U.S. patent application number 12/359560 was filed with the patent office on 2009-07-30 for treated refractory material and methods of making.
This patent application is currently assigned to General Electric Company. Invention is credited to Wei Chen, Peter Joel Meschter, Roman Shuba, Wade Albert Taber.
Application Number | 20090188347 12/359560 |
Document ID | / |
Family ID | 42111947 |
Filed Date | 2009-07-30 |
United States Patent
Application |
20090188347 |
Kind Code |
A1 |
Taber; Wade Albert ; et
al. |
July 30, 2009 |
TREATED REFRACTORY MATERIAL AND METHODS OF MAKING
Abstract
A treated refractory material includes a refractory material
having a plurality of pores, wherein the refractory material
comprises aluminum oxide, silicon oxide, magnesium oxide, chromium
oxide, zirconium oxide, titanium oxide, calcium oxide, fireclay,
silicon carbide, tungsten, mullite, dolomite, magnesite, magnesium
aluminum oxide, chromite, magnetite, or a combination comprising at
least one of the foregoing; and a protective material disposed
within the plurality of pores of the refractory material, wherein
the protective material is selected from the group consisting of
aluminum oxide, chromium oxide, silica, rare earth oxides, rare
earth zirconates, titanium oxide, mullite, zirconium oxide,
zirconium silicate, yttrium oxide, magnesium oxide, iron oxide, and
blends thereof.
Inventors: |
Taber; Wade Albert; (Katy,
TX) ; Chen; Wei; (Sugar Land, TX) ; Meschter;
Peter Joel; (Niskayuna, NY) ; Shuba; Roman;
(Niskayuna, NY) |
Correspondence
Address: |
CANTOR COLBURN, LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
42111947 |
Appl. No.: |
12/359560 |
Filed: |
January 26, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11683260 |
Mar 7, 2007 |
|
|
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12359560 |
|
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Current U.S.
Class: |
75/301 ;
75/330 |
Current CPC
Class: |
C04B 41/5007 20130101;
C04B 41/87 20130101; C04B 41/4535 20130101; B82Y 30/00 20130101;
C04B 2235/3244 20130101; C04B 35/657 20130101; C04B 41/009
20130101; C04B 2235/3241 20130101; C04B 41/5031 20130101; C04B
2235/3217 20130101; C04B 2235/3229 20130101; C04B 2235/443
20130101; C04B 2235/449 20130101; C04B 2235/616 20130101; C04B
2235/77 20130101; C04B 2235/3418 20130101; C04B 35/12 20130101;
C04B 2235/5454 20130101; C04B 2235/9669 20130101; C04B 2235/3224
20130101; C04B 41/85 20130101; C04B 41/4535 20130101; C04B 41/455
20130101; C04B 41/5033 20130101; C04B 41/4535 20130101; C04B 41/455
20130101; C04B 41/5031 20130101; C04B 41/4535 20130101; C04B 41/455
20130101; C04B 41/5045 20130101; C04B 41/4535 20130101; C04B 41/455
20130101; C04B 41/5042 20130101; C04B 41/009 20130101; C04B 35/047
20130101; C04B 41/009 20130101; C04B 35/00 20130101; C04B 41/5031
20130101; C04B 41/4539 20130101; C04B 41/4549 20130101; C04B
41/5007 20130101; C04B 41/4535 20130101; C04B 41/009 20130101; C04B
35/12 20130101; C04B 41/009 20130101; C04B 38/00 20130101 |
Class at
Publication: |
75/301 ;
75/330 |
International
Class: |
C21B 7/06 20060101
C21B007/06 |
Claims
1. A treated refractory material, comprising: a refractory material
having a plurality of pores, wherein the refractory material
comprises aluminum oxide, silicon oxide, magnesium oxide, chromium
oxide, zirconium oxide, titanium oxide, calcium oxide, fireclay,
silicon carbide, tungsten, mullite, dolomite, magnesite, magnesium
aluminum oxide, chromite, magnetite, or a combination comprising at
least one of the foregoing; and a protective material disposed
within the plurality of pores of the refractory material, wherein
the protective material is selected from the group consisting of
aluminum oxide, chromium oxide, silica, rare earth oxides, rare
earth zirconates, titanium oxide, mullite, zirconium oxide,
zirconium silicate, yttrium oxide, magnesium oxide, iron oxide, and
blends thereof.
2. The treated refractory material of claim 1, wherein the rare
earth oxides comprise oxides of rare earth elements selected from
the group consisting of lanthanum, cerium, praseodymium, neodymium,
promethium, samarium, europium, gadolinium, terbium, dysprosium,
holmium, erbium, thulium, ytterbium and lutetium.
3. The treated refractory material of claim 1, wherein the rare
earth zirconate has a formula of RE.sub.2Zr.sub.2O.sub.7, where RE
is a rare earth element selected from the group consisting of
lanthanum, cerium, praseodymium, neodymium, promethium, samarium,
europium, gadolinium, terbium, dysprosium, holmium, erbium and
ytterbium.
4. The treated refractory material of claim 1, wherein the
protective material fills from about 3 to about 60 percent of the
volume of the plurality of pores in the refractory material.
5. The treated refractory material of claim 1, wherein the
protective material is a powder.
