US2293833A - Steam generator - Google Patents

Description

Aug. 25, 1942. M. H. KUHNER ET AL STEAM GENERATOR Filed July 14, 1938 s Sheets-Sheet "1 MAX H. KUHNEI? GUSTAV A. REHM an W g- 1942- M. H. KU'HNER ETAL' 2,293,833

STEAM GENERATOR Q Filed July 14, 19:58 3 Sheets-Sheet 2' MA x H. KUHNEE GUSTAV A. REHM annua Aug. 25, 1942. M. H. KUHNER ET AL STEAM GENERATOR Filed July 14, 1938 3 Sheets-Sheet 3 OO0OOOOOODO OOOOOOOOOOOOOOOOOOOOO OODOOOOOOOOOOOOOOOOOO 000000000000000000000 000000000000000000000 000000000000000000000 000000000000000000000 000000000000000000000 OOOOOOOOOOOfi/OOOOOOOO 2 grvuc vvkvp H. K UHNER GUSTA v A. REE/M Patented Aug. 25, 1942 STEAM GENERATOR Max H. Kuhner and Gustav A. Rehm, Worcester, Mass., assignors to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Application July 14, 1938, Serial No. 219,214

8 Claims.

This invention relates to steam generators, and more particularly to steam generators of the water tube type having water cooled walls at the sides of the combustion chamber.

It is one object of the invention to provide a water tube steam generator capable of producing steam at rates which are high in comparison with the floor space required for the installation.

It is a further object of the invention to provide a steam generator particularly adapted for operation with fuels such as oil, gas and pulverized coal, which are burned while in suspension in the combustion chamber.

It is a further object of the invention to provide a steam generator having a simple and efiective means for supplying water to the lower ends of the water wall tubes.

It is a further object of the invention to provide a steam generator which will be free from difliculties caused by priming and foaming.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawings illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is a longitudinal section through a steam generator, the section being taken on the line l-l of Fig. 3;

Fig. 2 is a, section on the line 2+2 of Fig. 1;

Fig. 3 is a section on the line 33 of Fig. 1; and

Fig. 4 is a fragmentary section on the line 4-4 of Fig. 1.

The embodiment illustrated comprises an upper transverse steam-and-water drum and a lower transverse Water drum therebeneath, these drums being connected by a bank of upright water tubes I2 and by a second bank of upright water tubes l4 located in front of the tubes l2 and somewhat larger in diameter than the tubes l2. The lower drum II is supported on a saddle I5, and the upper drum I0 is supported by the Water tubes. A wall I 6 is provided in the rear of the tube bank l2, and two walls extend forwardly from the rear wall I6 on opposite sides of the water tubes to a transverse vertical plane located a substantial distance in front of the tube bank I4. A bridge wall I9 is provided in front of and beneath the water drum H, and a front wall 20 is provided a substantial distance in front of the side walls IT. The walls l6, l1, l9, and 20 are preferably formed of a self-supporting type of refractory masonry.

Near the top of the front wall 20 there is provided a transverse header 22 which is connected to the steam-and-water drum It) by means of two rows of water tubes 23, the upper row of tubes serving to support a roof 24 of refractory material. A bank of water tubes 25 connects the lower water drum II with the header 22, these tubes being generally L-shaped, with upright lower portions located in front of the tubes l4, and with substantially horizontal upper portions which preferably slope slightly upwardly to the header. There are three rows of these tubes 25, the rows being comparatively closely spaced where the tubes are upright and comparatively widely spaced where the tubes are substantially horizontal. The tubes 25 in the front row are spaced apart more widely than the others, to form a slag screen. A superheater 26 is mounted above the upper sloping portions of the tubes 25.

The space 28 beneath the sloping portions of the tubes 25 is utilized as a combustion chamber into which a suitable fuel, such as pulverized coal, is introduced through one or more burner openings 29 in the front wall 20. In order to enclose the combustion chamber on opposite sides there are provided two groups 30 and 3| of closely spaced upright water tubes located between the front wall 20 and the front edges of the refractory side walls I1. These tubes are exposed on their inner surfaces to the heat of combustion and they are enclosed on their outer sides by means of refractory material 33. This refractory 33 may be comparatively thin, since it is supported and cooled by the water tubes. The outer surface of y the refractory 33 is substantially flush with the outer surface of the adjacent side wall l1, and each group of water tubes 30 and 3| is offset outwardly from the inner surface of the adjacent side wall. This increases consider-ably the volume of the combustion space, and it utilizes the available floor space in an efficient manner. Furthermore, it facilitates the application of a steel casing to the outside of the setting.

