CA2020501A1 - Process for the production of metal-oxide aerosols for fuel emissions control - Google Patents
Process for the production of metal-oxide aerosols for fuel emissions controlInfo
- Publication number
- CA2020501A1 CA2020501A1 CA002020501A CA2020501A CA2020501A1 CA 2020501 A1 CA2020501 A1 CA 2020501A1 CA 002020501 A CA002020501 A CA 002020501A CA 2020501 A CA2020501 A CA 2020501A CA 2020501 A1 CA2020501 A1 CA 2020501A1
- Authority
- CA
- Canada
- Prior art keywords
- metal
- aerosol
- oxide
- process according
- zone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000443 aerosol Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 44
- 229910044991 metal oxide Inorganic materials 0.000 title claims abstract description 33
- 150000004706 metal oxides Chemical class 0.000 title claims abstract description 33
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 239000000446 fuel Substances 0.000 title description 2
- 229910052751 metal Inorganic materials 0.000 claims abstract description 51
- 239000002184 metal Substances 0.000 claims abstract description 51
- 230000008016 vaporization Effects 0.000 claims abstract description 24
- 230000001590 oxidative effect Effects 0.000 claims abstract description 10
- 239000007800 oxidant agent Substances 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims description 20
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 13
- 229910052791 calcium Inorganic materials 0.000 claims description 13
- 239000011575 calcium Substances 0.000 claims description 13
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 9
- 229910052749 magnesium Inorganic materials 0.000 claims description 9
- 239000011777 magnesium Substances 0.000 claims description 9
- 150000002739 metals Chemical class 0.000 claims description 7
- 239000007787 solid Substances 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 claims description 5
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 4
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 239000002594 sorbent Substances 0.000 abstract description 14
- 239000012159 carrier gas Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 14
- 238000009834 vaporization Methods 0.000 description 9
- 235000019738 Limestone Nutrition 0.000 description 8
- 239000006028 limestone Substances 0.000 description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 7
- 229910052717 sulfur Inorganic materials 0.000 description 7
- 239000011593 sulfur Substances 0.000 description 7
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 6
- 235000012255 calcium oxide Nutrition 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 235000012245 magnesium oxide Nutrition 0.000 description 6
- 239000000292 calcium oxide Substances 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 5
- 239000000395 magnesium oxide Substances 0.000 description 5
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical class [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 3
- 150000002736 metal compounds Chemical class 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 2
- 229940095672 calcium sulfate Drugs 0.000 description 2
- 235000011132 calcium sulphate Nutrition 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000010960 commercial process Methods 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000008092 positive effect Effects 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 206010043414 Therapeutic response decreased Diseases 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 239000012717 electrostatic precipitator Substances 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- 229910052815 sulfur oxide Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/508—Sulfur oxides by treating the gases with solids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/52—Hydrogen sulfide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/68—Halogens or halogen compounds
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/14—Methods for preparing oxides or hydroxides in general
- C01B13/20—Methods for preparing oxides or hydroxides in general by oxidation of elements in the gaseous state; by oxidation or hydrolysis of compounds in the gaseous state
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/02—Oxides or hydroxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/02—Magnesia
- C01F5/04—Magnesia by oxidation of metallic magnesium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Health & Medical Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Treating Waste Gases (AREA)
- Oxygen, Ozone, And Oxides In General (AREA)
- Colloid Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention relates to a process for the production of a metal-oxide aerosol and a process for utilizing the metal-oxide aerosol as an effluent sorbent. The process for producing the metal-oxide aerosol comprises vaporizing the elemental metal in an oxidant free environment under controlled conditions and thereafter oxidizing said vaporized metal under controlled conditions to form an aerosol of said metal-oxide in a carrier gas stream. The aerosol may thereafter be fed to an effluent containing gaseous stream for removal of effluents under controlled temperature conditions.
The present invention relates to a process for the production of a metal-oxide aerosol and a process for utilizing the metal-oxide aerosol as an effluent sorbent. The process for producing the metal-oxide aerosol comprises vaporizing the elemental metal in an oxidant free environment under controlled conditions and thereafter oxidizing said vaporized metal under controlled conditions to form an aerosol of said metal-oxide in a carrier gas stream. The aerosol may thereafter be fed to an effluent containing gaseous stream for removal of effluents under controlled temperature conditions.
