US3303827A - Method and apparatus for removing steam peaks from a steam boiler which utilizes cyclically produced waste heat, preferably the waste heat from converters blown by oxygen - Google Patents

Description

Feb 1967 R. KEMMETMULLER ETAL 3,303,

METHOD AND APPARATUS FOR REMOVING STEAM PEAKS FROM A STEAM BOILER WHICH UTILIZES CYCLICALLY PRODUCED WASTE HEAT, PREFERABLY THE WASTE HEAT FROM CONVERTERS BLOWN BY OXYGEN Original Filed Jan. 15, 1962 2 Sheets-Sheet 1 R. KEMMETMULLER ETAL 3,303,827 METHOD AND APPARATUS FOR REMOVING STEAM PEAKS FROM A STEAM Feb. 14, 1967 BOILER WHICH UTILIZES CYCLICALLY PRODUCED WASTE HEAT PREFERABLY THE WASTE HEAT FROM CONVERTERS BLOWN BY OXYGEN Original Filed. Jan. 15, 1962 26 3 2 Sheets-Sheet 2 I P 1 22 Fig.4

United States Patent 3,303,827 METHOD AND APPARATUS FDR REMUVING STEAM PEAKS FROM A STEAM BUHLER WHICH UTILIZES CYCLICAELY PRUDUQED WASTE HEAT, PREFERABLY THE WASTE HEAT FROM CGNVERTERS BLOWN BY OXYGEN Roland Kemmetmuller, Vienna, Demeter Karl Markow,

Graz, and ingo Pascher, Graz-Kroisbach, Austria, assignors to Waagner-Biro Aktiengeselischait, Vienna, Austria, a firm of Austria Original application Jan. 15, 1962, Ser. No. 166,039, now Patent No. 3,234,920, dated Feb. 15, 1966. Divided and this application Dec. 16, 1965, Ser. No. 514,297 Claims priority, application Austria, Jan. 20, 1961, A 489/61, A 491/61, A 492/61 Claims. (Cl. 1227) The present application is a divisional application of the application filed January 15, 1962, with the Serial Number 166,039, now Patent No. 3,234,920.

In intermittently operated steel converters with steam generating plants connected in series therewith it is difiicult to place in a steam net the steam peaks obtained approximately every forty or sixty minutes during operation of the converter. There are different measures known and suggested for partially or completely equalizing these steam peaks.

It is for instance known to turn on an additional heating in the time between two blowing periods. This additional heating results in a higher average steam production over the period; thus the surplus amount with respect to the average and therefore also the accumulator (reservoir) volume become smaller. A compensation is gained for instance through different steam accumulator circuitarrangements, that is by the installation of Ruths-accumulators which can be variously connected with respect to the boiler. From the gradient and the volume of the accumulator results the amount of accumulated steam. For a complete compensation of such steam peaks a relatively large accumulator volume and a high design-pressure must be provided. A circuit-arrangement is also known wherein the steam of the accumulators is passed once more to the boiler superheater or where the superheating temperature is gained only in a separately heated superheater. Certain equivalent circuits are also known which permit to reduce the feed pump output; this can be attained either by considerably enlarging the boiler drum which then together with the entire pipe system of the boiler functions as an accumulator itself or by connecting the boiler drum and one accumulator drum in parallel, in order to enlarge the water volume and thus the accumulator capacity.

There are known further circuit-arrangements and processes wherein a part of the steam taken off the accumulator is used for preheating the boiler feed-water by means of reduction stations.

The use of enlarged accumulator contents of the drum or shunted accumulators and drums has the disadvantage that the pressure in the boiler system varies corresponding to the accumulator pressure. The accumulator circuitarrangements with mere Ruths-accumulators with a pressure control at the inlet side and at the outlet side at constant boiler pressure have the disadvantage that for mastering the steam peaks large accumulator volumes are required whereby accumulator and boiler must be constructed for the high pressure side.

