US2173887A - Flue gas water heater - Google Patents

Description

Sept. 26, 1939.

J. l. SHUTE FLUE GAS WATER HEATER:

Filed Nov. 9, 1956 my x JMKZW W m w n 2 Patented Sept. 26, 1939 UNITED STATES PATENT OFFIC 4 Claims.

The invention relates to a Water heating system in which heating is effected by abstraction of heat from the products of combustion which usually pass ofi in a heated state through the 5 flue from a boiler or furnace.

It is well known that heating plants used in many establishments, such as laundries, hotels, etc., where steam is generated, are ineflicient because of the fact that a material portion of the ln heat of combustion is lost in the fiue gases which are hotter than necessary to provide the desired draft. Attempts have been made to abstract heat from flue gases but such attempts usually entail certain difficulties together with marked alteration of an existing installation.

A plentiful supply of hot water is necessary in establishments such as those indicated above. Hence, it is an object of the invention to provide an improved water heating system comprising a water tube flue gas water heater which is con nected to an open storage tank whereby free circulation of water is had, occluded gases are liberated and certain compounds in the water are dropped.

Another object is the provision of a water heating system that may be readily installed in an existing boiler installation without materially disturbing that installation.

A further object is the provision of a water heater in which the component elements are so constructed and arranged that a small friction head is presented and hence naturalcirculation of liquid may be utilized.

Another object is provision of a heater that is readily adapted to change in dimensions for accommodation to various conditions of installations.

A further object is the provision of a water heating system in which heating and circulation may be enhanced by introduction of steam thereto.

It is also an object of the invention to provide a flue gas water heater that permits accessibility to the adjacent boiler for cleaning and repairs with- 5 out material dismantling of the heater.

The invention has other advantages and objects which, together with the foregoing, will be apparent upon consideration of the following description in connection with the drawing in which:

Fig. l is a view, partly in section, showing a preferred embodiment of the invention.

Fig. 2 is an enlarged section taken on line 2-2 of Fig. 1.

In Fig. 1 is shown a section of the flue end of a boiler of known type. I represents generally the boiler which is provided with a plurality of fire tubes 2, the ends of which are fixed in tube sheet 3. The breeching comprises the smoke box, generally designated as 4, and smoke outlet con- 5 nection 5 through which it is connected to the stack 6. Within the stack is provided a damper l as is well known.

At a suitable elevation in the breeching or flue, oppositely disposed openings iii are provided. Reinforcing flanged members H are secured in place surrounding these openings HI and collars I2, I 3 are supported therein. It is understood that any equivalent construction may be utilized ,if the breeching is constructed of brick or masonry.

The heat exchange unit of the invention is made up of two sections generally designated as 54 and E5 in the drawing. As the specific constructions of these sections are substantially identical it is to be understood that the following description of section I4 applies equally well to section I5 in which similar parts are identified by similar primed reference characters. A header I6 is supported in collars l2, l3. Depending pipes ll, l8 and [9 are attached to header is in-any suitable manner such as weld metal 20. The lower ends of these pipes are similarly connected to a lower header 25. It is obvious that the construction provides a plurality of parallel paths for fluid to flow between headers l 6 and 25. This is of importance for it is necessary to have a given minimum heating surface if desired results are to be accomplished. If the heating .area is too small, large amounts of heat energy will be lost through the flue gases and insuflicient heating of water will take place. At the same time, however, if natural circulation of water is to be relied upon, it is necessary to minimize the friction head in the fluid circuit. This construction satisfies these requirements in a practical manner.

The end of header I6 is provided with a plug 26 through which is passed pipe 21. This pipe is provided with a valve 28 which is connected to the pipe 29 from a steam line (not shown). The pipe 21 terminates at a point within header It. This steam connection is provided for use when the system has been shut down and it is desired to quickly heat the water in the system when starting up or when an unusual demand is placed upon the system for supply of hot water. At such time valve 28 is opened to admit live steam whereby the rate of circulation is enhanced and, at the same time, the heat of vaporization of the water admitted in the form of steam is added to the circulating water.

