US3744215A

US3744215A - Method and apparatus for cupola emission control

Info

Publication number: US3744215A
Application number: US00118926A
Authority: US
Inventors: T Barnes
Original assignee: DON BARNES Ltd
Current assignee: DON BARNES Ltd; DON BARNES LTD CA
Priority date: 1971-02-25
Filing date: 1971-02-25
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10
Also published as: CA939145A

Abstract

A cupola emission control system is disclosed which includes a cylindrical cap assembly adapted to be mounted on top of a cupola flue so that gases from the cupola enter the assembly through an opening in the bottom thereof. The top of the cap assembly is defined by a pair of doors adapted to be opened to open the cap to atmosphere. Opposed side wall portions of the cap are provided with openings, one of which is an ambient air opening and the other of which is a mixture outlet opening. Fan means is disposed in a ductway leading to the air inlet opening so that ambient air under positive pressure can be introduced into the cap for dilution and cooling in the cap of gases from the furnace. The outlet opening is connected to a pair of separator units which are serially arranged between the cap housing and an exhaust stack for the system. An exhaust fan is associated with the output side of the second separator leading to the stack in order to induce flow of furnace gases through the system to the stack.

Description

Barnes, Jr.

[451 July 10, 1973' METHOD AND APPARATUS FOR CUPOLA EMISSION CONTROL [75] Inventor: Thomas Donald Barnes, Jr.,

Burlington, Ontario, Canada [73] Assignee: Don Barnes Ltd., Hamilton, Ontario,

Canada [22] Filed: Feb. 25, 1971 21 Appl. No.: 118,926

[52] US. Cl 55/83, 55/257, 26l/D1G. 9 [51] Int. Cl....'. B0111 50/00 [58] Field of Search 55/83, 84, 89, 72, 55/9, 257, DIG. 30; 261/016. 9, 17; 266/16, 17

[56] References Cited UNITED STATES PATENTS 2,729,301 l/l956 Ekstrom, Jr. ..'55/257 2,940,733 6/1960 Umbricht... 55/257 3,382,649 5/1968 Richmond..... 55/84 3,477,203 11/1969 Luge et 55/9 2,618,548 11/1952 Drake 266/17 3,315,444 4/1967 Seversky... 55/257 3,406,012 10/1968 Rahn 55/72 Primary Examiner-Charles N. Hart Attorney-Meyer, Tilberry and Body [57 ABSTRACT A cupola emission control system is disclosed which includes a cylindrical cap assembly adapted to be mounted on top of a cupola flue so that gases from the cupola enter the assembly through an opening in the bottom thereof. The top of the cap assembly is defined by a pair of doors adapted to be opened to open the cap to atmosphere. Opposed side wall portions of the cap are provided with openings, one of which is an ambient air opening and the other of which is a mixture outlet opening. Fan means is disposed in a ductway leading to the air inlet opening so that ambient air under positive pressure can be introduced into the cap for dilution and cooling in the cap of gases from the furnace. The outlet opening is connected to a pair of separator units which are serially arranged between the cap housing and an exhaust stack forthe system. An exhaust fan is associated with the output side of the second separator leading to the stack in order to induce flow of furnace gases through the system to the stack.

22 Claims, 2 Drawing Figures INVENTOR. THOMAS D. BARNES JR.

ATTORNEYS METHOD AND APPARATUS FOR CUPOLA EMISSION CONTROL The present invention relates to furnace emission control systems and, more particularly, to a method and apparatus for cupola emission control.

In furnace systems heretofore known, such as cupola furnace systems, draft effecting arrangements have been employed to control the varying melting processes within the furace and to exhaust furnace gases through particle separating and collecting apparatus to clean the exhaust gases prior to emission thereof into the atmosphere. Such prior art systems may include acap structure disposed atop the furnace flue, and a suc-' tion fan or the like disposed down stream from the cap structure and operated to maintain a desired flow of air through the furnace charge door and into the flue and cap and thence into the separator apparatus and exhaust stack. In certain instances, the prior art system include the provision of a damper controlled opening in the cap to permit the exhaust of furnace gases directly to atmosphere or to permit induced flow of air into the cap structure by the exhaust fan for cooling the exhaust gases as they travel along the path to the separator apparatus and the exhaust stack.

