CA1169364A

CA1169364A - Steam processing apparatus

Info

Publication number: CA1169364A
Application number: CA000395677A
Authority: CA
Inventors: Albert J. Zipay; William D. Stevens; Walter P. Gorzegno
Original assignee: Foster Wheeler Energy Corp
Current assignee: Foster Wheeler Energy Corp
Priority date: 1981-03-27
Filing date: 1982-02-05
Publication date: 1984-06-19
Also published as: JPS57184411A; ES510298A0; GB2096026B; AU7983082A; AU547812B2; JPS60181512U; ES8308030A1; GB2096026A

Abstract

STEAM PROCESSING APPARATUS

ABSTRACT OF THE DISCLOSURE

A steam processing apparatus in which a plurality of separators are disposed along the length of a cylindrical drum having inlet means for receiving a mixture of liquid and vapor and outlet means for discharging the separated liquid and vapor. Each separator includes an arcuate arm for discharging the mixture against a baffle after which the separated liquid is passed to the drum liquid outlet and the separated vapor is passed upwardly by natural buoyant forces to the drum vapor outlet. The separators are disposed in a plurality of rows - two to each side of the axis of the drum along the length thereof.

Description

STEAM PROCESSING APPARATUS

BACKGROUND OE' THE INVENTION
This invention relates to a steam processing apparatus and, more particularly, to an apparatus for receiving a mixture of liquid and vapor, separating the vapor from the liquid and discharging the vapor and the liguid from sepaxate outlets.
In natural circulation vapor generators, mixtures of water and steam rise in heated steam-generating tubes and discharge into one or more large steam drums disposed in an elevated position above the tubes. The dxums include means to separate the water from the steam wi~h the latter being removed through openings of the upper portions of the drum and the former being recirculated through downcomers to the boiler and back to the steam generating tubes to complete the natural circulation loop. - .
In relatively large installations employing natural circulation vapor generators, it is essential that an efficient separation of the steam from the water be effected in the drum with minimal pressure loss in order to ~urnish steam of the required purit~ to the point o~ use, and steam- ¦
free water to thecirculation system. ~n these arran~ements, the expansion of the water-steam mixture through the separator results in a substantial pressure ~rop which, if too large, can adversely effect the circulation system. Also at low pressure the steam specific volume is high and a separator must have sufficient flow area to minimize pressure loss and still achieve separation.
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Many of the prior art arrang~ments designed to minimize the pressure drop and maximize the flow area have included a drum with an extraordinarily large length which is incompatible from a fabrication standpoint with the furnace width dimension for a given capacity unit. As a result, the drum often overhangs relative to the furnace which tends to increase material and erection costs.

SUMMARY OF THE INVENTION

Accordingly the present invention seeks to provide a steam processing apparatus in which liquid is separa-ted from vapor at a relatively low pressure loss and an apparatus of the above type which is of a simple, efficient and inexpensive design.

Further the present invention seeks to provide an apparatus of the above type in which a drum is provided, the length of which is relatively short for a given capacity unit and, therefore, can be fabricated in a relatively inexpensive manner.

The invention pertains to a steam processing apparatus which comprises a cylindrical drum having inlet means ~or receiving a mixture of liquid and vapor from an external source with first outlet means for discharging the liquid and second outlet means for discharging the vapor. A plurality of rows of separators are disposed along the length of the drum to either side of the axis of the drum, with a portion of each separator of a particular row extending partially into the space between adjacent separators of the adjacent row. Each separator comprises a riser pipe communicating with the inlet means for receiving the mixture. A shell means is disposed in a spaced -93~
relation to the riser pipe, and a plurality of discharge slots are formed through the riser pipe in an angularly spaced relation. An arcuate shaped discharge member registers with each slot for receiving the mixture and discharging it against the shell means to facilitate the separation of the liquid from the vapor, the liquid collecting on the shell means and falling to the first outlet means by gravitational forces, with the vapor rising to the second outlet means by buoyant forces.

