US3417736A - Deaerating heater - Google Patents

Description

Dec. 24, 1968 A. J. SORIENTE DEAERATING HEATER Filed April 28, 1967 United States Patent 3,417,736 DEAERATHNG HEATER Alfonse I. Soriente, Gillette, N.J., assignor to Union Tank Car Company, Chicago, Ill., a corporation of New Jerse y Filed Apr. 28, 1967, Ser. No. 634,541

5 Claims. (Cl. 122-406) ABSTRACT OF THE DISCLOSURE A deaerating feedwater heater for use in a steam system employing a once-through steam generator. An integral centrifugal steam separator is provided within the heater to remove much of the kinetic energy from a flashing steam-water mixture used during startup, thus preventing internal heater damage.

SPECIFICATION Backgr0undsummary-drawing This invention relates to a deaerating heater, and more particularly to a deaerating heater having integral apparatus which prevents internal heater damage due to high kinetic energy steam.

Conventional deaerating feedwater heaters for use in steam generating systems typically employ a counter-current flow of steam condensate and steam. The steam heats the condensate and removes entrapped gases therefrom as a result of the counter-flow. Normally, since the entering steam is dry and has a relatively low kinetic energy, it will not damage the internal structure of the heater, which may include an array of deaerating and distribution trays. The steam used in the deaerating heater is typically bled from a point downstream of the steam generating apparatus in the steam system.

In once-through steam systems, however, the startup process results in the initial generation of a steam-water mixture. Since once-through boilers do not employ a steam separator, and since the turbines or other steam utilizing apparatus in such a system typically cannot accept a steam-water mixture, the mixture must be shunted around the turbines until the system begins generating dry steam. An advantageous use for this wet startup steam is in a deaerating heater which conditiOns steam condensate for re-use in the steam generating apparatus.

One conventional type of deaerating heater which may be used in a once-through system employs counter-current flow of steam and steam condensate. A typical heater of this type employs an array of trays for heating, distribution and deaerating of the condensate. During normal operation, dry steam will be bled from a point downstream of the steam generating apparatus for use in the deaerating heater. However, during startup, the incoming steam is not dry, but rather is a flashing steam-water mixture possessing very high kinetic energy. The use of such startup steam in a deaerating heater of the type described has resulted in damage to the internal heater structure due to to the high kinetic energy of the steam. Prior attempts to avoid such damage by the use of battle means have met with only moderate success, and costly damage has continued to occur.

To overcome the problem of heater damage from high kinetic energy startup steam, the present invention provides a deaerating heater with an integral steam separator positioned within the steam inlet zone of the heater itself. During startup, incoming wetsteam is directed to the steam separator where the steam and water are separated. The steam then proceeds through the heater in the conventional manner, while the separated water mingles with the conditioned steam condensate. The separation of the water 3,417,736 Patented Dec. 24, 1968 from the incoming startup steam results in a significant reduction in the kinetic energy of the steam-water mixture, most of the energy being absorbed by the separator. Thus the problem of damage is effectively overcome.

The invention will be more fully understood by considering the following description, with illustrative reference to the drawing, in which there is shown a side sectional view of an exemplary deaerating heater construction embodying the present invention.

Description of exemplary embodiment With reference to the drawing, there is shown an eX- emplary deaerating heater 10, which is preferably of the type described in US. Patent No. 3,241,105, issued Dec. 1.3, 1966. The heater 10 comprises a cylindrical tank 12 having curved end portions 14 and 16. The tank 12 is mounted upon a feedwater storage tank 18 by saddle supports 20 (only one shown). The heater tank 12 and the storage tank 18 are connected by a storage conduit 22 and by a pair of pressure equalization lines 24 and 26.

The interior of the heater tank 12 is partitioned into a number of zones, including a steam inlet zone 28, a condensate collecting zone 30, a deaerating zone 32, an internal vent condenser 34 and a condensate manifold 36. The condensate manifold 36 is defined by a curved wall 38 which is joined to the interior of the tank 12, and by end walls 40 and 42. An inlet conduit 44 communicates with the condensate manifold 36. Mounted in the condensate manifold 36 in association with the mouth of the inlet conduit 44 is a deflector plate 46 which is attached to the tank 12 by suitable supporting members 48. A plurality of spray nozzles 50 are mounted in the curved partition 38 and serve to transmit steam condendensate from the condensate manifold 36 to the internal vent condenser 34.

The internal vent condenser 34 is defined by a side partion 52, and by the end walls 40 and 42. The side partition 52 is joined at its upper end to the curved partition 38. A plurality of vents 54 are provided to vent the condenser 34 to atmosphere.

