US2726645A

US2726645A - Preparing chemical solutions for conditioning boiler water

Info

Publication number: US2726645A
Application number: US249091A
Authority: US
Inventors: Bertram J Cross
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1951-10-01
Filing date: 1951-10-01
Publication date: 1955-12-13
Anticipated expiration: 1972-12-13

Description

Dec. 13, 1955 B. .1. CROSS PREPARING CHEMICAL. SOLUTIONS FOR CONDITIONING BOILER WATER Filed Oct. 1, 1951 cHEMmAL lNJECTlON TANK Pump

CHE ucAL souu-nou Fig. I.

INJECTION INVENTOR Bertram J. Cross BY lailgfi United States Patent PREPARING CHEMICAL SOLUTIONS FOR CONDITIONING BOILER WATER Bertram J. Cross, Nyack, N. Y., assignor to Combustion Engineering, Inc., New York, N. Y., a corporation of Delaware Application October 1, 1951, Serial No. 249,091

4 Claims. ((21. 122 s79 This invention relates to preparing chemical solutions for conditioning the water utilized in steam generating boilers, and it has special reference to a novel method and improved means for accomplishing such preparation.

When chemicals used for conditioning boiler water are introduced into a boiler, they are usually admixed with or dissolved in water, and the resulting solution is forced into the boiler by means of a pump specially designed for delivery in accurate quantities against the boiler pressure. The pump discharges the solution through a relatively small pipe into the steam generating boiler, as at the drum thereof.

In many industrial power plants where condensate is not available for admixture with or for dissolving the chemicals prior to their delivery into the boiler, it is usual to use either local tap water or boiler feed water to make up the solution. Such waters usually contain calcium, magnesium and other salts which react with the chemicals to form unsoluble products. These products collect within and foul the chemical feed pump and depositin the chemical feed lines to clog them. Even when condensate has been used for admixture with the chemicals, similar clogging has occured because of the contaminating salts from condenser leakage that frequently are present in the condensate.

According to the invention I overcome the above mentioned objections of fouling the chemical feed pumps and of clogging the feed pipes by using water from the boiler itself for making up solutions of the chemicals. Such boiler water, even if it contains a high concentration of dissolved solids, does not contain unreacted hardness, or is substantially free from ingredients forming precipitates when reacting with the chemicals.

Other objects and advantages of my invention will become apparent from the following description of an illustrative embodiment thereof when taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic view showing a steam generating boiler having associated chemical feed apparatus arranged in accordance with the invention to draw water from the boiler for admixture with the water conditioning chemicals.

In the drawing like numbers refer to like parts, and reference character 1 designates a steam generator having an upper steam drum 2 and a lower water drum 3 interconnected by a bank of steam generating tubesv 4. Hot gases from a furnace or from a process (not shown) may flow across the bank of tubes in the direction shown by the arrow 5 giving up heat to the tubes and the boiler water therein to generate steam.

In the steam generator feed water is supplied to the boiler drum 2 through pipe 6 by a pump (not shown), and the generated steam collected in drum 2 leaves the boiler via offtake pipe 7. Moreover, water is bled from the generator through a pipe 8 in controlled amounts by means of blow off valve 9, thereby maintaining a desired concentration of dissolved solids in the water within the generator.

Patented Dec. 13, 1955 Chemicals for conditioning the boiler water in each generator 1 are first introduced into a solution tank 10 from a chemical supply tank 11. These chemicals may be of the conventional variety customarily used to precipitate the scale-forming salts in the raw water fed into the boiler at 6 so that those salts form a dispersed sludge which can be removed with the boiler blow down through valve 9. Such chemicals may be delivered into solution tank 10 at a properly controlled rate in any suitable manner as by the aid of a device 12 that feeds into pipe 13; the feeder here illustrated at 12 being driven by a motor through reduction gearing 14.

Water for admixing or for dissolving the chemicals in the solution tank 10 is delivered thereinto via pipe 15.

