US1255170A - Steam-boiler economizer and method of operating the same. - Google Patents

Description

STEAM BOILER ECONOMIZ APPLICATION FILED DEC. 8.19M.

D. S. JAC'OBUS.

ER AND METHOD OF OPERATING THE SAME.

Patented Tlieb. 5, 191&

3 SHEETSSHEET I.

' ATTORNEY D. s. JACOBUS.

STEAM BOILER ECONOMIZER AND METHOD OF OPERATING THE SAME.

APPLICATION FILED DEC. 8. 1914.

3 SHEETS-SHEET 2- INVENTOI? BY A 9/ M ATTORNEY/ 0. s. mcosus. STEAM B'OILER ECONOMIZER AND METHOD OF OPERATING THE SAME.

APPLIQATION FILED DEC.8, I914;

Patented Feb '3 SHEETSSHEET a 'IIVI/EIVTOR 19M 11). BY I I T BAA/Y1) WATTORA/EVM WITNESSES.- Q I p 1 DAVID S. JACOBUS, OE JERSEY CITY, NEW JERSEY, ASSIGI NOEI T0 THE EABCOCK & WIJLCOX COMPANY, OF JBAYONN E, NEW JERSEY, A CORRORATION OF NEW JERSEY.

STEAM-BOILER ECONOMIZER AND METHOD OF OPERATING THE SAME.

To all whom it may concern:

Be it known that I, DAVID S. JACOBUS, 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 afiect the iron. Ihis is often prevented or minimized by the addition to the water of a neutralizing reagent,

such as carbonate of soda or lime, the re-- agent being added until it accumulates in the boiler t a point where the amount per gallon of water in the boiler, or the degree of concentration, is such as to efiect 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 point; 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 Specification of Letters Patent.

,and carbo ic acid gas in the feed water add to, or in some cases may he the sole cause of, corrosion.

Patented F sh. 5, I911, Application filed December 8, 1914. Serial No. 876,013.

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 difliculties. 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 in crease the amount from the hot well, the latter being distilled water coming from thecondensers in the plant. But water of p 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 toaid in preventing internal and external corrosion of a two-stage economizer which may be such as described in my Patent No. 1,219,320 granted March 13, 1917. In such two stage economizers the water passing to the high pressure stage is heated solely by the waste gases. In my present invention I use some of the boiler water to aid in heating the water passing into the high pressure stage, and also introduce elements which aid in preventing corrosion of the tubes of the high pressure stage.

My invention will be understood by ref erence to the accompanying drawings in which Figure 1 is a somewhat diagrammatic side elevation, partly in section, of a plant comprising a two-stage economizer; Fig. 2 a diagrammatic plan to illustrate the use of my invention in connection with a plurality of boilers; and Fig. 3 a diagrammatic plan View of two boiler units, each having its individual mingling tank. Similar reference numerals indicate similar parts in the several views.

In Fig. 1 I have shown a boiler-of standard design in which the numeral .1 designnates a bank of inclined generating tubes expanded into front and rear headers. The boiler may be fired by any well-known or usual means, a chain grate stoker 2 being indicated. The-gases from the furnace flow through the boiler, as indicated by the arrows, to a flue 3 leading to the uptake 4. Located inthe flue and, as shown, above the boiler, is an economizer comprising a low pressure stage 5 and a high pressure stage 6. These stages consist of tubes fitted into upper and lower boxes, the high pressure stage, composed of wrought iron or wrought steel tubes and headers and subjected to the action of the. hottest gases, and the low pressure stage composed of cast iron tubes and headers and subjected to the action of the coldest gases. [7 indicates the source of the main supply, such as the hot well, to which the condensed steam from the plant is run, this being distilled water and practically free of chemical reagents. The main supply of water is pumped by a pump 8 through pipe 9 to the low pressure stage 5. The water flows through the tubes of the low pressure stage and leaves said stage through pipe 10, and is delivered into a tank 11 near the upper part thereof. .A valved pipe 12 leads from the boiler, from the steam and water drum 13, through the connection 13, or from the mud drum 13 through the connection 13 through which pipe 12 boiler water is forced into tank 11 where it is caused to'mingle with the main supply by flowing over a' series of perforated shelves 14f A relief valve 15 is placed above the tank 11, and the air and gases permitted to escape through said valve, or are withdrawn through a separate connection 16 to which an 61601301 or air pump may be connected to maintain the pressure below that of the atmosphere, if desired. The tankll is provided with a blow-off connection 11 for removing any mud or sediment that may be deposited.

