioration of fuel materials.
Four loo-gram samples of o/.!-inch coal was obtained from
the Powder River Basin in Wyoming, U.S.A. 1Wo of the
samples were dried for 16 hours under a warminert nitrogen
atmosphere to reduce the moisture content of the coal from
approximately 27% to 6.27%. The remaining two samples
were not thermally treated. The samples contained, on a dry
basis, 7% ash. 44% volatile matter. 71% carbon, 4.8%
hydrogen, 0.6% sulfur and 11,820 BTUllb.
Each of the four samples of coal was placed in an airtight,
I-liter capacity. stainless steel test vessel. Each vessel was
fitted with an electronic solid-state pressure gauge capable
of measuring internal air pressure to within 0.015 psi. and a
septum fitting to allow air to be admitted to the vessel by
syringe. 1Wo of the vessels were placed in a circulating
At a transfer point, e,g., between two conveyors downstream
of the unloading process, a heat transfer medium such as
liquid carbon dioxide or liquid nitrogen can be added to the
coal before the coal is placed in storage.
In addition to conducting the method of the present
invention when the bulk material is subject to a high degree
of mixing or agitation, the step of contacting can be conducted
when the bulk material is static. For example, in the
instance of a solid fuel material, such as coal, which is in a
storage pile, the method of the present invention can include
contacting the heat transfer medium with the coal while it is
in storage or otherwise in a static condition. Such a step of
contacting can be achieved, for example. by inserting a pipe
or other distribution device into various points throughout a
storage pile and injecting an appropriate amount of, for 15
example, liquid carbon dioxide until appropriate cooling of
the coal pile is attained.
In the case wherein the bulk material is a bulk food
product, addition of a heat transfer medium is ideally
performed such that the food product is not crushed or 20
damaged. Therefore, the heat transfer medium can be contacted
with the bulk food product by adding such heat
transfer medium at a material handling transfer point during
the shipping and unloading of the food product.
25
In a further preferred embodiment. in the instance of solid
fuel materials, such as coal or upgraded coal products, the
heat transfer medium is liquid and/or solid carbon dioxide.
In this embodiment, carbon dioxide is recovered from the
flue gases at a utility by conventional stripping technology. 30
The carbon dioxide is then liquified or frozen solid and then
used, as described above, for contacting with coal or
upgraded coal product supplies which are incoming during
unloading from a transport vehicle or which are already in
storage.
Further embodiments of the present invention include
compositions which are produced by the processes of the
present invention. Such compositions include any of the
various bulk materials. as described above. which have been
contacted with an appropriate heat transfer medium, as 40
generally disclosed above, and cooled to a temperature
within the ranges as described above to reduce the oxidative
deterioration of the bulk material.
The following examples are provided for purposes of
illustration only and are not intended to limit the scope of the 45
invention.
5.725.613
9 10
* * * * *
26. A composition as claimed in claim 25, wherein the
temperature of said solid fuel material is reduced to below
about 50 C.
27. A composition, as claimed in claim 25. wherein the
5 temperature of said solid fuel material is reduced to be
between about 00 Co and about 3a C.
28. A composition, as claimed in claim 25, wherein said
solid fuel material is selected from the group consisting of
coal, upgraded coal products, oil shale, solid biomass
10 materials, refuse-derived fuels, coke, char. petroleum coke,
gilsonite, distillation by-products. wood by-product wastes.
shredded tires. peat and waste pond coal fines.
29. A composition, as claimed in claim 25, wherein said
solid fuel material comprises coal and wherein said coal is
15 selected from the group consisting of bituminous coal,
sub-bituminous coal and lignite.
30. A composition. as claimed in claim 25, wherein said
solid fuel material is an upgraded coal product and wherein
said upgraded coal product is selected from the group
20 consisting of thermally upgraded products. products beneficiated
by specific gravity separation, mechanically cleaned
coal products and sized coal products.
31. A composition, as claimed in claim 25. wherein said
heat transfer medium is selected from the group consisting
25 of carbon dioxide, carbon monoxide. helium, nitrogen,
argon and air.
32. A composition, as claimed in claim 25, wherein said
heat transfer medium comprises carbon dioxide.
33. A composition, as claimed in claim 25. wherein said
30 heat transfer medium comprises liquid carbon dioxide.
34. A composition, as claimed in claim 25. wherein said
solid fuel material has a rate of loss of heating value of less
than about O.5%/month.
