US2358380A - Production of steam - Google Patents

Description

Sept. 19, 1944. E. w. BUTZLER PRODUCTION 'oF STEAM 2 'Sheets-Sheet' l Filed March 9, 1942 Ediz/ard ik @15gg/er' Sept. 1-9, 1944 E. w. BUTZLER PRODUCTION oF STEAM Filed March 9`, 1942 'Y 2 Sheets-Sheet 2 Patented Sept. 19, 1944 UNITED STATES PATENT FFICEv f PRODUCTION oF STEAM Edward W. Butzler, Westview, Pa. Application Mareas, 194,2, serial No. 433,902

n Claims. This invention relates generally to the production of steam and more particularly to a method in which one or more high pressure boilers and one or more low pressure boilers are employed and the blowdown from the high pressure boiler is supplied tothe loW pressure boiler. 'Ihe use of the blowdown from the high pressure. boiler `in the low pressure boiler results in great savings in fuel and chemicals used in treating the Water, as will be pointed out more particularly hereinafter.

In the accompanying drawings, which illustrate a preferred embodiment of the invention, as Well Vas a conventional method,

Fig. 1 illustrates in a diagrammatic manner a preferred embodiment according to the present invention, in which the bloWdoWn `from a high pressure boiler is supplied to a low vpressure boiler; and Fig. 2 illustrates a conventional method in which tWo separate boilers are employed, onebeing a high pressure boiler and the other a low pressure boiler.

Referring more particularly to Fig. 1, which illustrates a preferred embodiment of the present invention, the arrangement is such as to produce 900,000 pounds per hour of steam at 900 pounds per square inch absolute pressure and 400,000 pounds per hour of steam at 240 pounds per square inch absolute pressure. Feed Water, in the amount of 1,000,000 pounds per hour, which has been heated to a temperature of .220 F. by any suitable type of preheater, is supplied to a high pressure boiler 2. In the Water in the high pressure boiler, a P04 concentration of 60 parts per million is maintained in solution, in order to inhibit the formation of adherent scale. The methof of treating steam boiler water with phosphate in order to form the desired non-adherent sludge of calcium phosphate is more particularly described in Hall Patent 1,613,656, granted January 11, 1927, and. reference is made thereto for further details as to the proper concentration of phosphate radical in solution to prevent the calcium from being deposited as adherent scale. The boiler Water in the high pressure boiler 2 has a concentration of 2000 parts per million .oi

total solids. Y Y

The high pressure boiler 2 is blown down continuously or from time to time into the low pressure boiler, the bloWdoWn amounting to 10% ofr the Water fed to the high pressure boiler or 100,000 pounds per hour. vThis amount Vof blowdoWn maintains the concentration of total solids in the high pressure boiler at about 2000 parts per million, thereby preventing objectionable car-r c ryover of Water with the steam. The telrlperature` of the blowdown from the .high pressure boiler-is about`532 F., each pound containing 529.5 B. t. u.,

` so that the total heat in the bloWdoWn per hour is 52.9 million B. t. u. L Y

The blovvdownV from the high pressure boiler' is supplied to a loW pressure boiler `3, in which a P04 concentration of about 30 parts per million in solution and a concentration of total solids of. about 4,000 parts per millon are maintained.r

