US3361196A

US3361196A - Flow vortex suppressor for inlet water box

Info

Publication number: US3361196A
Application number: US615442A
Authority: US
Inventors: Aoyama Hideyuki
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1966-02-14
Filing date: 1967-02-13
Publication date: 1968-01-02
Anticipated expiration: 1985-01-02
Also published as: JPS4425751Y1

Description

Jan. 2, 1968 -HlDEYUKl AOYAMA 3,361,196

FLOW VORTEX SUPPRESSOR FOR INLET WATER BOX- Filed Feb. 15, 1967 FIG.I

IO ll United States Patent 3,361,196 FLOW VORTEX SUPPRESSOR FOR INLET WATER BOX Hideyuki Aoyarna, Yokohama-shi, Japan, assignor to Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki-shi, Japan, a Japanese joint-stock company Filed Feb. 13, 1967, Ser. No. 615,442 Claims priority, application Japan, Feb. 14, 1966, 1/ 12,152 1 Claim. (Cl. 165-134) ABSTRACT OF THE DISCLOSURE Erosion of the entrance parts of water tubes at their inlet ends due to vortices in the inlet water box of a feed-water heater is prevented by a flow-regularizing device consisting, essentially, of a perforated outer cylinder with a closed end and an open end connected to the entrance opening of the feed-water inlet of the Water box, the incoming water being distributed and guided by one or more concentric flanged pipes within the outer cylinder to flow uniformly and steadily out of the outer cylinder, through the perforations, and into the water box, thereby to flow into the water tubes without formation of vortices.

This invention relates to feed-water heaters and more particularly to high-pressure feed-water heaters for use in installations such as thermal power plants. More specifically, the invention concerns a new and improved feed-water heater having a flow-regularizing (or flowrectifying) cylinder installed at the feed-water inlet of the front water box (or chamber) of a high-pressure feed water heater and operating to suppress development of vortices in the water box and thereby to prevent occurrence of inlet erosion sometimes referred to as (inlet attack).

In general, in a feed-water heater of the type referred above, the feed water supplied to the heater first enters a water box (or chamber) from which the water is caused to flow into heating tubes (water tubes). As described more fully hereinafter, the water entering the Water box tends to form violent vortices, which cause the above mentioned inlet erosion.

It is an object of the present invention to provide a feed-water heater having a flow-regularizing device of simple and inexpensive construction for effectively suppressingdevelopment of vortices in the water box of a feed-water heater thereby to prevent occurrence of inlet erosion at the inlet parts of the heating tubes (water tubes).

Another object of the invention is to provide a device of the above stated character which can be easily installed and left for automatic operation without attention. s

According to the present invention, briefly summarized, there is provided a feed-water heater having a flow-regularizing device designed to have a diffusing or dispersingaction On the water entering the water box of a feed water heater and comprising a perforated outer cylinder constituting a'cap over the entrance opening of the feedwater inlet and adistribution cylinder consisting of at least one flanged pipe each flanged pipe having a flange near one end thereof, the distribution cylinder being disposed within the outer cylinder and serving to distribute and guide the entering water evenly to the perforations in the outer cylinder, whereby the water flows uniformly and steadily out into the water box and hence into the water heating tubes of the heater.

The nature, principle, and details of the invention will be more clearly apparent from the following detailed 3,361,196 Patented Jan. 2, 1968 description when head in conjunction with the accompanying drawings, in which like parts are designated by like reference numerals.

In the drawings:

FIG. 1 is a partial side elevation view, in vertical section, showing the essential parts of a feed-water heater in which there is installed one example of a flow-regularizing cylinder constituting a preferred embodiment of the invention;

FIG. 2 is a sectional view taken along the horizontal plane indicated by line IIII in FIG. 1;

FIG. 3 is a similar horizontal sectional view corresponding to FIG. 2 and showing a second preferred embodiment of the invention;

FIG. 4 is a similar horizontal sectional view corresponding to FIGS. 2 and 3 and showing a third-preferred embodiment of the invention;

FIG. 5 is a perspective view, transparently represented, showing in outline distribution cylinders constituting essential elements of the flow-regularizing cylinder shown in FIGS. 1 through 4; and

FIG. 6 is a side elevation view, in vertical section, showing an example of a feed-water heater of general yp In general, a feed-water heater of the type to which the present invention is applicable comprises, essentially, as illustrated in FIG. 6, one or more heating tubes (water tubes) 1, a water box 2 constituting a passage for boiler feed water to. flow through the tubes 1, a shell 3 forming a passage for heating steam 'to flow outside of the tubes 1 and for drain water, a tube sheet 4 for supporting the heating tubes 1 with suitable spacing between these tubes 1 and the shell 3 and, at the same time, enabling the tubes to open comrnunicatively into the water box 2, a pipe base 6 forming a feed-water inlet 5, a feed-water outlet 7, and a partition 8.

In a heater of this character, in general, the inner are produced similarly as secondary wakes in a pipe bend. These vortices produce at the surface of the tube .sheet 4 a flow velocity component which is perpendicular to the axial direction of the heating tubes 1, and by which erosion is caused at parts such as: the inlet ends and the inlet inner surfaces of the heating tubes 1.

For preventing this attrition or inlet attack including erosion, an essential requirement is the suppression of the development of violent flow having a velocity component perpendicular to the axial direction of the heating tubes at the surface of the tube sheet 4 facing the interior of the water box 2.

The present invention contemplates the provision of means for fulfilling this requirement as described hereinbelow with respect to preferred embodiments of the invention.

