US2065782A - Steam generating and superheating installation - Google Patents

Description

Dec. 29, 1936. J. E. woon STEAM GENERATING AND SUPERHEATING INSTALLA'X'IIIOIIv Filed Jan. 21. 1936 INVENTOR JOHN E. wooo.

ATTO R N EY Patented Dec. 29, 1936 UNTED STATES PATENT QFFIQE STEAM GENERATING AND SUPERHEATING INSTALLATION John Edwin Wood, Eltham, England, assigner to The Superheater Company, New York, N. Y.

12 Claims.

This invention relates to steam generating and superheating installations, and has particular reference to a method of. and means for protecting the superheater elements of such installations during the periods of raising steam pressure in the respective boilers.

It will be realized that it is important to maintain superheater elements at all times at a safe temperature, Whether the superheaters be of the convection or radiant type, and in some installations provisions are made for flooding the superheaters during pressure raising. Instead of flooding, however, protection can be afforded to steam superheaters during these periods by circulating steam through them. Frequently, during these periods of pressure raising, steam is passed from the boiler through the superheater elements to prevent the latter being overheated, the steam after flowing through the superheater being discharged to Waste through the drains or blow-downs of the superheater. Thus there is waste of pure or treated Water and of heat, and it follows that Where large boilers are concerned the cost of the water and heat so wasted amounts to a'relatively large sum.

Of the methods which have been proposed of protecting steam superheaters in boilers during pressure raising periods probably the most enicient is flooding, assuming the means to effect this to be properly designed, but, nevertheless, ooding is objectionable in certain respects, as is well known to those engaged in the art. Amongst the other methods of protection which have been proposed is o-ne which, although using steam as the cooling medium, seeks to eliminate or minimize the waste of pure water and heat above mentioned.

According to such known method a saturated steam range is provided in the boiler house with valve controlled connections to the various superheaters, whereby the superheater of a boiler being brought up to pressure is isolated from said boiler and saturated steam from the saturated steam range is passed through it into the main superheater steam range of the boiler house. Another known method, which purposes to eliminate Waste of heat and water, consists in circulating steam generated in the boiler during pressure raising through the superheater to cool the elements of the latter, and passing such steam to a feed water heater where the heat is transferred from the steam to the feed Water, the steam condensed, and the condensate returned to the feed system.

The present invention seeks to provide an improved, simple, cheap and efficient method of, and means for, protecting a steam superheater of a boiler from overheating during the firing up or pressure raising period, which, while being such as to avoid heat and water losses, shall be such as to necessitate the consumption of a minimum of power from a source other than the said boiler.

It also is an object of the invention to provide a method of, and means for, protecting a steam superheater of a boiler from overheating during pressure raising which shall avoid the use of. additional large stop valves, and shall employ apparatus occupying very little space; further, the additional piping required need be of relatively small diameter only, and this fact will assist materially in obtaining an efcient apparatus at relatively low cost.

According to this invention the superheater of a boiler is protected against overheating during pressure raising in the boiler by flowing through the superheater steam generated in the boiler, and, by means of an appropriate apparatus included in a local circuit, returning said steam to the said boiler, there being delivered to said apparatus, and thence into the boiler, aqueous fluid under a pressure above that obtaining in the boiler, which fluid in flowing through said apparatus induces the flow of steam through the superheater and on leaving said apparatus carries the said steam with it into the boiler.

The apparatus which by means of aqueous fluid under pressure flowing through it induces the steam flow through the superheater and returns it to the boiler, and which may be termed an energyY converter, comprises a chamber connected to the outlet header of the superheater to receive steam therefrom, and a converging nozzle in said chamber from which nozzle the said aqueous iiuid is directed into a diverging tube, the inlet of which is connected to said chamber. The aqueous fluid may be either steam .or Water and is at a pressure above that obtaining in the boiler with which the superheater and energy converter are associated, so that it is able to enter the boiler against the boiler pressure.

Where the aqueous uid employed as the power medium in the energy converter is steam, such steam preferably would be saturated steam from another boiler, or from the saturated steam range of the boiler house if such range be provided, but it may be steam from the boiler in Which pressure is being raised, the pressure of the steam in this case being increased to the necessary extent by an appropriately driven pump. Should the aqueous uid be water, it may be taken from the water space of the boiler with which the superheater under protection is associated or from the feed range of the boiler house. In the former case, the water may be placed under the necessary pressure by a pump driven by any appropriate motive means, as for example an electric motor, and in the latter case the pressure of the feed water, if necessary, may be increased by a pump.