Cupola emission control systems of the above character fail to provide satisfactory furnace process control commensurate with desirable furnace gas emission control. Moreover, the induced cooling air arrangements necessitate the use of expensive high-alloy stainless or refractory-lined take-off ducting from the cap assembly because of the inability of these systems to otherwise accommodate the extremely high emission gas temperatures realized during certain periods of furnace operation. In this respect, the gas temperatures coming from the surface of a charge in the furnace under normal cupola operating conditions is in the range of 450 to 700 F. During a bum-down condition, however, such as at the end of the operating cycle when the charges are allowed to melt down in thecupola resulting in low burden levels, the heat of gases in the cupola flue at the cap will be as high as l,700 to 2,000F and live flames from the furnace may rise in the stack all the way to the cap. With an induced cooling air arrangement of the character heretofore known, air introduced at the cap point through a damper or door controlled opening results in laminar flow of air and furnace gas streams in the take-off pipe or conduit leading from the cap. Such laminar flow continues for a considerable distance in the take off conduit before natural mixing of the air and gases occurs due to the kinetics of gas streams. Thus, the more costly materials mentioned above are required in fabricating the cap and the cap take-off pipe or exhaust ducting in order to handle the high temperatures in these components of the system resulting from the slow mixing of air and hot furnace gases. Moreover, the cap structure itself is disadvantageously subjected to the high temperature conditions of the flue gases and furnace flames. It will be appreciated too that in the systems heretofore known, the slow cooling of furnace gases resulting from laminar flow of air and gas streams results in a relatively high temperature of the'gases when they reach the exhaust fan. Thus, the fan as well as the separator equipment through which the gases pass in traveling toward the fan are disadvantageously subjected to undesirably high temperatures which adversely affect the life thereof. r

In addition to the inability of earlier systems to provide for an adequate amount of cooling of furnace gases and system components, little or no control can be exercised with regard to the total volume of gases and air flowing through the system at a given time or .under furnace operating conditions. Such control is highly desirable and advantageous in that for a range of operating temperatures for a given furnace, more efficient and effective emission temperature control can be achieved when the total gas and air volume in the system can be accurately maintained regardless of changing operating conditions within the furnace. In the past, cooling air has been introduced with little or no control of thevolume thereof.

The emission control system of the present invention advantageously overcomes the drawbacks of the prior art arrangements including those specifically mentioned above and, in this respect, provides a constant volume emission control system which is capable of handling a wide range of temperatures and initial gas volumes coming from the melting zone of a cupola so that absolute temperature control of gases entering the exhaust stack can be achieved. In the system of the present invention, the temperature of gases emitted from the furnace is controlled immediately at the cap in a manner whereby, regardless of the wide temperature range of these gases in the flue of from about 450 to 2,000 F, the exhaust stack temperatures can be maintained below about 650 F. This is achieved by reducing the temperature of the furnace gases at the cap to a range of about 600 to 700 F even when the furnace gases entering the cap are in the upper vicinities of the 450 to 2,000 F range. It will be appreciated that such control of the temperatures of the furnace gases at the cap advantageously eliminates the necessity of employing the costly materials heretofore required for the cap take-off ducting in order to handle the high temperatures of the gases. Moreover, the temperature control protects the exhaust fan and separator equipment and provides for more accurate and efficient cupola operation.

The foregoing advantages are achieved in the present invention by positively forcing ambinet air directly into the cap structure with a high velocity so that the hot particle laden furnace gases entering the cap area are immediately mixed with the air and are thereby subjected to considerable cooling and dilution by the air before leaving the cap. As is well known in cupola fur nace operation, air is admitted to the flue through the charging door in a controlled volume for mixture with the furnace gases from the melting area of the furnace as they rise in the flue. As used herein, the term furnace gases is intended to include draft air and the gases emitted directly from the melting area of the furnace. The ambient air forced into the cap is a pre-calculated amount of air designed to provide a constant volume for agive'n furnace size. The forced air is introduced into the cap area under high velocity in order to achieve immediate furnace gas-air mixing in the cap. This high velocity charge of air in addition to cooling the furnace gases, provides for diluting the particle laden furnace gases and for providing temperature protection for the cap structure even in the most extreme high temperature operating conditions of the cupola.

' Moreover, the forced dilution and constant volume operating characteristics of the system of this invention operate to maintain carbon monoxide in the exhaust gases at a desirably low level and to provide for more efficient separation of the particles from the furnace gases, thus to advantageously reduce the pollution level of gases exhausted to atmosphere.

