US2002463A - Steam boiler - Google Patents

Description

y 1935- E. G. BAILEY ET AL 2,002,463

. STEAM BOILER Original Filed Dec. 11, 1929 2 Sheets-Sheet l 0 0 O 0 O 0 O 0 O 0 0 C) 0 0 0 0 O 0 O 0 O 0 O 0 0 C O 0 O 0 O 0 f M3 INVENTORY if ATTORNEYS y ,1935. E, G, BAILEY ET AL 2,002,463

STEAM BOILER Original Filed Dec. 11, 1929 2 Sheets-Sheet 2 Jim W INVENTORS Patented May 21, 1935 UNITED STATES PATENT OFFICE STEAM BOILER Application December 11, 1929, Serial No. 413,200 Renewed February 8, 1934 21 Claims.

This invention relates to a boiler furnace, and more particularly to a boiler furnace in which pulverized coal or the like is used for-fuel.

An object of this invention is to provide a furnace of the type set forth of such construction and arrangement as to prevent excessive deposit of slag upon the tubes of the boiler proper.

The invention will be understood from the description in connection with the accompanying drawings in which Fig. 1 is a vertical section through an illustrative embodiment of the invention; Fig. 2 is a section along the line 2-2 of Fig. 1; Fig. 3 is a section similar to Fig. 2 showing a modification; Fig. 4 is a section similar to Fig. 1 partly broken away, showing another modification; and Fig. 5 is a section along the line 55 of Fig. 4.

In the drawings, reference character 1 indicates a furnace that is fired by pulverized fuel burners 2 along one wall of the furnace.'

A boiler of the Babcock 8: Wilcox type may be installed above the upper end of the furnace, only a portion of this boiler, namely, some of .the inclined tubes 3 and headers 4 and 5, being shown in Fig. 1. I

The furnace is provided with a floor 6, the edges of which are in close contact with the sides of the furnace to provide means for molten slag to collect in the lower portion of the furnace and be tapped out through the opening I. v

A row of water cooling tubes 8 is provided along one wall of the furnace. The lower ends of the tubes 8 are connected to a lower header 9 and the upper ends of these tubes to an upper header Ill. The upper header l may be connected to the steam space of the boiler by means of a pipe,

a portion of which is shown at H, and the lowerheader 9 may be connected to the water space of the boiler in the well known manner by a pipe, not shown. The upper portions of the tubes 8 are bent inwardly and then outwardly, as indicated at l2, to form a sort of arch. The tubes may be lined with tile or the well known Bailey blocks. The side walls of the furnace are also provided with tubes and headers similar to the front wall that are connected to the steam space and the water space of the boiler in a similar manner.

A row of tubes I3 is provided along the wall of the furnaceopposite the tubes 8, these tubesbe-,

ing connected to a lower header l4 and an upper header l that are in turn connected to the cirzulation system of the boiler. Rows of inclined ;ubes l5 and I! extend across the upper portion 31' the furnace from the header !5 to the header gases impinges directly against either the tubes in the row IE or the row I! and is thereby sepl8 that is located near the header Ill. The tubes l6 may be arranged in groups of three tubes in each group, as indicated in Figs. 2 and 3 with refractory blocks or tile l9 resting upon one of the tubs between the other two of each group as indicated in Fig. 2. The tubes I! may also be ar- 5 ranged in groups of three, as indicated in Fig. 3. The groups of tubes in each row of tubes are spaced apart and the groups in the respective rows are staggered with respect to each other.

Fuel, such as pulverized coal, is projected into the furnace from'the burners 2 preferably in a slightly downward direction so that some of the slag will be thrown out upon the bottom or floor of the furnace as the gases curve and pass upwardlybetween the groups of tubes in the rows I6 and H. The hot gases containing slag will impinge upon the groups of tubes in the row l6, some of the slag being caught upon these groups of tubes. The gases then make a sharp turn to pass between the groups in the upper row, a portion also impinging directly upon such tubes, causing more of the slag. to collecton the tubes IT. The molten'slag that is in suspension in the arated from the gases The groups of tubes are sufficiently far apart to prevent the slag from bridging the spaces between the groups. The slag that collects upon the tubes either drips downwardly and passes to the bottom of the furnace from which it is withdrawn through the opening 1, or it collects in relatively large lumps which break off and fall into the molten slag on the furnace floor. A wall 20 of refractory material closes the space between the header l8 and the lowerportion of the boiler proper.

