CA1235863A - Steam cooled spout - Google Patents
Steam cooled spoutInfo
- Publication number
- CA1235863A CA1235863A CA000479074A CA479074A CA1235863A CA 1235863 A CA1235863 A CA 1235863A CA 000479074 A CA000479074 A CA 000479074A CA 479074 A CA479074 A CA 479074A CA 1235863 A CA1235863 A CA 1235863A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- smelt
- heat exchanging
- flow
- wall
- 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.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J4/00—Feed or outlet devices; Feed or outlet control devices
- B01J4/001—Feed or outlet devices as such, e.g. feeding tubes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/12—Combustion of pulp liquors
- D21C11/122—Treatment, e.g. dissolution, of the smelt
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/14—Charging or discharging liquid or molten material
- F27D3/145—Runners therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D9/00—Cooling of furnaces or of charges therein
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
STEAM COOLED SPOUT
ABSTRACT OF DISCLOSURE
A substantially energy saving steam cooled spout, offering reduced explosion hazards, the invention includes a heat resistant heat exchanging metallic wall having one surface to convey a flow of molten smelt. A second heat resistant wall joins the heat exchanging metallic wall to define with the opposite surface thereof, a passage for a flow of steam, against the heat exchanging metallic wall.
The heat exchanging metallic wall thereby provides a heat exchange from the flow of molten smelt to the flow of steam. Baffles are mounted in the passage to define a tortuous path therein in order to increase the path of the steam over the heat exchanging metallic wall, thereby in-creasing the temperature of the steam to bring the steam to a superheated condition. Means are provided for directing the steam in superheated condition into the flow of molten smelt. A method for transfering a molten smelt is also described wherein a flow of molten smelt is cooled by a flow of steam, which are separated by a heat exchanging metallic wall, whereby the flow of steam is heated and brought to a superheated condition while the flow of molten smelt and the heat exchanging metallic wall are cooled to reduce the heat stressing conditions of the heat exchanging wall and while the steam, in superheated condition, offers reduced explosion hazards when in contact with the molten smelt.
ABSTRACT OF DISCLOSURE
A substantially energy saving steam cooled spout, offering reduced explosion hazards, the invention includes a heat resistant heat exchanging metallic wall having one surface to convey a flow of molten smelt. A second heat resistant wall joins the heat exchanging metallic wall to define with the opposite surface thereof, a passage for a flow of steam, against the heat exchanging metallic wall.
The heat exchanging metallic wall thereby provides a heat exchange from the flow of molten smelt to the flow of steam. Baffles are mounted in the passage to define a tortuous path therein in order to increase the path of the steam over the heat exchanging metallic wall, thereby in-creasing the temperature of the steam to bring the steam to a superheated condition. Means are provided for directing the steam in superheated condition into the flow of molten smelt. A method for transfering a molten smelt is also described wherein a flow of molten smelt is cooled by a flow of steam, which are separated by a heat exchanging metallic wall, whereby the flow of steam is heated and brought to a superheated condition while the flow of molten smelt and the heat exchanging metallic wall are cooled to reduce the heat stressing conditions of the heat exchanging wall and while the steam, in superheated condition, offers reduced explosion hazards when in contact with the molten smelt.
Description
~23~
FIELD OF THE INVENTION
This invention relates to a steam cooled spout for transfering a molten smelt and to a method of transfering a molten smelt. More particularly, this invention relates to a steam cooled spout for transfering molten smelt such as in chemical recovery furnaces and to a method therefor.
BACKGROUND OF THE INVENTION
In the Pulp & Paper Industry, recovering furnaces are used in order to obtain valuable products from black liquors or from other sources of materials used during the production of pulp and paper. The byproduct of this process is commonly attained in a molten smelt which is highly viscous and at temperatures ranging from 1800 to 2000 F.
In many instances, the molten liquid smelt (herein referred to as "smelt") needs to be transferred. For instance, one may wish to convert it to a white liquor to be reused.
When one wishes such a transfer, spouts are generally used. However, due to the high temperature of the smelt, the spouts need to be cooled or insulated to prevent extreme damage thereto. One example of such spouts is described in United States Patent 3,122,421 as invented by T.G. Gettle, where water is circulated through pipes to cool the spout. Water is generally the well accepted coolant for its economy.