Description
2~2~
~9-399 BACKGROUND OF T~IE INVENTION
The present invention relates to a process for the production of a metal-oxide aerosol and a process for utilizing the metal-oxide aerosol as an effluent sorbent.
As is well known, acid gas effluents such as SO2, SO3, NO, NO2, H2S and HCl w~ich are present in off gases from numerous chemical reactions represent primary atmospheric pollutants. ~eretofore, reduction of acid gas effluents in these gaseous streams to environmentally acceptable levels has proven to be extremely costly.
For example, one of the commercial processes used to control SO2 emissions by commercial power plants is in-furnace limestone injection. In accordance wit'n this commercial process, limestone is injected into the commercial furnace where it reacts with sulfur oxides to form solid calcium sul-fate. The solid calcium sulfate particles are thereafter separated from the flue gases by conventional particulate control devices. The major drawback oE the limestone injection process for in-furnace SO2 capture is its low calcium utilization. While the amount of sulfur removed from the combustion products by in-furnace limestone injection is in the order of 50%, calcium utilization is I
89-39~
in the order of only L5 to 25%. As a result, extremely large quantities of limestone must be injected per unit mass of sulfur contained in the fuel. This has proven to be quite costl~.
Naturally, it would be highly desirable to provide a mechanism for removing effluents Erom industrial combustion streams in an economic manner.
AccordingLy, it is a principle object of the present invention to provide a process for the production of an effluent sorbent aerosol material.
It is a further object of the present invention to provide a process for the production of an effluent sorbent-oxide aerosol for removing acid gas effluents from a gaseous stream which is highly effective.
Further objects and advantages of t'ne present invention will appear hereinbelow.
SUMMARY OF THE INVENTION
In accordance with the present invention, the foregoing objects and advantages are readily obtained.
The present invention is drawn to a process for the production of a metal-oxide aerosol from a corresponding metal and a process for utilizing the metal-oxide aerosol as an effluent sorbentO The process of the present invention comprises vaporizing a metal'of '3,~'3 desired sorbent in an oxidant free environment and, preferably, in a gaseous stream o-E an inert gas under vaporizing temperature conditions at a temperature T~
in a first zone. The vaporized metal gaseous stream is thereafter passed from the first zone to a second zone wherein the metal vapor stream is contacted with an oxidant so as to oxidize the metal vapor thereby forming an aerosol consisting of solid metal-oxide particles in a gaseous carrier stream. By controlling various parameters of the process, the size of the metal-oxide particles may be controlled so as to produce an optimized metal oxide aerosol. The metal oxide aerosol is thereafter fed to a gaseous stream containing acid gas effluents and is contacted therewith at a temperature suitable for the reaction between the metal oxide aerosol and the effluent to be captured so as to form a solid metal compound of the effluent.
BRIEF ~ESCRIPTION OF THE DRAWINGS
Figure l is a schematic illustration of the process of the present invention for producing a metal-oxide aerosol and for removing effluents from a gaseous stream using the metal-oxide aerosol.
2~20~
89-3g9 Figwre 2 is a graph illustrating the eefluent absorption capabilities of the process of the present invention empl.oying calcium as the sorbent metal and sulfur as the effluënt.
Figure 3 is a graph illustrating the effluent absorption capabili-ties of the process of the present invention employing magnesium as the sorbent metal and sulfur as the effluent.
DETAILED DESCRIPTION
The present invention relates to a process for the production of a metal-oxide aerosol and a process for utilizing the metal-oxide aerosol so produced as an effluent sorbent. The process is particularly useful in removing acid gas effluents such as SO2, SO3, NO, NO2, H2S and HCl which are by~products from various chemical reactions from the off gases of the chemical reactions.
The process of the present invention will be described in detail with reference to Figure l and -the schematic illustrations shown therein.
The process of the present invention comprises the production of a metal-oxide aerosol and its s~bsequent formation into a solid metal compound of the effluent being captured. ~hile the process will be described and 89-399 2~2~5~
illustrated employing sulfur as the effluent in a combustion gas stream, the process is useful in capturing all the acid gas effluents mentioned above which are by-products of numerous chemical reactions.
With reference to Figure l, the metal-oxide aerosol is produced by vaporizing a metal of the desired sorbent under vaporizing temperature conditions in a vaporizing zone which is an oxidant free environment and thereafter passing the metal vapor so produced to an oxidizing zone wherein the metal vapor is contacted with an oxidant so as to produce a metal oxide aerosol.
