U.S. patent application number 09/755273 was filed with the patent office on 2001-05-17 for aqueous, pumpable fluids from solid carbonaceous materials (law847).
Invention is credited to Brons, Cornelius Hendrick, Savage, David William, Varadaraj, Ramesh.
Application Number | 20010001308 09/755273 |
Document ID | / |
Family ID | 27401774 |
Filed Date | 2001-05-17 |
United States Patent
Application |
20010001308 |
Kind Code |
A1 |
Varadaraj, Ramesh ; et
al. |
May 17, 2001 |
Aqueous, pumpable fluids from solid carbonaceous materials
(law847)
Abstract
The invention is a method for forming a solid carbonaceous
material into a pumpable fluid by combining the solid with an
aqueous treatment solution and then subjecting the mixture to
shearing forces. The solid carbonaceous material can be deasphalter
unit rock ("DAU rock"), coke, and mixtures of DAU rock and coke.
Aqueous treatment solutions contain a water soluble polymer.
Inventors: |
Varadaraj, Ramesh;
(Flemington, NJ) ; Brons, Cornelius Hendrick;
(Washington, NJ) ; Savage, David William;
(Lebanon, NJ) |
Correspondence
Address: |
Linda M. Scuorzo
ExxonMobil Research and Engineering Company
P.O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
27401774 |
Appl. No.: |
09/755273 |
Filed: |
January 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09755273 |
Jan 5, 2001 |
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09350861 |
Jul 9, 1999 |
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09350861 |
Jul 9, 1999 |
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09265174 |
Mar 9, 1999 |
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09265174 |
Mar 9, 1999 |
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08889744 |
Jul 7, 1997 |
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Current U.S.
Class: |
516/38 |
Current CPC
Class: |
B01F 23/511 20220101;
C09K 23/00 20220101; C10L 1/326 20130101; C09K 23/16 20220101; Y10T
137/0391 20150401 |
Class at
Publication: |
516/38 |
International
Class: |
B01F 017/00 |
Claims
What is claimed is:
1. A method for forming a pumpable admixture, the method consisting
essentially of: admixing carbonaceous solid particles less than 177
in size wherein the solid carbonaceous particles are selected from
the group consisting of coke, DAU rock and mixtures thereof, and an
aqueous treatment solution wherein the amount of treatment solution
ranges from about 20 wt % to about 60 wt % of the total weight of
carbonaceous solid and treatment solution and wherein the aqueous
treatment solution comprises a water-soluble polymer capable of
viscosifying water, the polymer being present in an amount ranging
from about 10 to about 500 ppm; and then subjecting the admixture
to shearing forces for a time sufficient to reduce the admixture's
viscosity to below about 20,000 cPs at ambient temperature.
2. The method of claim 1 wherein the carbonaceous solid is obtained
by comminuting the carbonaceous solid.
3. The method of claim 2 wherein the carbonaceous solid is
comminuted in the presence of the treatment solution.
4. The method of claim 3 wherein the polymer in xanthan gum.
5. An aqueous, pumpable composition having a viscosity at ambient
temperature below about 20,000 cPs comprising a carbonaceous solid
consisting of particles less than 177.mu. in size wherein the
carbonaceous solid is selected from the group consisting of coke,
DAU rock, and mixtures thereof and an aqueous treatment solution
comprising a water soluble polymer capable of viscosifying water,
the polymer being present in an amount ranging from about 10 to
about 500 ppm, wherein the concentration of the carbonaceous solid
in the treatment solution ranges from about 40 wt % to about 70 wt
% based on the weight of the carbonaceous material and water.
6. The method of claim 5 wherein the polymer is xanthan gum.
Description
CROSS REFERENCE TO RELATED APPLICATION
1. This application is a Divisional of U.S. Ser. No. 09/350,861
filed Jul. 9, 1999 based on Continuation-In-Part under 37 CFR
1.53(b) of U.S. Ser. No. 09/265,174 filed Mar. 9, 1999, which is a
Continuation-In-Part under 37 CFR 1.53(b) of U.S. Ser. No. 889,744
filed Jul. 8, 1997.
2. U.S. Ser. No. 350,861 FILED Jul. 9, 1999
3. BASED ON: Continuation-In-Part under 37 CFR 1.53(b) of U.S. Ser.
No. 09/265,174 filed Mar. 9, 1999, which is a Continuation-In-Part
under 37 CFR 1.53(b) of U.S. Ser. No. 889,744 filed Jul. 8, 1997
which is based on Patent Memoranda 96CL 063 and 96CL 094
CROSS REFERENCE TO RELATED APPLICATION
4. This application is a Continuation-In-Part under 37 CFR 1.53(b)
of U.S. Ser. No. 09/265,174 filed Mar. 9, 1999, which is a
Continuation-In-Part under 37 CFR 1.53(b) of U.S. Ser. No. 889,744
filed Jul. 8, 1997.