However, this transfer procedure presents both uneconomical and serious hazardous difficulties due to the explosive characteristics of the smelt. Any contact of the smelt with the water or other similar cooling material ~ 3S~3 results in a sudden expansion of the cooling material, thereby causing an explosion.
of a further concern are the extreme conditions of heat and friction inherent in the smelt, which must be withstood in order to provide both hazard-free and economical transfer of smelt.
One method of overcoming this problem has been to cover the spout with refactory lining to insulate against heat while providing a surface to absorb the friction caused by the flowing smelt. It has also been described in United States Patent 4,011,047 as invented by Tremblay, a spout having a refractory lining and in which steam is used to intercept the trajectory of the smelt and to disintegrate the smelt into particles and where the steam is partly heated with the heat derived from the bottom wall of the spout.
This was used, for instance, on recovery furnaces in the Pulp & Paper Industry. Spouts of this nature provided operating periods in keeping with those of the recovery furnace since both employed the same lining. However, such a lining under drastic conditions has a life span in the order of months.
Recovery boiler technology has since advanced to the use of water cooling in lieu of refractory linings which provided substantial improvements in maintenance~free operation time periods. In response, attempts were made to incorporate water cooling of the smelt spout in lieu of the refactory lining therein. However, the water cooled spouts were found to be hazardous since any contact of the smelt with the cooling water caused damaging explosions.
~3~i3 In some instances, the explosions caused a breakup of the spout producing a chain reaction of subsequent larger explosions.
BRIEF DESCRIPTION OF THE PRESENT INVENTION
It is therefore an object of the present invention to provide an improved steam cooled spout having substantially increased maintenance-free operating periods while substantially eliminating and if not, substantially reducing the explosive hazards associated with present spouts, and an improved method of transfering a molten smelt.
Briefly stated, the invention comprises a substant-ially energy saving steam cooled spout offering reduced explosion hazards, comprising a substantially heat resistant heat exchanging metallic wall, defining a spout for receiving and conveying a smelt and contacting said smelt against one surface of said heat exchanging metallic wall, and wherein on the opposite surface of said heat exchanging metallic wall, a second heat resistant wall joins said heat exchanging metallic wall, and deEines with said opposite surface a passage for a flow of steam along said heat exchanging metallic wall, and mounted within said passage a plurality of baffle means joining said heat exchanging metallic wall to said second wall as to define a tortuous path to increase the path of said steam over said heat exchanging metallic wall, to raise the temper-ature of said steam, and said tortuous path boosts said temperature to obtain steam in a superheated condition, while cooling said heat exchanging metallic wall and thereby said smelt, and reducing the stress caused on said heat exchanging metallic wall by said molten smelt, said passage at the outlet end being provided with means fGr directing said flow of steam in said superheated condition into said flow of molten smelt, said steam, in said superheated condition having minimum explosive expansion characteristics, when in contact with said molten smelt.
The invention is also directed to a method of transfering a molten smelt offering reduced explosion hazards comprising: conveying on one surface of a heat exchanging metallic wall, and near one end of said sur ace a flow of molten smelt, allowing said flow of smelt to be displaced to the other end of said surface of said heat exchanging metallic wall, bringing into heat transfer relationship the opposite surface of said heat exchanging metallic wall near said one end to near said other end, a tortuous flow of steam causing heat to be continuously transferred from said flow of smelt to said flow of steam thereby bringing said flow of steam to a superheated condition, while cooling said heat exchanging metallic wall and thereby said smelt, and enabling the temperature of said steam, in said superheated condition to approach the temperature of said smelt to reduce the heat stressing conditions of said heat exchanging metallic wall, and to obtain steam, in superheated condition with minimum explosive expansion, said steam offering reduced explosion hazards when in contact with the molten smelt.
By the term "smelt" used throughout the claims and disclosure, is meant a molten slag in a liquid state.
Examples of preferred smelt include slag obtained from black liquor frorn a recovery furnace. If desired, other ~2~s~3 slags may also be used as long as they are compatible with steam and with the heat resistant heat exchanging metallic wall.
DESCRIPTION OF THE DRAWINGS
A particular embodiment of the present invention will now be described in detail having reference to the accompanying drawinys in which:
Figure 1 is a cross-sectional drawing of a smelt spout.
Figure 2 is an end view of the smelt spout, with respect to line 2-2 in Figure 1.
Figure 3 is a rear sectional view of the smelt spout with respect to lines 3a-3a and 3b-3b of Figure 1.
Figure 4 is a front view of the smelt spout with respect to line 4-4 of Figure 1.
