US2498979A - Water separator silencer - Google Patents

Description

Feb. 28, 1950 R. B. BOURNE 2,493,979

WATER SEPARATOR SILENCER Filed Sept. 18, 1943 Sheets-Sheet 1 Feb. 28, 1950 BOURNE 2,498,979

WATER SEPARATOR SILENCER Filed Sept. 1.8. 1 943 4 Sheets-Sheet 2 INVENTQR Rom/m fl. BUMP/YE Vila av 7 ATTO EYS Feb. 28, 1950 R. B. BOURNE 7 2,498,979

WATER SEPARATOR SILENCER Filed Sept. 18, 1945 law. JQJQ ATTOR EYS Feb. 28, 1950 R. B. BOURNE 2,498,979

WATER SEPARATOR SILENCER Filed Sept. 18, 1945 4 Sheets$heet 4 INVENTOR Rain/w B. 300mm Patented F eb. 28, 1950 UNITED STATES PATENT OFFICE WATER SEPARATOR SILENCER Roland B. Bourne, West Hartford, Conn, assignor to The Maxim Silencer Company, Hartford, Conn, a corporation of Connecticut Application September 18, 1943, SerialNo. 502,906

24 Claims.

The present invention relates to devices for silencing the exhausts of internal combustion engines where a high degree of silencing, absolute freedom from sparks and entrained water in the exhaust, and absence of a visible exhaust are of the utmost importance. Such requirements are met with, for example, on board ship, where sparks must be avoided not only from their fire hazard but because their visibility might disclose the position of a ship under wartime conditions. Entrained water in the exhaust is to be avoided since it may settle upon parts of the ships equipment and cause trouble in numerous ways. Even if the entrained water is removed, water vapor in the exhaust may under proper atmospheric conditions form a so-called plume visible at a considerable distance and interfering with gunnery sighting. In accordance with the present invention these difliculties are avoided and a clean, dry

"exhaust secured which may be led over the side or up the stack at the option of the ship designer.

It has been common to employ water commingled with the exhaust to quench sparks and to assist in the silencing action by mechanical action as well as by cooling the gas. In ordinary installations it has not been necessary to remove this water from the exhaust. With the exacting requirements noted above it is necessary, however to remove all entrained water and to render any water vapor in the exhaust invisible. I have found that if the stream of commingled exhaust gas and water is directed against a screen spaced from a wall of the silencer or other enclosure,

and if certain precautions noted below are taken,

practically complete separation of gas and water is instantaneously effected, there being no tendency to form a spray by impact. The process may be repeated if necessary to remove what residual entrained water may still be in the gas. A preferred way is to direct the exhaust stream against the concave side of a dished header standing in a vertical plane, a screen of perforated metal or wire screening being spaced a short distance from the header. It is also preferable to locate the exhaust near the top of the header, as in this instance the water will flow downwardly in a relatively quiet stream.

I have also found that, after the removal of entrained water, the tendency of residual water vapor to form a plume may be avoided by reheating the exhaust gas. This seems to have the effect of preventing the association of water vapor into particles of visible size until they have been dispersed into the air sufliciently so that they are 1 either re-vaporized or are sufficiently separated so as to form no visible cloud eflect. Reheating may be accomplished in various ways, as by transfer of heat from the outside of the inlet pipe to the exhaust gases; by dividing the incoming gas into two parts, the smaller of which is separately silenced and mixed with the exhaust from the main water-flooded silencer; or by directly heating the exhaust by the use of electrical heating elements or the like.

