Note: Descriptions are shown in the official language in which they were submitted.
5.
~ WO 95121019 PCT/US95101374
1
MATERIAL FOR REMOVING CONTAMINANTS FROM GASEOUS STREAM
BACKGROUND OF THE INV.umrnu _
Field of the Invention
,
r
The present invention relates to a process for reducing
gaseous pollutants in the air, namely nitrogen oxides
(NOX), sulfur oxides and/or carbon monoxide (CO), which are
produced by combustion of hydrocarbons or hydrogen in an
engine or boiler, and primarily, in a gas turbine. The
present invention is also directed to an apparatus for
performing the process and a process for making the
reactor/catalyst absorber.
Art Background
Turbine power plants are becoming the standard for
generating electricity because they are so efficient
compared to any other form of power manufacture. Turbine
power plants that burn methane to produce power for
residents and manufacturing facilities in cities also
produce carbon monoxide and nitrogen oxide as pollutants.
It is highly desirable to reduce or eliminate these
pollutants so that the air is not contaminated as a result
of power production.
Initially, the permitted level of pollution by power
plants for nitrogen oxides (NOx), which includes nitric
oxide (NO) and nitrogen dioxide (N02), was less than 100
parts-per-million (ppm) and the level of carbon monoxide
(CO) was to a level of less than 100 ppm. Later, a second
step was taken to reduce the NOx to less than 25 ppm and
the CO today is still permitted at any amount less than 100
ppm. Using current technology, the output levels of NOx
can be reduced to the range of 5 to 9 ppm plus NH3 slippage
resulting from the selective catalytic reduction (SCR)
technology described below.
The only technology which is currently available to
obtain the 5-9 ppm NOx levels is called selective catalytic
reduction, in which ammonia is mixed with flue gas and then
passed over a catalyst which selectively combines the
nitrogen oxides and ammonia to eliminate a major portion
of the NOx. One problem with the selective catalytic
WO 95121019 ~ PCflUS9510137.t
2
reduction is that as a practical matter, it is only
capable of reducing the NOx to the range of 5 to 9 ppm.
Another problem referred to as slippage, is caused by ,
hazardous ammonia passing through the catalyst.
Another problem of the SCR technology is that the
operating conditions required for SCR are only achieved by
expensive modifications of the down stream boiler or heat
exchanger system.
There have been other technologies for reduction of
pollution which have been advanced, such as overwatering in
the combustor, and these also have the potential to reduce
the NOx pollution, but none of them reduce the NOx to
levels much less than 5 to 9 ppm.
In a copending application owned by the assignee of the
present application, a system comprising essentially a two
step process has been described. In the first step, the
stack gases are first contacted with a catalyst under
certain conditions which cause the oxidation of certain
oxide pollutants, including NO and CO. In the second step,
the oxidised pollutants are absorbed in an absorption bed.
It would be desirable to combine the oxidation and
absorption steps into a single step performed by a single
material.
SUMMARY OF THE INVENTION
The present invention has the capability of reducing
hydrocarbon burning engine waste pollutants, and
particularly those from a gas turbine, including nitrogen
oxide, carbon monoxide and sulfur oxides. The invention,
as described in more detail below, includes a novel
catalytic absorber and method of making the absorber, a
novel process and apparatus capable of reducing air
pollutants and 'the method of making the apparatus.
The pollutants from a turbine in a power generating
stack are primarily present as NO. The process of the
present invention causes oxidation of the NO to N02. This
produces N02 from substantially all of the nitrogen oxides
(NO). N02 is a much more active material and can be and is
absorbed readily by the catalytic absorber from the gas
. WO 95121019 PCTIUS95I0137.1
'.
3
stream even when present at low concentrations in the ppm
range.
The turbine exhaust gases are initially at about 1000F
after the shaft energy has been withdrawn from them. These
gases are then passed over heat exchangers to remove energy
and produce steam while cooling the exhaust or stack gases.
Stack.gases are moving at high velocity depending upon the
diameter of the stack, and after heat is removed, the stack
gases typically are in the range of 250 to 500'F and travel
about 30-50 feet per second. The gas contains 13-15%
oxygen, up to about 12% water, and about 4% carbon
dioxide.' This in addition to the pollutants, which are
the NOx mixed with approximately 90% NO and 10% N02, CO in
the range of 30 to 200 ppm and sulfur dioxide (S02) in the
range of about 0.2 to 2.0 ppm when natural gas is the fuel.
