US2490294A

US2490294A - Deaerating heater

Info

Publication number: US2490294A
Application number: US625006A
Authority: US
Inventors: Bergquist Carl Hugo
Original assignee: Elliott Co
Current assignee: Elliott Co
Priority date: 1945-10-27
Filing date: 1945-10-27
Publication date: 1949-12-06
Anticipated expiration: 1966-12-06

Description

Dec. 6, 1949 c. H. BERGQUIST 2,490,294

DEAERATING HEATER Filed Oct. 27, 1945 INVENTOR WITNESSES:

ATTORNEYS.

Patented Dec. 6, 1949 DEAERATING HEATER,

Carl Hugo Bergquist, Forest Hills, Pa., assignor to Elliott Company, Jeannette, Pa., a corporation of Pennsylvania Application October 27, 1945, Serial No. 625,006

3 Claims. 1

This invention relates to apparatus for heating and deaerating boiler feedwater by means of steam, and more particularly to such apparatus in which the steam enters the deaerating tank through a nozzle at high velocity.

In order to deaerate boiler feedwater it may be heated by steam in a deaerating tank, and, as the temperature of the water approaches the saturation temperature, the solubility in the water of such gases as oxygen and carbon dioxide approaches zero. These non-condensible gases therefore are liberated from the water and are swept to the vent of the deaerating tank by the flow of steam.

In some deaerators the incoming steam is sprayed from nozzles into the water to atomize the water in order to promote heating and deaeration. When such deaerators are operated at light loads the water is allowed to enter the outlet of the steam nozzle and flow backwardly into the nozzle where it forms an obstruction that holds back the steam until sufiicient steam pressure is built up to blow this body of water out of the nozzle. The steam and water therefore leave the nozzle in intermittent bursts. It is obvious that good atomization and deaeration can not be obtained in this way.

There are other deaerators in which the feedwater enters the steam nozzle some distance behind its outlet, and the water and steam are mixed together in the nozzle. To produce good mixing at high as well as low loads, it has been proposed to automatically vary the size of the nozzle in accordance with the load, but this involves the use of moving parts inside the tank where they are diflicult to service in case they get out of order. It also increases the cost of the deaerating apparatus considerably.

It is among the objects of this invention to provide an inexpensive deaerating heater in which a spray of steam thoroughly and continuously mixes with the water being heated by it, in which the water can not run back into the steam nozzle from its outlet, and in which thorough mixing of steam and water occurs at all loads without the use of moving parts.

In accordance with this invention water to be heated and deaerated is introduced into a deaerating tank having a vent through which escape the non-condensible gases liberated from the water. The tank is also provided with a steam inlet to which is connected a combined mixing and atomizing nozzle that has an outlet preferably located near the center of the tank. One wall of the nozzle is provided with an inlet opening for water which is conducted to it from the area where it enters the tank. Inside the nozzle, between its outlet and the water inlet, there is a transverse scrubber plate against which steam projects water that enters the nozzle through the water opening, thereby producing turbulence and thorough mixing of the steam and water before it leaves the nozzle. The nozzle has an elevated portion between its outlet and the water inlet to keep water outside the nozzle from flowing over the upper edge of the outlet unless the water rises above the elevated portion. In such a case any water flowing over the upper edge of the outlet is atomized by the steam and water mixture discharged from the nozzle outlet, so that the water can not flow back into the nozzle from its outer end. This nozzle therefore produces continuous, thorough mixing of steam and water at any load.

The preferred embodiment of the invention is illustrated in the accompanying drawings in which Fig. 1 is a vertical section through my deaerating heater; Fig. 2 is a similar section of the heater, partly in elevation, taken on the line IIII of Fig. 1; and Fig. 3 is a horizontal section taken on the line III- II of Fig. 1.

