US2307963A - Blowoff valve system - Google Patents

Description

Jan. 12, 1943. w. E SHAFER 2,307,963

BLOW-OFF VALVE SYSTEM- Filed July 10, 1939 2 Sheets-Sheet l I NVEN TQK WI/M015 fit/er A O K EY Jan. 12, 1943. w. E. SHAFER 2,307,963

BLOW-OFF VALVE SYSTEM Filed July 10, 1939 2 Sheets-Sheet 2 INVENTOR. W/Y/A'M: 5394/ ATTORNEY Patented Jan. 12, 1943 UNITED STATES PATENT OFFICE BLOWOFF VALVE SYSTEM William E. Shafer, San Francisco, Calif. Application July 10, 1939, Serial No. 283,634 1 Claim. (Cl. 122-382 I'his invention relates to a valve system, and particularly to one that is utilized for ejecting material from the bottom of steam boilers, such as locomotive boilers.

Blowing olia boiler may be required for any of a number of reasons.

, For example, excessive foaming in a boiler may be relieved by the escape of material through the blow-off valve; or the Valve may be used simply to eliminate undesired and harmful muddy material. This matter, gradually precipitated from the water over periods of use of the boiler, may after a time cause serious consequences or may aggravate other harmful effects.

Ditch, the operation of the blow-oii valve is inane automatic, in response to such phenomena as excessive foaming.

It is one of the objects 'of this invention to provide a simple and inexpensive blow-off valve that may be operated either manually or automatically. When the operation of blowing off is to be accomplished by a manual control of the valve, the control elements should be located so as to be within easy reach of the engineer in charge of the boiler. Thus, when the blow-oif valve is applied to a locomotive boiler, the control elements should be located in the locomotive cab, preferably on the back head of the boiler. In case other than locomotive boilers are involved, the control elements may be located in the most convenient location. It is also prefera'ble to be able to utilize the steam pressure of the boiler for operating the valve; however, the design of a valve that can be efliciently operated by the high pressures encountered would be complex and expensive. It is another object of this invention to make it possible to perform the valving operations by the aid of pressure derived from the boiler, without danger of serious transient pressure phenomena.

It is another object of this invention to obviate the necessity of any non-metallic or other kind of packing, or seals in the blow-oii valve. In this Way, there is no danger of deterioration due to the effect of the moisture carried by the steam.

It is still another object of this invention to ensure against the accumulation of moisture in the valve system, whereby the danger of the valve being rendered inoperative during freezing temperatures is eliminated.

This invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of one embodiment of the invention. For this purpose there is shown a form in the drawings accompanying and .iorming part of the present specification. This form will now be described 'in detail, illustrating the general principlesof the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best defined by the appended claim.

Referring to the drawings: H

Figure 1 is a fragmentary view of one type of installation in connection with which the invention may be used, of a locomotive type boiler; U

Fig. 2 is an end View of the boiler illustrated in Figure 1;

Fig. 3 is an enlarged sectional view of the blow-cit valve;

Fig. 4 is a still further enlarged fragmentary sectional View of the drain valve utilized in connection with the system; and V Fig. 5 is a View similar to Fig. 3, but showing the blow-off valve installed in a position that is inverted with res ec io the position of Fig. 3.

In Figure 1 the boiler I is indicated as having a water line 2. Only the fire box end of the boiler is shown, it being understood that there is a mud ring 3 disposed at the bottom of the water "space which surrounds the fire box 4.

In order to blow off the boiler, as required foreiia'mple, upon excessive foaming, or to eject accumulated mud above the mud ring, use is made of a blow-off valve 5. This blow-off valve may be controlled manually or automatically. If it is manually controlled it is preferably arranged to be controlled from adjacent thefire box end of the boiler I where the water glass, injectors and other apparatus incident to the operation of the boiler are commonly located. For that reason, the control valves may be placed conveniently on the back head of the boiler l.

