US2556107A

US2556107A - Liquid heating system

Info

Publication number: US2556107A
Application number: US8849A
Authority: US
Inventors: Roswell Charles Neil
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-02-17
Filing date: 1948-02-17
Publication date: 1951-06-05
Anticipated expiration: 1968-06-05

Description

June s, 1,951 C. N. RQSWELL 2,556,107

LIQUID HEATING SYSTEM f Filed Feb, 17, 194s 2 sheets-sheet 1 Patented June 5, 1951 UNITED STATES PATENT OFFICE 11 Claims.

This invention relates to an improved heat exchanger and controls therefor for heating flowing liquids to any desired temperature and automatically maintaining the temperature of the heated liquid substantially constant.

In my copending application, Serial No. 737,676, iiled March 2'?, 1947, now Patent o. 2,533,141, I have disclosed and claimed a liquid heating system wherein means are provided for auto-4 matically controlling the flow of liquid being heated, for automatically maintaining the temperature of the liquid substantially constant and for removing the condensate from the heater at a controlled rate. Systems of this type are partic'la'rly useful for heating food products such as milk, fruit juices, and the like where very close control must be maintained, but it is believed obvious that any liquid may be heated in such a system. The present heat exchanger is an improvement over that disclosed in the copending application in that the condensate removal means is now a compact unit occupying a minimum of space and is arranged to operate in a more simple manner. In the present invention the heating chamber is provided with removable headers and each header is sealed by means of an inexpensive disposable paper gasket,

The primary object of the present invention is to provide a liquid heating system employing steam as the heating medium in conjunction with. means vfor removing condensate including a condensate chamber communicating directly with a steam chamber, a pump having its intake communicating with the condensate charnber., an outlet from the pump, and means for recirculating a portion of the condensate from the outlet conduit through said pump.

A further object of the invention is to provide such a liquid heating system wherein the outlet from the pump communicates with a Venturi ejector having a gas line extend-ing between the ejector and the condensate chamber for removing non-condensible gases, and means for preventing escape of condensate from the system when the gases are vented.

Another object of the invention is to provide means for ejecting condensate to the sewer or the like comprising a valve in an outlet line from the pump with this valve being operated by a float in the condensate chamber so that a relatively constant level is maintained in the condensate chamber and thus a relatively constant head is maintained on the pump.

A still further object of the invention is to provide such a condensate ejecting system wherein the float operated valve is located in the condensate chamber with fluid-tight passages being provided to and from the valve for permitting access thereto.

Another object of the invention is to provide such a system wherein the Venturi ejector that is used for the removal of non-condensible gases is maintained submerged in a substantially constant head of condensate in order that the ejector will operate with high efficiency.

A still further object of the invention is the provision of a steam chamber or the like having a removable header thereon and a disposable gasket of paper serving to seal the header' on the chamber.

Other objects and advantages of the invention will become apparent in the following description of one embodiment of the same taken in conjunction with the accompanying drawings. Of the drawings:

Fig. 1 is an elevation of one embodiment of the invention with a portion broken away for clarity of illustration; Fig. 2 is an enlarged sectional elevation of the apparatus of Fig. 1 illustrating the means for withdrawing steam condensate and non-condensible gases; and Fig. 3 is an enlarged fragmentary elevation of a portion of a header, gasket and the adjacent portion of the steam chamber.

In the embodiment shown in the dra-wings, there is provided a heat exchanger Ill formed with an expansion ring Illa near one end thereof, a centrifugal pump II for pumping liquids through the exchanger, a steam supplyrline I2 to the exchanger, a steam supply valve I4 in the steam line I2 for regulating the amount of steam, a thermostatically operated temperature control pilot valve I5 for controlling the operation of the valve I4 from the temperature of the heated liquid, a steam condensate chamber I6 located below the heat exchanger I0 and communicating therewith, a second centrifugal pump I1 for drawing condensate from the condensate chamber I6, a oat operated valve I8 through which the pump I1 exhausts condensate, a Venturi ejector I9 through which condensate is forced by the vpump I1, and a housing 20 around the Venturi ejector IB adapted to contain condensate at a substantially constant level and pressure.