The invention therefore is based on the idea of keeping the boiler pressures constant, of either keeping also the feed-water temperature at the boiler inlet as constant as possible or of controlling the feed-water temperature, and nevertheless to be able to operate the entire system with a low pressure, that is with a pressure which corresponds in ICC an accumulator circuitarrangement with Ruths-accumulators to the outlet pressure, and thus to save not only substantial investment costs for boiler and accumulator but also operating costs by a substantial reduction of the necessary feed pump output. According to the invention this is obtained in that during the period of the cycle in which waste heat is produced the surplus-steam-amount is led to an accumulator and condensed therein by which the feed water in the accumulator is heated and that during the period of the cycle in which waste heat is produced as well as during the period of the cycle in which no waste heat is produced the water heated in the accumulator is mixed with cold feed water delivered by the feed water pump so that any desired mixed temperature for the feedwater fed to the steam boiler may be obtained.

In the drawing the object of the invention is shown by way of example. FIGS. 1 to 3 show circuit diagrams of plants according to the invention at which steam produced in the boiler as far as it is surplus is mixed with boiler feed water in the accumulator. According to FIG. 1 saturated steam is produced in the boiler and delivered partly to the consumers, partly to the accumulator. According to FIG. 2 superheated steam is produced in the boiler and delivered partly to the consumers, partly to the accumulator. In FIG. 3 only the amount of steam led to the consumers is superheated, While the steam led to the accumulator is saturated steam.

FIGS. 4 and 5 show circuit diagrams of plants according to the invention at which the steam fed into the accumulator is not mixed with the boiled feed water in the accumulator, but transfers its heat to the boiler feed water by heat exchange means. According to FIG. 4 the heat is transferred directly to the boiler feed water, according to FIG. 5 by means of an intermediate heat carrier.

As may be learned from FIG. 1 the cyclically produced waste heat of a converter 28 is used in a boiler 1 with a boiler drum 3 and a feed-water preheater 2 for producing steam which is intended to be fed to the consumers through a line 13 in a continuous supply. However, since the blowing time of the converter is short; an additional heating means 33 is provided for heating the boiler during the blowing intervals. In order to be able to keep additional heating means 33 as small as possible the surplus amount of peak steam is passed during the blowing time, that is, during the time in which waste heat is produced, to a feed-water container or heat exchanger 4 through a steam conduit 1 where it is condensed and forms a hot water supply 17 over which a steam cushion 19 is maintained.

A branch line 7 of the feed-pump pressure line is connected to the lower part of the vertically arranged feedwater container 4 through a distributing throttle 24.

The feed pump It delivers cold teed-Water from the feed-water inlet line 5 partly through the branch line 7 to the lower part 18 of the teed-water container 4, and partly through the main line 6 to a mixer 9, to which hot water from the upper part 17 of the feed-Water container 4 is admixed, in proportions corresponding to the desired temperature in the mixing line 8. Hot water is taken off the upper part 17 of the feed-water container 4 through a conduit having an inlet end held a fixed distance above a floating piston 25 which separates the cold water volume 18 from the hot water and this conduit is connected to the outlet pipe 7a through a flexible connection 23. The water mixed in the mixer 9 is fed through line 8 through an economiser 2 into the boiler drum 3 to thus supply the boiler drum with feed water of predetermined temperature.

The temperature of the mixture is controlled from the boiler drum 3 through control lines 22 of known construction so that the boiler is operated with temperature as constant as possible during the interval between blowing periods where the additional heating means 33 is turned on as well as during the blowing period.

A circulating line 15 with a circulating pump 12 serves for revolving the water contents in the feed-water container or heat exchanger 4 during the period of the cycle in which Waste heat is produced, that is to circulate and mix the cold water accumulated in the heat exchanger during the period of the cycle in which no waste heat is produced with the hot water therein so as to increase the amount of hot water in the heat exchanger at the end of the period of the cycle in which waste heat is produced to a maximum. The control of the pump is effected at constant steam supply automatically by way of a controlling member 21 by steam pressure or by the steam supply to the container. Cold feed water is preferably fed into the heat exchanger 4 during the period in which the cold water therein is circulated and mixed with the heated water. The amount of heated water and cold water to be mixed and fed into the boiler 3 may be regulated in dependence on the water level in the boiler. The boiler is a forced-flow boiler with four circulating pumps 11 and thus is operated with a constant or a two-stage feed-Water temperature.

In FIG. 2 substantially the same plant is shown; the dif ference is that a superheater 30 is provided in the boiler which is passed by the entire quantity of steam produced in the boiler.

