US1742998A - Method and apparatus for treating liquids - Google Patents

Description

Jan. 7, 1930. J. R. M DERMET 1,742,998

METHOD AND APPARATUS FOR TREATING LIQUIDS Filed Aug. 16, 1922 Sheets-- Sheetv l v o E/ECTOI? Ly 8 CONDENSER 17 6 l/ E N T IND UCT/ON HE/l 7'51? w, l l [I )LZZZTU I I I 1 l rymmosm 7/0 11 VALVE. HE ,4 TIN 6 MED U M WATER OUTLEI M INVENTOR Jan. 7, 1930.

J. R. McDERMET 1,742,998

METHOD AND APPARATUS FOR TREATING LIQUIDS Filed Aug. 16', 1922 2 Sheets-Sheet INVENTOR JOHN R. MCDERMET, OF JEANNETTE,

Patented Jan. 7, 1930 PATENT OFFICE PENNSYLVANIA, ASSIGNOR TO ELLIOTT COX;

, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA METHOD AND APPARATUS FOR TREATING LIQUIDS Application filed August 16, 1922. Serial No. 582,151.

The present invention relates broadly to degasifying or deaerating feed water, such for example as fed to boilers, economizers and the like, and more particularly to a method and apparatus for effectively removing air and other entrained gases from water.

The advantages of removing air and gases from water in order to decrease the scale or encrustation-forming properties thereof,

are commercially recognized and appreciated, and the present invention provides an eflicient method and apparatus by means of which such deaeration may be accomplished.

It has heretofore been proposed to utilize heaters of the through or thoroughfare type, both in condensing and noncon-- densing plants. It has also been proposed to use heaters of the induction type in a sim- 'ilar manner. Each of these types of heaters is well known commercially and each is recognized as having certain desirable characteristics. I have found, however, that very advantageous results may be produced by combining the two types of heaters in such manner that they both operate on the water being treated and each modifies the action of the other.

In order to make the construction and operation of the apparatus described herein more clearly understood, it may be stated that the term thoroughfare heater as used is definitive of the type of heater, preferably of the open contact type, having an excess of steam supplied thereto over and above that required to heat the water, and in which both the heating steam and the excess steam enter the heater, and the excess then passes to other connections, the water preferably being heated by distribution inthe presence of the steam. Its characteristic, therefore, is that there is a thoroughfare flow of steam through the heating chamber and this is the only constructional limitation whlchthe designation of the heater carries w1th 1t. The term induction heater as used herein is definitive of the type of heater in which the steam is drawn thereinto by the cooling effect of the water being water in distributed condition is heated by contact with the steam. Its characteristic,

heated. Preferably, the

therefore, is an induced flow which is generally proportional to the work being done, and this is the only constructional limitation which the designation carries with it. v

The construction illustrated in the present application embodies a combination of these two types of heaters in such manner that an eflicient deaerating apparatus is provided which may be expeditiously controlled;

In my co-pending application, Serial No. 535,744, filed February 11, 1922, I have illustrated a method of treating water and apparatus therefore embodying broadly a combination of heaters. The present application constitutes certain improvements on a construction and method disclosed therein.

In the accompanying drawings, I have shown for purposes of illustration only, a preferred embodiment of the present invention, it being understood that the drawings do not definethe limits of my invention and that changes may be made in the construction and operation without departing from the spirit of my invention or scope of my broader claims.

In the drawings,

Figure 1 is a diagrammatic side elevation of one form of apparatus for carrying out the present invention; and

Figure 2 is a vertical sectional view through the apparatus illustrated in Figure 1, certain of the parts being shown in elevation.

.For purposes of a more clear understanding of the present invention it may be stated that the air content dissolved in water is partly a function of water temperature, and partly a function of air tension in the atmosphere in which the water is agitated, as for example, a heater. The minimum air tension, and therefore the ideal limit, which can be secured in a heater in which steam is the heating medium, is obviously the air tension of the incoming steam. This isalmost infinitesimal. Any process of condensation by decreasing the condensable portion of the heatin medium inevitably increases the noncondensable portion thereof, which is air.