The heat exchanger I0 is provided with a plurality of substantially parallel pipes 2| extendi ing from end to end thereof and a pair of

headers

22 and 23 at the ends of the heat exchanger partitioned so that the liquid being heated may ilow back and forth through the pipes. The interior of the heat exchanger is provided with a baille 60 above the pipes 2|. This baille is provided with spaced openings 6ta therein and is used to distribute the steam evenly throughout the length of the heat exchanger.

Liquid to be heated is conveyed through a pipe 24 into the intake of the first centrifugal pump I I. The outlet of the pump communicates through a pipe 25 to the inlet cf the heat exchanger Ill.V The outlet of the heat exchanger is connected by a pipe 26 to a cross-pipe 2 having four branches. The pipe 26 communicates with one branch of the cross-pipe while a second branch serves as .a product outlet through a hand operated valve 28. A third branch has the thermostatically operated temperature conv of steam that is admitted through the steam supply line I2 to the heat exchanger IFJ. As was described in the above-mentioned copending application Serial No. 737,676, now Patent No. 2,533,141, the pilot valve i is used as a temperature controller and is provided with a thermostat bulb extending into the cross-pipe 2l so that it is in contact with the heated liquid flowing from the heat exchanger. When the heated liquid reaches a temperature greater than a predetermined temperat-ure, a relief port in the pilot valve VI5 is opened and the air supply from line 8| and pressure within line 32 is vented to atmosphere,

thereby relieving pressure on the diaphragm in the valve I4 and permitting the spring I4a to close the valve. When the temperature of the heated liquid is below the predetermined temperature, the pilot valve I5 will close the vent and permit air under pressure to flow through the line 3 2 and act on the diaphragm to open valve I4. When this is done, the spring I4a on the supply valve I4 is compressed. This arrangement is described and claimed in my aforementioned copending application.

The Vadjustable spring pressure relief valve 29 is used to permit any desired amount of recirculation `of th-e liquid and is controlled by the spring tension and the amount that valve 29 is opened. The spring pressure can be varied to provide any desired pressure on the product flowing through the valve 28 and the outlet 33.

When the valve 28 is closed, however, the heated liquid will force the relief valve 29'open andV permit the liquid to flow through pipe 30 and pipe 24 into the intake of the pump II. Thus, so long as valve 28 is closed, or at least partially closedfthe liquid will be recirculated through the heat 'exchanger i6. As the temperature in the heat exchanger is controlled by the pilot valve I5, there is no danger` of the liquid becoming over` heated during this recirculation. This means for recirculating the liquid product through thej heat' exchanger is also described and claimed in my copending application, Serial No. 737,676, now

Patent No. 2,533,141,

One of 'the ilnportant features of the present invention is the improved means for removing condensate from the heat exchanger I6. This means comprises a steam condensate chamber I6 located at the bottom of the heat exchanger I0 and communicating therewith through a relatively' large opening Ib. The bottom of the con-V densate chamber is connected through a pipe 34 and a pipe 35 to the intake of a centrifugal pumpV The outlet of the pump I'I is connected through pipes 6I and 36 to a Venturi ejector I9.v This Venturi ejector is of a standard type and' is connected through a pipe 31 to the interior of forced into the gas line.

l centrifugal pump I'I. casing of the pump I'I, pipe 6I and pipe 46 is ejector.

the condensate chamber I6 at a point above the highest level of the condensate I6b in the chamber. With this arrangement the Venturi ejector I9 creates a vacuum and draws non-condensible gases through the pipe 3'I and mixes them with the condensate being forced throng-h the Venturi The ejector I9 is surrounded by a cylindrical housing 2D having its top provided with a gas outlet line 38. The Venturi ejector I9 is arranged vertically in the housing 20 and discharges against a baflie 20a located in front of the inlet on the line 38 sov that the condensate will not be The gas outlet line 38 leads to a gas escape chamber 39 having an opening 39a in the top thereof through which the gas can escape into a discharge line 40. The gas escape chamber 39 is provided with a float 4| having an upstanding stem 4Ia held in position by a guide means 42 so that it is aligned with theV opening 39a. This float and stem is provided so that if condensate should flow through the gas outlet line 38 into the chamber 36, the buoyancy of the iloat 4I would cause it to rise and close theV opening 39a and thus prevent the escape of condensate out the opening 39a. Any condensate that enters the gas line 38 is returned to the bottom of the housing 20 by means of a return line 43.