BRIEF DESCRIPTION OF THE DRAWINGS

The above brief description, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed - description of the presently preferred but nonetheless illustrative embodiment in accordance with the present invention when taken in conjunction with the accompanying drawings in which:
Fig. 1 is a vertical cross-sectional view of the steam processing apparatus of the present invention;
Fig. 2 i5 a cross-sectional view taken along the line 2 - 2 of Fig. l;
Fig. 3 is a cross-sectional view taken along line 3 - 3 of Fig. 2; and Fig. 4 lS a cross-sectional view taken along line 4 - 4 of Fig. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring specifically to Fig. 1 of the drawing, the reference numeral 10 refers in general to the steam processing apparatus of the present invention which includes a ~t33~

steam drum 12 which for~.s a portion of a natural circulation steam-water system. The drum 12 is of an elongated cylinArical shape and is disposed with its axis parallel to the hori~ontal.
The upper end por~ions of two groups of steam generating risers or tubes 14 extend through the drum 12 and communicate with the interior of the drum to introduce a mixture of water and steam into the drum. A plurality of downcomers (one of which is shown by the reference numeral 16) extend from the lower portion of the drum to discharge the separated water (along with a quantity of feed water) t~ a furnace tnot shown) where the water is heated and recycled bac~
through the drum 12. Dried steam is removed from the drum 12 through a plurality o discharge tubes 17 disposed at the upper portion of the drum.

An elongated girth baffle 18 is provided within the drum immediately above the end portions of the tubes 14 to define a chamber 20 for receiving the mixture of water and steam from the tubes 14. A plurality of separators 22 are disposed in the drum 12 and are arranged in ~our hori~
zontally extendings rows, two extending to either side of the axis of the drum. Each separator 22 includes a riser pipe 24, the lower end portion of which is bolted to the girth baffle 18. The riser pipes 24 are adapted to receive the water- :
steam mixture from their respective chambers 20 and separate the mixture into steam and water as will be des-cribed in detail later. Although not clear from the dra~ings, it is noted that the chamber 20 takes the form of a concentric annulus inside the drum 12 that permits flow from one side of the drum to the other. This annulus is ; ~0 interrupted only by the openings in the drum 12 for the _~ _ 3~

downcomers 16 and by the support structure shown. Therefore, water can flow through an open girth area in between the latter openings and ~upport structure.
Two hori~ontally extending eed pipes 26 are disposed in the chamber 20 and are adapted to introduce water into the drum 12 which flows through the separators 22 with the mixture of water and steam to replenish the supply of steam that is discharged from the separators and, thus, ~aintain a constant water level, shown by the reference letter L.
This water passes downwardly through a vortex eliminator 28 to the downcomer 16 for discharge back into the natural circulation loop. The vortex eliminator 28 operates in a conventional manner to prevent swirling of the water as it discharges from the drum 12 into the downcomer 16, and thus reduces the entrance loss to the downcomer 16. In addition, the vortex eliminator 28 also prevents the steam from being drawn fro~ the upper portion of the drum into the downcomer.
Since the vortex eliminator 28 is of a conventional design~
it will not be described in any further detail.
A plurality of steam dryers are disposed in the upper portion of the drum 12 with one being shown by the reference numeral 30 in ~ig. 1. The dryers 30 are supported by a conventional support structure in a position immediately 7 above the separators 22 and immediateIy below a dry box 32, .
also of a conventional design. The dryers 30 include a plurality of plates ~not shown) which are in a nested, but spaced, relationship and may be of the cbevron type disclosed " in U. S. Patent No. 2,472,101, issued on June 7, 1949. The dryers 30 function to dry the steam dischar~ing from the 33~

upper portion of the separators 22 and separate any entrained water particles carried over with the steam as it flows through the space between the nested plates and through the dry box for discharge from the tubes 17.
As shown in Fig. 2, which depicts the two adjacent rows of separators 22 disposed on one side of the axis of the drum 12, the separators in each row are spaced slightly apart in a horizontal direction with a portion o each separator of a particular row extending partially into the space between adjacent separators o~ the adjacent row. Of course, this mLnimizes the space taken up by the separators

