US1442274A

US1442274A - Steam-boiler economizer and method of operating the same

Info

Publication number: US1442274A
Application number: US210212A
Authority: US
Inventors: David S Jacobus
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1914-12-08
Filing date: 1918-01-03
Publication date: 1923-01-16
Anticipated expiration: 1940-01-16

Description

Jan. 16, 1923.

D.S.1ACOBUS. STEAM BOLER ECONOMZER AND METHOD 0F OPERATING THE SAME. ORIGINAL ILED 550,8. 191'4.

M Tfr /H' A TTORNEYS.

Patented Jan. 16, 1923.

UNITED STATES PATENT oFFicE.

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

STEAM-BOILER ECONOMIZER AND METHOD OF OPERATING THE SAME.

Original application iiled December 8, 1914, Serial No. 876,010. Patent No. 1,314,140, dated August 26,

1919. Divided and this application led January 3, 1918.

To @ZL 'whom it may' concern.'

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

The present application is a division of my Patent No. 1,3l4,140,-granted August 26, 1919. As stated in that application, corrosion or pitting in the interior of a boiler is due to elements in the water that oxidize or otherwise affect 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 the matter in solution in the water contained in the boiler accumulates 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 periday. 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. or tombe more exact, the resulting compound 'formed through the reagent acting on any impurities in the feed water and through the presence of an excess of the reagent over that required to act on the impurities. may be allowed to concentrate in the boiler to the pounds might give good results where the two grains per. gallon would not.

An economizer cannot beprotected from serial No. 210,212.

interior corrosion by the addition of a reagent from time to time as in a boiler, as the reagent would pass directly through the econmizer with the water; again, should the reagent be added continuously to the feed water the elements 'in'the'feed water cannot be made to concentrate in the economizer in the way that they do in a boiler; In the numerical example just given, ifv twenty grains were needed to prevent corrosion it would be necessary to treat the feed water with twenty grains per gallon to properly protect the economizer. which would make the treatment more costly than for a boiler and require the boiler to 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 carbonio 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 towards 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 diiliculties, 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 feed water of the desired purity for the boiler may cause trouble through corrosion of the economizer. particularly if it is one of wrought iron or wrought steel.

The purpose of the present invention. as well as that of my prior application. 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 ofwater from the boiler 'to the inlet of the economizer. B y returning the water from the boiler in which the reagent or the resulting compounds may be allowed to concentrate to any desired amount, a sufficient quantity of the reagent or its compound 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 economizer, 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 waterbecause of the condensation of `moisture contained in the fine gases. l

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 settling chambers the mud or other suspended mattei' in the water which is drawn off may be removed.

The invention is not, however, limited to the use of boiler water to which a. chemical reagent has been added. In its broad aspect it includes the return of a certain amount of water from the boiler to the inlet of the economizer. Vhere the water used for making up for leakage and for blowing down the 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. The following example will serve to make my meaning clear. Assume that there is 10% of make-up water containing eight grains of material per gallon of al 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 pei` 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 andeconomizer are operated in accordance with the present invention, and one pound of water containing 100 grains per gallon is withdrawn from the boiler and mingled with live pounds of the water containing 0.73 grains per gal- Again assume that the one pound of water withdrawn from the boiler is at a temperature of 390o F. and is mingled with five pounds of water at 80o F. The final temperatureof the mixture would be about 130o F., which would be above that at which sweating would occur on the exterior surface of the economizer, and heating the water in the way described would obviate the exterior corrosion which occurs in economizers through such sweating. By practicing the vpresent 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 to about 1309 F., 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.

In my prior Patent No. 1,314,140 I have described a system by which the method may be carried out with a single boiler and its economizer, and one in which two or more boilers and economizers are used in co-nnection with a single or common mixing tank. In operating according to the latter system care must be exercised to maintain the amount of concentration in the boilers at about the same point. Should a materially less 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 less amount of water is drawn, would soon reach 'a higher degree of concentration than in the other boilers.

One of the objects of the present linvention is to obviate the necessity of an adjustment of the amount -of water drawn from the boiler for mingling with the feed water in order to maintain a given amount of concentration in the boiler, and will be understood from the following description, taken in connection with the accompanymg drawings in which Fig. 1 is a diagrammatic plan view of two boilers, each boiler having its individual mingling tank; and Fig. 2 a side View of one of the mingling tanks with its connections.

Referring to the drawings, the two boilers are indicated by the numerals 1 and 2, and

the economizers by the

numerals

3 and 4. The feed water from any source, such as the hot well 5, is drawn through pipe 6 by a pump 7 and delivered through a pipe 8, common to all the boilers, to the valved branch connections 9 leading to mixing' tanks 10, which tanks are under the pressure of the corresponding boiler. The pipe 8 is shown as open-ended to indicate that it may be used for more than the two boilers illustrated. Water from the boilers is conducted through pipes 11, having valved connections 12, to pumps 13, and thence throughy i pipes 14 to their respective mixing tanks 10.

In the ordinary operation of the plant the valves in branches 12 are left wide open, and the amount of water from the boiler is regulated by adjusting the speed of the pumps 13, and by the regulating valves 14 which are placed in the connections between the pumps and the mixing tanks. From the mixing tanks the mingled feed water and boiler water passes through pipes 15 into the corresponding economizer, and

from the latter through pipes 16, having feed valves 17 and ordinary check valves 18, into the boilers. Thermometers 19 and 20 are placed in the pipes 9 and 15 for indicating, respectively, the temperature' of the quire a comparatively small amount of.

power as they overcome only the difference in pressure between the-boiler and the feed water enteringthe economizer through ipes 15, this difference in pressure being ma e up by the frictional resistance of the water through the economizers and pipes and through any throttling action at the regulating valves 14. Fans 21 may be used for drawing the gases away from the economizers and boilers and discharging them into the uptakes 22.