Now, referring to Figure 1, the smelt spout 10 has a conveniently trough-shaped heat exchanging metallic wall 12 (herein referred to as "trough") having a surface 12a (better shown in Figure 2) to receive,confine and convey a flow of smelt shown by dashed lines 13. Other shapes may be used if desired. Surrounding the trough 12 and joined thereto is a second wall 14 for defining with the steam surface 12b of trough 12 (better shown in Figure 2), a passage 16 for a flow of steam. The passage 16 is provided with a steam inlet 18 and superheated steam outlets l9a and l9b.
Closing the upstream and downstream ends of passage 16 are upstream and downstream wall portions 20 and 21 respectively. Positioned with respect to the upstream wall portion 20 are a plura1ity of baffles genera11y shown ~35W3 at 22 to direct the flow of steam from inlet 18 to the passage 16 beneath the central section 12c of trough 12 (better shown in Figure 2).
A plurality of baffles (better shown in Figures 2 and 3) generally labeled at 23 are longitudinally positioned in passage 16 with respect to the longitudinal axis of trough 12 to join trough 12 and second wall 14. Prefer-ably baffles 23, generally referred to as cross-flow baffles are spaced in passage 16 so as to define a series of longitudinal passageways including central passageway 16a and passageways 16b, 16c adjacent thereto. Each of baffles 23 is provided with an aperture shown at 23a and 23b, to define a gas passage for the flow of steam. These apertures are so arranged to convey the flow of steam in contact with heat exchanging metallic wall 12 in a serpentinous fashion.
For instance, each of the two baffles 23' border-ing central passageway 16a have apertures 23a near downstream wall portion 21 to transfer portions of the flow of steam from central passageway 16a to adjacent passageway 16b.
Similarly, each of baffles 23'' is provided with an aperture 23b near baffles 22 and adjacent upstream wall portion 20 to transfer each of the portions of the flow of steam to adjacent passageway 16c.
In a preferred embodiment, the flow of steam travels in a serpentinous fashion as shown by dashed line 24. In this case, the flow of steam is conveyed from inlet 18 to central passageway 16a by baffles 22 and downstream toward downstream wall portion 21. The steam passes through apertures 23a and travels upstream in passagways 16b ~S~i3 toward upstream wall portion 20. The steam passes through apertures 23b into passageways 16c and travels therein toward outlets l9a and 19b. Thus, baffles 22 and 23 along with apertures 23a and 23b increase the interval of heat exchange between the flow of molten smelt and the flow of steam and thereby increase heat exchange efficiency. If desired, baffles 23 may be radially positioned in passage 16 as shown by dashed lines 25 for defining radial passageways instead of longitudinal passageways.
By utilizing steam as the coolant, we remove the heat energy from the smelt and transfer it to the steam.
Generally, it was common practice to let this heat energy of the smelt be transmitted to the ambient surrounding air etcetera, thereby not making use of this available energy.
In the preferred embodiment, smelt spout 10 is provided with supporting means, one of the ways to support the spout shown at 26a, 26b and 26c, for positioning against the outlet of a delivering smelt device, for instance a recovery boiler, whose outlet sleeve is shown at 27. Other alternatives for supporting spout 10 are also contemplated as is known to those skilled in the art.
A steam nozzle 28 is connected to the superheated steam outlets l9a and l9b. Several alternatives to the steam nozzle 28 may be used as long as they direct the flow of steam in superheated condition toward the flow of smelt and preferably counter-current thereto, During the transfer of a molten smelt using the smelt spout, the flow of smelt is conveyed on one surface of a heat exchanging metallic wall near one end thereof, and is 0 allowed to be displaced to t~le other end of the surface.
~Z358~3 g In a particular embodiment, the smelt is the result-ing product of black liquor combustion to recuperate inorganic materials in smelt form. In this case for instance, the spout transfers the smelt from a recovery furnace to a dissolving tank positioned therebelow.
Other smelts compatible with steam may also be suitable where one wishes to fractionate the flows of smelt with steam.
Typically, the smelt has temperatures ranging from 1800 to 2200F on engaging the heat exchanging surface.
Higher or lower temperatures may be used depending on the nature of the smelt transferred and the nature of the metal of which the spout is constructed.
On the opposite wall of the heat exchanging metallic wall, a tortuous flow of steam is brought into heat transfer relationship therewith.