In accordance with the process of the present invention, suitable sorbent metals for use in the process of the present invention are the metals selected from the group consisting of alkaline metals, alkaline earth metals, metals having a valence greater than or equal to the alkaline earth metals and mixtures thereof. Particularly suitable metals are magnesium and calcium with calcium being preferred. It is preferred in the process of the present invention to vaporize the desired metal sorbent in the vaporizing zone in a gaseous stream. It is necessary for the gaseous stream to be an inert gaseous stream and may be of any of the following gases: argon, helium, nitrogen, ma,hane, etc. Preferred gases would be aryon, nitrogen.' Inert 89-399 2~20~
gases are required because t'ne vaporiza-tion step must take place in a substantial]y oxi-lant free environment in order -to insure complete vaporization of the metal sorben-t. The use of an inert gaseous stream is desirable because it increases the amount of metal vapor in the gaseous stream, that is metal vapor load, which has a positive effect on the particle size on the metal oxide produced. The flow rate of the gaseous stream should be adjusted so as to produce the desired aerosol characteristic for a suitable particle size of the metal oxide aerosol (smaller than a 0.1 mircon). The required inert gas flow should be adjusted to produce a metal vapor load of 5 g/Nm to 250 g/Nm and preferably about 50 to 150 g/Nm .
The inert gas flow rate depends on several factors such as metal vaporization temperature (Tl), t~vpe of metal to be vaporized, ~uenching rate used in the aerosol formation step, desired aerosol primary particle size, among others. The inert gas flow rate used in the process oE the present invention is preferably chosen to provide a suitable metal vapor load that will subsequently produce an adequate aerosol primary particle size of about 0.05 microns mean diameter which is ideally suitable for obtaining a high metal utilization in the effluent absorption step.
89-399 ~ 5~
In accordance wl-th the present invention, it is necessary for the vaporization of the metal in the gaseous stream in the first zone of the furnace to be conducted at controlled temperature conditions Tl at a pressure Pl. The temperature T1 is the temperature that is necessary in order to obtain complete metal vaporization, that is, the melting point of the metal, and will vary depending on the metal sorbent to be vaporized. In addition, in order to obtain complete metal vaporization, the vaporizing zone must be substantially oxidant free. Further~ore, the temperature employed for vaporization is preferably significantly higher than the melting point of the metal sorbent employed. This is desirous because an increase in temperature Tl increases vapor load in the stream fed to the oxidation zone which, as noted above, has a positive effect on the metal oxide particle size. For cost reasons, the temperature of vaporization should be below 2000C. ~n accordance with the present inven-tion the vaporization temperature is about between o50 to 1200C, preferably 1000 to 1300C for calcium and between 450 to 1150C, preferably 750 to 950C for magnesium at atmospheric pressure.
Once the metal vapor is produced in the vaporizing zone, the metal vapor in the gaseous stream with or ~9_399 ~3~V~
without the inert gaseous stream is passed from the first zone of t~e furnace to a second zone. The metal vapor in the gaseous stream is contacted in the second zone of the furnace with an oxidant such as oxygen, air, C2 and the llke so as to oxidiæe the metal vapor to form the aerosol o~ the present invention which comprises the metaL-oxide particles in the gaseous stream of carrier gas. In accordance wit'n the present invention, the formation of the aerosol stream in the second zone should be controlled as to produce the required particle size. It has been found tha-t submicron particle sized metal oxide particles are desirable in order to obtain effective sorbent utilization and correspondingly good effluent capture.
A mean particle size of less than O.l microns is preferred with particle sizes of less than 0.05 being ideal.
As noted above, the aerosol stream fed from the second zone is contacted with an effluen-t carrying gaseous stream in a third zone under controlled temperature conditions. The temperature at which the metal oxide aerosol contacts the effluent carrying gaseous stream must be within the temperature range suitable for the reaction between the metal oxide aerosol and the effluent to be captured so as tb form a solid metal compound of the effluent. For example, in 89-399 20205~
the case of sulfur, the ef~luent absorption step is carried out under the foLlowing conditions: 650 to 1250~C and preferably between about 950c to 1200C for calcium oxide aerosol and about between 350 and 850C
and preferably between about 700 and 800C for magnesium. These temperature ranges represent the practical and/or thermodynamic limits for the sulEation of calcium and magnesium oxides.