A thoroughfare heater from the standpoint of air tension is very desirable, as it is able to approach the ideal limit referred to provided the condensation of steam which occurs therein is substantially inappreciable. From an economical standpoint, however, a thoroughfare heater is not desirable in most power plants, because the uncondensed steam which passes through the heater to other connections therebeyond is not recoverable.

An induction heater, on the contrary, operates in a different sense from a heat balance standpoint, in that virtually all of the steam coming to it is utilized, neglecting the small amount which passes therefrom through the vent as a mixture with air. The induction heater, therefore, b condensing substantially all of the con ensable portion of the vapor mixture coming to it, necessarily increases the proportion of air. This is undesirable from a standpoint of deaeration. From the heat standpoint, however, without regard to deaeration, the induction heater is much more efficient and to a large extent is the only commercially utilized heater in power plants.

I have discovered that it is possible to so combine these two ty es of heaters, that the thoroughfare heater Functions primarily for the purpose of deaeration, and the induction heater primarily for the purpose of heating the water before it passes to the thoroughfare heater. The division of work may, as will be apparent, be varied as desired. It is obvious,

however, that if the major part of the heating medium is condensed in the induction heater and the major part of the heating 1s accomplished in this heater, virtually all of the heating medium coming to the thoroughfare heater will pass through it to the induction heater. thoroughfare heater will have the advantage of the two fundamentals of high temperature with corresponding low air solubility, and low air tension substantially equivalent to that of the heating medium. Broadly, therefore, my invention combines with the high deaeration pro erties of the thoroughfare heater, the high heat conserving properties of the induction Heater, whereby very advanta eous results are accomplished.

eferring more particularly to the drawin s, there is illustrated an induction heater 2, avin an inlet connection 3 for supplylng thereto t e water to be treated. The feed of water into the induction heater is preferably regulated automatically by a float 4, operatively connected'to the valve 5 in any desired manner for cutting off the supply of water to the heater when the level therein reaches a predetermined point. The valve 5 receives water throu h a connection 6 leading fromacondenser 7 avin a cold water inlet 8. The construction an operation of the condenser will be described in detail hereinafter.

The water, after it has passed through the By reason of this condition the condenser 7 and has been heated in the induction heater 2, may flow to a thoroughfare heater 9 through a connection 10, provided with a controlling valve 11. This flow is automatically controlled by a float 12 having an 0 erative connection with the valve 11. he treated water may be withdrawn from the thoroughfare heater 9 through an outlet 13. It will be apparent that the position of the float 12 will vary in accordance with the demands upon the apparatus and thereby automatically regulate the supply of water to the apparatus. The heating medium, such as steam, may be supplied to the apparatus through a thermostatic valve 14 having operative connection with the interior of the thoroughfare heaterf This valve may be of any ordinary commercial type operating on the expansible principle and actuated either by the pressure of a volatile vapor, or the pressure of an incompressible fiuid such as mercury, the temperature of the apparatus furnishing the motive energy. The temperature element 15 of the valve is preferably located in the water storage space of the induction heater whereby the admission of the heating medium is regulated in proportion as the admission of Water to the induction heater varies the temperature therein.

It is desirable in the present apparatus to provide for deaeration at temperatures lower than atmospheric conditions which are usually 210 to 212 F. and still retain the advantages of utilizing an induction heater in combination as set forth herein and in my co-pending application referred to. The problem of such an operation, however, presents a considerable difliculty.

In accordance with the present state of the art it is customary to withdraw the exhaust steam, which is almost universally employed as heating steam for boiler feed water, from the auxiliaries which produce it at substantially atmospheric pressure. It is, however, desirable to effectuate deaeration at temperatures between 140 and 212 F. If atmospheric steam in excess is admitted to the thoroughfare heater it would he obviously impossible to maintain the desired low temperature therein, while, onthe other hand, if a deficiency only of steam is available, the pressures would drop below atmospheric and a vacuum would be produced on the valve 14 and transmitted thereby to the main supplying steam. This is a serious objection, as at the present time little reliance can be placed upon the exclusion of air from such mains, and obviously if there is a vacuum in the low 1 pressure stage steam pipe air will tend to infiltrate thereinto. With air leakage the apparatus becomes inoperative as the air tension in the thoroughfare heater would be so increased as to prevent its efiicientoperation from a deaeration standpoint as set forth herein.

the admission of steam is preferred, due to the present state of the art, it may be modified where the entire steam supply pipe is of such nature as to insure vacuum tightness.

