Note: Descriptions are shown in the official language in which they were submitted.
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il BACKGROUND OF THE INVENTION
1 ~
¦ This invention relates generally to a cartridge-type
filter for separating contaminants in a fluid, and more parti-
1 cularly to such a filter for separating solid contaminants in the
, circulating cooling water of a nuclear power plant.
,I Chemical attacks in nuclear power plants lead to the
formation of oxides or other substances on the surface of
various structural elements as, for example, on the inner sur-
i face of the reactor vessel, in conduits or on the surface of
1 components included in the reactor core. Further, flow and
abrasion result in the loosening of various machine elements,
such as valves, pumps, etc.
I Because the contaminants are formed and circulate in
' an environment with high radioactivity, radioactive isotopes are '
~` formed in the particulate material. For example, a radioactive
isotope Co 60 may be formed from an alloy such as cobalt. Thus,
the filter containing a considerable quantity of separated ~,
material is highly radioactive so that the handling of it involves
Ii special problems because of the radiation emitted by the filter
¦, material. The filter must thus be surrounded by radiation
- j~ protectors, and the removal and exchange of filter material must
take place via remote operation.
' SUMMARY OF THE INVENTION
!'
~ It is an object of the present invention to provide a
I filter wherein exchange and removal of the filter material may
be simply carried out in an effective and efficient manner
despite its high level of radiation.
The filter according to the invention is of a cartridge~
i filter-type in which a filter cartridge can be easily installed
or removed from a filter housing by simple remote control
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means. The filter housing has a top opening and a lid which
covers the opening, and the lid is capable of being connected
to one of several interconnected filter cartridges which contain '
I filter material for separating contaminants, primarily solid
jl particles, present in the cooling water of the reactor. The
cartridge filter may include a plurality of filter housings which
are suitably cylindrical and are vertically disposed. Each
filter housing has an inner, annular flange or shoulder defin-
1, ing a valve seat and serving to support the filter cartridges.
j One of the filter cartridges has an outer, annular seal ring in
~¦ sealing engagement with the shoulder for supporting the filter
cartridge within the housing and for dividing the housing into
two separate chambers respectively in communication with supply
Il and return conduits provided on the housing above and below the
seal ring. Foul water is supplied to the upper chamber and the
¦ filtered water is collected in the lower chamber and is returned
l! to the reactor vessel. The filter is suitably included in a
¦~ circuit parallel to the main water flow of the reactor with only ¦
Il a minor portion of the flow passing through this cleaning cir-
2 d Ijll cuit.
Several filter cartridges may be located in one filter
i housing and, the cartridges may be series- or parallel-
connected. Also, several filter housings may be included in one
,i filter group with the housings being either parallel-
1 or series-connected. The filter material contained within the
¦ filter cartridges may be located between strainers provided at
the inlet and outlet sides of each cartridge so that the foul
water will pass axially through the filter bed between the
I strainers. Or, each cartridge may have two concentric, annular
gap strainers between which an annular filter bed is located,
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through which the foul water ~lows radially.. The ~ilter bed
material, used in either of these constructi.o~s, ma~ be com-
prised of metal wire clippings. A filter ca~tridge within the
housing may be joined to the lid co~e~i~g the top opening such
that when the lid is removed, the cartridge or cartridges are
lifted together therewi.th. And, to increase the sealing en.gage-
ment between the seal ring and the shoulder in the filter housing,
springs may be provided between the lid and the filter cartridge.
Accord.in~ly, the in.~ention claimed therein is
10 essentially a cartridge filter for separatin.g radioactive con-
taminants from reactor cooling water used, for example, in
nuclear power plants, comprising, a.t leas.t one top opening filter
housing having a supply conduit thereon for admittin.g cooling
water to be filtered and a return conduit th.ereon for
returning the filtered water, a lid covering said top opening,
said housing having in its upper part an ïnwardly directed
annular shoulder defining a ~alve.seat, at least one removable
filter cartridge containing filter materi.al and being pro~ided
at its upper part with an outwardly directed supporting ring
thereon in sealing en.gagement with said shoulder for carrying
said filter cartridge freely suspended within said housing,
said cartridge diYiding said housin.g into two separate chambers
respectively in communication with said supply and said return
conduits, and means interconnecting said lid and said filter
cartridge so that by lifting said lid the cartridge is simulta-
neously lifted.
Other objects, ad~antages and novel features of the
invention will become more apparent from the followlng detalled
description of preferred embodiments of the invention when taken
in conjunction with the accompanying drawlngs.