The bottom of the housing 20 is connected through a pipe 44, a spring pressure relief valve 45 and a pipe 35 to the intake of the centrifugal pump I'I. K

The condensate outlet pipe 6I from the pump I'I is connected through a pipe 46 to the float operated valve I8. The other side of the float operated valve is connected to a check valve 41 which permits flow of condensate in a direction away from the valve I8 but not towards it.

The float operated valve I8 is located in an extension I 6c of the condensate chamber I6. Access to the valve is provided by a lower pipe section 53 attached to pipe 46 and extending through the condensate chamber extension I6a. A similar pipe 54 extends through the upper part of the condensate chamber I6 and provides access to the upper part of the valve. This pipe 54 is connected to the check valve 41. Each of the pip-

es

53 and 54 is sealed by means of a packing` 55 therearound with each packing being held compressed against its pipe by means of a threaded compression collar 56. With this arrangement the condensate discharge is connned within the body of the'valve I8 and cannot enter the chamber I 6. This arrangement also permits free play of the arm on the float 48.

The valve I8 is operated by a float 48 located within the condensate chamber I6. The float 48 and valve I8 are so arranged that when the float rises the Valve is opened and when the float falls the valve is closed. With this arrangement a substantially constant level of condensate is maintained in the chamber I6 andvth'us a substantially constant head is maintained on the The pressure within the maintained constant, thereby permitting the pump to discharge condensate at a constant rate under variable temperatures and pressures within the chamber I6.

In order that condensate flowing from the heat exchanger I0 along the bottom thereof and then through the opening Iilb into the condensate chamber I6 will not cascade onto the float 48 and' affect its operation, there is provided a substantially circular vbaille 48 having. the 'shape of asedio? cascading through the opening mb will strike the baie 43 and be directed onto the walls of the condensate chamber I6 so that the condensate will not strike the float 48 except for the small amount that condenses on the pipes 2l above the barile 49 and drops directly through the open top of the baille 49 onto the oat 48. This small amount does not materially affect the operation of the float. The end of the pipe 3l which is used to convey non-condensible gases from the heat exchanger is located immediately beneath the baille 49 so that this end of the pipe is also protected by the balile.

In the operation of the condensate removal means, the float operated valve I8 will be maintained closed until the condensate I5b in the condensate chamber I6 reaches a predetermined level. While this valve is closed, condensate is withdrawn through

pipes

34 and 35 into the intake of the centrifugal pump Il. The con densate is then ejected from the pump through pipes 6I and 38 into the Venturi ejector I9. The Venturi ejector draws non-condensible gases from the heat exchanger through the pipe 3'I and ejects the mixed gases and condensate against the baliie 23a in the housing 2D. The non-condensible gases rise to the top of the housing 2G and escape through the gas outlet line 38, chamber 39, opening 39a and line 4G. The housing 2c is substantially illed with condensate at all times so that the Venturi ejector remains submerged. Any condensate owing into the gas outlet line 3E! will be returned by line 43 to the bottom of the housing 2U. Escape of this condensate through the opening 39d will be pre vented by operation of the float 4I and stem 4Ia. In normal practice, the gas escape chamber 39 will be substantially filled at all times with noncondensible gas under pressure greater than atmosphere due to the resistance of the spring pressure relief valve 45. When all gases in chamber 39 have escaped, condensate enters the chamber 33 and raises lioat 4I to close opening 39a and prevent the escape of condensate. The condensate in housing that surrounds the Venturi ejector I9 is necessarily recirculated through pipe 44 and pipe 35 back to the intake oi' the pump where it is again ejected from the pump through pipe 6I 4and pipe 36, and thus back through the ejector I9 and again into the housing 2li. This recirculation is necessary because when the float-operated valve I8 is closed, as shown in Fig. 2, no condensate can be forced out pipe 46 and no further condensate is withdrawn through pipe 34 from the condensate chamber I6. the condensate is circulated in this described closed path.

By inter-posing springeloaded relief valve at the joinder of

pipes

44 and 35, the condensate in housing 29 is always maintained at a predetermined pressure depending upon the spring setting' of valve 45, which, as is shown in the drawing, is adjustable. With the valve 45 positioned as shown, no condensate can recirculate back to the pump from the housing 28 through With this arrangement, condensatev Thus when the valve i8 is closed, as shown,

pipes

44 and 35 until the pressure of the spring.

of the valve 45 has been overcome. As in the closed system shown this recirculation is achieved, the condensate within housing 2l) is always maintained under a pressure approximately equal to the setting of the relief valve 45 as otherwise no condensate could flow fromV housing 2B through the relief valve 45 and this flow is forcibly achieved because of the above described closed system.