In order that the manner in which the invention may be put into practice may be better appreciated, certain embodiments of the invention, selected as examples, will now be described with reference to the accompanying drawing, in Which- Fig. 1 shows diagrammatically portions of two boiler and superheater units of an installation equipped with superheater protection or steam circulating means according to one embodiment of the invention, the power medium employed in the energy converting apparatus of the steam circulating means of a unit being saturated steam drawn from another boiler or boilers of Vthe installation.

Fig. 2 illustrates diagrammatically another embodiment of` the invention in which steam which has passed through the superheater of a boiler or unit has its pressure increased and'is employed as the power medium in the energy converting apparatus of the steam circulating means of the unit.Y

Fig. 3 illustrates diagrammatically a further embodiment of the invention in which water from the boiler is employed as the power medium of the energy converting apparatus of the steam circulating means of the unit, and

Fig. 4 shows more or less diagrammatically the 'construction of the energy converting apparatus employed in steam circulating means according to the invention.

Referring rstly to Fig. 1, the two units of the installation there shown are marked A and B respectively, a portion only of the unit B being illustrated. Each unit comprises a boiler, a steam and water drum I of which is shown, and a superheater comprising elements 2 and inlet and outlet headers 3 and 4 respectively. The steam space of the drum I is connected by a pipe 5 to the inlet header 3 of the superheater and by a branch 6 controlled by a stop valve V'I to a, saturated steam range or ring main 8. The outlet header 4 of theY superheater is connected as usual by a pipe 9 controlled by a stop valve I0 to the superheated stream range of the installation which is not shown in the drawing. II indicates an energy converting apparatus, which will be described later, the general construction of which is shown in Fig. 4, and which comprises a steam chamber I2 connected by a pipe I3 equipped with a stop valve I4 to the pipe 9 receiving superheated steam from the header 4. A check valve I5 may be interposed between the chamber I2 and the stop valve I4. Entered in the steam chamber I2 of the energy converter is the outlet end portion of a converging tube or nozzle I6, the inlet end or larger end of the nozzle being connected by a pipe I1 equipped with an appropriate control valve I8 to the saturated steam range or ring main 8. Axially aligned with the converging nozzle IB is a diverging tube I9, this tube being bell-mouthed or flared at its entrance more or less as shown at I9a in Fig. 4. The iiared entry end of the diverging tube I9 is shown spaced from the'outlet end of the nozzle I6 to provide for open communication between such inlet end of the tube I9 and the steam space or chamber I2 of the energy converter; the relative dispositions of the outlet end of the nozzle I6 and the inlet end of the tube I9 may vary provided the arrangement is such that the nozzle I6 delivers into the throat of the tube I9 and said throat is in open communication with the chamber I2. The outlet or delivery end of the diverging tube I9 is con* nected by a pipe 29 to the boilerdrum I such pipe 20 preferably discharging into the drum below the water level therein. The return line or pipe 20 would be equipped with a check valve 2l to prevent water from the drum iiowing into the energy converter when the boiler is on load and the energy converter idle. A stop valve may also be provided if desired.

Assuming that pressure is being raised in the unit A and that the unit B is on load, the valves 'I and I0 of unit A will be closed and the valve I4 of unit A and valve 1 of unit B will be open as also will be the valve I8 of unit A. Saturated steam delivered by the boiler of unit B into range 8 will flow by way of pipe I 'I and valve I8 into the energy converter II of unit A. It will be appreciated that such saturated steam is at relatively high pressure and the pressure energy of such steam is converted in the nozzle I6 to velocity energy. The steam enters the throat of the diverging tube I9 at high velocity and at a pressure less than thatin boiler drum I and induces a ow of steam through the superheater into chamber I2 of the energy converter. The divergent tube I9 converts the velocity energy of the high velocity steam from the nozzle I6 intov pressure energy, and raises its pressure above that existing in the boiler drum I of boiler A. The steam delivered by the divergent tube I9 into the pipe 20 discharges into the boiler, preferably below the water level therein as already mentioned. This steam comprises the saturated steam supplied to the energy Vconverter and the steam which has owed through the superheater 2 and has performed protective duty therein. Thus, according to the invention, the steam from the boiler of a unit is utilized to protect the superheater of the unit during pressure raising and is returned to the said boiler. The steam which has iiowed through the superheater 2 is at relatively high temperature and by delivering it into the water space of the boiler, together with the relatively small quantity of saturated steam used in the energy converter, the raising of pressure in the boiler will be accelerated.

