US2699799A - Scavenging-air valve for soot blowers - Google Patents

Description

Jan. 18, 1955 R H WAGER 2,699,799

SCAVENGING-AIR VALVE FOR SOOT BLOWERS Filed Oct. 4, 1949 2 Sheets-Sheet` 2 /0 ETCEE- I N VEN TOR 3y iEBKDABEfe-rfi:17V/176.15,

ATTORNEYS United States Patent O SCAVENGlNG-AIR VALVE FOR SOOT BLWERS Robert Hudson Wager, South Orange, N. J. Appiication October 4, 1949, Serial No. 119,416 Claims. (Cl. 137-498) My invention relates to valves which are spring-opened to permit the passage of air or other fluid at a low pres sure but which are automatically closed when a fluid of much higher pressure is applied to the discharge side of the valve. More particularly the invention relates to valves of this character which are used to admit scavenging air to the heads of soot blowers of the fluid jet type when the blowers are not in use, but which may be used for other purposes where an automatic spring check valve for high and low pressure may be necessary.

The soot and dust which accumulates on the water tubes of steam boiler furnaces and the like are periodically removed by soot blowers usually of the steam jet type. Such a blower usually comprises a head supported on the boiler and connected to receive high pressure steam therefrom. Within the head is a valve which controls the admission of the steam to the blower element, the latter being a long pipe with many jet nozzles for directing jets of stam against the water tubes to be cleaned. The blower element is mounted for rotation so that the jets or blasts sweep over a bank of tubes to blow the soot therefrom,

' and the steam valve is operated in timed relation to the rotation of the element. When the blower is not being used the furnace gases containing sulphur and other corrosive ingredients, work back through the blower element into the head and cause considerable corrosion. lt is now common practice to admit scavenging air into the blower heads when they are not in use, and thus prevent the entrance of such corrosive gases. The scavenging air comes from the forced draft fans at the top of the boiler at a pressure of about onehalf to one pound or more per square inch and through a supply pipe connected to the head beyond the seat of the steam inlet valve. Since the steam pressure varies from about one hundred pounds up to about six hundred pounds per square inch, it has been a problem to provide between the air supply pipe and the blower head an automatic valve which would close and seal the low pressure air line when the high pressure steam is admitted to the element during the blowing operation and which would open to permit the low pressure scavenging air to low through the element f when the steam control valve is closed.

The primary object of my invention is to provide a valve of this character which will function effectively under such wide variations of pressures and which will be reliable and durable in use over a long period of time.

Another object is to provide in a device of this character improved means for preventing the valve and its seat from being injured when steam at a high pressure is admitted.

A further object is to provide means which will permit the same valve structure to be used eiective in connection with both low and high pressure boilers or the like.

Further objects and advantages will be apparent from the following description of the present preferred embodiments of the invention in connection with the accompanying drawings in which,

Fig. 1 is a vertical transverse sectional view through the head of a soot blower showing the application of the valve thereto,

Fig. 2 is a longitudinal section through the valve on an enlarged scale taken on the line 2-2 of Fig. 1 looking in the direction of the arrows,

Iig. 3 is a side elevation of the valve on an enlarged sca e,

Fig. 4 is a side view of the movable valve member,

Fig. 5 is an end view of the member shownin Fig. 4,'

Fig. 6 is a perspective View of a ring usable on the movable valve member when the valve is used in connection with low boiler pressures,

Fig. 7 is a longitudinal section through a modified form of the valve, and

Fig. 8 is a cross section of the modified valve on the line 8 8 of Fig. 7.

Referring more in detail to the drawings, Fig. 1 shows a side view of my improved valve, generally indicated by the numeral 1G, applied to one side of the hollow body 11 of a soot blower head 12 of a well known type, the valve having a scavenging air supply pipe 13 coupled to its outer end. The body 11 is shown as having on opposite sides bosses 14 with threaded bores so that the valve may be connected to either boss, the other boss being plugged. The rotatable blower element (not shown) is operatively connected to the head and steam is periodically admitted to it through a control valve, the steam entering the head through an inlet portion 15. The valve is of course positioned on the boiler side of the steam valve of the blower.