' A transverse header 2| is located at the rear wall of the furnace above the header l5 and is connected by a row of tubes 22 that extend inwardly and then outwardly to the header 24 that is located outside of the furnace. The tubes 22 may be lined with tile 23. One or more recirculating tubes 25 outside of the furnace may connect the headers 2| and 24. The headers 2| and 24 are connected to the circulation system of the boiler, a portion of the connection 26 from the upper header 24 which leads to the steam space of the boiler. being shown. The tubes 22 extend inwardly as indicated at 21, substantially into contact with the row of tubes I1 and refractory filling material 28 fills the space below the portion 21 between the portion 21 and the tubes Hi. This will cause the hot products to pass forwardly from the rear wall of the furnace benected to the circulation system of the boiler for water to pass through them and steam to be generated, these tubes may be superheater tubes through which steam from the steam space of the boiler passes. The space between the tubes 3, H and 22 serves as a secondary combustion space or chamber for gases that pass across the slag screen tubes before they reach the boiler tubes 3, and the tubes 22 constitute a means for cool-- ing the walls of such space or chamber.

In the modification shown in Fig. 4, the upper ends of what may be called the front and rear walls of the furnace are shown at 30 and 3|, respectively, with front wall tubes 32 and rear wall tubes 34 connected to upper headers 33 and 35, respectively. The furnace wall tubes are connected to the circulation system of the boiler as above explained in connection with Fig. 1. A transverse header 36 is located near the upper end of the front wall of the furnace on the outside thereof and is connected by nipples 31 to the lower ends of the down-take headers 5 of the boiler proper. A transverse header 38 is provided near the upper end of the rear wall of the furnace on the outside thereof and is connected by means of nipples 39 to the lower ends of the uptake headers 4. Slag collecting tubes 40 and 4| extend across the upper portion of the furnace between the headers 36 and 38 and water passes through these tubes in parallel with the water that passes through the tubes 3 of the boiler proper. Tile 42 are applied to the tubes 60 at spaced intervals and tile 43 are applied to the tubes 4! at spaced intervals in staggered relation to those in the lower row, thereby causing the slag that is entrained in the hot gases to impinge against these surfaces and collect thereon in a manner similar to that'above described in connection with the group of tubes in the rows l6 and I'll.

It will be apparent that the inwardly extending tube portions 12 in Fig. 1 cooperate with the inwardly extending arch formed by the material 28 to decrease the flow area for the gases as they leave the furnace and flow over the slag removing tubes. As a result the velocity of flow of the gases through the slag removing tubes is materially increased with the result that the gases and slag are caused to impinge upon the tubes so as to cause such slag particles to adhere thereto.

In operation, a fuel such as pulverized coal is introduced through the burners 2 in a downward direction toward the floor of the combustion chamber on which a quantity of slag is accumulated, and the arrangement is such that the surface of the accumulated slag is maintained in a molten condition by the heat of combustion. The gases are subjected to a change in direction of flow above the molten slag so that a large amount of the slag entrained in the gases is thrown downwardly onto the floor of the combustion chamber and added to the molten pool which constitutes both a source of radiant heat and a means of collecting and retaining the slag particles thrown downwardly from the combustion gases. The excess of molten slag can be removed in any desired manner, such, for example as periodic tapping through the opening 7. After the change in their direction of flow, the gases pass upwardly and impinge upon the inclined tubes Ill and I9 so that additional slag is deposited upon said tubes from whence it flows or drips downwardly into the molten pool at the bottom of the furnace chamber. Some slag may adhere to the tubes and build up into relatively large chunks which ultimately break off and fall'by their own weight into the molten pool below. The tubes also cause an intimate mixing of the gases so that any unburned particles of fuel will be consumed at that point. I

Above the slag removing tubes I 6 and H, the gases flow toward the boiler tubes 3 across what may be termed a secondary combustion space, the lateral wall of which is cooled by the bank of wall tubes 22. In flowing across this space any slag particles remaining in the gases are subjected to the cooling effect of the wall tubes 22 and the boiler tubes 3 and are chilled sufficiently to prevent their adhering to the boiler tubes through which they subsequently pass. As shown in Figs. 1, 4 and 5, the tube rows in the boiler bank 3 adjacent the secondary combustion space are spaced further apart than the remaining tube rows to thereby form a slag screen for the tubes in the remaining rows. It will be apparent that the narrowing of the gas pass adjacent the slag removing tubes l6 and I 1 increases the velocity of gas flow through said tubes, with the result that the entrained slag impinges upon such tubes with considerable force. The circuitous path of flow of the gases through the staggered groups of tubes assists in expelling the slag from the gases and depositing it on the slag collecting tubes.

