US2358006A - Fluid exhauster - Google Patents

Description

Sept. 12, 1944. HARTZELL 2,358,006

FLUID EXHAUSTER Filed NOV. 5, 1941 Y v5 Sheets-Sheet l INVENTOR A T OENEY.

p ,1944. E. F. HARTZELL FLUID EXHAUSTER k s sheets-sheet 2 Filed Nov. 5, 1941 INVENT OR.

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Sept, 12, 19.44;

E. F. HARTZELL Filed Nov. 5, .1941

3 Sheets-Sheet 3 INVENTOR.

Q A TTORNEY.

FLUID EXHAUSTER Patented Sept. 12, 1944 UNITED STATESTPATENTV OFFICE FLUID EXHAUSTER Earl F. Hartzell, Milwaukee, Wis.

Application November 5, 1941, Serial No. 417,924

7 Claims.

This invention relates to improvements in fluid exhausters, and more particularly to a heating device embodying an exhauster for preventing draft deficiency in the stack and for maintaining proper draft and air supply under all operating conditions.

In steam boiler operation, the aim of the alert engineer or operator is the utilization of the maximum amount of the generated heat with a minimum of heat loss through the stack, while maintaining a uniform and constant heat delivery. In burning fuels having a high hydrogen content, and in humid climates or where a high percentage of wate vapor is in the air, a large portion of the flue gas is composed of water vapor, since in the combustion process, hydrogen unites with oxygen forming H2O. Assuming that combustion is complete, the heat loss in the stack presents the only possibility of increasing boiler efficiency. i

It has heretofore been attempted to minimize heat losses by reducing stack temperature, but in these prior attempts undesirable results have been obtained. The condensation of water vapor in the flue gases so reduced the volume of said flue gases as to affect the draft; and, further, the lowering of the temperature of the flue gases caused a reduction in volume of the flue gases entering the stack, also materially affecting the draft and creating an unstable and variable primary air supply to the boiler. Correction of these deficient draft conditions has heretofore required the use of mechanical equipment such as fans and blowers, and in the case of av power plant installation the use of costly electrical controls and indicating devices. The reason expensive equipment is necessary in the latter case is that because of the large fuel consumption and high burning rate the draftmust be precisely controlled under all operating conditions to prevent inefficiency and excessive operating costs.

When such electrically controlled mechanical draft regulating equipment is utilized there is maintenance and repair work required, and if there is a failure in the equipment interruptions of the operations of the power plant necessarily result. In addition, there is an undesirable time lag in the operation of mechanical and electrical control equipment, adding to the operating costs.

In my application Serial No. 398,087, filed June gas flow into the chimney and would normally result in a deficient draft except for the fact that means, adequate for handling the requirements of the usual domestic heating plant, is utilized for insuring movement of the flue gases out of the stack. However, when the invention of my prior application is applied to a power plant installation, with the precise requirements for draft control, a special problem is presented if it is desired to eliminate the use of the conventional electrically controlled mechanical draft equipment referred to above.

It is, therefore, an object of the present invention to provide means applicable to the construction disclosed in my prior application and also for more general use with or without an air preheater, whereby a gas volume in the stack equal to the original volume leaving the boiler is maintained without electrically controlled mechanical equipment and even though the system is so operated that the stack temperature is at a minimum. i

A more specific object of the invention is to 7 provide a construction for the purpose described which operates physically and thermally in perfect accord with the original required draft, with the positive combustion air supply to the boiler balanced against outgoing gas movement. Thus the precise control, at all points in a variable range of operating conditions, which precise control is so necessary in power plant installations, may be obtained without using costly and troublesome electrically controlled mechanical equipment and Without using any moving parts.

A more specific object of the invention is to provide a construction wherein a portion only of the flue gases leaving the boiler, which portion is not subjected to the heat reducing effects of a heat exchanger or fresh air supply as is the major portion of the flue gases leaving the boiler, is led into a Venturi shaped exhauster conduit opening into the stack; this exhauster is in communication with the outside air and the latter enters the exhauster automatically according to physical laws to be heated by the admitted flue gases.