In accordance with the process of the present invention, sorbent utilization is greater than or equal to about 90% and 50% for CaO aerosol and MgO aerosol, respectively, for a gas stream containing about 2000 ppm o-f SO2.
The following examples illustrate specific features of the process of the present invention but in no way are intended to be limiting.
EXAMPI.E I
With re-ference to Figures 1 and 2, 3.5 g of calcium metal was fed to a vaporizing zone. Argon gas was fed to the zone at a gas flow rate of 15.~ ml/sec., a temperature of 25C and 1 atm. pressure. The zone was heated to a temperature of 1000C. Under these conditions a steady production of an aerosol of about 5 mg/min. was measured. The aerosol stream was ~ontacted 2 ~
89-39g with a stream of 54 l/min. of heatecl dry air at a temperature of 950C in an oxidation zone so as to æroduce a metal oxide aerosol o~ CaO. The aerosol was injected into a gaseous stream having a measured amount f S2 and was contac-ted with the aerosol stream in an effluent ahsorption zone. Five separate runs were made with SO2 concentrations measured in volume parts per million in the air of 250, 500, 750, 2000 and 3500. An electrostatic precipitator sampling probe was located at the end of the absorption zone to capture the aerosol samples. Aerosol samples were taken in order to determine the amount of calcium utilized in sulfur absorption. The results are shown in Figure 2. It is important -to note that the residence time used in this experiment, about 0.5 seconds, is well within the time span spent by the flue gases inside industrial boilers to drop from 1200 to 950C. Therefore, the results presented are well within the required industrial time frame. As can be seen from Figure 2, the ca~cium utilization is greater than 80~ at SO2 concentrations of above 1500 ppm which is far superior to that utilization obtained from in-furnace limestone injection processes. In addition to the foregoing, the temperature at which effluent absorption takes place, 25 that is, 950C for calcium and 800C for magnesium, are 3~0~
much lower than those used in in-furnace limestone injection processes thereby making the process of the present invention even more attractive. Finally, the average particle aiameter of calcium oxide was measured and found to be 0.015 Jum.
EXAMPL.E II
The process of Example II was similar to that set forth above with regard to Example I but employed magnesium rather than calcium. The magnesium oxide aerosol was generated and then fed to the five S02 containing air streams set forth above with regard to Example I. In order to vaporize magnesium, the temperature in the first zone was adjusted to 850C.
The results are set forth in Figure 3. It can be seen that an aerosol containing magnesium oxide particles is not as effec-tive as an aerosol containing calcium oxide particles at low SO2 concentrations of S02, however, the magnesium oxide aerosol is still superior to known in-furnace limestone injection processes. The particle size of the magnesium oxide particle obtained in -the aerosol in accordance wit'n this example was 0.020 ~mO
This invention may be embodied in other forms or carried out in other ways wit'nout departing from the spirit or essential characteristics thereof. The '~ ~ `2 ~
present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended c:Laims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
~9-399 BACKGROUND OF T~IE INVENTION
The present invention relates to a process for the production of a metal-oxide aerosol and a process for utilizing the metal-oxide aerosol as an effluent sorbent.
As is well known, acid gas effluents such as SO2, SO3, NO, NO2, H2S and HCl w~ich are present in off gases from numerous chemical reactions represent primary atmospheric pollutants. ~eretofore, reduction of acid gas effluents in these gaseous streams to environmentally acceptable levels has proven to be extremely costly.
For example, one of the commercial processes used to control SO2 emissions by commercial power plants is in-furnace limestone injection. In accordance wit'n this commercial process, limestone is injected into the commercial furnace where it reacts with sulfur oxides to form solid calcium sul-fate. The solid calcium sulfate particles are thereafter separated from the flue gases by conventional particulate control devices. The major drawback oE the limestone injection process for in-furnace SO2 capture is its low calcium utilization. While the amount of sulfur removed from the combustion products by in-furnace limestone injection is in the order of 50%, calcium utilization is I
89-39~
in the order of only L5 to 25%. As a result, extremely large quantities of limestone must be injected per unit mass of sulfur contained in the fuel. This has proven to be quite costl~.
Naturally, it would be highly desirable to provide a mechanism for removing effluents Erom industrial combustion streams in an economic manner.