For a more detailed description of the invention reference is made to the drawings, in which Fig. 1 shows a median section of a preferred embodiment of the invention with the casing broken away;

Fig. 2 shows a plan view of the device of Fig. 1 with the main casing broken away;

Fig. 3 shows a section on line 33 of Fig. 1;

Fig. 4 shows a cut-away perspective view of the device of Figs. 1, 2, and 3 turned end for end;

Fig. 5 shows a median section of another embodiment of the invention;

Fig. 6 shows a plan View of Fig. 5 with the casing broken away;

Fig. 7 shows a section on line 1-1 of Fig. '5;

Fig. 8 shows a cut-away perspective View of the device of Figs. 5, 6, and I;

Figs. 9 and 10 show a side elevation and an end view with the casing broken away, of a device similar to that of Fig. 1 but provided with gas re-heating vanes;

Fig. 11 shows the device of Fig. 1 with a hot gas by-pass and silencer in the outlet chamber;

Fig. 12 shows a water separating silencer with an external dry-type reheating silencer;

Figs. 13 and 14 are a fragmentary side view and an end view of a silencer illustrating the adaptation of an electrical heating unit to the iail pipe of a silencer to prevent plume formaion;

Figs. 15 and 16 are generally similar to Figs. 1 and 3 but show an alternative manner of providing communication between the two silencer chambers; and 1 Figs. 16 to 19 are diagrammatic elevations and Fig. 20 is a bottom plan illustrating preferred methods of securing water drainage from the silencer.

The form of silencer shown in Figs. 1 to 4 consists of a generally cylindrical casing 10 having end headers H and 12, which are preferably slightly dished outwardly, and an intermediate header 13 which divides the interior of the casing through the outlet chamber l5, and extends through a considerable portion of the inlet chamber I 4 to open at a point preferably about one and a half pipe diameters from the header H. A water connection l9 permits the introduction of water from the cooling system of the engine into the conduit [6 at a point along its length which as shown is near the intermediate header l3 in the chamber [4. The water may be introduced in any desired manner, although spraying it into the conduit [6 produces better cooling and thus a better silencing action as well as lower back pressure. This position forintroduction of the cooling water is chosen because it permits of a relatively long run of conduit wherein the water and gases are admixed, and at thesame time permits that portion of the conduit which passes through the chamber l5 to remain as hot as possible for reheating the gases during their reverse passagethrough chamber l5.

'The combined gas and water dischargev from the open end of the.conduit l6 strikesthe end header H. .To assist; in separating the Water from the gas in the chamber 14, there is positionedan anti-splash plate which is preferably made of perforated metal, although various wire screening, spaced horizontal grill plates, honeycomb grill work, and the like are effective in preventing undue splashing in this chamber. Where permissible for reasons of strength and freedom from clogging, sheet metal having perforations /8" diameter ,on centers is prefarable; but particularly on larger installations other typesof perforated metal maybe used, such as /2" diameterfperforations on-%" centers. The anti-splash plate20 is preferably positioned about one-fifth pipe diameter away from the header ll. Most of the entrained water, upon passing through the screen and impinging upon this header, falls to the bottom of the chamber l4. To prevent further splashing when the water hits the bottom of the casing, there may be providedanother anti-splash plate 21, positioned above the bottom of the casing II]. In large installations, this plate may be omitted, since a large chamber in itself has a separating action. The natural tendencyis ;for the; separated water to travel toward the-header 13 where it passes into the drain 22. Drains should; of course be located at points of the, chambers where there is a natural tendency of; the water to collect. The chamber l laccomplishes over 99 per cent of the separation I Connecting the chamber l4 and the outlet chamber it are open ended conduits 23 which pierce the header I3. These conduits, as well as the conduitl6, are positioned as near to the top of the casing as practicable, since I have found that this feature is ofimportance in the,

matter of water separation- The conduits 23 extend from a plane inadjacency to the header H, but removed therefrom preferably about two pipe diameters, through the header l3 and discharge into the chamber IS in a manner similar to the discharge of the conduit [6 into the chamber M. The now cooled exhaust gases and whatever residual entrained water they contain impinge upon the end header l2 and its anti-splash 4 caution against spray entering the conduit through them.

