US1783368A - Safety blow-off for boilers - Google Patents

Description

Dec. 2, 1930. ROWLAND 1,783,368

SAFETY BLOW OFF FOR BOILERS Filed Aug. 10, 1926 gmenfoq Louis D. Rowland Patented Dec. 2, 1930 UNITED STATES PATENT OFFICE LOUIS D. ROWLAND, OF SEATTLE, WASHINGTON SAFETY BLow-orr Foa BOILERS Application filed August 10, 1926. Serial No. 128,480. r

connections, to the end that such connections, which are wholly or partly-outside of the boiler shell and'setting, maybe isolated from the boiler automaticallyin caseof' a rupture in the external connections,'thus lessening the danger to persons and the damage to property ensuing from such ruptures.

The principles involved in my invention and a preferred manner of carrying it out, have been illustrated in the accompanying drawings and will be set forth in the follow- "ing specification. The features of the same which I believe to be new and upon which I desire to secure a patent will be specifically a 0 pointed out in the claim;

Figure 1 illustrates my invention as applied to a steam boiler, the rear end ofa boiler and its setting being shown in section.

Figure 2 is a verticalsection through the i r cut-off valve and the connection ofthe blowoif pipe with the boiler. Y V

Figure 3 shows in'section, the'c ut-ofl' valve employed in connection with the circulation pipe whichfis associatedwith the boiler blo in the blow-oif connections, or in the external P circulating system connected therewith, this frequently causing loss of life, aswell'as property damage. It is the object of my presentinvention to provide means whereby the 55 40 frequency of suchruptures willbemuch'reduced and whenthey do occur'danger and damage will be prevented.

To this endI provide means constant circulation of fwaterthrough' .t e

i blow-off-;connections,'-in such al man'ner that the" deposit of" sediment in the blow o ff connections, with its 'attendantresult of over i heatingand burningout, is largely,' if not" f whollyeliminated To-eliminate the danger and damage cause'dby a rupture in the" ex for securin a ternal connections, if and when it does occur, I provide valves so arranged that they are normally held open by the internal boiler pressure, and notby any mechanical or re silient means, so that whena rupture occurs the reduction in pressure in the blow-off pipes,

externally of these valves, will applypressure to them which is the resultant of the internal pressure, acting to close them, and the external pressure, oppos ng the internal pressure, and in such manner that they will autoinatically close and prevent further escape of water. This takes advantage of the strongest and most destructive force available, and directs it toward the end of making theboiler secure from destruction because of mechanical defects. Thus, noreliance is placed 11 the functioning of mechanical parts, trips, springs, or the like, which, through a period ofinactivity, may deteriorate and fail at the crucial moment to function. To make the device entirely automatic, the connections and valves are so arranged that, following blowing ofi (duringv which time the valve will close to prevent communication between. the circulating system and the boiler shell, unless forcibly held open), the valves, or an valve which is in the circulating system an which has been closed, will automatically reopen.

The boiler illustrated, has a cylindrical shell 11, heads 12 and return smoke flues 8,

being of a standard type which is widely used.

This type of boiler has been shown because of its wide use and not that my invention is in any sense limited in its application to this or anyother typeof boiler. The usual working water level isshown at W. The masonry setting at therear end of the boiler is shown at 6 andthecombustion chamber 7 which connects the tubes 8 with the furnace.

' The blow-off valve 13 is outside of the boiler setting and is connected with the lower side of the boiler through the blow-off pipe 9. These parts'may' be of any usual or suitable type; The preferred manner of connecting the blow-'oifpipe' with the boiler is by, an elbow 9' and a nipple 10, and preferably also, a flange plate 3.

"The nipple 10 is illustrated as projecting upward-in the boilerto form the cylinder or sleeve, 10 of the cut-off device. This unitary feature of the nipple and cylinder, while convenient and an approved construction is in no sense constructionally essential, so far as the present invention is concerned.

The cylinder or sleeve 10 has ports 15 in its walls, so positioned that their lower margins are as low or lower than the inner surface of the boiler shell. This is desirable to insure complete drainage of the boiler therethrough, although not essential in the functioning of my device as a safety cut-off.

