US1314140A - Steam-boiler economizer and method of operating the same - Google Patents

Description

n. s. JACOBUS.

smm some EcowomlzER AND mmon 0F OPERATING ms SAME.

APPLICATION FILED D EC-BI 1914- 1 ,3 1 4, 1 4O Patented Aug. 26, 1919.

3 SHEETS-SHEET 1.

MNESSE M/I/EIVTOR r/ A Tram/Hf D. S. JACOBUS.

STEAM BOILER ECONOMIZER AND METHOD OF OPERATING THE SAME.

APPLICATION FILED DEC-8,1914.

Patented Aug. 26, 1919.

3 SHEETSSHEET 2.

.HEHE g3 IAN/EN T 0/? D. S. JACOBUS.

STEAM BOILER ECONOMIZER AND METHOD OF OPERATING THE SAME.

APPLICATION FILED DEC-8.1914.

1,3 1 4, 1 4O Patented Aug. 26, 1919 3 SHEETSSHEET 3.

(2 W d 41 W 6 MWWC ,QiiiQd/WBM 14in! A TTORNEYH S PATE OFFIGE.

DAVID S. ACOBU S, 0F JERSEY CITY, NEW JERSEY, ASSIGNOR TO THE BABCOCK & WILCOX COMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

Specification of Letters Patent.

Patented Aug. 26, 1919.

Application filed December 8, 1914. Serial No. 876,010.

To all whom it may concern:

Be it known that I, DAVID S. JAoonUs, a citizen of the United States, residing in J ersey City, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Steam-Boiler Economizers and Methods of Operating the Same, of which the following is a specification.

Corrosion or pitting in the interior of a boiler is due to elements in the water that oxidize or otherwise afi'ect the-iron. This is often prevented or minimized by the addition to the water of a neutralizing reagent, such as carbonate of soda or lime, the reagent being added until it accumulates in the boiler to a point where the amount per gallon of water in the boiler, or the degree *of concentration, is such as to effect the desired result. After the reagent is added it remains in the boiler as it is not evaporated in producing steam and the amount of the reagent that must be supplied after the first reagent is added will be only that required to make up for any chemical action, or for the amount that is lost in blowing down the boiler. The reagent may be added at intervals to the boiler, say once per day, or it may be added continuously to the feed water. If added continuously to the feed water the amount per gallon of feed water may be less than that needed to prevent the corrosion, and the reagent may be allowed to concentrate in the boiler to the proper amount. For example, the feed water might be treated with two grains of the reagent per gallon which could be allowed to concentrate in the boiler to twenty grains per gallon, and the twenty grains per gallon might give good results where the two grains per gallon would not.

An economizer cannot be protected from interior corrosion by the addition of a reagent from time to time as in a boiler as the reagent would 'pass directly through the economizer with the water; again, should the reagent be added continuously to the feed water it cannot be made to concentrate in the economizer in the way that it does in a boiler. In the numerical example just given, if twenty grains were needed to prevent corrosion it would be necessary to treat the feed water with twenty grains of the reagent per gallon to properly protect the economizer, which would make the treatment more costly than for a boiler and require the boilerto be blown down at frequent intervals to avoid over-concentration of the contained water.

Distilled water from a condenser, or such water with only a small amount of raw or make-up water mingled with it, has been found to give trouble through corrosion; air and carbonic acid gas in the feed water add to or in some cases may be the sole cause of corrosion.

The tendency in modern power plant practice is toward large size boiler units and high overloads, and to maintain a high capacity the boiler must be kept clean on its interior, otherwise there will be tube difficulties. It is, therefore, of extreme importance that the boiler feed water shall be of a high degree of purity and to meet the present tendency the practice is to cut down the amount of make-up water, to avoid the formation of scale in the tubes, and to increase the amount from the hot well, the latter being distilled water coming from the condensers in the plant. But water of the desired purity for the boiler will cause trouble through corrosion of the economizer, particularly if it is one of wrought iron or wrought steel.

The purpose of the present invention is to prevent both internal and external corrosion of an economizer, and particularly in one of wrought iron or wrought steel, by returning a certain amount of water from the boiler to the inlet of the economizer. Again, means are provided whereby mud or other foreign elements in suspension may be removed from the interior of the boiler and whereby a filter for removing oil may be used to advantage.

