US1349554A - Superheater - Google Patents

Description

UNITED STATES PATENT OFFICE.

JOHN P. BADENHAUSEN, F PHILADELPHIA, PENNSYLVANIA.

'l scrum-marne.

Specication of Letters Patent.

Application liled May 27,' 1916. Serial No. 100,286.

T0 all whom it may concern: d

Be it known that I, JoHN P.'BADEN HAUsEN, a citizen of the United States, residing at Philadelphia, in the county of 5 Philadelphia and State of Pennsylvania,

have invented new and useful Improvements in Superheaters, of which the following is a specification.

This invention relates to superheatersand,

` with reference to the more` specific features thereof, has particular reference to the type of superheaters used n .conjunction with steam boilers. l

The principal .object of the invention is to provide a superheater wherein the circulation of steam therethrough will be free and unrestricted, in order to `eliminate the great loss of pressure caused by the frictional resistance to the passage 'of steam, as is the case inthe forms ofy superheaters hitherto in genera use. l

Another object is to obviate the flash action of steam in a superheater, and thus to. avoid the decomposition of the steam into free oxygen and hydrogen, and to insure an absolutely positive flow of steam through the superheater so that no parts of it will be shortlcircuited, and toso arran e the parts of the superheater so that both t e inlet and 80 outlet connections thereof will be disposed 'will be exemplified in the construction herein described and the scope of the application of which will be indicated in the following claims. v

In the accompanying drawing, wherein is shown one of the various posslble embodiments of the invention,

Figure 1 is a side elevation of the superheater comprising the present inventlon, illustrating diagrammatically the applica- :'50v tion of the same to a boiler,

Fig. 2 is a front elevation of the-supen heater, disclosing the means for supporting the same within a boiler,

Fig. Sissa diagrammatic view disclosing' generally the construction or principle of super-heaters hitherto `in general use,'and

Fig. 4 is a detail of Fi 3. Similar characters ofl re erence denote oor- Patented Aug. 17, 1920.

responding parts throughout all the views of I the drawmg.

In order that the aims vention will bel clearly understood, a brief ""'u ofthe present ini synopsis of the construction and principle of operation of superheaters, which have been hitherto in general use, will be given,

the general design thereof having been con-` ventionally shown in Fi s. 3 and 4.

As disclosed, the old ormof superheater consists of headers l and 2, connected by means of substantially U-shaped tubes 3;

steam flows into one header by means of a` supply pipe 4 and away from the other header by means of an outlet pipe 5. The pipes 4 and 5 are usually placed at the opposite ends of the headers, with, the idea of compelling the steam to liow more evenly through the tubes 3. It is to be particu-v larly noted that the flow through the tubes 2 is in parallel, that is, if there are twelve tubes used, the steam is supposed to divide itself into twelve equal parts, each of the latter being adapted to flow through one of the tubes 3, but this cannot take place unless each of these tubes have exactly the same resistance to the fiow of steam as the other, and a construction of the apparatus l with this equality` of resistance in the tubes is not commercially possible, hence to cause an equal quantity of steam to flow through each tube is not commercially practical. Moreover, as the boiler to which the superheater Y is attached may, as occasions demand, be

operated through a wide range of loads,

the quantity of 'steam passing into and.

through the superheater will vary in the same way, hence the amount of steam passing through each tubewill vary to the same degree at least, thus the velocity of the steam so passingwill varyin a similar manner. But, as known to all'skilled inthe art, the rate voftransmission of the heat from the metal of the tubes to the steam depends largely upon the velocity of thev steam, hence under the above conditions the rate of heat transmission must vary unless the heat absorbed y the tubes from the hot gases be transmitted at once to the steam flowing within llthe tubes then the tem.-

perature of the tube* itself will rise, and Y unless such rise be checked the tubes will be .overheated and destroyed, this event happens with such regularity and frequency as eatly also. But

to prove the insuiiiciency and imperfections of the type of superheater above described.