Preferably, the steam is introduced to the spout in a saturated condition and at a temperature ranging from 375 to 450F. (Higher or lower temperatures may also be used depending upon the temperature of the entering smelt, and of the temperature one wishes the smelt to have upon leaving the spout, and of the nature of the heat exchang-ing surface~. Heat is transferred from the flow of smelt to the flow of steam, thereby bringing the flow of steam to a superheated condition.
At the same time, the heat exchanging metallic wall is cooled along with the flow of smelt, to reduce the heat stressing conditions of the heat exchanging metallic wall.
- The flow of steam thereby obtained in said superheated condition, produces minimum explosive expansion when in ~Z35~63 contac~ with the molten smelt. As a matter of fact, there had been no explosions during the use of the steam cooled spout as they occured in intervals in the past with water cooled spouts and it would appear that these explosions S have now been eliminated.
Having described the invention, modifications will be evident to those skilled in the art without departing from the spirit of the invention, as defined in the appended claims.
FIELD OF THE INVENTION
This invention relates to a steam cooled spout for transfering a molten smelt and to a method of transfering a molten smelt. More particularly, this invention relates to a steam cooled spout for transfering molten smelt such as in chemical recovery furnaces and to a method therefor.
BACKGROUND OF THE INVENTION
In the Pulp & Paper Industry, recovering furnaces are used in order to obtain valuable products from black liquors or from other sources of materials used during the production of pulp and paper. The byproduct of this process is commonly attained in a molten smelt which is highly viscous and at temperatures ranging from 1800 to 2000 F.
In many instances, the molten liquid smelt (herein referred to as "smelt") needs to be transferred. For instance, one may wish to convert it to a white liquor to be reused.
When one wishes such a transfer, spouts are generally used. However, due to the high temperature of the smelt, the spouts need to be cooled or insulated to prevent extreme damage thereto. One example of such spouts is described in United States Patent 3,122,421 as invented by T.G. Gettle, where water is circulated through pipes to cool the spout. Water is generally the well accepted coolant for its economy.
However, this transfer procedure presents both uneconomical and serious hazardous difficulties due to the explosive characteristics of the smelt. Any contact of the smelt with the water or other similar cooling material ~ 3S~3 results in a sudden expansion of the cooling material, thereby causing an explosion.
of a further concern are the extreme conditions of heat and friction inherent in the smelt, which must be withstood in order to provide both hazard-free and economical transfer of smelt.
One method of overcoming this problem has been to cover the spout with refactory lining to insulate against heat while providing a surface to absorb the friction caused by the flowing smelt. It has also been described in United States Patent 4,011,047 as invented by Tremblay, a spout having a refractory lining and in which steam is used to intercept the trajectory of the smelt and to disintegrate the smelt into particles and where the steam is partly heated with the heat derived from the bottom wall of the spout.
This was used, for instance, on recovery furnaces in the Pulp & Paper Industry. Spouts of this nature provided operating periods in keeping with those of the recovery furnace since both employed the same lining. However, such a lining under drastic conditions has a life span in the order of months.
Recovery boiler technology has since advanced to the use of water cooling in lieu of refractory linings which provided substantial improvements in maintenance~free operation time periods. In response, attempts were made to incorporate water cooling of the smelt spout in lieu of the refactory lining therein. However, the water cooled spouts were found to be hazardous since any contact of the smelt with the cooling water caused damaging explosions.
~3~i3 In some instances, the explosions caused a breakup of the spout producing a chain reaction of subsequent larger explosions.
BRIEF DESCRIPTION OF THE PRESENT INVENTION
It is therefore an object of the present invention to provide an improved steam cooled spout having substantially increased maintenance-free operating periods while substantially eliminating and if not, substantially reducing the explosive hazards associated with present spouts, and an improved method of transfering a molten smelt.
Briefly stated, the invention comprises a substant-ially energy saving steam cooled spout offering reduced explosion hazards, comprising a substantially heat resistant heat exchanging metallic wall, defining a spout for receiving and conveying a smelt and contacting said smelt against one surface of said heat exchanging metallic wall, and wherein on the opposite surface of said heat exchanging metallic wall, a second heat resistant wall joins said heat exchanging metallic wall, and deEines with said opposite surface a passage for a flow of steam along said heat exchanging metallic wall, and mounted within said passage a plurality of baffle means joining said heat exchanging metallic wall to said second wall as to define a tortuous path to increase the path of said steam over said heat exchanging metallic wall, to raise the temper-ature of said steam, and said tortuous path boosts said temperature to obtain steam in a superheated condition, while cooling said heat exchanging metallic wall and thereby said smelt, and reducing the stress caused on said heat exchanging metallic wall by said molten smelt, said passage at the outlet end being provided with means fGr directing said flow of steam in said superheated condition into said flow of molten smelt, said steam, in said superheated condition having minimum explosive expansion characteristics, when in contact with said molten smelt.