By returning the Water from the boiler in which the reagent may be allowed to concentrate to any desired amount, a sufiicient quantity of the reagent may be mingled with the water entering the economizer to prevent internal corrosion without involving undue expense, as with the system proposed the only addition of a reagent is that necessary to make up for leakage, for any water that may be blown away from the boilers, and for any chemical reaction which may take place within the economizers and boilers. In mingling the hotter water from the boiler with the feed water 'to the econo mizer, the temperature of the feed water is raised, which eliminates trouble through exterior corrosion on account of the-sweating which occurs on the exterior surface of the economizer with cold feed water through the condensation of moisture contained. in the flue gases. 7 I

With the system proposed much more water is withdrawn from the interior of the boiler than in usual practice where the amount of water withdrawn is only that which is blown off for the removal of mud or sludge, or for preventing over-concentration, and by providing proper settlingchambers the mud or other suspended matter in the water which is drawn olf may be removed.

The invention is not, however, limited to it includes the return of a certain amount of boilers, or what is known as the make-up water, contains in itself the necessary elements to prevent corrosion no reagent need be added. Whether the make-up water is one which requires the addition of reagents or a water which carries the necessary elements to prevent corrosion, the present invention prevents or lessens the tendency to corrosion in the economizer. Thefollowing example will serve to make my meanin clear.' As sume that there is 10% of ma e-up water containing eight grains of material per gallon of a nature that will tend to stop the corrosion that occurs with distilled water from the condensers. The mixture of the make-up water with the distilled water from the condensers would contain 0.73 grains per gallon. If operated in the ordinary way the water passing through the economizer would contain 0.73 grains per gallon of the material that would tend to stop corrosion, whereas the water contained in the boiler might be concentrated so as to contain say 100 grains of the'same material per gallon; If now the boiler and economizer are operated in accordance with the present invention,

and one ound of water containing 100 grains per gallon is withdrawn from the boiler and mingled with five pounds of the water containing 0.73 grains per gallon, the material in the mingled water which would pass through the economizer would amount to about 17 grains per gallon, a larger amount than theioriginal, 0.73 grains, leading. to a lesser amount of interior corrosion.

Again assume that the one pound of water withdrawn from the boiler is at a temperature of 390 F. and is mingled with fivepounds of water at 80 F. The final temperature of the mixture'would be about 130 -F., which would be above that at which sweating would occur on the exterior surface of the economizer, and heatingthe water in the way described would obviate the exterior corrosion which occurs in economizers through such sweating. By practising the present invention, therefore, the grains of matter tending to reduce corrosion in the numerical case considered is increased more than twenty times over what would exist in ordinary practice and the temperature of the water entering the economizer is increased from 80 F. to about 130F., both of which results lead to lesser corrosion.

That the concentration of certain elements in the water contained in a boiler may be much higher than in the feed water is well known in the art, and is naturally caused through the elements remaining in the boiler while the pure water is evaporated.

The method herein described of protecting economizers against corrosion will be understood from the following description, taken in connection with the accompanying drawings, in which Figure 1 is a diagrammatic View, partly in vertical section and partly in elevation, of a plant for carrying out the proposed method; Fig. 2 vertical section of a tank which may be used in place of the feed water tank of 1; Fig. 3 a more or less diagrammatic view of a modified arrangement of the plant; and Fig. a diagrammatic plan view of a plant having two or more boilers with a single feed water tank. Similar -reference numerals indicate similar parts in the several views.

Referring to Fig. 1 the'numeral 1 designates the downtake ends of a bank of in clined generating tubes, 2 the steam and water drum, 3 the flue outlet for the gases, and 4 an economizer placed in the flue leading from the-boiler, the gases passing through the economizer, and thence to a stack. Conveniently located with relation to the economizer is a feed water tank 5 and filter 16 from which the water is drawn, through pipe 6 by a pump 7, and forced through pipe 8, against the boiler pressure, to the colder end or section of the economizer through which it flows to the steam and water drum by a connection 9 controlled by a valve 9-. The control may be by the valve 9 the valve 9 being left open, or by regu lating the speed of the pump 7. The water intank "5 is made up of the main supply from the hot well 10, orother source, entering through pump 11 and pipe 12, and from water led from the boiler and controlled in amount by a valve 14. The boilerwater is preferably drawn from a point in the b01161" .where the water will not be mingled with the entering feed water and may be taken either from the steam and water drum 2 through the valved connection 13, or from the mud drum 1' through thevalved connection 13 or from both at the same time. Upon entering the tank 5 the boiler water passes through a. coil 15 attached to pipe 13, or pipe 13 so as to conduct the boiler water beneath the water inthe tank and thus prevent loss through vaporization of the hot water. The water from the hot well which enters through pipe 12 may be at the temperature of approximately 90 F. Upon mingling this with the water from the boiler it may be brought to a temperature of approximately 120 F. which temperature is that often used for water fed to economizers to prevent sweating on the outside of the economizertubes. Heating the feed water in the tank 5 also serves to expel air or other gases which maybe contained therein, and this eliminates the corrosive effect of the air or gases so expelled. The present method, therefore, minimizes both internal and external corrosion in economizers used in connection with steam boilers. The degree of concentration of the water in the boiler may be. determined by the standard method of chemical titration or by measuring the density of the water.