Thus this fresh air expands and is discharged 14, 1941, a heating device is disclosed wherein Very low. This naturally changes the volumetric into the stack to combine with the other flue gases in the stack to create a total volume equal to the original volume of gases leaving the boiler plus an excess to cause movement of the gases. A perfect balance is thereby obtained at all times so that there is proper draft even though the majority of the flue gases leaving the boiler are at a relatively low temperature or are subjected through the openings in the brackets 36v and 31 r to the cooling effect of a heat exchanger or like equipment. A further object of the invention is to provide 7 a construction as above described which, when employed in conjunction with a unit of my beforementioned prior application, shunts into the exhauster conduit under pressure some of the at a desired rate of any fluid through a conduit.

' With the above and other objects in view, the

invention consists of the improved heating device v and all its parts and combinations as set forth in theclaims, and all equivalents thereof.

' In the accompanying drawings illustrating one complete adaptation of the preferred form of the invention, in which the same reference numerals designate the same parts in all of the views,

Fig. 1 is a transverse vertical sectional view of theimproved heating unit taken on line II of Fig. 2; Fig; 2 is a horizontal sectional view through the improved unit looking downwardly, with some interior parts shown in full and with other interior parts broken away and shown in horizontal section;

Fig. 3 is an enlarged fragmentary horizontal sectional view taken on line 3-3 of Fig. 1;

Fig. 4 is an enlarged fragmentary vertical sectional view taken on line 44 of Fig. 2;

Fig. 5 is an elevational view at the outlet 0 the unit showing the casting portions forming the supplementary air supply, draft control, and draft stabilizer; and g Fig. 6 is a side view of the improved unit showing it connected to a fragment of the outlet and of a boiler, with the latter illustrated in vertical section, I 7

Referring more particularly to Figs. 1 and 2 of the drawings, the device includes a cabinet I5 "having a front wall I6, a rear wall II, end walls I8, a removable bottom cover I9, and aremovable top cover 20. The walls I6, I1, and I8 are formed ofspaced members to provide aspace ZI within which air entering the" openingsZZ may travel, as indicated by the arrows in Fig. 2. A plurality of the openings 22 arranged in a vertically extending line on each side of the outlet is preferably provided. The front wall I6 is formed with a circular opening 23 communicating I with a collar 24, and the rear wall I1 is formed with a similar opening 25communicating with an outlet collar 26. The collar 24 is cooperable with a flue pipe section 2! leading from the boiler 28,

for other heating device, as shown in Fig. 6, and

the collar 26 is cooperable with a flue pipe section 29 leading to the chimney. The unit may thus be readily connected to a standard boiler '01" furnace installation by a very simple procedure.

Legs 30, having their upper ends adjustably clamped in corner fittings 3|, support the unit from the floor.

The top and bottom closures I9 and comprise spaced walls with insulating material 32 and 33 therein, and each closure has a projecting and inwardly bent flange 34 for cooperation with the edges of the side and end walls in the manner shown in Fig. 1. In addition each clo- Within the cabinet, and extending transversely across the center portion thereof, is a casting assembly 39, which is preferably formed in two half sections subsequently secured together in a leakproof manner to provide a plurality of passageways therein. One of these passageways comprises an inlet portion 40, at the inlet side of the unit, communicating with a channel 4|, with a reactive channel 42, with a Venturi chamber 43, channel 44, nozzle 45, and throat '46. The throat 46 communicates with a pipe 41 leading into the final gas passageway of the boiler, as shown in Fig. 6, and also communicates with a duct 48 leading to an air supply pipe 49; .The pipe 49 extends exteriorly of the unit around to the front of the furnace or boiler and into an air control valve housing which may communicate with the. boiler above and below the fire bed, as fully disclosed in my application Serial No. 398,087. I

Referring again to Fig. l, a second passageway is formed in the casting assembly for communie cation with air inlet openings 58 on each side. This passageway comprises a channel 59 communicating with a venturi 60, and with a channel GI leading to an annular chamber 62 which surrounds the nozzle 45.

The oppositely disposed openings 58 on each side of the channel 59 are adapted to have their effective areas varied, under certain conditions of operation, by a bell 63 which is movable as indicated by the dotted lines in Fig. 9. The bell is supported on the outer end of a stem 64, and the upper end of the stem is secured to the lower.

