Note: Descriptions are shown in the official language in which they were submitted.
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
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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
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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
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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
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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.
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