The exhaust gas now passes to atmosphere through paired tail pipes 21, 21 having slots 28. The use of two pipes instead of one enables the designer to position the bottoms of these pipes farther from the bottom of the silencer than would be possible were but one tail pipe used. The use of an elliptical tail pipe for the same purpose will be discussed in connection with another embodiment of the invention. The inward ends of the tail pipes 2? are close together in substantially the geometrical center of the chamber l5 and close under the inlet conduit It, which .is hot at this point. It will be seen that the exhaust gases pass in contact with the outside plate 24. All the additional water is here separated out and passes out of the chamber l5 through the drain 25 The conduits 23 may be rendered anti-resonant by the apertures 26 after the manner disclosed in my United States Patent No. 2,265,342. The apertures in this case are..

located on the top side of the conduit, as a preof the inlet pipe and consequently have their temperatures raised a certain amount. I have found that this raising of the exhaust gas temperature is effective in preventing plume formation when the exhaust encounters cold air. Ordinarily, a rise of thirty degrees Fahrenheit will make the exhaust invisible under most conditions of ambient temperature and humidity.

' Means for improving the heat-transfer to the dried exhaust gases will be disclosed in connection with other embodiments of the invention.

Figs. 5, 6, and 7 show a simple type of water separating silencer comprising a generally cylindrical casing 29 having end headers 30 and 3| and an intermediate header 32 which divides the casing into two chambers 33 and 34 of unequal size. An inlet conduit 35, provided with an antiresonance slot 31 and a water inlet connection 36, passes through the end header 30, turns downwardly, and opens within the adjacent chamber 33. Slot 3? is preferably located in the bottom of the conduit. The two chambers are connected by a pair of conduits 33, having anti-resonance apertures 39, and extending from the upper portion of chamber 33 downwardly through partition 32 into outlet chamber 34. Anti-splash plates 40, M, set at an angle with the bottom of the silencer prevent splashing of the entrained waterand permit the separated water to drain out through the drains 62, 43, respectively. The relatively dry exhaust gases pass to atmosphere through the tail pipe assembly 44 opening to the upper part of chamber 34 and having an antiresonance slot-like aperture 45 preferably extending part-way only to header 3!.

It is a principle of my invention that the waterbearing exhaust gases should enter at a point near the top of a chamber and be directed downwardly so as to assist gravity in the separation of the water. Outlet connections from the chamber should be as high up as possible in this type of distinctly at a disadvantage when any considerable amount of water is present, especially in the cases of horizontally disposed devices such as are herein described. I have shown a simple means of introducing water into the exhaust gases as they enter the silencer, but the invention is by no means limited to such simple means. I may use a series of nozzles, apertures, or a circumferential slot, so long as the mixing of water and exhaust gas takes place largely in the inlet conduit.

For more effectively reheating the exhaust gases in the outlet chamber, I may use extended heating surfaces in the form of fins, such as are shown in Figs. 9 and 10. The device there shown is similar to that shown in Fig. 1 but having that portion of the inlet conduit 46 which passes through the outlet chamber equipped with fins 41 and th twin tail pipe assemblies 48 fitted with fins 49. This arrangement greatly improves the transfer of heat from the 'hot gases in the conduit 46 to the gases in the tail pipes 48.

Another method of improving the re-heating is to discharge a portion of the hot gases entering the silencer directly into the outlet chamber of the silencer. Fig. 11 shows a modification of the invention wherein some of the hot exhaust gas in the conduit 50 is led through a small, internally disposed silencer 5|, which may itself be of the spark arrester type, into the outlet chamber 52, thence to atmosphere through the tail pipe 53, which preferably is of elliptical crosssection 'in order to keep its lower surface as high as possible. In this particular embodiment, any sparks passing through th auxiliary silencer 5| will impinge upon the wet bottom interior of the chamber 52 and be quenched. By directing the outlet of the auxiliary silencer at the drain sparks can also be quenched.