The blow-oil valve structure is indicated most clearly in Fig. 3. It includes a valve body 6, preferably made of steel or other metal that can withstand the high pressures encountered in locomotive or other boilers. This body 6 has integiral internally threaded flanges 1 and 8. The flange 'l is adapted to receive the threaded end of a conduit 9 leading from the boiler just above the mud ring. Similarly, the flange 8 is adapted to receive the threaded end of an outlet conduit HI leading to a discharge point. Inside of the flange 1 there is provided a seat or shoulder H for the accommodation of a threaded strainer.

ring l2 oi the usual construction. This strainer ring is thus interposed in the intake passages of the valve body.

for example, the fire box end.

The interior of the body 6 is divided by a partition I l. This'partition M has a horizontally extending'portion I3 through which there is a port I5. The upper edge of the port is beveled to form a valve seat iii. Communication from the inlet to the outlet is afiorded through this port l5.

Cooperating With the valve seat Iii is a closure member I! in the form of a circular collar carried on a valve stem I8. This valve stem I8 has an upwardly directed extension I9 guided in a boss 20. This boss is shown as integrally formed in a cap 2I threaded to the threaded extension 22 of the body 6.

If desired, a compression spring 23 can be inserted between the cap 2! and the top of the closure I'I urging the closure to the closed position illustrated in Fig. 3.

The stem I8 is extended downwardly through V a projection 24 shown as integral with the valve body 6. The stem I8 has a sliding fit inthe projection 24.

When the closure I? is lifted from its seat I6, the bloW-ofi valve is opened and ejection of material occurs through the aperture I5 and the outlet conduit I0. When the valve closure I? is seated, this flow is interrupted. When the valve is closed, the pressure of the boiler acting through the intake 9 acts upon the closure I! to hold it firmly on its seat.

In order to operate the valve to open and close it, use is made of a fluid pressure device including a piston and cylinder mechanism. Thus, for example, the stem I8 carries a piston 25 operating in a pressure cylinder 2%. This piston 25 has an upper surface contacting the annular shoulder 21 formed on the stem IB by reducing the size of the stem where it passes through the piston 25. This reduced portion 28 may have a threaded extremity 29 for the accommodation of a nut 30 and a crown check nut 3|. The cylinder member 26 has a head 32 threaded to engage the body extension 24. The effective area of the piston 25 is purposely made substantially larger than the area of closure II, so as to ensure that the force acting on the piston 25 will be sufficient to move the closure to open position. In order to ensure a fluid tight fit between the cylinder 26 and the body extension,

this body extension is shown as being provided with a built up shoulder 33. This shoulder may be formed of bronze, deposited as by oxyacetylene welding, around the extension 24, and forms a seat adapted to be engaged by head 32. A sealing efiect is thus obtained between the cylinder 26 and the valve body 6, without'the aid of any yielding gaskets, that would deteriorate rather rapidly.

The lower end of the cylinder 25 is also threaded for the accommodation of a cylinder cap 34. The threads are also purposely made sufficiently tight so as to obviate the necessity of any gaskets or packing.

It is apparent that the piston 25 divides the cylinder space into an upper chamber 35 and a lower chamber 36. Fluid under pressure admitted to the lower chamber 36 would urge the piston 25 upwardly to open the valve. Conversely a pressure applied in the upper chamber 35 will act to close the valve. If necessary the piston 25 may be provided with one or more metallic spring piston rings such as 37.

In order to lead fluid under pressure into the chamber 35, use is made of aconduit 38 having a nipple 35 threaded into a port 40 in the head 32, and leading downwardly into the chamber 35. Similarly a conduit ll is provided for leading fluid under pressure into the chamber 36. This conduit also is provided with a nipple 42 threaded into the cap 34.

It is essential that when the valve closure I1 is lifted to open the blow-off valve, there be no escape of fluid from the chamber 35 past the stem 58 into the valve body. For sealing the valve closure structure with respect to the valve body when the valve is fully opened, use is made of a tapered shoulder 48 formed in the bottom of the extension 24, and surrounding the stem I8. This tapered shoulder 58 serves as a seat for the tapered surface 49 formed on the upper surface of the piston 25. When the valve is opened, the tapered surface 49 seals against the shoulder 48, thus effectively isolating the operating fluid from the valve body.

