US3918411A

US3918411A - Supercharged boiler

Info

Publication number: US3918411A
Application number: US501408A
Authority: US
Inventors: Walter Wolowodiuk
Original assignee: Foster Wheeler Energy Corp
Current assignee: Foster Wheeler Energy Corp
Priority date: 1974-08-28
Filing date: 1974-08-28
Publication date: 1975-11-11
Anticipated expiration: 1992-11-11
Also published as: JPS5148001A; CA1028906A; JPS529764B2; ES440545A1; GB1476604A

Abstract

A supercharged boiler which can be started up in less time is usually required to place boilers in operation. An economizer evaporator and superheater are all contained within a pressure vessel and the combustion gases operate a supercharger which furnishes air to the burners, so that during start-up the supercharger can be run from an independent drive motor to pressurize air and raise temperatures within the boiler to prevent the creation of large temperature gradients when the boiler is started up.

Description

United States atet 1191 1111 3,918,411

Wolowodiuk 5] Nov. 11, 1975 SUPERCHARGED BOILER 3 29.6 2 1/1966 Mirigay 1. 122/494 x Inventor: Waker Wolowodiuk, New 1 63.42 8/1966 Gorzegno. 122/240 X Providence, NJ. PIII7I(II' E.\'anzlnerKenneth W. Sprague Asslgneei 9 Wheeler Energy Corporation, Attorney, Agent, or Firm-Marvin A. Naigur; John E.

Lwmgswn, Wilson; John P. De Luca [22] Filed: Aug. 28, 1974 21 Appl. No.: 501,408 [57] ABSTRACT A supercharged boiler which can be started up in less [52] us CL 122/477, 122/1 122/494 time is usually required to place boilers in operation. [51] Int. CH 6 7/l2 F22B 33/18 An economizer evaporator and superheater are all [58] Field H R 24OR 333 7 R contained within a pressure vessel and the combustion 122/477 gases operate a supercharger which furnishes air to the burners, so that during start-up the supercharger [56] References Cited can be run from an independent drive motor to pressurize air and raise temperatures within the boiler to UNITED STATES PATENTS prevent the creation of large temperature gradients 1,995,034 3/1935 Mayo 122/477 hen the boiler is started up, 2,663,144 12/1953 Nordstrom et a1 60/3918 3,208,832 9/1965 Blaskowski 122/7 X 4 Claims, 1 Drawing Figure U.S. Patent Nov. 11, 1975 BACKGROUND OF THE INVENTION There are many uses for boilers which can be put into operation in a relatively short time. An example is found in electric power plants where loads varry in the course ofa day due to a wide variation in the power requirements of consumers during the daily cycle. It is often desirable to have a boiler to provide power for all but the peak loads because such a boiler can be fairly large and run at high efficiency if the energy it must produce is not made to vary over a wide range. The peak loads can be met by using an auxiliary boiler to furnish additional power.

There are several problems associated with the use of an auxiliary boiler to furnish additional power during peak periods of electric use. For one, boilers cannot usually be started up, that is, put into operation, in a short time. This is so because when the boiler is not in operation the heat transfer surfaces within it are at a temperature many hundreds of degrees below the temperatures reached by these surfaces during operation. When the boiler is started up, several surfaces immediately become very hot and are adjacent to other structure which is relatively cool. The creation of large temperature gradients often results in the failure of material.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome drawbacks found in the prior art such as those discussed above. Accordingly, the furnace section and convection sections of a steam generator are placed within a pressure vessel and the exhaust gases from the steam generator are used to drive a turbine which in turn drives a compressor which forces hot air downward in the space between the furnace and convection sections and the pressure vessel to burners at the bottom of the steam generator, the air being mixed with fuel at the burners to serve as combustion air, the compressor being operable by means other than the turbine during start-up to pressurize and thus heat the air so that on its way to the burners the air will preheat the steam generator and thereby prevent the creation of large temperature gradients during start-up.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a front view, partly in section, showing a steam generator made in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing shows a steam generator indicated generally as having a pressure vessel 12 which includes a generally cylindrical portion 14 and a top closure 16 which at its periphery is integral with the cylindrical portion 14 and a bottom closure 18 which at its periphery joins the bottom of the cylindrical portion 14. Feedwater enters through a line 20 where it flows into a header 22 to flow into an economizer platen 24. The water flows upward through the economizer platen 24 and leaves it to flow into a header 26 then out of the pressure vessel 12 through a line 28 which passes downward to below the boiler 10 and then upward through the bottom closure 18 thereof to the feed pipes 30 which connect with a header 32 which direct the water through connecting pipes 34 to evaporator tubes 36. The evaporator tubes 36 are vertical and are either joined to each other or are joined by fins so that the evaporator tubes 36 define an hermetic cylindric furnance section 38. The evaporator tubes 36 extend upward to a level 40 where they extend inward and upward for a short distance. Connecting tubes 42 join to evaporator tubes 36 adjacent the ends thereof and lead to a header 44 which communicates through pipes 46 with a header 48. The header 44 is circular in plan,.

whereas the header 48 is square in plan and therefore it is necessary to have two headers and to join them by the pipes 46.

The header 48 connects with a top header 50 through tubes 52 which pass from the header 48 directly upward to the header 50 which is placed within the pressure vessel 12 adjacent to the top of the cylindrical portion 14 thereof. The tubes 52 are joined together or to fins so that they define a convection section 53 sur rounded by an insulation Wall 54 which is cylindrical generally but which has several portions of increased wall thickness as can be seen from the drawing.