AccordingLy, it is a principle object of the present invention to provide a process for the production of an effluent sorbent aerosol material.
It is a further object of the present invention to provide a process for the production of an effluent sorbent-oxide aerosol for removing acid gas effluents from a gaseous stream which is highly effective.
Further objects and advantages of t'ne present invention will appear hereinbelow.
SUMMARY OF THE INVENTION
In accordance with the present invention, the foregoing objects and advantages are readily obtained.
The present invention is drawn to a process for the production of a metal-oxide aerosol from a corresponding metal and a process for utilizing the metal-oxide aerosol as an effluent sorbentO The process of the present invention comprises vaporizing a metal'of '3,~'3 desired sorbent in an oxidant free environment and, preferably, in a gaseous stream o-E an inert gas under vaporizing temperature conditions at a temperature T~
in a first zone. The vaporized metal gaseous stream is thereafter passed from the first zone to a second zone wherein the metal vapor stream is contacted with an oxidant so as to oxidize the metal vapor thereby forming an aerosol consisting of solid metal-oxide particles in a gaseous carrier stream. By controlling various parameters of the process, the size of the metal-oxide particles may be controlled so as to produce an optimized metal oxide aerosol. The metal oxide aerosol is thereafter fed to a gaseous stream containing acid gas effluents and is contacted therewith at a temperature suitable for the reaction between the metal oxide aerosol and the effluent to be captured so as to form a solid metal compound of the effluent.
BRIEF ~ESCRIPTION OF THE DRAWINGS
Figure l is a schematic illustration of the process of the present invention for producing a metal-oxide aerosol and for removing effluents from a gaseous stream using the metal-oxide aerosol.
2~20~
89-3g9 Figwre 2 is a graph illustrating the eefluent absorption capabilities of the process of the present invention empl.oying calcium as the sorbent metal and sulfur as the effluënt.
Figure 3 is a graph illustrating the effluent absorption capabili-ties of the process of the present invention employing magnesium as the sorbent metal and sulfur as the effluent.
DETAILED DESCRIPTION
The present invention relates to a process for the production of a metal-oxide aerosol and a process for utilizing the metal-oxide aerosol so produced as an effluent sorbent. The process is particularly useful in removing acid gas effluents such as SO2, SO3, NO, NO2, H2S and HCl which are by~products from various chemical reactions from the off gases of the chemical reactions.
The process of the present invention will be described in detail with reference to Figure l and -the schematic illustrations shown therein.
The process of the present invention comprises the production of a metal-oxide aerosol and its s~bsequent formation into a solid metal compound of the effluent being captured. ~hile the process will be described and 89-399 2~2~5~
illustrated employing sulfur as the effluent in a combustion gas stream, the process is useful in capturing all the acid gas effluents mentioned above which are by-products of numerous chemical reactions.
With reference to Figure l, the metal-oxide aerosol is produced by vaporizing a metal of the desired sorbent under vaporizing temperature conditions in a vaporizing zone which is an oxidant free environment and thereafter passing the metal vapor so produced to an oxidizing zone wherein the metal vapor is contacted with an oxidant so as to produce a metal oxide aerosol.
In accordance with the process of the present invention, suitable sorbent metals for use in the process of the present invention are the metals selected from the group consisting of alkaline metals, alkaline earth metals, metals having a valence greater than or equal to the alkaline earth metals and mixtures thereof. Particularly suitable metals are magnesium and calcium with calcium being preferred. It is preferred in the process of the present invention to vaporize the desired metal sorbent in the vaporizing zone in a gaseous stream. It is necessary for the gaseous stream to be an inert gaseous stream and may be of any of the following gases: argon, helium, nitrogen, ma,hane, etc. Preferred gases would be aryon, nitrogen.' Inert 89-399 2~20~
gases are required because t'ne vaporiza-tion step must take place in a substantial]y oxi-lant free environment in order -to insure complete vaporization of the metal sorben-t. The use of an inert gaseous stream is desirable because it increases the amount of metal vapor in the gaseous stream, that is metal vapor load, which has a positive effect on the particle size on the metal oxide produced. The flow rate of the gaseous stream should be adjusted so as to produce the desired aerosol characteristic for a suitable particle size of the metal oxide aerosol (smaller than a 0.1 mircon). The required inert gas flow should be adjusted to produce a metal vapor load of 5 g/Nm to 250 g/Nm and preferably about 50 to 150 g/Nm .