2~ and contributes to the advantages set forth herein.
Referring specifically to Figs. 3 and 4 which depict the details of a separator ~, the reference numeral 36 refers to an upright cylindrical shell through which the riser pipe 24 extends in coaxial relationship. The riser pipe 24 has a flanged end portion 24a which is bolted to the girth baffle 18 ~Fig. 1) and receives a mixture of a water and steam from the tubes 14.
A cap 33 extends over the upper end of the pipe 24 and a plurality of slots 40 (Fig. 4) are formed through the upper wall portion of the pipe 24. A plurality o~ sub-stantially spiral shaped~arms 42 are connected to the pipe 24 in registry with ~he slots 40 with the free ends of the arms being open to permit the water-steam mixture to dischar~e therefrom in a substantially tangential direction relative to the shell 36.
A support structure is provided within the shell 36 for supporting the riser pipe 24 within the shell in the coaxial posi~ion shown. As a non-limitive example, the support .

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structure can include a pluxality of upper support struts 46 and/or a plurality of lower support struts 48.
A wire mesh unit 50 is disposed at the upper erld portion of the shell 36 for filtering any entrained water particles from ~he steam exiting from the separator and is retained by a cross assembly 52 ~Fig. 2). The unit 50 is supported in the position shown by a bolt assembly 54 extending in threaded engagement with the cap 38 of the riser pipe 24.
As a result of the above, the mixture of water and steam entering the end portion 24a of the riser pipe 24 rises upwardly in the riser pipe and then passes radially outwardly from the pipe through the slots 40 and into the arms 42 where it is directed tangentially against the inner wall of the shell 36. This creates a vortex, or swirling,strea~ of : fluid with the resulting centrifugal forces causing the vapor portion of the mixture to travel away from the inner wall of the shell 36 and towards the center of the swirling stream and pass upwardly, by virtue of its buoyance, into the upper portion of the shell 36 and through the wire mesh unit 50. The water portion of the mixture collects on, -~
and flows down, the inner wall of the shell 36 until it falls into the reservoir of water disposed above the girth baffle 18 ~Fig. 1), before passing through the ~ortex eliminator 28 and into the downcomer 16 for recirculation.
Referring again to Fig. 1, the steam from the separators 22 passes upwardly through the chevron driers 30 into the dry bo~ 32 whereby the steam is dried and separated from any entrained water particles before passing outwardly from the drum 12 through the discharge tubes 17 as shown by the ,0 dashed flow arrows in Figs. 1 and 3.

In view o~ the foregoing, an efficient and compact steam processing apparatus is provided which enables the drum length to be decreased relative to the furnace width dimension for a given capacity unit, and thus permits an increase in loadiny per foot of drum length. In addition, the decreased drum length reduces material and erection costs for the drum, and the number o~ riser circuits to, and drum steam discharge tubes from, the drum. ~

A latitude of modification, change and substitution is !O intended in the foregoing disclosure and in some instances some featuxes of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention therein.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A steam processing apparatus comprising a cylindrical drum having inlet means for receiving a mixture of liquid and vapor from an external source; first outlet means for discharging said liquid and second outlet means for discharging said vapor; and a plurality of rows of separators disposed along the length of said drum to either side of the axis of said drum with a portion of each separator of a particular row extending partially into the space between adjacent separators of the adjacent row; each separator comprising a riser pipe communicating with said inlet means for receiving said mixture; shell means disposed in a spaced relation to said riser pipe, a plurality of discharge slots formed through said riser pipe in an angularly spaced relation, and an arcuate shaped discharge member registering with each slot for receiving said mixture and discharging it against said shell means to facilitate the separation of said liquid from said vapor, said liquid collecting on said shell means and falling to said first outlet means by gravitational forces and said vapor rising to said second outlet means by buoyant forces.

2. The apparatus of Claim 1 wherein said drum is oriented in a horizontal direction and wherein said separators are disposed along the length of said drum with their respective riser pipes extending in a vertical direction.

3. The apparatus of Claims 1 and 2 further comprising means disposed between said separators and said second outlet means for drying said vapor.