It is to be noted too that the high velocity forced air addition at the cupola cap area, by maintaining a cap exhaust temperature level in the range of about 600 to 700 F, protects the downstream equipment including the exhaust fan and separator components from the adverse affectsof high temperature and eliminates the necessity of any external cooling means for the upstream equipment and ductwork such as cooling water which has been employed in the past. Use of cooling water disadvantageously causes corrosion of metallic components in the system, is subject to freezing problems during cold weather and involves the use of expensive flow controlling devices. A further advantages of the system of the present invention is the fact that by maintaining constant gas-air volumes, constant efficiency in particle collection by the separating equipment is realized independent of the melt rate of the furnace.

Accordingly, it is an outstanding object of the present invention to provide a furnace emission control system which advantageously operates to cool and dilute hot particle ladden furnace gases, thus to protect system equipment from adverse temperatures and more efficiently provide for separation of particles from the gases and reduce the level of pollutants therein and thereby advantageously reduce the pollution level and temperature of gases ultimately exhausted from the system.

A further object of the present invention to to provide a furnace emission control system adapted to handle a wide range of exhaust temperatures and gas volumes coming from the operating zone of a furnace in a manner whereby absolute temperature control of the gases entering the exhaust stack of the system is achieved.

Another object of the invention is to provide a furnace emission control system in which high velocity force air is added to the furnace gases to the top of the furnace flue to achieve immediate gas diluting and cooling, whereby absolute temperature control of gases entering the exhaust stack can be achieved.

Another object is the provision of a furnace emission control system of the character mentioned wherein a constant volume of high velocity forced air is added to furnace gases to achieve cooling of furnace gases to a desired low exhaust temperature and to maintain a constant gas-air volume in the system.

A further object of the present invention is to provide a furnace emission control system in which a cap assembly of the system receives high velocity ambient air under positive pressure directly thereinto to provide temperature protection for the cap assembly even under the most extreme high temperature operating conditions of the furnace.

Yet another object of the present invention is to provide a furnace emission control system in which the necessity for the use of high temperature resistance materials heretofore required is advantageously eliminated.

Still another object of the present invention is the provision of a method of cooling cupola furnace emission gases in a manner to achieve greater temperature reduction of the gases leaving the cupola flue than heretofore possible.

Still a further object is to provide a method of treating cupola emission gases to facilitate cooling and particle removal therefrom with greater efficiency than heretofore known.

Still another object is the provision of a furnace emission control system including a cap structure adapted to be mounted on top of an existing furnace flue and defining a chamber into which furnace gases can flow and in which the gases are cooled and diluted by introduction of a high velocity stream of air under positive pressure directly into the cap, and which cap is provided with movable opening means to permit direct exhaustion of furnace gases to atmosphere.

Other objects will in part be obvious and in part more fully pointed out hereinafter in conjunction with the description of the drawing which illustrates a preferred embodiment of the invention and in which:

FIG. 1 is aside elevation view of the emission control system of the present invention in its entirety; and

FIG. 2 is a plan view section of the cap structure of the system taken along the line 2-2 in FIG.- 1.

Referring now in particular to the drawing, there is illustrated in FIG. l a cupola 10 including a refractory lined, steel jacket flue 11, a charging door or opening 12 and a pressure air trunk 13. Trunk 13 is supplied with air from a pipe 14 which in turn receives air under pressure in a well known manner from any suitable source. As is well known to those skilled in the art of cupola furnaces, materials to be treated therein are introduced through the charging door, and combustion is maintained by an air blast through tuyers extending inwardly from the air trunk 13 at the bottom of the cupola. During operation of the cupola a controlled draft enters the charging door for flow upwardly therein with gases from the furnace. Simultaneous control of the combustion air and the suction draft facilitates effective regulation of the combustion process within the eupola. In accordance with known practice, a gas fired after-burner 15 may be provided in the flue of the cupola to eliminate carbon monoxide gas and to reduce odor emission from the cupola.

In accordance with the present invention, furnace emission control apparatus is provided which includes cap means 16 including a cylindrical housing 17 adapted to be suitably mounted on the furnace flue 11. Housing configurations other than cylindrical could, of course, be employed. The emission control apparatus further includes separator means 18 disposed between exhaust conduit means 119 leading from the cap housing and an exhaust stack 20. Conduit means 159 may be a non-corroding steel. Separator means 18 preferably is defined by serially arranged separator units 21 and 22, separator 21 being a heavy particle collector and separator 22 preferably being a cyclone type collector. The specific separator structure is not pertinent to the pres ent invention, and any suitable separator or precipitator apparatus may be employed. A motor operated exhaust fan 23 is disposed on the output side of separator 22, and the output of the exhaust fan leads to exhaust stack 20 through exhaust duct 24.