A convenient source of pressure for operating the b-low-ofi valve is the boiler I. However, this pressure isusually too high for effective operation, as serious water hammer effects might result. By an arrangement to be hereinafter described, the boiler pressure is utilized without these attendant deleterious effects.

The conduits 38 and GI lead upwardly to some desired position, for example into the cab of a locomotive, where they are readily accessible for operation. They are there joined through horizontal extensions 43 and M (Fig. 2), to a conduit 45 (Fig. 1), leading into the boiler I, preferably below the water line 2. The conduits 33 and 4|, as Well as their extensions, may be relatively small, for example, inch copper tube or pipe, of suitable thickness. By an appropriate arrangement of valves it ispossible topass fluid under pressure to either one of the two conduits 38 and 4 I. For this purpose the control valves 46 and 41 which may be ,4 inch pipe size, are indicated in Fig. 2, respectively controlling the admission of the fluid to conduit 4| and conduit 38. These valves may be either manually controlled or automatically controlled in response to conditions of operation of the boiler, such as excessive foaming or the like.

It is apparent that in view of the high pressure, of the order of several hundreds of pounds per square inch, existing in the boiler I, the opening of the control valve to either one of the two conduits produces a sudden drop in pressure in the medium entering the conduit, and therefore the fluid medium in the conduit would be mainly in the form of steam. However, the conduits 38 and AI are both made of suifici-ently small cross section and are purposely arranged to be quite well cooled, so that a substantial amount of the fluid is condensed into water befor entry into the cylinder 26/ In this way the blow-oil valve is operated by hydraulic pressure rather than by steam pressure; and thusa cushioning effect is produced. Furthermore, the hydraulic pressure may be excessive, with attendant injury to the valve system. In order to ensure that the pressure within the cylinder spaces 35 and 36 may be reduced to avoid these effects, pressure reducing vents are provided, which are continuously open.

For example, connecting to the conduit ll by the aid of a T connection Ell, there is downwardly directed nipple 5i connecting to a reducer 52. This reducer has a horizontal vent 53 which is continuously open, and which serves effectively to reduce, by a substantial amount, the pressure transmitted to the lower side of the piston 25.

aeozoee This is due to the restricted escape of the fluid through the vent.

The reducer fitting 52 is shown as having threaded into it a drain valve structure 54 shown most clearly in Fig. 4. This valve structurecontrols a drain aperture 55, which is placed below the lowest point of the conduit 4|. When fluid under pressure is present in conduit 4|, the check valve closes, closing the drain 55. As soon as the fluid pressure is released by closing valve 41 (Fig. 2), then the check valve is allow-ed to open and the drain 55 drains whatever accumulated liquid there may be in the cylinder chamber beneath the piston 25. The drain aperture 55 is purposely placed at the lowest point of the conduit 4| so that complete drainage is effected. Therefore the possibility of freezing in cold weather, that might interfere with the valve operation, is prevented.

The drain valve structure may take any conventional form. In the present instance the valve structure 54 includes a tapered valve seat 55 adapted to be closed by a closure head 51 mounted on the stem 58. The lower portion 59 of this stem is slidably mounted in an aperture in the lower wall of the valve. A compression spring 60 is interposed between the bottom of the valve 54 and the annular shoulder 6| formed beneath the upper portion 58 of the stem. This compression spring '60 urges the valve closure 51 to open position when pressure in the conduit 4| is released. A threaded apertured member 62 closes the top of .the valve and limits the upward movement of the closure 51.

A similar structure is included in the conduit 38. Thus the T fitting 63 provides a connection for the downwardly directed reducer member 64 with a constantly open vent '65. The lower end of the reducer supports the drain valve structure 56, which may be identical with the structure illustrated in Fig. 4.