By arranging the tubes in each lower group I6 in the form of a V each side of these groups will cause the gases to impinge effectively upon the groups of slag screen tubes H in the upper row. Tubes ll forming groups may be arranged so as to present concave surfaces to the flow of gases thereby causing ash and dust particles and slag to be caught more effectively.

We claim:

1. In a boiler furnace, a burner for introducing pulverized slag forming fuel into said furnace, and rows of groups of slag collecting tubes extending across the upper portion of said furnace above said burner, each group being wider than twice the diameter of one tube.

2. In a boiler furnace, a burner for introducing pulverized slag forming fuel into said furnace, and horizontal rows of groups of slag removing tubes extending across the upper portion of said furnace above said burner, the groups of one row being staggered with respect to the groups of the other.

3. In a boiler furnace, a burner for introducing pulverized slag'forming fuel into said furnace, and horizontal rows of staggered groups of slag collecting tubes extending across the upper portion of said furnace above said burner, said tubes being so located as to leave a combustion space between them and the boiler.

4. The combination of a furnace having a combustion chamber, means for introducing a mixture of pulverized slag forming fuel and air into said combustion chamber so as to deposit a quantity of slag on said floor and maintain the surface thereof in a molten condition, horizontal rows of staggered groups of slag removing tubes extending across the upper portion of said furnace in the path of gas flow, and means for decreasing the fiow area for the gases of combustion adjacent said slag removing tubes.

5. In a furnace, inclined gas mingling slag collecting tubes extending across the upper portion of said furnace, said tubes being arranged in rows of groups, the groups of tubes in one of said rows being arranged to present a concave surface to the flow of gases.

6. In a furnace, horizontal rows of staggered groups of slag removing tubes extending across the upper portion of said furnace, a baiiie on said tubes at one end thereof to decrease the flow area for gases across said tubes, and an enlarged combustion chamber beyond said tubes.

7. In a water tube boiler having a furnace, a burner for introducing pulverized slag forming fuel into said furnace and a plurality of rows of obstructions extending across the gas flow from said furnace before the gas reaches the boiler tubes, the obstructions in one row being staggered with respect to those in another row and each obstruction comprisingat least two spaced cooling tubes and filling material between them.

8. In a water tube boiler having a furnace, a burner for introducing pulverized slag forming fuel into said furnace and a plurality of rows of obstructions extending across the gas flow from said furnace before the gas reaches the boiler tubes, the obstructionsin one row being staggered with respect to those in another row and each obstruction comprising at least two cooling tubes located sufliciently close together to enable slag from the combustion gases to fill the space between the tubes of each obstruction.

9. In a steam boiler, a furnace, means for projecting a slag-forming fuel towards the bottom of said furnace, spaced boiler tubes and spaced slag screen tubes contacted by hot gases from said furnace, said slag tubes being located on the furnace side of said boiler tubes and being arranged in groups with the spaces between groups in a direction across the gas stream substantially wider than the spaces between boiler tubes and between the tubes in each group.

10. In a steam boiler, a furnace, means for projecting a slag-forming fuel towards the bottom of said furnace, spaced boiler tubes and spaced slag screen tubes contacted by hot gases from said furnace, said slag tubes being located on the furnace side of said boiler tubes and being arranged in groups with the tubes in groups more closely spaced than the boiler tubes and with the spaces between groups in a direction across the gas stream, wider than the spaces between boiler tubes.

11. In a steam boiler, a furnace, spaced boiler tubes and spaced slag screen tubes contacted by hot gases from said furnace, said slag screen tubes being located on the furnace side of said boiler tubes and being arranged in staggered groups with the spaces between groups wider than the spaces between boiler tubes.