It is known to all who are experienced in boiler matters that when the boiler feed valve, (not shown), is opened and feed water is entering the boiler, the rate of steam production falls rapidly because the heat usually available for absorption by the boiler is mostly used to raise the temperature of .the fresh feed water up to the temperature of ebullition, hence but little heat is available for steam generating, thus the steam output of the boiler decreases, thereby causing the velocity of flow through the tubes to decrease, by reason of which the tube overheats. Due to such overheating a most pernicious result occurs, that is, the disassociation of the steam into free oxygen and hydrogen. That such action does occur is shown by the table based on the experiments of Doctor Bunte, and found on page 68 et seg. of A Treatise on Producer -Gas and Gas Producers, by Samuel S. Wyer, 1906. The hydrogen thus, produced quickly destroys the'engine lubricants, and the oxygen attacks the metal of the pipes and fittings, and acts with particular intensity on cast iron, which explains why cast iron fittings are, by many, considered unsafe when superheated steam is employed.

4It is also well known that when the rate of superheating per foot of tube space traveled over is very high, the steam in contact with the superheating surface receives heat faster than the steam farther away from the superheating surface and nearer the center of the tube, hence superheats, increases 'its volume faster and also increases its velocity, so that the steam near the center of a tube travels slower than that farther from the tubes, and that because of this any free water brought into the superheater with the steam is pushed into the center of the tubes where the steam travel is slowest, and thus passes along and through the superheater in a thin string or pencil which is not evaporated at all. -This explains why many superheaters carry over moisture into the steam mains, and why certain superheater manufacturers refuse to guarantee the action of their apparatus if the steam as delivered to them contains over one per cent. of moisture. l

To obviate these troubles, I abandon the entire scheme or principle of passing the steam through a multitude of tubes in parallel between headers and so proportion that through the steam pipes.

the cross section of these tubes aggregates a much larger vcross section than that of the steam pipe, so that the steam velocity through the tubes is much less' than that The present invention comprehends passing the steam through tubesl whose total cross sectional area is at least equal to that of the steam pipe when properly proportioned, so that lthe steam velocity cannot drop below that 1n the steam pipe and the superheat is gained by increasing the length of the steam travel, by connecting sets of tubes in series and using a suiiicient number of sets to compel the steam to travel any distance necessary to develop the superheat needed in any case.

ln this manner, the steam is caused to absorb the heat gradually in its travel, thus all flash action and disassociation of the steam into free oxygen and hydrogen are obviated. Further, by doing away with the flash action and sudden great increase in the velocity of steam in contact with the tube walls I overcome the action of concentrating the entrained water into a pencil at the center of the tube; by causing the steam to flow into the headers successively during its travel, the steam will be thoroughly mixed or intermingled so if any water is contained in it this water during the passage through the next set of tubes is brought into contact with the tube surface, hence is evaporated, thus in the present design of superheater all the entrained water is evaporated and only superheated steam is delivered at the superheater outlet.

As shown in Figs. 1 and 2, steam from the boiler comes through the pipe S to the header 10, from which it fiows through the tubes 11 to the header 12, then by way of the tubes 13 to the header 111, and from the opposite extremity of the header 141 to the header 15 by way of tubes 16 and is discharged from the header 15 into an outlet pipe 17. While there has been illustrated three sets of tubes or the like 11, 13 and 16, use may be made of any number, greater or less` according to the degree of superheat wanted. Each set of tubes 11, 13 and 16 is so arranged that the total cross sectional area of the tube bores is approximately equal to the cross sectional area of the steam pipe when properly proportioned.

t will be noticed that the header 15 is so set that the end opposite that at which the tubes enter is on the same side of the superheater as the inlet pipe 8, hence the entrance and the exit of the superheater comprising the present invention is on the same side of the boiler, thus eliminating the necessity of carrying any piping through the party wall 18 of a boiler setting.