35. A composition, as claimed in claim 25. wherein said
35 solid fuel material has a rate of loss of heating value of less
than about 0.1%/month.
36. A composition, as claimed in claim 25, wherein said
solid fuel material has a rate of loss of heating value of less
than about 0.05%/month.
37. A method to reduce oxidative deterioration of a bulk
material comprising particles having a size of less than 5
mm.. said method comprising the steps of:
directly contacting said bulk material with a heat transfer
medium; and
reducing a temperature of said bulk material below about
100 C. through said contacting step.
38. A method. as claimed in claim 37, wherein the
temperature of said bulk material is reduced to below about
50 C.
39. A method. as claimed in claim 37, wherein the
temperature of said bulk material is reduced to be between
about 00 C. and about 3a C.
40. A method, as claimed in claim 37, wherein said bulk
material comprises a bulk food or agricultural product.
55 41. A method, as claimed in claim 40, wherein said bulk
food product is selected from the group consisting of wheat,
corn, soybeans, barley, oats and animal feed.
42. A method, as claimed in claim 40. wherein said bulk
material is a carbon containing material selected from the
60 group consisting of activated carbon and carbon black.
7. A method, as claimed in claim 1, wherein said heat
transfer medium is selected from the group consisting of
carbon dioxide, carbon monoxide, helium, nitrogen, argon
and air.
8. A method, as claimed in claim 1, wherein said heat
transfer medium is selected from the group consisting of
carbon dioxide, carbon monoxide, nitrogen and argon.
9. A method, as claimed in claim 1, wherein said heat
transfer medium comprises carbon dioxide.
10. A method, as claimed in claim 1, wherein said heat
transfer medium comprises liquid carbon dioxide.
11. A method, as claimed in claim 1, wherein said heat
transfer medium comprises solid carbon dioxide.
12. A method, as claimed in claim 1, wherein said heat
transfer medium comprises liquid nitrogen.
13. A method. as claimed in claim 1, further comprising
removing particles of said fuel material having a particle
size of less than about 5 millimeter.
14. A method. as claimed in claim 1, further comprising
compacting said solid fuel material.
15. A method, as claimed in claim 1, further comprising
compacting said solid fuel material to a bulk density of
greater than about 700 kglm3
•
16. A method, as claimed in claim 1, further comprising
compacting said solid fuel material to a bulk density of
greater than about 1000 kg/m3
•
17. A method, as claimed in claim 1, wherein said solid
fuel material has a rate of loss of heating value of less than
about 0.5%/month.
18. A method, as claimed in claim 1, wherein said solid
fuel material has a rate of loss of heating value of less than
about 0.1%/month.
19. A method, as claimed in claim 1, wherein said solid
fuel material has a rate of loss of heating value of less than
about 0.05%/month.
20. A method, as claimed in claim 1, wherein said step of
contacting said heat transfer medium and said solid fuel
material displaces ambient air from contact with said fuel
material.
21. A method, as claimed in claim 1, wherein said heat 40
transfer medium reacts with the surface of said solid fuel
material to passivate said solid fuel material from oxidation
by ambient air.
22. A method. as claimed in claim 1, wherein said step of
contacting comprises contacting said heat transfer medium 45
with said solid fuel material during crushing of said solid
fuel material.
23. A method, as claimed in claim 1, wherein said step of
contacting comprises contacting said heat transfer medium
with said solid fuel material during a material handling or 50
processing operation.
24. A method, as claimed in claim 1, wherein said step of
contacting comprises contacting said heat transfer medium
with said solid fuel material while said solid fuel material is
in a static condition.
25. A composition comprising:
a solid fuel material, comprising particles having a size of
greater than about 5 mm; and
a heat transfer medium being in direct contact with said
solid fuel material, wherein said composition has a
temperature below about 100 C. and said heat transfer
medium is not air.
UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION
PATENT NO. : 5,725,613
DATED : March 10, 1998
INVENTOR(S) : Reeves et al
It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
corrected as shown below:
Column 9, line 3, after nitrogen delete "," and insert --and--.
Column 9, line 4, delete --and air--.
Column 10, line 25, after nitrogen delete "," and insert --and--.
Column 10, line 26, delete --and air--.
Signed and Sealed this
Twenty-seventh Day ofApril, 1999
Attest:
Attesting Officer
Q. TODD DICKINSON
Acrin!? Commissioner of PateUf.'lllnd Trademarks