12. In a steam boiler, a furnace, spaced boiler tubes and spaced slag screen tubes contacted by hot gases from said furnace, said slag screen tubes being located on the furnace side of said boiler tubes and being arranged in staggered groups, the tubes comprising each group being staggered with the spaces between groups wider than the spaces between boiler tubes.

13. In a steam boiler, a furnace, spaced boiler tubes and spaced slag screen tubes contacted by hot gases from said furnace, said slag screen tubes being located on the furnace side of said' boiler tubes and being arranged in groups of staggered tubes with the tubes in the groups more closely spaced than the boiler tubes and with the of inclined-water tubes in said furnace between said fuel discharge means and boiler and forming a combined gas-agitating and slag-collecting screen, the tubes ofeach row being grouped, with the groups arranged in staggered relation with respect to the groups of adjacent rows, and

means on the tubes presenting hotter surfaces than the body of the tubes and whereby slag col-.

lectingthereon will be maintained in a molten condition.

15. In a steam generator, a furnace, a steam boiler thereabove, means for discharging a stream of slag-forming fuel into said furnace in a direction to cause molten slag to collect at the bottom thereof, and a water tube screen comprising rows of inclined water tubes in said furnace between said fuel discharge means and boiler and forming a combined gas-agitating and slag-collecting screen, the tubes of each row being arranged in staggered relation with respect to the tubes of an adjacent row, and means on said tubes presenting hotter surfaces than the body of the tubes and whereby slag collecting thereon will be maintained in a molten condition.

16. The combination with a steam boiler having a horizontally inclined bank of steam generating tubes arranged in a heating gas pass, of a furnace having a heating gas outlet below said tube bank, one of the vertical walls of said furnace having cooling fluid tubes lining the same from the lower end thereof to a level adjacent said tube bank, means for discharging a stream of slag-forming fuel into said furnace at a point opposite said fluid cooled wall, a row of horizontally inclined slag screen tubes extending across said furnace at said heating gas outlet and above said fuel discharge means, and said slag screen tubes having one end terminating adjacent said fluid cooled wall at a level intermediate the height thereof.

1'7. The combination with a steam boiler having a horizontally inclined bank of steam generating tubes arranged in a heating gas pass, of a furnace having a heating gas outlet below said tube bank of restricted cross-sectional area, one of the vertical walls of said furnace having cooling fluid tubes lining the same from the lower end thereof to a level adjacent said tube bank, means for discharging a stream of slag-forming fuel into said furnace at a point opposite said fluid cooled wall, a row of horizontally inclined slag screen tubes extending across said furnace at said heating gas outlet and above said fuel discharge means, said slag screen tubes having one end terminating adjacent said fluid cooled wall at a level intermediate the height thereof, and refractory on said slag screen tubes for maintaining the slag collecting thereon in a molten condition.

18. In a furnace, means for producing high temperature gases carrying slag-forming par- I by said gases and staggered relative to said first named groups being arranged in formations converging in the direction of gas flow.

19. In a furnace, means for producing high temperature gases carrying slag-forming parforming a combustion chamber with a heating gas outlet in its upper end, means for-burning a slag-forming fuel in suspension in said combustion chamber, a steam boiler positioned above said furnace and comprising a horizontally inclined bank of steam generating tubes arranged in-rows above said heating gas. outlet, the tube rows in said bank adjacent said gas outlet being spaced further apart than the remaining tube rows to form a slag screen for said remaining tube rows, and a plurality of staggered rows of refractory-covered fluid cooled tubes extending across a high temperature portion of said heating gas outlet and substantially below said boiler slag screen and forming a furnace slag screen for removing molten slag from'the heating gases prior to their contact with said boiler slag screen.

21. In combination, a furnace having walls forming a combustion chamber with a heating gas outlet in its upper end, means for burning a slag-forming fuel in said combustion chamber, a steam boiler positioned above said furnace and comprising a bank of steam generating tubes arranged in rows above said heating gas outlet, the tubes in the rows of said bank nearest said gas outlet being relatively arranged to form a slag screen for the tubes in the remaining rows of said bank, and a plurality of staggered rows of fluid cooled tubes extending across a high temperature portion of said heating gas outlet and substantially below said boilei slag screen and forming a furnace slag screen for removing molten slag from the heating gases prior to their contact with said boiler slag screen.

ERVIN G. BAILEY. HOWARD J. KERR. RALPH M. HARDGROVE.

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