US2019606A - Superheater recirculator - Google Patents

Description

Nov. 5, 1935. F. HAAK ET AL SUPERHEATER RECIRCULATOR 2 Sheets-Sheet 1 Filed Feb. 28, 1954 INVENTOR 5 FWM/K 14/. J/W/T/f. BY FRE R/(K H00 K.

ATTORNEY Patented Nov. 5, 1935 UlTED STATES SUPERHEATER RECIRCULATOR Application February 28, 1934, Serial No. 713,326

10 Claims.

Our invention relates: to the protection of superheaters from overheating and aims to provide a method whereby such protection may be afiorded in a simple and economical manner, as well as to provide an arrangement adapted to operate in accordance withsuch method.

Large numbers of fire tube boilers are in use which have superheater units arranged in enlarged fire tubes or flues and extending from the smoke box end of the boiler close to the fire box or combustion chamber. Such an arrangement is most commonly used in locomotives, but is well adapted to. any horizontal or vertical fire tube boiler. Difliculty has been experienced in protecting the superheater units in such'installations from overheating at times when little or no steam is passing through the units.

A common source of deterioration in superheaters is that there is ordinarily no flow through the 'units during the period the boiler is beingfired up. The draft and the gas temperatures during such period'may, however, be quite high, especially in locomotives, resulting in overheating the units.

other boiler, our arrangement provides a means of largely avoiding the deterioration due to such conditions, and it is an object of our invention to utilize our arrangement for protecting superheater units during firing up conditions.

Also, asource of difiiculty in the operation of locomotive and other superheaters has been also that the interior of the units; may become incrusted by solids carried into them in solution or suspension in water in the steam. The arrangement suitable for circulating steam thru the units to prevent their overheating is suitable also for flowing cleaning fluid such as hot water or weak acid thru the units to clean them when the boiler is not in operation. It is an object of our invention to so utilize our arrangement for cleaning the interior surfaces of superheater units. It has been'proposed to avoid overheating by pumping steam through superheater units whenever neces- M sary; We therefore do not claim this idea broad- 1y, but our invention includes treating superheater units by passing fiuid through certain of the units of a superheater in one direction and returning it to the boiler through the remainder of l such-units in the opposite direction. We are thereby enabled to increase the velocity of steam in the units sufficiently to obtain adequate protection from overheating when using a smaller quantity of circulatingsteam and to readily and effectively empty cleaning or like fluid. Our in- In connection with the steam from an-' vention includes further arrangements whereby such method may be carried out.

In order that our invention, together with its objects and advantages, may be fully and readily understood, we will now describe in detail, a su- 5"- perheater installation of the locomotive boiler type which is adapted to act in accordance with our novel invention, and which embodies our novel arrangement. In the drawings,

Fig. 1 is a vertical sectional view through the 10 The apparatus illustrated in the drawings com- 20 prises a locomotive boiler it within the cylindrical shell of which is a dry pipe l2 leading from the' upper end of a'steam dome it which projects upwardly somewhat from the contour of the shell. The dry pipe l2 delivers into an inlet header 116 25' located in the smoke box E8 in front of the for- Ward flue sheet of boiler Ill. The header l6 has fixed thereto hollow fingers 20, 20 into which the steam flows" from the inlet header proper and from which steam flows into the inlet ends 22 of 30 a group of superheater units 24 arranged in the enlarged smoke flues of boiler Ill. The outlet ends of units 2 3' deliver the steam to hollow fingers 2t, 26 the interiors of which connect with an outlet header 28 from which steam may be3 taken by one or more throttle valves 30 into a passage 32 connecting with the steam pipes 34, 34- of the ordinary locomotive engine. The arrange ment heretofore described is Well known and forms no part of our present invention except in 40 so far as our invention is necessarily applied to analogous structures.

In accordance with our invention, the header structures, including the fingers 2t and 26, when such are used, are divided by central partition means 36 (Fig. 2) the units 24 thereby are divided into two sets, one connected to the header on each side of such partition 35. The partition 36, it will be understood, does not extend through the outlet' passage 32 which is on the outlet side of the 5 valve or valves 30 so that it has no elfect on the flow of steam through the units 24 so long as the valve or valves 36 are open enough to provide a substantial flow of steam through pipes 34. When, however, sufiicient' steam is flowing thru the units 24 as to maintain them at a non-damaging temperature, the partition means 36 and the associated features about to be described remain idle. Whenever the steam flow to passage 32, however, is substantially or wholly shut off it becomes very desirable to provide other means whereby there may be a flow of steam through the units 24. For this purpose, we provide a pump 38 adapted to pump steam, and connected to the outlet header chamber 28 on both sides of the partition 36, so as to pump steam from one side of such partition to the other. Connecting pipes 48, 48 are illustrated for this purpose. Pump 38 is connected to be driven by a small steam turbine 42, steam for which is taken from boiler I0 through a pipe 44. Steam exhausted by the turbine 42 may be discharged through pipe 45 to any convenient point. Preferably the operation of pump 38 and turbine 42 is controlled automatically by the pressure in the steam pipe 34. For this purpose, we have illustrated an automatic valve having a casing 46 within which is a valve member 48 adapted to cooperate with a seat 50 within the casing 46 to cut off the-flow of steam therethrough and therefore to the turbine 42. Valve 48 is connected to the piston 52 withinv from the arrangement heretofore described that whenever pump 38 is in operation, steam is taken from the outlet header chamber 28 on one side of the dividing means 36 and put back into such header chamber on the other side of such means. Such flow of steam through the units 24 is indicated by the arrows leading from one side of header chamber 28 to the other side (Fig. 2). However, such a flow of steam from one half of chamber 28 to the other requires that the steam flow through one half of the inlet header and the units connected thereto to one-half of the outlet header chamber 28 and flow from the other half of such outlet chamber through the remaining units 24 back to the other half of the inlet header and thence to the boiler, thus providing a cooling circulation of steam through all the superheater units. It will be clear, however, from Fig. 2 that the partition 38 is not needed in the outlet header unless, as in the specific arrangement illustrated, the pump for circulating steam, pump 38, is connected to the outlet header. We do not limit ourselves,,therefore, in all cases to using a partition in the outlet header.

