US1328997A

US1328997A - Superheat-limiting device

Info

Publication number: US1328997A
Application number: US136832A
Authority: US
Inventors: David S Jacobus
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1916-12-14
Filing date: 1916-12-14
Publication date: 1920-01-27
Anticipated expiration: 1937-01-27

Description

D. S. JACOBUS.

SUPERHEAT LIMITING DEVICE.

APPLICATION FILED DEC. 14, 1916- 1,328,997, 7 Patented Jan. 27, 1920.

I0 SHEETSSHEET l- INVENTOR. W

M ATTORNEYS.

D. S. JACOBUS.

SUPERHEAT LIMITING DEVICE.

APPLICATION FILED DEC. 14. I916.

1 328 991 Patented J an. 27, 192U l0 SHEETS-SHEET 2.

1 1: INVENTOR. M J.

MA; ATTORNEYS.

Patented Jan. 27, 1920.

I0 SHEETS-SHEET 3- IN V EN TOR.

/ ATTORNEYS.

D. S. JACUBUS.

SUPERHEAT LlMlTlNG DEVICE.

APPLICATION FILED DEC. 14. 19w.

1 ,328,997,- Patented J an. 27, 1920.

10 SHEETSSHEEI 4.

A TTORNEYS.

D. S. JACOBUS.

SUPERHEAT LIMITING DEVICE.

APPLICATION FILED DEC.14,I916. 1,328,997, Patented Jan. 27,1920.

N {:2 I0 SHEETSSHEET 5.

IN V EN TOR.

// A T TORNEYS.

D. S. JACOBUS.

SUPERHEAT LIMITING DEVICE.

APPLICATION FILED DEC.14,1916. 1,328,997, Patented Jan. 27, 1920.

10 SHEETSSHEEI 6.

IN V EN TOR. MM

//ATTORNEYS.

D. S. JACOBUS. SUPERHEAT LIMITING DEVICE. APPLICATION FILED DEC. 14. 1916.

Patented Jan. 27, 1920.

IO SHEETS-SHEET Z.

M4 ATTORNEYS.

D. s. JACOBUS. SUPERHEAT LIMITING DEVICE.

APPLICATION FILED DEC. I4; I916- 1 ,328, 997 I Patented Jan. 27, 1920.

I0 SHEETS-SHEET 8.

lII

any"! -2 IIIIIIIIIIII I l INVENTOR.

BY I am A TTORNEYS.

D. S. IACUBUS.

SUPERHEAT LIMITING DEVICk.

APPLICATION man 05c. 14. 1916.

Patented Jan. 27, 1920,

10 SHEEIS-SHEEI 9.

INVENTOR.

//1/I) ATTORNEYS.

D. S. JACOBUS.

SUPERHEAT LIMITING DEVICE.

APPLICATION FILED DEC. I4. 1915.

1 328 991 Patented Jan. 27, 1920,

I0 SHEETS-SHEET I0.

I I-T ZE INVEN TOR.

HM J

BY J

//1v: A TTORNEYS.

UNITED STATES PATENT OFFICE.

DAVID S. JACOEUS, OF JERSEY CITY, NEW .IERSEY, ASSIGNOR TO THE BABCOCK & 'WILCOX COMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

SUPERHEAT-LIMITING DEVICE.

Specification of Letters Patent.

Patented Jan. 27, 1920.

To all whom it may concern:

Be it known that I, DAVID S. JAooBUs, a citizen of the United. States, residing in Jersey City, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in superheat- Limiting Devices, of which the following 1s a specification.

My invention relates to an apparatus for limiting the maximum amount of superheat in superheated steam, and will be understood by reference to the accompanying drawings in which Figure 1 is a diagrammlati'c view to illustrate the principle of operation of my invention; Fig. 1, a side view of an independently fired superheater havingthe 'superheat limiting device applied thereto; Fig. 2, a side View partly in section, of one of. the doors for admitting air'into the setting, with the lever for opening same; Fig. 3, a front view of one of the doors; Fig. 4:, a front view of Fig. 1; Fig. 5, a vertical longitudinal section through the superheater; Fig. 6, a side view of the connections for passing the steam from onev section to the other of the superheater; Fig. 7 a vertical longitudinal section, with certain parts in elevation, of a series boiler to which the device is applied; Fig. 8, is a side view, with certain parts in section," of a part of the apparatus for effecting the regulation shown on a smaller :scale in Figs. 1 and 7; Figs. 9 and 10 are enlarged views partly in section, of parts of the valve and stem of Fig. 8; Fig. 11 is a side view, partly in section, of a modified form of the apparatus for efiecting the regulation; Fig. 12 is a top'view of Fig. 11; Figs. 13, 14." and 15 are enlarged views of the operative mechanism and diaphragm of the apparatus shown in Fig. 11; Fig. 16 is a side View, mainly in section, showing a, balanced valve which may be used in connection with the apparatus, the valve being shown closed; Fig. 17 is a view similar to Fig. 16, showing the valve open; Fig. 18 is a transverse section on the plane of the line 1818 of Fig.

17 Fig. 19 is a transverse section on the plane of the :line l9'l9 of Fig. 17 Fig. 20 is a transverse section on the plane of the line 2020 of Fig. 17; Fig. 21 is a side view, mainly in section, of another form of valve which may be employed for operating the power piston; Fig. 22 shows the same valve in open position; and Fig. 23 is a side View,

the outgoing superheated steam. In the form shown this comprises a container for a volatile liquid, the temperature of such liquid, and consequently the pressure of its vapor, varying as the temperature of the surrounding superheated steam varies. This "apor pressure generated in the container is utilized to set in operation certain mechanisms to limit the temperature within the superheater setting and thus limit the degree of superheat. For the purpose of explaining the rinciple of operation of my invention, I lave shown a diagraimnatic arrangement in Fig. 1 in which the-numeral l designates a portion of the superheated steam main. Within this main is a container in the form of a coiled pipe 2 closed to the steam and containing a volatile liquid such as water, alcohol or mercury having a fixed boiling point for a given pressure. The container may have any appropriate form which will insure an effective impingement of the superheated steam and a relatively large heating surface with the proper in-- ture to which the liquid is heated by the superheated steam. The latter regulator comprises a chamber 6 having a flexible dia phragm 7 upon which dia hragm rests adisk 8. When water is use as the liquid in the coiled pipe 2 the chamber 6 is filled with water upon the surface of which oil is placed to prevent corrosion of the diaphragm 7, which is preferably of hardened steel. For a given steam temperature passing over the coil 2 there will be a given vapor pressure transmitted to the chamber 6. This pressure acting upon the under side of the diphara-gm 7 is transmitted through the following mechanism The post which bears on the disk 8 is during the time the water is being admitted To the free end of the lever 9 is attachedthe stem of a valve 11 which valve controls the flow of a fluid under pressure, preferably water, entering through pipe 12 from a source of supply. From the valve chamber the fluid under pressure is delivered through a pipe 13 to-a cylinder 14 having a piston 15, which latter is connected to a power lever 16 having its fulcrum at 16. To the end of lever 16-is attached a rod 17, the movements of which rod are utilized as hereinafter .desoribed. When the valve 11 is closed, by a reduction of the vapor pressure on diaphragm 7, the power lever 16 is restored to its normal position by a counterweight 16, the water in the cylinder being discharged through a valved pipe 18. The valve in the pipe 18 is partially open at all times and the valve is not changed in position when themechanism is in operation. The valve in the pipe 18 is so adjusted that to the cylinder 14, throughthe pipe 13, the discharge through the pipe 18 is materially less than the rate at which the water is adis limited by a stop 9 The action of the regulator above described is to cause the vapor pressure gener ated in coil 2 to act through the regulator in such manner that when the temperature of the superheated steam flowing through the main l exceeds that for which the apparatus is set, the lever 9 will be raised to thereby open valve 11 to admit Water under pressure to the working side of piston 15. When the piston 15 is moved, the power lever 16 will be moved andthereby the rod 17, to eflect a reduction in the temperature of the superheated steam as will be more fully described in connection with Figs. 1 to 7. When the temperature of the steam isreduced below that at which the apparatus is set, the valve,11 will be moved to its seat by the spring 9.

On closing the valve 11 the water discharged through the valve in the pipe 18 will allow the power piston 15 to slowly regain its original position near the top of the power cylinder 14, the lever 16 having a counterweight 16 which moves the power piston 15 to its original position. In place of the counterweight 16 the system may be otherwise counterweighed, in which case it may not be necessary to use a counterweight on the lever 16.

The advantage of allowing the water which operates the power piston 15 to escape at all times through a constricted opening isthat it provides a simple means whereby the power piston 15 may return to its original position after the mechanism has been thrown-into action,.and further, there" are special advantages in using this method as the apparatus may be operated through a very small movement of the valve 11. The method described is superior in these respects to one where the water is released from the power cylinder by means of a valve actuated by the same mechanism that actuates the valve 11, as the latter arrangement would require a much closer adjustment and would be much more liable to get out of order than the one described.

In Figs. 1 to 5 inclusive, I have shown an adaptation of my invention to. an independently fired superheater in which, when the maximum degree of superheat is reached, doors will be opened to admit atmospheric air into the setting to thereby reduce the steam temperature. The superheater illustrated is substantially the same as that described in my application Serial No. 45,399, filed August 13, 1915. As shown in Fig. 5, the steam from the boiler enters through the main 19, thence passes into the. superheater header 20, through the tubes 21 into the header'20'. From the latter the steam flows through pipe 22, which is placed outside of the setting, into the superheater header 23, through the tubes 24 to header 23 thence through pipe 25, which is outside of the setting, into the header 26, through tubes 27 to header 26; thence through pipe 28 to header 29, through tubes 30 to outlet header 29'; and thence to the steam main 1." .The gases from furnace 31 flow into the secondary combustion chamber 31 and thence successively over the banks of tubes 21, 30,27 and 24 to the damper opening 32. It will be noted that the saturated steam which is admitted to the "superheater, passes through the "bank of tubes 21 which is-acted on by'the hottest gases, thus minimizin the tendency of the hot gases to burn and istort the tubes which come nearest the fire. Also that the steam is so circulated through the remaining banks with the practical advantage of requiring a minimum expense for upkeep.

The superheater is fired by any suitable furnace, the fire in which is so regulated as to maintain the desired degree of superheat. Should, however, the superheat exceed the desired maximum, atmospheric air is admitted to the interior of the setting to reduce the temperature to a point below the maximum. In the construction shown the front wall of the setting is provided with doors 33 adapted to be opened and closed by the power lever 16 and rod 17, shown in Figs. 1 to 5 as follows I The rod 17 is attached at its upper end to a lever 34 on a rock shaft 35. To the latter are secured levers 36 which, when the shaft is rotated, engage rollers 37 mounted on the doors to open the latter to admit atmospheric air into the setting. Also attached to the shaft 35 is a lever 38 carrying a counterweight 38 set at such an angle with respect to the shaft 35 that it will be inactive in producing a force tending to open the doors when the latter are closed. In order to properly adjust the action'of the counterweight 38, a second counterweight 39 is carried by a lever 39, also secured to shaft 35. The action of the power lever 16 in completely releasing the doors, when in a closed position, is an important one as it allows the doors to rest firmly against their seats when closed, and so minimize air leakage. The doors are made to seal tightly against their frames by the use of asbestos orother packing. Any number of doors may be provided. In Fig. 4, I have shown 5 doors arranged in two rows, those on the lower level being actuated by a shaft 40 connected to shaft 35 by a'link 41 and lever 42. To open the doors the shaft 35 is given a clockwise motion causing levers 36 to engage with the rollers 37, and on further rotating the shaft 35 in the same direction, the doors will be opened until they assume the position indicated at the top of Fig. 2. \Vhen the temperature of the superheated steam falls, the counter-'

weights

38 and 39 act to raise the lever 16 to its normal position, said counterweights being so set that, together with-the unbale anced weight of the doors, there will be an upward force produced on the rod 17.