As pointed out, this is not entirely feasible at the present time, but there is an increasing tendency to operate auxiliaries under vacuum or lowered back pressures and thereby secure the advantages of steam economy which such back pressures give. With such installations the exhaust pipe system whichconducts steam from the auxiliaries is improved to provide against any undue air infiltration. With such systems the controlling valve 14 might be eliminated, as the means for withdrawing the exhaust steam from the auxiliaries would then function as a controlling means whereby there would be maintained in the steam supply piping an efiicient pressure for the operation of the deaeration apparatus.

Since it is desirable to maintain an air tens'ion within the thoroughfare heater which is .as low as possible, the controlling means for the admission of steam, which may be in the form of a valve 14, is very important. It ads mits steam to the thoroughfare heater in exact accordance with the heating capacity required by the induction heater. As this form of controlling means may be actuated by the temperature within the induction heater, it constitutes an automatic means for preventing condensation and increase in air tension within the thoroughfare heater.

The steam admitted to the thorou hfare heater flows therethrough and by means of the connection 16 may pass into the induction heater as an induced flow determinedentirely by the work being done therein.

If it were possible in commercial practice to obtain steam for heating purposes entirely free of dissolved gases, the operation of an apparatus of this character could be greatly simplified. As this is not possible, however, it is necessary to provide a vent 17 for the induction heater for the purpose of removing non-condensable gases therefrom. It isimpossible in condensation work to secure an entirely steam free vent mixture and the vent pipe therefor conducts a mixture of steam and air. Since the induction heater is of necessity a good heating means but an imperfect condensing means, thisvent may at times carry away a very considerable portion of steam, all of which represents a loss.

In the present form of my invention 1 have I provided a condenser 7 cooperating with the vent for the purpose of recovering the heat represented by the vented steam and also condensing the same. While the condenser is preferably of the well known surface type in which there is no contact between the condensing water and the steam to be condensed, it will be apparent that it might if desired be in the form of another open heater.

Cooperating with the condenser 7 is an ejecting means 18, preferably in the form of a steam ejector for evacuating the condenser 7 It is highly desirable that the heat exchanging means comprising the induction heater, the thoroughfare heater and the condenser shall all operate under a vacuum corresponding very closely to atmospheric pres sure, minus the vapor tension of the water in the induction heater. The condenser is, therefore, very desirable as it obviates the necessity of providing an ejector having an air e ecting capacity large enough for aspirating a large quantity of steam out of the induction heater through the vent. condenser by its action secures economy in ejection capacity. If the condenser was of suflicient capacity to accomplish its duty automatically, there would be a rush of steam through the thoroughfare heater into the induction heater and thence through the vent into the condenser 7. By making the condenser of proper size, there is provided an automatic regulation in that if its heating duty is exceeded, the ejection capacity of the ejector will be automatically diminished by reason of its being overloaded with steam. It will be apparent that the value ejection capacity as used herein is rated in terms of air or non-condensable gas removal only. A reduction in ejection capacity, as referred to, will automatically lower the vacuum and increase the absolute pressure in the induction heater. As the pressure in this heater rises, the temperature will also tend to rise, and this rise in temperature will actuate the controlling valve 14 and thus automatically limit .the amount of steam which is admitted. It will be apparent that the size of the condenser with respect to the capacity. of the apparatus is important, as by using a condenser of proper capacity it constitutes an automatic regulating means. v

In a construction as illustrated, in which the induction heater is supported by the thoroughfare heater, the head of water in the induction heater is effective for delivering water to the thoroughfare heater, thereby obviating the necessity of providing a sepa- It also simseparate supports for the induction heater are The i passes intov the induction heater and flows therethrough and through the thoroughfare heater in one direction, while the heating medium enters the thoroughfare heater and flows throu h the apparatus in the opposite direction. his counter current flow is very desirable from a standpoint of efiicient heat transfer. The induction heater and its associated parts admirably cooperate with the thoroughfare heater for preventing any increase 1n the partial air tension within the thoroughfare heater. As the deaeration of a heater is partly a function of this partial air pressure, it will be apparent that this feature is highly desirable. The controlling valve 14 is also automatically operable for preventing any increase in the air tension w1th1n the thoroughfare heater. In this manner the partial air tension in the thoroughfare heater is maintained below that which obtains where it is operating singly.