`This boiler produces 400,000 pounds per hour of low pressure steam at a pressure of 240 pounds per square inch absolute. The feed Water required in addition to the blowdoWn fromthe high pressure boiler, to produce the 400,000 pounds per hour of steam and provide adequate blowdown from the low pressure boiler amounts to 368,400 pounds per hour, which is supplied to the low pressure boiler at a temperature of 220 F. In order to produce the 400,000 pounds per hour of low pressure steam, it is necessary to supply y383.2 million B. t. u. per hour. It is to be noted particularly that the blowdown from the loW pressure boiler 3 is regulated in such manner that the Water in the, loW pressure boiler is moreconcentrated with respect to total solidsthanis the Water in the high pressure boiler 2. yInthe specic method used for illustrating the invention, the concentration of total solids in the 10W pressure boiler is 4,000 parts per million, Whereas in the high pressure boiler it is 2,000 parts per million. Furthermore, the concentration of phosphate lin, solution in the low pressure boiler is only 30 parts per million as compared with parts per million in the high pressure boiler. In order to operate at a total solids concentration in the low pressure boiler of 4,000 parts per million, the blowdown from the low pressure boiler amounts to 68,400 pounds per hour. Of this total blowdown, 18,400 pounds per hour is the regular blowdown (amounting to of the water fed to the low pressure boiler) and 50,000 pounds per hour is the amount required to take care of the solids introduced into the low pressure boiler from the blowdown from the high pressure boiler. It will be noted that the 100,000 pounds per hour of blowdown from the high pressure boiler introduces 200 pounds per hour of solids into the low pressure boiler and that the 50,000 pounds per hour of blowdown from the low pressure boiler removes 200 pounds per hour of solids. The blowdown water from the low pressure boiler 3 is at a temperature of 397 F., so that the total heat lost by blowdown is 25.4 million B. t. u. per hour.

In the preferred method according to the present invention, the total solids in the low pressure boiler 3 are maintained higher; than in the high pressure boiler 2 andthe concentration of phosphate in solution in the low pressure boiler is maintained at a lower value than the concentration of phosphate in solution `in the .highpres-Y sure boiler. This results in a double reduction in the pounds of phosphate lost in the blowdown from the low pressure boiler. Thusthe 100,000A pounds per hour of blowdown from the high pressure boiler, which has aphosphate concentration in solution of 60 parts per million, introduces 6 poundsper hourrof phosphate in solution into the low pressure b oiler. The 68,400 pounds per hour of blowdownnfrom the low pressure boiler, the water inthe low pressure boiler having a concentration in solution of partsper million, removes `2.0 pounds of phosphate insolution per hour.Y Thus 4.0 pounds per hour of phosphate in solution is `available for treating the feed water introduced into the low pressure boiler.

A partof the advantages of the present'invention can be obtained by keeping the concentra-5 ,tion of total solids in the low pressure boiler the same as in the highpressure boiler but ,maintaining a lower concentration of phosphate in solutionin the low pressure boiler than in the high pressure boiler. Thusassume that the concentration Aof total solids in both the high pressure boiler and inthe low pressure boiler is 2,000 parts per million,.that there are 60 parts per million of phosphate in solutionin the high ypressure boiler and BOparts per million'rof phosphate inY solution in the low pressure boiler. The 100,000 pounds per hour of blowdown from the high pressure boiler supplied to the low pressure boiler will introduce 6 pounds of phosphate in solution into the low pressure boiler. In order to maintain the concentration of total solids in the low pressure boiler at 2,000 parts per million, it will be necessary to blow down`100,000` pounds per hour from the low pressure boiler, in order to take care of the solids inthe blowdown from the high pressure boiler, and 44,400 pounds per hour to take care of the solids from the feed water supplied to the low-pressure boiler or a total blowdown from the low pressure boiler of 144,400 pounds per hour.- The loss in phosphate in solution is .4.3

poundsper hour, so that 1.7 pounds per'hour is available for treating the feed water introduced into Vthe low pressure boiler.

In a similar manner, apart of the advantages of the present invention may be obtained by keeping the concentration of phosphate in solution the same in the high pressure boiler and the low pressure boiler .but maintaining a higher concentration of total solids in the low pressure boiler than inthe high pressure boiler. Thus assume that the phosphate concentration in solution in each boiler is 60 parts per million, that the total solids in the high pressure boiler is 2,000 parts per million and in the low pressure boiler is 4,000 parts per million. As previously explained, the blowdown from the high pressure boiler will introduce 6 pounds of phosphate in solution per hour into the low pressure boiler. Since the concentration of total solids in the low pressure boiler is increased two-fold as compared with the concentration of total solids in the high pressure boiler, it is only necessary to blow down from the low pressure boiler 50,000 pounds per hour to take care of the solids introduced into the low pressure boiler from the blowdown from the high pressure boiler. The total blowdown from the low pressure boiler is 68,400 pounds per hour, as shown in Fig. 1. The loss of phosphate in solution is 4.1 pounds per hour, so that 1.9 pounds per hour is available for treating the feed water introduced into the low pressure boiler.

