Note: Descriptions are shown in the official language in which they were submitted.
FILTERING IN TOl~R FILTER WITH REV~ltS~D
W.~TER JET ~ILTER REGENERATION
The invention relates to a proces~ and equip-
ment ~or filterlng li~uid~, especially water flowin~
horizontally through a sand ~ilter grain column placed
ir~ tower filter, where the re~eneration9 cleaning
of thc various contam~hated ~ilter parts i~ oarried
out exclusively with injection of liquid j~t~o
~ iltering of the liquids has become a ~requent
practice during the recent decades in various fields
of the industry, and this process has gained vital
importance due to the increasing water ~hortage
oonsequent upon the rapidly increasing water con-
s~mptionO As a result, ths tower ~ilters stepped
lnto thc foreground repre~e~nting g:reat progres~
in thè ~iltering o~ liquid~l9 carryin~ o~t the
~iltering with the liquid f`lowing horizontaily
through the vertlcal ~ilter tower9 and which
in contrast with the earlier horizon$al filtering
meth~ds ~nd equipment - ha~e realized the more
economical cleaning o~ the untrea~ed waters~as
well a~ reduction of ~h~ investment-; and operatin~
costs and 1mprovement o~ the space uti~ization~
Such progre~3 and equipment are describcd
in the Hungarian patent NoO 154 412~ ~urther
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progress was attained by the invention described
in the Hungarian patent No.-163 094~ representin~
mainly the improvement achieved in the quality of
filtering cornpared to the filtering quality
produced by the earlier tower filter~.
Th~ experi~nces acquired ln the cour~e of
filter tower op~rations brought up certain dif~i~
cultie~ a~d di~dvantages, on th~ basis of which
it ~ecAm~ po~sible to determine the direction of
further deYelopment~ The diffi~ultie~ turned up
fir~t of all in ¢onhection with the applied
method, according to whi¢h regeneration of the
contaminated filter column was carr~ed out'at
every type o~ the filter towers. by recirculat~on
or baokwashing a~ter long-~ or short term operation
in such a way~ that thc contaminated filter
grain~ were carried from the cone-shaped collecting
spaGe at tha bottom of th~ filter tower into
the collecting sp~ce on the top of the filter
thro.ugh pipes made for thi3 purpose, pl~ced out
~ide or ~id~ ~he ~ilter tower by use o~ a
con~enient method ~ compress~d air flow, inJec~or9
mammoth-pumpjg then after washing and ettling
they wer~ carr~od or washed back into the upper
part o~ th~ fLlter ool~mn. ~he~e traditional
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methods of regenera-tion are unfavourable in se-
veral reE~pccts, such a~:
dead space~ remaining în the proce~s of
backwashing, deteriorating the quality of ~ilter-
~ng due to slump of the sand,
- pipe ~ystem and machinery of ~he~ recir-
culation incu.r additional cost in the course
of investment and maintenance~ -
~ owing to clogglng of the narrow cros~
sections of the slurry pipe, the pre~ent method
of reciroulation results in conslderable loss
of operating timo and 10~5 of oapac~ty,
- reco~ery o~ the f`ilter grains from the
cone-shaped collecting tank during regeneration
restricts the conical ~ormation of the tower ~ilter,
~or it requires ~l~nifioant inactive height~
the conical bottom is especially unfavourable
in th~ high~capacity filter un~t~, since~it fur~
ther reduces the proportion of u~e~ul ~olumet the
co~t o~tooling and for statical reasons the
speolfi¢ materlal utillzation too ~Ivill be in-
oreasillgO
CIeaning the periodioally clogged up sieve
surfac~, ~orming the wall of the filtered:water
ooLleoting ~pac~ causes simila~ly great difficulty
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in the known tower filters, because the large surY
face reduces the ~peed~ con~equently thetcleaning
wi-th back flushihg can not be carried out effectively
and in acceptable qualityO
~ inally it i~ di~ficult to remove the sand from
the untreated water-distributing space developed
di~ferently ~t the various types o~ tower filter,
into which the contaminated sand pa.~se~ mainly
during regeneration.o~ the filter grain column.