BRIEF DESCRIPTION OF T~E DRAWINGS
Figure 1 is a vertical sectional view of the filter
1~l3 7~ 9
according to the invention as positioned in a nuclear power
plant,
Figure 2 is a.view simila:rl to Figure 1 showing the
manner of removing the filter cartridges~
Figures 3 and 4 are ~ertica~ sectional~iews of the
Figure 1 filter, at enlarged scale, of two embodiments.acco~ding
. to the invention~
Figure 5 is a detail view in.~ertical section a.t an
even larger scale of a portion of the Figure 3 embodiment;~ and
Figure 6 is a horizontal sectian.al ~ie~ taken through
the concentric, annular gap strainers of Figure 5.
DETAILED DESCRIPTION OF THE IN~ENTION
A portion of a nuclear power plant needed to describe
the invention is shown in Figure 1 as including a space 1
defined by concrete ~alls 2 and a closing lid 3 which includes
an outer annular section.3a and an inner~ plug 3b. A cartridge
_ . . . _ . . . _ . _ _ . , _
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filter unit according to the invention, generally designated 4,
is located in space 1 and comprises a cylindrical filter housing
5 having a top opening covered by a detachable lid 6 attached to
the housing by bolts 9. The filter housing is connected to the
primary cooling water system of a reactor (not shown) by a supply
conduit 7 for receiving the foul water to be cleaned and by a
return conduit 8 for returning the cleaned water. Since filter
unit 4 communicates with the primary cooling system of the reac-
I tor, the filter unit must be constructed to withstand the same
pressure existing in the system, i.e., usually about 70 bar in a
boiling reactor. It may also be suitable to adapt the filter
' unit to the steam pressure system, which is about 300C. Two
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filter cartridges 10 and 11 are mounted in the filter housing,
upper cartridge 10 being connected to an inlet portion 12 for
~ control of the direction of the water flow at the inlet end of
this cartridge. The cartridges are interconnected, as in a manner
to be later described, and inlet portion 12 interconnects lid 6
with cartridge 10 so that cartridges 10 and 11 may be removed
upon the removal of lid 6 as shown in Figure 2. During such
~ 20 ,I removal operation, concrete plug 3_ is removed and a radiation
protection device 13 is mounted on lid 3a over opening 14
defined by the removal of the plug. A rod 15 is connected to
! lid 6 and the entire unit comprising lid 6, inlet portion 12 and
cartridges 10,11 are lifted up into device 13 by means of a
~ suitable hoisting device. Radiation protection device 13
together with its contents is then removed, cartridges 10 and 11
and inlet portion 12 are separated, whereafter cartridges 10 and
11 may be cast into concrete or deposited in any conventional
manner.
As shown in Figures 3, 4, and 5, the upper portion of
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filter housing 5 has a larger diameter than its lower portion.
An annular shoulder 16 is formed at the transition between the
larger and smaller diameters, such shoulder or flange having a
Il conical surface 17 defining a valve seat. Upper cartridge 10
¦I has a seal ring 20 thereon of substantially spherical shape as
at 21 for sealingly engaging with surface 17 to thereby divide
the filter housing into two separate upper and lower chambers
22 and 23 which are sealed against intercommunication. The
Il upper and lower chambers respectively communicate with the supply
1~ and return conduits 7 and 8.
¦l Thus, interconnected cartridges 10 and 11 are suspended
from ring 20 in engagement with shoulder 16. Upper cartridge 10
includes a sleeve 24 spaced inwardly from the inner surface of
ll the filter housing and having radially extending flanges 25 and
¦ 26 at opposite ends. Lower cartridge 11 includes a similar
sleeve 27 slightly spaced inwardly from the inner surface of the ¦
~ filter housing and having a radially extending flange 25a at
¦~ its upper end and an annular bottom wall 28. Inlet portion 12
¦1 is provided with flanges 30 and 31 at its opposite ends, and
li cartridges 10 and 11 are interconnected by bolts 32. Inlet
portion 12 and cartridge 10 are interconnected by bolts 33, and
,~ the inlet portion is connected to lid 6 by bolts 34 extending
jl through flange 31 and into the lid. Bolts 32 and 33 may be
,~ welded to flanges 25 and 25a, and flanges 26 and 30 may be pro-
I vided with openings for the bolt heads and slots for the bolt
! shanks so that the bolt heads may be inserted through the open-
ings whereafter the cartridges are turned so that the bolt
, shanks are moved into the slots to thereby form a bayonet-type
l! connection.