The tank 11 serves the purpose of mingling the water from the low pressure stage of the economizer with a certain amount of water from the boiler and of permitting air and gases to escape from the water after it has been heated, corrosion of the high pressure stage by air or gases being thereby prevented or minimized by the'removal of the air or gases, and through the introduction of certain elements in the boiler water. The

- water from tank 11 flows downward through pipe 17 to pump 18, and is forced by the latter through pipe 19, against the boiler pressure, to the inlet end of the high pressuredensity of the water.

'11 can be made to contain a sufficient amount of the reagent to prevent interior corrosion of the tubes of the high pressure stage without raising the temperature of the water in the tank above a point which will interfere with the economy of the plant. The amount of the chemical reagent in solution in the boiler may be graduatedby adding more or less of such reagent, either intermittently or continuously, to the tank 11 or by introducing it into the hot well. The degree of concentration of the Water in the boiler may be determined by the standard method of chemical titration, v or by measuring the The make-up Water may be introduced into the hot well 7 or the tank 11, and if a chemical treatment is necessary the reagent may be introduced along with the make-up water. i

The water from the hot well 7, which enters the low pressure stage of the economizer through pipe 9, may be at the temperature of approximately F., and this water is heated when it passes through the low pressure economizer stage. When mingled with the boiler water the temperature of the water in tank 11 is above a temperature which will prevent sweating on the outside of the wrought iron or steel tubes of the high pressure stage 6, say 120 F., and this prevents corrosion on the exterior of said tubes. As

the pressure in stage 5 of the economizer isv From the foregoing description it will be seen that I prevent or minimize corrosion of the high pressure stage of the economizer, by eliminating the air and gases from the water, and by adding a certain amount of water from the boiler containing elements which resist corrosion.

The description and drawings give what I consider the preferable way of applying the invention to a two stage economizer, namely, by introducing the water from the boiler into the inlet to the high pressure stage. In certain instances it may be advisable to introduce the water from the boiler to the inlet of the low pressure s age in which event the results will be in line with those secured with a single stage economizer, as far as preventing sweating and interior corrosion of the low pressure stage is concerned. Such a mode of operation is described in a companion application filed of even date herewith.

By returning the water from the boiler, in which the reagent may be allowed to concentrate to any desired amount, a suflicient 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 fromthe boilers, and for any chemical reaction which may take place within the economizers and boilers.

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 matter in the water which is drawn oii may be removed.

The invention is not, however, limited to the use of boiler water to which a chemical reagent had been added. In its broad aspect it includes the return of a certain amount of water from the boiler to the economizer. Where the water used for making up for leakage and for blowing down the boilers, or what is known as the make-up water, containsin itself the necessary elements to pre vent corrosion, no reagent need be added.'

Whether the make-up w ater'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 eco'nomizer. The following example will serve to make my meaning clear. As- .sume that there is 10 per cent. ofemake-up water containingS 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 pound ofwater containing 100 grains per gallon is withdrawn from the boiler and mingled with 5 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 the original, 0.73 grains, leading toa lesser amount of interior corrosion.

By practising the 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.

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 the diagran'mlatic plan View of Fig. 2 I have shown my invention as applicable to a plurality of boilers with a common mixing tank. In this arrangement the main sup ply of water from any source, preferably from thehot well 7, is delivered by pump 8 through a common pipe 9, having valved controlled branches 9, to the. low pressure stage 5 of each boiler of the plant. After flowing through the latter the water passes by the branch connections 1Q to a common pipe 10 which conducts it to the mixing tank 11. Leading from each boiler are valved connections 12' to a common pipe 12 by which boiler water is conducted through pipe 12 to the tank 11 to be there mingled with the main supply coming from the low presure stages of the economizers. From the tank 11 the mingled volume is led through pipe 17 to pump 18 by which pump it is delivered to a common pipe 19, and distributed therefrom, through pipes 19 to the high pressure stage 6 of each economizer of the plant. From the high pressure stage the water is conducted by a pipe 20 and valved branches 20 to the corresponding boiler. The pipes 9, 10, 12 and 19 are shown as open-ended to indicate that they may be connected to more than two boilers, and the branch connections, 9, 10, 12 and 19 have valves for regulating the flow of waterthrough said connections or simply for closing off the supply when a boiler is laid ofi.