The invention is aimed at eliminating the
existing disadvantage~ occurring at regeneration of
the tower ~ilter~, and to attain a more ef~ective,
better~ cheaper and more.productive solution ~or
; the regeneration and cleaning of the contaminated
¦ ~iltcr grain column and ot.her filter part~9 further~
more at increasing the eoo.nomic ef~iciency through
le~s space requirement and ~elo~ lec~ raw materials~
The invention i5 based on the recognition,
that above goal ~8 atta~nable, thus the disadvan
tages connected with co~tlines~ of the equipment,
quality o~ the ~ilterlng and time o~ the regenera-
tion ari~ing~mainly at regeneration o~ the tower
:~ilter~ can be completely eliminated, provided that
regeneration Or the ~lter is aarried out exclusively
with injectio~ of water .jets of proper position,
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direction and ~peed, be~ides the necesnary7 suii;ahl~
~tructllral de~ign~ . :
Thus the invention i8 a proces~ ~or filtering
liquid~ flowing horizontally through the ~lt~r
column, charact~rized i~ that the regeneration of . .
the contaminated filter column i~ carried out
without flny extra ~qulpment Jmammoth-pump, comp-
re~sor, or watex jet pump/ only by in~ection of
water jets in such a way~ that the ~ilte:r col~n
is ~lurried at the bottom, brin~ing about reversed
flow wlth pres~ure of the water ~ets, thus bringing
about recirculation and backwa~hing, whe.reby ~he
filt~r grain~ are cleaned. Since slurrying the .
bottom of the filter col~n can be e~tended -to
a ~maller or larger area ~y ~arying the intensity
o~ the in~ected water ~et~, hence the ratio betweon
the recircuLation and baokwashin~ can be varied
at w~ in the sand columnO ~ackwashing of t~e
: ~iltered water co]lecting pipe and remoYal of the ~ -
`~and ~rom the untreated wate~di~tributing gap
: with water jet represent essential parts of the
in~ention, the latter operations being applicabl~
independently too in the earlier sand ~ilter~ or
these filters~can be con~erted sub~equen~ly as well~
: ~ The invention relate~ al~o to an èquipment
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to carry out the proce~, in which according to the
directlon of the ~low a narrow gap ~ brought about
before the filter grain column with wall of non
overlapp~ng panels, communicating through a large
gap underneath with the ~ilter grain column. This
gap serves for distribution Qf the water to be
fiLtered and ~or the path o~ the filter grain re-
circul~tion during rege~eration of the filter co
l~mnO ~urthermore a lower space is developed with
deflectirlg plate in the equipment under the Dn-
treated water distrlbuting gap, in order that àfter
cleanlng o~ the filter grain column, one or seve~
ral water jet~ are in~eoted for removal of the
sand ~rom the distributing gap, when by breaking
up on impact flnd ~cattering the jets come into a
sw1rling motion, then ~lowing upwards carry the
~ilter grain~ getting here during the recircula-
tion onto the top of the filter column~ th~reby
~reeing the untreated water di~tributing gap.
Finally ~ollowing the flo~q o~ liquid9 a vertical
~`collecting pipe ~ not letting through the ~and
` gra1ns, but~letting throwgh the ~ilter~ed water
: ~ i3 plaoed into the equipme~t to the wall o~ the
~ilter tank behind the filter column~ for dis-
charging the filtered water ~rom the tankO
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Tlle up~er ~nd o~ the collecting pipe i.s provid~!d
with a speed accelerating thro~t connected lwith
the filtered water-return pipeO ~ .
q'he experiences acquired with the traditional
tower filters have shown9 that even the many time~
over~ized clean water-discha~gi~gp: surface6 can
not prevent either the clo~ging of the sieve sur
f~cc sooner or laterO Such clog~ing may be caused
for in~tance by the tiny grains always existing
in the ~ilter sand, wedged up in the sieve holes;
the colloidal impuriti`es passing through the ~and
layer get deposi;ted o~ the ~ieve sur~ace~ during
temporary failure in the chemicals' supply; scale
precipitatLng on the ~ieve, due to pressure drop
in case of filtering deep waters. Such clo~ed
up large ~urfaces can not be e~ectively cleaned
with back ~lu~hing, becaule of the low velocity.
The solution according to the invention
start~ out ~rom oonceptual considerations contrary
to the establlshed practiceO Namely ~rom the i~ea .
that it uses such small surface onl~ ~or collection
,
o~ the ~iltered water, which ju~t let~ through
.the approprlate quantity of filtered water. Such
,
relativel~small surface can be back ~lu~hed e~fec-
ti~ely, beoause the backflushing water f~ows lvith
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~u:Eficicn-t velocity fxom the YieVe SUrfaCQ to
wasll out the weclged up sand g.rains and adherin~
impuritiesO I-Iowever, for this purpose it W.lS
neces3ary to ensure that th.e backwashing water
sho~ld flow with adequate velocity both on the
lower and upper end of the ~ieve surface~ '~he
experiments demon~trate tha-t it i~ prac-ticable to
,! u~e a ~ingle vertical colleoting pipe for collec
tion of the filtered water, into which th.e ~lush-
ing water is conducted from the top downward~
through the speed accelerating throat at the rate
of 5-15 m/scc.