Both of the heaters may have provided therein distributing and breaking up means 19 for thoroughly breaking up the water and agitating the same to increase the heat transfer efliciency.

With the present apparatus operating in such manner that the major portion of the heating is done in the induction heater before the water passes to the thoroughfare heater, the thoroughfare heater is enabled to more efliciently act on the heated water delivered thereto under the most desirable conditions for efficient deaeration. The agitation therein is also conducive to this end.

The advantages of the present invention arise from the provision of a deaeration apparatus in wh ch the conditions are controlled in such manner with respect to steam supply, water supply and air tension that highly eflicient results are insured.

- I claim:

1. In a feed water treating. apparatus, a thoroughfare heater, an induction heater for delivering heated water thereto, said induction and thoroughfare heaters having separate water and steam connections therebe-.

tween, andrmeans responsive to a function of temperature for controlling the. supply of heater for conserving the heat of the steam escaping therethrough, substantially as described.

3. In an apparatus for heating and deaerating water, a plurality of heating means in series, said heating means having an open steam flow connection therebetween and means responsive to a function of temperature for controlling the admission of all of the heating steam to the first of the heating means, substantially as described.

4. In an apparatus for heating and deaerating water, a plurality of heating means in series, having separate steam and water connections therebetween compelling a generally counter flow of steam and water, means controlling the admission of steam to the first of said heating means, there being an induced steam flow through the apparatus, and means receiving all of the steam which leaves the last of said heating means and serving to condense at least a portion thereof, substantially as described.

5. In an apparatus for heating and deaerating water, a plurality of heating means in series, and means responsive to a function of temperature for controlling the admission of steam to the first of said heating means, and means inducing a steam flow through the apparatus of such nature that the bulk of the heating is done in the second heating means of the series, substantially as described.

6. In an apparatus for heating and deaeratingwater, a plurality of heating means in series, and heat-responsive means in a subsequent heating means of the series controlling the admission of steam to the first of said heating means whereby temperature lower than atmospheric conditions may be maintained therein, substantially as described.

7. In an apparatus for heating and deaerating water, a plurality of heating means in series, means controlling the admission of steam to the first of said heating means in accordance with conditions in a succeeding heatmg means, and means for producing a water flow through the apparatus in a direction counter to the steam flow, substantially as described.

series, means controlling the admission of steam to the first of said heating means, and a closed condenser operatively connected to the outlet of the last heating means of the series producing an induced steam flow through said apparatus, said controlling means preventing any substantial condensation and increase in air tension in the first heater ofthe series, substantially as described. 9. In an apparatus for heating and deaerating water, a plurality of heating means in ser es, means controlling the admission of' steam to the first of said heating means in accordance with a function of the temperature conditions in a succeeding heating means, means producing an induced steam flow through the apparatus, means producing a Water flow through the apparatus in a direction counter to the steam flow,'and means for automatically controlling the water flow in accordance with demands upon the appa ratus, substantially as described.

10. In an apparatus for heating and deaerating water, a plurality of heating means in series, means controlling the admission of steam to the first of said heating means. means producing an induced steam flow through the apparatus, means condensing any steam escaping from the last heating means of the series, means producing a water flow through the apparatus in a direction counter to the steam flow, and means for distributing the water in each of the heating means, substantially as described.

11. In the method of treating water, the steps consisting in supplying water serially to a plurality of heating means, producing a steam flow through all of said heating means in a direction counter to the flow of water therethrough, and controlling'the supply of steam to the heating means to 'which it is first admitted to maintain a low air tension therein and insure the major portion of the heating in. a succeeding heating P means, substantially as described.

12. In the method of treating water, the steps consisting in supplying water serially to a plurality of heating means, producing a steam flow through all of said heating means in ,a direction counter;to the flow of water therethrough, and entirely controlling the supply of steam to the heating means to which it is first admitted in accordance with the temperature conditions in a subsequent heating means in said series, substantially as described.

