US2024574A - Automatic drain valve - Google Patents

Description

D. W, 1935. c. w. GORDON 2,924,574

AUTOMATIC DRAIN V VALVE Filed Jan. 15, 1934 INVENTOR CHARLES M gazaa/ F/J 57 BY I QKZKM ATTORNEY Patented Dec. 17, 1935 PATENT OFFICE AUTOMATIC DRAIN VALVE Charles W. Gordon, Munster, Ind., assignor to The 'Superheater Company, New York, N. Y.

Application January 15, 1934, Serial No. 706,614

8 Claims.

The present invention relates to superheaters and aims to provide a novel and efficient means for protecting superheaters from over-heating.

Many superheater installations at present are designed for final steam temperatures approaching the safe limit of the metal of the tubes in the superheater so that variations in load and firing conditions not infrequently cause the metal of such tubes to become overheated. Frequently,

the worst conditions to which the tubes of a superheater are exposed occur in firing up the boiler, there being then no useful steam flow thru the superheater acting to cool the tubes. An insuflicient flow of useful cooling steam thru the superheater may occur also at other times especially when a large load is suddenly thrown off the boiler. In accordance with my invention, means are provided whereby steam is permitted to escape through the superheater or superheat- 20 ers whenever the amount of steam going to the intended steam consumer or consumers attached to the superheater or superheaters is below the amount needed at the time to prevent overheating of the tubes of the superheater.

25 The novel features of my invention are pointed out in the appended claims. In order, however, that the invention, together with its objects and advantages, may be more fully and readily understood, I will now describe in detail and in con- 30 nection with the accompanying drawing two superheater installations which are exemplifications of the invention, selected from a number of possible embodiments thereof. In the drawing,

Fig. 1 is a vertical sectional view, diagrammatic 35 in character, of a superheater boiler having my invention applied thereto. 7

Fig. 2 is a detail view, on an enlarged scale, of a portion of the apparatus illustrated diagrammatically in Fig. 1, parts being shown in section 40 and parts being broken away for purposes of i1- lustration. Q

Fig. 3 is a diagrammatic view similar in character to Fig. 1 but illustrating a different species of the invention. g

45 Fig. 4 is a view similar to Fig. 1 but illustrating a third species of the invention.

The apparatus illustrated in Figs. 1 and 2 comprises a boiler IQ of known type having a superheater 12 connected therewith, the heating units 50 I l of said superheater lying in the path of the heating gases flowing through boiler l0. Su-

perheater l2 has a header It for saturated steam and a header l8' for superheated steam, header l6 being connected to boiler [0 by an inlet con- 55 duit 20. Steam from header it flows through the units I4 into header l8 and the superheated steam is conducted from header l8 to the point of use through an outlet pipe 22. Frequently boilers are installed in batteries and I have shown outlet pipe 22 connected to a steam main 26 and 5 therefore have provided a non-return check valve 26 in the pipe 22.

Steam flowing through the tubes it normally cools them to prevent their overheating, it being assumed that main 24 delivers to one or more 0 steam consumers wln'ch normally place sufiicient load on boiler H) for this purpose. Whenever, either during starting up periods or during ordinary running periods, conditions are such that overheating may be anticipated, the units M are protected in accordance, with my invention by blowing off steam from header l8 either to waste or to some point other than the normal steam users connected to main z l. Themeans illustrated for this purpose comprises a blow-off line having a pipe 28 connected to the header i8 and a pipe 30 connected to discharge the steam. Intermediate pipes 28 and 32 is a balanced valve 32 shown as immediately adjacent the pipe 39. Valve 32 is biased to the open position by a spring 3% arranged to act on the stem 35 of such valve. Valve 32 is shown as standing open. Intermediate the valve 32 and the pipe 28, the blow-off line branches, one branch 36 containing an adjustable restriction 38 therein and the other branch to containing a second balanced valve 42 which is biased to the closed position by a spring M acting on the stem 85 of valve 42. The two branches 36 and #20 extend between the points 46 and 48, point t3 being between valve 32 and valve 42 so that a small amount of steam can flow through branch 36 and valve 32 and so be discharged through pipe 30 without reference to the position of valve 42.

Spring 34 holds valve 32 open, as shown, to permit such escape of steam until overpowered by means responsive to the flow of steam thru the units I 4. Such means comprises a diaphragm 5% the lower face of which is connected by pipe 52 to the inlet or saturated header it of superheater I2. Thepressure in the header I 6 thus tends to close valve 32 against spring 35. The upper face of diaphragm is, however, connected to the pipe 28 or to header l8 by a pipe 54,

the pressure in header l8 therefore tending to 50 hold the valve 32 open. When'there is a certain flow thru units l4, a suflicient pressure dinerence develops between headers l6 and i8 to overcome the spring 34 and to close valve 32, header I8 having, thelower pressure during flow thru 55 ratus are so designed that valve 32 stands open unless suflicient steam is flowing to the load thru the superheater to protect it against being overheated by the furnace gases.