The inert gas flow rate depends on several factors such as metal vaporization temperature (Tl), t~vpe of metal to be vaporized, ~uenching rate used in the aerosol formation step, desired aerosol primary particle size, among others. The inert gas flow rate used in the process oE the present invention is preferably chosen to provide a suitable metal vapor load that will subsequently produce an adequate aerosol primary particle size of about 0.05 microns mean diameter which is ideally suitable for obtaining a high metal utilization in the effluent absorption step.
89-399 ~ 5~
In accordance wl-th the present invention, it is necessary for the vaporization of the metal in the gaseous stream in the first zone of the furnace to be conducted at controlled temperature conditions Tl at a pressure Pl. The temperature T1 is the temperature that is necessary in order to obtain complete metal vaporization, that is, the melting point of the metal, and will vary depending on the metal sorbent to be vaporized. In addition, in order to obtain complete metal vaporization, the vaporizing zone must be substantially oxidant free. Further~ore, the temperature employed for vaporization is preferably significantly higher than the melting point of the metal sorbent employed. This is desirous because an increase in temperature Tl increases vapor load in the stream fed to the oxidation zone which, as noted above, has a positive effect on the metal oxide particle size. For cost reasons, the temperature of vaporization should be below 2000C. ~n accordance with the present inven-tion the vaporization temperature is about between o50 to 1200C, preferably 1000 to 1300C for calcium and between 450 to 1150C, preferably 750 to 950C for magnesium at atmospheric pressure.
Once the metal vapor is produced in the vaporizing zone, the metal vapor in the gaseous stream with or ~9_399 ~3~V~
without the inert gaseous stream is passed from the first zone of t~e furnace to a second zone. The metal vapor in the gaseous stream is contacted in the second zone of the furnace with an oxidant such as oxygen, air, C2 and the llke so as to oxidiæe the metal vapor to form the aerosol o~ the present invention which comprises the metaL-oxide particles in the gaseous stream of carrier gas. In accordance wit'n the present invention, the formation of the aerosol stream in the second zone should be controlled as to produce the required particle size. It has been found tha-t submicron particle sized metal oxide particles are desirable in order to obtain effective sorbent utilization and correspondingly good effluent capture.
A mean particle size of less than O.l microns is preferred with particle sizes of less than 0.05 being ideal.
As noted above, the aerosol stream fed from the second zone is contacted with an effluen-t carrying gaseous stream in a third zone under controlled temperature conditions. The temperature at which the metal oxide aerosol contacts the effluent carrying gaseous stream must be within the temperature range suitable for the reaction between the metal oxide aerosol and the effluent to be captured so as tb form a solid metal compound of the effluent. For example, in 89-399 20205~
the case of sulfur, the ef~luent absorption step is carried out under the foLlowing conditions: 650 to 1250~C and preferably between about 950c to 1200C for calcium oxide aerosol and about between 350 and 850C
and preferably between about 700 and 800C for magnesium. These temperature ranges represent the practical and/or thermodynamic limits for the sulEation of calcium and magnesium oxides.
In accordance with the process of the present invention, sorbent utilization is greater than or equal to about 90% and 50% for CaO aerosol and MgO aerosol, respectively, for a gas stream containing about 2000 ppm o-f SO2.
The following examples illustrate specific features of the process of the present invention but in no way are intended to be limiting.
EXAMPI.E I
With re-ference to Figures 1 and 2, 3.5 g of calcium metal was fed to a vaporizing zone. Argon gas was fed to the zone at a gas flow rate of 15.~ ml/sec., a temperature of 25C and 1 atm. pressure. The zone was heated to a temperature of 1000C. Under these conditions a steady production of an aerosol of about 5 mg/min. was measured. The aerosol stream was ~ontacted 2 ~
89-39g with a stream of 54 l/min. of heatecl dry air at a temperature of 950C in an oxidation zone so as to æroduce a metal oxide aerosol o~ CaO. The aerosol was injected into a gaseous stream having a measured amount f S2 and was contac-ted with the aerosol stream in an effluent ahsorption zone. Five separate runs were made with SO2 concentrations measured in volume parts per million in the air of 250, 500, 750, 2000 and 3500. An electrostatic precipitator sampling probe was located at the end of the absorption zone to capture the aerosol samples. Aerosol samples were taken in order to determine the amount of calcium utilized in sulfur absorption. The results are shown in Figure 2. It is important -to note that the residence time used in this experiment, about 0.5 seconds, is well within the time span spent by the flue gases inside industrial boilers to drop from 1200 to 950C. Therefore, the results presented are well within the required industrial time frame. As can be seen from Figure 2, the ca~cium utilization is greater than 80~ at SO2 concentrations of above 1500 ppm which is far superior to that utilization obtained from in-furnace limestone injection processes. In addition to the foregoing, the temperature at which effluent absorption takes place, 25 that is, 950C for calcium and 800C for magnesium, are 3~0~
much lower than those used in in-furnace limestone injection processes thereby making the process of the present invention even more attractive. Finally, the average particle aiameter of calcium oxide was measured and found to be 0.015 Jum.