Reference is now made to Fig. 2, in which the same amount of high pressure steam and the same amount of low pressure steam as are produced in accordance with the method of Fig. 1 are produced by two separate boilers according to conventional practice.

In order to produce the 900,000 pounds per hour of high'pressure steam at 900 pounds per square inch absolute, 1,000,000 pounds of feed water at a temperature of '220 F. is introduced into the high pressure boiler 4. The blowdown from the boiler 4 is introduced into a iiash tank 5 which produces flash steam V,inthe amount of 19,000 pounds per hour at a pressure of 240 pounds per square inch absolute.

Where it is desired'to produce the same amount of high pressure steam and low pressure steam as wasproduced according to the method shown in Fig. 1, itis necessary to provide a low pressure boiler which will produce 381,000 pounds of steam per hour at 240 pounds per square inch absolute pressure. Y 'Ihis may be accomplished by the use of the separate low pressure boiler Vli shown in Fig. 2 In order to produce this amount of low pressure steam, it is necessary to feed into the boiler 6, 401,000 pounds per hour and to supply to the boiler 6, 389.2 million B. t. u. per hour. The blowdown from the boiler 6 is 5% of the feed wateror 20,000 pounds per hour. The temperature ofthe blowdown is 397 F., so that 7.4 million B. t. u.' are lost inthe blowdown perV hour.

'The method according to the present invention, as 'shown in Fig. 1, results in very material savings in fu'el, chemicals used in the treatment of the Water in the boilers, and in the preheaters and inthe amount of feed water supplied to the low pressure boiler. The saving in high level heat by the method illustrated in Fig. 1 as compared with that of Fig. 2 is shown by the following table. The computations in-this table do not include the usual heat saving brought about by passing in heat exchange relationV with feed water the unilashed blowdown water from the iiash chamber of the'high pressure boiler in the system shown in Figure 2. Y

TAaLgI posed method as compared with the method Furnace hem. shown in Fig. 2.

TABLE IV Furnace heat input L. P. boilerfFig. 2. Total'sav'mgs p97? da'l'm fuel and Chemicals Furnace heat input L. P. boiler-Fig. 1

Savings furnace heat input L. P. B ghspliate fromablowdown $i4). 3(0) Lime, soda and phosphatedue to decreased feed water require- Blowdoumheat Wants"- 306 i i l i conventional nieuwe (Fig. 2) (30,144.4) /n or $24,586.40 per year. i Proposed method (Fig. l)

For the purpose of illustrating the method, I Savings have given an example in which the high pressure Million boiler 2 operates at a pressure of 900 pounds per Furnace heatsaved 3 1'/] r 15 square inch absolute and the low pressure boiler Blowdown heat saved 12.1 3 operates at a pressure of 240 pounds per square TotalhemWL` 1&1 inch absolute. These pressures are merely il-A ot lustrative and it will be understood that other Minion pressures may be employed. Thus the terms B. n n/day. 20 high pressure boiler and low pressure boiler Tmlheat Saved 134-49 signify simply that the high pressure boiler Assuming coal oost ai bunker at sascperton, 12,5003. mammina operates at a pressure which is considerably EtirdcoasisgO'Zi eiiicieiicy, each million B. t.. u. available as higher than the pressure in the 10W pressure boiler. Y zol'-mmxsasdor $0.125 25 While I have illustrated and described a preferred embodiment of the invention, it is to be 4344X$0125=$54-3008-1Saved Per G85?- understood that the invention may be otherwise The saving in phosphate used for treating embodied or practiced within the scope of the the boiler water is illustrated by the following: following claims.Y f