13. In the method of treating water, the steps consisting of supplying water serially to a plurality of heating means, producing a steam flow through all of said heating means in a direction counter to the flow of water therethrough, controlling the supply of steam to the heating means to which it is first admitted, withdrawing air from said,

heating means, and controlling the air han-. dling capacity of the air withdrawing means by the heat absorbing capacity of one of said heating means, substantially as described.

14. In the method of treating water, the steps consisting-in supplying water serially to a plurality of heating means, producing a steam flow through all of said heating means in a direction counter to the flow of water therethrough, controlling the supply of steam to the heating means to which it is first admitted, inducing a steam flow through all of said heating means, and regulating said flow inducing means by the heat absorbing capacity of the final heating means in the series, substantially as described.

15. In a feed Water heater for deaeration purposes, a heater of the thoroughfare type, a heater of the induction type, said heaters being openly connected in series with separate steam and water connections, means for producing a steam fiow through the thoroughfare heater into the induction heater and a water flow in a counter direction. means controlling the water flow in accordance with demands on the thoroughfare heater, andmeans for positively withdrawing the air from the induction heater, substantially as described.

16. In a feed water heater for deaeration purposes, a heater of thethoroughfare type,

a heater of the induction type, said heaters being openly connected in series, means for producing a steam flow through the thoroughfare heater into the induction heater and a water flow in a counter direction, means for positively withdrawing the air from the induction heater, and means for automatically regulating the air ejection capacity of said last mentioned means, substantially' as described. I

17. In a feed Water heater for deaeration urposes, a heater of the thoroughfaretype, a heater of the induction type, said heaters being connected in series, means for producing a'steam flow through the thoroughfare heater into the induction heater and a water flow in a counter direction, said induction heater being vented, and means for recoverin the heat of the steam escaping through sald vent, substantially as described.

18. In a feed water heater for deaeration purposes, a heater of the thoroughfare type, a heater ofthe induction type, said heaters being connected in series, means for producing a steam flow through the thoroughfare heater into the inductionheater and a Water flow in a counter direction, said induction heater being vented, and means for recovering the heat of the steam escaping through said vent, said last mentioned means automatically maintaining the desired pressure conditions within the heater, substantially as described.

19. In a feed water heater, a thoroughfare heater, a vented induction heater operatively connected thereto to carry the non-condensible gases through the thoroughfare heater with the steam flow whereby they i plying cold water to the induction heater for partially heating the same before it is supplied to the thoroughfare heater, and means controlling the admission of all of the heating steam to the thoroughfare heater in accordance with the temperature of the water in the cordance with the temperature of the water in the induction heater, said controlling means preventing condensation of steam in the thoroughfare heater and increase of air tension therein, substantially as described.

22. In a feed water heater, a thoroughfare heater, an induction heater operatively connected thereto for inducing the steam flow through the thoroughfare heater, means for positively withdrawing the non-condensible ases from the induction heater, and means.

or automatically regulating the air ejection capacity of said withdrawing-means, substantially as described.

23. In the method of deaerating liquids, the steps consisting of delivering liquid to a heating compartment, maintaining a characteristic atmosphere therein high in air, venting a mixture therefrom, recovering the heat of the vented mixture, delivering the said liquid to a second heating compartment, and maintaining a characteristic atmosphere in the second heating compartment low in air, substantially as described.

24. Deaerating apparatus, comprising a heating tray section and deaerating tray sec-v tion, connections for supplying liquid first to said heating tray section and thence to said deaerating tray section, connections for supplying all of the heating steam first to said deaerating tray section and thence to said heating tray section, and means for controlling the supply of steam, substantially as described.

25. Deaerating apparatus, comprising a heating tray section, a deaerating tray section, connections for supplying liquid first to said heating tray section and thence to said deaerating tray section, connections for supplying allof the heating steam-first to said deaerating tray section and thence to said heating tray section, and a condenser communicating with the heating traysection, substantially as described. I

'26. Deaerating apparatus, comprising a heating tray section, a deaerating tray section, connections for supplying liquid first to said heating tray section and thence to said deaerating tray section, connections for supplying all of the heating steam first to said deaerating tray section and thence to said heating tray section, and means for produccordance with a function of the temperature conditions in a subsequent heating compartment of the series, substantially as described.