The experiment~ prove~ that in such case
the flushing water does 110t esc~pe throug,h the
upper part of the sieve pipe, because the injected
water Jet penetrates to the bottom o~ the sieve
pipe, there impacting a.nd con~es~ing ensures a
practically uniform flow-out on the whole surface~
In accordance wlth abo~e9 the regeneration
is started at the end of each filtering period7
by letting filtered water into the collecting pipe
of the clean water from the top downwards at the
already mentioned rate of 5-15 m/~ec for a few ~e-
conds. Since according to above, only a single
collecting pipe is u~ed, the flu~hing water ~lows
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at a high speed on its relatively small ~urfaceinto the filter column,.and thus it cleans not only
the jacket of the collecting pipe, but it washes
out completely the thin sand layer in its full
lengtk between the collecting pipe and filter tank~
This way formatlon of the slump~ng sand layer be-
hind the collecting pipe becomes impossibleO
'~h~ 8 i~ ~ollowed with regeneration of the
filter columnO ~his i~ carrled out by underwa~hing
the filter grain column with water jets, and the
~lurry flowing in the opposite direction - making
it to flow upwards in the untreated wat~r di tribut
ing gap, that i~ oonnected with the sand oolumn at
the bottom - i8 carried ~ to the top of the fil-
ter grain column~ sattled, and meanwhile the waste
watel~ is discharged through the ove.rflowO
~ y the time the ~ilter grain column,is cleaned9
the recircula-ting and backwashing water jets are
turned off and conducted into the lower p~art of the
untreated water-distributing gap in such ja way,
`that the suitably distributed sand-removing water
jet~ slurry the sand only in the untreated water
dl~tr~buting gap a~d ~ash it up onto the top of the
sand column,- wLthout underwashing the filter columnO
Velocity of the liquid to ba filtered -
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conducted horizontally through the sand column in the
filtering process of the invention - and the sand grain
size are selected in such a way, that penetration of the
filtered contaminating particles should extend only to
about half of the filter column, while the other half of
the column should serve as a protective layer to ensure
the cleanliness of the filtered water.
Thus in one of the preferable construction
alternatives of the equipment according to the invention,
the filter column is divided vertically with a perforated
plate containing large holes, and this way the sand layer
in the front and rear on both sides of the perforated plate
- can be regenerated separately from each other - the layer
in the rear with less frequency - by slurrying, recircula-
tion and backwashing, because the sand grains do not mix
with each other in the practice, even if the holes are much
bigger than the sand grains.
Since practically only the Eront layer of the
filter column divided with the perEorated plate gets clogged
up during filtering, there~ore onl~ this has to be recircu-
lated during each regeneration, while the rear layer - which
hardly gets contaminated - should be cleaned occasionally only.
Thus by dividing the filter column into two layers with the
perforated plate, the time of regeneration can be reduced to
half in the practice.
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~-t another preferable construction alternative
of the invention, two sand columns axe placed in the filter
tank symmetrically with the untreated water-distributing
gap of common diametral plane, when the two filter columns
are provided with separate collecting pipes.
The invention is described in detail with the use
of drawings, in which Figure 1 shows the structure and fun-
ction of the angular tower filter in vertical section,
Figure 2 is the tower filter shown in Fig. 1~, -
in horizontal section,
Figure 3 shows a tower filter developed with two
filter grain columns, placed on both sides of a common dis- -
tributing gap,
Figure 4 is the vertical section of the tower fil-
ter of Fig. 3.
At a version of the tower filter of the invention
shown in Fig. 1. and 2., the untreated water or filterable
water distributing gap 2 is situated behind the front wall 1
` of the tank, surrounded by the louv,ered panel wall 4 on the
side facing.the
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sand col1lmn 30 q'he water to be filtered i~ conducted
.into the di~tributing gap ? through the inlet pipe 5t
~rom which -the water can flow upwardsO ~he ~and
column opposite the front wall 1 is ~urro~nded by
the rear wall 6 oE the tank, in the vicinity of
which the collecting pipe 7 of the filtered water
i~ placed in the middleg connected with the outlet
pipe 8 of the ~iltered water. Connection o~ the
o~erflow pipe 9 ie on the Illpper part of the filterO
Inlet pipe 10 ie provided for regeneratio~ of the
clog~ed iup filter~through the two cock~ 11 and 11'
of which the ~lurrying water jet i~ in~ctedO
~or sand remo~al ~rom the untreated water distri
buting gap following recirculation of the filter
column, the untreated wa~er-dietributing lower
~pace 13 with deflecting plato 12 ie developedO
For bac~washing the ~iltered water-co~lecting pipe 7
the return pipe 14 i~ connected to the outlet pipe
8, the front part of which is formed as a speed in~
crea~ing throat 150 . `
At 90 to the direction of water flow in the
tower ~ilter the per~orated divid~ng wall 16 i~
,e,ituated in the centxe plane o~ column 3, or in
its Yicinity9 with the aid o~ which the cleaning
process can be: restricted to the front part of the
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fil-ter column.