The invention is also directed to a method of transfering a molten smelt offering reduced explosion hazards comprising: conveying on one surface of a heat exchanging metallic wall, and near one end of said sur ace a flow of molten smelt, allowing said flow of smelt to be displaced to the other end of said surface of said heat exchanging metallic wall, bringing into heat transfer relationship the opposite surface of said heat exchanging metallic wall near said one end to near said other end, a tortuous flow of steam causing heat to be continuously transferred from said flow of smelt to said flow of steam thereby bringing said flow of steam to a superheated condition, while cooling said heat exchanging metallic wall and thereby said smelt, and enabling the temperature of said steam, in said superheated condition to approach the temperature of said smelt to reduce the heat stressing conditions of said heat exchanging metallic wall, and to obtain steam, in superheated condition with minimum explosive expansion, said steam offering reduced explosion hazards when in contact with the molten smelt.
By the term "smelt" used throughout the claims and disclosure, is meant a molten slag in a liquid state.
Examples of preferred smelt include slag obtained from black liquor frorn a recovery furnace. If desired, other ~2~s~3 slags may also be used as long as they are compatible with steam and with the heat resistant heat exchanging metallic wall.
DESCRIPTION OF THE DRAWINGS
A particular embodiment of the present invention will now be described in detail having reference to the accompanying drawinys in which:
Figure 1 is a cross-sectional drawing of a smelt spout.
Figure 2 is an end view of the smelt spout, with respect to line 2-2 in Figure 1.
Figure 3 is a rear sectional view of the smelt spout with respect to lines 3a-3a and 3b-3b of Figure 1.
Figure 4 is a front view of the smelt spout with respect to line 4-4 of Figure 1.
Now, referring to Figure 1, the smelt spout 10 has a conveniently trough-shaped heat exchanging metallic wall 12 (herein referred to as "trough") having a surface 12a (better shown in Figure 2) to receive,confine and convey a flow of smelt shown by dashed lines 13. Other shapes may be used if desired. Surrounding the trough 12 and joined thereto is a second wall 14 for defining with the steam surface 12b of trough 12 (better shown in Figure 2), a passage 16 for a flow of steam. The passage 16 is provided with a steam inlet 18 and superheated steam outlets l9a and l9b.
Closing the upstream and downstream ends of passage 16 are upstream and downstream wall portions 20 and 21 respectively. Positioned with respect to the upstream wall portion 20 are a plura1ity of baffles genera11y shown ~35W3 at 22 to direct the flow of steam from inlet 18 to the passage 16 beneath the central section 12c of trough 12 (better shown in Figure 2).
A plurality of baffles (better shown in Figures 2 and 3) generally labeled at 23 are longitudinally positioned in passage 16 with respect to the longitudinal axis of trough 12 to join trough 12 and second wall 14. Prefer-ably baffles 23, generally referred to as cross-flow baffles are spaced in passage 16 so as to define a series of longitudinal passageways including central passageway 16a and passageways 16b, 16c adjacent thereto. Each of baffles 23 is provided with an aperture shown at 23a and 23b, to define a gas passage for the flow of steam. These apertures are so arranged to convey the flow of steam in contact with heat exchanging metallic wall 12 in a serpentinous fashion.
For instance, each of the two baffles 23' border-ing central passageway 16a have apertures 23a near downstream wall portion 21 to transfer portions of the flow of steam from central passageway 16a to adjacent passageway 16b.
Similarly, each of baffles 23'' is provided with an aperture 23b near baffles 22 and adjacent upstream wall portion 20 to transfer each of the portions of the flow of steam to adjacent passageway 16c.
In a preferred embodiment, the flow of steam travels in a serpentinous fashion as shown by dashed line 24. In this case, the flow of steam is conveyed from inlet 18 to central passageway 16a by baffles 22 and downstream toward downstream wall portion 21. The steam passes through apertures 23a and travels upstream in passagways 16b ~S~i3 toward upstream wall portion 20. The steam passes through apertures 23b into passageways 16c and travels therein toward outlets l9a and 19b. Thus, baffles 22 and 23 along with apertures 23a and 23b increase the interval of heat exchange between the flow of molten smelt and the flow of steam and thereby increase heat exchange efficiency. If desired, baffles 23 may be radially positioned in passage 16 as shown by dashed lines 25 for defining radial passageways instead of longitudinal passageways.