As the pressure of the condensate in housing 29 is maintained at a predetermined superatmospheric pressure because of the loading of the spring in the relief valve fili, the non-condensible gases in the gas escape chamber are also maintained at this super-atmospheric pressure as the gases flow out the opening 38a. rThis opening being restricted, as shown in the I drawings, causes a. relatively slow iiow of the be sufficient to force a portion of the condensate from housing 2l! through pipe 5@ into the steam supply line 2I to desuperheat the steam.

When the level of condensate in the condensate chamber I6 becomes greater than the predetermined level, the float "58 rises and opens the float operated valve I8. When this valve is opened, condensate is forced by the pump i'l through the pipes BI and 45, float operated valve itv and kcheck valve 4l into a sewer or condensate sys tern at full pump pressure. This causes the level of condensate in the chamber it to fall and thus lowers the float 48 until the valve i5 is again closed. During this cycle of operation, a portion of the condensate is being recirculat-ed through the pump I1 while another portion is used to cie-superheat the steam supply as has been previously described.

In one embodiment of the invention, low pressure steam is used for heating the heat exchanger. This steam, in one embodiment, is irom 5.5 to 30 pounds absolute pressure, although it is obvious that other pressures may be used. With steam supplied within the range ci' 5.5 to 3G pounds per square inch absolute, the liquid to be heated may easily be maintained at a temperature between 9G and 229c F. without reduit ing the liquid to remain for too great a time in the heater. The product may be heated to any desired temperature, however, by merely adjusting the thermostatically operated pilot valve l5. When it is desired to heat the product to a higher temperature, it will be advisable to employ at correspondingly higher pressures. The range of 5.5 to 30 pounds steam pressure is desirable when heating sensitive liquids such as milk, fruit juices and the like. Within this range, it is easier to prevent scorching, precipitating the solids, destruction of food value and the like.

In some embodiments of the invention, the condensate within the housing 2i) is maintained at from 5 to 12 pounds per square inch pressure by the action of the relief valve 45. This pressure serves to force the noncorni-ensible` gases through the opening 33d and to force a lsist the internal pressures.

portion of the condensate through the line 50 into the steam supply line I2 and de-superheat the steam. It is preferred that the condensate pressure in the housing 20 be kept as low as possible as the eiciency of the Venturi ejector is inversely proportional to the pressure of the condensate in which the ejector is submerged.

When the heat exchanger is first placed in operation, the steam pressures and temperatures arehigher than normal while the apparatus is reaching equilibrium. For this reason, the condensate that accumulates in the condensate chamber IB is at a higher temperature than is normally encountered. As the system reaches equilibrium and the temperature within the heat exchanger becomes lower, the accumulated'con-v densate releases some of its heat in vapor form so that it can be used in heating the liquid product. Because of the relatively large size of the opening lilb, this vapor can return to the heat exchanger without interfering with the ow of the condensate into the condensate chamber I6 from the heat exchanger. There is alsoa secondary source of vapor from the condensate chamber I6 due to the mechanical energy tran.,- rnitted to the condensate by the recirculationof a portion of the condensate. This mechanical energy is therefore also used to supply additional heat to the heat exchanger.

The vheat exchanger shown in the accompanying drawings employs an improved type of gasket for sealing each of the

headers

22 and 23 in place. As shown in Fig. 3, the header 22 is provided with a flange 22a provided on the inner surface thereof and adapted to have a metal-tometal contact with the end lilo of the heat exchanger I. The header is also provided with a partition 22h also having a metal-to-metal contact with the end Hic of the heat exchanger so as to direct the flow of liquid through the proper tubes. The header is provided with spaced bolts 5l arranged an appreciable distance from the flange 22a. Between these bolts 5| and flange 22a there is located a paper gasket 52 having its inner periphery bearing against the ange 22a and its outer periphery bearing against the bolts 5I. This paper gasket serves to seal the header and is disposable so that it may be thrown away and replaced by a new one whenever a header is removed for cleaning the heat exchanger, making repairs or the like.` The gasket prevents leakage between the flange 22a and the end member or header sheet Hic. erably made from sterile, sanitary milk cap paper stock or paper of similar quality and preferably has a width not less than about fifteen times its thickness. In a typical embodiment, it was 0.635 inch thick. The gasket is not perforated as'the outer periphery thereof merely bears against the bolts ,5L If desired, however, it may bear against a ring structure or the like. As the gasket is unperforated, it has considerable strength to re- It is preferred that the gasket be somewhat thicker than the length of the flange 22a so that when the bolts 5i are tightened, the gasket will be compressed. In the embodiment where the gasket was 0 .035 inch thick, it was compressed to a thickness of 0.028 inch when in use. The use of this improved gasket eliminates thefhazards due to blowing of regular conventional rubber and rubber base gaskets, avoids, gasket flow due to high temperatures and pressures, reduces the cost of the gaskets, permits assembly of the headers and gaskets easily and laccurately and are sanitary. No

This gasket is pref-A gasket is needed under the partition 22h as the pressures on opposite sidesof this partition 22h are substantially equal. The contacting surfaces of the flange 22a and partition 22h and the header plate lDc should be carefully machined so that an eicient metal-to-metal contact is provided.

The other header 23 is similarly provided with a flange 23a, partitions 23h and gasket 52.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, for some modifications will be obvious to those skilled in the art.

I claim:

1. In a heating system for liquids wherein the liquid is heated by passing it through a steam chamber, means for removing condensate from said steam chamber comprising a condensate chamber communicating with the steam chamber, a centrifugal pump having its intake communicating with the condensate chamber, an outlet conduit from said pump, a Venturi ejector communicating with said outlet conduit, a casing surrounding the Venturi ejector, a gas outlet line in the top thereof, a conduit extending from the Venturi ejector to the condensate chamber at a point above the normal condensate level therein for the removal of non-condensible gases, valve means in said gas outlet line for preventing the escape of condensate therethrough, and means for maintaining a predetermined amount of condensate in said casing.

2. The heating System of claim 1 wherein said Venturi ejector discharges upwardly and a balile is provided between the outlet end of the ejector and said gas outlet line for preventing the direct discharge of condensate into said outlet line.

3. YThe heating system of claim 1 wherein there is provided a conduit extending between the gas outlet line and the bottom of said casing for returning condensate entrapped in gas flowing through said line.

4. The heating system of claim 1 wherein said gas outlet line and valve means comprises a gas chamberv having an opening in the top thereof and a float operated valve in the gas chamber arranged to close said opening when condensate lls said gas chamber, and there is provided a conduit extending between the gas chamber and the bottom of said casing for returning condensate entrapped in gas owing through said eas chamber.

`5. The heating system of claim 1 wherein said means for maintaining condensate in said casing comprises a condensate conduit extending from said casing to the inlet of said centrifugal pump and a relief valve in said conduit arranged to open at a predetermined pressure.

6. In a heating system for liquids wherein the liquid is heated by passing it through a steam chamber, means for removing condensate from said steam chamber comprising a condensateY chamber communicating with the steam chamber, a centrifugal pump having its intake communicating with the condensate chamber, an

outlet conduit from-said pump, a Venturiejector communicating with said outlet conduit and discharging upwardly, a casing surrounding the Venturi ejector, a gas outlet line in the top thereof, a baffle between the outlet end of the ejector Y and said gas outlet line for preventing the direct discharge of condensate into said outlet line, a conduit extending from the Venturi ejector to the condensate chamber at a point above the normal condensate level therein for the removal of non-condensible gases, a gas chamber having an opening in the top thereof and a float operated valve in the gas chamber arranged to close said opening when condensate lls said gas chamber, a conduit extending between the gas chamber and the bottom of said casing for returning condensate entrapped in gas flowing through said gas chamber, and means for maintaining condensate in said casing comprising a condensate conduit extending from said casing to the inlet of said centrifugal pump and a relief valve in said conduit arranged to open at a predetermined pressure.

7. The heating system of claim 6 wherein there is provided a condensate line extending from said condensate conduit on the portion thereof between the casing and the pressure relief valve to the steam inlet of said steam chamber for desuperheating the steam.