5. This application is a Continuation-In-Part under 37 CFR 1.53(b)
of U.S. Ser. No. 09/265,174 filed Mar. 9, 1999, which is a
Continuation-In-Part under 37 CFR 1.53(b) of U.S. Ser. No. 889,744
filed Jul. 8, 1997.
FIELD OF THE INVENTION
6. The invention relates generally to forming pumpable compositions
from solid materials. More specifically, the invention relates to a
fuel in the form of a pumpable fluid formed from solid carbonaceous
materials.
BACKGROUND OF THE INVENTION
7. Solid carbonaceous materials are often formed as by-products of
petroleum refining and separation. De-Asphalting Unit (DAU) rock
and coke formed in coking units are examples of such materials.
These materials are useful as fuels for power generation and also
in reactions such as hydrocarbon partial oxidation.
8. Solvent de-asphalting is one method for upgrading resids
produced in vacuum and atmospheric pipestills. One by-product of
solvent de-asphalting is deasphalting unit ("DAU") rock. DAU rock
is a solid carbonaceous material that has a high concentration of
Conradson carbon ("Concarbon") and metals. The presence of
Concarbon and metals diminishes DAU rock's usefulness as a feed for
further refining and leads to very high disposal costs. However,
this material is useful as a feed for power generation and for the
production of CO and hydrogen, a mixture frequently referred to as
syngas, from the partial oxidation of hydrocarbons such as
methane.
9. Cokers are also used for refining resids produced in atmospheric
and vacuum pipestills. Petroleum/refinery coke ("coke") is the
solid carbonaceous material formed in the coker. Coke generally
forms in one of three solid morphologies. Most petroleum coke is
formed as "sponge coke", a hard porous irregularly shaped material
ranging in size from about 20 inches to a fine dust. Some coke is
formed in the shape of very fine needle shaped particles called
needle coke. The least common form of coke is "shot" coke, named
from the clusters of shot-sized pellets in which it is most often
found.
10. Petroleum coke does not have sufficient strength to be useful
in the production of pig iron or as foundry coke. Additionally, the
high concentration of metals in petroleum source results in high
disposal costs. However, like DAU rock, this material is useful as
a fuel for power generation and syngas production.
11. One problem associated with the use of coke or DAU rock as a
fuel results from the logistical difficulties and high
transportation costs incurred in moving the fuel from a refinery to
a power plant. Certain processes described in the art require an
emulsion of two liquids (e.g., U.S. Pat. Nos. 4,293,459 and
5,478,365). In such cases the presence of hot (liquefied) heavy
hydrocarbon is required with a strong emulsifying agent There the
hydrocarbon is not present as solid particles but must itself be
liquefied.
12. However, if the DAU rock or coke could be formed into an
aqueous, pumpable fluid, the fuel could be transported easily and
at low cost through conventional pipelines. One should also note
that the presence of water in the pumpable fluid along with the
feed is advantageous in power generation, where water is frequently
required for processes such as steam reforming.
13. There is therefore is a need for a method of forming coke or
DAU rock into an aqueous, pumpable fluid.
14. Certain aqueous slurries of coal and coke are known. These
slurries are formed by combining coal or coke with an aqueous fluid
containing polymers such as gum tragacanth, gum arabic, guar gum,
xanthan gum, starch, CM-cellulose, unhydrolyzed gelatin,
carageenan, and hydroxymethyl cellulose. Treatment solutions known
in the art may also contain anionic or non-ionic surfactants such
lignosulfonate and polyethylene oxide surfactants. Such treatment
solutions have surfactant and polymer concentration in the range of
about 0.5 wt % (about 5,000 ppm) to about 5 wt %.
15. One object of the present invention is the production of an
aqueous treatment solution having reduced polymer concentration
alone that is capable of forming DAU rock, coke, and mixtures
thereof into a pumpable fluid.