28. In the method of deaerating liquids, the steps consisting of delivering the liquid successively to a plurality of compartments in series, continuously performing the major portion of a heating duty in one of said compartments, constantly maintaining in both of said compartments different characteris- I tic atmospheres, venting the compartment in which the major portion of the heating duty is performed, and recovering the heat of the gases vented from the last heater of said series.

29. In the method of deaerating liquids, the steps consistin of delivering the liquid successively to a p urality. of compartments in series, continuously performing the major portion. of a heating duty in one of said compartments, constantly maintaining in both of said compartments different characteristic atmospheres, venting the compartment in which the major portion of the heating duty is performed and recovering the heat of the vented gases and supplying it to the liquid to be deaerated, substantially as described.

30. In the method of deaerating liquids, the steps consisting of delivering the liquid successively to a plurality of heating compartments connected in series, controlling the supply of the liquid in accordance with demands for deaerated liquid, continuously perform-- ing the major portion ofthe heating in one of said compartments, venting the compartment in which the major portion of the heating duty is performed, and recovering the heat of the gases escapin through said vent, substantially as described.

31. In the method of deaerating liquids, the steps consisting of delivering the liquid successively to a plurality of heating compartments connected in series, controlling the supply of the liquid in accordancewith de-' mands for deaerated liquid, continuously performing the major portion of the heating in one of said compartments, venting the compartment in which the major portion of the heating duty is performed," and recovering the heat of the gases escaping and supplying the same to the liquid to be deaerated, sub

let, means for feeding Water to said heater, means controlling the steam supply through said inlet to prevent increase in air tension therein, and heating means inducing a flow through the thoroughfare heater of substantially all of the steam supplied thereto, said .heating means and thoroughfare heater being sufliciently separated to prevent back-' \vard diffusion of the air-rich atmosphere of the heating means into the air-lean atmosphere of the thoroughfare heater, substantially as described;

33. In a feed water heater, a thoroughfare heater having a steam inlet and a steam outlet, an induction heater for feeding heated Water to said thoroughfare heater, said heater being sufficiently separated to prevent the airrich atmosphere of the induction heater from contaminating the air-lean atmosphere of the thoroughfare heater, and means controlling the steam supply to said thoroughfare heater through said inlet to prevent increase in air tension therein, said induction heater inducing a flow through the thoroughfare heater of substantially all of the steam supplied thereto.

34. A deaerating apparatus comprising a temperature stage of water treatment and a pressure stage of. water treatment, said temperature stage including an induction heater and vent condenser and said pressure stage including a thoroughfare heater, and means constituting a separation between said stages effective for preventing contamination of the atmosphere in the pressure stage by the atmosphere in the temperature stage.

35. A deaerating apparatus comprising a temperature stage of water treatment and a pressure stage of water treatment, said temperature stage including an induction heater and vent condenser and said pressure stage including a thoroughfare heater, means constituting a separation between said stages effective for preventing contamination of the atmosphere in the pressure stage by the atmosphere in the temperature stage, and means including breaking up devices for the water for delivering Water successively to said stages in the order named.

36. A deaerating apparatus comprising a temperature stage of water treatment and a pressure stage of water treatment, said temperature stage including an induction heater and vent condenser and said pressure stage including a thoroughfare heater, means constitutin a separation between said stages effective or preventing contamination of the atmosphere in the pressure stage by the atheater having a steam inlet and a steam outlet, means for feeding Water to said heater, means controlling the entire steam supply to said heater through said inlet to prevent increase in air tension therein, and means continuously inducing a flow through the heater of substantially all of the steam supplied thereto.

38. In a deaerator, a temperature stage, a pressure stage, said stages being sufficiently separated to prevent the atmosphere of the temperature stage from contaminating the atmosphere of the pressure stage, means for supplying heating steam first to'the pressure stage and then to the temperature stage, means for supplying Water to the temperature stage and then to the pressure stage, and a vent condenser cooperating directly With the temperature stage and recovering the heat of the mixture vented therefrom.

In testimony whereof I have hereunto set In hand.

y JOHN R. MoDERMET.

mosphere in the temperature stage, and means including breaking up devices for the Water for delivering Water successively to said stages in the order named in such manner as to secure intimate contact between the atmosphere in said heaters .and the water supplied.

37.. In a feed water heater, a thoroughfare

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