Mingling the boiler water with the feed water is advantageous where there is oil in the feed water as the chemical reagent will act on the oil and make it easy to remove the same by filtration. In such case the oil will be removed in the filter 16 placed between the tank 5 and the economizer. The pipe 16', the upper end of which is bent upward inside the tank. as shown, serves as an overflow for the tank 5 in case the water is raised from the boiler as well as preventing corrosion in the economizer. The sediment which collects in tank 5 may be discharged through a valve or cock controlled pipe 17.

The make-up water is fed to the hot well through the valved connertion 10, or it may be fed into the mixing tank 5.. In case a chemical reagent is required this may be introduced along with the make-up water or it may be introduced directly into the tank 5 or the hot well 10.

In Fig. 2 I have shown a. tank 18 which may be used in place of the tank 5 of'Fig. 1.

The pipes 12, 13', 6 and 16 correspond in .function to the pipes 12, 13, 6 and 16', respectively, of Fig. 1. The pipe 12' conducts the water from the hot well to a sprayer by which it is delivered over a series of perforatedplates 19. A float 20 connected with valve 21, in pipe 12, will regulate flooded up to the point of overflow. To flood the tank the regulator valve 21 may be operated by hand, and when the water rises to the overflow point, determined by the height of partition 24, oil or other impurity on the surface of the water will flow into the overflow. The overflow also serves as a means of making sure that, the tank will not be flooded in case of failure of the inlet water valve to act. The mingled water from the hot well and from the boiler passes through a filter 25 at the bottom of the tank and into pipe 6' which runs to feed pump 7. Any air or gases expelled from the feed water is allowed to escape through the vent pipe 18'.

In Fig. 3 the economizer 34 is shown as located above the boiler 35, the path of the gases from the underfeed stoker 36, as indi water blown off from the boiler, at the regular blow-ofi' periods, enters the tank 38 through pipe 39. Tank 38 is vented to the atmosphere and the steam, which is disengaged from the hot water blown from the boiler, is allowed to escape through pipe 40, by which 4 it is conducted to some point where it is either wasted or utilized. The water from tank 39 is pumped by pump 41 through pipe 41 into a tank 42 where it is mingled with the water to be fed to the economizer. The main supply of water for the economizer is pumped from hot well 43 by a pum 44 and enters tank 42 near the upper part t hereof through pipe 44, and is made to flow downward over a series of perforated shelves 42 in order that it may be thoroughly mingled with the hotter water from tank 38. Tank 42 is provided with a relief valve 45, and also with a valved pipe 46 which may be connected to a dry vacuum pump to create a partial vacuum in tank 42,

if desired, for the more thorough removal of air and gases. The water from tank 42 is pumped by pump 47 through pipe 47 into and through the economizer 34 from which it passes through the valved feed pipe 48 into the boiler. Any mud which settles in the tank 38 may be removed through the gate valve 38. This can best be doneby washing out the tank 38 with a hose with the valve 38 open. In some cases the tank 42 will be provided with the blow-ofl connection 42 for the removal of any mud that may collect in it, in which case the connee tion to the pump 47 would be taken from a point above the bottom as shown. The make-up water may be added either at the hot well 43, the tank 38 or the mixing tank 42. In case a chemical reagent is required z In Fig. 4 I have shown diagrammatically the pipe connections and general arrangement when two or more boilers and econopump mizers are used in connection with a single mixing tank. In this figure two boilers are indicated by the numeral 1, and an economizer for each boiler 'by the numeral 4, and

in general I have used the same reference numerals to indicate similar parts of the-arrangement for the two boilers. The feed water from the hot well 10 is forced to 'the top of the mixing tank, 18 by means of 11. The water from the interior of the boilers enters a common pipe 49, through throttle valves in branches 49 and is delivered to the tank 18. Meters 49'? may be usedto advantage to indicate the amount of water flowing from each boiler and to assist in the adjustment of the valyes in the branches 49. From the tank 10 the mingled water is conducted by pipe 6 to the feed pump 7 ,which delivers it into a common pipe 50, from which it is distributed through ranches 51, having adjusting valves 51, to the economizers 4. From the latter the water passes through pipes 52, through valves 52 to branches which deliver it to the steam and water drums of the boiler, these branches having ordinary check valves 52 The pipes 49 and 50 are shown as openended to indicate that they may be used for more-than the two boilers shown. The mixing tank 18is provided with a relief valve 18, a connection 18 for the removal of theair or gas discharged from the water, and

with a blow-ofi' connection 18 for the re"- moval of any mud or sediment that may be deposited from the water. The make-up water may be introduced either in the hot well 10, or the mixing tank 18. Where a chemical reagent is required it may be introduced along with the make-up water or by any other means.

The fans 53 draw the gases through the economizers 4 and discharge them into the uptakes 54. The fans are driven by any suitable motor.

In operating two or more boilers in accordance with the arrangement of Fig. 4, care must be exercised to maintain the amount of concentration in the boilers at about the same point, for should a materially lesser amount of water, in proportion to the water'evaporated, be returned from the interior of one of the boilers to the common tank in which the boiler water is mingled with the feed water from the hot well, the water in the boiler from which the lesser amount of water is drawn would soon reach a higher degree of concentration than in the other boilers.

. diagrammatic.

and ordinary pipe connections used in their place. Where a chemical reagent isnecessary it is preferably introduced along with the'make-up water, in which case the amount of concentration in each of the boilers may be regulated by blowing off more or less Should a boiler be water from theboiler. accidentally blown down to an extent that causes the concentration of the contained water to be too low, a certain amount of the reagent in solution may be pumped directly into the boiler by hand or by other means.

As has been stated, the drawings are Certain common and wellknown features such as safety valves for the economlzers have not been shown in order to emphasize the features which apply more particularly to the invention. Common and well-known means for regulating the supply of make-up water and of maintaining the proper levels of water in the hot wells may be used, and the same statement applies to regulating the water levels in the mixing tanks in the cases not shown.

By the word pressure in some of the claims,,as applied to the mingled waterin tank 42, I mean absolute pressure which may where such means are be either above or below that of the atmoshere.

What I claim and desire to secure'by Letters Patent of the United States is 1. In-the operation of a boiler and economizer the process which consists in maintaining a corrosion-preventing water in the boiler, withdrawing a portion of such water from the boiler, admixing feed water therewith, maintaining a body of such mingled waters and permitting the air and gases to escape therefrom, and feeding said mingled waters through an economizer and thence .into the boiler.

2. The method of feeding a plurality of boilers consisting in maintainin a corrosion-preventing water in the boi ers, with; drawing a portionof such water from the boilers, admixing the feed water therewith, maintaining a body of such mingled waters, and distributing said 'water to economizers and thence to said boilers.

3. The herein described method consisting in mingling the main supply of water with water from a plurality of boilers, and then distributing the mingled volume to a series of economizers and regulating the amount of water taken from each boiler in proportion to the amount of feed water delivered tothe boiler for the purpose described.

4. The method of feeding a plurality of boilers consisting in maintaining a corrosion-preventing water in the boilers, withdrawing a portion of such water from the boilers, admixing feed water therewith, maintaining a body of such mingled waters and permittin the air and gases to escape therefrom, an then distributing said mingled waters to economizers for each boiler and thence into the boilers.

5. In combination a plurality of steam boilers each having an economizer arranged to be heated by the waste gases, a common mixing tank havin connections for feeding water from the boilers thereto, a feed water connection leading into the mixing tank, said tank being arranged to permit air or gases to escape from the water therein, and connections from said tank arranged to distribute the water from the mixing tank to the economizers and thence to the boilers.

6. In combination a plurality of steam boilers each having an economizer arranged to be heated by the waste gases, a common mixing tank havin connections for feeding water from the boi ers thereto, a feed water connection leading into the mixing tank,

said tank being arranged to permit air or gases to escape from the water therein, connections from said tank arranged to distribute the water from the mixing tank to the economizers and thence to the boilers, and indicators to show the proportion of boiler water drawn from the different boilers for mixing with the feed water.

7. In the operation of a boiler and economizer the process which consists in maintaining a corrosion-preventing water in the boiler, withdrawing a portion of such water. from the boiler, admixing feed water therewith, maintaining a body of such mingled waters under reduced pressure to aid in removing the air and gases therefrom, and feeding the mingled waters through an economizer and thence into the boiler.

In testimony whereof I have hereunto signed my name in the presence of two subscribing witnesses.

DAVID S. JACOBUS.

Witnesses:

M. E. MCNINGH, CHARLES S. JONES.

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