Header 25 is provided with pipe unions 30 for a purpose that will be briefly described. Header 25 is also provided with a similar union 30'. This construction enables interconnection of sections l4 and I5 through elbows 3| and 32. It likewise permits ready disconnection of section [5 for such purposes as cleaning and repair. Further, it permits removal of the section if it be desired to use only section M, in which case ready connection may be made from header 25 to the remainder of the fluid circuit. On the other hand, by disconnecting union 30 and merely loosening unions 30, section l5 may be swung upwardly to facilitate cleaning of the fiues 2. Thereafter the section may be returned to and secured in position without disturbing the remainder of the installation.

The header member 16 is connected to reservoir tank through suitable tubular connectors 34. Header 25 is also connected to reservoir tank 35 through suitable connectors 33. To enhance the natural circulation of the liquid in the system connector 33 is connected to tank 35 below the level of connector 34. The flow of liquid through the system is thus as shown by the arrows. This flow and the rate of heating may be enhanced by introduction of steam through valve 23, as above described.

In Fig. 2 is shown a section on line 2-2 of Fig. 1. This view shows the use of pipe unions 3639 in pipes ll, [8 and 19. These unions were not shown in Fig. 1 in order to avoid confusion in the drawing. The purpose of the unions is two- )fold. First, this construction permits prefabrication of the parts. This feature permits assembly Within the breeching Without material dismantling thereof. Second, added lengths of pipe may be inserted in the unit whereby heating units of various lengths may be installed by using relatively few stocked parts. It is to be noted that two unions 38 and 39 are provided in pipe [9. The purpose of this construction is to provide access to inner union 3'! of the installation by the removal of the section of pipe between the unions 38 and 39 in pipe I9. Tank 38 is provided with a cover 40 which is preferably loosely seated thereon. A pipe 41 is provided for admitting liquid to and withdrawing liquid from the system. It is apparent that as many connections as are deemed desirable may be made to tank 35 and that the water withdrawn from the tank may be used for any desired purpose. For example, the water may be withdrawn and pumped into the boiler l in which case the system is used as a feed water heater. On the other hand, the water may be introduced into the hot water system of the establishment of which the installation is used. In either event advantage is obtained from the fact that certain compounds are dropped in tank 35 and at the same time storage in the open tank permits liberation of the occluded gases. This last mentioned feature is of particular importance since the occluded gases in a hot water system or a boiler are particularly undesirable because of the fact that they cause rapid corrosion therein. Furthermore, the elimination of the occluded gases materially increase the efiiciency of the pumping mechanism required to handle the hot water.

While the foregoing describes a specific structure representing a preferred embodiment of the invention, it will be readily understood that the invention is not limited to the particular construction since it may be practiced with other apparatus falling within the range of equivalents of that described.

What is claimed is:

1. The combination with a boiler having a smoke box at one end, a header extending transversely of said smoke box and suspended therein, a plurality of downwardly extending pipes attached to said header in parallel relation, said pipes being of adequate number and dimensions to present adequate heating surface and small friction head, a second transverse header below said first mentioned header, said second header being connected to said pipes, whereby a closed fluid circuit is provided, and means for introducing live steam longitudinally of the upper header whereby a single steam injector effects circulation through all of the vertical pipes.

2. In a heating system having a boiler, a flue, a flue gas water heater suspended therein, said heater comprising an upper section extending upwardly above the boiler flue. and a lower section adjacent the end of the flue, and means swingably connecting said lower section to the upper section whereby the lower section may be swung to a position that permits cleaning of the boiler flue.

3. A water heater comprising, a header, a plurality of pipes attached to said header and extending outwardly therefrom in parallel relation, a second header attached to the opposite ends of said pipes and a single-steam injection means in one of said headers to introduce steam longitudinally of the header to effect circulation through all of said pipes.

4. A water heater comprising, a header, a plurality of pipes attached to said header and. extending downwardly therefrom, a second header attached to the lower ends of said pipes, and a single steam injection means for introducing live steam longitudinally of one of said headers to effect circulation through all of the vertical pipes.

JAMES I. SHUTE.

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