The make-up water may be added either at the hot well or in the mixing tanks 10. If a chemical reagent is required it may be introduced along with the makeup water, or it may be introduced into the boiler in any other way. I prefer, however, to introduce such reagent along with the make-up water, as by so doing the amount of concentration in each of the boilers may be regulated solely by blowing olf more or less water from the boiler. Should a boiler be accidentally blown down to an extent that causes the concentration of the contained water in that boiler to be too low, a given amount of .the reagent, in solution, may be pumped directly into the boiler by hand or by other means.

The mixing tanks 10 may be provided with blow-off connections 23 for removing any mud or sediment which lmay collect in the tanks.

There are advantages in the system herein described over one employing a common mingling tank, as it is easier to maintain a given amount of concentration in each one of the boilers. Furthermore, no adjustment of the amount of water drawn from a boiler for mingling with the feed water need be made in order to maintain a given amount of concentration in the boiler, as all of the water from a given boiler, for mingling with the feed water, is returned to the same boiler.

What I claim and desire to secure by Letters Patent of the United States is 1. The method of operating a boiler and an economizer, whereby the water in the boiler may, by the presence of a water treatment chemicalA in the feed water, be maintained charged with a desired quantity` of such chemical in excess of the amount re- 'quired for the chemical action in the. boiler,

and the water passing through the economizer may be charged with a percentage of the chemical greatly in excess of the percentage in the feed water, which consists in providing a feed water charged with a quantity of the chemical suiiicient to give the desired percentage in the boiler, drawing water from the boiler and mingling it at boiler pressure with the feed water in an amount sufficient to give the mingled water a percentage of the chemical greatly in `excess of the percentage in the feed water. alone, feeding the lmingled water to the economizer and delivering the water from the economizer to the boiler.

2. The method of operating a boiler and an economizer, whereby thewater in the boiler may, by the presence of a water treatment chemical in the feed water, be maintained charged with a desired quantityl of such chemical in excess of the amount required for theJ chemical action in the boiler, and the water passing through the economizer may be charged with a percentage of the chemical greatly in excess of the percentage in the feed water, which consists in providing a feed Water charged with a quanl tity of the chemical suiiicient to give the desired percentage in the boiler, drawing water from the boiler and mingling it at boiler pressure with the feed water in an amount sufficient to give the mingled water a percentage of the chemical greatly in excess of the percentage in the feed water alone, and

a temperature high enough to prevent ex-AY ternal sweating in the economizer, feeding the mingled water to the economizer and delivering the water from the economizer to the boiler.

3. The method of operating a boiler, consisting of withdrawing water containing corrosion-preventing elements from the boiler,

mingling it with the feed water for the boiler, feeding the mingled volume to an economizer, delivering' the water from the economizer to the boiler, Amaintaining the water drawn from the boiler under boiler pressure from the time it is withdrawn until it is fed to the economizer, and regulating the amount of water taken from the boiler in accordance with the feed entering the same.

4. The method of operating a plurality of boilers, each connected to a separate economizer, whereby the water in each boiler may, by the presence of a water treatment chemical in the common'feed water supply for all the boilers, be maintained charged with a desired quantity of such chemical in excess of the amount required for the chem ical action in the boiler, and the water passing through each economizer may be charged with a percentage of the chemical greatly in excess of the percentage in the feed water, which consists in providing a common source of supply of feed water at boiler pressure, drawing water from each boiler and mingling it at boiler pressure with the feed water for that boiler in an amount suicient to give the mingled water a percentage of the chemical contained in the boiler Water greatly in excess of the percentage `in the feed water alone, feeding the mingled water for each boiler to a corresponding economizer, and delivering the water from each economizer to its boiler, whereby the water drawn from a given boiler is returned to that boiler.

5. The method of operating a plurality of boilers, each connected to a separate economizer, consisting of withdrawing water containing'l corrosion-preventing elements from each boiler, mingling it with feed Water from a source common to all the boilers, feeding the mingled volume for each boiler to a corresponding economizer, delivering the water drawn fromthe economizer to its boiler, maintaining the water drawn from each boiler under boiler pressure from the time it is withdrawn until it is fed to the economizer, and regulating the amount of water taken from each boiler in accordance with the water fed to that boiler.

6. .In-combination, a plurality of steam boilers each having an economizer arranged to be heated` by the waste gases, a mingling tankfor e-ach boiler adapted to maintain the boiler pressure therein, means for maintaining, at boiler pressure, a common feed Water supply for all of the boilers, means for delivering the main supply of water and also water from each boiler under boiler pressure to the corresponding tank, a connection from each tank to the corresponding economizer and a connection from the latter to its boiler, and means whereby the amount of water taken from each boiler may be regulated in accordance with the water fed to that boiler.

7 In combination, a steam boiler having an economizer arranged to be heated by the waste gases, a mingling tank for the boiler adapted to maintain boiler pressure therein, means for delivering the main supply of water and also water from the boiler under boiler pressure to the tank. a connection from the tank to the economizer and a connection from the latter to the boiler, and means whereby the amount of water taken from the boiler may be regulated in accordance with y DAVID s. lJAcoBUs.

Witnesses:

HERMAN FISCHER, HERMAN B. SMITH.