By utilizing steam as the coolant, we remove the heat energy from the smelt and transfer it to the steam.
Generally, it was common practice to let this heat energy of the smelt be transmitted to the ambient surrounding air etcetera, thereby not making use of this available energy.
In the preferred embodiment, smelt spout 10 is provided with supporting means, one of the ways to support the spout shown at 26a, 26b and 26c, for positioning against the outlet of a delivering smelt device, for instance a recovery boiler, whose outlet sleeve is shown at 27. Other alternatives for supporting spout 10 are also contemplated as is known to those skilled in the art.
A steam nozzle 28 is connected to the superheated steam outlets l9a and l9b. Several alternatives to the steam nozzle 28 may be used as long as they direct the flow of steam in superheated condition toward the flow of smelt and preferably counter-current thereto, During the transfer of a molten smelt using the smelt spout, the flow of smelt is conveyed on one surface of a heat exchanging metallic wall near one end thereof, and is 0 allowed to be displaced to t~le other end of the surface.
~Z358~3 g In a particular embodiment, the smelt is the result-ing product of black liquor combustion to recuperate inorganic materials in smelt form. In this case for instance, the spout transfers the smelt from a recovery furnace to a dissolving tank positioned therebelow.
Other smelts compatible with steam may also be suitable where one wishes to fractionate the flows of smelt with steam.
Typically, the smelt has temperatures ranging from 1800 to 2200F on engaging the heat exchanging surface.
Higher or lower temperatures may be used depending on the nature of the smelt transferred and the nature of the metal of which the spout is constructed.
On the opposite wall of the heat exchanging metallic wall, a tortuous flow of steam is brought into heat transfer relationship therewith.
Preferably, the steam is introduced to the spout in a saturated condition and at a temperature ranging from 375 to 450F. (Higher or lower temperatures may also be used depending upon the temperature of the entering smelt, and of the temperature one wishes the smelt to have upon leaving the spout, and of the nature of the heat exchang-ing surface~. Heat is transferred from the flow of smelt to the flow of steam, thereby bringing the flow of steam to a superheated condition.
At the same time, the heat exchanging metallic wall is cooled along with the flow of smelt, to reduce the heat stressing conditions of the heat exchanging metallic wall.
- The flow of steam thereby obtained in said superheated condition, produces minimum explosive expansion when in ~Z35~63 contac~ with the molten smelt. As a matter of fact, there had been no explosions during the use of the steam cooled spout as they occured in intervals in the past with water cooled spouts and it would appear that these explosions S have now been eliminated.
Having described the invention, modifications will be evident to those skilled in the art without departing from the spirit of the invention, as defined in the appended claims.
Claims (7)
1. A substantially energy saving steam cooled spout offering reduced explosion hazards comprising:
a substantially heat resistant heat exchanging metallic wall, defining a spout for receiving and conveying a smelt and contacting said smelt against one surface of said heat exchanging metallic wall, and wherein on the opposite surface of said heat exchanging metallic wall, a second heat resistant wall joins said heat exchanging metallic wall, and defines with said opposite surface a passage for a flow of steam along said heat exchanging metallic wall, and mounted within said passage a plurality of baffle means joining said heat exchanging metallic wall to said second wall as to define a tortuous path to increase the path of said steam over said heat exchanging metallic wall, to raise the temperature of the steam, and said tortuous path boosts said temperature to obtain steam in a superheated condition while cooling said heat exchanging metallic wall and thereby said smelt, and reducing the stress caused on said heat exchanging wall by said molten smelt, said passage at the outlet end being provided with means for directing said flow of steam in said superheated condition into said flow of molten smelt, said steam, in said superheated condition having minimum explosive expansion characteristics, when in contact with said molten smelt.
a substantially heat resistant heat exchanging metallic wall, defining a spout for receiving and conveying a smelt and contacting said smelt against one surface of said heat exchanging metallic wall, and wherein on the opposite surface of said heat exchanging metallic wall, a second heat resistant wall joins said heat exchanging metallic wall, and defines with said opposite surface a passage for a flow of steam along said heat exchanging metallic wall, and mounted within said passage a plurality of baffle means joining said heat exchanging metallic wall to said second wall as to define a tortuous path to increase the path of said steam over said heat exchanging metallic wall, to raise the temperature of the steam, and said tortuous path boosts said temperature to obtain steam in a superheated condition while cooling said heat exchanging metallic wall and thereby said smelt, and reducing the stress caused on said heat exchanging wall by said molten smelt, said passage at the outlet end being provided with means for directing said flow of steam in said superheated condition into said flow of molten smelt, said steam, in said superheated condition having minimum explosive expansion characteristics, when in contact with said molten smelt.