Thermometers 22 are indicated as placed in the pipes 10 leading from the low pressure stages of the economizer to the common pipe 10. These thermometers are important in. the operation of the plant as the valves in the pipes 9 should be adjusted to give the desired outlet temperature for the low pressure stages of the economizers. If the thermometers were not used as a guide for the adjustment of these valves, the exit temperature "for one low pressure stage might be much higher than the other.

In operating two or more boilers in ac cordance with the arrangement of Fig. 2 care must be exercised to maintain the amount of concentration in the boilers at about the same point, for, should a matein the boiler from which the less amount is drawn would soon reach a higher degree of concentration than the other boilers. In the arrangement diagrammatically shown in Fig. 3the necessity of making a close adjustment of the water allowed to flow from each boiler is eliminated, as all of the water taken from the interior of a particular boiler, and mingled with the feed water, is returned to the same boiler from which it is withdrawn.

Referring to Fig. 3, the feed water from any suitable source, such as the hot well 7, is led through a pipe to a feed pump 23, and is delivered through a common pipe 24 and valved branch connections 25, to the low pressure stages 5 of the economizers. From the latter the water is conducted through valved branch connections '26 to a common pipe 27 by which it is delivered to a tank 11. From said tank the water is conducted by a pipe 28 to a feed pump 29, and is forced by the latter through a common pipe 30, having valved branch connections 31, into mingling tanks 32, one such tankbeing provided for each boiler. The tanks 82 are preferably so arranged that any mud or sediment in the.

water will'settle to the bottom from whence it can be blown off through the valved connections 32'. Water from the boilers is led through pipes 33 having valved branch connections 34 with the boilers, to pumps 35 and by the latter delivered through pipes 36 to the corresponding tanks 32. In the ordi nary operation of the plant the valves in branches 34 are left wide open and regulating valves 37 are placed in the pipes 36 between the pumps 35 and the mingling tanks 32. The water leaving the tanks 32 passes through pipes 38 into the high pressure stage 6 of the corresponding economizer, and from the latter through pipes 39 and branches having feed valves 40 and ordinary check valves 41, into the boilers. Thermometers 31, 42 and 43 are placed in the valved connections 31 and in the pipes 36 and 38 for indicating, respectively, the temperature oi. the feed water entering the tanks 32 the boiler water entering the tanks 32 an the temperature of the mingled water leaving said tanks. By noting the difference in temperature between incoming and outgoing water, the amount returned from the boiler to the feed water may be determined. The pumps 35 require a comparatively small amount of power as they overcome only the lllfl'erence in pressure between the boiler and the feed water entering through pipe 30.

The pipes 24,, 27 and 30 are shown as open-ended to indicate that they may-heused for more than the two boilers shown.

The mixing tank 11 is also provided with blow-off connections 11 for removing any mud or sediment that may collect from the feed water after it passes through the low pressure economizer stages. Where a chemical reagent is necessary 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 ofi' 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 to be too low, a certain amount of a reagent in solution may be pumped directly into the boiler by hand or by other means.

Thermometers 22 are indicated as placed in the pipes 26 leading from the low pressure stages of the economizer t0 the common pipe 27. These thermometers are important in the operation of the plant as the valves 26 in the pipes 26 should ordinarily be adjusted to give the desired outlet temperatures for the low pressure stages of the economizer.

As has been stated, the drawings are diagrammatic. Certain common and well known features such as safety valves for the economizers have not been shown in order to emphasize the features which apply more particularly to the invention. the supply of make-up water and of maintaining the proper levels of water in the hot wells as well as regulating the water levels in the mixing tanks or heaters may be carried out in many well known ways. These are operating features aside from the principles of my invention which I have described.