An improvement of this method of reheating the exhaust gases is shown in Fig. 12, wherein a small externally disposed dry spark arrester silencer 54 by-passes some of the exhaust gas from the inlet conduit 55 directly into the tail pipe 56. In this embodiment of the invention, no heat is wasted in heating the shell of the silencer nor the separated water therein. The external silencer 54 is preferably lagged to preserve the heat of the gas. A valve 51 may be used to control the amount of gas passing through the external silencer.

Another means for reheating the exhaust gases is to make use of an electrical heat exchanger of any desired type positioned in the tail pipe leading from a silencer wherein the admixed water has been separated out. Figs, 13, 14 show diagrammatically such a construction wherein electrical heating grids 58, 59 are inserted in the tail pipe 60 leading from a water separating silencer 6 I.

When fresh exhaust gas is to be used to reheat the gas cooled by the introduction of water into the gas stream, it will be seen that it is advantageous to employ a construction wherein the inlet and outlet pipes of the silencer are in proximity to each other. In the case of electrical or other external reheating means, these can be applied to the tail pipe of any exhaust silencer.

Fig. shows a modification of the device of Fig. 1 wherein the inlet conduit 82 is surrounded by the return passageway 63 formed between the exterior of the conduit 62 and the interior of an eccentrically disposed member 64. An end view of this device is shown in Fig. 16. Anti-resonance holes 65 are put in the side of the member 64 as shown. This arrangement affords goodcontact between the top portion of the conduit 82 and the cooled returning gases in the crescent shaped passage 63. To further increase the heat transfer, extended heating surfaces 66, preferably formed of perforated metal, may be positioned between the members 62 and 64, substantially as shown.

Heretofore in this specification the drain pipes have been simply mentioned with no discussion as to their design. It has been observed that a simple drain pipe leading to atmosphere or discharging into a shallow tank may not behave in at a point spaced from a wall thereof, means a regular and uniform manner, but may cycle. By this is meant a periodic train of events which may include partially filling up the chamber to which the drain pipe is connected, and a subsequent rapid expulsion of the water followed by a discharge of gas co-mingled with water through the drain pipe. Either of these extreme conditions is to be avoided. The presence of large amounts of water in the silencer cuts down the effective volume of the chambers and causes an unnecessary accumulation of mass which particularly on board ship, is undesirable. Discharging of gas through the drain is equally undesir'able.

One simple method of overcoming this difnculty is to provide a deep tank for the water to discharge into against a head of water substantially greater than the gas pressure within the chamber with which the drain is associated. Such a device is shown in Fig. 17, wherein the silencer 81 drains into the drain pipe 68 which extends to a point near the bottom of the concentrically disposed tank or trap 69 having an opening and secondary drain 10 positioned at the top, as shown.

Fig. 18 shows another type of successful anticycling drain which makes use of the principle of venting the drain. It comprises the opening H in the bottom of the chamber 12, the short snout l3 surrounded by the concentrically disposed box 14 fitted with the vents I5 and having an opening 16 positioned immediately below the snout l3 and communicating with the drain pipe proper 11. One or more small holes, say of diameter, may be used; no substantial amount of gas escaping since the outlet issubstantially completely flooded with water.

Venting may also be accomplished by permitting the introduction of small amounts or exhaust'gas from the chamber into the drain. It has been found that if the water leaving the chamber through the drain is given a whirling motion, a certain amount of exhaust gas will be entrained with the water and will effectively prevent cycling. Fig. 19 shows a silencer chamber 18 together with a drain box '19 and drain 80, discharging into a collecting tank 8i. In the drain box 19 are positioned whirler vanes 82. A plan view of this arrangement is shown in Fig. 20.

It is a feature of these devices which have more than one chamber each equipped with a drain, that the drains are preferably run separately to their own tanks and are not coupled together with any manifolding arrangement at or near the silencer. Such manifolding generally results in blowing some of the water from the first chamber into the second chamber, a circumstance which precludes the possibility of successful operation.