The cylindrical cap housing 17 includes, as illustrated in FIGS. 1 and 2, a bottom opening 25, cylindrical sidewall means 26 and movable closure means 27 overlying sidewall means 26 and defining a cap chamber 28 therewith. Cap sidewall means 26 is defined by a steel shell 26a and refractory lining 26b and thus, in effect defines an extension of flue ll. Thus, the cap section could be integral with stack 11. Opening defines a gas inlet leading into chamber 28 from flue 22. Opposed

cylindrical openings

29 and 30 are provided in wall means 26 and respectively define an air inlet and a mixture outlet for the cap housing. Cylindrical'air inlet conduit means 31, preferably of steel construction, extends laterally'outwardly from sidewall means 26 in surrounding relationship with regard to opening 29 in the sidewall means. Conduit means 31 includes a conical wall portion 32 disposed between the entrance end 33 of the conduit means and sidewall means 26. Air pump means, here in the form of a motor driven fan 34, is disposed in conduit means 31, and baffle means is disposed in the conduit means between fan 34 and opening 29 in sidewall means 26. Preferably baffle means 35 is in the form of a cone-shaped component disposed in conduit means 31 with the smaller diameter end thereof facing toward the fan. Conical wall portion 32 of conduit means 31 conforms substantially to the contour of cone-shaped baffle 35. The cone may, if desired, be mounted to be axially reciprocated relative to conduit means 31 thus to increase and decrease the space 36 between baffle 35 and conical wall portion 32 to facilitate varying the velocity of inlet forced air.

Opening 30 in sidewall means 26 defining the mixture outlet is surrounded by cylindrical, tapered ductwork section 37, extending laterally from sidewall means 26 and suitably connected at its outer end 38 to conduit 19. Ductwork section 37 preferably is unlined stainless steel. The axes of air inlet opening 29 and mixture outlet opening 30 are substantially parallel and, although the openings are preferably in opposed portions of sidewall means 26 of the cap housing, it is to be clearly understood that the openings could be otherwise oriented relation to the housing. It will be further noted in the preferred embodiment that the axes of air inlet opening 29 and mixture outlet opening 30 are disposed substantially perpendicular to the axis of gas inlet opening 25. It will be appreciated, however, that other angular relationships can be employed, still within the present invention.

Movable closure means 27 is defined in the preferred embodiment by a pair of steel door elements 39 and 40 hingedly associated with cap housing 17 by means of suitable

corresponding hinge assemblies

41 and 42. Portions 39a and 40a of door elements 39 and 40, respectively, extend laterally beyond the corresponding hinge assemblies to define counterweight means adapted to bias the door elements toward an open disposition as depicted by broken lines in FIG. 1. The latter arrangement is defined by pulleys 43 rotatably supported by sidewall means 26 of housing 17 and cables 44 suitably attached to the respective doors and trained about the corresponding pulleys to a common link element 45. Link 45 is in turn connected to one end of cable 46 having its opposite end suitably interconnected with the piston rod of an air cylinder 47. Air cylinder 47 is charged to pull downwardly on cable 46, thus to maintain doors 39 and 40 in a closed disposition. The air cylinder may be manually actuated to release the doors for movement thereof to the open position under the influence of the counterweight portions 39a and 40a thereof. Further, cylinder 47 may be adverse condition controlled in order to provide for automatic release of the doors in response to an adverse condition which dictates that the furnace gases should be exhausted directly to atmosphere. For example, the

cylinder may be controlled by a thermostat 48 in duct 24 to open the cap doors in response to undesirably high temperature of exhaust gases.

