US3918410A

US3918410A - Boiler for heating of water and generating of steam

Info

Publication number: US3918410A
Application number: US480857A
Authority: US
Inventors: Rolf Backman
Original assignee: Handelsbolaget Broderna Backman
Current assignee: Handelsbolaget Broderna Backman
Priority date: 1974-06-19
Filing date: 1974-06-19
Publication date: 1975-11-11
Anticipated expiration: 1992-11-11

Abstract

The present invention relates to a boiler comprising a furnace encircled by a number of water tubes which are enclosing fire tubes in which boiler the water tubes are jointed together to form a complete jacket encircling the furnace.

Description

United States Patent 1191 Vance 122/271 Backman Nov. 11, 1975 [5 BOILER FOR HEATING 0F WATERAND 653.216 7/1900 Cowley et a1. 122/269 GENERATXNG ()F STEAM 1948939 2/1934 Noack 1.22/24 2.030.265 2/1936 Nygaard 122/348 Inventor: Rolf Backman, Mo y Sweden 2429.916 10/1947 Belgau 122/348 [73] Assignee: fiandelsbolaget Broderna Backman, 2,587,530 2/1952 R0551 122/271 Kallered, Sweden v 22 i June- 9 197 Primary E.\'uminer1(enneth W. Sprague [21] Appl. No.: 480,857

' 57 ABSTRACT 52] US. Cl 122/271; 122/348 1 I Clf prese t inve ti n relates to a omprising a [58] Fleld of Search 122/24, 271, 348, 266, furnace encircled by a number of water tubes which 1 22/269 are enclosing fire tubes in which boiler the water tubes are jointed together to form a complete jacket encir- [56] References Cited cling the furnace UNITED STATES PATENTS 3/ 1893 5 Claims, 4 Drawing Figures US. Patent Nov. 11,1975 Sheet1of3 3,918,410

US. Patent Nov. 11, 1975 Sheet2 013 3,918,410

FIG. 2

US. Patent Nov. 11,1975 Sheet3of3 3,918,410

BOILER FOR HEATING OF WATER AND GENERATING OF STEAM The present invention relates to a boiler comprising a furnace, a first" water tank provided to be charged with the water to be heated, a'second water tank provided for the discharge of the heated water or the generated steam respectively and means provided to form a water connection between the two said tanks .which means are enclosing fire tubes provided to lead combustion gases from the furnace to a gas collecting room.

.Boilers of said type are nowadays usually in the form of, water tube boilers with the water circulating in tubes exposed to combustion gases, or fire tube boilers in which the water is enclosed in tanks through which are extending tubes through which the combustion gases are streaming. Both said types of boilers have a relatively complicated design and are expensive to produce. This disadvantage relates to water tube boilers which is the type which has to be used for higher pressure steam. Further, both types of boilers have to be dimensioned for a determined maximum-capacity and the boilers of said known types thereby show the disadvantage that if the effect taken off is lowered in a higher degree in relation to the maximum capacity condensation phenomenons will occur as a result of too low temperature in the spaces in which the combustion gases are streaming which low temperature at oil fired boilers usually occurs intermittently during the stand still periods of the oil burner which periods will be increased in length by lowered effect. Condensation results as .known in corrosion of the exposed surfaces especially by firing with sulphurous fuel.

The present invention has as an object to provide a boiler which shows a simple design especially in relation to water tube boilers and which boiler in spite of this can be made for very high pressures. The boiler ac- ,cording to the invention is, contrary to said known boiler ty.pes,.suitable to be manufactured by means of modern rational methods using several stations for part assembling.

Anotherobject by the invention is to provide a boiler which can be regulated within a very wide range of capacity without the risk for any condensation phenomena will occur at low effect.

The objects of the invention will be obtained by means of a boiler in which said means for the water connection between the two tanks are formed by a number of tubes. jointed together to form a jacket encircling the furnace.