The present invention involves a one step/one element
process and apparatus to remove the nitrogen oxides, carbon
monoxide, and sulfur oxides from the stack gases. Using a
combined catalyst/absorber, the nitrogen oxides are
oxidized to nitrogen dioxide; the carbon monoxides are
oxidized to carbon dioxide, and the sulfur dioxide (SO2) is
oxidized to sulfur trioxide (S03). This oxidation occurs
' at temperatures in the range of 150 to about 425'F, and
more preferably in the range of 175 to 400F, and most
preferably in the range of 200 to 365'F. The space
velocity of the exhaust gas may be in the range of 5, 000
to 50,000 per hour (hr'1) and more preferably in the range
of 10,000 to 20,000 hr 1, although it is anticipated that a
larger range will permit effective operation without an
undue reduction in quality of the output gas. As used
herein, the term space velocity means volume units of flow
per volume units of catalyst per hour.
The catalyst absorber of the present invention absorbs
the oxidized oxides so that only a small percentage,
generally 10% or less of the initial oxide pollutants,
pass through the system and are released. While not being
bound to a particular theory, it is presently believed that
the reactions which occur are as follows for each of the
WO 95121019 PCT/US95/0137.1
~~.~1~~~
r'
~1 v
1 .1
three pollutants, with an oxidation occurring, followed by
a reaction with the carbonate such as Na2C03:
Catalyst
CO + 1/2 OZ ---~ C02
C02 + Hz0 + Na2C03 ---~ 2NaHC03
Catalyst
No + 1/a o2 ---. No2
2N02 + Na2C03 ---~ NaN03 + NaN02 + COa
Catalyst
SOZ + 1/2 OZ ---~ S03
S03 + Na2C03 ---~ Na2S04 + C02
SOZ + NaaC03 ---~ Na2SOg + COZ
The catalyst/absorber may be a platinum catalyst
supported on alumina with an alkali or alkaline earth
carbonate or bicarbonate coating thereon, the carbonate
coating being lithium, sodium, potassium or calcium
carbonate, and presently the preferred coating is a
potassium carbonate.
The absorber, when it ceases to be effective, and
specifically, when the level of pollutants emanating from
the apparatus after contact with the catalyst absorber
increases beyond an acceptable level, can be replaced, and
the used absorber can be recharged to an effective status
again. Recharging of the catalyst is accomplished by
removing the spent (saturated or partially saturated
carbonate and replacing the spent carbonate with fresh
unreacted carbonate.
BFIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic depiction of the catalyst
absorber of the present invention.
Figure la is a drawing of a catalyst absorber sphere in
a preferred embodiment.
Figure 1b is a magnified drawing of a portion of the
surface of the catalyst absorber sphere of the present
invention.
Figure 1c is a drawing of the surface of a monolith
catalyst absorber of the present invention.
Figure 2 is a flowchart showing the process of making
. W095/21019 ~ , PCTIUS95/0137.t
the catalyst of the present invention.
Figure 3 is an illustration of a wheel apparatus for
changing and regenerating the oxidation catalyst/absorber
of the present invention.
5 Figure 4 is an illustration of a carousel apparatus for
changing and regenerating the oxidation catalyst/absorber
of the present invention.
Figure 5 is an illustration of a fluidized bed apparatus
for changing and regenerating the oxidation
catalyst/absorber of the present invention.
Figure 6 is an illustration of a multiple fluidized bed
apparatus for changing and regenerating the oxidation
catalyst/absorber of the present invention.
DETATLED DESCRIPTION OF THE T~'NTTfIN
The present invention is directed to a material for
removing gaseous pollutants from combustion exhaust
streams, in which the material comprises an oxidation
catalyst specie disposed on a high surface area support
coated with an absorber material. The oxidation catalyst
specie is selected from the group of noble metal elements,
base metal transitional elements and combinations thereof.