In the circuit arrangement shown in FIG. 3, however, the superheater is passed only by that part of the steam produced which is delivered to the consumers at 13, whereas the steam peak produced during the blowing period is directly delivered as saturated steam to the feed-Water container 4.

As may be learned from FIG. 4 the heated evaporator surfaces 1 of the boiler are connected with the boiler drum 3 for a forced-flow; for safetys sake two circulating pumps 11 are provided. The saturated steam produced is passed to the consumers through a steam supply line 13 and the steam valve 26 in line 13 is controlled by a measuring device 27. The surplus peak steam obtained during the blowing time of the converter, not shown, is passed through the line 14 to a feed-water container or heat exchanger 4; there said steam transfers its heat as it passes through the steam conduit portion 16 to the water content of the feed-water container 4 and subsequently condenses in the feed-water stock container 4a. Thereby also the remaining heat is extracted. From the feed-water stock container 4:: the relatively cold feed-water is drawn off by the feed pumps 10, which for safetys sake are also provided in duplicate, and is passed through the feedwater supply line 5 either to the main line 6 so that during 1 the period of the cycle in which waste heat is produced cold feed water may be fed directly into the boiler, and/or to the branch line 7 to which the feed-water container 4 is connected. The water from the branch line 7 is passed to the lower part of the vertically arranged feed-water container 4 wherein for a more equal distribution of the water over the whole cross section of the container throttling members 24 are arranged. In the feed-water container 4 the feed-water is heated by the peak-steam passing through the conduit 16; thus during the blowing time of the converter the hot water volume 17 accumulating in the upper part of the feed-water container increases, whereas the cold water portion 18 in the lower part decreases correspondingly as the boiler during this time is fed with cold feed-water merely or mainly through the main line 6.

After the blowing time of the converter is over, feeding through the main line 6 is throttled and feeding is effected mainly from the upper part of the feed-water container 4 through the line 7a. Thus, already preheated feedwater is passed to the boiler which is operated only with a small additional heating means and thus is enabled to maintain the delivery of steam to the consumers. Of course, no surplus steam is now available for the heat exchanger 16; therefore the warm water stock 17 in the feedwater container decreases, whereas the cold water volume 18 is increased to the same extent by the cold water fed thereinto. The control of these operations is effected by valves 22 and 21 which are installed in the steam line 14 and in the lines 7a and 6 and which are automatically controlled in a manner known per se in dependence on the amount of surplus steam available.

In the circuit arrangement according to FIG. 5 the main line 6 is not fed into the boiler drum 3 but into the fall pipe of the boiler which is operated with natural fiow or forced flow. The container 4 here is filled with a liquid 29 having a high boiling point as for instance glycerin, oil, mercury, or the like; the heat exchange is effected by the liquid surrounding the heat exchanger 16, through which the steam from steam conduit 14 flows in one direction, while the water from conduit 7 to conduit 7a flows in counter-current to the steam flow.

The heat retaining liquid 20 may also be revolved through a container circulating line 15 having circulating pumps 12.

This circuit-arrangement has the advantage that due to the specific liquid used small pressures are prevailing in the container 4; therefore the container can be made at correspondingly low costs. I

It will be understood that each of the elements described above, or two or more together, may also a useful application in other types of steam boilers differing from the types described above.

While the invention has been illustrated and described as embodied in a steam boiler which uses cyclically produced waste heat, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 4

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the stand= point of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equiv alence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A method of equalizing steam peaks in a waste gas steam boiler using cyclically produced waste heat com-- prising the steps of feeding, during the period of the cycle in which waste heat is produced, the surplus steam produced in said boiler into heat exchanger means; sup'= plying cold feed water to said heat exchanger means so as to at least partly condense the surplus steam while heating the cold feed water; feeding to said boiler, dur'- ing the period of the cycle in which waste heat is pro= duced as well as during the period in which no Waste heat is produced, heated feed water from said heat ex= change means mixed with cold feed water in such pro= portion as to supply the boiler with feed water of pre-' determined temperature; and heating the steam boiler during the period of the cycle in which no waste heat is produced by additional heating means.

2. A method as set forth in claim 1, wherein said heated feed water from said heat exchanger means and the cold feed water is mixed outside said boiler, and wherein the temperature of the mixed feed water is kept substantally constant during the whole cycle.