The valve 10 comprises a two-piece body or casing within which is the valve proper and a coil spring for moving the latter in a direction away from its seat. The casing consists of an elongated body portion 16 and a removable cap or attaching portion 1'7. These two sections or parts are preferably made of Monel metal and have hexagonal exterior surfaces as seen in Figs. 1 and 3 for engagement by a wrench. The outer or low pressure inlet end of the body 16 is reduced and internally screw threaded as at 18 to facilitate the connection of the air supply pipe 13. The inner end of the body 16 is also internally threaded at 19 to receive a reduced and threaded portion 20 at one end of the cap or bonnet 17. A threaded attaching neck 21 is formed on the other end of the cap or cover for engagement with a threaded openr ing 22 in the body 11 of the blower. A suitable gasket or sealing ring 23 is placed between the abutting portions of the body and cap as shown in Fig. 2.

The bore or passage through the valve body 16 has a major cylindrical valve chamber portion 24 in which the threads 19 are formed and a smaller portion 25 in which the threads 18 are formed. Between these portions is formed a beveled annular valve seat 26 for a valve 27 of the disk or poppet type. A guiding stem 28 is formed integral with the valve head or member 27 and has a cylindrical piston-like end portion with a sliding tit in an enlarged chamber-like portion 29 of the bore 30 through the cap 17. There is preferably a clearance of ten thousandths of an inch between the parts 28 and 29 so that the valve will be accurately guided toward and from its seat 26. The stem of the valve is formed between the head 27 and the end 28 with a portion 31 of reduced diameter; and between the portions 28 and 31 is an annular disk-like collar 32 having a diameter slightly less than the valve chamber or bore 24. This cylindrical collar 32 has a free sliding t in the valve chamber. A coiled compression spring 33 surrounds the valve head and stem portion 31, thrusting at one end against an annular shoulder 34 at the end of the bore 24 and one side face of the collar or iiange 32, as seen in Fig. 2. The spring biases the valve to its open position shown in Fig, 2 and normally holds the other `face of the collar against the adjacent reduced end 20 of the cap or cover. The collar thus serves as a stop and the spring insures the opening of the valve to admit the scavenging air to the blower when there is no high steam pressure in the body 11. Since when the blower is operated, the steam pressure in the blower head may be up to six hundred pounds or more per square inch, I so construct the device that this high pressure will not throw the valve to its seat with extreme violence. By making the parts as described and forming in the valve steam a plurality of longitudinal grooves or channels 35 which extend entirely through the collar 32, I iind I can avoid the valve hitting its seat too hard when high pressure steam is admitted to the head during the boiler blowing operation. As shown in the drawings four equally spaced grooves having a depth and a width of one-eighth. of an inch, extend from the end of the stem to a point beyond the collar 32 as seen in Fig. 2. The grooves 35 communicate Vmay. be used for other purposes and with various fluids with radial grooves 35a which extend transversely across the end-of the stem 28 as seen in Fig. 5. The purpose of the transverse grooves 35a is to enable the valve 27 to be ground to its seat 26 by means of a screw driver or similar rotatable tool inserted into the neck 21 while theparts of the casing remain connected. The portion 28 of the stem has a diameter of nineteen thirty-seconds ofl an inch, while the radially slotted collar 32 has a diameter of twenty-nine thirty-seconds, the overall length of the valve member being one and eleven thirty-seconds. The total cross-sectional area of the annular series of grooves in thestem portion 28 is greater than the crosssectional area of the three-eighth of an inch pipe l13 so that there will be no back-pressure and the scavenging air will pass freely through the valve when it is opened by the spring 33. It wili be noted that the grooves 35 are relatively large so that the low pressure air will pass freely through the device, and that said grooves substantially reduce the end area of the piston 28 exposed to the high pressure steam admitted into the device through the inlet 21, so that the valve is not driven against its seat 26 with damaging force. By actual tests i have found that when the valve is so constructed, it will operate efficiently on air pressure as low as a pound or less and steam pressure up to six hundred pounds and at temperatures as high as 850 F. However when the valve is used in connection with low pressure boilers having steam pressures of from one hundred to one hundred and fty pounds, I find the valve will operate more satisfactorily i'r` a Monel metal ring 36 (Fig. 6) is placed on the stern portion 23 against the adjacent at face of the collar 32, as shown in Fig. 2. This flat cylindrical ring covers the slots or portions of the grooves 35 which extend through the collar and hence the groove or slot area through which the steam passes to act on the valve head is reduced. The use of the restricting ring 36 permits the same valve to be used in connectionn with various steam pressures and renders unnecessary dinerent sizes or types of valves with openings of diierent areas through the collar.