Referring to the drawings, relatively cold boiler feedwater enters one side of the upper end of a deaerating tank I and is conducted diametrically across it through a horizontal spray pipe 2. This pipe may be provided with two parallel rows of closely spaced jets 3 extending along it for supplying the water in two sheets upwardly and outwardly in opposite directions against straight and cylindrical baiiles. The cylindrical baflle 4 extends downwardly a short distance from the top of the tank aroundthe two spaced pairs of parallel straight baflles 6 and I that likewise are secured to the top of the tank. The upper wall of the spray pipe between the two rows of jets may be made flat to avoid water hammer and may be covered by a fiat plate 8 that projects a short distance laterally from the pipe to control the upper sides of the two sheets of water so that they will not spray up into the vent that will be described later. The sprayed water flows from the baffles down into a vertical cylinder 9 which encircles the lower end of the cylindrical bafl'le and is spaced from it and the side of the tank. The cylinder may be supported from the side of the tank by circumferentially spaced members ll. This cylinder forms the side wall of a pan the bottom wall l2 of which is inclined in order to form a drain member.

The center of the top of the tank is provided with an opening in which a short vertical vent pipe I3 is mounted. The lower end of this pipe communicates with the top of a narrow gas-receiving hood 14 extending horizontally across the tank directly above the spray pipe to which it is parallel. The bottom of this receiver or hood is provided with a long rectangular opening which forms the entrance to the vent. The lower side edges of the hood, which form opposite sides of the vent entrance, are so positioned relative to the spray jets in the pipe that the sheets of water issuing therefrom flow outwardly across those edges and thereby form a water curtain that closes the entrance to the vent. To equalize the pressure drop along the length of the hood a horizontal baiile plate i6 is mounted inside the hood with its sides spaced therefrom. This vent construction is part of the subject matter of my copending application Serial No. 608,999, filed August 4, 1945, now Patent No. 2,452,716 in which its construction and operation are described. It is unnecessary in this specification to go into a description of the vent any further than to point out that the non-condensible gases liberated from the heated water escape through the vent without the loss of an appreciable amount of steam. A cont-.ibuting factor to this highly desirable result is a pressure control valve I! that is mounted on top of the vent pipe. As the construction and operation of this valve form no part of the present invention, further description of it will not be given herein. It is fully described in my copending application. The side of the tank may be provided with a normally closed access opening l8.

In order to heat the water in the tank, steam is sprayed into the water. This is done by providing the upper portion of the side wall of the tank with a steam inlet 20 to which a nozzle is connected inside the tank. The nozzle preferably has a vertical section 2| extending downwardly from the steam inlet with the side wall of the tank forming one side of the nozzle. The upper portion of the nozzle'projects into the adjoining deep side of the pan formed by cylinder 9 and drain member l2. At the lower end of vertical section 2| the nozzle turns and extends inwardly and upwardly to approximately the center of the tank, thereby forming an inclined nozzle section 22. The upper end of this inclined section is spaced below the pan and is provided with an outlet 23 that opens laterally; that is, the upper wall of the outlet is substantially horizontal so that vapor issuing from the nozzle is directed more or less horizontally across the tank to prevent it from being blown directly up into the space between the pan and the tank. The opposite sides of the nozzle are formed from vertical plates 24 that also extend upwardly from the inclined section to the bottom of inclined drain member I! to which they are welded. Thus, a chamber is formed directly above the inclined section of the nozzle. Water issuing from spray pipe 2 collects in the pan from which it is discharged into this chamber through a rectangular opening 26 in the lower end of drain member l2. This member also may be provided with an access opening 21 that is closed by a door plate 28 bolted in place.

Feedwater sprayed from pipe 2 against the baflles attached to the top of the tank is heated preliminarily by uncondensed steam that has risen into the top of the tank. This water falls into the pan below the bailles and is discharged through opening 26 into the water-collecting chamber formed on top of inclined section 22 of the steam nozzle. The lower wall of this chamber, which is the upper wall of the inclined section of the nozzle, is provided near its lower end with a transversely extending slot 30 that forms an inlet passage for water into the nozzle from the chamber above. The shape of the inclined section of the nozzle in vertical section preferably is somewhat like a venturi so that steam passing upwardly through it past the slot at high velocity will have an iniector effect that will draw the water through the slot into the nozzle. A large head of water to force the water through the slot is unnecessary.