6. The treated refractory material of claim 5, wherein the
protective material has a particle size in the range of from about
5 nm to about 200 .mu.m.
7. The treated refractory material of claim 1, wherein an amount of
the protective material comprises from about 2 to about 20 percent
by volume based on the total volume of the refractory material.
8. An article comprising the treated refractory material of claim
1.
9. The article of claim 8, wherein the article comprises a
pre-formed structure.
10. The article of claim 9, wherein the pre-formed structure
comprises a brick, block, tile, or a combination comprising at
least one of the foregoing.
11. The article of claim 8, wherein the article comprises a
monolithic.
12. The article of claim 11, wherein the monolith comprises a
castable, moldable, ramming mix, gunning mix, mortar, refractory
plastic, or combination comprising at least one of the
foregoing.
13. The article of claim 1, wherein the article comprises a
combination of a pre-formed structure and a monolithic portion.
14. A process for making a treated refractory body, comprising:
adding a protective material to an existing refractory body
comprising a refractory material, wherein the refractory material
comprises aluminum oxide, silicon oxide, magnesium oxide, chromium
oxide, zirconium oxide, titanium oxide, calcium oxide, fireclay,
silicon carbide, tungsten, mullite, dolomite, magnesite, magnesium
aluminum oxide, chromite, magnetite, or a combination comprising at
least one of the foregoing, and the protective material is selected
from the group consisting of aluminum oxide, chromium oxide,
silica, rare earth oxides, rare earth zirconates, titanium oxide,
mullite, zirconium oxide, zirconium silicate, yttrium oxide,
magnesium oxide, iron oxide, and blends thereof.
15. The process of claim 14, further comprising forming the
existing refractory body and sintering the existing refractory
body, wherein the body comprises a brick, block, tile, or a
combination comprising at least one of the foregoing.
16. The process of claim 14, wherein the rare earth oxides comprise
oxides of rare earth elements selected from the group consisting of
lanthanum, cerium, praseodymium, neodymium, promethium, samarium,
europium, gadolinium, terbium, dysprosium, holmium, erbium,
thulium, ytterbium and lutetium.
17. The process of claim 14, wherein the rare earth zirconate has a
formula of RE.sub.2Zr.sub.2O.sub.7, where RE is a rare earth
element selected from the group consisting of lanthanum, cerium,
praseodymium, neodymium, promethium, samarium, europium,
gadolinium, terbium, dysprosium, holmium, erbium and ytterbium.
18. The process of claim 14, wherein the protective material is
added to a plurality of pores in the refractory material by
painting, spraying, dipping, coating or vacuum infiltration.
19. The process of claim 14, further comprising sintering the
treated refractory body, wherein the refractory material and the
protective material do not comprise the same compounds.
20. The process of claim 18, further comprising forming a slurry
comprising the protective material before adding the protective
material to the refractory material.
21. The process of claim 14, wherein the protective material is
added to the refractory material after the refractory material has
been disposed in a gasifier.
22. A process for making a treated refractory material comprising:
blending a refractory material with a protective material and/or a
precursor of a protective material, wherein the refractory material
comprises aluminum oxide, silicon oxide, magnesium oxide, chromium
oxide, zirconium oxide, titanium oxide, calcium oxide, fireclay,
silicon carbide, tungsten, mullite, dolomite, magnesite, magnesium
aluminum oxide, chromite, magnetite, or a combination comprising at
least one of the foregoing, and sintering the blend, wherein the
protective material and/or the precursor of the protective material
is in elemental or compound form and comprises an element not
comprised in the refractory material selected from the group
consisting of silicon, rare earth elements, zirconium, titanium,
yttrium, magnesium, iron, and blends thereof.
23. The process of claim 22, wherein the protective material is
added in an amount of from about 1 to about 10 percent by weight
based on the weight of the blend.
24. The process of claim 22, further comprising forming the blend
into a selected one or both of a pre-formed structure and a
monolith and sintering the blend at a temperature from about
1000.degree. C. to about 1800.degree. C. for about 1 to about 160
hours.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of and claims
benefit to the legally related application, U.S. Non-provisional
patent application Ser. No. 11/683,260 filed Mar. 7, 2007, which is
fully incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] In a slagging gasifier, solid feedstocks such as coal or
coke are partially oxidized at about 1300 to 1600 degrees Celsius
to produce a mixture of carbon monoxide, carbon dioxide, hydrogen,
and water (often referred to as a `syngas`). The coal can typically
contain up to about 5 to 25 percent by weight of inorganic minerals
that combine to form a low viscosity molten slag, which contains
silicon oxide, aluminum oxide, calcium oxide, and iron oxide.
[0003] The walls of the gasifier are lined with refractory
material, which is currently prepared from chromium oxide
(Cr.sub.2O.sub.3) grains or a blend of Cr.sub.2O.sub.3 and aluminum
oxide grains, formed into bricks and sintered. The refractory
material has a connected pore structure and is quite porous (e.g.
up to 20% porosity by volume). As the slag flows along the walls of
the gasifier, it infiltrates the pores in the refractory material.
This infiltration causes refractory degradation through a
combination of grain dissolution, grain undercutting and
macro-cracking.
[0004] An improved treated refractory material for reducing the
penetration of liquid slag and an improved method for treating the
refractory material would be desirable.