At each side of the combustion chamber 28 and near the top thereof we provide a longitudinal header 35 to which the upper ends of the adjacent water wall tubes 30 and 3| are connected. The ends of the tubes are preferably staggered in order to maintain adequate ligaments in the headers. A row of tubes 36 extends upwardly from each header to provide steam releasers therefor, certain of these tubes extending forwardly to the header 22 and others extending rearwardly to enter the steam-and-water drum ID in a circumferential row. As shown particularly in Fig. 3, a space is provided between each side wall I! and the outermost tubes in the tube banks 54 and 25, so that the tubes 35 may extend along the inside of the side walls. These releaser tubes 36 are enclosed on their outer sides, in front of the side walls [1, by means of refractory material 38, which may be comparatively thin.

As shown particularly in Fig. 2, each header 35 is located in a vertical plane which is intermediate the plane of the releaser tubes 36 and the plane of the water wall tubes 30 or 3|. In other Words, the header is offset outwardly with respect to the releaser tubes and inwardly with respect to the water wall tubes. One advantage of this construction is that the header is located directly beneath the refractory material 38 and serves to support the weight thereof.

In order to supply water to the water wall tubes 30 and 3| we provide a longitudinal lower header 40 located at the bottom of the combustion chamber 28 and at the side thereof adjacent to the tubes 30. The lower ends of the tubes 33 are connected to this header, and the lower portions of the tubes 3| are bent laterally and extend at a slight downward slope across the combustion chamber and are likewise connected to the header. These sloping portions of the tubes 3| serve to support refractory material 42 which forms the floor of the combustion chamber. At the rear end of the header 4!] there is provided a header 43 which is connected thereto at substantially a right angle and is arranged below and parallel to the lower water drum II. The headers 48 and 43' may be integral with each other, or they may be joined by welding orotherwise. Two rows of water tubes 44 connect the water drum H to the transverse header 43.

When pulverized coal is to be used as a fuel, we preferably provide a depressed ash pocket 46 which extends across the rear of the combustion chamber directly in front of the bridge wall IS. A door 41 is provided in one or both sidewalls II to facilitate ash removal. One or more doors 48 are provided in the front wall 20, so that a steam lance may be inserted to blow the ashes rearwardly from the floor 42 into the pocket 45.

The refractory sidewalls I! extend forwardly for a substantial distance in front of the upright portions of the tubes 25, and hence are subjected to considerable heat from. the combus-t tion chamber. In order to prevent overheating and slagging of these walls we provide two upright water tubes 50 at each side of the furnace, these tubes being located adjacent to the forwardly extending portions of the wall II. The lower portions of these tubes are bent rearwardly to connect with the lower drum I I, and the upper ends of the tubes are connected to the adjacent water wall header 35.

In order to direct the hot gases from the combustion chamber 28 into proper contact with the water tubes, suitable baffles are provided. A baffie 52 of refractory material is supported by the front row of tubes l4 and fills the spaces between the tubes in this row. This bafile extends upwardly from the lower drum H to the tops of the upright portions of the rearmost tubes 25, and thence forwardly along the sloping portions of these tubes for about half their length. At each side the upright portion of the baffle is supported by a tube 54 connected at its lower end to the lower drum H and extending upwardly in alignment with the front row of tubes M. The upper portion of this tube is bent rearward- 1y to avoid interference with the releaser tubes 36, as shown in Fig. 1, and enters the upper drum III in alignment with the upper ends of the rear row of tubes l4 and in the same circumferential row as the releaser tubes. A bafile 55 extends downwardly from the upper drum [0 immediately in the rear of the front row of tubes l2, this baflle having forwardly and rearwardly projecting branches 56. Bafiles 51 extend forwardly from the rear wall l6 into the tube bank [2 in staggered relation to the rearwardly projecting branches 55. A gas outlet 58 is provided in the rear of the upper drum I0.

It will now be apparent that the hot gases from the combustion chamber 28 will flow upwardly around the front of the baflie 52 and thence rearwardly and downwardly between the baflies 52 and 55. The gases will then flow upwardly between the baffles 55 and 51 to the outlet 58. Most of the soot and fly ash which is carried out of the combustion chamber by the gases will be deposited at the rear of the lower drum I I. In order to prevent this material from piling up against the header 43 a partition or plate 60 (Fig. 1) is provided which extends downwardly from the drum H in the rear of the tubes 44 and header 43. Access to the fly ash deposit in the rear of this plate may be had through a door 6| in the side wall IT. This side wall is also provided with a door 62 in front of the plate 60 through which access may be had to the header 43 and tubes 44.