3. A method as set forth in claim 1, wherein said heated water from said heat exchange means and the cold feed water is mixed outside said boiler, and wherein the temperature of the mixed feed water is regulated between a maximum and a minimum temperature higher than the temperature of the cold feed water.

4. A method as set forth in claim 1, wherein, during the period of the cycle in which no waste heat is produced, cold water is fed into said heat exchanger means :9 and simultaneously heated water therein discharged therefrom so as to increase during said period the portion of cold water in said heat exchanger means, and wherein the heated water taken from said heat exchange means is mixed outside said boiler with cold feed water and the mixture then fed into said boiler.

5. A method as set forth in claim 1, and including the additional step of circulating and mixing, during the period of the cycle in which waste heat is produced, the cold water, accumulated in said heat exchanger means during the period of the cycle in which no waste heat is produced, with the hot water therein in proportion to the amount of surplus steam fed into the heat exchanger means so as to increase the amount of hot water in the heat exchanger means at the end of the period of the cycle in which waste heat is produced to a maximum.

6. A method as set forth in claim 5, and including the step of feeding cold water into said heat exchanger means during the period in which the cold water therein is circulated and mixed with the heated water.

7. A method as set forth in claim 6, wherein the heated water from the heat exchanger means and cold feed water is mixed outside the boiler, and including the step of automatically regulating the amount of heated water and cold water to be mixed and fed into the boiler in dependence on the water level in the boiler.

8. A method as set forth in claim 1, wherein the amount of heated water and the amount of cold water fed into the boiler is regulated in such a manner that, during the period of the cycle at which a maximum waste heat is available, the temperature of the mixed feed wa ter is held lower than during the period at which a minimum or no waste is available.

9. A method as set forth in claim 1, wherein, during the period of the cycle in which waste heat is produced, cold feed water is fed directly into the boiler.

10. A method as set forth in claim 1, wherein, during the period of the cycle in which no waste heat is produced and the boiler is heated by additional heating means, cold water is fed into the heat exchanger means and hot water located therein is displaced into the boiler so as to increase during said period the amount of cold water in said heat exchanger means to the maximum.

11. In a steam boiler for utilizing cyclically produced waste heat, said steam boiler including a boiler drum adapted to be filled to a predetermined level with water, in combination, heat exchanger means; steam conduit means providing communication between said boiler drum above the level of water therein and said heat exchanger means for feeding steam into the latter; a cold feed water supply; first water conduit means providing, on the one hand, communication between said cold feed water supply and said steam boiler and, on the other hand, communication between said cold feed water supply and said heat exchanger means for feeding cold water into said boiler and into said heat exchanger means, respectively, so that the cold water fed into the latter is heated up by the steam fed thereinto by said steam conduit means; second water conduit means providing communication between said heat exchanger means and said steam boiler for feeding water heated up in said heat exchanger means into said boiler; means for selectively controlling flow of cold water from said cold feed water supply through said first water conduit means into said boiler and flow of heated feed water from said heat exchanger means into said boiler so that at the end of the period of the cycle in which waste heat is produced the amount of heated water in said heat exchanger means is at a maximum and at the end of the period of the cycle in which no waste heat is produced the amount of cold water in said heat exchanger means is at a maximum; and additional heating means for heating said boiler during the period of the cycle in which no waste heat is produced.

12. In a steam boiler as set forth inclaim 11, wherein said heat exchanger means is an upright displacement type feed water accumulator and wherein said steam conduit means communicates with the upper end of said accumulator and said first water conduit means communicates with the lower end thereof.

13. In a steam boiler as set forth in claim 12, and including means for maintaining an accumulation of steam at the upper end of said accumulator above the level of water therein.

14. In a steam boiler as set forth in claim 13, and in cluding means for pumping cold water from the lower end of the accumulator into the upper end thereof so as to circulate the water in said accumulator.

15. In a steam boiler as set forth in claim 14, and including means for automatically controlling the circulation of water in said accumulator in dependence on the pressure of steam in said steam boiler.

16. In a steam boiler as set forth in claim 14, and including means for automatically controlling the circulation of water in said accumulator in dependence on the amount of steam delivered by said steam boiler.

17. In a steam boiler as set forth in claim 13, wherein said means for maintaining an accumulation of steam in the upper end of said accumulator include a floating piston said accumulator separating the hot from the cold water therein, and a discharge conduit having a flexible portion below said floating piston and communicating at one end thereof with said second water conduit means, said discharge conduit having an inlet end held a fixed distance above said piston.

18. In a steam boiler as set forth in claim 11, wherein said heat exchanger means is an upright displacement type feed water accumulator wherein said steam conduit means extends with a portion thereof through said displacement type feed water accumulator so that the steam passing through said portion heats the cold feed water fed into said accumulator, and wherein said first water conduit means communicates with the lower end of said accumulator.

19. In a steam boiler as set forth in claim 18, wherein said cold feed water supply includes a water container and wherein said steam conduit means extends with an end downstream of said accumulator into said water container so that steam passing through said steam conduit means into said water container will heat the water there in, said first water conduit means communicates at one end thereof with said water container.

2%). In a steam boiler as set forth in claim 18, and including throttling means in a lower portion of said accumulator for assuring spreading of cold water fed thereinto through the whole cross-section of said accumulator.

21. In a steam boiler as set forth in claim 18, wherein said means for selectively controlling fiow of cold water from said cold feed water supply through said first water conduit means into said boiler and flow of heated feed water from said accumulator into said boiler are operatively connected to said steam conduit means for automatically regulating flow of cold and heated water into said boiler in dependence on the amount of steam flowing through said steam conduit means.

22. In a steam boiler as set forth in claim 11, wherein said heat exchanger means comprises a container adapted to be filled with liquid having a high boiling point, wherein said steam condiut means extends with a portion thereof through said container in heat exchange with the liquid therein, and wherein said first water conduit means includes a branch conduit extending with a portion thereof through said container in heat exchange with the liquid therein, said branch conduit communicating at one end thereof with said cold water supply and at the other end thereof with said second water conduit means communicating with said steam boiler.

23. In a steam boiler as set forth in claim 22, wherein said portions of said steam conduit and said branch conduit are arranged in said container and respectively connected to said cold Water supply and said boiler so that the steam flows through said portion of said steam conduit means in said container in counter-current to the flow of cold Water through said portion of said branch conduit in said container.

24. In a steam boiler as set forth in claim 22, and including means for circulating the liquid in said container.

25. In a steam boiler as set forth in claim 24, wherein said container is an upright container and wherein said liquid circulating means include pump means for pumping liquid from the lower end of the container into the upper end thereof.

References Cited by the Examiner UNITED STATES PATENTS 1,265,020 5/1918 Zublin 12235 1,659,836 2/1928 Ruths 12232 2,550,822 5/ 1951 Kielland 122-35 FOREIGN PATENTS 210,445 8/ 1960 Austria.

425,987 3/ 1926 Germany.

549,113 4/ 1932 Germany.

832,762 2/1952 Germany.

214,965 12/1924 Great Britain.

335,812 10/1930 Great Britain.

285,178 5/1931 Italy.

CHARLES J. MYHRE, Primary Examiner".

Claims (1)

1. A METHOD OF EQUALIZING STEAM PEAKS IN A WASTE GAS STEAM BOILER USING CYCLICALLY PRODUCED WASTE HEAT COMPRISING THE STEPS OF FEEDING, DURING THE PERIOD OF THE CYCLE IN WHICH WASTE HEAT IS PRODUCED, THE SURPLUS STEAM PRODUCED IN SAID BOILER INTO HEAT EXCHANGER MEANS; SUPPLYING COLD FEED WATER TO SAID HEAT EXCHANGER MEANS SO AS TO AT LEAST PARTLY CONDENSE THE SURPLUS STEAM WHILE HEATING THE COLD FEED WATER; FEEDING TO SAID BOILER, DURING THE PERIOD OF THE CYCLE IN WHICH WASTE HEAT IS PRODUCED AS WELL AS DURING THE PERIOD IN WHICH NO WASTE HEAT IS PRODUCED, HEATED FEED WATER FROM SAID HEAT EXCHANGE MEANS MIXED WITH COLD FEED WATER IN SUCH PROPORTION AS TO SUPPLY THE BOILER WITH FEED WATER OF PREDETERMINED TEMPERATURE; AND HEATING THE STEAM BOILER DURING THE PERIOD OF THE CYCLE IN WHICH NO WASTE HEAT IS PRODUCED BY ADDITIONAL HEATING MEANS.

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