~ he track of the water to be filtered and t.l~ t
of the cleaning jets are marked in ~igures Io and 2.
Track "A" indicates the path of the water to be fil-
tered, and "B~,~ the path of the filtered waterO l'he
water jets recirculating the front part of filter
column 3, pa99 on track "C"~ ~;hi`le t~lose recirculat-
ng the rear part of column 3 pass on track "D", or
in their vicinity respectivelyO Arrows "E" show the
traok of the water.jet injected from the top down-
wards,.used for bac~wa~hing the collecting pipeO
The tower filter shown in Fig~res l a and 2,
i~ cleaned in the follow~ng way:
When the filter column 3 gets clogged up and
its regeneration becomes necessary~ entry of the
Wa ter .tO be filtered in 1;he inlet plpe 5 and its
exit in outlet plpe 8 are stopped, and the regene-
ration is started by conducting the filtered water
from abo~e at the rate~ o~ 5-l5.m~sec into the fil~
tered water-collecting pipe 7, through the re~urn
pipe l4, whioh rapldly accelerates to the effect
of throat 150 The ~iltered water is injected for
a ~ew seconds,~while~the ~lushing water flow~ at
: ~ high spe~ed into the parts of sand column 3 in the
vicinitg of collecting pipe 7,.and thereby not only
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the sieve 6urface of the collecting pipe gets
cleaned, but the thin sand layer too between the
collecting pipe 7 and rear wall 6 will be comple-
tely wa~hed outO
hereafter i~ cleaning of the more contami-
~ated front layer only becomes neces~ary in sand
column 3, then the bottom of the column i9 under- -
wa3hed with water jeta injected thro~gh the lower
space ~ 13 o~ the diatributing gap 2 via the
i~let pipe 10 in ~uch a way, that path o~ the water
jet~ should fit traok C. By proper adjustment of
the rat~ o~ in~ected water, only that part of.the
column participates in the recirculation, which is
in front of the per~orated wall 16, ~ollowing one
part o~ the reversed water jet~ passing on track ~1
through distributi~g gap 2; while the slurrying
other psrt of the water jet~ ~lowing back as a
result of the impact pressure, flowing on track
a2,washe~ back the filter grain~ passin~ downwards.
From time -to time, when xe~eneration of the
part of the ~Llter col~mn behind the per~orated walL
16 become~ neoe~a.ry, then the part of the filter
column 3 behind wall 16 is regenerated in such a
way~ that by tùrning off cock ll~ the flow ~elo-
city of the in~ected water jet i~ increased to
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it~ double ra-te throug,h the opcn cock ll, thu~ -the
slurrying w~-ter jets are forced to t~acks ~
~2~ whereby'recirculation and back~ashing of the
righ-t hand half of the rear grain column wlll
,take placeO On the other hand the lef`t hand'half
of the rear ~rain column i8 regenerated by opening
cock ll', and turning o~* cock llo The slurr~ing
water is discharged through overfIow ~ in both
caaes, carrying along the impurities wa~hed out
~rom the filter grains.