What I claim is:

l. A water-cooled silencer comprising a generally horizontal casing, a partition dividing the casing into a pair of chambers, an inlet conduit having its end opening into one of the chambers for introducing water into the inlet conduit, a screen spaced from said wall between it and the open end of said conduit, one or more conduits extending through-the partition and connecting the 'two chambers, an outlet conduit opening into the second chamber, and means for draining water from the bottom of the casing.

2. A water-cooled silencer comprising a generally horizontal casing, a partition dividing the easing into a pair of .chambers',;,an inlet conduit having its end opening into one of the chambers at a point spaced from a wall thereof, means for introducing water into the inlet conduit, a screen spaced from said wall between it and the open end of said conduit, one or moreintermediate conduits extending through the partition and opening into each chamber, the opening into the first chamber being located near the top thereof, anoutlet conduit opening into the second chamber at a point near the top thereof, and means for draining water from the bottom of the casing.

3. A water-cooled silencer comprising a generally horizontal casing, a partition dividing the casing into a pair of chambers, an inlet conduit having its end opening into one of the chambers at a point spaced from a wall thereof, means .ior introducing water into the inlet conduit, a :screen spaced from said wall between it and the open end of said conduit, one or more intermediate conduits extending through the partition and opening into each chamber, the open- :ing into the first chamber being located near the top thereof, and the opening into the second chamber being spaced from a wallthereof, a screen spaced from said wall between it and the open end of the intermediate conduit, an outlet conduit opening into the second chamber ata point near the top thereof, and means for draining water from the bottom of each chamber.

4. A water-cooled silencer comprising a generally horizontal casing, a partition dividing the casing into a pair of chambers, an inlet conduit having its end opening into one of the chambers at a point spaced from a wall thereof, means for introducing water into the inlet conduit, a screen spaced from said wall between it and the open end of said conduit, one or more conduits extending through the partition and connecting the two chambers, an outlet conduit opening into the second chamber, means for draining water from the bottom of the casing, and means for reheating the liquid-freed exhaust gas leaving the silencer.

5. A Water separating silencer comprising a horizontal, generally cylindrical casing with outwardly dished ends, a partition dividing the casing into two chambers, an inlet conduit extending through one end header and the partition near the top of the casing and opening into the chamber remote from said header, a water inlet entering the inlet conduit at a point adjacent the partition, a screen spaced from the second header, a plurality of conduits extending through I the partition in the upper portion of the casing and opening into the two chambers, water drains in the bottoms of the first and second chambers, and one or more outlet conduits extending laterally into that chamber remote from the open.

end of the inlet pipe and spaced from the bottom thereof.

6. A water separating silencer comprising a horizontal, generally cylindrical casing with outwardly dished ends, a partition dividing the cas-.

ing the inlet conduit at a point adjacent the par--,

tition, a screen spaced from the second header, a plurality of conduits extending through the partition in the upper portion of the casing and opening into the two chambers, water drains in the bottoms of the first and second chambers,

a second screen covering the lower portion of the first chamber and the drain opening therein, and one or more outlet conduits extending later ally into that chamber remote from theopen end of the inlet pipe and spaced from the bottom of said chamber. i j

7. A water separating silencer comprising a horizontal, generally cylindrical casing with outwardly dished ends, a partition dividing the casing into two chambers, an inlet conduit extending, through one end header and the partition near the top of the casing and opening into the chamber remotefrom said header, a water inlet entering the inlet conduit at a point adjacent the partition, a screen spaced from the second header, a plurality of conduits extending through the partition in the upper portion of the casing and opening into the two chambers, water drains in the bottoms of first and second chambers, a second screen covering the lower portion of the first chamber and the drain opening therein, a third screen spaced from the first named header, and one or more outlet conduits extending lat erally into that chamber remote from the open end of the inlet pipe and spaced from the bottom of said chamber.