SUMMARY OF THE INVENTION
16. One embodiment is a method for forming an aqueous, pumpable
admixture, by (a) admixing carbonaceous solid particles less than
177 microns in size wherein the solid carbonaceous particles are
selected from the group consisting of coke, DAU rock, and mixtures
thereof, and an aqueous treatment solution wherein the amount of
treatment solution ranges from about 20 wt % to about 60 wt % of
the total weight of carbonaceous solid and treatment solution and
wherein the aqueous treatment solution comprises a water-soluble
polymer capable of viscosifying water, the polymer being present in
an amount ranging from about 10 to about 500 ppm; and then (b)
subjecting the admixture to shearing forces for a time sufficient
to reduce the admixture's viscosity to below about 20,000 cPs at
ambient temperature (25.degree. C.).
17. Another embodiment is an aqueous, pumpable composition having a
viscosity below about 20,000 cPs comprising a carbonaceous solid
selected from the group consisting of coke, DAU rock, and mixtures
thereof and an aqueous treatment solution comprising a water
soluble polymer capable of viscosifying water, the polymer being
present in an amount ranging from about 10 to about 500 ppm,
wherein the concentration of the carbonaceous solid in the
treatment solution ranges from about 40 wt % to about 70 wt % based
on the weight of the carbonaceous material and water.
18. The invention may comprise, consist or consist essentially of
the elements or steps recited herein and may be practiced in the
absence of a limitation not disclosed as required.
BRIEF DESCRIPTION OF THE DRAWINGS
19. FIG. 1 shows the behavior of an admixture of DAU rock and
treatment solution containing xanthan gum polymer as a function of
shear rate.
20. FIG. 2 shows the behavior of an admixture of DAU rock and a
treatment solution treatment solution formed from 100 ppm
polyacrylamide.
21. FIG. 3 shows the behavior of an admixture of coke and treatment
solution containing xanthan gum polymer as a function of shear
rate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
22. A preferred embodiment of the invention is directed towards
forming aqueous, pumpable fluids from solid carbonaceous materials
as described herein. DAU rock, coke, and mixtures thereof are
examples of solid carbonaceous materials that are useful in the
practice of the present embodiment. In the practice of the
invention, solid carbonaceous material having a particle size
ranging from about 10.mu. to about 177.mu. is combined with an
aqueous treatment solution containing a small amount of polymer.
Asphalts are not included within the term DAU rock. The DAU rock
used is formed by contacting crude oil residuum obtained from
atmospheric or vacuum pipestills with a suitable amount of alkane
deasphalting solvent. These solvents are known in the art and
include propane, butane, pentane and hexane as are treatment
conditions are known to those skilled in the art. Typical
conditions include a ratio of feed to deasphalting solvent from 1:4
to 1:14. However, solvent ratios, temperatures and pressures for
deasphalting are known to those skilled in the art. The treatment
results in a deasphalted oil ("DAO") and a solvent insoluble
material termed DAU Rock.
23. In cases where the solid carbonaceous material is in the form
of particles exceeding 177.mu. in size, some method of separating
the oversized particles such as sieving must be employed to ensure
that particles larger than 177.mu. are excluded. Alternatively,
some method of comminuting, such as wet grinding, dry grinding, or
ball milling the solid carbonaceous material may be used to reduce
the particle size to below 177.mu.. Combinations of comminuting and
sieving may also be used in connection with obtaining particles in
the proper size range. In cases where particle size must be
reduced, ball milling is preferable to dry grinding. Ball milling
is preferred because it can be conducted in the presence of the
treatment solution and because ball milling results in particles
that are smaller and more uniformly sized. Consequently, ball
milling will generally not require a separate sieving step. In any
event the resulting particles will be essentially non-spherical
i.e., irregularly shaped.
24. Once the proper particle size is obtained, the solid
carbonaceous material is combined with a treatment solution.
Importantly, the treatment solution is not merely added to the
solid carbonaceous material. The treatment solution and solid
carbonaceous material are mixed until the particles of solid
carbonaceous material have been wetted by the treatment solution.
The treatment solution is an aqueous solution wherein the amount of
water present is sufficient to provide a solid to water ratio
ranging from about 40:60 to about 80:20. Preferably, the solid to
water ratio will range from about 60:40 to about 70:30. The solid
carbonaceous material should remain as solid particles in the
aqueous treatment fluid. This is distinguished from those described
in the art wherein hydrocarbon is at a temperature greater than its
softening point (i.e., is a liquid) and is mixed with water in the
presence of surfactant or emulsifying agent at high temperatures
and pressures. Thus, in the prior art the treatment solution is a
liquid-liquid system during preparation whereas the present
embodiment is practiced as a solid-liquid system during the
formation of the aqueous pumpable fluid and in the absence of a
surfactant The nature and properties of complex hydrocarbon-water
fluids originating from liquid-liquid preparation are significantly
different form those originating from solid-liquid
preparations.