Fan 34 is adapted to draw ambient air into conduit means 31 and to force this air under positive pressure directly into chamber 28 of the cap housing. This ambient air mixes and comingles with the hot, particle laden flue gases immediately in the chamber of the cap housing to cool and dilute the furnace gases to a substantially lower temperature than the temperature thereof upon entering the chamber through gas inlet 25. This cooling and diluting in the chamber is made'possible by a high velocity flow of a predetermined and controllable volume of ambient air directly into the chamber. Baffle means 35 provides for introducing the cooling and diluting air laterally into the chamber in a desired flow pattern. The preferred flow pattern is an annular pattern such as that which is provided by the conical configuration of baffle 35. Such a pattern provides for a portion of the ambient inlet air to pass adjacent the underside of door elements 39 and 40, thus to cool the door elements and protect these elements against the adverse effects of the high temperature furnace gases enterring the cap housing. Further, the annular pattern of flow of ambient air provides for a portion of the air to intercept the furnace gases immediately as they enter the bottom of chamber 28 of the housing, thus to promptly initiate the cooling and diluting of the gases by the ambient air. The direction of inlet air flow, transverse to the direction of the gas inlet flow to the chamher, is also desirable in that it effects a condition of turbulance in the chamber by which a more rapid and thorough mixing, cooling and diluting of the particle laden gases is achieved. It will be appreciated that fan 34 can be positioned other than in axial alignment with duct means 31. For example, the fan can be vertically oriented and the flow therefrom directed into the horizontal duct 31 by suitable elbow duct means.

Although the cone-shaped baffle 35 is preferred it will be readily understood that other baffle means may be employed, such as for example an annular plate baffle or vein elements disposed in conduit means 31. it will be appreciated too that with such other types of baffle means, the baffle elements could be made to be readily adjustable to provide the desired direction of flow for the inlet air.

Fan 34 is driven by an electric motor or other source of power and is adapted to positively pump a given constant volume of air into the cap chamber to achieve the desired cooling effect. The volume of forced air introduced is precalculated dependent on furnace size, and fan 34 is driven continuously during furnace operation to deliver the calculated volume of ambient air.

Exhaust fan 23 is, of course, operated continuously during furnace operation and is of a capacity depending on furnace size, thus to assure a proper draft through the charging door and a constant volume of furnace gas flow upwardly to the cap and thence through the separator apparatus to the stack. It should be distinctly understood at this point, however, that although the volume of ambient air forced into the cap chamber is a function of the total volume of gases and air in the system, including the furnace gases and draft air, the amount of ambient air input is precalculated to correspond with the operating conditions and requirements of a given cupola but does not in and of itself materially effect the gas-air flow induced by the exhaust fan. The ambient air fan, in other words, is not relied upon to cause gas-air flow through the system to the exhaust stack.

As mentioned hereinabove, the specific volume of forced air addition and the volume of gases and air drawn through the system by the exhaust fan are dependent in each instance on furnace size. Once established, however, these volumes remain constant for a given furnace throughout furnace operation and during varying temperature conditions of such operation. De-

. pending on furnace size, forced air addition generally will be in the range of 4,000 to 12,000 c.f.m. The exhaust fan will also be operated in accordance with furnace size and generally will induce gas-air flow through the system in the range of 28,000 to l l5,000 c.f.m. The present invention provides for constant volume operation of the system, and as a result of constant volume addition of high velocity ambient air, exhaust stack temperatures are maintainable at below about 600 F even during periods of operation during which furnace gases entering the cap area approach 2,000 F. Moreover, forced addition of ambient air under high velocity and pattern control reduces furnace gas temperatures approaching 2,000 F in the flue immediately in the cap area to a low range of 600 to 700 F which advantageously avoids the necessity of using refractory lined ductwork on the outlet side of the cap. Furnace systems simply relying on induced air addition experience a gas temperature in the cap area several hundred degrees above the 600 to 700F and thus require the use of expensive refractory lined ductowrk to handle the high temperature gases.

The apparatus of the present invention has been described hereinabove in conjunction with a preferred structural embodiment. Various changes may be made in this embodiment, however, without departing from the intended spirit and scope of the present invention as defined in the appended claims.

I claim:

1. Apparatus for use in an emission control system for a furnace having a flue comprising, a housing at the upper end of said flue, said housing having a gas inlet, an air inlet and a mixture outlet, said housing being adapted to receive, hot particle laden gases from said furnace, flow inducing means for drawing said furnace gases into said housing through said gas inlet, conduit means surrounding said air inlet, and air pump means in said conduit means and spaced from said air inlet for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet.

2. Apparatus of the character set forth in claim ll, wherein the axes of said air inlet and said gas inlet are substantially perpendicular to one another.

3. Apparatus of the character set forth in claim 2 wherein the axis of said mixture outlet is substantially parallel to the axis of said air inlet.