Inside the nozzle between this water inlet Ill and the outlet of the nozzle there is a baifle plate 3| extending across the nozzle to the lower wall of which it is secured. The top of this plate is only a short distance below the upper wall of the nozzle, so that a restricted port 32 is formed between them. This plate forms a scrubber against which the steam projects water that has entered through slot 30. By the time the water has splashed against the plate and then been forced by the steam through narrow port 32, the water is thoroughly broken up and mixed with the steam. This occurs even at very light loads when, in the absence of the scrubber plate, water might periodically collect in the lower end of the nozzle and then be blown out as a slug. The entrained water in my deaerator is heated efliciently by the steam, and non-condensible gases are liberated from the water as it enters the lower pressure area below the pan. The hot water falls into the bottom of the tank which serves as a reservoir from which feedwater is pumped out through outlet 33.

Under light loads all of the water discharged from the pan will enter the nozzle through the water inlet slot 30. However, under heavy loads there may be so much water pouring from the pan into the collecting chamber below it that the steam will not be able to draw it through inlet 30 fast enough to prevent the water from rising in the chamber high enough to escape from it by overflowing the outlet end of the nozzle. In such a case, water that flows over the upper edge of the nozzle will be caught by the high velocity stream of mixed steam and water issuing from the nozzle and will be atomized by it. The atomized water is quickly heated by the steam.

The overflow from the water-collecting chamber is at a level slightly below the bottom of steam inlet 20 so that if the steam is shut oil! water can not rise high enough in the vertical section of the nozzle to run back into the steam conduit.

In a deaerating heater constructed in accordance with this invention there is continuous and thorough mixing of steam and water at all loads without the use of moving parts to compensate for changes in load, and without a large head of water inside the tank which wouldtake up space needed for the storage of the heated and deacrated water. At some loads the nozzle will serve only as a scrubber nozzle because no water will flow over the upper edge of its outlet. At higher loads, the only time when water overflows the water-collecting chamber and falls into the spray issuing from the nozzle, the nozzle will function also as an atomizing nozzle. Therefore, regardless of load, all of the water will be broken up into a finely divided state and thoroughly mixed with the steam. At no time can water be blown out of the nozzle by the steam without satisiactorily mixing with it.

According to the provisions of the patent statutes, I have explained the principle and construction of my invention and have illustrated and described what I now consider to represent its bestembodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

' 1. A deaerating heater comprising a deaerating tank having a vent for escape of non-condensible gases, means for spraying water inside the tank, the tank also being provided at one side with an inlet tor steam, a combined mixing and atomizing nozzle in the tank connected to said steam inlet and having a portion extending downwardly from the inlet and another portion inclined upwardly from said first portion and terminating in an outlet near the center of the tank, the upper wall of said inclined portion being provided near its lower end with an inlet opening for water, substantially parallel side wall members closing the space between said upper wall and said downwardly extending portion of the nozzle and rising above said outlet, and a pan mounted in the tank for collecting water sprayed from said means, the bottom of the pan being spaced above the nozzle outlet and being inclined downwardly toward said downwardly extending portion of the nozzle, said pan bottom engaging the tops of said side wall members and being provided with an opening between said members for emptying said water into the space between them, any water rising high enough between said side wall members to flow over the upper edge oi. said outlet being atomized by the steam and water mixture discharged from the nozzle outlet.

2. A deaerating heater comprising a deaerating tank having a vent for escape of non-condensible gases, means for delivering water to the tank, the tankalso being provided with an inlet for steam, a combined mixing and atomizing nozing to produce thorough mixing, said plate forming in the nozzle a restricted port through which the steam will carry the water at high velocity.

3. A deaerating heater comprising a deaerating tank having a vent for-escape of non-condensible gases, means for spraying water inside the tank, the tank also being provided at one side with an inlet for steam, a combined mixing and atomizing nozzle in the tank connected to said steam inlet and having a portion extending downwardly from the inlet and another portion "ining substantially Venturi-shape to form a threat at said inlet opening for reducing the steam pressure at that point so that water can enter the nozzle through said opening, and a transverse scrubber plate in the nozzle between its outlet and said opening and against which said steam projects water -fromsaid opening to produce thorough mixing, said plate forming in the nozzle a restricted port through which the steam will carry the water at high velocity, any water rising high enough in said chamber to escape through said overflow flows over the upper edge of the nozzle outlet and is atomized by the'steam and water mixture discharged therefrom at high velocity.

CARL HUGO BERGQUIBT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS