US3301538A - Direct contact heat exchangers - Google Patents

Description

Jan. 31, w H, G|BSON DIRECT CONTACT HEAT EXCHANGERS Original Filed Aug. 29, 1963 United States Patent 3,301,538 DIRECT CONTACT HEAT EXCHANGERS William H. Gibson, Newcastle-upon-Tyne, England, assignor to C. A. Parsons & Company, Limited, Newcastle-upon-Tyne, England, a corporation of Great Britain Continuation of application Ser. No. 305,494, Aug. 29, 1963. This application June 30, 1966, Ser. No. 562,000 Claims priority, application Great Britain, Sept. 25, 1962, 36,432/62 3 Claims. (Cl. 261-111) This application is a continuation of application Serial No. 305,494, filed August 29, 1963, and now abandoned.

This invention relates to heat exchangers in which there is direct contact between a fluid in the form of a gas or vapor and another fluid in the form of a liquid. It is particularly, though not exclusively, applicable to direct contact boiler feed water heaters and to condensers such as are used in steam turbine plants.

It is customary in heat exchangers of the kind stated in the first paragraph of this specification to atomize the liquidto form small droplets so that the liquid as presented to the gas or vapor has a large surface area in relation to its volume. In .this way a highly eflicient heat exchange process is achieved, and in addition the size of the vessel in which the process takes place is kept to a minimum.

Atomization of the liquid is usually achieved by means of nozzles wherein swirling motion is imparted to the liquid. The liquid issuing from the nozzle is in the form of a cone shaped film which, at some distance from the nozzle, breaks down into the form of droplets due to the forces of surface tension.

A disadvantage of such heat exchangers is that the size of the vessel is to some extent determined by the spacing of the nozzles used to atomize the liquid, as they must be spaced sufficiently apart to avoid excessive interference between the conical films formed by adjacent nozzles. If substantial interference is allowed to take place droplets of large size may be formed from interfering films, and the efiiciency of heat transfer may be impaired.

A further disadvantage arises from the fact that a considerable part of the heat transfer occurs when the liquid is in the film phase before breaking into droplets, and with conical films of liquid a flow of gas or vapor cannot reach the inside surface of the film easily.

Another disadvantage is that appreciable pumping power has to be expended to force the liquid through the nozzles and achieve droplets of sufficiently small size to complete the heat transfer in the space of the vessel available.

The general object of the present invention is to provide a heat exchanger of the kind described in the first paragraph hereof in which the above disadvantages are substantially overcome or their eflects reduced.

Other objects and advantages of the invention which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is a side view in section of a direct contact boiler feed water heater in accordance with one form of the present invention;

FIG. 2 is a section on line IIII of FIG. 1; and

FIG. 3 is an enlarged view of a water pipe and associated deflector plates.

In carrying the invention into effect in the form illustrated 'by way of example and referring to FIGS. 1 and 2 a direct contact boiler feed water heater comprises a vessel or casing 1. Passing through one end of the casing is "ice a pipe 2 which extends axially along the heater. Projecting from the pipe 2 are branch pipes 3 and these in turn have apertures 4 (see FIG. 3) from which water emanates. Opposite each aperture 4 is a deflector plate 5.

The deflector plates are spaced at different distances from the apertures 4 of a given row in a branch pipe.

They are also spaced from each other in the direction of the axis of the branch pipes. The plates are positioned so that each film of water lies in a different plane and does not interfere with adjacent films. While in the form shown each deflector plate of a branch pipe is at a different distance from the branch pipe this may not be necessary if the branch pipe is long, and the spacing of the apertures is such that the deflector plate of say every fourth aperture may be at the same distance from the branch pipe. The important criterion is that preferably no two films should substantially interefere. In FIG. 2 the outlines of the films are indicated by dotted lines.

The deflector plates which are preferably, but not essentially, flat plates may be attached individually or as a cluster to the branch'pipes by any suitable means, such as tack welding to the pipes.

Steam enters the heater through inlets 6 and is dispersed over the length of the heater by perforated baffle plate 7. The steam then flows downward between the water films reaching all surfaces of the films with equal ease. densed steam and feed water injected through the pipe 3 collect in space 8 after passing through perforated baflle plate 9 and are conducted from the heater through outlet 10.

Vapor or gas not absorbed by the liquid or released by the liquid during the heat transfer process may be removed by the vent pipe 11.

While the invention has been described with particular reference to direct contact boiler feed water heaters it can also be applied to condensers and to any heat exchanger in which direct contact takes place between a gas or vapor and a liquid. In other arrangements of heaters the steam may be arranged to flow upwards with the gas or vapor vent being provided at the highest point of the vessel.

With the arrangement described the size of the heat exchanger vessel is not governed to such a great extent by nozzle spacing as in previously known heat exchangers of this kind. The liquid issues in the form of thin flat films instead of conical films, and as a consequence the volume of the heat exchanger vessel can be reduced.

As mentioned above the steam, vapor or gas can reach both surfaces of each liquid film with equal ease, and this means that for a given rate of flow of liquid and gas or vapor equal efliciency of heat transfer can be achieved either with a vessel of smaller volume than in the case with conical sprays or a vessel of the same size can be used with a reduced pumping power requirement.

In general the jet of water issuing from an aperture is directed at an angle to a deflector plate, a typical angle between the jet and the plate being 30. This angle can, however, be varied to suit circumstances.