In the first embodiment of the invention as illustrated in FIGS. 1 and 2, the flow-regularizing device has a distribution cylinder 12 made up of an assembly of concentrically arranged

flanged pipes

9, 10, and 11 respectively having progressively differing diameters and heights and having

flanges

15, 16, and 17, respectively, at their upper ends. The outer peripheries of the

flanges

15, 16, and 17, which are of equal diameter, are fixed to the inner surface of an outer cylinder 14 having a large number of small through holes 13, or perforations, in its vertical wall and having a closed upper end 18.

This fiow-regularizing device is placed in the inlet chamber 2a of the water box 2 of a feed-water heater and connected at its lower part to the feed-water inlet 5 of the water box, a cylindrical fitting member 14a integrally fixed to the lower end of the outer cylinder 14 being fitted into and secured to the upper end of the feedwater inlet 5. The lower ends of the

pipes

9, 10, and 11 lie in the same horizontal plane which is approximately coincident with the plane of the inner bottom surface of the inlet chamber 2a. While the distribution cylinder 12 in this example illustrated in FIGS. 1 and 2 is an assembly of a plurality of concentric flanged pipes, a single flanged pipe having a flange near one end thereof may also be used.

The outer cylinder 14 may be made of a perforated plate as in the example illustrated, or it may be made of a metal wire mesh. A specific ratio for optimum result is established between the total area of all holes 13 and the cross-sectional area of the opening of the feed-water inlet 5, the former being made larger than the latter.

In the first example illustrated in FIGS. 1 and 2, the outer cylinder 14 has a planar vertical wall part which is positioned to face parallelly the tube sheet 4 of the feed-water heater and is also provided with small holes 13. In the second example illustrated in FIG. 3, the above mentioned planar vertical wall of the outer cylinder 14a has no holes, while the third example illustrated in FIG. 4 has an outer cylinder 14b which is a fully circular cylinder without a planar vertical wall.

The flow-regularizing cylinder of the above described construction and installation according to the invention operates in the following manner. Feed water flowing as a jet into the inlet chamber 2a of the water box 2 is received by the annular spaces between the outer cylinder 14 and flanged

pipes

9, 10, and 11 and the interior of the pipe 11 and, after being deflected by the

flanges

15, 16, and 17 and the upper end 18 of the outer cylinder 14, is distributed into low-velocity currents which flow out through the small holes 13 into the inlet chamber 2a.

The feed water entering the interior of the outer cylinder 14 flows out therefrom at a flow rate which tends to increase toward the extreme end of the outer cylinder because of the effect of dynamic pressure, but by the use of a distribution cylinder 12 of suitable dimensions and dispositions of its flange pipes, it is possible to cause the water to flow out with substantially uniform flow rates, whereby the flow velocities of the water toward all heating tubes can be caused to be uniform.

The feed water which has entered through the feed- Water inlet 5 and flowed out through the small holes 13 in the above described manner assumes a steady regularized flow which is quite different from a strong jet flow having a high-velocity component perpendicular to the axial direction of the heating tubes 1. Accordingly, there is no occurrence of violent vortices at the surface of the tube sheet 4, whereby inlet erosion due to the feed water is effectively prevented.

In order to indicate more fully and in specific terms the effectiveness and utility of the flow-regularizing device of the feed-water heater of the invention, the following results of experiments carried out for the purpose of verifying this effectiveness and utility are presented.

As an experiment, comparative tests were carried out to determine the effects on the inlet ends of the feedwater heating tubes of the presence and absence of a flow-regularizing device according to the invention in a feed-water heater of a thermal power plant. The test Flow-regularizing Used N ct used device:

Operation time (hr.) 4,307

No abnormality...

Surface attrition in area from tube end to approximately 20 mm. inward.

Condition of inner surface of tube end.

Increase in inner diam- 0.3 mm., approx.

eter at tube end.

007 111111., approx" Thus, the present invention provides a device which is capable of eliminating jet flows and vortices, in the inlet chamber of the water box of a feed-water heater, arising from the configuration of the interior of the inlet chamber, and which is thereby capable of positively preventing inlet attack which would tend to occur at the heating tube inlet parts if the device were not used. Thus, the device of the invention contributes greatly to the durability of feed-water heaters. Moreover, the device has a simple and inexpensive construction and can be easily installed and left for automatic operation requiring no attention.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention as set forth in the appended claim.

What I claim is:

1. A feed-water heater comprising tubes for passing therethrough a first fluid, a shell enclosing the tubes and effective to cause the flow of a second fluid to accomplish heat exchange with the first fluid, a tube sheet for supporting at least one end of each tube, an enclosure structure forming a water box in cooperation with the tube sheet and having an opening for introducing the first fluid into the water box, a flow-regularizing cylinder installed within the enclosure structure and communicating with the opening, said flow-regularizing cylinder having numerous through holes in its peripheral wall and an imperforate top wall, and a distribution cylinder fitted into the interior of the flow-regularizing cylinder and coaxial therewith and having at the farthest end from the opening at least one flange in contact with the inner wall of the flow-regularizing cylinder.

References Cited UNITED STATES PATENTS 1,358,050 11/1920 Audianne 174 1,405,381 2/1922 Ackerman et a1 165174 1,662,236 3/1928 Coupland 165--174 2,099,186 11/1937 Anderegg 165174 X 2,602,647 7/1952 Miller 165-174 X ROBERT A. OLEARY, Primary Examiner.

A, W, DAVIS, JR., Assistant Examiner.