4. Apparatus for use in an emission control system for a furnace having a flue comprising, a housing at the upper end of said flue, said housing having a gas inlet, an air inlet and a mixture outlet, said housing being adapted to receive hot, particle laden gases from said furnace, flow inducing means for drawing said furnace gases into said housing through said gas inlet, and air pump means for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, conduit means surrounding said air pump means and air inlet, and means within said conduit means for controlling the path of air flow into said housing.

5. Apparatus of the character set forth in claim 4, wherein said means within said conduit means'is baffle means disposed between said air pump means and air inlet.

6. Apparatus for use in a furnace emission control system comprising, a housing having a gas inlet, an air inlet and a mixture outlet, said housing being adapted to receive hot, particle laden gases from said furnace, flow inducing means for drawing said furnace gases into said housing through said gas inlet, an air pump for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, conduit means surrounding said air pump and air inlet, and baffle means within said conduit means between said air pump and air inlet, said baffle means' being cone-shaped and disposed in said conduit means with the smaller diameter end thereof facing toward said air pump, said conduit means including a conical wall portion surrounding said cone-shaped baffle means and radially spaced therefrom to define an annular passageway for directing said air into said housing in an annular path.

7. Apparatus of the character set forth in claim 6, wherein said cone-shaped baffle means is axially adjustable relative to said conduit means to selectively increase or decrease the radial space between the baffle means and conical wall portion of said conduit means, thus to vary the size of said annular passageway and vary the velocity of air flow into said housing.

8. Apparatus of the character set forth in claim 1, and further including exhaust stack means, means for directing the flow of said cooled diluted furnace gases from said mixture outlet to said exhaust stack means.

9. Apparatus of the character set forth in claim 8, wherein said means for directing flow of said cooled diluted furnace gases includes serially arranged separator means for separating particles from said cooled diluted gases, said separator means being disposed between said gas outlet and said exhaust stack means, and said flow inducing means being exhaust fan means between said separator means and said stack means. I

10. Apparatus for use in a furnace emission control system comprising a cap housing mountable on top of a furnace flue and including side wall means and movable closure means, the bottom of said housing being open to said flue to define a gas inlet to said housing, said side wall means having opposed air inlet and mixture outlet openings therein, said housing being adapted to receive hot, particle laden gases from said furnace flue through said gas inlet, flow inducing means for drawing said furnace gases into said housing through said gas inlet, conduit means surrounding said air inlet, and air pump means in said conduit means and spaced from said air inlet for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet,

to said flue to define a gas inlet to said housing, said sidewall means having opposed air inlet and mixture outlet openings therein, said housing being adapted to receive hot, particle laden gases from said furnace flue through said gas inlet, flow inducing means for drawing said furnace gases into said housing through said gas inlet, an air pump for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, said 15. Apparatus of the character set forth in claim 10, wherein said closure means is a pair of doors biased toward an open disposition relative to said housing, and means releasably retaining said doors in a closed disposition against said bias.

16. Apparatus of the character set forth in claim 15, wherein said releasable retaining means is both manually operable and adverse condition responsive.

17. Apparatus of the character set forth in claim 12, and further including exhaust stack means, and means for directing the flow of said cooled diluted furnace gases from said mixture outlet to said exhaust stack means.

movable closure means being operable to open the interior of said housing to atmosphere, conduit means surrounding said air pump means and said air inlet, and means within said conduit means for controlling the path of air flow into said housing.

13. Apparatus for use in a furnace emission control system comprising a cap housing mountable on a furnace flue and including sidewall means and movable closure means, the bottom of said housing being open to said flue to define a gas inlet to said housing, said sidewall means having opposed air inlet and mixture outlet openings therein, said housing being adapted to receive hot, particle laden gases from said furnace flue through said gas inlet, flow inducing means for drawing said furnace gases into said housing through said gas inlet, an air pump for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, said movable closure means being operable to open the interior of said housing to atmosphere, conduit means surrounding said air pump and said air inlet, and means within said conduit means for controlling the path of air flow into said housing, said means within said conduit means being baffle means disposed between said air pumpand air inlet to direct said air into said housing in an annular path, a portion of which air flows in cooling relationship with the underside of said closure means.

14. Apparatus of the character set forth in claim 13, wherein said bafi'le means is cone-shaped means disposed within said conduit means with the smaller diameter end thereof facing toward said air pump, said conduit means including a conical wall portion surrounding said cone-shaped baffle means and radially spaced therefrom to define an annular passageway therebetween.