The pressure gage 43, shown in Fig. 1, is acted on by the pressure transmitted from the coil 2 through the tube 5. This gage has been found of great assistance in the operation of the superheater as it is highly sensitive in indicating changes in temperf'ature in the superheated steam, as changes in the pressure of the vapor in coil 2 depend upon changes in the temperature of the superheated steam. I also show at 44 a recording thermometer, the hot 'end of which is at 44 within the main 1. .The thermometer 44- is included in an electric circuit which circuit also includes a bell'45 adapted to be rung when the superheated steam reaches a set figure, thus giving an alarm to warn the fireman. The current for operating the bell is supplied from the batteries 45'. The use of the recording thermometer and the alarm bell is, of course,

supplemental to the use of the superheat limiting device.

The apparatus above described is set to operate at a temperature somewhat hi her than the average amount of superheat given by the superheater and should the superheat either accidentally or by design attain the temperature to which the device is set, the latter will act toprevent a further increase of'superheat. In the actual use of the device it has been found that by proper hand manipulation of the fires it is seldom called upon to act, but its use is, nevertheless, highly essential as it provides a safeguard against an excessive amount of superheat which might cause trouble in the power system. Such a device would be wasteful if applied as a regulator to be continually in action to maintain a given degree -of superheat, but when used as an emergency device for limiting the maximum amount of superheat the los in efficiency by admitting cold air into the setting does not militate against it. The limiting device is especially applicable to independently fired superheaters, as they are subjected to severe conditions when there is a sudden diminution in the rate at which steam is drawn through them or when there is a sudden stoppage in'the flow of steam. To make the described device operative there must be some steam flowing through the main 1. This is accomplished in practice by arranging the power units so that there is little possibility of all of them being shut down at once. In cases where the main units take all of the steam a connection will be provided whereby should it be necessary to suddenly shut down the units, a certain amount of steam 105 will be discharged to waste, thus insuring that some steam will flow through the superheater.

. In Fig. 7, I have shown my invention ap plied to a series boiler in which the feed water is delivered through a valved pipe 46 to the header 47. From this header the water flows through tubes 48 into header 49, and from the latter, the water and any contained steam fiows from one header to the next through the tubes of the series, and finally all of the water is evaporated and the steam on passing through the remaining tubes of the series is superheated and leaves the boiler through the steam main 1. In ad- 0 dition to the doors 33 for admitting air at the front of the setting, I may place doors 33 for admitting air at the side of the setting and another. 33 for admitting air at the rear of the furnace. In this arrangement, the rod' 17 is connected through a chain to a drum 51 from which a chain 52 leads to an arm on the shaft 35, the rotation of said shaft opening the front doors 33.

A second chain 52', from drum 51, is connected to a damper 53 in the blast flue leading to the stoker air-box 54. A third .chain 52 from drum 51, is connected to the .fiue damper 55, the parts being-so adjusted that the damper 55 will be moved to full open position when the damper 53 is partially closed. A fourth chain 52 from drum 51, is connected to a lever for operating the door 33 In the drawing the doors are shown open with lever 16 in its lowermost position. When lever 16 is raised the

doors

33, 33 and 83 will close and damper 53 will be moved to its full open position indicated by dotted lines.

In the operation of the series boiler the limiting device will be set to operate at the desired maximum temperature of the superheated steam, the device acting only in the case of an emergency to prevent a degree of superheat above the maximum. To I maintain the superheat under normal working conditions at a substantially set figure, the tires and the amount of water admitted to the boiler will be properly regulated. This regulation may be by hand or by a controlling device governed by the pressure gen erated in coil 2.