In line 36 and preferably at the point 46, I place a thermostat 56 containing a volatile fluid the pressure of which is conducted by a pipe 58 to a chamber beneath the diaphragm 60 which is so associated with the stem of valve 42 that pressure on the under side of diaphragm 60 tends to open such valve. When the temperature of steam in the branch 36 coming from the header I8 rises to a certain point, sufficient pressure is generated in the thermostat 56 to raise the valve 42 and permit a considerable flow of steam through the discharge pipe 30 of the blow-oil line. The amount of steam thus blown off is limited by the valve 32 to that needed to protect the units I4 against overheating, an excess amount over that needed for such purpose being prevented by the fact that the'flow itself creates a pressure difference between headers I6 and I8 which acts through pipes 52 and 54 on the diaphragm in the direction tending to close the valve 32.

It will be seen that in the operation of the apparatus shown in Figs. 1 and 2 the valve 42 will be opened, if valve 32 is open, at any time when the temperature of steam in outlet header I8 rises above a predetermined point irrespective of whether this occurs during starting up periods or ordinary running periods of the boiler or superheater. A quantity of steam which may be regulated and. predetermined by valve means 38 in branch 36 flows throughsuch branch and valve 32 so long as valve 32 is open, but such flow is quite small and the steam so escaping through pipe 30 can be utilized in preheating feed water or in other ways so that it is not entirely lost.

; Of course, whenever valve 32 is closed, there is not any-flow in branch 36 and the steam surrounding thermostat 56 cools off permitting valve 42 to close. 7

The arrangement illustrated in Fig. 3 is the same as that of Figs. 1 and 2 except that the boiler IDA has baffling therein and that the thermostat 56A is exposed to the combustion gases of the boiler IOA, instead of to steam from the superheater. I do not limit myself to the use of baffling, however. Whenever the gases are hot enough to endanger the superheater, valve 42 is opened by thermostat 56A. If, at the time, insufficient steam is flowing thru the superheater to protect it, valve 32 then opens and permits sulficient flow for this purpose.

In the drawing, the valve 42, which is biased to the closed position, is placed closer to the header I8 than the valve 32 which is biased to theopen position. However, I do not limit myself to this and in the system illustrated in Fig.3 the relative position of valves 32 and 42 is entirely immaterial.

. The arrangement illustrated in Fig. 4 is the same as that illustrated in Fig.1, except that the thermostat 563, instead of lying in the by-pass or branch 36 is in the header I8 at the junction of pipe 28 with such header but arranged to contact with steam flowing thru the header I8 to the normal steam users on line24 as well as with steam going thru pipe 28 and line 30.

It is permissible as to all forms of the invention illustrated that 'valve 42 shall stand open when thermostats 56, 56A, and 56B have arrived at the temperature desired for theaverage working temperature of the superheated steam. The flow of steamthru the waste pipe 30 is then controlled r the superheater. Valve 32 and associated appaby valve 32. The spring 34 of such valve is set so that it permits valve 32 to close whenever there is sufiicient flow thru the superheater to the nor-' mal steam users to protect it against overheating.

When such useful flow thru the superheater falls off to such a point that it affords insuflicient pro-- tection to the superheater, the spring 34 over-' comes the efiect of diaphragm 50 and opens the valve 32. Such opening, however, due to the nature of springs, is almost exactly proportional to the amount by which such useful steam flow falls below that required to protect the superheater, so that there is no unnecessary draft of steam from the boiler.

While the operationof'apparatuses illustrated will be apparent, to those skilled in the art from the foregoing description for purposes of convenience, I will now give a rsum of the operation of such apparatuses in certain situations occurring occurring commonly in use.

As to all three forms of apparatus illustrated: when the boiler is cold, valve 32 is open and valve 42 is closed.

As to the apparatus of Fig. 1: during starting up, Valve 32 is open and valve 42 is closed at first but will open as soon as the steam temperature reaches a predetermined point and stay open thereafter as long as there is no load on the boiler due to the probable high temperature of steam around the thermostat 56 whenever the boiler is being fired without load. During ordinary running conditions, valve 42 of Fig. 1 will be closed due to the lowertemperature of the steam surrounding thermostat 56, while valve 32 will also be closed, or nearly so. Under emergency conditions, if the engine connected to the boiler of Fig. 1 suddenly drops its load, valve 32 immediately opens while valve 42 opens soon after due to increase in temperature of the steam surrounding thermostat 56. When the boiler of Fig. l is on dead bank, valve 42 is closed and valve 32 is open; when on floating bank, valve 32 closes and valve 42 will remain closed.

As to the apparatus of Fig. 3: during firing up, valve '32 is open and valve 42 is closed at first, out opens when the gases become hot. During normal running conditions, valve 32 of Fig. 3 is closed and valve 42 is open. If the engine connected to the boiler of Fig. 3 suddenly drops its load in an emergency, valve 32 immediately opens while valve 42 is already open, thereby affording immediate protective circulation. When the fire is checked, valve 42 closes, while valve 32 remains open. When the boiler of Fig. 3 is on dead bank, valve 42 is closed and valve 32 is open; on floating bank, valve 32 is closed and valve 42 is open.