68 in a member 69, upon tightening of a nut I0, to wedgingly compress the collar portion 61' of the bellows against the side of the opening. 58. This. forms an effective seal for the upper end of the bellows without necessitating the use of solder or other material which might melt under excessive heat. Within the bellows there may be air, gas, or liquid, responsive to temperature changes, for causing movement of the bellows to raise orlower the bell 63. v

Atthe outlet side of the unit the casting assembly hasthe shape shown in Fig. 5 to provide an air inlet opening. 'II communicating with the atmosphere through the opening I3 in the rear Wall of the cabinet. .The side walls 15 of the, casting portions, which communicate with the opening I I, taper to a passageway which is square in cross-section, as at I6 (see Fig. 3), and the passageway 16 communicates with a venturi H, which latter communicate with an outlet duct I8 leading to the exhauster n (see Fig. 1).

The air inlet openingII also communicates with a passageway portion having converging side walls I9 (see Fig. 3). converging into a passageway which is rectangular in cross-section. The passageway 80 communicates with a venturi III, and the latter with an outlet duct 82. Part of the flue gas passing through channel 44 enters a conduit 54 having its outer end in the form of a nozzle 55, and said nozzle extends into a throat 56 and discharges into the exhauster 12 as clearly shown in Fig. 1.

Referring to Fig. 2, air enterin the chamber 2I formed in the cabinet wall through the openings 22 on one side passes in the manner indicated by the arrows into the open end 83 of a heat exchanger 84. 22 on the other side passes into the open end 85 of another heat exchanger unit 86. At the front of the unit the heat exchange units terminate short of the front wall l6 to provide chambers B1 and 88. At the bottom of the cabinet th heat exchange units terminate adjacent the upper edge of a wall 89 (see Fig. l), which extends the length of the cabinet and which serves as a baifie to prevent flue gases from traveling beneath the heat exchanger until said gases have Air entering the openings passed upwardly through the spaces 81 and 88 A and then downwardly through the spaces 90 between the heat exchanger sections, as shown in Fig. 11. The Wall 89 also serves to confine dust which may be deposited by the flue gases on the bottom of the cabinet and behind the wal1 89. This dust may be readily removed by removing the bottom closure l9.

Referring to Fig. 3, the passageway 9| within the heat exchanger 84 leads to an opening 92 in a tubular projection 93 from the casting assembly, and the tubular projection 93 communicates with one of the openings 58, shown in Fig. 1.

The interior passageway 94 of the other heat exchanger 86 communicates with an opening 95 in the tubular extension 98 on the other side of th central casting assembly, and the tubular extension 96 communicates with the other opening 58 leading to the channel 59.

The heat exchange units 84 and 86 may be manufactured in an inexpensive manner from sheet-metal in the manner clearly indicated in Figs. 2, 4, and 5.

When the top closure 20 is removed, access maybe had to a clean-out cap 91 (Fig. 1) When the latter is removed, the chambers 4|, 42, 43, and 44 are accessible for cleaning.

Operation Flue gas which leaves the boiler or furnace through the smoke pipe 21 enters the opening 23 (Fig. 1) of the improved device and into the chambers 81 and 88 in front of the heat exchangers (Fig. 2). This flue gas cannot pass directly out beneath the heat exchangers because of the longitudinally extending wall 89. The gases therefore rise in the chambers 81 and 88 to the top of the cabinet and pass down into the spaces 90 between the various lengths of the heat exchange units on each side (see Figs. 2 and 4). These gases then travel through the dust collecting receptacle H4, as indicated by the arrows in Fig. 1, and are discharged through the outlet opening 25 into the stack pipe 29 leading to the chimney. While traveling through the bottom receptacle H4, dust or other foreign matter is deposited by gravity on top of the bottom closure I9 and behind th wall 89. This dust may be removed at any time by removing the bottom closure I 9.