In the enclosed drawings two embodiments of the boiler according to the invention are shown whereby FIG. I is a vertical section of a boiler according to the first embodiment;

FIG. 2 is a horizontal section along the line IIII in FIG. 1;

FIG. 3 is a detail in enlarged scale'in a section according to FIG. 2;

FIG. 4 shows a second embodiment in a vertical section.

According to the figures the main shape of the boiler is an erected cylinder. A jacket around the furnace 1 is formed by means ofa number of large tubes 2 closely which tank at its periphery is connected to said tubes 2 by means of narrower tubes 5. In the bottom tank 3 are a number of flanges 14 arranged to direct the stream of water from the tube 4 to the tubes 5 (see FIG. 2). The space between the tank 3 and the lower ends of the tubes 2 is covered with an annular band 6 and a sheet 7 formed to suit the outer wall formed by the tubes .2. The roof in the furnace I is formed by means of an upper, annular water or steam collecting tank 8 which by means of tubes 9 is connected to the tubes 2 and is provided with a discharge tube 23. The discharge tube 23 from the tank 8 is for taking off of the heated water respectively the generated stream if the boiler is provided as a steam generator. The tank 8 and the tubes 2 are tightly connected to each other by a sheet In a central hole 11 in the tank 8 an oil burner I3 is attached via a flange 12, which burner can be of the usual type.

A plurality of tubes 15 are extending through each of the tubes 2. The lower ends of the tubes 15 terminate in the furnace l and the upper ends terminate in an annular collecting chamber 18 for the combustion gases via a space 16 for each one of the tubes 2, separated from the inner space of the same and via a valve 17 manoeuverable between open and closed position by means of a lever 24 and an actuating bar 25. From the collecting chamber 18 the combustion gases are evacuable via exhaust tubes 19. According to the desired range of capacity regulation the boiler can be provided with valves 17 at all of the tubes 2 or some of them. By very little need for capacity regulation the valves can be excluded.

The boiler is completed with an outer covering 20 which encloses an insulation 21. Further, feet 22 are provided for of carrying of the boiler.

The boiler according to the second embodiment is mainly equal to the described first embodiment. According to FIG. 4 the mantle of the furnace l is formed by means of large tubes 2 joined to each other and through which the narrower tubes 15 are extending and are equal to the first embodiment. at their lower ends terminating in the furnace l and at the upper ends in the spaces 16 provided with valves 17. Further, the second embodiment comprises

outer covering

20, 21, a band 6, a sheet 7 and connecting tubes 5.

The two embodiments are, however, unequal in an important detail. At the embodiment according to FIG. 4 the upper part of the furnace 1 is provided with a number of tubes 26 placed with spaces in between them to form a squirrel cage" and with their lower ends terminating in an annular water tank 27 which is connected to the water rooms in the tubes 2 by means of connecting tubes 28. At their upper ends the tubes 26 terminate in a water tank 29 to which also the water rooms of the tubes 2 are connected by means of tubes 30. The tank 29 is provided with a discharge tube 31.

The other side of the tank 29 and the cage formed by the upper parts of the tubes 26 enclose, together with a sheet 32, a gas collecting space 33 which is connected to the spaces 16 via the valves 17. At the lower ends of the tubes 2 a further gas collecting space 34 is formed through which the tubes 5 are extending. The walls of the space'34 is formed by a water tank 35 with an inlet tube 36 and further by said band 6 and the sheet 37. The gascollecting space 34 is provided with an exhaust tube 38. The boiler is provided with a bottom 43.

The boiler according to FIG. 4 can be arranged to be fired in different ways. For example it can at its upper part be provided with an oil burner 44 equal to the boiler according to the first embodiment. The boiler can also be provided to be fired with solid fuel as is evident from FIG. 4. To this end the room in the center of the annular sheet 37 and the annular water tank 35 and on the bottom 43 is provided with a lining 39 which is fire resistant. At the lining 39 fire bars 40 are arranged and the space in question is reachable from the outside through a shutter 41. The necessary area for the shutter 41 is formed of an opening in the water tank 35 and by the arrangement that a number of the tubes 2 are shortened as evident from the figures. In the front of the shutter 41 it is not possible to arrange any connection tubes 5 to the water tank 35. As a substitute a number of connection tubes 42 is arranged which connect the shortened tubes 2 to adjacent tubes 2 of the normal length.