EXAMPL.E II
The process of Example II was similar to that set forth above with regard to Example I but employed magnesium rather than calcium. The magnesium oxide aerosol was generated and then fed to the five S02 containing air streams set forth above with regard to Example I. In order to vaporize magnesium, the temperature in the first zone was adjusted to 850C.
The results are set forth in Figure 3. It can be seen that an aerosol containing magnesium oxide particles is not as effec-tive as an aerosol containing calcium oxide particles at low SO2 concentrations of S02, however, the magnesium oxide aerosol is still superior to known in-furnace limestone injection processes. The particle size of the magnesium oxide particle obtained in -the aerosol in accordance wit'n this example was 0.020 ~mO
This invention may be embodied in other forms or carried out in other ways wit'nout departing from the spirit or essential characteristics thereof. The '~ ~ `2 ~
present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended c:Laims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
Claims (10)
1. A process for the production of a metal-oxide aerosol from a corresponding metal comprising vaporizing said metal under vaporizing temperature conditions in a first zone at a temperature greater than or equal to Tl, passing said metal vapor in a gaseous stream from said first zone to a second zone, and contacting said metal vapor with an oxidant in said second zone so as to oxidize said metal vapor to form an aerosol comprising solid metal-oxide particles in said gaseous stream.
2, A process according to claim 1 wherein said metal is selected from the group consisting of alkaline metals, alkaline earth metals, metals having a valence greater than or equal to the alkaline earth metals and mixtures thereof.
3. A process according to claim 2 wherein said metal is selected from the group consisting of magnesium and calcium.
4. A process according to claim 1 wherein a gaseous stream of an inert gas is fed to said first zone during the vaporizing of said metal.
5. A process according to claim 4 wherein the metal vapor load on said gaseous stream is between about 5 g/Nm3 to 250 g/Nm3.
6. A process according to claim 1 wherein temperature TL is the melting temperature of the metal being vaporized.
7. A process according to claim 1 wherein the metal is magnesium and the vaporizing temperature is between about 450° to 1150°C at atmospheric pressure.
8. A process according to claim 1 wherein the metal is calcium and the vaporizing temperature is between about 650° to 1300°C at atmospheric pressure.
9. A process according to claim 1 wherein said aerosol is characterized by a metal-oxide particle size of between about 0.001 to 1.0 micrometer.