BRIEF DESCRIPTION OF THE INVENTION
[0005] In one embodiment, a treated refractory material comprises:
a refractory material having a plurality of pores, wherein the
refractory material comprises aluminum oxide, silicon oxide,
magnesium oxide, chromium oxide, zirconium oxide, titanium oxide,
calcium oxide, fireclay, silicon carbide, tungsten, mullite,
dolomite, magnesite, magnesium aluminum oxide, chromite, magnetite,
or a combination comprising at least one of the foregoing; and a
protective material disposed within the plurality of pores of the
refractory material, wherein the protective material is selected
from the group consisting of aluminum oxide, chromium oxide,
silica, rare earth oxides, rare earth zirconates, titanium oxide,
mullite, zirconium oxide, zirconium silicate, yttrium oxide,
magnesium oxide, iron oxide, and blends thereof.
[0006] In another embodiment, an article includes the treated
refractory material and can be a pre-formed structure, a monolith,
or a combination thereof.
[0007] In another embodiment, a process for making a treated
refractory body, includes adding a protective material to an
existing refractory body comprising a refractory material, wherein
the refractory material comprises aluminum oxide, silicon oxide,
magnesium oxide, chromium oxide, zirconium oxide, titanium oxide,
calcium oxide, fireclay, silicon carbide, tungsten, mullite,
dolomite, magnesite, magnesium aluminum oxide, chromite, magnetite,
or a combination comprising at least one of the foregoing, and the
protective material is selected from the group consisting of
aluminum oxide, chromium oxide, silica, rare earth oxides, rare
earth zirconates, titanium oxide, mullite, zirconium oxide,
zirconium silicate, yttrium oxide, magnesium oxide, iron oxide, and
blends thereof.
[0008] In still another embodiment, a process for making a
refractory material includes blending the refractory material with
a protective material and/or a precursor of a protective material,
wherein the refractory material comprises aluminum oxide, silicon
oxide, magnesium oxide, chromium oxide, zirconium oxide, titanium
oxide, calcium oxide, fireclay, silicon carbide, tungsten, mullite,
dolomite, magnesite, magnesium aluminum oxide, chromite, magnetite,
or a combination comprising at least one of the foregoing; and
sintering the blend, wherein the precursor material and/or the
precursor of the protective material is in elemental or compound
form and comprises an element not comprised in the refractory
material selected from the group consisting of silicon, rare earth
elements, zirconium, titanium, yttrium, magnesium, iron, and blends
thereof.
[0009] The various embodiments are relatively inexpensive and
provide protection to refractory materials from the penetration of
slag and extend the service life of refractory material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows an XRF Si map of the slag penetration of an
untreated brick and treated brick described in Example 1.
[0011] FIG. 2 shows an XRF Fe map of the slag penetration of an
untreated brick and treated brick described in Example 1.
[0012] FIG. 3 shows an XRF Si map of the slag penetration of an
untreated brick and treated bricks described in Examples 2-5.
[0013] FIG. 4 shows the cross sections of the untreated and treated
bricks described in Example 6.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Described herein are refractory materials and more
particularly, treated refractory materials including protective
materials configured to minimize slag penetration. In one
embodiment, a treated refractory body comprises a refractory
material having a plurality of pores and a protective material
disposed within the plurality of pores of the refractory material.
As used herein, "refractory material" is generally intended to
refer to any suitable material for us in high temperature (e.g.,
greater than 500 degrees Celsius) systems, such as slagging
gasification. Exemplary refractory materials will have chemical and
physical properties that make them stable and able to retain
strength as structures or components of systems that are exposed to
the high temperatures. The refractory materials, therefore, are
resistant to thermal shock, chemically stable in the slag and
process environment, wear resistant, with high temperature
strength, and thermal conductivities and coefficients of thermal
expansion suitable for use in the high temperature systems. The
refractory materials are further porous and have a connected pore
structure, which includes open pores and closed pores. The pores
can range in size from about 1 micrometer (.mu.m) to about 200
.mu.m in diameter. In an exemplary embodiment, the refractory
material can comprise any type of material suitable for a gasifier
lining. Exemplary refractory materials include, without limitation,
aluminum oxide, silicon oxide, magnesium oxide, chromium oxide,
zirconium oxide, titanium oxide, calcium oxide, fireclay, silicon
carbide, tungsten, mullite, dolomite, magnesite, spinel (magnesium
aluminum oxide), chromite, magnetite, or a combination comprising
at least one of the foregoing.
[0015] The refractory material can be formed into a structure
(i.e., body) suitable for high temperature systems, such as
slagging gasification. In one embodiment, the refractory body can
have a preformed shape. A preformed refractory body is a refractory
material that has been formed (e.g., pre-cast) into a desired shape
and sintered. Exemplary refractory preforms can include, without
limitation, bricks, blocks, tiles, and the like. In another
embodiment, the refractory material is a non-preformed, loose
material which can be formed into complex shapes, or disposed
(e.g., sprayed) into a desired place, and are then sintered before
use in the high temperature system. In still another embodiment,
the refractory material can be sintered in situ. Some
non-preformed, un-fired refractory materials are referred to as
"monolithics". Exemplary monolithics can include, without
limitation, castables, moldables, ramming mixes, gunning mixes,
mortars, refractory plastics, combinations thereof, and the like.