Finally after~cleaning the filter column as
described above, the recirculation is stopped,and
the water jet i9 injected into the lower sp'ace 13
'o~ the distributing gap 2, with which th~ sand ia
wash~td up and removed ~rom the distributing gap
by su~.table diatribution of the ~et. Thi~ way a
new f1ltering oyole m~y beglnO
The towex filter presented in Figures 30 and
40, i~ a preferable construction alternative o~
the inventio~, the tank of which is cylindricalg
and the untraatsd water distributi,ng gap 17 is
situated along the diame~ral plane of the cylind-
rical mantle 18~ At this solution two filter co-
lumns 3 and 31 and two ~lltered water-collecting
pipea l9 are positioned symmetrically to the dis~-
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ributing gap 17~ "F" in the I~`igure indicates the
track o~ the water conducted into the distributing
gap 17, ~hile "G" show~ the track o~ the water
flowing ou-t of the two inlet pipe~ 21 and 21'
used ~or injection.o~ the cleaning water during
regeneration of the ~ilter colL~ ~
Opera-tion and r~generation of the tower
~ilter according to the versi~n ahown in ~igures
3, and 4. 9 take place aa follows: The liquid
flowing through inlet.pipe 20 i~ uni~orml~ dist--
ributed horizontally and ver-tically in the direc-
tion of "~" arro~v~ in the untreated water distri-
buting gap 17, and ~lowing throu~h the gap~ between
the louvred panels 4 gets cleaned in ~ ter co-
lumns 3 and 3'~ then it passes out through the
~ilter collectlng pipe l~o l~hen filtor column~ 3
and 3' are clogged, the ~iltering is stoppea, in
.
:~ other words the entry through pipe 20 and e~it ~n
pipes 19 are stopped, and ~or th~ purpose of re-
` ~ æeneration recirculating water is conducted through
.
pipes 21~ 21' into ~ilter columns~3 and 3'~ Re-
circu1ation and backwashing of -the filter`~rain~ of ~ :
oolumn 3 with the liquid ~lowing on traak 8 take
place as before~ Removal of the sand from the dist-
. Fibuting gap 17 and backwashing o~ collectlng pipes 19
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can be carried ou-t as described before.
The equipment shown in Figures 3, and 4~, has a
favourable feature, in as much as it can function in closed
construction under pressure too, in which case it can be set
up under the ground surface as necessary, and this way it can
be located outside the building, or a substantial savin~ can
be attained in the height of the building intended for the
location of the tower filter.
The process and equipment of the invention can be
realized in several other construction forms besides that of
the described e~ample. The filter tank may be for instance
polygonal, it may be made of steel r aluminum, concrete, or
synthetic material. The filter units may be built into a
bloek, operated in series or parallel connection, depending
on the qualitative and quantitative requirements.
Regeneration of the filter may be started with re-
circulation too, flushin~ back the filtered water-eolleeting
pipe only afterwards, and what ;`s more, it is sufficient to
earry out the baekflushin~ at wèekly intervals. Oeeasionally
the filter may be regenerated by omitting the recireulation
and carrying out only the backflushing of the collecting pipe
and removal of the sand from the distributing gap twice or
three times in a succession. In case of several collecting
pipes, the backflushing can be carried out i`n pairs or separate-
ly too. By proper selection of the intensity and velocity of
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the wa-te.r je-ts, and by their application at the proper places,
effectiveness of cleaning the sand column can be increased
in the desired degree.
Application of the process and equipment of the
invention yields the following detail-advantages:
- the clean water collecting pipe of the filter can
be washed back within seconds, thereby the greatest problem
of the existing tower filters is eliminated, i.e. the problem
caused by clogging of the collecting pipes;
- as a result of -the high-capacity reversive slurry
recirculation and fast sand removal from the distributi~ng gap,
regeneration of the filter column takes a very short time, no
more than 10-20th part of the earlier cleaning time;
- time of the regeneration will be further reduced,
if the filter column is divided int:o two separately cleanable
layers;
~ since there is no neecl for the usual mam~oth pump,
compressor or watex jet pump e.ither, there is no narrow cross
section causing clogging;
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- no alumping sand or wa-ter space in the filter;
- the simple flat-bottomed tank fully utilizes
the space and filter medium;
- its simple, straight louvred panels - fitted
without overlapping ~ do not requir~ tooling, can
be manu~actured by a simple method;
- the ~lat-bottom constru~tion statically per-
mits the economic making of the unit in optional
~ize at conaiderable saving o~ the material utili-
zation;
- - no need for expensive pipe-cellar, because
the ~ilter is built on the gro~nd surface, or.
lowëred into the ground;
- ita.handling i~ ai.mple, ea~ily flutomated,
because it requires only t;he valves to be turned on
and o~;
~ ~t may be operated - de~ending on the quali-
tati~e requirementa - aa contact ~ilter, with chemi-
cal pretreatment~ prepuri~ication, or may be used
without these in the waste water puri~ication as wellO
The invention complately eliminates all the
. ~hortcominga o~ the presentl~ e~isting tower fil-
ter~) and ln addition the useful ~olume.too in-
creasea, w~ich built into a block would xeduce the
apace requirement to ~uarter of its aize, reducing
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the co~t of manuIact~r0 and inve~tment too by about
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