25. The treatment solution contains water and a water-soluble
polymer that is capable of viscosifying water. A surfactant is
generally lower in molecular weight, will not viscosity water at
the 10 to 500 ppm concentration range and contain distinct
hydrophillic and hydrophobic functional groups per molecule. The
polymer may be a functionalized polymer. Polymers that are useful
in the practice of the invention include polyacrylamide polymer and
xanthan gum. The polymer should be present in an amount ranging
from about 10 to about 500 ppm. The preferred polymer is xanthan
gum. The addition of this viscosifying or thickening agent alters
the viscosity of the aqueous liquid and alters the wettability of
solid carbonaceous material. As a result, the process can be
practiced with a treatment solution comprising water and
polymer.
26. Surprisingly, it was discovered that among the polymers known
to form aqueous slurries with carbonaceous materials, xanthan gum
was capable of forming pumpable fluids at very low concentration,
on the order of about 10 to 100 ppm, with the mixture of solid
carbonaceous material and treatment solution subjected to shearing
at about 100 rpm. This is unexpected because there is no surfactant
or emulsifier required Additionally, lower concentrations of
polymer being active without the surfactant or emulsifier indicates
the stabilizing properties for the aqueous polymer solution at low
concentrations is unexpected.
27. The mixture's viscosity decreases when it is subjected to
shearing forces at ambient temperature (20-26.degree. C.) and
atmospheric pressure. The viscosity decreases from that of a
viscous fluid (approximately 20,000 cPs and above) to that of an
aqueous pumpable fluid (below approximately 20,000 cPs) at a shear
rate of about 100 rpm. The mixture is mixed for sufficient time and
at a optimum rate so that the viscosity of the mixture is decreased
to a value in the range that is pumpable. For example, after the
initial shearing at 100 rpm, the mixture is equilibrated at rest
for 48 hours. After 48 hours the viscosity behavior is repeatable
indicating stability of the slurry.
28. In cases in which the solid is coke, the same general behavior
seen for DAU rock is observed.
29. Mixtures of treatment solution and-solid may be readily
transported via pipeline to power generating equipment after
shearing decreases the mixture's viscosity into the range of a
pumpable fluid.
EXAMPLES
Example 1
30. A DAU rock specimen was subjected to dry grinding and sieving
in order to produce a DAU rock powder with a particle size ranging
upwards to about 177.mu.. Admixtures of DAU rock and three
different treatment solutions were prepared and subjected to
shearing forces while monitoring admixture viscosity. The results
of those measurements are shown in FIG. 1. Xanthan gum was used as
the polymer. The points represented by triangles show the viscosity
of a treatment solution containing 60 wt % DAU rock, 40 wt % water,
12.5 ppm polymer.
31. FIG. 1 shows a decrease in viscosity as shear rate is
increased. Shear of 100 rpms produced a pumpable solution.
32. The sample was then allowed to equilibrate for two days at
ambient temperature (25.degree. C.) and pressure, and the viscosity
measurements were repeated at the end of that interval. No
significant changes in viscosity was observed indicating the slurry
was stable over a 48 hour time period.
Example 2
33. For comparison purposes, a treatment solution using
polyacrylamide in place of xanthan gum was tested. The
polyacrylamide had an average molecular weight of 5.times.10.sup.6
and was obtained from Polysciences Inc., Warrington, Pa. FIG. 2
shows the variation of shear rate with viscosity for this rock
slurry. While it is possible to attain viscosity levels similar to
those shown in FIG. 1, polyacrylamide concentration must be in the
range of about 100 ppm.
Example 3
34. A Flexicoke specimen coke was used "as received" from a
refinery Flexicoker unit Sieving the coke resulted in the removal
of coke particles larger than 177 microns. Admixtures of coke and
two different treatment solutions were prepared and subjected to
shearing forces while monitoring admixture viscosity. The results
of those measurements are shown in FIG. 3. The points represented
by triangles show the viscosity of a treatment solution containing
60 wt % coke, 40 wt % water, 12.5 ppm xanthan polymer.
35. A decrease in viscosity with shear rate is observed similar to
the DAU rock slurry.
36. The sample was then allowed to equilibrate for two days at
ambient temperature and pressure, and the viscosity measurements
were repeated at the end of that interval. No significant change in
viscosity was observed indicating the slurry was stable over a 48
hour period.
* * * * *