In the preferred arrangement disclosed, the aforementioned pipe 15 receives boiler water from a pipe 17 which is connected to the outlet port 18 of a hydraulic motor 19. Said hydraulic motor 19 has its inlet port 20 connected to pipe 21 which conveys boiler water from the blow off line 8 into which it is connected at point 21'. A cooler 16 is serially connected into line 21 and cools the withdrawn boiler water prior to its entry into the hydraulic motor 19.

The pump 22 removes the chemical solution from solution tank 10 via pipe 23 and delivers it via pipe 24 into the steam generator 1.

The hydraulic motor 19 is directly connected through shaft 30 to the centrifugal pump 22. This motor 19 is driven by boiler water under pressure supplied through pipe 21 from blow oh line 8. The boiler water which is exhausted from the motor 19 at outlet 18 flows at a reduced pressure through

pipes

17 and 15 to the solution tank 10. A control, such as a float control valve 31, may be connected in line 15 to regulate the flow of water into the solution tank 10. Since the hydraulic motor 19 must use more water than is needed by the solution tank 10 in order to pump the water leaving tank 16 back into the boiler and overcome the power loss inherent in the pumping system, the excess water is carried ofl through pipe 32 into the blow off line 8 beyond the blow off valve 9 and into the flash tank 33 and thence to waste; a check valve 34 being shown in pipe 32. In order to provide a reasonable operating head for forcing water through line 15 and valve 31 into tank 10 the pipe 32 is extended a distance above the tank and then extended downward to checkvalve 34.

Should it be desired to reduce the pressure of the water supply to pump 19 an adjustable pressure reducing valve 38 may be provided in the line leading to this pump.

As mentioned above, the boiler water withdrawn from blow-off line 8 in the manner here taught does not contain unreacted hardness, or is substantially free from ingredients forming precipitates when reacting with the chemicals. Therefore when such boiler water is employed as the solvent in chemical solution tank 10 there is no fouling of the chemical feed pump 22' or clogging of the chemical feed pipes 2324 by the make up solution as it flows therethrough into the steam generating boiler.-

There isanother advantage accruing from the use of boiler water in thechemical solution when acid salts such as monosodium phosphate are employed as the chemical. This salt is highly corrosive and will attack the material of the pumps 22--22', the hydraulic motor 19, and the pipe lines 23-24. My herein-disclosed use of the alkaline boiler water as a solvent will lower if not completely neutralize the acidity of this and similar salts.

While I have here shown and described illustrative apparatus for practicing my invention, it will be understood that changes in construction, combination, and arrangement of parts maybe made Without departing from the spirit and scope of the invention as claimed.

What I claim is:

1. In a steam generating boiler, the combination of a chemical feed pipe connected to said boiler; a vpump connected at its discharge end to said feed ,pipe for delivery of chemical into said boiler; a hydraulic :motor coupled with said pump to drive it; a first ,pipc leading from said boiler to the inlet of said motor for the delivery of boiler water under pressure into the motor; .a solution tank for admixture ofchemical and water; a'second pipe leading from the outlet of said motor into said solution tank, whereby water from the boiler carried to the motor by said first pipe serves to drive said motor and thereby said pump and whereby said motorin thus beingdriven serves to reduce the pressure of said boiler water flowing therefrom via said second pipe into said tank; conduit means connecting said solution tank to the inlet of said pump; and means to supply chemical to said solution tank for admixture therein with the'aforesaid boiler water reaching the tank via said second pipe, said chemicals being eifective to condition the boiler water by precipitating the scale forming salts in the raw water fed to the boiler but being non-reactive with previously conditioned boiler water.