According to the type of fuel used, the furnace 1 in the bottom of the boiler can be arranged in different ways. It can for example be provided with a stoker machinery. It is also possible to arrange an oil burner in the bottom part of the boiler whereby the oil burner 44 is not necessary. Further. the boiler can be provided to be fired alternatively by solid or liquid fuel and can thereby be provided with a furnace for solid fuel as well as an oil burner which can be stationary or adapted to swing away from its working position.

When the boiler according to the first embodiment is fired a flame is directed from the oil burner 13 and downwards in the furnace l. The hot gases strike the bottom of the boiler and preheating of the water in the tank 3 will be the result. The combustion gases are thereafter streaming upwards through the tubes 15 to the spaces 16 through the valves 17 and out into the collecting chamber 18 and will be exhausted via the tube 19. The water will be charged to the boiler through the tube 4, will be circulated in the tank 3 guided by the flanges 14 and upwards through the tubes 5. From the tubes 5 the water continues through the tubes 2 streaming around the fire tubes 15 through the tubes 9 to the tank 8 and will via the discharge tube be taken off as hot water or steam.

As mentioned the water is pre-heated in the tank 3 but it is mainly heated in the tubes 2 where the tubes 15 form a large contact surface between the combustion gases and the water. Also in the tank 8 a heating of the water will occur.

When full capacity is desired all the valves 17 have to be opened and heat will be transformed from the gases to the water in all of the

tube arrangements

2, 15. If a lower capacity is desired a relevant number of the valves 17 has to be closed. At the shown embodiment with 26

tube arrangements

2, 15 the capacity may be regulated stepwise down with 1/26 of the total capacity; theoretically in the whole range from full capacity to 1/26 of the same. No combustion gas will pass through the

closed tube arrangements

2, 15 and consequently no condensation will occur in the same. In the furnace l the temperature is so high that no condensation will occur.

When the boiler according to the embodiment shown in FIG. 4 is fired by means of the oil burner 44 a flame is thrown downwards within the cage formed by the tubes 26 which thereby will be heated. In the lower part of the furnace l the flame returns and the gases are streaming in the narrow space between the tubes 26 and the wall formed by the tubes 2. Thereby some of the heat is transferred to the water in the tubes 2 and the tubes 26. In the space 33 where further heat is transformed to the tank 29 the combustion gases are directed downwards and into the spaces 16 on the assumption that the respective valves 17 are open (or that no valves 17 are arranged, as mentioned before). The combustion gases are streaming through the tubes 15 and will transfer heat to the surrounding, i.e. to the water in the tubes 2. The gases are collected in the space 34 and will be exhausted through the tube 38.

By firing with solid fuel through the shutter 41 or from an oil burner placed in the lower part of the boiler the combustion gases are streaming upwards whereby a certain part will escape up into the narrow space between the tubes 26 and the wall formed by the tubes 2 while a part will stream upwards in the space within the cage formed by the tubes 26 and escapes between said tubes outwards to the space 35. Consequently. the combustion gases are collected in the annular space 33 and are continuing in the way described before.

By means of the embodiment according to FIG. 4 the advantage is obtained that the boiler can be fired at its lower part with solid fuel which is not possible by the first embodiment because of the streaming ways at this embodiment for the combustion gases. Further, the way the combustion gases have to stream is prolonged which especially by fuel with long flames will give a better efficiency.

The present invention has the advantage that a separate jacket enclosing the furnace is eliminated while the water tubes are forming the wall around the firing room. This advantage will bring a lower manufacturing cost and further it has to be noted that the furnace jacket is not directly exposed to the combustion gases; between the inside and the outside of the same a water filled space is enclosed which will bring with it that the jacket gets a low outer temperature so that the insulation can be simplified. Further the boiler according to the invention can be provided with arrangements for capacity regulation within a very wide range.