In the ordinary locomotive, the steam is conducted to the inlet header such as l 6, or the like, by a dry pipe I2 which takes in steam from within dome l4. Whenever a dry pipe is used, whether one of the internal type or one of the external type, we extend the dividing means 36 in the form of a central web 36a through horizontal length of pipe l2. Further, in order to prevent direct recirculation of steam thru pipe I 2 and the superheater units; that is the short circuiting of superheated steam'in dome I 4 by the drawing into one half of the dry pipe steam which has just been discharged from the other side, the portion of the dry pipe which extends into the dome I4 is bifurcated to form two spaced sections l2a, I |2a having a vertical partition 50 therebetween,

such partition extending on a diameter of dome I4 entirely across the interior of such dome and from the top thereof to below the top level of the shell of boiler l8. However, we do not limit ourselves to the use of a dry pipe. 5

In starting up a locomotive or other boilers, the superheater units are often subjected to gases of. quite high temperature before there is enough steam in the boiler to operate a circulating pump. In accordance with our invention, steam from an outside boiler is used to operate the pump and to supply fluid to be circulated thereby. In the arrangement illustrated, a valved pipe 60 is run out from the pipe 45 by which steam normally enters the turbine 42 for driving circulating pump 38 and extended thru the shell of the smoke-box so that it can be connected to the round-house or like boiler. Also a valved connection 62 is extended from inlet header it thru the wall of the smoke box so that steam from the round house or like boiler can be supplied for circulation through the units of the superheater by pump 38.

A common cause of the failure of superheater units "is the overheating of the metal due to internal scale. We overcome this difiiculty by cleaning the units when the boiler is out of service, by removing the ordinary cover plate on the steam dome 14 (Fig. 4) the upper bifurcated ends I 2a of the dry pipe are exposed rendering it easy to then connect tubes 18 and 72 to the ends [2a by 30 caps 74, or other suitable means, so that cleaning fluid such as weak acid or hot water may be forced through the units. In the arrangement shown, tank 16 is a reservoir for cleaning fluid which is drawn from such tank thru pipe 10 by pump 18 and forced thru pipe 10 into one end l2a. After passing thru the units 24, first in one direction and then in the other, the cleaning fluid is delivered to the tank 16 again thru pipe 12.

' It is evident that all the features illustrated in the drawings and described hereinabove are not necessary to our invention. Therefore we Wish the following claims to be construed broadly and not to be limited to features of the disclosure not expressed therein.

What we claim is:

1. The combination in a superheater boiler of an inlet header, an outlet header, means dividing said headers into two portions and preventing passage of steam longitudinally between the 50 header portions on opposite sides thereof, superheater units connected between said headers and some on one side and some on the other of said means, means whereby fluid may be passed from the boiler thru those of said units on one side of 5 said dividing means and then thru the rest of said units from the outlet to the inlet header and back to the boiler.

2. The combination of a boiler, a group of superheater units therefor, inlet and outlet headers for such units, means dividing said headers into halves, and means whereby steam may pass from the boiler through those of said units connected between one of said headers and the other on one side of said dividing means and then pass back into the said boiler through the units connected between said headers on the other side of said dividing means.

3. The combination of a boiler, a group of superheater units therefor, inlet and outlet headers for said units, a dry pipe extending through a portion of said boiler and connected to said inlet header, means dividing both said dry pipe and said headers into halves, and means for moving steam from the boiler through the portion of said 75 dry pipe on one side of said dividing means and through those of said units connected between one of said headers and the other on the same side of said dividing means and for moving such steam back into the boiler through the units connected between said headers on the other side of said dividing means then through the other half of said dry pipe.

4. The combination as set forth in claim 1 and in which the means by which the steam may be passed from and to the boiler comprises a pump for steam connected to the outlet header on opposite sides of the dividing means.

5. The combination as set forth in claim 2 and in which the means for moving the steam from and to the boiler comprises a pump for steam connected to the outlet header on opposite sides of the dividing means.

6. A method for preventing overheating of a group of superheater units comprising flowing steam from the boiler through a portion of said units in a direction away from the: boiler and then flowing such steam through the remainder of such units back to the boiler.

'7. The combination as set forth in claim 2 together with bifurcated extensions for the dry pipe, a steam dome intowhich said extensions project, and a partition in said dome intermediate said extensions.

8. The method of protecting the units of a superheater of a superheater boiler during firing up periods comprising flowing steam not generated in said boiler thru part of said units in one direction and thru the remainder of said units in the opposite direction to cool them.

9. The method as stated in claim 8 and in which the steam which has passed thru the units is delivered to the interior of the boiler being fired up.

10. The method of cleaning the units of a superheater of a superheater boiler comprising flowing a cleaning fluid thru part of said units in one direction and thru the remainder of said units in the opposite direction.

FREDERICK HAAK. FRANK W. SMITH.

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