Mounted to slide freely and yet quite close ly in the cylinder 10 is a cut-off piston or sleeve 16 of a length that, when in its lower- -most position it will close the ports 15. It

is provided with a limiting stop, this as illustrated being in the form of a flange 16, the same being'an extension of the head which closes the upper end of the piston.

The head of the cut-off piston or sleeve 16 has ears 17 to which a rod 18 is connected by a pin 17. This rod and its extension 18. extend upward and through the top wall of the boiler, a stufiing box or gland 19 being provided to permit free limited reciprocation sufiicient to move the cut-oif piston between open and closed positions. A threaded coupling 18" or an equivalent means is employed to connect the two sections of this rod.

The upper, outer end of the section 18 is connected with a lever arm 20, pivoted at 21 to any convenient support. That shown is a bracket arm 22 mounted on the boiler shell. The arm 20 which is approximately in a horizontal position, may carry a weight 23 adjustably fixed thereon as to its distance from the pivot. A spring 23 is illustrated, its function being to act upon the arm 20 to oppose downward movement of the valve 16 to some extent, but less than sufiiclent to insure its seating under conditions to be described later.

In other words, the spring 28 is a buffer spring solely and except as its use for this purpose may be desirable, it may be omitted altogether. It is ordinarily made strong enough to overcome the weight 23', so that it will also function vto maintain the valve raised when the boiler pressureis quite low, as when the fire is extinguished, but normally the valve will be held raised solely by the boiler pressure, as will be explained later, and

.the spring23 will ordinarily have no function except as a buffer or cushion.

Normally this cut-off piston 16 is raised sufiiciently to fully open the ports 15,01 to the point indicated by dotted lines in Figure 2. The total pressure on the bottom of this piston is inexcess' of the pressure on its .top by. anamount equal to the crosssection of the rod 18ywhereit passes through the shell 11, times-theefiiective boiler pressure, and at ordinary working pressures thisdifference in pressure 1s more than sufiicient to support :the weight of the'valve 16, rods 18 and 18, and the arm 20 and weight 23. By adjusting the weight 23 upon the arm 20, the desired balance may be obtained wherein the cut-off piston is nearly but not quite on a balance between the opposed forces. Any suitable stop (not shown), may engage the rod 18, the arm 20, or any other part of the control mechanism of valve 16, to limit the valves upward movement.

It is evident that with the device so adj usted, if the blow-off valve be opened, or a rupture occur anywhere in the cut-off connections, the external pressure, which acts upon the lower side of the cut-off piston 16, will be reduced to less than that required to counterbalance-the downward pressure thereon, so that it will be quickly forced downward. This automatic action is due solely to a change in the relative values of the two forces acting upon the valve, one acting downwardly to close it, and the other acting upwardly to oppose the first, and being normally sufliciently greater than the downwardly acting force to support the weight of the valve and its controls because of the greater area presented to its action. The change in the values of these forces occurs through opening the blow-ofi' valve 13 or through opening any external connection to the blow-ofi" line 9 to the atmosphere, thus destroying the upwardly acting force, and leaving only the downwardly acting force, which promptly closesthe valve. To prevent such action when it is desired to blow-off the boiler, manual controlof the cut-off piston is provided. For this purpose I have shown the arm 20 as having a right angularly placed extension 20and a rod or cord 37 secured thereto and extended to a convenient point for manual operation.

To prevent deposit ofsediment inthe blowolf pipe 9 and the resulting overheating and burning whichleads .to a rupture, I provide a circulation "connection therewith. This is in the form of a riser-pipe 24,-placed outside of the boiler setting, or where it is materially cooler than the boiler, and'a pipe 25 connecting this riser pipe with the boiler a suitable distance below the usual water level. It is evident that the water in the pipe 24 will be cooler than that in the boiler, which will induce a circulation downward in said pipe 24;,and thence inward thru pipe 9 to the boiler, thus preventing stagnant water in the blow-off pipeand the deposit of sediment therein. These pipes form a thermosyphon system.