The top header 50 is connected by a pipe 56 with a header 58 which is connected to a platen 60 which at its upper portion, exhausts into a header 62 which is connected through a pipe 64 to a header 66 which feeds into a platen 68. The platen 68 extends upward to a header 70 which connects through a downward line 72 which passes through an annular space 74 between the insulation wall 54 and the pressure vessel 12 to a header 76. The header 76 feeds a platen 78 which extends up to a header 80 which is just above the header 76 and which is connected to a steam line 82.

The platen 78 constitutes a superheater which is screened from the hot gases by the economizer platen 24. Since the economizer platen 24 is cooled by water which is at a much lower temperature than is the superheated steam within the superheater platen 78, the economizer platen 24 is much better able to withstand the hot gases than is the platen 78. In operation, the feedwater which enters the line 20 flows through the header 22 to the platen 24 where it is heated within that platen. The water flows from the header 26 through the pipe 28 and into the header 32 to the evaporator tubes 36 which envelop the furnace 38. While passing upward through the tubes 38, the water is heated with some of it becoming steam. Passing into the

headers

44 and 48 the water and/or steam passes up to the header 50 through the line 52 where it is further heated. Thereafter the water and/or steam flows down through the line 56 to the header 58 and then successisvely through the platen 60 and the

headers

62 and 66 to the platen 68 where the steam is collected in the header 70 and then fed through the line 72 to the header 76. Thereafter the steam is led through the platen 78 where it is superheated to be collected at the platen 80 and then flowed out through the steam pipe 82.

Fuel is introduced through a fuel line which is connected through lines 92 and 94 to burners 96 and 98 respectively. The fuel is burned within the furnace 38 so that the combustion gases pass upwardly over the

platens

24, 78, 60 and 68. The gases are collected under the top closure 16 and passed through an exhaust duct 100 to a turbine 102 which drives a compressor 104. Exhaust gases are vented through a stack 106. The turbine 104 compresses air from the atmosphere and forces it through the duct 108 to the annual air space 74 between the insulation wall 54 and the cylindrical portion 14 of the pressurized vessel 12. Thereafter the air passes down through an annular space 110 between the evaporator tubes 36 and the cylindrical portion 14, to the space 111 immediately above the bottom closure 18.

Above the air space 111 is a burner wall 112 in which are mounted the burners 96 and 98 and which at its periphery is joined with the evaporator tubes 36 adjacent the lower ends thereof. The air below the burner wall 112 passes through the burners 96 and 98 to mix with the fuel therein and provide combustion air.

During start-up the compressor 104 is driven by a motor 112 through a shaft 114 to compress air and feed it through the air duct 108 into the air space 74 and through the air space 110 to the burners 96 and 98. Passing the compressed air raises the temperature of the structure within the pressure vessel 12 so that within a very short time the burners 96 and 98 can be fired and the boiler started up without the creation of any large temperature gradients.

The foregoing describes but one preferred embodiment of the invention, other embodiments being possible without exceeding the scope thereof.

What is claimed is:

l. A supercharged steam generator comprising:

a generally cylindrical pressure vessel having a top closure and a bottom closure;

a gas outlet in said top closure;

a plurality of vertically extending evaporator tubes defining the wall of a furnace section within and at the lower portion of said pressure vessel for flowing water to be heated to steam;

a convection section within said pressure vessel directly above said furnace section;

a first annular air space between said convection sec tion and said pressure vessel;

a second annular space between said convection section and said pressure vessel;

said first, and second air spaces being sealed from said furnace section and said convection section;

a supercharger comprising:

a drive motor;

a turbine; and

a compressor; said compressor being drivable by said turbine and said motor;

and an air duct connecting said compressor to said second air space at a location adjacent said top closure; and

a burner adjacent to the lower portion of said furnace section, and

an exhaust duct connected between said turbine and said gas outlet for flowing combustion gases to said turbine; whereby when said drive motor is actuated to drive said turbine, gas will be compressed and forced through said air duct into said second air space to flow to said first air space and to said burner to heat said furnace section and said convection section by exchanging heat with both of said sections so that thereafter fuel may be fed to said burner to be mixed with said air and combusted to heat said heat transfer tubes in said furnace section and said convection section so that combustion gases will flow through said duct to drive said turbine so that said turbine can then supply compressed air to said second and first air spaces and said burner.

2. The supercharged steam generator defined in claim 1 wherein said convection section includes a superheater.

3. The supercharged steam generator defined in claim 2 wherein said convection section includes an economizer.

4. The supercharged steam generator defined in claim 3 wherein said economizer is placed below said superheater and above said furnace section to shield said superheater from said furnace section.

* l l l

Claims

1. A supercharged steam generator comprising: a generally cylindrical pressure vessel having a top closure and a bottom closure; a gas outlet in said top closure; a plurality of vertically extending evaporator tubes defining the wall of a furnace section within and at the lower portion of said pressure vessel for flowing water to be heated to steam; a convection section within said pressure vessel directly above said furnace section; a first annular air space between said convection section and said pressure vessel; a second annular space between said convection section and said pressure vessel; said first, and second air spaces being sealed from said furnace section and said convection section; a supercharger comprising: a drive motor; a turbine; and a compressor; said compressor being drivable by said turbine and said motor; and an air duct connecting said compressor to said second air space at a location adjacent said top closure; and a burner adjacent to the lower portion of said furnace section, and an exhaust duct connected between said turbine and said gas outlet for flowing combustion gases to said turbine; whereby when said drive motor is actuated to drive said turbine, gas will be compressed and forced through said air duct into said second air space to flow to said first air space and to said burner to heat said furnace section and said convection section by exchanging heat with both of said sections so that thereafter fuel may be fed to said burner to be mixed with said air and combusted to heat said heat transfer tubes in said furnace section and said convection section so that combustion gases will flow through said duct to drive said turbine so that said turbine can then supply compressed air to said second and first air spaces and said burner.