8. A water separating silencer comprising a horizontal, generally cylindrical casing with outwardly dished ends, a partition dividing the casing into two chambers, an inlet conduit extending through one end header and the partition near the top of the casing and opening into the chamber remote from said header, a water inlet entering the inlet conduit at a point adjacent the partition, a screen spaced from the second header, a plurality of conduits extending through the partition in the upper portion of the casing and opening into the two chambers, water drains .in the bottoms of the first and second chambers, and one or more outlet conduits extending laterally into that chamber remote from the open end of the inlet pipe and spaced from the bottom thereof, the portion of the exhaust and inlet conduits within their common chamber being provided with heat radiating fins.

9. A water separating silencer comprising a horizontal, generally cylindrical casing with out wardly dished ends, a partition dividing the easing into two chambers, an inlet conduitextending through one end header and the partition near the top of the casing and opening into the chamber remote from said header, a water inlet entering the inlet conduit at a point adjacent the partition, a screen spaced from the second header, aplurality of conduits extending through the partition in the upper portion of the casing and opening into the two chambers, water drains in the bottoms of the first and second chambers, and one or more outlet conduits extending laterally into the chamber remote from the open end of the inlet pipe and space from the bottom thereof,

- and means including an acoustically separate silencer for by-passing a fraction of hot gas from the inlet conduit into the exhaust gas stream.

10. A water separating silencer comprising a horizontal, generally cylindrical casing with outing through one end header and the partition near the top of the casing and opening into the chamber remotefrom said header, a water inlet header,a plurality of conduits extending through r the partition in the upper portion of the casing and opening into the two chambers, water drains in the bottoms of the first and second chambers, one or more outlet conduits extending laterally into that chamber remote from the open end of the inlet pipe and spaced from the bottom thereof, and means for heating the exhaust gas stream passing out of the last-named chamber.

11. A water-cooled silencer comprising a generally horizontal casing, a partition dividing the casing into a pair of chambers, an inlet conduit slanting downwardly the first chamber and having its open end directed generally in the direction of the lower corner of said chamber adjacent the partition, means for introducing water into the inlet conduit, a screen located over said corner between it and the open end of the inlet conduit, one or more intermediate conduits slanting downwardly from the upper portion of the first chamber through said partition and opening generally in the direction of the lower corner of the second chamber remote from the partition, a screen located over said corner between it and the open ends of the intermediate conduits, an outlet conduit leading from the upper portion of the second chamber, and means for draining water from the chambers.

12. A water-cooled silencer comprising a generally horizontal casing, a partition dividing the easing into a pair of chambers, an inlet conduit slanting downwardly the first chamber and having its open end directed generally in the direction of the lower corner of said chamber adjacent the partition, said inlet conduit extending substantially half way through the first chamber and being longitudinally slotted in its bottom portion, means for introducing water into the inlet conduit, a screen located over said corner between it and the open end of the inlet conduit, one or more intermediate conduits slanting downwardly from the upper portion of the first chamber through said partition and opening generally in the direction of the lower corner of the second chamber remote from the partition, a screen located over said corner between it and the open ends of the intermediate conduits, an outlet conduit leading from the upper portion of the second chamber, said outlet conduit opening into the second chamber substantially midway of its length and having a slot formed in a portion of its surface remote from the bottom and extending partway only from its open end to the end of the casing. and means for draining water from the chambers.

13. A silencing apparatus for exhaust gas including means for dividing the exhaust gas into major and minor portions, means for mixing water with said major portion. means for separating water from said major portion, a separate dry silencer for the minor portion, and means for commingling the silenced minor portion with the water-freed major portion.

14. A water-separating silencer or the like including a casing having a screen spaced from a wall thereof, a duct for directing gas and entrained water against the screen, and a drain conduit leading downwardly from the bottom of the casing, said conduit having an upwardly directed portion having a height sufiicient to impose a head substantially greater than the gas pressure in the casing.