TABLE II Phosphate lost by biowdo'um` using conventional ymethod (Fig. 2)

'(Blowdown from (Eq. wt, (p. p. ni. P04 in H. P. H. P. boiler #lhr.) P105) boiler water) Y 100,000 zig I H. P. boiler 1,000,000 X 3L 7 X 60 4.85 #/hr. P105 equivalent f (Eq. wt. P04) (p.p.m.ro4inL.P. ' f 2,3 7 boiler water) L. r. boiler x 3-11-7 so .45 #/hr. rio, equivalent Total.. 5.3 #/hr. P20; equivalent Phosphate lost by blowdown using proposed method (Fig. 1)

L. r. boiler x x 'i0 l 1.54 #/hr. rioiequivaienz Phosphate lost by conventional method (Fig. 2) 5.3 #/hr. P10; equivalent Phosphate lost by proposed method (Fig. l)- 1.54 #/hr. P10; equivalent Net Saving by proposed method (Fig. l). 3.76 #/lir. P40; equivalent Cost of P105, based on current market price of disodium orthophosphate anhydrous (48% P205) at 7.25/#is $0.151 per pound 24X3.76X$0.15l=$10.00 per day saving on phosphate l Thesavings in feed water is illustrated in I claim: Y f Table III, this table also showing the savings in p 1. VThe method of producing high pressure lime, soda and phosphate as P205 due to the de- 55 steam and low pressure steam, which comprises creased feed Water requirements: producing steam in a high pressure boiler from TABLE m feed water containing scale forming solids, blowing down the high pressure boiler, supplying the Feed water saved blowdown from the high pressure boiler to a low Feed water ued by)conventioiial method (Fig. 2) Pulidls/i- (m pressure boiler, and Supplying heat t0 the 10W ,000, 0i, Feed wam used by proposed method (F pressure boiler to produce low. pressure steam.

(rondom-pasaron) 1,358, 400- 2. The method of producing high pressure steam and low pressure steam which comprises F d t rsa db o osed method 32,600 f ee wa e ve ym D producing steam in a high pressure boiler from C'OSt per 'm1111011' Mund? feed water g5 feed water containing scale forming solids while Lime-soda treatmeri l 40 maintaining sufficient phosphate radical in solu- 51 tion in the boiler water to inhibit the formation $91 of adherent scale, blowing down the high pressure boiler, supplying theblowdown from the t Phosphate as (P105) l0# at l5.1/#

1,000,000 $3.91 $3.06 per day saved. 0

The total savings per day in fuel and cheniplying heat to the low pressure boiler to produce `icals is shown by Table IV. This table does not low pressure steam while maintaining suflicient Y include the cost, of the feed water itself before phosphate radical in solution in the boiler water treatment with chemicals, which, if included, to inhibit the formation of adherent scale but at would further increase the savings of the pro- 75 aphosphate concentration lower than in the high high pressure boiler to a low pressure boiler, supe the total solids in pressure boiler water, and blowing downv the low pressure boiler.