Referring now to Fig. 2, in the embodiment of the invention therein illustrated, instead of supplying to the converging nozzle I6 of the energy converter saturated steam from another unit of the installation, a relatively small percentage (for instance, 10%) of steam which has passed through the superheater 2 is taken from the pipe I3 through a branch 22, by a steam pump 23 driven by any appropriate motive power, as for its example, by an electric motor. The pump 23 raises the steam it draws from the pipe I3 to a relatively high pressure andvdelivers it by a pipe I'Ia, to the energy converter II, where it operates to create a pressure drop across the superheater 2 and to return circulated steam to the boiler drum I in the manner already described with reference to the embodiment of the invention illustrated in Fig. 1. Further de scription of this embodiment of the invention is not considered necessary, but it may be mentioned that the arrangement according to Fig. 2 is such that it may be applied to an independent boiler and superheater unit or to respective units comprised in an installation. It will also be appreciated that only a small amount of power is required to operate the pump 23 in order to raise the relatively small quantity of steam to the high pressure needed to render the energy converter operative to insure an efficient circulation of steam through the superheater.

In the embodiment of the invention shown in Fig. 3, instead of steam being employed as the power medium in the energy converter, water at high pressure is supplied toI said energy converter. As shown in Fig. 3, a water line 24 is taken from the water space of the boiler rum I to the inlet of the converging nozzle of the energy converter II and a pump 25 is included in the water line 24, a check valve 2B being interposed between the pump and the boiler. The pump 25 is driven by a small electric motor or other appropriate motive means. As in the embodiments of the invention shown in Figs. l and 2, the energy converter discharges through a return line into the water space of the drum I. In the embodiment of the invention under description, it will be appreciated that steam which has passed through the superheater 2 and is drawn through pipe I3 into the steam chamber of the energy converter by the high pressure water delivered into the divergent tube or" the energy converter will be returned into the boiler with the said water by way of the pipe El). If desired, instead of drawing the small quantity of water for the energy converter from the boiler drum I, it may be drawn from the feed line of the boiler. It will be appreciated that a boiler and superheater with steam circulating means according to Fig. 3, constitutes a self-contained unit, in that steam from another boiler is not required to render the circulating means operative as in the case of the embodiment of the invention shown in Fig. 1, and the circulating means according to Fig. 3, therefore, may be applied to a single isolated boiler and superheater equally as well as to one of a number of boilers with superheaters in a boiler house.

If desired, means may be provided to regulate the flow through the energy converter of the aqueous fluid (steam or water) used as the power medium therein, in order to produce the required ilow of steam through the superheater to be cooled over the range of boiler pressure from atmosphere to main range pressure. For example, means may be provided for maintaining a difference of constant or other predetermined value between the pressure in the boiler and that at the entrance to the energy converter for circulating steam, by automatically regulating the opening of the valve I8 in Fig. l or automatically regulating the operation of the pumps 23, 25, Figs. 2 and 3, to thereby control the pressure of aqueous fluid supplied to the converging nozzle I6 of the energy converting apparatus, according to the pressure obtaining in the boiler of the unit in which pressure is being raised. For example, as shown in Fig. 1, a pressure line 30 is connected to the steam drum I and to a bellows 3l or other suitable apparatus adapted to regulate the opening of valve I8 in accordance with the pressure existing in the boiler. The steam pump 23 in Fig. 2 and the water pump 25 in Fig. 3 are likewise associated with devices 3i responsive to steam pressure for regulating their speed of operation.

The apparatus according to the present invention is small and cheap, and is such that a relatively large quantity of steam may be circulated through a superheater by means of a small quantity of high pressure steam or water, whereby efiective cooling of the superheater will be obtained with a small consumption of power from a source other than the boiler with which such superheater is associated.

What I claim is:

l. The method of protecting a steam superheater of a boiler from overheating during pressure raising, which consists in iiowing through the superheater and returning to the boiler steam generated in the boiler, the ilow of steam from and its return to the boiler being effected by flowing into the boiler through an appropriate apparatus connected to the superheater outlet and to the boiler aqueous fluid supplied to such apparatus at a pressure higher than the then existing boiler pressure, the aqueous fluid in lio-wing through such apparatus inducing the flow of steam through the superheater and thereafter carrying such steam with it into the boiler.

2. The method of protecting a steam superheater of a boiler from overheating during pressure raising, which consists in supplying to an energy converting apparatus aqueous fluid at a pressure above that obtaining in the boiler, changing in said apparatus the pressure energy of the aqueous uid to velocity energy, utilizing the high velocity fluid so produced to induce a flow of steam from the boiler through the superheater thereof to said apparatus, reconverting in said apparatus the velocity energy of the aqueous iiuid to pressure energy to restore said iiuid to a pressure above that obtaining in the boiler, and delivering into the boiler said aqueous fluid together with the steam from the superheater carried forwardly from said apparatus by said fluid.