18. Apparatus of the character set forth in claim 17, wherein said means for directing flow of said cooled diluted furnace gases includes serially arranged separator means for separating particles from said cooled diluted gases, said separator means being disposed between said gas outlet and said exhaust stack means, and said flow inducing means being exhaust fan means between said separator means and said stack means.

19. A method of cooling cupola furnace gases in a eupola emission system including a flue having an outlet end, a chamber at the outlet end of said flue, an exhaust stack, duct means including take-off ducting from said chamber, and means to induce furnace gases to flow from said cupola flue through said chamber and duct means to said exhaust stack, said method comprising forcing ambient air under positive pressure directly into said chamber and into co-mingling relationship with said furnace gases in said chamber to cool said furnace gases in said chamber and reduce the temperature of said gases sufficiently to provide temperature protection for said chamber and take-off ducting.

20. The method of claim 19, and forcing said ambient air into said chamber at a constant volume.

21. A method of treating hot particle laden cupola furnace gases in a cupola emission system including a flue having an outlet end, a chamber at the outlet end of said flue, an exhaust stack, particle separator means between said chamber and exhaust stack and duct means between said chamber and separator means and including take-off ducting from said chamber, said method including inducing furnace gas flow through said flue, chamber, duct means and separator means to said exhaust stack, and forcing ambient air under positive pressure directly into said chamber and into comingling relationship with said furnace gases in said chamber to cool and dilute said gases prior to flow thereof from said chamber to said separator means and exhaust stack and to reduce the temperature of said gases in said chamber sufficiently to provide temperature protection for said chamber and take-off ducting.

22. The method of claim 21, and maintaining the flow rate of induced flow at a constant volume, and forcing said ambient air into said chamber at a constant volume.