More particularly, the oxidation catalyst species are
selected from platinum, palladium, rhodium, cobalt, nickel,
iron, copper and molybdenum, and preferably, platinum and
rhodium, and most preferably, platinum.
The oxidation catalyst specie concentration is 0.05 to
0.6 percent by weight of the material, and preferably is
0.1 of 0.4 percent by weight of the material, and most
preferably is 0.15 to 0.3 percent by weight of the
material. More than one element may be used as an
oxidation catalyst specie, and under these conditions each
of said elements has a concentration in the range of 0.05
to 0.6 percent by weight.
The high surface area support is made of alumina,
zirconia, titania, silica or a combination of two or more
of these oxides. Preferably, the high surface area support
is made of alumina. The surface area of the support is in
the range of 5o to 35o square meters per gram, preferably
WO 95121019 PCTICTS95l0137;
~~8Z33'~
6
100 to 325 square meters per gram, and more preferably 200
to 300 square meters per gram. The high surface area
support may be coated on a ceramic or metal matrix
structure.
The catalyst absorber may be in a shape such as a ~
sphere, solid cylinder, hollow cylinder, star shape or
wheel. shape.
The absorber is coated with at least one alkali or
alkaline earth compound, which can be hydroxide compound,
bicarbonate compound, or carbonate compound, or mixtures of
hydroxides and/or bicarbonates and/or carbonated compounds.
Preferably, the absorber comprises substantially all
carbonate, and most preferably sodium carbonate, potassium
carbonate or calcium carbonate. The absorber is disposed
on the material. at a concentration in the range of 0.5 to
percent by weight of the material, preferably 5.0 to 15
percent by weight of the material, and most preferably
about l0% percent by weight of the material.
The process for making the novel catalyst absorber of
20 the present invention includes applying the oxidation
catalyst specie from solution. The solution is preferably
a nonaqueous solution. The oxidation catalyst specie may
also be applied from chloride free aqueous solution. Once
applied the oxidation catalyst specie is dried after
application and may be activated after application,
possibly by calcining it.
After the catalyst absorber is spent or partially spent,
it can be reactivated. Reactivation is accomplished by
removing and replacing the spent absorber and disposing of
the removed spent absorber. The spent absorber can be used
as fertilizer in that it is rich in nitrogen, carbon and
sulfur. Alternatively, reactivation is accomplished by
decomposing components formed by the combination of
pollutants with the absorber and trapping the concentrated
pollution gases for disposal or use. The apparatus of the
present invention supports the catalyst absorber and
contacts the catalyst absorber with a combustion exhaust.
It includes a means for removing spent catalyst absorber
. WO 95/21019 ~ 1 8 1 3 3 7 pCf/U595/0137.t
7
from contact with the combustion gases and at the same time
moving an equivalent amount of new or regenerated catalyst
absorber into contact with the combustion gas to maintain a
specified outlet pollution concentration limit. The
apparatus is in the shape of a wheel or carousel, or it
may be a fluid bed or two or more beds which are
alternately used for absorption of pollutant gases and
reactivated.
As shown in Figure 1, the catalyst absorber of the
present invention can take on different configurations.
Figure la shows a spherical catalyst absorber made up of an
alumina sphere l0 with a platinum coating 12 and a
carbonate coating 14 thereon. As shown in Figure 1b, the
surface of the sphere is very irregular so that there is an
extremely large surface area per gram of material as
described herein. As shown in Figure lc, the catalyst
absorber can be in the form of a monolith surface including
a ceramic or stainless steel support 20, an alumina layer
22, a platinum layer 24 and a carbonate layer 26.
The method of making the catalyst absorber is shown in
Figure 2. The catalyst/absorber of the present invention
is made by starting with high surface area alumina spheres
having a surface area of 50 to 350 squares per gram, these
spheres being commercially available from several sources,
and preferably from La Roche Chemicals, Inc., Baton Rouge,
La. The spheres are approximately 1/8 inch in diameter.
It will be appreciated that other forms of supports may be
used without departing form the spirit and scope of the
present invention. The alumina spheres are washed with
distilled water to remove small particles bound loosely to
the surface. The spheres are then dried for about 16 hours
at 300°F to ensure that all of the cavities and interstices
in the spheres are fully dried, and that the surface is
free of water. The spheres are then stored in an air-tight
container until ready for further processing.
A solution of Pt 2-ethylhexanoate which contained 25% Pt
was added to toluene to get a concentration of Pt such that
the weight of solution equal to the toluene uptake would
wo 9siaiois rcr~s9sioia~a
~18~33'l
contain sufficient Pt to give a loading of 0.23 weight
percent per weight of alumina. The platinum coated spheres
were then dried for l hour at 900°F in air. The spheres
are then cooled to approximately room temperature and
stored in an air-tight container again. The platinum
coated spheres are then coated with an alkali or alkaline
earth carbonate or bicarbonate coating, the alkali or
alkaline earth carbonate or bicarbonate being selected from
lithium, sodium, potassium or calcium carbonate or
bicarbonate solution, preferably a sodium carbonate
solution at a concentration of 14 percent by weight in
distilled water. The water was heated to dissolve all of
the sodium carbonate. The carbonate coated spheres were
then dried at 300'F for two hours. The final catalyst
absorber had a coating of platinum in the amount of 0.23
weight percent added to the alumina, and 10.0 weight
percent Na2C03 added to the alumina. The spheres are then
disposed in a 3 x 3 x 6 inch wire mesh basket and used as
described below.
Alternatively, another form of the catalyst absorber can
be made using oeramic or metal monolith supports. Tests
were performed by taking a core plug of a metal monolith
having approximately 300 openings per square inch,
obtaining a core from the monolith of appropriate
dimensions for use in the test equipment, coating the
surface of the channels in the monolith with alumina from a
water slurry, calcining at 900'F for 3 hours, and cooling.
This core is then coated with a platinum coating as
described above with respect to the spheres and then the
carbonate is applied by the method used for the spheres.
After the catalyst absorber is exhausted or saturated,
it can be regenerated. A typical regeneration procedure is
as follows:
1. The beads after cooling are transferred to
containers approximately 7" x 10" x 5". The
containers have closeable lids and inlet and
outlet gas or drain lines.
2. Approximately 260 cubic inches of spheres are
WO 95/21019 2 I 8 ~. 3 3 ~~ PCT~S9510I374
9
washed at 190°F with 4 liters of demineralized
water for five minutes with stirring.
3. Samples are taken as the liquid is drained off.
4. Three liters of approximately 14% sodium or
potassium carbonate solution at 190°F are added to
the container.
5. The spheres are stirred and soaked for 20 minutes,
or as little as 2 to 5 minutes.
6. Samples are taken as solution is drained.
7. In a 300°F furnace the beads are dried for 45
minutes with approximately 10 scfm heated dry air
flowing through the container.
8. The weighed dry beads are returned to the screen
container for reuse.
As shown in Figure 3, the catalyst absorber of the
present invention can be installed in a wheel apparatus to
permit contacting stack gases with the catalyst absorber
and regenerating the catalyst absorber after it is
saturated or partially saturated. As shown in Figure 3,
the wheel apparatus includes an inlet 30 for receiving the
combustion gases and stack 32 for exhausting the treated
gases, a cylindrical assembly 34 containing catalyst
absorber and a regenerating unit 36 for regenerating the
spent catalyst, the regenerating unit having an inlet 37
and outlet 38 for replenishing fresh regeneration fluid.
The inner wall 39 and outer wall 40 of a portion of the
wheel adjacent the stack 32 are perforated or otherwise
vented to permit passage of the gas therethrough. The
inner and/or outer walls 41 and 42 of the remainder of the
3o wheel is closed so that the exhaust gases only exhaust
through the stack 32. A drive 44 is used to rotate the
wheel either discretely or continuously. Arrow A
designates the direction of the drive 44 rotation and arrow
B indicates the direction of the wheel rotation.
As shown in Figure 4, an alternative arrangement for the
catalyst absorber is disclosed, in which a carousel is
used. The stack gases enter through the inlet 50 and exit
through the stack 52. The catalyst absorber is inserted in
W095/ZI019 J , ~. PCT/US95101374
line with the stack gases at 54, and when spent is
retracted into the carousel at 56 and a new absorber
installed. The spent catalyst absorber is then
regenerated. Fresh regeneration fluid enters through inlet
5 57 and is removed through outlet 58.
As shown in Figure 5, a fluidized bed apparatus is
disclosed. This apparatus has a combustion gas inlet 60
and stack outlet 70. There is a fluidized bed 62 in line
with the gas which contains active catalyst absorber. A
10 portion of the catalyst absorber is removed from the
fluidized bed and moved to the regeneration unit 64.
Regeneration fluid is sent into the regenerator at 65 and
is removed by the fluid separator 66.
As shown in Figure 6, a multiple fluidized bed apparatus
is disclosed. This apparatus has a combustion gas inlet 71
and stack outlet 80. There is a first fluidized bed 72 in
line with the gas which contains active catalyst absorber.
There is a second fluidized bed 73 which is being
regenerated. The first fluidized bed has inlet 76 and
outlet 77 with valves to permit regeneration fluid in and
out. The second fluidized bed has inlet 74 and outlet 75
with valves to permit regeneration fluid in and out. Valve
78 controls whether combustion gases go to the first or
second fluidized bed.
In the following examples, gas measurements were made as
follows; CO was measured by a TECO model 48 infrared
analyzer, C02 was measured by a Horiba Co2 infrared meter
and NO and N02 were measured using a TECO model #10R
chemiluminescent detector with a stainless steel converter.
Sulfur oxides were measured using a TECO model #43a Pulsed
Fluorescence S02 Analyzer.
Examples of the performance of the present invention are
set forth below.
Experiment No. 1
In each of the following experiments, the starting gas
was obtained from a slip stream from the turbine exhaust
from a cogeneration plant turbine. The catalyst absorber
was disposed in two wire mesh baskets having a 3 inch by 3
W0 95121019 pCTlUS9510137d
11
inch by 6 inch geometry and placed in line with the slip
stream in series to min imize any edge effects nd ensure
a
that all of the slip with the
stream
comes
in
contact
catalyst absorber . The space velocity of the sl ip stream
was 18,000 hr 1. The o temperatures listed ind icate the
tw
temperature for the upstream firs t basket and the
temperature for the
downstream
second
basket.
all
pollutant measurements are in ppm. NOx is the
total
concentration of nitrogen oxide (NO) nd nitrogen
a dioxide
(N02).
~Tnit-;a~ Starting ollutant Levels
P
CO in. 10.98 ppm
NO in, 29.0 ppm
NOx in, 33.0 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min (F) (F) (PPm) (PPm) (PPm)
:15 230 216 0.36 3.0 3.0
:30 355 323 0.18 3.0 4.0
:45 355 328 0.20 3.0 4.0
1 hr. 354 329 0.19 3.0 5.0
1:15 352 328 0.20 3.0 5.0
1:30 351 328 0.23 2.5 6.0
1:45 350 327 0.25 3.0 7p
2 hrs. 348 325 0.17 7.0 gp
2:15 348 325 0.17 7.0 8.0
2:30 348 325 0.19 8.0 10.0
2:45 348 325 0.18 9.0 10.0
3 hrs. 348 325 0.18 10.0 11.0
3:15 347 325 0.17 11.0 12.0
3:30 346 323 0.17 11.0 12.0
3:45 346 322 0.18 12.0 13.0
Experiment
No.
1-a
The catalyst absorber and the
was
regenerated
experiment was ru n again
under
the
same
conditions
using
the regenerated catalyst absorber.
Tn~tial Startinct ollutant Tevels
P
CO in. 9.91 ppm
NO in, 30.0 ppm
' NOx in, 36.0 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min (F) (F) (ppm) (ppm) (ppm)
:15 135 162 2.49 16.0 16.0
:30 365 160 .13 5.0 5.0
WO 95121019 21 ~3 I 3 3'~ '' a r~ ~ °'' PGT/1T59510137.1
12
:45 363 351 .05 2.0 2.0
1 hr. 363 353 .05 2.5 2.5
1:15 362 353 .08 4.0 4.0
1:30 362 352 .05 4.5 5.0 -
1:45 362 354 .07 5.5 6.0
2 hrs. 362 354 .07 6.0 7.0
2:15 362 354 .07 7.0 8.0
2:30 361 353 .06 7.5 8.5
2:45 362 354 .09 8.5 9.5
3 hrs. 362 354 .08 9.0 10.0
3:15 362 354 .08 9.0 10.5
3:30 363 355 .08 10.0 11.5
3:45 363 356 .08 10.0 12.0
4 hrs. 364 356 .07 10.5 12.5
It is believed that the first reading 15 minutes
at
showed high po7-lution because the temperature
level of the
catalyst the necessary
absorber temperature
was below for
oxidation.
Experiment -b
No. 1
The catalyst absorber regenerated
was a second
time
and
the experiment run aga in unde r the same conditions
was
using absorber.
the twice
regenerated
catalyst
?.~i~t~a~Startncr Pol lutant
Levels
Co in. 13.16 ppm
NO in, 26.0 ppm
NOx in, 32.5 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min (F) ('F) (ppm) (ppm) (ppm)
:15 133 134 0.2 23.0 23.0
:30 296 139 3.02 16.0 16.0
:45 313 142 0.43 7.5 7.5
1 hr. 296 296 0.30 6.0 6.0
1:15 285 285 0.34 7.0 7.0
1:30 279 278 0.37 8.5 8.5
1:45 282 273 0.40 10.0 10.0
2 hrs. 304 290 0.30 9.5 9.5
2:15 320 308 0.25 9.5 10.0
2:30 330 319 0.22 10.0 11.0
2:45 339 329 0.20 10.5 12.0
3 hrs. 343 334 0.20 11.5 12.5
3:15 347 338 0.22 12.0 14.0
Experiment No. 1-c
The catalyst absorber was regenerated again and the
experiment was run again under the same conditions using
the three time regenerated catalyst absorber.
wo9snlo19 Z~'~'~33~ , ,
PCT/US95101374
13
~nii'.i.~1Ctartinn Dnrr"ta..a-......1j
r
CO in. 12.13 ppm
NO in, 28.0 ppm
NOx in,
34.0 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min (F) (PPm) (PPm) (ppm)
('F)
:15 142 155 7.61 20.0 20.0
:30 352 195 0.30 3.0 3.0
:45 350 342 0.22 2.5 2.5
1 hr. 351 342 0.23 3.0 3_5
1:15 351 343 0.24 4.0 4.5
1:30 351 345 0.24 5.0 5.5
1:45 351 344 0.27 6.0 6.5
2 hrs. 352 345 0.24 6.5 7.5
2:15 351 346 0.24 8.0 9.D
2:30 351 345 0.23 g.D g,D
2:45 351 345 0.30 9.0 10.0
3 hrs. 350 343 D.37 9.5 11.0
3:15 350 342 0.28 10.0 12.0
3:30 348 341 0.30 11.0 12.0
3:45 348 341 0.30 12.0 13.5
Experiment
No. 1-d
The catalyst absorber and the
was regenerated
again
experiment
was run
again
under
the same
conditions
using
the four
time regenerated
catalyst
absorber.
Ini ti Starting ~ "+a>,+ ~ 1
a~ r.
CO in. 13.16 ppm
3D NO in, 28.0 ppm
NOx in, 34.0 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min (F) (F) (ppm) (PPm) (PPm)
:15 132 132 10.28 22.0 23.0
:30 353 143 1.22 8.0 g.p
:45 351 259 0.45 4.0 4_5
1 hr. 350 338 0.42 4.0 4.5
1:15 349 338 0.43 5.0 5.5
1:30 349 338 0.41 6.0 6.5
1:45 349 339 0.41 7.0 7.5
2 hrs. 349 339 0.42 8.0 9.p
2:15 348 338 0.46 8.5 g_5
2:30 349 339 0.45 9.5 10.5
2:45 349 339 0.49 10.0 11.5
3 hrs. 349 339 0.48 10.5 12.0
3:15 350- 340 0.55 11.0 13.0
Experiment
No. 2
The conditionsfor this series of experiments was the
same as those for Experiment No. 1. This
series
was begun
WO 95121019 PCT/US9510I37.1
~v
w,
14
with a absor7~er the same type and
new catalyst of
configu ration as scribed Experiment No. 1.
de above
for
initial Starting llutant Levels .
Po
CO in. 10.98 ppm
NO in, 29.0 ppm
NOx in, 33.0 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min ('F) ('F) (ppm) (ppm) (ppm)
:15 345 225 0.20 2.0 2.0
:30 348 308 0.19 2.0 2.5
:45 350 315 0.22 2.0 2.0
1 hr. 350 317 0.24 2.0 2.5
1:15 351 317 0.23 2.5 2.5
1:30 351 318 0.23 3.0 3.0
1:45 351 317 0.24 3.5 4.0
2 hrs. 351 317 0.26 5.0 7.0
2:15 350 318 0.24 6.0 8.0
2:30 351 319 0.25 8.0 10.0
2:45 351 320 0.23 10.0 11.0
3 hrs. 352 320 0.26 10.0 12.0
3:15 352 320 0.22 I1.0 12.0
3:30 353 321 0.26 11.0 13.0
Experiment
No.
2-a
The catalyst absorber and the
was
regenerated
experiment again same conditions
was run under using
the
the regenerated absorber.
catalyst
initial Starting llutant Levels
Po
CO in. 11 ppm
NO in, 29 ppm
NOx in, 33 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min ('F) (F) (ppm) (ppm) (ppm)
:15 144 142 7.75 20.0 20.0
:30 374 142 0.39 5.0 5.0
:45 372 358 0.17 2.0 2.0
1 hr. 371 362 0.15 1.5 2.0
1:15 370 363 0.17 3.0 3.5
1:30 370 363 0.17 4.0 4.5
1:45 368 361 0.18 4.5 5.0
2 hrs. 367 369 0.13 5.0 6.0
2:15 367 360 0.15 6.5 7.5
2:30 366 358 0.17 7.5 8.5
2:45 366 359 0.18 8.0 9.0
3 hrs. 366 358 0.14 9.0 10.0
3:15 366 358 0.17 10.0 11.0
3:30 365 358 0.17 10.0 11.5
3:45 363 356 0.18 10.5 12.0
4 hrs. 362 354 0.17 11.5 13.0
~18~.~37
. W095/21019 PCT/C1S95/0137.t
Experiment No.
2-b
The catalyst absorber was regenerated and the
again
experiment run again unde r the same conditions
was using
the twi ce regenerated absorber.
catalyst
5 'rnitiai Starting Poll+an TPVa 1s
CO in. 11 ppm
NO in, 29 ppm
NOx in, 33 ppm
10 Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min ('F) ('F) (ppm) (ppm) (ppm)
:15 186 142 5.53 18.0 18.0
:30 279 144 2.65 12.0 13.0
15 :45 275 255 0.85 7.0 7.0
1 hr. 271 254 0.65 7.0 7,0
1:15 267 253 0.77 9.0 9.0
1:30 274 255 0.78 10.0 10.0
1:45 283 262 0.73 11.0 11.0
2 hrs. 284 266 0.68 11.0 11.5
2:15 282 266 0.68 13.0 13.0
Experiment No.
2-c
The catalyst absorber was regenerated and the
again
experiment same conditions
was run using
again
under
the
the three lyst
time absorber.
regenerated
cata
r_n_i_t,'_alStartinc LPollutant T.Pve1s
CO in.
9.05
ppm
NO in,
26.0
ppm
NOx in, 32.0 ppm
Time Temp 1 Temp 2 CO out NO out NOx out
Hrs:Min ('F) (F) (ppm) (ppm) (ppm)
:15 354 142 1.06 7.0 7,0
:30 356 150 0.49 2.0 2.0
:45 354 338 0.41 2.0 2.0
1 hr. 351 337 0.43 2.0 3.0
1:15 352 338 0.45 3.0 5.0
1:30 352 339 0.50 6.0 7.0
1:45 352 337 0.50 7.0 g.p
2 hrs. 351 338 0.50 8.0 9.0
2:15 350 336 0.49 8.5 g.5
2:30 349 335 0.50 9.0 10.0
2:45 348 334 0.56 10.0 11.0
3 hrs. 348 334 0.58 11.0 12.0
Experiment 3 First Run
-
This experiment onolith core catalyst
was run
using
a m
in a laboratory set up under the conditions
set forth
below. The space 10,000 initial
velocity hr-ls.
was The
21813:37 . 1
WO 95121019 " % ~ PGT/1TS95/0137a
16
starting pollutant levels are set out at time zero (0)
minutes. Only one catalyst absorber unit was used and the
temperature
was measured
just before
the catalyst
absorber.
Time Temp CO NOx NO Sulfur (S02)
Minutes ('F) (ppm) (ppm) (ppm) (ppm)
Input 351 18.0 33.0 29.0 0.5
concentrations
1 405 0 1.0 0.5
2 415 1.0 0.5 0.35
5 420 0.75 0.059
10 480 0.45 0.004
401 0 0.4 0
15 32 380 2.4 0.004
42 408 2.3 0.007
48 360 1.5 0.001
50 344 1.85 0.002
64 296 5.2 4.2 0.016
20 75 291 8.6 7.1 0.023
85 291 9.0 0.037
Experiment 3 Second n
- Ru
The catalyst absorber was enerated and the experiment
reg
was run again under the same
conditions using
the
regenerated lyst absorber.
cata
Time Temp CO NOx NO Sulfur (S02)
Minutes (F) (ppm) (ppm) (ppm) (ppm)
Input 20.0 34.0 31.0 0.51
Concentrations
0.5 378 0.1 1.8 0.08
1 369 0.1 1.8 0.02
2 343 0.1 1.75 1.55 0.32
3 326 0.1 1.75 1.6 0.19
6 300 0.1 2.0 1.85 0.05
10 286 0.1 2.6 2.6 0.025
12 284 0.1 3.0 0.021
21 287 0.1 5.0 0.021
25 288 0.1 6.2 6.2 0.024
30 291 0.1 9.0 7.9 0.02
47 300 0.1 13.5 12.5 0.05
Experiment No. 4
In the foll owing experiment, starting gas was
the
obtained from slip stream fromthe turb ine exhaust from
a a
cogeneration with Exp eriments 1 and
plant turbine, 2.
as
The catalyst as in Experiments
-has the
same configuration
1 and 2. The the slip stream was 18,000
space
velocity
of
hr 1. The upstream first basket was
temperature
for the
. W0 95121019 2 ~ $13 3 "~f ' PCTICTS9510137;
17
330F and 300F for the downstream second basket. All
pollutant measurements in ppm.
are
Time O NOx NO Np2
Minutes (ppm) (ppm) (ppm) (ppm)
Input 20.0 33 27 6
Concentrations
0 0 1.5 1.5 p
.5 0 1.5 1.5 0
1.5 0 5 5 10
3 0 10 10 0
Apparatus
To apply the catalyst absorber to the continuous
reduction of gaseous pollutants in stack gases, an
apparatus is required. The catalyst absorber is moved
into contact with the stack gas and remains there until the
outlet levels of carbon monoxide, nitrogen oxides and/or
sulfur oxides exceed some specified low concentrations.
The catalyst absorber is then moved out of contact with the
stack gases for regeneration while being replaced with
fresh or previously regenerated catalyst absorber. The
regenerated catalyst absorber is cycled back into contact
with the stack gases in sequence.
The apparatus to apply the catalyst absorber of the
present invention can be in the form of a wheel or
carousel, a portion of which is in contact with the stack
gas and a portion of which is outside of contact with the
stack gas. In this case, the catalyst absorber is mounted
to the wheel and moves in and out of the stack gas stream
as the wheel rotates. The apparatus may alternatively be a
moving continuous belt with the catalyst absorber being
disposed on the belt. Alternatively, a fluidized bed of
the alumina spheres of the catalyst absorbed can be located
in the stack gas stream. In this embodiment a small
fraction of the catalyst absorber, for example,, one percent
per minute, is continuously removed, regenerated and
returned. Any other apparatus could be used to accomplish
the goals specified herein, the choice of such apparatus
depending upon the individual applications.
It would be obvious to a person of ordinary skill in the
WO 95121019 ' PCTIUS95/0137.t
18
art that a number of changes and modifications can be made
to the presently described process, apparatus and methods
without departing from the spirit and scope of the present
invention. It is contemplated that the present invention
is encompassed by the claims as presented herein and by all
variations thereof coming within the scope of equivalents
accorded thereto.