In one embodiment, the refractory body can form the lining of a
slagging gasifier. The lining can be formed from pre-cast bricks,
blocks, or tiles, or it can be formed of refractory monolithics. In
another embodiment, the lining can comprise both pre-formed and
monolithic portions of refractory materials.
[0016] The refractory material can be sintered by firing or heat
treating the material to a temperature of at least about 1000
degrees Celsius (.degree. C.). In one embodiment, the refractory
material can be fired at a temperature from about 1000.degree. C.
to about 1800.degree. C. The refractory material can be fired for a
time suitable to sinter the material, and can depend on such
factors as the material composition, the desired refractory
structure, the desired use, and the like. In one embodiment, the
refractory material can be fired for at least about 1 hour. In
another embodiment, the refractory material can be fired from about
1 hour to about 160 hours; specifically about 1 hour to about 5
hours. The refractory material can be sintered in oxidizing,
reducing, or neutral environments. For example the refractory
material can be sintered in air or in a nitrogen or argon
environment.
[0017] In one embodiment, the refractory material comprises
chromium oxide. In another embodiment, the refractory material
comprises greater than or equal to 40 percent by weight chromium
oxide. In another embodiment, the refractory material comprises at
least 60 percent by weight chromium oxide.
[0018] In another embodiment, the refractory material comprises
chromium oxide and aluminum oxide. The refractory material may
comprise from about 40 to about 95 percent by weight chromium oxide
and from about 5 to about 60 percent by weight aluminum oxide,
based on the weight of the refractory material. In one embodiment,
the refractory material comprises from about 60 to about 95 percent
by weight chromium oxide and from about 5 to about 40 percent by
weight aluminum oxide, based on the weight of the refractory
material.
[0019] In another embodiment, the refractory material comprises
chromium oxide, aluminum oxide and zirconium oxide. The refractory
material may comprise from about 40 to about 90 percent by weight
chromium oxide, from about 5 to about 10 percent by weight
zirconium oxide and from about 5 to about 55 percent by weight
aluminum oxide, based on the weight of the refractory material. In
one embodiment, the refractory material comprises from about 60 to
about 90 percent by weight chromium oxide, from about 5 to about 10
percent by weight zirconium oxide and from about 5 to about 35
percent by weight aluminum oxide, based on the weight of the
refractory material.
[0020] In still another embodiment, the refractory material
comprises chromium oxide and magnesium oxide. The refractory
material may comprise from about 40 to about 90 percent by weight
chromium oxide, from about 5 to about 60 percent by weight
magnesium oxide and/or from about 5 to about 40 percent by weight
aluminum oxide, based on the weight of the refractory material. In
another embodiment, the refractory material is a spinel based
mixture comprising from about 5 to about 70 percent by weight
magnesium oxide, and from about 5 to about 70 percent by weight
aluminum oxide, based on the weight of the refractory material.
[0021] The refractory materials further comprise one or more
protective materials disposed within the pores of the refractory
material. Exemplary protective materials can be selected from the
group consisting of aluminum oxide, chromium oxide, silica, rare
earth oxides, rare earth zirconates, titanium oxide, mullite,
zirconium oxide, zirconium silicate, yttrium oxide, magnesium
oxide, iron oxide, and blends thereof.
[0022] The protective materials are chemically compatible with the
refractory materials and will not decompose in typical gasifier
operating atmospheres of up to about 30 to about 60 atm and at
typical gasifier operating temperatures of up to about 1300 to
about 1600.degree. C. Exemplary protective materials are any type
of material that impedes the infiltration of slag into the
refractory material, such as, for example, by decreasing the
porosity of the refractory material and producing a complex
reaction between the slag and protective material to lower the
slag's effective viscosity. As explained above, liquid slag is a
low viscosity blend of inorganic oxides that is produced as a
by-product in a slagging coal gasifier when the coal or coke is
partially oxidized. The slag may contain silica, aluminum oxide,
calcium oxide and iron oxide. The slag can infiltrate the pores in
the refractory material and degrade the refractory material.
[0023] In one embodiment, the protective material comprises
material that at least partially fills the pores in the refractory
material to prevent the slag from infiltrating the refractory
material and/or material that reacts with the infiltrating slag to
modify the viscosity or wetting behavior of the slag or to decrease
the amount of liquid phase in the slag. In one embodiment, the
protective material is selected from the group consisting of
aluminum oxide, chromium oxide, silica, rare earth oxides, rare
earth zirconates, titanium oxide, mullite, zirconium oxide,
zirconium silicate, yttrium oxide, magnesium oxide, iron oxide, and
blends thereof.
[0024] Precursor compounds may be added to the refractory material.
Precursor compounds react or decompose to form a metal oxide, metal
silicate or metal zirconate. In one embodiment, the precursor
compound is in elemental or compound form and comprises an element
selected from the group consisting of silicon, rare earth metals,
zirconium, titanium, yttrium, magnesium, iron, and blends thereof.