Claims

2. Apparatus of the character set forth in claim 1, wherein the axes of said air inlet and said gas inlet are substantially perpendicular to one another.
3. Apparatus of the character set forth in claim 2 wherein the axis of said mixture outlet is substantially parallel to the axis of said air inlet.
4. Apparatus for use in an emission control system for a furnace having a flue comprising, a housing at the upper end of said flue, said housing having a gas inlet, an air inlet and a mixture outlet, said housing being adapted to receive hot, particle laden gases from said furnace, flow inducing means for drawing said furnace gases into said housing through said gas inlet, and air pump means for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, conduit means surrounding said air pump means and air inlet, and means within said conduit means for controlling the path of air flow into said housing.
5. Apparatus of the character set forth in claim 4, wherein said means within said conduit means is baffle means disposed between said air pump means and air inlet.
6. Apparatus for use in a furnace emission control system comprising, a housing having a gas inlet, an air inlet and a mixture outlet, said housing being adapted to receive hot, particle laden gases from said furnace, flow inducing means for drawing said furnace gases into said housing through said gas inlet, an air pump for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, conduit means surrounding said air pump and air inlet, and baffle means within said conduit means between said air pump and air inlet, said baffle means being cone-shaped and disposed in said conduit means with the smaller diameter end thereof facing toward said air pump, said conduit means including a conical wall portion surrounding said cone-shaped baffle means and radially spaced therefrom to define an annular passageway for directing said air into said housing in an annular path.
7. Apparatus of the character set forth in claim 6, wherein said cone-shaped baffle means is axially adjustable relative to said conduit means to selectively increase or decrease the radial space between the baffle means and conical wall portion of said conduit means, thus to vary the size of said annular passageway and vary the velocity of air flow into said housing.
8. Apparatus of the character set forth in claim 1, and further including exhaust stack means, means for directing the flow of said cooled diluted furnace gases from said mixture outlet to said exhaust stack means.
9. Apparatus of the character set forth in claim 8, wherein said means for directing flow of said cooled diluted furnace gases includes serially arranged separator means for separating particles from said cooled diluted gases, said separator means being disposed between said gas outlet and said exhaust stack means, and said flow inducing means being exhaust fan means between said separator means and said stack means.
10. Apparatus for use in a furnace emission control system comprising a cap housing mountable on top of a furnace flue and including side wall means and movable closure means, the bottom of said housing being open to said flue to define a gas inlet to said housing, said side wall means having opposed air inlet and mixture outlet openings therein, said housing being adapted to receive hot, particle laden gases from said furnace flue through said gas inlet, flow inducing means for drawing said furnace gases into said housing through said gas inlet, conduit means surrounding said air inlet, and air pump means in said conduit means and spaced from said air inlet for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, and said movable closure means being operable to open the interior of said housing to atmosphere.
11. Apparatus of the character set forth in claim 10, wherein said means for forcing ambient air under pressure through said air inlet is an air pump.
12. Apparatus for use in a furnace emission control system comprising a cap housing mountable on a furnace flue and including side wall means and movable closure means, the bottom of said housing being open to said flue to define a gas inlet to said housing, said sidewall means having opposed air inlet and mixture outlet openings therein, said housing being adapted to receive hot, particle laden gases from said furnace flue through said gas inlet, flow inducing means for drawing said furnace gases into said housing through said gas inlet, an air pump for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture outlet, said movable closure means being operable to open the interior of said housing to atmosphere, conduit means surrounding said air pump means and said air inlet, and means within said conduit means for controlling the path of air flow into said housing.
13. Apparatus for use in a furnace emission control system comprising a cap housing mountable on a furnace flue and including sidewall means and movable closure means, the bottom of said housing being open to said flue to define a gas inlet to said housing, said sidewall means having opposed air inlet and mixture outlet openings therein, said housing being adapted to receive hot, particle laden gases from said furnace flue through said gas inlet, flow inducing means for drawing said furnace gases into said housing through said gas inlet, an air pump for forcing ambient air under positive pressure directly into said housing through said air inlet for said air to mix with, cool and dilute said gases in said housing, said flow inducing means drawing said cooled diluted gases through said mixture ouTlet, said movable closure means being operable to open the interior of said housing to atmosphere, conduit means surrounding said air pump and said air inlet, and means within said conduit means for controlling the path of air flow into said housing, said means within said conduit means being baffle means disposed between said air pump and air inlet to direct said air into said housing in an annular path, a portion of which air flows in cooling relationship with the underside of said closure means.
14. Apparatus of the character set forth in claim 13, wherein said baffle means is cone-shaped means disposed within said conduit means with the smaller diameter end thereof facing toward said air pump, said conduit means including a conical wall portion surrounding said cone-shaped baffle means and radially spaced therefrom to define an annular passageway therebetween.
15. Apparatus of the character set forth in claim 10, wherein said closure means is a pair of doors biased toward an open disposition relative to said housing, and means releasably retaining said doors in a closed disposition against said bias.
16. Apparatus of the character set forth in claim 15, wherein said releasable retaining means is both manually operable and adverse condition responsive.
17. Apparatus of the character set forth in claim 12, and further including exhaust stack means, and means for directing the flow of said cooled diluted furnace gases from said mixture outlet to said exhaust stack means.
18. Apparatus of the character set forth in claim 17, wherein said means for directing flow of said cooled diluted furnace gases includes serially arranged separator means for separating particles from said cooled diluted gases, said separator means being disposed between said gas outlet and said exhaust stack means, and said flow inducing means being exhaust fan means between said separator means and said stack means.
19. A method of cooling cupola furnace gases in a cupola emission system including a flue having an outlet end, a chamber at the outlet end of said flue, an exhaust stack, duct means including take-off ducting from said chamber, and means to induce furnace gases to flow from said cupola flue through said chamber and duct means to said exhaust stack, said method comprising forcing ambient air under positive pressure directly into said chamber and into co-mingling relationship with said furnace gases in said chamber to cool said furnace gases in said chamber and reduce the temperature of said gases sufficiently to provide temperature protection for said chamber and take-off ducting.
20. The method of claim 19, and forcing said ambient air into said chamber at a constant volume.
21. A method of treating hot particle laden cupola furnace gases in a cupola emission system including a flue having an outlet end, a chamber at the outlet end of said flue, an exhaust stack, particle separator means between said chamber and exhaust stack and duct means between said chamber and separator means and including take-off ducting from said chamber, said method including inducing furnace gas flow through said flue, chamber, duct means and separator means to said exhaust stack, and forcing ambient air under positive pressure directly into said chamber and into co-mingling relationship with said furnace gases in said chamber to cool and dilute said gases prior to flow thereof from said chamber to said separator means and exhaust stack and to reduce the temperature of said gases in said chamber sufficiently to provide temperature protection for said chamber and take-off ducting.
22. The method of claim 21, and maintaining the flow rate of induced flow at a constant volume, and forcing said ambient air into said chamber at a constant volume.