The spacing between deflector plates will also depend upon circumstances but in general it will not be less than 0.75" in order to allow for errors in the setting up of the plates. Regarding the width of the plates this is governed by the size of the aperture through which the water issues, and as a general guide the width of the deflector plate should be at least four times the width of the liquid jet. Where relatively wide plates are employed, their horizontal supporting members prefer-ably should be perforated or otherwise cut down so as not to offer any substantial obstruction to the access of vapor or gas to the inside surfaces of the liquid films or sprays, as viewed for instance in FIG. 3.

Con-

Having thus fully described my invention in the manner required by the patent statutes, I wish it to be understood that my invention is not to be limited to the particular embodiments disclosed in the drawings and described in the specification, but rather only by the subjoined claims as interpreted in the light of the specification and drawings.

1 claim as my invention:

1. A heat exchanger in which a gaseous or vaporo-us fluid is brought into direct contact with a liquid, comprising: a casing; means including a porous baflie for introducing a gaseous or vaporous fluid into said casing; conduit means for conducting a pressurized liquid to the interior of said casing; a series of apertures formed in said conduit means in a side-by-side relationship for injecting said liquid into said fluid in said casing as a spaced series of substantially parallel jet streams; and means for forming said liquid jets into a plurality of spaced, noninterfering, flat, thin films of liquid, said last mentioned means comprising a plurality of parallel deflector plates, and leg means extending from said conduit means and connected to said deflector plates for supporting each deflector plate vertically in the path of one of said jet streams transversely to the jet streams and at a distance from the aperture forming that jet stream different at least from the distances between its adjacent deflector plates and their associated apertures, whereby the gaseous ar vaporous fluid has ready access to both sides of the plurality of substantially non-interfering flat liquid films.

2. A heat exchanger as set forth in claim 1 wherein two of said series of apertures are formed in said conduit means and are located on opposite sides of a vertical plane through the axis of said conduit means, each of said series being correspondingly associated with a corresponding plurality of said deflector plates, said leg means extending from said conduit and connected on opposite sides thereof with opposed deflector plates such that said deflector plates and said leg means comprise inverted U-shaped members with the leg means fastened to the upper portion of said conduit means and the deflector plates extend downwardly from the ends of the leg means on each side of said conduit means.

3. A heat exchanger as set forth in claim 1 wherein said conduit means comprises a main conduit extending into said casing and a plurality of branch conduits leading transversely from said main conduit, said series of apertures being formed in each of said branch conduits.

References Cited by the Examiner UNITED STATES PATENTS 963,354 7/1910 Braemer 239520,X 1,438,200 12/1922 Wallem. 1,867,878 7/1932 Coviello 239-520 1,868,632 7/1932 Edge. 2,389,005 11/1945 Sebald 261 2,452,716 11/1948 Bergquist 261-l 15 X 2,812,980 11/1957 Kadosch et al 239-522 X 3,158,666 11/ 1964 Heller et al 261-418 FOREIGN PATENTS 230,160 3/ 1925 Great Britain.

FRANK W. LUTTER, Primary Examiner.

R. WEAVER, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,301,538 January 31, 1967 William H. Gibson It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 11, strike out "including a porous baffle"; line 29, for "ar" read or Signed and sealed this 17th day of October 1967.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, J r.

Commissioner of Patents Attesting Officer

Claims (1)

1. A HEAT EXCHANGER IN WHICH A GASEOUS OR VAPOROUS FLUID IS BROUGHT INTO DIRECT CONTACT WITH A LIQUID, COMPRISING: A CASING; MEANS INCLUDING A POROUS BAFFLE FOR INTRODUCING A GASEOUS OR VAPOROUS FLUID INTO SAID CASING; CONDUIT MEANS FOR CONDUCTING A PRESSURIZED LIQUID TO THE INTERIOR OF SAID CASING; A SERIES OF APERTURES FORMED IN SAID CONDUIT MEANS IN A SIDE-BY-SIDE RELATIONSHIP FOR INJECTING SAID LIQUID INTO SAID FLUID IN SAID CASING AS A SPACED SERIES OF SUBSTANTIALLY PARALLEL JET STREAMS; AND MEANS FOR FORMING SAID LIQUID JETS INTO A PLURALITY OF SPACED, NONINTERFERING, FLAT, THIN FILMS OF LIQUID, SAID LAST MENTIONED MEANS COMPRISING A PLURALITY OF PARALLEL DEFLECTOR PLATES, AND LEG MEANS EXTENDING FROM SAID CONDUIT MEANS AND CONNECTED TO SAID DEFLECTOR PLATES FOR SUPPORTING EACH DEFLECTOR PLATE VERTICALLY IN THE PATH OF ONE OF SAID JET STREAMS TRANSVERSELY TO THE JET STREAMS AND AT A DISTANCE FROM THE APERTURE FORMING THAT JET STREAM DIFFERENT AT LEAST FROM THE DISTANCES BETWEEN ITS ADJACENT DEFLECTOR PLATES AND THEIR ASSOCIATED APERTURES, WHEREBY THE GASEOUS OR VAPOROUS FLUID HAS READY ACCESS TO BOTH SIDES OF THE PLURALITY OF SUBSTANTIALLY NON-INTERFERING FLAT LIQUID FILMS.

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