In using such a circulation connection in a of my invention it is evident that it is nec -.essary to'provide an automaticallyoperable cut-01f for this pipe, operated by a reduction of pressure in the blow-off device. Otherwise,

-- closureof the valve 16 would not prevent escape of water. and. steam throughthe' pipei25 to the source of the rupture. To this end I have provided a stop disk or valve 26 carried just within the head of the boiler upon a stem 28 which is reciprocably mounted within the pipe 25.

This valve seats upon a short sleeve 27 inserted in the end of pipe 25 and is enough smaller than pipe 25 to permit its insertion from without the boiler.

The elbow fitting 24 which connects the pipes 24 and 25 has a stulfing box or gland 29 through which the valve stem extends with out the fitting. A stop collar 30 secured to' the projecting portion of the stem limits the opening of the valve 26. The outer edge of the stem 28 carries a yoke 34, or equivalent means whereby a spring or springs 31, carried by supports 32, from the gland case 29, may be enabled to counteract the otherwise unbalanced pressure represented by the crosssectional area of the stem 28. It will also automatically open valve 26 when pressure in the boiler drops. A nut 35 screwing upon stem 28 permits ready adjustment of the active force of the springs. A knob or handle 36 permits hand movement of the valve. The inner end of stem 28 is mounted in a spider 27 secured on or in the pipe 25.

During the normal operation of the boiler the valve 16 is held raised by the preponderance of upwardly-acting force applied to it by the boiler pressure, and valve 26 is held open by the springs 31. Water circulates constantly through the external connections and past the two valves, keeping the entire system free from sediment and scale. If a rupture occurs in these external connections, the unbalancing of pressure on the outside of valves 16 and 26, due to escape of pressure through the rupture to the atmosphere, and to the pressure remaining in the boiler, causes these valves to seat with great force. The resistance of springs 31 is overcome, as is also the resistance of buffer spring 23, if employed. These two valves remain closed; isolating the circulaopens. The entire action of the system is thus automatic.

The type of valve employed, namely, a slide valve operatingto close ports, and the fact that the valve when closed is actuated by the boiler pressure, will insure that any deposit or scale which may be formed will not be able to prevent complete and effective closure, as would occur where a valve is used which closes by pressing upon a seat. Any scale getting between the edges of the valve and port will be sheared oil? by the boiler pressure acting upon the head of the valve.

What I claim as my invention is:

In combination with a boiler shell, an external circulating pipe connected at its upper and lower ends to the interior of said shell below the normal water level therein, and normally in free communication therewith and subject to pressures therein, a valve within the boiler controlling communication with the upper end of the circulating pipe, and normally open, a second valve within the boiler controlling communication with the lower end of the circulating pipe, and a valve rod connected to said second valve and extending through the boiler shell, the upper and lower surfaces of said second valve being normally exposed to and acted upon by forces originating in the downward and upward components, respectively, of the pressure in the boiler, whereby said second valve is normally held raised by an upwardly acting force which is the resultant of the said downwardly acting force on the area of the upper surface of the valve,-less the area of the valve rod, and the said upwardly acting force on the whole area of the lower surface of the valve, and said second valve being otherwise unsupported.

Signed at Seattle, King County, Washington, this 13th day of July, 1926.

LOUIS-D. ROWLAND.

tion and blow-off system from the boiler,

until the boiler pressure drops substantially to atmospheric pressure. While closed repairs can be effected, temporarily or permanently. After completion of the repairs one of the valves is manually opened, placing the circulation system in communication with the interior of the boiler, whereupon the other v valve opens, and circulation is resumed.

When it is desired to blow-oil the boiler,

' this may be done by restraining the downward movement of the cutoff piston through securing the rod 37, or in any other way. Opening the blow-off valve 13 causes the valve 26 to close, insuring that sediment collected on the bottom of the boiler is blown out. Upon closing the blow-off valve 13, the piston 16having been held open, the circulating system thus remains in communication with the interior of the boiler, and the valve 26 promptly re-

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