15. A water separating silencer or the like including a casing having a screen spaced from a wall thereof, a duct for directing gas and entrained water against the screen, a drain conduit leading downwardly from the bottom of the easwall thereof, a duct for directing gas and entrained water .against the screen, and a drain conduit leadingdownwardly from the bottom of the casing, said conduithaving an enlarged cham- ..ber vented to atmosphere to prevent cycling.

18. A water separating silencer or. the like comprising a substantially horizontal chamber, a screen spaced from one end of the chamber and providing a free water and gas separating chamber between it and the end of the chamber, a duct substantially smaller than the screen and having an open end located on that side of the screen remote from said wall and in proximity to the screen so as to project gas and entrained water against the screen, a second duct for removing gas from the chamber and having an open end spaced both from the screen and from the bottom of the chamber, and a water drain leading from the bottom of the chamber.

19. A water separating silencer or the like comprising a substantially horizontal chamber, a screen spaced from one end of the chamber and providing a free water and gas separating chamber between it and the end of the chamber, a duct substantially smaller than the screen and having an open end located on that side of the screen remote from said wall and in proximity to the screen so as to project gas and entrained water against the upper part of the screen, the end wall of the chamber opposite the open end of the duct being directed downwardly away from said open end, a second duct for removing gas from the chamber and having an open end spaced both from the screen and from the bottom of the chamber, and a water drain leading from the bottom of the chamber.

20. A water separating silencer or the like comprising a substantially horizontal chamber, a screen spaced from one end of the chamber and providing a free water and gas separating chamber between it and the end of the chamber, a duct substantially smaller than the screen and having an open end located on that side or the screen remote from said wall and in proximity to the screen so as to project gas and entrained water against the upper part of the screen, the end wall of the chamber opposite the open end of the duct being directed downwardly away from said open end, said screen being spaced from the end wall substantially one-fifth the diameter of the duct and the duct having its open end located substantially one and a half times its diameter from the end wall a second duct for removing gas from the chamber and having an open end spaced both from the screen and from the bottom of the chamber, and a water drain leading from the bottom of the chamber,

21. A silencing apparatus for exhaust gas including a conduit for dry hot exhaust gas, means for dispersing water in the stream of exhaust gas to cool it, means for separating water from the cooled exhaust gas, and means for directing the water-freed exhaust gas into heat exchange gas.

22. A silencing apparatus for exhaust gas including a conduit for the exhaust gas, means for dispersing water in the stream of exhaust gas within said conduit, means for separating water from the exhaust gas, and means for directing the water-freed gas into heat exchange relation to a portion of said conduit containing hot exhaust gas unmixed with water.

23. ,A silencing apparatus for exhaust gas including a chamber, a hot exhaust gas conduit passing through the chamber, means for mixing water with the hot gas, means for separating the water from the hot gas, and means for conducting water-freed gas from the chamber in heat exchange relation to a portion of said conduit containing hot exhaust gas unmixed with water,

said conduit and conductingmeans being provided with heat conducting fins.

24. A silencing apparatus for exhaust gas comprising a water separating chamber, an exhaust gas reheating chamber, a hot exhaust gas conduit passing through the reheating chamber and thrcuigh a major portion of the separating chamber, a water inlet located within the separating chamber for dispersing water in the gas within the conduit, one or more screens within the separating chamber for separating water from the gas, and conduits for conducting water-freed gas from the separating chamber to the reheating chamber to receive heat from the hot exhaust conduit and for conducting the reheated gas out of the reheating chamber. I

ROLAND B. BOURNE REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 661,276 Reenstierna May 6, 1900 887,988 Wakley et a1 May 18, 1908 1,938,849 Maxim et a1. Dec. 12, 1933 1,992,586 Tobin Feb. 26, 1935 2,455,965 Wohlberg Dec. 14, 1948

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