In another embodiment, the precursor compounds may be salts of
metals to transform into metal oxides, metal silicates or metal
zirconates. In another embodiment, salts of the metal compounds
include nitrates, acetates, hydroxides, or carbonates. For example,
the precursor compounds may be aluminum nitrate, chromium nitrate,
silicon nitrate, rare earth nitrates, titanium nitrate, zirconium
nitrate, yttrium nitrate, magnesium nitrate, iron nitrate, or
blends thereof. In another embodiment, the precursor compounds may
be chromium acetate, silicon acetate, rare earth acetates,
zirconium acetate, yttrium acetate, or blends thereof.
[0025] Rare earth metals are elements from the lanthanide series,
such as lanthanum, cerium, praseodymium, neodymium, promethium,
samarium, europium, gadolinium, terbium, dysprosium, holmium,
erbium, thulium, ytterbium, lutetium and mixtures thereof. The rare
earth oxides are oxides of elements from the lanthanide series,
such as lanthanum, cerium, praseodymium, neodymium, promethium,
samarium, europium, gadolinium, terbium, dysprosium, holmium,
erbium, thulium, ytterbium and lutetium. In one embodiment, the
rare earth oxide is cerium oxide. In another embodiment, the rare
earth oxides may be a mixture or alloy of rare earth oxides.
[0026] Rare earth zirconates are zirconates that have a formula of
RE2Zr2O7, where RE is a rare earth element from the lanthanide
series, such as lanthanum, cerium, praseodymium, neodymium,
promethium, samarium, europium, gadolinium, terbium, dysprosium,
holmium, erbium, thulium, ytterbium and lutetium. In one
embodiment, the rare earth zirconate is cerium zirconate,
gadolinium zirconate, lanthanum zirconate or neodymium
zirconate.
[0027] The protective materials may comprise blends. In one
embodiment, the protective material may comprise a blend of
aluminum oxide and silica. In another embodiment, the protective
material may comprise a blend of magnesium oxide and iron oxide. In
another embodiment, the protective material may comprise a blend of
aluminum oxide, chromium oxide, iron oxide and magnesium oxide.
When blends of protective materials are employed, the compounds may
be added to the refractory material together or separately.
[0028] The amounts of each component in the blend may be in any
amount from 0 to 100 percent by weight based on the weight of the
blend. For example, in one embodiment the blend of aluminum oxide
and silica comprises from about 10 to about 90 percent by weight of
aluminum oxide and from about 10 to about 90 percent by weight
silica based on the weight of the blend. In another embodiment, the
blend of aluminum oxide and silica comprises from about 20 to about
80 percent by weight of aluminum oxide and from about 20 to about
80 percent by weight silica, based on the weight of the blend. In
another embodiment, the blend of aluminum oxide and silica
comprises from about 40 to about 60 percent by weight of aluminum
oxide and from about 40 to about 60 percent by weight silica, based
on the weight of the blend.
[0029] The magnesium oxide and iron oxide combination comprises
from about 10 to about 90 percent by weight magnesium oxide and
from about 10 to about 90 percent by weight iron oxide, based on
the weight of the combination. In another embodiment, the magnesium
oxide and iron oxide combination comprises from about 30 to about
70 percent by weight magnesium oxide and from about 30 to about 70
percent by weight iron oxide, based on the weight of the
combination. In another embodiment, the magnesium oxide and iron
oxide combination comprises from about 40 to about 60 percent by
weight magnesium oxide and from about 40 to about 60 percent by
weight iron oxide, based on the weight of the combination.
[0030] In one embodiment, the blend of aluminum oxide, chromium
oxide, iron oxide and magnesium oxide comprises from about 1 to
about 50 percent by weight aluminum oxide, from about 1 to about 50
percent by weight chromium oxide, from about 1 to about 50 percent
by weight iron oxide and from about 1 to about 50 percent by weight
magnesium oxide, based on the weight of the blend.
[0031] The protective material may be added to the pores of the
porous refractory material by infiltrating the protective material
into the refractory material and dispersing the material into the
pores. The protective material infiltrates the refractory material
by any method known in the art, such as painting, spraying,
dipping, coating or vacuum infiltration. In one embodiment, the
protective material infiltrates the refractory material as a
suspension, slurry or liquid solution. The protective material may
be a precursor compound, such as a salt, and is dispersed in a
solvent, such as water, an alcohol or other type of solvent. In one
embodiment, the precursor material may be a nitrate or acetate
salt. In another embodiment, the precursor may be a rare earth
metal and dissolved in acid to form a solution. The suspension,
slurry, liquid solution, or molten salt penetrates into the
refractory material depositing the protective material throughout
the pores of the porous refractory material. The refractory
material is heat treated to evaporate or decompose the solvent and
transform the precursor into the protective material leaving the
protective material situated throughout the open pores of the
refractory material. For example, chromium nitrate or aluminum
nitrate is infiltrated into the refractory material and heat
treated to leave chromium oxide or aluminum oxide situated in the
pores of the refractory material. The heat treatment to evaporate
or decompose the solvent and transform the precursor into the
protective material is at a temperature in a range of from about
100.degree. C. to about 1500.degree. C. from about 1 hour to about
10 hours. In another embodiment, the heat treatment is at a
temperature in a range of from about 300.degree. C. to about
500.degree. C. from about 1 to about 5 hours.
[0032] The protective material may infiltrate the refractory
material in the form of a powder. The powder may comprise
micron-sized or nano-sized particles. In one embodiment, the
particle sizes range from about 5 nanometers (nm) to about 200
.mu.m. In another embodiment, the particle sizes range from about 5
nm to about 100 .mu.m. In another embodiment, the powder comprises
particles ranging in size from about 1 .mu.m to about 10 .mu.m. In
another embodiment, the particle sizes range from about 1 .mu.m to
about 2 .mu.m. In one embodiment, the protective material comprises
nano-sized particles. In one embodiment, the protective material
comprises particle sizes from about 5 nm to about 100 nm. In
another embodiment, the protective material comprises a particle
size from about 5 nm to about 10 nm. Nano-sized powders are
infiltrated as colloid solutions with typical solid loadings of
about 10 to about 50 percent by weight. The colloid solution may be
an aqueous suspension and may contain surfactants to aid in
dispersing the particles.
[0033] In another embodiment, the protective material is dispersed
by vacuum infiltration. For example, an existing preformed
refractory body, such as a sintered brick or an as-fabricated
brick, can be placed under vacuum. A solution or suspension of the
protective material is admitted to penetrate the pores of the
refractory material of the refractory body and the vacuum is
released. In an alternative embodiment, the refractory body can
first be immersed in the suspension or solution and a vacuum
applied. The solution or suspension infiltrates the refractory
material as the vacuum is applied. Air pressure may assist to
produce further infiltration. In a further embodiment, the solution
or suspension is admitted into the material by infiltration at
atmospheric pressure.
[0034] In one embodiment, the amount of protective material
comprises from about 2 to about 20 percent by volume based on the
total volume of the refractory material. The protective material
infiltrates the refractory material to partially fill the pores of
the refractory material. In one embodiment, the protective material
fills from about 3 percent to about 60 percent of the pore volume.
In another embodiment, the protective material infiltrates the
refractive material to fill from about 20 percent to about 50
percent of the pore volume. In one embodiment, the protective
material at least partially coats the inner surfaces of the pores
and forms a sacrificial barrier within the pores to inhibit the
penetration of liquid slag into the refractory material.
[0035] The refractory material may be treated with the protective
material before or after the refractory material has been assembled
into a gasifier. In one embodiment, the protective material is
applied as a final coating to the refractory material lining the
walls of the gasifier. The treated refractory brick retains the
mechanical and physical properties of the as-fabricated brick.
[0036] The treated refractory material minimizes the penetration of
liquid slag into the refractory material. In one embodiment, as the
slag begins to penetrate the surface pores of the refractory
material, the liquid slag encounters the protective materials
disposed within the pores. The liquid slag reacts with the
protective materials to create either a high-melting phase or
phases or a high-viscosity liquid. In either case, further
penetration of the liquid slag is suppressed. Creation of a
high-melting phase or phases reduces the volume of liquid phase and
minimizes slag penetration into the refractory material. Increasing
the viscosity also inhibits penetration of the liquid slag deeper
into the refractory material. For example, in one embodiment,
aluminum oxide is disposed within pores of the refractory material.
When the infiltrating slag contacts the aluminum oxide, the
slag/oxide reaction precipitates higher-melting phases, such as
anorthite, and reduces the volume of liquid phase available for
penetration into the refractory material.
[0037] In another embodiment, when fine particles of silica are
disposed within pores of the refractory material, the slag will
become enriched in silica. The addition of silica increases the
viscosity of the liquid slag. Such an increased viscosity inhibits
slag penetration into the refractory material.
[0038] A combination of approaches can be used to both increase the
viscosity and raise the melting temperature of the liquid slag. In
one embodiment, the protective infiltrant is a blend of aluminum
oxide and silica. The aluminum oxide causes precipitation of
higher-melting phases and the silica increases the viscosity of the
remaining liquid slag.
[0039] In another embodiment, the protective material minimizes the
penetration of the slag into the refractory material by filling
openings between grains of the refractory material. For example,
chromium oxide is resistant to dissolution in slag, but reduces the
permeability of the refractory material by filling channels between
grains with relatively inert material.
[0040] In another embodiment, a process for making a treated
refractory body comprises adding one or more protective materials
to an existing refractory body, wherein the protective materials
enter the pores of porous sintered refractory material of the
refractory body, wherein the protective material is selected from
the group consisting of aluminum oxide, chromium oxide, silica,
rare earth oxides, rare earth zirconates, titanium oxide, mullite,
zirconium oxide, zirconium silicate, yttrium oxide, magnesium
oxide, iron oxide, and blends thereof.
[0041] As explained above, the protective material is added to the
refractory material by infiltrating the protective material into
the refractory material and dispersing the material into the pores.
The protective material infiltrates the refractory material by any
method known in the art, such as painting, spraying, dipping,
coating or vacuum infiltration. The protective material may be a
precursor compound, such as a salt, and is dispersed in a solvent,
such as water, an alcohol or other type of solvent. In one
embodiment, the precursor material may be a nitrate or acetate
salt. In another embodiment, the precursor material may be a metal,
dissolved in acid to form a solution.
[0042] In another embodiment, a process for making treated
refractory material comprises blending refractory material and one
or more protective materials and sintering the blend, wherein the
protective material is selected from the group consisting of
silica, rare earth oxides, rare earth zirconates, titanium oxide,
mullite, zirconium silicate, yttrium oxide, magnesium oxide, iron
oxide, and blends thereof.
[0043] In another embodiment, a process for making treated
refractory material comprises blending the refractory material and
a protective material and/or a precursor of a protective material
and sintering the blend, wherein the protective material and/or the
precursor material is in elemental or compound form and comprises
an element selected from the group consisting of silicon, rare
earth elements, zirconium, titanium, yttrium, magnesium, iron, and
blends thereof.
[0044] As explained above, precursor compounds react or decompose
to form a metal oxide, metal silicate or metal zirconate. In one
embodiment, the precursor compounds may be salts that can be
transformed into the metal oxides, metal silicates or metal
zirconates upon heat treatment. In another embodiment, salts of the
metal compounds include nitrates and acetates.
[0045] The protective material is blended with the refractory
material in any amount that is suitable for treating the refractory
material. In one embodiment, the protective material is added in
amount of from about 1 to about 10 percent by weight based on the
weight of the blend. In another embodiment, the protective material
is added in amount of from about 5 to about 10 percent by weight
based on the weight of the blend.
[0046] The blend of refractory material and protective material may
be formed into any desired shape. In one embodiment, the refractory
material is formed into a pre-cast shape, such as a brick, block,
tile, or the like. In another embodiment, the refractory material
is a monolithic. In still another embodiment, the refractory
material has both pre-formed and monolithic portions. The blend of
refractory material and protective material is sintered by firing
or heat treating the material to a temperature of at least about
1000.degree. C. In one embodiment, the material is fired at a
temperature from about 1000.degree. C. to about 1800.degree. C. In
one embodiment, the refractory material is fired for at least about
1 hour. In another embodiment, the refractory material is fired
from about 1 hour to about 24 hours. The refractory material may be
sintered in air or in a nitrogen or argon environment.
[0047] The treated refractory materials can impart some measure of
self-healing. If the surface layers of the refractory material are
removed, the underlying protective material disposed within the
refractory material will again react with the slag to reform a
renewed protective layer against further infiltration of slag.
[0048] In order that those skilled in the art will be better able
to practice the present disclosure, the following examples are
given by way of illustration and not by way of limitation.
EXAMPLES
Example 1
[0049] A sintered high chromia (90 wt %) brick was infiltrated with
chromium (III) nitrate solution multiple times followed by
subsequent heat treatments in air at 600.degree. C. for 2 hours to
decompose the nitrate salt into chromium oxide. The weight of the
protective material constituted approximately 10 percent by weight
of the refractory brick after all infiltrations. The infiltrated
brick was then annealed in nitrogen at 1600.degree. C. for 20 hours
to pre-react the chromium oxide before the slag infiltration. The
porosity of the untreated refractory before the slag infiltration
was about 18-20 vol. %. After infiltration and heat treatment, the
porosity was about 12-14 vol. %.
[0050] A slag infiltration test via isothermal annealing of cups
filled with slag was performed on the brick infiltrated with
chromium oxide and on an untreated brick. The slag composition
contained 59.0% silica, 10.7% aluminum oxide, 8.3% calcium oxide,
21.6% iron oxide and 0.3% potassium oxide. Test parameters were
1490.degree. C. for 20 hours at an oxygen partial pressure of 10
-10 atm provided via a mixture of wet and dry N2/3% H2 gas.
[0051] Subsequent analysis of slag penetration by XRF mapping of Si
and Fe distribution at the brick cross-section revealed that slag
penetration in the treated brick is much less than the slag
penetration into the untreated brick. FIG. 1 shows an XRF mapping
of Si of the slag penetration of the untreated sintered brick and
the treated brick. FIG. 2 shows an XRF mapping of Fe of the slag
penetration of the untreated brick and the treated brick.
Example 2
[0052] Example 1 was reproduced with the exception of using
chromium (III) acetate (Cr3(OH)3(CH3COO)2 as the precursor to the
chromium oxide protective material. A slag infiltration test via
isothermal annealing of cups filled with slag was performed on the
brick infiltrated with chromium oxide and on an untreated brick.
Test parameters were 1500.degree. C. for 20 hours at an oxygen
partial pressure of 10 -10 atm provided via a mixture of wet and
dry N2/3% H2 gas.
[0053] Subsequent analysis of slag penetration by XRF mapping of Si
distribution at the brick cross-section revealed that slag
penetration in the treated brick is much less than the slag
penetration in the untreated brick. FIG. 3A shows an XRF mapping of
Si of the slag penetration of the untreated brick and the brick
treated with chromium oxide.
Example 3
[0054] Example 1 was reproduced with the exception of using
aluminum nitrate as the precursor for the aluminum oxide protective
material. A slag infiltration test via isothermal annealing of cups
filled with slag was performed on the brick infiltrated with
aluminum oxide and on an untreated brick. Test parameters were
1500.degree. C. for 20 hours at an oxygen partial pressure of 10
-10 atm provided via a mixture of wet and dry N2/3% H2 gas.
[0055] Subsequent analysis of slag penetration by XRF mapping of Si
distribution at the brick cross-section revealed that slag
penetration in the treated brick is much less than the slag
penetration in the untreated baseline brick. FIG. 3B shows an XRF
mapping of Si of the slag penetration of the untreated brick and
the brick treated with aluminum oxide.