The mode of operation is apparent from the foregoing. Assuming that th blow-off valve is in the closed position of Fig. 3, and that it is desired to open it. for this purpose the valve 41 (Fig. 2) is opened, valve 46 being left in closed position. Opening the valve 41 causes fluid at initial high pressure and temperature to enter the conduit 4|. Inthis conduit it expands and due to the reduction in pressure, any liquid present is converted or flashes into steam. However. a substantial cooling effect is produced by transfer of heat through the walls of the conduit 4| at a rapid rate. The conduit 4| is for this purpose led outside of the cab, in a comparatively cool location. The steam therefore partially condenses and the resultant liquid or condensate then is forced by the boiler pressure into chamber 36. A part of the fluid, however, escapes through the vent 53. The effective pressure in chamber 35 is therefore materially reduced and the valve opens slowly and mainly by a cushioned hydraulic action. At the same time the pressure in conduit 4! urges closure 51 of the check valve 54 against its seat, closing the drain 55. As soon as the valve 41 (Fig. 2) is closed, the fluid slowly leaks through the open vent 53 and the spring 23 returns the closur H to the closed position.

However, it may be desirable to pass liquid pressure to the cylinder chamber 35 to provide a strong closing force for the valve. If that is desired, the valve 45 (Fig. 2) is opened and the piston 25 is then urged downwardly in the same manner as it had been urged upwardly for the opening operation. The vent 65 and the check valve 66 operates as before. When the blow-off valve closure |1 reaches its seat, the, valve 46 maybe closed, and the accumulated liquidin the conduit 38 is permitted to flow through the drain in the check valve 66.

In order further to ensure that the accumulated moisturev in the chamber 35 will be drained, a downwardly'sloping drain aperture 51 (Fig. 3) is provided from the chamber 35. This drain '61 may connect with an upwardly directed groove 68. When piston 25 is in its uppermost position, the drain 61 is closed by the piston. As soon, however, as the piston' recedes, the drain 61 is effective to remove all condensed fluid above the piston 25.

The system has been described as being operated by the opening and closing of control valves 46 and 41 illustrated in Fig. 2, which control the passage of fluid from the boiler l. However, it may be necessary to open and close the blow-ofi valve when there is no pressure in the boiler, as for example for cleaning out the boiler. For that purpose it may be advisable to provide a supplemental connection 69 (Figs. 1 and leading to an independent source of pressure, such as air pressure for inducing a draft in the stack, or a supplemental source of steam pressure. By the aid of appropriately positioned valves it is possible for the operator optionally to connect the conduits 38 and 4| to either the boiler I or to the conduit 69. Thus for example valve 10 is shown in conduit 69 which is to be closed when the pressure in boiler is utilized. The valve 1| in the conduit 45 leading to the boiler l is opened. If, however, it is desired to utilize the supplemental source of pressure, the valve 1| is closed and the valve 10 is opened.

To facilitate lubricating the blow-oil valve, a pair of plugged Ts 12 and 13 may be provided, respectively in conduits 38 and 4| (Fig. 2). These Ts may be opened when valves 46 and 41 are both closed, whereby the introduction of lubricant may be effected through the open Ts. Then the plugs may be reinserted and the system is again rendered capable of operation by appropriate manipulation of the control valves.

It may be desirable at times to invert the position of the blow-off valve. Such an installation is illustrated in Fig 5. In this case the conduit 4| is shown as before, leading to the cylinder space 36. The cylinder space 35 is connected to the conduit 38. As before, the vents 53 and are utilized to reduce the pressure effective in the cylinder spaces. In this case the drain valve structures 54 and B6 controlling the drains from the conduits 4| and 38, are again placed in as low a position as possible. However, in order to assure drainage from the chamber 35 (which is now above the piston 25) a drain aperture 14 may be provided for this space. This drain aperture operates similarly to the drain aperture-B1 of Fig. 3.

The system is reliable in operation. The blowoif valve is efiectively controlled by hydraulic pressure, which is very much less than the pressures existing in the locomotive boiler. By ensuring that a substantial part of the fluid operating the valve is condensed by cooling through the conduits 38 and 4|, the blow-off valve is operated in a smooth, even manner.

It is to be understood that vents 53, 65, 61 and 14 are each of small size of the order of inch diameter.

What is claimed is:

In a blow-off valve structure for a steam boiler, and adapted to be operated by the pressure in said boiler, a valve body having a valve seat, a closure cooperating with the seat, a cylinder acting to operate the closure in response to the boiler pressure on the condensate, and means providing a constantly open vent from the chamber to reduce the pressure of the condensate in the chamber.

WILLIAM E. SHAFER.

Images