2. The steam cooled spout as defined in claim 1 further comprising an inlet for said steam to enter into said passage near the vicinity where said molten smelt enters in said spout and said outlet end being near the vicinity where said molten smelt exits from said spout.
3. The steam cooled spout as defined in claim 1 wherein said heat exchanging wall is trough-shaped to define a central section and side sections, and including an upstream wall portion for closing the end of said passage in the vicinity where said molten smelt enters in said spout, and a downstream wall portion for closing the end of said passage in the vicinity where said molten smelt exits from said spout and wherein a first portion of said baffles is positioned with respect to said upstream wall portion, cooperating therewith to direct said flow of steam toward the region of said passage positioned beneath said central section of said trough-shaped heat exchanging metallic wall, a second portion of said baffles is alligned in the direction of said flow of smelt to define, in part, a central passage beneath said central section and near one end of each of said second portion of baffles, a gas passage for said steam, said gas passages being so arranged that one gas passage on a given baffle defining said central passage, is near said downstream wall portion and said gas passages on the next adjacent baffles are positioned near the one of said first portion of baffles adjacent said upstream wall portion, whereby said second portion of baffles conveys said flow of steam against said central section of said trough-shaped heat exchanging metallic wall toward said downstream wall portion, divides said flow into portions and contacts each of said portions against each side section of said trough-shaped heat exchanging metallic wall in a serpentinous fashion.
4. The steam cooled spout as defined in claim 1 wherein said heat exchanging metallic wall is trough-shaped and at least a portion of said baffles is radially positioned in said passage with respect to the central axis of said heat exchanging metallic wall, in order that said steam travels in a serpentinous fashion against said heat exchanging metallic wall.
5. A method of transfering a molten smelt offering reduced explosion hazards, comprising conveying on one surface of a heat exchanging metal-lic wall, and near one end of said surface a flow of molten smelt allowing said flow of smelt to be displaced to the other end of said surface of said heat exchanging metallic wall, bringing into heat transfer relationship the opposite surface of said heat exchanging metallic wall near said one end to near said other end a tortuous flow of steam causing heat to be continuously transferred from said flow of smelt to said flow of steam thereby bringing said flow of steam to a superheated condition, while cooling said heat exchanging metallic wall and thereby said smelt and enabling the temperature of said steam, in superheated condition to approach the temperature of said smelt, to reduce the heat stressing conditions of said heat exchanging metallic wall and to obtain steam, in super-heated condition with minimum explosive expansion, said steam offering reduced explosion hazards when in contact with the molten smelt.
6. The method as defined in claim 5 wherein said smelt is the resulting product of black liquor combustion to recuperate inorganic materials in a smelt form, and following said combustion, said spout transfers said smelt from a recovery furnace to a dissolving tank positioned therebelow.
7. The method as defined in claim 5 wherein said flow of molten smelt to convey on said one surface has tempera-tures ranging from 1800 to 2200°F, said steam being fed is saturated and has temperatures ranging from 375 to 450°F.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000479074A CA1235863A (en) | 1985-04-12 | 1985-04-12 | Steam cooled spout |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000479074A CA1235863A (en) | 1985-04-12 | 1985-04-12 | Steam cooled spout |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1235863A true CA1235863A (en) | 1988-05-03 |
Family
ID=4130263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000479074A Expired CA1235863A (en) | 1985-04-12 | 1985-04-12 | Steam cooled spout |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1235863A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995026439A1 (en) * | 1994-03-25 | 1995-10-05 | Asea Brown Boveri Inc. | Smelt spout for a recovery furnace |
-
1985
- 1985-04-12 CA CA000479074A patent/CA1235863A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1995026439A1 (en) * | 1994-03-25 | 1995-10-05 | Asea Brown Boveri Inc. | Smelt spout for a recovery furnace |
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