As to the apparatus illustrated in Fig. 4: during the starting up period, valve 42 is closed at first and valve 32 is open. Valve 42 also opens when the steam becomes hot. When the boiler of Fig. 4 is put on the line, valve 32 closes due to the difference in pressure with a normal flow of steam, while valve 42 remains open. If the engine connected to the boiler of Fig. 4 drops its load in an emergency, valve 32 immediately opens, while valve 42' is already open. A fully protective circulation is at once established and is maintained until the fire is checked. When the fire has been checked, valve, 42 closes whilevalve 32 remains open. If the boiler of Fig. 4 is put on dead bank, valve 42 closes while valve 32 remains open. If it is put on floating bank, however, valve 32 closes while valve 42 will remain open. 7

Comparing the apparatus of Fig. lwith that of Fig. 4, the two systems function in much the same manner, but it is preferred to design the thermostat for the system of Fig. 4 so that it will open valve 42 when the boiler is on the line, resulting in that the valve 42 is open during the first part of any emergency period. This is desirable rather than otherwise, as it makes the system more sensitive and quicker action is therefore obtained when needed. After the fire is quenched, the action of valve 42 is the same in both cases. During the bank period, the action of both types is the same.

Comparing the apparatus of Fig. 3, in which the thermostat is in the gas space, with the systems of Figs. 1 and 4, the action of the system of Fig. 3 differs from those of the other two figures mentioned in that the by-pass is eliminated and therefore no steam is wasted in the banking condition or during the starting up period, when the gases are too cold to damage the superheater.

While I have described and illustrated several arrangements which fall within my invention, I do not limit myself to such arrangements or to particular details of the disclosure, it being understood that the appended claims are to be construed in their broad sense and without importation of unnecessary limitations from other parts of the disclosure In particular I do not limit myself in all cases to passing the steam from the leak thru an automatic valve as it may go direct to the atmosphere.

What I claim is:

1. The combination of a heater having an outlet pipe for delivering fluid to an intended consumer thereof, a blow-off line connected to receive fluid from the outlet side of said heater, a valve in said line biased to closed position, automatic means for opening said valve to permit fluid to flow through said heater whenever the fluid temperature in the heater rises to a certain point; and automatic valve means to limit the flow through the'valve biased to closed position to prevent waste of steam.

2. The combination of a heater having an outlet pipe for delivering fluid to an intended consumer thereof, a blow-01f line connected to receive fluid from the outlet side of said heater, a valve in said line biased to closed position, means providing a fluid leak from the outlet side of said heater, a thermostat arranged to respond to the temperature of the fluid flow caused by said leak, means controlled by said thermostat for opening said valve at a prescribed upper temperature limit, and a second valve in series with the said first mentioned valve, such second valve being biased to the closed position, and automatic means for controlling the position of said second valve to prevent wasting steam.

3. The combination with a heater having an outlet and an inlet of a blow-off line connected to said outlet and containing two automatic valves in series, means whereby one of said valves is biased to the open position, means whereby the other of said valves is biased to the closed position, means including a thermostat for opening said other valve at a prescribed upper limit of steam temperature, and means for closing said one valve whenever there is a predetermined steam flow thru the heater.

4. The combination as set forth in claim 3 and in which the means for opening the valve which is biased to the closed position includes a by-pass around such valve in which the thermostat is located.

5. The combination with a superheater having an outlet and an inlet of a bloW-ofi line connected to said outlet and containing two automatic valves in series, means whereby the one of said valves farther from said outlet is biased to the open position, means whereby the one of said valves nearer said outlet is biased to the closed position, means including a thermostat for opening said valve nearer the outlet to protect the superheater from excessive temperature, and means for closing said farther valve whenever there is a predetermined steam flow thru the superheater.

6. The combination with a superheater having an outlet and an inlet of a blow-off line connected to said outlet and containing two automatic valves in series, a spring arranged to bias one of said valves to the open position, means arranged to bias the other of said valves to closed position, means including a thermostat for opening said other valve to protect the superheater from excessive temperature, and a diaphragm subject to pressures from said inlet and outlet on opposite sides thereof for closing said one valve whenever there is a predetermined steam flow thru the superheater.

7. The combination with a superheater having an outlet and an inlet of a blow-01f line connected to said outlet and containing two automatic valves in series, means whereby one of said valves is biased to the open position, means whereby the other of said valves is biased to the closed position, means for closing said first valve whenever there is a predetermined steam flow thru the superheater, and means for opening said other valve to protect the superheater from excessive temperature including a thermostat located in said outlet at the point of connection thereto of said blow-oil line and so arranged as to be contacted by steam in said outlet flowing either to said blow-01f line or to the normal consumers of steam leaving the superheater.

8. The combination with a superheater having an outlet and an inlet of a blow-off line connected to said outlet and containing two automatic valves in series, means whereby one of said valves is biased to the open position, means whereby the other of said valves is biased to the closed position, means for closing said first valve whenever there is a predetermined steam flow through the superheater, a boiler in which said superheater is located, and means for opening said other valve to protect the superheater from excessive temperature, and including a thermostat located in the path of gases for heating said boiler.

CHARLES W. GORDON.

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