The invention is not limited to the embodiments shown and described. As an example the boiler can be built with the cylinder formed by the horizontal tubes 2.

I claim:

1. A boiler comprising: a furnace, a first water tank to be charged with water to be heated, a second water tank from which heated water is to be discharged, a plurality of water tubes connecting said first and second water tank and being arranged parallel to each other, with adjacent tubes being joined together to form a jacket encircling said furnace and forming its outer wall, a plurality of fire tubes provided within said water tubes for passing combustion gases from said furnace therethrough, a gas collecting chamber connected to said fire tubes for receiving the combustion gases therefrom, the arrangement being such that said water tubes are subjected to combustion gases only on the surface thereof facing said furnace.

2. A boiler according to claim 1, which comprises firing means arranged at one end of the wall formed by said water tubes, said first water tank being arranged at the other end of said wall.

3. A boiler comprising: a furnace, a first water tank to be charged with water to be heated, a second water tank from which heated water is to be discharged, a plurality of water tubes connecting said first and second water tank and' being arranged parallel to each other, with adjacent tubes being joined together to form a jacket encircling said furnace and forming its vouter wall, a plurality of fire tubes provided within said water tubes for passing combustion gases from said furnace therethrough, a gas collecting chamber connected to said fire tubes for receiving the combustion gases therefrom, the arrangement being such that said water tubes are subjected to combustion gases only on the surface thereof facing said furnace, and valve means provided in at least some of said fire tubes, said valve means being actuable independently of each other.

4. A boiler comprising: a furnace, a first water tank to be charged with water to be heated, a second water tank from which heated water is to be discharged, a plurality of first water tubes connecting said first and second water tank and being arranged: parallel to each other, with adjacent tubes being joined "together to form a jacket encircling said furnace and forming its outer wall, a plurality of fire tubes provided within said first water tubes for passing combustion gases from said furnace therethrough, a gas collecting chamber connected to said fire tubes for receiving the combustion gases therefrom, the arrangement being such that said water tubes are subjected to combustion gases only on the surface thereof facing said furnace, and second water tubes arranged to form a cage within the space encircled by said first water tubes, said cage being heated by and guiding said combustion gases.

5. A boiler according to claim 4 comprising valve means provided in at least some of said fire tubes. said valve means being actuable independently of each

Claims

3. A boiler comprising: a furnace, a first water tank to be charged with water to be heated, a second water tank from which heated water is to be discharged, a plurality of water tubes connecting said first and second water tank and being arranged parallel to each other, with adjacent tubes being joined together to form a jacket encircling said furnace and forming its outer wall, a plurality of fire tubes provided within said water tubes for passing combustion gases from said furnace therethrough, a gas collecting chamber connected to said fire tubes for receiving the combustion gases therefrom, the arrangement being such that said water tubes are subjected to combustion gases only on the surface thereof facing said furnace, and valve means provided in at least some of said fire tubes, said valve means being actuable independently of each other.

4. A boiler comprising: a furnace, a first water tank to be charged with water to be heated, a second water tank from which heated water is to be discharged, a plurality of first water tubes connecting said first and second water tank and being arranged parallel to each other, with adjacent tubes being joined together to form a jacket encircling said furnace and forming its outer wall, a plurality of fire tubes provided within said first water tubes for passing combustion gases from said furnace therethrough, a gas collecting chamber connected to said fire tubes for receiving the combustion gases therefrom, the arrangement being such that said water tubes are subjected to combustion gases only on the surface thereof facing said furnace, and second water tubes arranged to form a cage within the space encircled by said first water tubes, said cage being heated by and guiding said combustion gases.

5. A boiler according to claim 4 comprising valve means provided in at least some of said fire tubes, said valve means being actuable independently of each other.