Returning again to the inlet end of the cabinet, part of the flue gases from the pipe 21 enter the opening 40 of the center casting assembly and pass into the channels 4| and 42 (Fig. 1). These channels are rectangular in cross-section, and due to the return bend at 42, the pressure of the gases is increased. From the channel 42 the gases enter the tapering duct of circular cross-section 43. The duct 43 produces an action in the nature of a venturi, causing an acceleration in velocity, From the channel 43 part of the gases pass through the channel 44, through the nozzle 45 and into the throat 46. There is a progressive decrease in cross-sectional area -be cause the main portion of the'nozzle 45 is of less diameter than the channel 44, and the crosssectional area is again restricted when the gases pass out of the discharge opening of the nozzle 45. When the gases pass into the throat 46 a relatively low pressure area compared to atmospheric pressure is created.

Due to the difference between the relatively low pressure in the throat 46 and the atmospheric pressure, air from the outside is caused to enter the chambers 2| in the hollow wall I! of the cabinet through the two sides of the openings 22 (see Fig. 2). This air travels in the manner indicated by the arrows and enters the heat exchangers 84 and 86 through the openings 83 and I 85, traveling the length of each of these heat exchangers and entering the center casting assem-. bly through the tubular ducts 92 and 95 and openings 58 (see Fig. 3). As the air passes through the chambers 2! in the hollow walls of the cabinet it i partially heated, and it is further heated to a substantial degree while passing through the heat exchangers 84 and 86 because the outer surfaces of the heat exchangers are being constantly wiped by the hot outgoing flue gases passing downwardly through the spaces 90. Referring again to Fig. l, the heated fresh air entering the central casting assembly through the openings 58 passes downwardly through the channel 59 into a downwardl tapering chamber 80. This chamber causes an action similar to a Venturi action to accelerate the velocity of the air. From the chamber the air passes through the channel 6| where a relatively low pressure area with respect to atmospheric presssure is created which approximates the pressure in the duct portions 44 and 45. From the channel 6| the heated air flows around the nozzle 45 in the annular chamber 62 and ultimately mixes with the flue gases in the throat 48 and chamber 46. Part of this mixture of air and flue gas is discharged by the pipe 4'! into the final portion of the flue passageways of the boiler, as 'shown in Fig. 6, into a region of the boiler having a comparatively low pressure. The remainder of the mixed air and flue gases from the chamber 46 passes through the duct 48 into the pipe 49. The latter pipe may supply the mixture of air and flue gases over and under the firepot, as set forth in my application Serial No. 398,087.

It is thus apparent that the supply of mixed air and flue gases to the boiler through the nozzle 41 and pipe 49 is physically controlled and balanced through the novel construction of the unit so that said supply of the mixture of air and flue gases is proportional to the burning rate and, of course, the higher the burning rate the more of the air mixture that is required.

In ordinary heating installations any air supplied beneath the grate or over the firepot is cold air. With the present invention, however, air supplied by the nozzle 41, and pipe 49, has been preheated in the heat exchanger and also by being mixed with flue gases. Because of the heating of the air by the admixture of flue gases therewith, the air is preheated immediately and before the boiler or heat exchanger are hot. This preheated air increases the temperature of the boiler or furnace. Furthermore, due to the fact that stack action is perfectly controlled with the present invention, the gases are in contact with the heating surfaces for a greater length of time and. due to the preheated condition of the air the gases are at a higher temperature; thus heat absorption is increased. Combustion efficiency is increased by the automatic regulation of the amount of air and the elimination of excess air supply over that required. Such excess air supply always reduces efficiency. Furthermore, due to the elimination of soot, resulting in clean heating surfaces, the absorption capacity of the furnace or boiler i increased.

Inasmuch as the temperature of the boiler will progressively increase as the temperature of the incoming air supply increases, and since with the present invention the temperature of the air supply, which is heated by the flue gases, increases progressively as the boiler temperature increases, there is need to protect the boiler or furnace against damage if it is neglected in operation. Should such excessive temperatures occur, the

bellows 65 will expand thermally, moving the bell 63 toward the dottedline position of Fig. 9 to partially close off the air openings 58. This will cut down the air supply to the boiler and maintain the burning rate below the critical point,

Inasmuch as the gases leaving the boiler through the pipe 2! are cooled in the unit by transferring heat to the air passing through the heat exchangers 84 and 86, and inasmuch as the volume of these flue gases is reduced by such cooling, and because of the complete combustion which has taken place, this naturally reduces the amount of flue gases leaving the unit through the pipe 29 leading to the chimney. In order to cause movement of these gases, a supplementary air supply is provided and air is admitted through the opening 1.3 into the chamber 15. The chamber 15 opening 13.

tapers downwardly, as shown in Fig. 5, to pro:

duce a Venturi action and accelerate the velocity. The air then passes through chamber 16 into the. tapered chamber 11 where a second Venturi action takes place, again accelerating the velocity.