3. The method of,- producing high pressure steam and low pressure steam, which comprises producing steam in a high pressureboiler'from feed water containing scale forming solids while maintaining. suiiicient phosphate'radical in solu-V tion infY the boiler water to inhibitthe formation of adherent scale, blowing down the high pressure boiler, supplying thev blowdown 'from vthe high pressure boiler to a low pressure boiler, supplying heat to the low pressure boiler to produce low pressure steam while concentrating the total of adherent scale, blowing down the high pressure boiler, supplying the blowdown from the high pressure boiler to alow pressure boiler, supplying heat to the low pressure boiler to produce low pressure steam'whilemaintaining suicient phosphate radical in solution in the boiler water to inhibit the formation of adherent scale but at a phosphate concentration lower thanrin the" water in the high pressure boiler, concentrating boiler to a higher Value than the concentration of total solids in the water in the high pressureu boiler, and blowing down the low pressure boiler. 5. The method of producing high pressure steam and low pressure steam, which comprises producing steam in a high `pressure boiler from feed vwater containingscale forming solids whileV maintaining suicient phosphate radical in soluin the low pressure boiler the water in the low pressure tion in the boiler water to inhibit the formation ofv adherent scale, blowing down the high pressure boiler, supplying the' blowdown from the-high pressure boiler to a low pressure boiler, supplying heat to the, low pressure boiler to pressure steam while maintaining suflicient phosp hate radical insolution in the boilerwater to inhibit the formation of adherent scale but at a phosphate concentration lower than in the water in the high pressure boiler, concentrating the total solids in the water in the low pressure boiler to a higher Value than the concentration of total solids in the water in the high pressure boiler, and blowing down the low pressure boiler 1n such manner that theA blowdown from the low pressure boiler is less than the blowdown from the highpressure boiler.

6. Themethod 4of producing high pressure steam of the order offabout 900 pounds per square inch absolute -and low pressure steam of about 240 pounds per square inch absolute from ,feed water containing scale forming solids, which comprises producing steam in a high pressure boiler, while maintaining a P04 concentration in solution of about 6 0 parts per millionand a concentration of totalisolids of the order of about 2000 parts per million, blowing. down the high produce low A Y pressure boiler, supplying 'theblowdown from the high pressure -boiler to a low pressure boiler,

supplying heat to the low pressure boiler to produce low pressure steam while maintaining a P04 concentration in solution of about 30 parts per millionv and a concentration of total solids of the order of about 4000 parts per million, and blowing down the low pressureboiler.

l'7. Apparatus for producing high pressure steam and low pressure steam from feed water containing scale forming solids, which comprises a high pressure boiler, a low pressure boiler, and means connecting the high pressure and low pressure boilers for supplying blowdown from the high pressure to the low pressure boiler, and means forsupplying phosphate' radical -to the high pressure boiler.

8. The method of producing high pressure steam and low pressure steam, which comprises producing steam in a high pressure boiler from feed water containing scale forming solids while maintaining suicient phosphate radical in solution in the boiler waterto inhibit the formation of adherent scale, blowing down the high pressure boiler, supplying the `blowdown from the high pressure boiler to a low pressure boiler, supplying feed water containing scale formingsolids to the low pressureboiler, supplying heat to the lowpressure boilertoproduce low pressure steam while concentrating the total solids in the water to a higher value than the concentration of total solids in the water in .'thef-highpressure boiler, and blowing down the low pressure boiler.

9. The method of 'producing high pressure steam and low pressure steam, which comprises producing steam in a high pressure boiler from feed water containing scale forming solids while maintaining sufcient phosphate radical in solution in the boiler water to inhibit the formation of adherent scale, blowing down the high pressure boiler, supplying high pressure boiler to av low pressure boiler, supplying feed water containing scale forming solids to the low pressure boiler, supplying heat to the low pressure boiler to produce low pressure steam while maintaining sufficient phosphate radical in A solution" in the boiler water to inhibit the formation of adherent scaleV pressure boilers for supplying but at a phosphate concentration lower` than in thewater 4in the high pressure boiler, concentrating the total solids in the-water in the low pressure boiler to a higher Value than the concentrationof total solids in the water-in Vthehigh pressure boilerand blowing down the low pressure boiler.

10. Apparatus for ,producing high pressure steam and low pressure steam from feed water containing scale forming solids, which comprises a high pressure boiler, `a low pressure boiler, means connecting the high pressurev and low blowdown from the highV pressure to the low pressure boiler, means for supplying feed water containing scale'forming solids` to Vthe low pressure boiler, and means forsupplying phosphate radical to the high pressure boiler. EDWARD W. BUTZLER.

the blowdown from the`

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