,; Coil springs 29 are located between lid 6 and plate 31
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for resiliently biasing the entire cartridge unit with an
increased force against surface 17 to thereby increase the seal
between surfaces 21 and 17. Filter material 35, which may be in
~i the form of metal wire chips or trimmings, lies between two
¦~ annular concentric strainers 36 and 37 and between closing plate
¦ 38 at the upper end of cartridge 10 and lower ring 40 of this
cartridge. Similar filter material is located between two annu-
~ lar concentric strainers 36 and 37 and between upper and lower
¦ rings 41 and 28 of lower cartridge 11.
¦ As shown in Figures 5 and 6, strainers 36 and 37
1~ respectively include rings 42 and 43 separated by spacers 44
¦l and 45 and held in stacked relationship, respectively, by bolts
¦ 46. The thickness of the gaps between the stacked rings is
Il designed to be somewhat smalIer than the grain size of filter
¦ material 35. Thus, if metal wire clippings having a length of
¦! 0.4 mm and a diamter of 0.4 mm are used, spaces 44 and 45 would
¦i have a thickness of 0.2 mm.
In accordance with the filter design shown in Figure
Il 3, foul water to be cleaned flows from supply conduit 7 and into
I! chamber 22 and from there to the interior of inlet portion 12 via
¦~ the small inlet openings shown in the drawings. The foul water
¦ then flows into space 47 and down into intercommunicating annular
¦ gaps 48 and 50 (Fig. 5) which are formed between annular
I strainers 36 and the inner surfaces of sleeves 24 and 27. The
1l water in gaps 48 and 50 flow radially through filter material 35
of both cartridges and into a central space 51 defined within
j inner annular strainers 37, then down into the bottom of lower
chamber 23 and out through returr. conduit 8.
I, In the filter design according to Figure 4, which is
similar in many respects to Figure 3, cartridges 10 and 11
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respectively have lids 51,52 and bottom walls 53,54 having open-
ings therein over which strainers 55,56 and 57,58 are respective-
, ly mounted. The cartridges contain filter material 60 in the
I spaces between the strainers. Lid 51 and bottom plate 53 are
interconnected by a sleeve 61 spaced slightly inwardly of sleeve
24 so as to form an annular gap 62 therewith. Lid 52 and bottom
wall 54 are interconnected by sleeve 27 and by an inner sleeve
or tube 63 thus defining with sleeve 27 an annular space for
~'l filter material 60. Sleeve 63 defines a central axial channel
64, and another bottom wall 65 on sleeve 61 of cartridge 10 is
provided with a depending sleeve 66 which fits within a muff
67 extending upwardly from sleeve 63 for interconnecting car-
tridges 10 and 11 together. Space 68 between bottom walls 53
1 and 65 is therefore in open communication with channel 64.
l~ The foul water to-be cleaned flows into chamber 22
' via supply conduit 7 and from there flows into space 47 via
inlet portion 12, all as in the same manner described with
reference to Figure 3. The foul water then flows along one
~, path from space 47 through strainer 55 and axially through the
l bed of filter material 60 in cartridge 10 and then through
~ , strainer 56 and into space 68 and from there through channel 64
, to chamber 23 and out through return conduit 8. Also, the foul
water flows along another path from space 47 through annular
' gap 62 and into an annular space 69 located outwardly of muff
67 and from there it flows through strainer 57 and axially
, through the bed of filter material 60 in cartridge 11 and then
through strainer 58 and into lower chamber 23 and out through
return conduit 8.
I It should be pointed out that sleeves 24 and 27 of the
cartridges 10 and 11 are interconnected at the bottom and top
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thereof, respectively, in the same manner as that described
with reference to Figure 3, i.e., via bayonet-type connections.
Also, the bottom of inlet portion 12 is interconnected with the
~ top of sleeve 24 by means of the same bayonet-type connections
described for Figure 3, and the top of inlet portion 12 has a
plate 31 thereon mounted to lid 6 by bolts 34 with coil springs
29 between plate 31 and the lid for resiliently urging the seal
ring on cartridge 10 against shoulder 16 when the lid is mounted
1 over the top opening of the filter housing, all as similarly
~ described with reference to Figure 3.
Obviously, many modifications and variations of the
present invention are made possible in the light of the above
teachings. For example, filter cartridges of different shapes
I containing different filter materials may be utilized as compared
¦ to that disclosed herein without departing from the invention.
For example, the filter cartridges may be constructed as plane
filters of different types. And, seal ring 20 may alternately
be provided on inlet portion 12 at a suitable location for
' sealingly engaging with surface 17 so as to divide the filter
_ 20 1 housing into the two separate upper and lower chambers. It is
1, .
, therefore to be understood that within the scope of the appended
,I claims the invention may be practiced otherwise than as
specifically described.
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