8. In a heating system for liquids wherein the liquid is heated by passing it through a steam chamber, means for removing condensate from said steam chamber comprising a condensate chamber communicating with the steam chamber for collecting condensate, a centrifugal pump having its intake communicating with the condensate chamber, an outlet conduit from said pump, a valve in said conduit, a float in the condensate chamber operatively connected to the valve to open the valve when the fioat rises and close the valve when the float falls, a second outlet conduit communicating with the outlet from said pump, a Venturi ejector on said second outlet conduit through which condensate is forced by said pump, a gas conduit extending from the Venturi ejector to the condensate chamber at a point above the normal condensate level therein for the removal of non-condensible gases, said gases being entrapped in the condensate flowing through the Venturi ejector, a casing into which the Venturi ejector ejects condensate, and means for returning at least a portion of the condensate from the Venturi ejector to the intake of the centrifugal pump to provide for recirculation of condensate through the pump, Venturi ejector, casing, and back to the pump.

9. In a heating system for liquids wherein the liquid is heated by passing it through a steam chamber, means for removing condensate from said steam chamber comprising a condensate chamber communicating with the steam chamber for collecting condensate, a centrifugal pump having its intake communicating with the condensate chamber, an outlet conduit from said pump, a Valve in said conduit, afloat inthe condensate chamber operatively connected to the valve to open the valve when the iioat rises and close the valve when the float falls, a second outlet conduit communicating with the outlet from said pump, a Venturi ejector on said second outlet conduit through which condensate is forced by said pump, a gas conduit extending from the Venturi ejector to the condensate chamber at a point above the normal condensate level therein for the removal of non-condensible gases, said gases being entrapped in the condensate flowing through the Venturi ejector, a casing surrounding the Venturi ejector, a gas outlet line in the top thereof, a conduit extending from the Venturi ejector to the condensate chamber at a point above the normal condenate level therein for the removal of non-condensible gases, valve means in said gas outlet line for preventing the escape of condensate therethrough, and means for main- 10 taining a predetermined amount of condensate in said casing.

10. In a heating system for liquids wherein the liquid is heated by passing it through a steam chamber, means for removing condensate from said steam chamber comprising a condensate chamber communicating with the steam chamber for collecting condensate, a centrifugal pump having its intake communicating with the condensate chamber, an outlet conduit from said pump, a valve in said conduit, a float in the condensate chamber operatively connected to the valve to open the valve when the float rises and close the valve when the iioat falls, a second outlet conduit communicating with the outlet from said pump, a Venturi ejector communicating with said outlet conduit and discharging upwardly, a casing surrounding the Venturi ejector, a gas outlet line in the top thereof, a baffle between the outlet end of the ejector and said gas outlet line for preventing the direct discharge of condensate into said outlet line, a conduit extending from the Venturi ejector to the condensate chamber at a point above the normal condensate level therein for the removal of non-condensible gases, a gas chamber having an opening in the top thereof` and a float operated valve in the gas chamber arranged to close said opening when condensate lls said gas chamber, a conduit extending between the gas chamber and the bottom of said casing for returning condensate entrapped in gas fiowing through said gas chamber, and means for maintaining condensate in said casing comprising a condensate conduit extending from said casing to the inlet of said centrifugal pump and a relief valve in said conduit arranged to open at a predetermined pressure.

1l. In a heating system for liquid wherein the liquid is heated by passing it through a steam chamber, means for removing condensate from said steam chamber comprising a condensate chamber communicating with the steam chamber for collecting condensate, a centrifugal pump having its intake communicating with the condensate chamber, an outlet conduit from said pump, means for recirculating at least a portion of the condensate from the outlet conduit through said pump, a Venturi ejector also in said recirculating system communicating with the outlet of said pump, means for maintaining said ejector normally submerged in a portion of the con-V densate, means for forcing another portion of the condensate through said ejector for creating a vacuum therein, and gas conduit means extending between the vacuum creating portion of said ejector and the steam chamber for removing noncondensible gases therefrom.

CHARLES NEIL ROSWELL.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,252,593 Lovekin Jan. 18, 1918 1,312,512 Baumann Aug. 12, 1919 1,543,911 Fothergill et al. June 3,0, 1925 1,599,334 Lang Sept. 7, 1926 1,629,028 Fothergill May 17, 1927 1,793,119 Moore Feb. 17, 1931 1,845,622 Peter Feb. 16, 1932 2,181,602 Keeran Nov. 28, 1939 2,191,179 ODonnell Feb. 2.0, 1940 2,216,939 Dodge Oct. iB, 1940