In order to prevent carry-over of excessive moisture from the steam-and-water drum Hi to the superheater 26, we have shown a transverse drum 64 mounted above the drum I i] and connected to the steam space thereof by means of tubes 65. The inlet ends of the superheater tubes 26 are connected to the upper portion of the drum 64. This steam drum 64 is provided with internal baflles 66 or other suitable means to separate water from the steam which is delivered to the drum by the tubes 65. The separated water is withdrawn from the drum through a tube 68 which leads downwardly along the outside of one side wall I! to the lower water wall header 4D.

The operation of the invention will now be apparent from the above disclosure. Pulverized coal or other suitable fuel is introduced through the burner openings 29 and burns in suspension in the combustion chamber 28. The hot gases flow upwardly into contact with the water tubes 25 and the superheater 26, thence downwardly in contact with the water tubes l4, and thence upwardly in contact with the water tubes I2 and through the outlet 58 to a suitable stack. Since the baffle 52 is located behind the water tubes 25, the upright portions of all these tubes are exposed to heat radiated rearwardly from the combustion chamber. This produces a rapid upward circulation through these tubes and avoids any possibility of steam-locking in the upper substantially horizontal portions of the tubes. Steam is generated very rapidly in the water tubes 25 and in the side wall tubes 30 and 3|, this steam flowing upwardly to the steam-andwater drum [0 where most of the water is separated from the steam. The steam then passes upwardly through the tubes 65 to the drum 64 and thence to the superheater 2 6. Substantially all the water which is carried by the steam into the drum 64 is deposited in the bottom of the drum and withdrawn through the tube 68. A sudden increase in the demand for steam will not cause a flooding of the drum 64, since one effect of the steam generation in the water wall tubes 30 and 31 is to maintain a high water velocity and a comparatively low static pressure in the header 40 to which the tube 68 is connected. Consequently water will escape from the drum 64 as fast as it can collect therein. Much of the ash from the fuel will be deposited directly in the ash pocket 46, from which it can be removed through the door 41, and such ash as falls to the floor 42 can be blown rearwardly into this pocket by means of a steam lance. The fly ash which is carried over the top of the baflie 52 by the hot gases will be deposited at the rear of the plate 60 and can be removed through the door 6|. The tubes 44 and the transVerse header 43 provide a simple means for supplying large quantities of water to the lower water wall header 4!], and they can be readily reached for inspection through the door 62. The front portions of the refractory side walls I! are well protected by the water tubes 50 from excessive heating or slagging. The arrangement of the water wall tubes 30 and 3| provides a maximum combustion space in a given floor area, and simplifies the application of a steel casing. The upper headers 35, by reason of their offset positioning, provide ample support for the weight of the refractory 38. The close spacing of the upright portions of the tube rows 25 aids in increasing the space available for the rearward travel of the combustion flame, while the wide spacing of the substantially horizontal portions of these tube rows aids in chilling any slag particles which may arise with the combustion gases and avoids the tendency of such particles to accumulate on the Water tubes and superheater. The steam generator is of simple and inexpensive construction, and yet capable of eflicient operation at comparatively high rates.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, means providing a combustion chamber in front of the tube bank, upright water wall tubes at one side of the combustion chamber, means connecting the upper ends of the water wall tubes to the steam-and-water drum, a longitudinally extending header to which the lower W ends of the water wall tubes are connected, means to supply water from the water drum to the header, a steam drum mounted above the steam-and-water drum, means to conduct steam from the steam-and-water drum to the steam drum, means in the steam drum to separate water from the steam delivered thereto, and a conduit through which the water thus separated may flow downwardly to said header.

2. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, means providing a combustion chamber in front of the tube bank arranged for the combustion of pulverized fuel in suspension, a longitudinally extending header located at the bottom of the combustion chamber and adjacent one side thereof, means to supply water from the water drum to the header, means including a row of water tubes extending laterally from the header and across the bottom of the combustion chamber to provide a closed water cooled floor,

from the water drum, and means providing an ash pocket located between the rear edge of the floor and the water drum and opening upwardly into the rear portion of the combustion chamber.

3. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, means providing a combustion chamber in front of the tube bank arranged for the combustion of pulverized fuel in suspension, a longitudinally extending header located at the bottom of the combustion chamber and adjacent one side thereof, means to supply water from the water drum to the header, a row of water tubes extending upwardly from the header to provide a water cooled wall for the adjacent side of the combustion chamber, a row of water tubes extending laterally from the header and across the bottom of the combustion chamber to provide a water cooled floor and thence upwardly to provide a water cooled wall for the other side of the combustion chamber, the rear edge of the floor being spaced forwardly from the water drum, and means providing an ash pocket between the rear edge of the floor and the water drum.

4. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, refractory side walls located on opposite sides of the tube bankand extending forwardly beyond the tube bank, means providing a combustion chamber in front of the tube bank arranged for the combustion of pulverized fuel in suspension, a longitudinally extending lower header located at the bottom of the combustion chamber and adjacent one side thereof, means to supply water from the water drum to the header, an upper longitudinal header at each side of the combustion chamber, a row of water tubes extending upwardly from the lower header to the upper header on the same side to provide a water cooled wall for the adjacent side of the combustion chamber, a row of water tubes extending laterally from the lower header and across the bottom of the combustion chamber to provide a water cooled floor and thence upwardly to provide a water cooled wall for the other side 'of the combustion chamber, the rear edge of the floor being spaced forwardly from the water drum, and means providing an ash pocket in the rear of the floor and between the forwardly extending portions of the refractory side walls.

5. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, refractory side walls located on opposite sides of the tube bank and extending forwardly beyond the tube bank, means providing a combustion chamber in front of the tube bank, a longitudinal header at each side of the combustion chamber adjacent the upper portion thereof, a row of water wall tubes at each side of the combustion chamber to provide water cooled walls in front of the refractory walls, the water wall tubes being connected at their upper ends to the headers, means to supply water from the water drum to the lower ends of the water wall tubes, and water tubes leading from the end portions of the water drum to the rear portions of the headers to protect the forwardly extending portions of the refractory side walls from the heat of combustion.

6. A steam generator comprising a transverse t e e edge o e oor being Spaced forwardly 7 steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, refractory side walls located on opposite sides of the tube bank, means providing a combustion chamber in front of the tube bank, a row of water wall tubes at each side of the combustion chamber to provide water cooled walls in front of the refractory walls, each row of water wall tubes being located in a plane which is offset outwardly from the plane of the inner surface of the adjacent refractory wall, means to supply water from the water drum to the water wall tubes, longitudinal headers to which the upper ends of the water wall tubes are connected, each header being located in a vertical plane intermediate the plane of the water wall tubes and the plane of the inner surface of the refractory wall, releaser tubes extending upwardly from the headers and thence rearwardly along the inner surfaces of the refractory walls to the end portions of the steam-and-water drum, and refractory material located outside the releaser tubes in front of the refractory walls and above the headers.

7. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, refractory side walls located on opposite sides of the tube bank, means providing a combustion chamber in front of the tube bank, a row of water wall tubes at each side of the combustion chamber to provide water cooled walls in front of the refractory walls, means to supply water from the water drum to the water wall tubes, longitudinal headers to which the upper ends of the water wall tubes are connected, releaser tubes extending upwardly from the headers and thence rearwardly between the tube bank and the refractory walls to connect with the end portions of the steam-and-water drum, a baflle of refractory material extending upwardly from the water drum, and two water tubes extending upwarlly from the water drum in supporting relation to the sides of the baflle, the upper portions of the last mentioned tubes being bent rearwardly and entering the steam-and-water drum below and rearwardly of the releaser tubes.

8. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of tubes connecting the drums, refractory side walls located on opposite sides of the tube bank, means providing a combustion chamber in front of the tube bank, a row of water wall tubes at each side of the combustion chamber to provide water cooled walls in front of the refractory walls, means to supply water from the water drum to the water wall tubes, longitudinal headers to which the upper ends of the water wall tubes are connected, releaser tubes extending upwardly from each header and thence rearwardly between the tube bank and the adjacent refractory wall to enter the adjacent end portion of the steam-and-water drum in a circumferential row, a baffle of refractory material extending upwardly from the water drum,. and two water tubes extending upwardly from the water drum in supporting relation to the sides of the bafile, the upper portion of each of the last mentioned tubes being bent rearwardly and entering the steam-and-water drum below and rearwardly of the adjacent releaser tubes and in the same circumferential row therewith.

MAX H. KUHNER. GUSTAV A. REHM.

7 CERTIFICATE OF CORRECTION. Patent no..2,:295,s55 7 August 25, '19u2.

MAX H. KUHNER, ET AL.

It is hereby certified thet error appears in the printed specification of the above numbered. patent requiring correction as follows Page 2, first column; line 50, for the words "the floor of? read "deleted floor for--; page 11., second column, line 5, for upwarlly read "upwardly"; and that the seid' Letters Patent should be bead with this correction'therein that .the same may conform to the record of the case in the Patent Office, v

Signed and sealed this 29th day of September, A. D. 19).;2.

Henry Van Arsdale, (Seal) Acting Comissioner of Patents.

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