2. In a steam generating boiler, the combination of a chemical feed pipe connected to said boiler; a pump connected at its discharge end to said feed pipe for delivery of chemical into said boiler; a hydraulic motor coupled with said pump to drive it; a first pipe leading from said boiled to the inlet of said motor for delivery of boiler water under pressure into the motor; a solution tank for admixture of chemical and water, said tank communicating with the inlet of said pump; a second pipe leading from the outlet of said motor into said solution tank, whereby water from the boiler carried to the motor by said first pipe serves to drive said motor and thereby said pump and whereby said motor in thus being driven serves to reduce the pressure of said boiler water flowing therefrom via said secondpipe into said tank; means to supply chemical to said solution tank for admixture therein with the aforesaid boiler water reaching the tank via said second pipe, said chemicals being effective to condition the boiler water by precipitating the scale forming salts in the raw water fed to the boiler but being non-reactive with previously conditioned boiler water; valve means in said second pipe responsive to the amount of solution in said tank for controlling the aforesaid flow of boiler water into the tank; and means also communicating with said second pipe for carrying away from said hydraulic motor allboiler water discharged therefrom that is prevented by said valve means from entering said solution tank.

3. In a steam generating boiler, the combination of a chemical feed pipe connected to said boiler; a pump connected at its discharge end 'tosaid feed pipe for'delivery of chemical into said boilerya hydraulic motor coupled with said pump to drive it; a first pipe leading from said boiler to the inlet of said motor fordelivery of boiler water under pressure into the'motor; a'solution tank for admixture of chemical'and-water, said tank communicating with the inlet of said pump; a secondpipe leading .from the outlet of said 'motorinto'said solution tank, whereby water from the "boiler carried to the motor by said first pipe serves to drive said motor and thereby said pump and whereby said motor in thus being driven serves to reduce the pressure of said boiler water flowing therefrom via said second pipe into said tank; means to supply chemical to said solution tank for admixture therein with the aforesaid boiler water reaching the tank via saidsecond pipe, said chemicals being efiective to condition the boiler water by precipitating the scale forming salts in the raw water fed to the boiler but .being non-reactive with previously conditioned boiler water; a blow down line connected to said boiler; a blow oif valve in said blow down line; a third pipe disposed to carry boiler water leaving said motor and not receivable by said tank from said second pipe into said blow down line beyond said blow off valve with respect to water fiow there through; and a check valve disposed in said third pipe to permit water flow therethrough only in the direction of towards said blow down line.

4. In a steam generating boiler, the combination of .a chemical feed pipe connected to said boiler; a pump connected at its discharge end to said feed pipe for delivery of chemical into said boiler; a hydraulic motor coupled with said pump to drive it; a first pipe leading from said boiler to the inlet of said motor for delivery of boiler water underpressure into the motorya solution tank for admixture of chemical and water, said tank communicating with the inlet of said pump; a second pipe leading from the outlet of said motor into said solution tank, whereby water from the boiler carried to the motor by said first pipe serves to drive said motor and thereby said pump and whereby said motor in thus being driven serves to reduce the pressure of said boiler water flowing therefrom viavsaid second pipe into said tank; means to supply chemical to said solution tank for admixture therein with the aforesaid boiler water reaching the tank via said second ;pipe, said chemicals being efiective to conditionthe'boiler water by precipitating the scale forming salts vin the raw water fed to the boiler but beingtnon-reactive with previously conditioned boiler water; a third pipe communicating with said second pipe and extending upwardly therefrom to atlevel above said tank before leading to apoint of discharge; and valve means intermediate said second vpipe and tank responsive to the amount of solution'in said tank for controlling the aforesaid flow of boiler water into the tank whereby boiler water discharging from said hydraulic motortfiows into said tank as longas said valve means permit and when rejected by the tank passes upwardly into'and through said thirdpipe.

References Cited in the file of this patent UNITED STATES PATENTS 825,971 Hutchison July 17, 1906 1,255,170 'Jacobus -Feb. 5, 1918 1,314,140 "Iacobus Aug. "26, 1919 1,341,213 'Jacobus May 25, 1920 1,442,274 Jacobus Jan. 16, 1923 1,774,211 Piccardo Aug. 26, 1930 2,151,297 Lucke Mar. 21, 1939 2,226,592 Stern Dec. 31, 1940 2,312,570 'Meier Mar. 2, 1943