In power plant installations precise draft control is required. The present invention takes care of this problem by shunting part of the hot flue gases under pressure from the channel 44, through the pipe 54 and into the special exhauster 12. The pressure difference between that existing in the pipe 54 and the atmosphere causes cold air to enter'the opening 13 and to pass through the channels l5, l6, l1, and 18, unitingin the exhauster 12 with the hot flue gases discharged by the nozzle 56. This causes the cold air admitted from the opening 13 to expand and this expanded air unites with the major portion of the flue gases which are being discharged from the chamber I 14 into the stack. Inasmuch as these latter flue gases have been cooled by the action of the heat exchangers 84 and 86 their volume is greatly reduced over their original volume as they entered the unit at from the boiler. However thebxpanded air is discharged by the exhauster 12 in an amount to compensate for the volume deficiency in the stack so that there is. a volume of gases leaving the unit slightly in excess of the volume entering the unit to cause a positive draft even though the stack gases are cold. Inasmuch as it is intended that all air for combustion be supplied to the boiler in the form of a mixture by the pipes 49 and 41, as more fully explained in my prior application, there is a positive control ofthe air from the unit and the draft is automatically made proportionately positive by the exhauster. Even if the controlled air supply through the pipes 49 and 41 is not used, the improved exhauster causes a perfect balance between the draft and the'supply of air to support combustion, no matter how said air is supplied to the heating plant. Thus there is at all times the perfect control so necessary in power plant installations, without the necessity of using elec- 'trically controlled fans, blowers or the like to create draft. 7

In addition to the draft control already described there is also a draft stabilizatiom operable'to prevent excessive draft which is also effected by the admission of airthrough the air This air passes into an inwardly and downwardly tapering chamber I9, whereits velocity is accelerated, through chamber into the tapering chamber 8|, where its velocity is again accelerated, and travels out through the dischargeduct 82 into the stack pipe 29. The

outlet of the pipe 82 extends into a relatively low' pressure area with respect to atmosphere. Any pressure differential due to wind action on the chimney affects this area first, and a sufficient air supply is automatically drawn in through the opening 14 to satisfy the stack pull, without materially affecting the effective stack area for the discharge of the flue gases. The burning rate of the furnace or boiler is thus stabilized against abnormal stack action. The series of tapered chambers I9 and 8| again provide for acceleration in velocity to prevent a throttling action which might otherwise be. caused by the difference in areas between the inlet opening 13 and the discharge opening from the duct 82. The form of draft control just described, while advantageous in the present invention, is not essen: tial as other draft controls may be utilized.

The improved unit is adapted to increasethe efiiciency of a heating plant even without the discharge of a mixture of air and flue gases through the pipe 49. In such case air is admitted in the normal manner to the firepot but more complete combustion than in the usual installation is ob-' tained because of the discharge through the nozzle 41 into the final gas passageways.

The exhauster is adapted for use in other adaptations than that illustrated, and'in adapta tions other than heating plants, and is adapted for use with and without a heat exchanger, and

various changes and modifications may be made pipe leading from a heating plant to a chimney comprising, a unit having an inlet for receiving flue gases from said heating plant and having 'a flue gas outlet, a heat exchanger in said unit, means including a channel positioned to intercept part of the flue gases admittedto theunit before said gases have been lowered in temperature by the heat exchanger, said channel including portions of progressively less cross-sectional area connected'by'a tapered portion to accelerate the velocity of said gases,an exhauster conduit having a discharge opening adjacent the flue gas outlet of the unit, means for admitting fresh air to the exhauster, means for delivering some of the hue gases from said intercepting channel to said exhauster to cause expansion of the outside air which is admitted to and discharged from the exhauster, and a conduit for leading the remaining gases from the intercepting channel to the heating plant for use in promoting combustion therein.