By the word pressure in the claims, as applied to the mingled water in the tank 11, I mean absolute pressure which may be either above or below that of the atmosphere.

What I claim and desire to secure by Letters Patent of the United States is 1. In the operation of boilers with artificially softened or naturally soft water, the process which consists in passing the main supply of water throu h a section of an economizer, then admixlng such water with hot concentrated liquid from the boiler, and then forcing the mingled volume to another section of the economizer at a higher pressure than the first section of the economizer, and thence into a boiler.

2. In the operation of boilers with artificially, softened or naturally soft water, the process which consists in passing the main supply of water through a section of an economizer, delivering the heated water to a tank, admixing such heated water with hot concentrated liquid from the boiler and permitting the air and gases to escape therefrom, and then forcing the mingled volume Regulating to another section of the economizer at a higher pressure than the first section ofthe economizer, and thence into a boiler.

3. The herein-described method consisting in heatin the main supply of water in a section of an economizer, then mingling it with boiler water containing a chemical reagent, and then forcing the mingled volume through a section of the economizer subjected to the hottest gases and thence into a boiler.

4. In the operation of boilers with artificially softened or naturally soft water, the process which consists in passing the main supply of water for a plurality of boilers through corresponding economizer sections,

admixing the heated water from a plurality of said sections with hot concentrated liquid from the boilers, then distributing the mingled volume to another section of the economizers at a higher pressure than the first sections, and thence into the boilers.

5. In the operation of boilers with artificially softened or naturally soft water, the process which consists in passing the main supply of water for a plurality of boilers through corresponding economizer sections, admixing the heated water from a plurality of said sections with hot concentrated liquid from the boilers, then distributing the mingled volume to another section of the economizers at a higher pressure than the first sections, thence into the boilers, and maintaining a concentration of the ,Water within desired limits in the different boilers.

6. In the operation of boilers with artificially softened or naturally soft water, the process which consists in passing the main supply of water for a plurality of boilers through corresponding economizer sections, delivering the heated water from a plurality of boilers to a common mingling tank, ad-

mixing such heated water with hot concen-.

trated liquid from the boilers and permitting the air and ases to escape "therefrom, and then distributing the mingled volume to another section of the economizers at a higher pressure than the first sections, and thence into the boilers.

7. In combination, a steam boiler, a sectional economizer located in a passage for the products of combustion, connections for conducting the feed water through said economizer, and means intermediate successive sections of said economizer permitting the escape of air from the water and for mingling the water with a portion of the boiler water containing a chemical reagent.

8. In combination, a steam boiler, a sectional economizer located in a passage for the products of combustion, connections for conducting the feed water at a low pressure through one section of the economizer, means intermediate successive sections for mingling the water with a chemical reagent, and means for forcing the treated water under higher pressure through another section of the economizer.

9. In combination, a steam boiler, a sectional economizer located in the passage for the products of combustion, connections for conducting'the feed water at a low pressure through a section of the economizer subjected to the coldest gases, means intermediate si'iccessive sections for mingling the feed water with a portion of the boiler water containing a chemical reagent, and means for forcing the water under higher pressure through the section of the economizer subjected to the hottest gases.

10. In the operation of a boiler and economizer, the process which comprises establishing a relatively high concentration of corrosion-preventing salt in the Water in such boiler, passing the main supply of water through a section of an economizer, returning a portion of the liquid from the boiler and admixing the heated feedwater therewith, and then forcing the mingled volume to another section of the economizer at a higher pressure than the first section of the economizer, and thence into a boiler.

11. In combination, a steam boiler, an economizer having low pressure and high pressure stages, a tank intermediate said stages into which the water from the low pressure stage is passed, means for 1ntroducing boiler Water into said tank, and means for maintaining a pressure in said tank adapted to aid in the removal of the air and gases from the mingled water.

12. In combination, a steam boiler, an economizer having low pressure and high pressure stages, a tank intermediate said stages into which the water from the low pressure stage is passed, means for introducing boiler water into said tank, and means for maintaining a pressure above that of the atmosphere in said tank and adapted to aid in the removal of the air and gases from the mingled water.

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

]DAVID S. JACOlB US. Witnesses M. E. MoNINoH, Creams Jones.

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