10. A process according to claim 1 further including the step of contacting said aerosol with an effluent containing gaseous stream under controlled temperature conditions whereby said metal-oxide particles react with said effluent for absorbing same.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49889290A | 1990-03-26 | 1990-03-26 | |
| US498,892 | 1990-03-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2020501A1 true CA2020501A1 (en) | 1991-09-27 |
Family
ID=23982937
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002020501A Abandoned CA2020501A1 (en) | 1990-03-26 | 1990-07-05 | Process for the production of metal-oxide aerosols for fuel emissions control |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPH03275506A (en) |
| BE (1) | BE1005343A4 (en) |
| BR (1) | BR9003819A (en) |
| CA (1) | CA2020501A1 (en) |
| DE (1) | DE4038195A1 (en) |
| DK (1) | DK160490A (en) |
| ES (1) | ES2020732A6 (en) |
| FR (1) | FR2659873A1 (en) |
| GB (1) | GB2242421A (en) |
| IT (1) | IT1241567B (en) |
| NL (1) | NL9001656A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5499587A (en) * | 1986-06-17 | 1996-03-19 | Intevep, S.A. | Sulfur-sorbent promoter for use in a process for the in-situ production of a sorbent-oxide aerosol used for removing effluents from a gaseous combustion stream |
| JP4195278B2 (en) * | 2002-12-02 | 2008-12-10 | 宇部マテリアルズ株式会社 | Metallic magnesium melt evaporation apparatus and method for producing high-purity magnesium oxide fine powder using the same |
| JP4855452B2 (en) * | 2008-08-25 | 2012-01-18 | 宇部マテリアルズ株式会社 | Metallic magnesium melt evaporation apparatus and method for producing high-purity magnesium oxide fine powder using the same |
| US8758710B2 (en) | 2010-06-15 | 2014-06-24 | E.T. Energy Corp. | Process for treating a flue gas |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1558356A1 (en) * | 1966-02-03 | 1970-07-23 | Horn Dr Lutz | Powder produced by means of the action of ultrasound on a molten metal by atomizing the metal and process for its production |
| US3743708A (en) * | 1970-11-20 | 1973-07-03 | American Cyanamid Co | Submicron metal oxide particles and their process for manufacture |
| JPS59213619A (en) * | 1983-05-20 | 1984-12-03 | Ube Ind Ltd | Preparation of fine magnesia powder having high purity |
| JPS60161329A (en) * | 1984-01-26 | 1985-08-23 | Ube Ind Ltd | Preparation of fine calcia powder having high purity |
| JPS60175537A (en) * | 1984-02-22 | 1985-09-09 | Toyota Motor Corp | Preparation of ultra-fine ceramic particles |
| JPS61122106A (en) * | 1984-11-19 | 1986-06-10 | Ube Ind Ltd | Production of metal oxide fine powder |
| US4534572A (en) * | 1984-12-20 | 1985-08-13 | Dana Corporation | Port baffle for engine gasket |
| JPS6243928A (en) * | 1985-08-21 | 1987-02-25 | Matsushita Electric Ind Co Ltd | Digital communication method |
| JPH068170B2 (en) * | 1985-10-29 | 1994-02-02 | 宇部興産株式会社 | Method for producing high-purity magnesium oxide fine powder |
| US4726940A (en) * | 1986-05-21 | 1988-02-23 | Hitachi Zosen Corporation | Method of purifying exhaust gas |
| JPS6458131A (en) * | 1987-08-28 | 1989-03-06 | Tokyo Electric Co Ltd | Data transmission system |
| JP2792046B2 (en) * | 1987-10-09 | 1998-08-27 | 住友化学工業株式会社 | Optically active amine-boron compound, asymmetric reducing agent containing the same as an active ingredient, and method for producing optically active compound using the same |
-
1990
- 1990-07-03 DK DK160490A patent/DK160490A/en not_active IP Right Cessation
- 1990-07-05 CA CA002020501A patent/CA2020501A1/en not_active Abandoned
- 1990-07-09 GB GB9015112A patent/GB2242421A/en not_active Withdrawn
- 1990-07-19 NL NL9001656A patent/NL9001656A/en not_active Application Discontinuation
- 1990-08-03 BR BR909003819A patent/BR9003819A/en not_active Application Discontinuation
- 1990-08-07 ES ES9002138A patent/ES2020732A6/en not_active Expired - Fee Related
- 1990-09-21 IT IT67707A patent/IT1241567B/en active IP Right Grant
- 1990-10-03 FR FR9012186A patent/FR2659873A1/en active Pending
- 1990-10-12 BE BE9000969A patent/BE1005343A4/en not_active IP Right Cessation
- 1990-11-28 JP JP2328760A patent/JPH03275506A/en active Pending
- 1990-11-30 DE DE4038195A patent/DE4038195A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| NL9001656A (en) | 1991-10-16 |
| DE4038195A1 (en) | 1991-10-02 |
| GB9015112D0 (en) | 1990-08-29 |
| DK160490D0 (en) | 1990-07-03 |
| DK160490A (en) | 1991-09-27 |
| ES2020732A6 (en) | 1991-09-01 |
| IT9067707A0 (en) | 1990-09-21 |
| GB2242421A (en) | 1991-10-02 |
| IT1241567B (en) | 1994-01-18 |
| BR9003819A (en) | 1991-11-12 |
| FR2659873A1 (en) | 1991-09-27 |
| JPH03275506A (en) | 1991-12-06 |
| IT9067707A1 (en) | 1992-03-21 |
| BE1005343A4 (en) | 1993-07-06 |
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