The series boiler shown may act as an economizer as well as a boiler and in this way combine an economizer, boiler and superheater. It may, however, be fitted with any other form of economizer through which the waste gases will be passed, and in most cases to an induced draft fan. Under conditions where an induced draft fan is employed, the superheat limiting device may be so arranged as to regulate the speed of the fan and thus limit the volume of cold air entering the setting.

It will be understood that by the expression superheatei as used herein, I mean to include any arrangement for generating or heating steam or gases whose temperature it .is desired to regulate or control, such for example as the series boiler illustrated in Fig. 7, as well as the usual type of superheater, in which the superheatertubes are separate from the boiler tubes. Y

In Figs. 8, 9 and 10, 1 have shown, on an enlarged scale, the mechanism illustrated in Figs. 1 and 7 for operating the power lever 16, this mechanismembodying certain features of construction differing from that shown in the diagrammatic Fig. 1. ater has been used as the evaporating agent in coil 2, in the practical use of the device, herein described. After the apparatus has been installed water is pumped into. the coil 2 through a valved pipe 58 having a remov-, able plug in its end, as shown. This filling takes place with steam flowing through the "main 1 and When the water has been heated it is blown out through the open end of pipe 58 and the apparatus then re-filled. By repeating this operation several times all 2, This point can be readily determined as the pressure falls quickly on first allowing the water to drip from pipe 58, whereas the moment the pressure corresponding to the temperature of the coil 2 is reached, there is no further fall in pressure. lVhen the ap-' paratus is set up and in operation the discharge outlet of the valve at the end of the pipe 58 is closed by the plug. The diaphragm chamber 59 must be filled with oil, or with water and oil, before the coil 2 is filled.

The chamber 59, as shown, is formed with a projection 59 to limit the downward movement of the diaphragm 60. Resting upon the diaphragm is a strut or post 61 which bears against a knife edge 62 carried by lever 63. The tension of spring 9 may be adjusted by a nut 9 to hold the lever 63 firmly against the stop9, and toprovide the requisite resistance to the upward movement of the strut 61. To the end of the lever 63 is attached the spindle 61 of a valve 61 shown on an enlarged scale in Fig. 9. Said valve is formed so that it will take its, position firmly on the seat 61 Both the seat 61 and the valve bonnet 61 may be readily taken out and replaced. WVhen the valve is opened by the pressure generated in coil 2, acting through diaphragm 60, strut 61 and lever 63, water under pressure will beadmitted through supply pipe 12 to cylinder 11, thereby moving piston '15. connected power lever 16 and rod 17 to effect the opening of doors as before described. As, shown in Fig. 10, a spring 65 is interposedbetweenthe end "of lever 63 and a supporting piece carried by the valve spindle 64'. lVhen valve 64 is closed, the

. lever 63 and spring 65 are in the positions shown in Fig. 10, so that a certain amount of play will be allowed between the lever and a piece 65 carried by the spindle, and having an enlarged head above the end of the lever. The initial upward movement of lever 63 takes up the lost motion and the continued movement of the lever will bring it against the piece 65.." to open the va ve.

The valve casing is formed with a passage 66 leading from the up er end of cylinder 14 to the discharge pipe 18. A portion of the water entering through pipe 12 is permitted to escape through the passage 66, the amount being regulated by a valve at the end of the threaded piece 66. The amount of water so escaping is much less than that which flows inward through the valve 64 so that the piston 15 will be forced downward irrespective of the fact that some of the water escapes through the passage 66. The leakage water which passes upward around the lower part of the valve spindle 64 escapes throu h a passage 67 into the waste pipe 18. W 'en the temperature of the steam flowing through the main -1 falls to a point which reduces the pres- 9 to lever '63. The connection between the end of lever 63 and the valve spindle 64 has been modified by attaching a piece 70 to the end of the lever by a screw, as shown, Also in this form the threaded piece 66- for throttling the water flowing through passage 66, is carried by a sleeve 66 The diaphragm and its casing have also been changed as indicated, that is, the member 71 in which the strut 61 is supported, is held by bolts 71, and in common with the first form described is of substantial construction in order to provide the rigidity and strength necessary for forming and maintaining a. good joint at the edges of diaphragm 72. As shown, in the enlarged view Fig. 15, the member 71 is formed with a projection 71 and the diaphragm is firmly held between said projection and a corre sponding depression in the base member 73. The lower end of strut 61 is seated in a cap 61 which fits into the centraldepression of diaphragm 72. The diaphragm has only a slight upward movement which is allowed for by providing a clearance as indicated at 72, the form of the diaphragm being of importance in the construction and operation of the apparatus. The amount that the cap 61' and strut 61 can rise is limited by allowing the proper clearance above the top of the cap and the] face 71 of member 71. A certain amount} of clearance is left between the top of the projecting stop 59 and the lower part of the diaphragm, this clearance being so regulated that should the strut 61 be forced downward to bring the diaphragm firmly against the stop, there will be no injury to the diaphragm.

Figs. 16 to 20 show a balanced valve for admitting water to the power piston, said vah'e comprising two

members

74 and 75 screwed together as indicated and having, respectively, two faces 74 and 75 of the same form and dimensions. faces seat against corresponding stationar faces 7 6 and 77. The member 78, on whic is formed the seat 76, is removably held b a pin 78 passed through its lower en By making the valve face 74 and its seat These valve .above the valve.

76 of the same form and size as the face 75 and its seat 77, the valve will be balanced and will require but little force to 'open and close it as compared with an imbalanced valve having the same capacity for the flow of water. Figs. 21 and 22 illustrate a further modification in the valve for admitting water to the power cylinder and the means for operatlng it. In this .form the valve 79 and its hollow stem 79 are preferably made in one piece. The valve casing is formed with a passage "12 leading from the pipe 12 which is connected to a source of water under pressure, said passage opening into a space in the casing below the valve so that an upward pressure willbe exerted by the,

water on the valve. In the lower part of the valve body are two ducts 80 through which water is permitted to flow into the casing above the valve. In the valve stem 7 9 are two sets of

ducts

81 and 82, the latter being normally closed, as shown in Fig. 21, by a spindle 83 connected to the end of lever 63, said lever being actuated by pressure generated in the coil 2 in the superheated steam main 1, as hereinbefore described. The spindle 83 passes through the valve stem 7 9 to near the lower end thereof, to provide a chamber 84. The ducts 81 afiord com-.

as the water is permitted to enter the space above the valve through the ducts 80 and into the chamber 84 through the ducts 81,

but cannot escape through the ducts 82. When the spindle 83 is raised by lever 63, the ducts 82 will be uncovered, allowing the water above the valve to discharge to the waste pipe 18 and thus relieve the pressure above the valve. When this occurs, the water pressure below the valve will open it, allowing the water from pipe 12 to enter the power cylinder 14, the valve in its opening movement causin its stem 7 9' to slide along the spindle 83. urrounding the lower end of the valve stem is a spring 86 between the valve and a cap 87 screwed into the casing, said spring being compressed when the valve is raised. .When the superheat is low-.

ered to an extent which will cause the lever 63 to fall, spindle 83 will be moved downward thus closing the ducts 82 and allowing the water pressure to build up in the space When the pressure is equalized, the spring 86 ,will close the valve.

In Fig. 21 the power piston is shown as returning to its normal position after the valve 79 has been closed, the .water above the piston during this time escaping through the passage 66 and thence to the waste pipe 18. A drain 14 near the bottom of the cylinder 14 conducts any water which may leak by the piston to the waste pipe 18.

Any water which leaks from the chamber above the valve 79 around the hollow stem 7 9, or through-the ducts 82, when closed by spindle 83, will flow into the chamber 85 and passage 85 and finally into the waste The spindle 83,.valve 79 and valve seat 79 are made of metal which will resist corrosion. The valve seat is formed with indentations 79 to permit engagement of a special tool for the insertion and removal of the seat. The inlet pipe 12 is provided with a strainer 12 to prevent any solid matter being carried in with the water which operates the power piston.

In the practical application of the apparatus shown in Figs. 1 to 10 it was found that the doors for admitting air into the setting would not at times close until after the temperature of the superheated steam had fallen 'a considerable amount below that v at which the doors were opened. This was times not close until the temperature had fallen to 47 5' F. Under most conditions of operation, as an emergency device, this fall in temperature of the superheated steam below that at which the doors were opened,

1 is not objectionable, as the fireman or attendant' can readily press 'down lever 63 after the superheated steam has been re-- duced to the desired degree and thus bring the apparatus to its initial condition in which it will remain until the temperature of the steam flowing over the coil 2 again reaches the temperature to which the apparatus is set. In order, however, that the doors for admitting air to the setting shall close immediately after the temperature of the steam flowing over the coil 2 falls below that at which the apparatusis set, I have ,devised the construction illustrated in Fig. 23. In this construction, the valve spindle 64' is connectedto the end of lever 63, the

valve 64 normally closing the endof the water inlet 88. When the valve is opened the water flows through passage 89 raising ball valve 89, thence into the chamber 90 from which the water is admitted into power cylinder 14. During the time that the valve 64 is open and the piston 15 descending, a portion of the water from chamber 90 flows through the outlet 66 into waste pipe 18, as in the other described constructions. The valve casing is formed with a vertical channel 91 which communicates with the chamber 92, in which the valve moves, through a duct 93 leading from the lower part of the chamber and controlled by a valve 93. That portion. of channel 91 which'is belowduct 93 is connected by a pipe 94 with the power cylinder 14, said dle 64.

When the temperature of the superheated steam flowing over coil 2 reaches that at which the apparatus is set to operate, lever 63 will be raised thereby opening valve 64 to admit water under pressure to the power piston, as before described. When water is admitted to chamber 92 a portion of it flows through duct 93 to the two branches of channel 91. .That portion flowing through the lower branch is conducted by pipe 94 to the lower part of cylinder 14 so that during the descent of the cylinder, so long as the outlet of pipe 94 remains open, the water so ads mitted will escape through the drain con nection 94 to waste pipe 18. The water'- which flows through the upper part of channel 91 is conducted through duct 95 to the chamber 96, above piston 97. There is, however, a comparatively low pressure in the upper part of channel 91 during the time that water flows freely through pipe 94.

When piston 15 reaches the end of its downward stroke it covers the opening from plpe 94 thereby stopping the flow of water through said pipe and causing the water to flow through the upper part'of channel 91 to chamber 96, the movement vof piston 97;.not being suflicient to completely'close duct 95. When the pressure in chamber 96 becomes great enough to overcome the resistance of valve 64, and if the temperature of the superheated steam flowing over coil 2 issuch that there is not too great an unbalanced force tending to maintain'the lever 63 in its upper position, the pressure acting on the upper side of piston 97 will close the valve 64. When valve 64 closes, ball valve 89 will close and piston 15 will move upwardso. as

to open the end of pipe 94, and alllparts-.,

that afi'ect the opening of the valve 64 will be restored to normal position, that is, valve.

64 will be automatically closed as soon as the piston 15 reaches the limit of its downward stroke and the piston 15will return to its original position at the top of the power piston, thus closing the doors in the setting through'the levers connected to piston 15 as heretofore descrlbed. Valve 64 will remain closed until the temperature of the superheated steam flowing over coil 2 exceeds the limit for which the apparatus is set. If, therefore, the opening of the doors for admitting air into the setting, or the manipulation of dampers, .as before described, causes the temperature of'the steam flowing. over coil 2 to be reduced the required degree, valve 64 will remain closed and the power piston will return to its normal position thus closing the air admission doors.

Any leakage from chamber 96 around spindle 64: passes into a chamber 98'below piston 97 and thence through the passage 99 to a waste pipe 100. A partition 101 separates chamber 98 from the chamber or water space 92 in which the valve 64 moves. Any leakage through the spindle opening in partition 101 will flow into chamber 98 and thus to waste pipe 100. A strainer 102 in the inlet pipe 88 prevents the entrance of 111% solid material into cylinder 14.

he form of apparatus shown in Fig. 23 nay be employed in a superheat regulating levice as well as in a superheat limiting de- 'ice. When used in connection with a uperheat regulating device the amount of uperheat would ordinarily be governed by other means than by allowing cold air to flow into the furnace or setting, the means employed being preferably of such a nature as not to lower the efliciency of the apparatus.

Vhat I claim and desire to secure by Letters Patent of the United States is:

l. A system for the purpose described, comprising a superheater and its setting, an outlet pipe for the superheated steam, a thermostat in said pipe, and means 'controlled by said thermostat for admitting air into-the setting when the temperatureof, the

- steam flowing over said thermostat to admit a fluid under pressure superheated steam flowing over the thermostat reaches a predetermined degree.

- 2. A system for the purpose described,

comprising a superheater and its setting, an outlet pipe for the superheated steam, a-

thermostat in said pipe consisting of a container fora volatile liquid, and means controlled by the pressure of the vapor in said container for admitting air into the setting when the temperature of the superheated container reaches a predetermined degree.

3. A system for the purpose described, comprising a superheater and its setting, doors for admitting air into the setting, an outlet pipe for the superheated steam, a thermostat in said pipe, a cylinder having a piston and connections from the latter to said doors, and means controlledby said to said cylinder to effect the opening of said doors. a

4:. A system for the purpose described,

comprising a superheater and its setting, an

outlet pipe for the superheated steam, a thermostat in said pipe, means controlled by said thermostat for admitting air into the setting when the temperature of the superheated steam flowing over the thermostat reaches a predetermined degree, said means comprising a cylinder and its piston, a pipe for admitting a fluid under pressure to said cylinder, and means for equalizing the pressure on opposite sides of the fluid -means for equalizing the pressure on opposite sides of said valve to restore it to its normal position upon a reduction in the steam temperature to a predetermined degree. a I

6. A system for thepurpose described, comprising a superheater and its setting, an outlet pipe for the. superheated steam, a thermostat therein, doors. for admitting air into the setting, and mechanism controlled by said thermostat to open thedoors when'the temperature of the superheated steam reaches a predetermined degree.

7. A system for the purpose described, comprising a superheater and its setting, an outlet pipe for the superheated steam, a thermostat therein, doors for admitting air into the setting, and mechanism controlled by said thermostat to open the doors when the temperature of the superheated steam reaches a predetermined degree, and counterweights to restore the doors to closed position.

8. A system f r the purpose described, comprising a superheated steam main, a thermostat within said main, a power cylinder having a valved pipe for admitting fluid under pressure thereinto, means for operating the valve in said pipe from said thcrmostat, said power cylinder having a closed piston and an outlet on the inlet side of the piston and through which a part of the fluid passes when it is admitted into and is under pressure in the cylinder and through which the fluid is exhausted, when the valve is closed, to permit the power piston to rei or L a said diaphragm, a power oylinder having a valved pipe for admitting fluid under pressure thereinto, means for operating the valve in said pipe by the movements of said diaphragm, said cylinder also having a closed piston and an outlet on the inlet side of the piston and through which a part of the fluid passes when it is admitted into and is under pressure in the cylinder and through Which the fluid is exhausted, when the ,valve is closed, to permit the power piston to return to its normal position.

10. A system for the purpose described, comprising a' superheated steam main, a thermostat in said main, a power cylinder having a valved pipe for admitting a fluid under pressure thereinto, means for operatessee"? ing the valve in said pipe from said thermostat, said cylinder having a closed piston and an outlet on the inlet side of the piston and through which a portion of the fluid is CH. ;harged when it is admitted to the cylinder and through which all of the fluid is discharged as the piston returns to its normal position, and means for returning the piston to such position.

In testimony whereof I have hereunto signed my name in the presence of tWo subscribing witnesses.

JOHN AaW. Dixon, EDITH CAMP.