Referring more particularly to the precise details of construction of my superheater, the same is illustrated as being associated with the water drum 19 of a boiler 20, of the type fully set forth in my copendine patent application bearing Serial No. 81917, filed i arch 3, 1916. The numerals 21 designate water tubes which extend to other drums of the boiler 20 not shown'fand between which the superheater is preferably located, th'ough it is obvious that the superheater 22 could be located, and operate with equal eiliciency, in other locations, and that this ap*V plication centers on the construction of the superheater 22 without referring particularly to its exact location. The superheater 22 may be connected with the boiler` 20 by means of a hanger 23 connected with the superheater and with the framework 24 of said boiler. rIlle header 12 has the tube sets 11 and 13 communicating therewith adjacent the lower extremities of said tube sets, while the upper extremities of the latter terminate in the headers 11 and 14. The upper extremities of the tube sets 16 are connected with the header 14 and at their lower ends with the header 15. The header 15 extends outwardly beyond the boiler walls and terininates in a flange 25 or other suitable connection and a similar flange 26 or the like is used at the beginning of the header 10. ill partition 27 separates the headers 10 and 14 so that the steam entering the header 10 will necessarily have to pass through the 'tube banks 11, to the header 12 and tubes 13 before entering the header 14. The headers 10 and 14 may be formed of ytwo independent sections, if so desired, h owever, it has been found preferable to form the same `from one sectionand place the partition 27 therein so as to form the compartments 10 and 14. It will be observed that the steam when circulating through the superheater is forced to travel in series to the various headers and tube banks comprising the same, and that the Asteam will enter and leave the superheater on the same side of the boiler. The headers 12 and 15 are preferably secured together by means of straps 28, which are welded to said headers so that they may be securely connected. The sul perheater is retained in this position within 'the boiler by means of the hanger 23 which suspends the headers 10 and 14 from the framework 24 of the boiler and the lower header 15 is supported by means of a bearing 29 positioned upon the lower bar 30 of the framework 4, thus it will be seen that the superheater issupported within the boiler by means of bearings or hangers secured to the framework thereof and is independent, with reference to support, of thev boiler walls. pansion the various tube sets of the superheater are approximately V-shape in elevation, this construction also permits the superheater to be readily positioned between the tube banks 21 of the boiler.

From the foregoingr description it will be observed that the objects of the present invention have been achieved and that all the advantageous features above mentioned are, among others, present. Summarizing the invention it will be noted that the superheater comprising the present invention per- In order to provide for free ex mits the steam flow therethrough to be absolutely positive and that no part of the superheating surface can be short circuited. Moreover, a design is produced in which the rate of superheating per foot of travel of the steam is constant for/ any given steam velocity within the tubes and gas tempera'- ture without the tubes, so that the degree of superheat obtained depends upon the length of tubing to be traversed by the steam. The superheater also obviates all flash action in the superheater tubes, thus preventing formation of free oxygen and hydrogen, and also preventing the aggregation of entrained water in the center of said tubes and its' consequent flow through the superheater. It will be noted that the inlet and outlet pipes of the superheater are located on the same side of the boiler, so that I do away with the necessity of carrying steam mains through the party wall of the boiler setting.

The tubes of the superheater will be attachedto the headers by welding the tube ends directly tothe header and not by expanding them into the tube holes as is usually done, thus'l eliminating all loose joints liable to breakage.

Having described my invention, what is claimed as new and patentable is In a superheater for steam boilers, the combination of a pair of vertically spaced relatively long headers of substantially equal and uniform diameters extending transversely of the boiler space, said headers being open at one end thereof and closed at the other end thereof, one of said headers being provided with a pair of alined chambers and the other of said headers having a single chamber, a third relatively short header of substantially the same diameter as said'long headers and independent of said long headers and located in parallel relation to said last mentioned long header and secured thereto, said third header being closed at both ends and having a single chamber, a plurality of laterally extending V-shaped tubes connecting the chamber of said third header with the chambers of said first header, and a plurality of laterally eX- tending-'V-,shaped tubes connecting the first and Vsecond mentioned headers near the closed4 ends thereof,the open ends of said headers being on thesame side of the boiler, said V-sha'pe'd tubes being located in the first passy of the boiler whereby the hot gases may successively Icontact with the lower and upper portions thereof and whereby the steam Howing therethrough. has a travel transverselyof the boiler.

In testimony whereof I affix my signature in presence of a witness.

\ JOHN P. BADENHAUSEN.

Witness: AMY B. HORN.

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