Example 4
[0056] Example 1 was reproduced with the exception of using cerium
nitrate as the precursor for the cerium oxide protective material.
A slag infiltration test via isothermal annealing of cups filled
with slag was performed on the brick infiltrated with cerium oxide
and on an untreated baseline brick. Test parameters were
1500.degree. C. for 20 hours at an oxygen partial pressure of 10
-10 atm provided via a mixture of wet and dry N2/3% H2 gas.
[0057] Subsequent analysis of slag penetration by XRF mapping of Si
distribution at the brick cross-section revealed that slag
penetration in the treated brick is much less than the slag
penetration in the untreated brick. FIG. 3C shows an XRF mapping of
Si of the slag penetration of the untreated brick and the brick
treated with cerium oxide.
Example 5
[0058] Example 1 was reproduced with the exception of using
gadolinium nitrate and zirconium nitrate as the precursors for the
gadolinium zirconate protective material. A slag infiltration test
via isothermal annealing cups filled with slag was performed on the
brick infiltrated with gadolinium zirconium oxide and on an
untreated baseline brick. Test parameters were 1500.degree. C. for
20 hours at an oxygen partial pressure of 10 -10 atm provided via a
mixture of wet and dry N2/3% H2 gas.
[0059] Subsequent analysis of slag penetration by XRF mapping of Si
distribution at the brick cross-section revealed that slag
penetration in the treated brick is much less than the slag
penetration in the untreated baseline brick. FIG. 3D shows an XRF
mapping of Si of the slag penetration of the untreated brick and
the brick treated with gadolinium zirconate.
Example 6
[0060] A fused-cast and sintered brick of 75% weight chromia was
vacuum infiltrated multiple times with a colloidal suspension of
nano-scale particles of Al2O3 having particle sizes of about 50 nm.
After each infiltration, the brick was heated to 800.degree. C. for
4 hours in air to decompose the dispersant. The same refractory
brick was subsequently vacuum infiltrated multiple times with a
colloidal suspension of nano-scale particles of SiO2 having
particle sizes of about 12 nm. Between each of the SiO2
infiltrations the brick was heated to 120.degree. C. for 2 hours to
remove water.
[0061] A slag infiltration test via isothermal annealing of cups
filled with slag was performed on the brick infiltrated with
aluminum oxide and silica. The slag infiltration test was also
performed on an untreated brick. Test parameters were 1500.degree.
C. for 20 hours at an oxygen partial pressure of 10 -10 atm
provided via a mixture of wet and dry N2/3% H2 gas.
[0062] The treated brick clearly shows reduced slag infiltration
from 15 mm to 3 mm slag-penetration when compared with the
untreated brick at the brick cross-section. The cross sections of
the untreated brick and the treated brick at an oxygen partial
pressure of 10 -10 atm provided via a mixture of wet and dry N2/3%
H2 gas are shown in FIG. 4. The treated brick clearly shows reduced
slag infiltration from 15 mm to 3 mm 15 slag penetration when
compared with the untreated brick at the brick cross-section. The
cross sections of the untreated brick and the treated brick are
shown in FIG. 4.
[0063] As used herein, the oxidation state of the elements used can
vary. The mention of the oxide of any element in one oxidation
state includes oxides of this element in all existing oxidation
states. For instance, cerium oxide includes Ce.sub.2O.sub.3 and
CeO.sub.2, iron oxide includes FeO and Fe.sub.2O.sub.3 and chromium
oxide includes Cr.sub.2O.sub.3 and CrO.
[0064] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. Ranges disclosed herein are inclusive and combinable
(e.g., ranges of "up to about 25 wt %, or, more specifically, about
5 wt % to about 20 wt %", is inclusive of the endpoints and all
intermediate values of the ranges of "about 5 wt % to about 25 wt
%," etc.). "Combination" is inclusive of blends, mixtures, alloys,
reaction products, and the like. Furthermore, the terms "first,"
"second," and the like, herein do not denote any order, quantity,
or importance, but rather are used to distinguish one element from
another, and the terms "a" and "an" herein do not denote a
limitation of quantity, but rather denote the presence of at least
one of the referenced item. The modifier "about" used in connection
with a quantity is inclusive of the stated value and has the
meaning dictated by context, (e.g., includes the degree of error
associated with measurement of the particular quantity). The suffix
"(s)" as used herein is intended to include both the singular and
the plural of the term that it modifies, thereby including one or
more of that term (e.g., the colorant(s) includes one or more
colorants). Reference throughout the specification to "one
embodiment", "another embodiment", "an embodiment", and so forth,
means that a particular element (e.g., feature, structure, and/or
characteristic) described in connection with the embodiment is
included in at least one embodiment described herein, and may or
may not be present in other embodiments. In addition, it is to be
understood that the described elements may be combined in any
suitable manner in the various embodiments.
[0065] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which the
embodiments of the invention belong. It will be further understood
that terms, such as those defined in commonly used dictionaries,
should be interpreted as having a meaning that is consistent with
their meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0066] While the disclosure has been described with reference to an
exemplary embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the disclosure. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
disclosure without departing from the essential scope thereof.
Therefore, it is intended that the disclosure not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this disclosure, but that the disclosure will include
all embodiments falling within the scope of the appended
claims.
* * * * *