The deaerating zone 32 is define-d by a frame 56, the end walls 40 and 42, and the side partition 52. The frame 56 rests upon a plurality of I-beam supports 58 which are in turn supported by a half-channel member 60 which is secured to the inner wall of the tank 12. At the left end of the deaerating zone 32 is a hemispherical enclosure 62 which communicates with the interior of the deaerating zone defined by the end walls 4% and 42 and the side partition 52.

Disposed within the deaerating zone 32 is an array of shallow deaerating trays 64 which are suitably supported by the frame 56. The trays 64 are aligned substantially parallel to the longitudinal axis of the tank 12. Above the frame 56, at the boundary between the deaerating zone 32 and the internal vent condenser 34, is a plurality of heating and distribution trays 66 which are aligned at substantially right angles to the longitudinal axis of the tank 12.

Mounted in the end portion 16 of the tank 12 is a conventional manway 68 which communicates with the interior of the tank. Mounted between the end portion 16 and the hemispherical enclosure 62 is an inspection platform 70. An access door 72 is provided in the end wall 42 for access to the interior of the internal vent condenser 34.

The steam inlet zone 28 is at the right-hand end of the tank 12 and is defined by the end portion 14 and the end wall 40. Entering the steam inlet zone 28 through the end portion 14 is a dry steam conduit 74 which has associated therewith a baffle 76. Also entering the steam inlet zone 28 is a startup steam conduit 78 connected to an external steam manifold 80. Communicating with the manifold valve 84.

Mounted within the steam inlet zone 28 is a steam separator 86. The separator 86 is a cylindrical shell having its open ends 88 and 90 substantially vertically aligned. Secured to the inner surface of the separator 86 near the open end 88 is an internal annular water baffle 92. Slightly below the baflie 92 in the wall of the separator 86 is an elliptical port 94. The conduit 78 is tangentially attached to the outer shell of the separator 86 so as to communicate with the port 94.

The condensate collecting zone is defined by the bottom of the tank 12 and by the lower portion of the frame 56. A screen 96 is disposed over the mouth of the storage conduit 22 in the collecting zone 30, and the pressure equalizer lines 24 and 26 are provided with baffles 98 and 100, respectively.

As indicated above, during operation of the deaerating heater 18 steam condensate coming from a condenser which is downstream of the steam utilizing apparatus in a once-through steam system enters the condensate manifold 36 of the tank 12 through the inlet conduit 44. The incoming condensate flow is dispersed in the manifold 36 by the deflector plate 46. During normal operation of the steam system, dry steam enters the steam inlet zone 28 of the tank 12 through the conduit 74 and strikes the steam bathe 76, whence it is dispersed throughout the steam inlet zone.

The steam condensate in the manifold 36 is sprayed into the internal vent condenser 34 through the nozzles The trays 66 serve to collect the condensate and distribute it evenly across the top of the deaerating zone 32. The condensate flows downwardly from the trays 66 through the array of deaerating trays 64 in attenuated streams. The trays 64 cause further attenuation of the condensate flow through the deaerating zone 32, so that the downward flow of condensate ultimately is in thin sheets or streams. The condensate ultimately flows out of the bottom of the deaerating zone 32 and into the condensate collecting zone 30 and finally through the storage conduit 22 to the storage tank 18 where it is available for reuse in the steam generating apparatus. The screen 96 prevents foreign material from passing through the conduit 22 into the storage tank 18, and the batfies 98 and 108, associated respectively with the pressure equalization lines 24 and 26, prevent condensate from passing through the lines into the storage tank 18.

The dry steam in the steam inlet zone 28 passes into the deaerating zone 32 through suitable apertures in the end wall 40. Preferably, the apertures in the wall 40 are confined to the lower portion of the wall so that the dry steam enters the lower portion only of the deaerating zone 32. The deaerating trays 64 form sinuous passages for the dry steam through the deaerating zone 32. In addition, the hemispherical enclosure 62 provides a directional means whereby the dry steam may he made to pass through the deaerating zone 32 more than once. Ultimately, the dry steam passes through the uppermost portion of the deaerating zone 32 and into the internal vent condenser 34. The incoming condensate being sprayed into the condenser 34 cools and condenses the steam and becomes heated in this manner. The condensed liquid passes downwardly through the deaerating zone 32 along with the incoming steam condensate, while the non-condensa-ble gases in the steam are passed to atmosphere through the vents 54. The intimate contact of the dry steam with the thin streams or sheets of condensate in the deaerating zone 32 results in the removal of entrapped gases from the condensate.