3. The method of protecting a steam superheater of a boiler from overheating during pressure raising as claimed in claim 2, characterized in that the aqueous fluid under pressure supplied to the energy converter is saturated steam from another boiler or boilers on load.

4. In a steam generating and superheating installation, the combination with a boiler and its superheater, of means for inducing a ow of steam from the boiler through the superheater during pressure raising and returning such steam to the boiler comprising an energy converting apparatus having a steam chamber connected by a conduit to the outlet from the superheater so as to receive steam therefrom, a converging nozzle in said chamber to the entry end of which nozzle is supplied aqueous fluid at a pressure above the boiler pressure, and a diverging tube axially aligned with said nozzle and having its inlet end bell-mouthed and open to said chamber and into which end of said tube said aqueous fluid is directed by said nozzle, a duct connecting the delivery end of sai-d diverging tube to the boiler, check valves in said conduit and duct respectively toI prevent fluid flow in the reverse direction therethrough when the boiler is on load, and means for regulating the pressure of the aqueous fluid supplied to the energy converter to maintain constant the diiference between the pressure in the boiler and that at the entrance for steam from the superheater to the said chamber.

5. A steam generating and superheating installation comprising a plurality of boiler and superheater units each equipped with means for protecting its superheater during pressure raising in its boiler as claime-d in claim 4, wherein the steam space of each boiler is connected through a stop valve to a saturated steam line and the entry end of the converging nozzle of the energy converter is connected to said line through a pressure regulating valve to receive saturated steamrtherefrom at an appropriate pressure.

6. A steam generating and superheating installation as claimed in claim 4, wherein a branch from the conduit leading steam 'from the superheater to the steam chamber of the energy converter is connected to the intake cfa steam pump driven by an electric motor or other appropriate motive means, and the delivery of said pump is connected to the entry end of the converging nozzle of said energy converter, whereby there is supplied to the said nozzle, as the aqueous fluid under pressure, steam which has passed through the superheater.

7. A steam generating and superheating installation as claimed in claim 4, wherein a local water line connects th'e water space of the boiler with the entry end of the converging nozzle of the energy converter and a pump is provided in said line to raise the pressure of the water above the boiler pressure, a check valve being inter-A posed in said line between the boiler and the Dump- 8. The method of protecting a steam superheater of a boiler from overheating during pressure raising which consists in drawing Water from the boiler, supplying said Water to an energy converting apparatus at a pressure above that existing in the boiler, changing in said apparatus the pressure energy of said water to Velocity energy, utilizing the high velocity Water so produced to induce a iiow of steam from the boiler through the superheater thereof to said apparatus, reconverting in said apparatus the ve-n locity energy of said water to pressure energy to restore said Water toy a pressure above that existing in the boiler, and delivering into the boiler said water together with the steam from the superheater carried forwardly from said apparatus thereby. Y

9. In the method of protecting a steam superheater from overheating during pressure raising as claimed in claim 2, wherein the aqueous uid under pressure supplied to the energy converter is steam generated in the boiler, the step of increasing the pressure of said steam before supplying it to said energy converter.

10. In a boiler having a steam and Water drum and a superheater connected to receive steam therefrom; a conduit connecting the outlet end of the superheater with said drum; an energy converter so placed in said conduit as to induce a ow of steam generated in the boiler through said superheater to protect the latter when pressure is being raised in said boiler; and means for supplying steam generated in the boiler to said converter at a pressure higher than exists in said boiler for actuating the latter to induce said iiow of steam through the superheater and return it to said drum.

11. In a boiler having a steam and water drum and a superheater connected to receive steam therefrom; a, conduit connecting the outlet end of the superheater with said drum; an energy converter so placed in said conduit as to induce a ilow of steam generated in the boiler through said superheater to protect the latter When pressure is being raised in said boiler; and means for supplying water to said converter at a pressure higher than exists in the boiler for actuating said converter to induce said steam iiow through said superheater and return said steam and water to said drum.

12. In a boiler having a steam and water drum and a superheater connected to receive steam therefrom; a conduit connecting the outlet end of the superheater with said drum; an energy converter so placed in said conduit as to induce a ilow of steam generated in the boiler through' said superheater to protect the latter when pressure is being raised in said boiler; a conduit and pump therein for withdrawing water from said drum and supplying it to said converter ata pressure lighter than exists in said boiler for actuating said converter to induce said steam flow through said superheater and return said steam and water to said drum. Y

JOHN EDWIN WOOD.

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