It is believed the operation will be clear from the foregoing. However it may be repeated that the relatively weak spring 33 will insure the opening of the valve when there is no high pressure in the blower head. Thus the scavenging air will pass through the valve at all tunes when the blower is not being used so that the corrosive gases of the furnace will be kept out of the head and tne blower element. However when the blower 1s 1n operation the high steam pressure in the body 11 will act on the valve to close it, and there will be no leakage of steam if into the air line and the, boiler room.

While the invention is espec1ally well adapted for use as a scavenging air line valve for soot blower heads, 1t

whether gaseous or liquid, and with various pressures. In some cases it may be desirable to vary the tension of the valve opening spring. That may be accompllshed by providing a longitudinally adjustable abutment 37 for the spring on the stem between the head of the valve and the slotted collar as shown in Fig. 7. Screw threads 38 are formed on the portion 31a of the valve stem and the abutment 37 is in the form of a two-part internally threaded collar or nut which is adjustable on the threads to varythe tension of the spring 33a. The two sermcircular half sections of the nut 37 as seen in Fig. 8 are secured to each other by screws 39 which when 'tightened hold the nut in its adjusted. position. The spring abutment .nut or ring 37 has its edge formed with notches 49 corresponding Vto the slots 35a in the collar 32a and stem portion 23a to permit the passage of air. 'It will be noted that the screw threads 38 terminate shorthot the collar 32a so as to `form a stop to prevent the ring nut from closing the slots or openings in the collar. Since this modified form of the valve is otherwise the same `as the first form, the same reference numerals with the exponent a have been used.

From the foregoing, taken in connection with the accompanying drawings, it will be seen that novel and advantageous provisions have been made for carrying out the. objects of the invention, and while preferences have been disclosed, attention is invited to the possibility of making variations within the scope of the invention as claimed.

I claim:

l. An.y automatic check valve permitting low-pressure uid ilow in one direction and automatically closing f against high-pressure fluid flow in the opposite direction,

comprising an elongated casing provided at one end thereof with means adapted to connect the same with a source of low-pressure iluid and provided at theother end thereof with means adapted to connect the same with a high-pressure fluid receiver, said casing having a Huid passage therethrough from end to end, said passage being enlarged intermediate its ends to provide a cylindrical valve chamber having an annular valve seat adjacent `the lowpressure end of said passage, a cylindrical guide chamber of less diameter than said valve chamber positioned coaxially with said valve seat and an annular, radially disposed, imperforate stop wall between said chambers, a valve assembly in the enlarged portion of said passage including an annular valve head to engage said seat, a coaxial stem projecting from said head in the direction of the high-pressure end of said passage, an annular stop collar on said stem intermediate its ends and movable in said valve chamber for engagement with said stop wall, said collar having its periphery in substantially slidable engagement with the inner wall of said valve chamber, a cylindrical guide portion on the free end of said stem and slidably engaged with the wall of said cylindrical chamber and an annular series of longitudinal grooves formed in the peripheral surface of the cylindrical end portion of the stem, said grooves also extending entirely through said collar and outwardly through peripheral portions of, the latter to permit high-pressure fluid entering said other end of the passage to expand in said valve chamber, a valve-opening coil spring surrounding a portion of said stem to move said collar against said wall, said collar having .a at face opposed to said wall, and a flat cylindrical ring removably positioned on said cylindrical end portion of the stem between said at face and said wall to cover the portions of said grooves in saidV collar which open through said flat face and thereby restrict the passage of the high-pressure fluid past sai-:i co ar.

2. A scavenging air valve for soot blowers to give free ilow of low-pressure air in one direction but to close to high-pressure steam ilow in the opposite direction, comprising a casing having high-pressure and low-pressure inlets and between said inlets a cylindrical valve chamber and a cylindrical valve-guiding chamber concentri cally disposed, said valve-guiding chamber being of less diameter than the valve chamber, said valve-guiding chamber having one end in open communication with said high-pressure inlet, there being an annular stop wall at the other .end of said valve-guiding chamber where it communicates with one end of said valve chamber, the other end of said valve chamber being in open communication with said low-pressure inlet and having an annular valve seat concentric with said chambers, a valve assembly in said casing made of metal and in one piece, said assembly having a stem with an integral disk at one end forming a valve head to coact with said seat, with an integral elongated cylindrical piston at its other end of a diameter to slide in said valve-guiding chamberV to support and guide the valve assembly and with an integral annularV radially projecting collar at the juncture of the inner end of said piston with the stem, said collar being cylindrical and having a diameter slightly less than the diameter ofthe valve chamber and also having one face in opposed relation to said stop wall and its other face in opposed relation to vsaid other end of the valve chamber, there being in said valve assembly an annular series of longitudinal grooves which extend throughout the length of said piston and into a portion of said stem and which aline with and communicate with a corresponding seriesof radial slots in said collar, the total cross-sectional area of saidv grooves being at least equal to the crosssectional area of said low-pressure inlet to allow'free tlow of low-pressure fluid through the casing when the opening movement of the valve is stopped by the engagement of said collar with said stop wall, and a coil spring in the valve chamber surrounding the valve disk and stern and thrusting at one end against said collar and at its other end against said other end wall of the valve chamber.

3. A valve for the purpose Yset forth composed of a casing having detachably connected body and cap sectlons, a one-piece valve assembly in said casing and a coil spring lto actuate the -valve assembly in one direction, the body section-having a cylindrical valve chamber opening through one end with internal screw threads at said end, the other end of the body section having a low-pressure uid inlet with a valve seat concentric with said chamber, the cap section having at one end external screw threads to engage said internal threads and also having a cylindrical valve-guiding chamber concentric with and opening into said valve chamber, the extremity of said one end of the cap member forming an annular stop wall at the juncture of the two chambers, the other end of the cap member having a high-pressure uid inlet which opens into said valve-guiding chamber, said Valve assembly being formed of metal in one piece and comprising a stern having at one end an integral disk forming a valve head to coact with said seat and having at its other end an integral cylindrical piston of a diameter to slide in said valve-guiding chamber, said stem also having at the inner end of said piston a cylindrical radially projecting collar with one face disposed in opposed relation to said stop wall, said stem being further provided with an annular series of longitudinal grooves which extend from the end of said piston and past said collar, the latter having an annular series of radial slots which register with said grooves, said collar also having a diameter slightly less than that of said valve chamber, the total cross sectional area of said grooves being at least equal to the cross sectional area of the low-pressure inlet to allow free i-low of low-pressure fluid through the casing when the valve is open and said collar is engaged with said stop wall, said coil spring being disposed in said valve chamber around the valve head and a portion of the stem, and thrusting at one end against said collar and at its other end against said other end of the body section of the casing.

4. In a valve of the type permitting low-pressure uid flow in one direction and automatically closing against high-pressure iluid flow in the opposite direction; an elongated casing having a high-pressure inlet at one end, a low-pressure inlet at its other end, a cylindrical valve chamber between said ends in communication with said low-pressure inlet, an annular valve seat in said chamber adjacent said low-pressure inlet, and a cylindrical valveguiding chamber coaxial with said seat and in communication at one of its ends with said high-pressure inlet and at the other of its ends with said valve chamber, said Valve-guiding chamber being of less diameter than said valve chamber, to provide an annular radially-disposed stop wall in said casing at the juncture of the two chambers, a valve assembly in said valve chamber including a stem having at one of its ends a disk forming a valve head engageable with said seat and at its other end a cylindrical piston slidable in said valve-guiding chamber to support and guide the valve assembly, and an annular stop collar on said stern at its juncture with said piston, said collar being disposed in said valve chamber in opposition to said stop wall and having its periphery slightly spaced from the wall of said valve chamber, the free end of said piston being at all times exposed to uid pressure entering said high-pressure inlet, said piston having in its periphery an annular series of longitudinal grooves extending from its free end and opening at all times into said valve chamber between said valve disk and said collar, the latter having an annular series of radial slots forming extensions of the grooves in said piston, said grooves reducing the end area of the piston and permitting high-pressure fluid to pass the piston end and expand in said slots and in the valve chamber in rear of said valve disk, said collar having a at face opposed to said Wall,

together with a flat cylindrical ring removably positioned on said piston between said at face and said wall to cover the portions of the slots in said collar which open through said Hat face and thereby restrict the passage of the high pressure fluid past said collar, and spring means in said casing to urge said valve disk away from its seat.

5. ln a valve of the type permitting low-pressure fluid ilow in one direction and automatically closing against high-pressure fluid ow in the opposite direction; an elongated casing having a high-pressure inlet at one end, a low-pressure inlet at its other end, a cylindrical valve chamber between said ends in communication with said low-pressure inlet, an annular valve seat in said chamber adjacent said low-pressure inlet, and a cylindrical valveguiding chamber coaxial with said seat and in communication at one of its ends with said high-pressure inlet and at the other of its ends with said valve chamber, said valve-guiding chamber being of less diameter than said valve chamber to provide an annular radially-disposed stop wall in said casing at the juncture of the two chambers, a valve assembly in said valve chamber including a stem having at one of its ends a disk forming a valve head engageable with said seat and at its other end a cylindrical piston slidable in said Valve-guiding chamber to support and guide the valve assembl and an annular stop collar on said stem at its juncture with said piston, said collar being disposed in said valve chamber in opposition to said stop wall and having its periphery slightly spaced from the wall of said valve chamber, the free end of said piston being at all times exposed to fluid pressure entering said high-pressure inlet, said piston having in its periphery an annular series of longitudinal grooves extending from its free end and opening at all times into said valve chamber between said valve disk and said collar, the latter having an annular series of radial slots forming extensions of the grooves in said piston, said grooves reducing the end area of the piston and permitting high-pressure :Huid to pass the piston tend and expand in said slots and in the valve chamber in rear of said valve disk, and spring means in said casing to urge said valve disk away from its seat, said spring means includes a coil spring surrounding said stem and thrusting at one end against the adjacent end of said valve chamber, said stem being externally screw threaded between said Valve disk and said collar, and an adjustable abutment against which the other end of said spring thrusts to move said valve disk away from its seat, said abutment including an internally screw threaded collar engaged with said screw threads and composed of two abutted semi-circular half sections and screw threaded fastenings clamping said sections together on the threaded portion of said stem.

References Cited in the le of this patent UNITED STATES PATENTS 351,159 Brengel Oct. 19, 1886 314,216 Barker Mar. 24, 1895 746,402 Sutton Dec. 8, 1903 767,098 Belden Aug. 9, 1904 2,136,898 Thomas Nov. 15, 1938 2,204,757 Henze June 18, 1940 2,245,271 Guile June 10, 1941 2,279,976 Faust Apr. 14, 1942 2,307,949 Phillips Jan. l2, 1943 2,357,321 Fuller Sept. 5, 1944 2,554,390 Stevenson May 22, 1951

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