During startup, however, there is no source of dry steam for use in the deaerating heater 10. Accordingly, it is necessary for the heater 10 to accept a flashing steam water mixture from a flash tank or other apparatus (not shown) associated with the steam generating apparatus. This flashing wet steam is routed to the steam manifold through the conduits 82 which are controlled by the valves 84. The flashing steam-water mixture is then communicated to the steam separator 86 in the steam inlet zone 28 through the conduit 78. Because the conduit 78 is connected to the separator 86 tangentially, the incoming flashing steam-water mixture tends to pursue a circumferential course within the separator 86. This action, of course, results in centrifugal force, which has the effect of separating the steam-water mixture by causing the heavier liquid phase to move to the wall of the separator 86. The force of gravity causes the separated water to flow downwardly out of the bottom of the separator 86, while the separated and now dry steam rises upwardly through the top 88 of the separator. The water exiting through the bottom 90 is collected in the condensate collecting zone 30 while the steam exiting upwardly through the top 88 flows through the deaerating zone 32, etc., as described above. The annular baffie 92 prevents water from being forced upwardly along the inner surface of the separator 86 and out the top 88.

Although the separator 86 results in separating the liquid and gas phases of the incoming startup steam, the principal benefit produced by the separator is a significant reduction in the kinetic energy of the incoming steam- Water mixture. This mixture possesses kinetic energy which is often beyond the ability of such structural components as the trays 64 and 66 to withstand, thus causing damage to those components. However, during the separation of the mixture in the separator 86, a great deal of this kinetic energy is absorbed by the separator and converted to the centrifugal force which accomplishes the separation process. Thus, the separated steam exiting through the top 88 of the separator 86 is of sufficiently low kinetic energy that it causes no damage to the internal structure of the heater it Of course, other types of steam separator might be employed, but a centrifugal separator has been found to achieve a significant reduction in kinetic energy of the startup steam. Moreover, a centrifugal separator of the type shown in the drawing is simply constructed at low cost, and can be readily and inexpensively installed in existing heaters.

Although an embodiment constructed in accordance with the present invention has been described with the requisite particularity, the disclosure is of course only exemplary. Consequently, numerous changes in details of construction, in size, configuration and arrangement of components and materials, and in modes of application will be apparent to those familiar with the art and may be resorted to without departing from the scope of the invention as set forth in the following claims.

I claim:

1. A deaerating heater for steam condensate adapted to use Wet steam during startup and dry steam thereafter, said heater comprising: a tank having a steam inlet zone, a deaerating zone, and a condensing zone; spray means for spraying condensate into said condensing zone; distribution means for distributing condensate from said condensing zone into said deaerating zone; means for intimately contacting said condensate with steam in said deaerating zone; a first steam inlet for admitting dry steam to said steam inlet zone; a second steam inlet for admitting wet steam to said steam inlet zone during startup; and a steam separator in said inlet zone communicating with said second steam inlet for separating the liquid phase from said wet steam.

2. The deaerating heater as defined in claim 1 wherein said steam separator is a centrifugal separator.

3. The deaerating heater as defined in claim 2 wherein said separator comprises a substantially vertical cylinder having an inlet port, said second steam inlet communicating with said port such that said wet steam enters said cylinder essentially horizontally and essentialy tangentially to the inner surface of said cylinder.

4. The deaerating heater as defined in claim 3 wherein said separator further includes an internal, annular water bafile above said port.

5. A deaerating heater for steam condensate adapted to use Wet steam during startup and dry steam thereafter, said heater comprising: a tank having a steam inlet zone, a deaerating zone, and a condensing zone; spray means for spraying condensate into said condensing zone; distribution means for distributing condensate from said condensing zone into said deaerating zone; deaerating means in said deaerating zone defining sinuous passages for steam through said zone and defining attenuated condensate streams through said zone; a first steam inlet for admitting dry steam to said steam inlet zone; a second steam inlet for admitting wet steam to said steam inlet zone during startup; and a steam separator in said inlet zone communicating with said second steam inlet, said steam separator including a substantially vertical 'cylinder having an inlet port, and wherein said second steam inlet communicates with said port such that said Wet steam enters said cylinder essentially horizontally and essentially tangentially to the inner surface of said cylinder.

References Cited UNITED STATES PATENTS 2,762,451 9/1956 McNeil 55-204 3,291,105 12/1966 Stenard 122406 KENNETH W. SPRAGUE, Primary Examiner.

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