2. A heating device for connection in the flue pipe leading from a heating plant to a chimney comprising, a unit having an inlet for receiving flue gases from said heating plant and having a flue gas outlet, a heat exchanger in said unit, means including a channel positioned to intercept part of the flue gases admitted to the unit before said gases have been lowered in temperature by the heat exchanger, said channel including portions of progressively less cross-sectional area connected by a tapered portion to accelerate the velocity of said gases, an exhauster conduit having a discharge opening adjacent the flue gas outlet of the unit, means for admitting fresh air to the exhauster, means for delivering fresh air to said intercepting channel, means connecting with said intercepting channel in advance of said last fresh air delivering means for delivering some of the flue gases from said intercepting channel to said exhauster to cause expansion of the outside air which is admitted to and discharged from the exhauster, and a conduit for leading the remaining gases after they have been mixed with fresh air from the intercepting channel to the heating plant for use in promoting combustion therein.

3. A heating device for connection in the flue pipe leading from a heating plant to a chimney comprising, a unit having an inlet for receiving flue gases from said heating plant and having a flue gas outlet, a heat exchanger in said unit, means including a channel positioned to intercept part of the flue gases admitted to the unit before said gases have been lowered in temperature by the heat exchanger, said channel including portions of progressively less cross-sectional area connected by a tapered portion to accelerate the velocity of said gases, an exhauster conduit having a discharge opening adjacent the flue gas outlet of the unit, means for admitting fresh air to the exhauster, means for delivering fresh air to said intercepting channel, a heat exchanger in the unit through which said fresh air passes for lowering the temperature of gases of combustion passing through the unit, means connecting with said intercepting channel in advance of said last fresh air delivering means for delivering some of the flue gases from said intercepting channel to said exhauster to cause expansion of the outside air which is admitted to and discharged from the exhauster, and a conduit for leading the remaining gases after they have been mixed with fresh air from the intercepting channel to the heating plant for use in promoting combustion therein.

4. A heating device for connection in the flue pipe leading from a heating plant to a chimney comprising, an enclosure having a passageway through which used gases of combustion pass, a heat exchanger in said enclosure, an exhauster conduit having a discharge opening in communication with the chimney pipe, means for admitting outside air to said exhauster, and means for separating some of the used gases before said gases have been lowered in temperature by the heat exchanger and for admitting said separated usedlgases to said exhauster to cause expansion of the outside air admitted to the exhauster.

5. A heating device for connection in the flue pipe leading from a heating plant to a chimney comprising, an enclosure having a passageway through which used gases of combustion pass, a heat exchanger in said enclosure, an exhauster conduit having a flared discharge opening in communication with the chimney pipe, means for admitting outside air to said exhauster, and means for separating some of the used gases before said gases have been lowered in temperature by the heat exchanger and for admitting said separated used gases to said exhauster to cause expansion of the outside air admitted to the exhauster.

6. A heating device for connection in the flue pipe leading from a heating plant to a chimney comprising an enclosure having a passageway through which used gases of combustion pass, a heat exchanger in said enclosure, an exhauster having a reduced inlet throat portion and havinga discharge opening at the opposite end in communication with the chimney pipe, a nozzle positioned to discharge into said throat, means for admitting outside air to said exhauster throat around said nozzle, and means for separating some of the used gases before said gases have been lowered in temperature by the heat exchanger and for conducting said separated used gases to said nozzle.

7. A heating device for connection in the flue pipe leading from a heating plant to a chimney comprising an enclosure having a passageway through which used gases of combustion pass, a heat exchanger in said enclosure, a bell-shaped exhauster having a reduced inlet throat portion at one end and having a flared discharge opening at its opposite end in communication with the chimney pipe, a nozzle positioned to discharge into said throat, means for admitting outside air to said exhauster throat around said nozzle,

- and means for separating some of the used gases before said gases have been lowered in temperature by the heat exchanger and for conducting said separated used gases to said nozzle.

EARL F. HARTZELL.

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