Note: Descriptions are shown in the official language in which they were submitted.
~ 320~3~
GAS-DISSOLVING METHOD
This invention rQlates to a gas-dissolving method which is
employed in charging a flexible container with liquid.
BACRGROUND OF THE INVENTION
In the canning and bottling industries there has been a trend
in recent years to substitute containers having flexible walls
for the traditional rigid steel ran and glass bottle, when
bottling or canning an artificially carbonated be~erage. The
pressure of the carbon dioxid~ in the head space of the sealed
container is suffiaisnt and essential in such instances to
prevent externally applied pressure deforming the bottle or
can during normal handling.
More recently, attempts have been made to extend the range of
uses of flexible cans by employing them as containers for non-
carbonated beverages. In order to create in the can aninternal pressure sufficient to prevent or resist permanent
deformation during routine handling and stacking, attempts
have been made to introduce a small volume of liquid nitrogen
into the head space of the can immediately before the can has
its lid fitted and joined thereto. The liquid nitrogen on
vaporisation undergoes a very substantial increase in volume
and is able to create a super-atmospheric pressure within the
can. Since, in typical industrial practice, a canning line is
capable of fitting lids to several hundred cans per minute, it
is necessary for each one of these cans to he charged with a
drop of liquid nitrogen. Difficulties arise in dispensing
drops of uniform size with the result that the internal
pressure in the cans tend to vary considerably one from
another. Some cans tend thus to be under-pressurised with the
result that they are readily deformed permanently during
routine handling while other cans are over-pressurised with
the result that the internal pressures causes deformation.
Notwithstanding the existence in the state of the art
, . .
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~'/LH/8711 ~32~93~
-- 2 --
of several ~ifferent liq~i~ nit~ogen di~p~nsing methcds ~Qr this
purpvse, no satisfa~tory solution to the problem of obtaining the
dispensing of drops o uniform si2e has yet been achieved.
In US Patènt Specifi~tio~ 4 347 695 ~here is ~isclose~ ~ metho~ of
bottling or canning a heverage which is in~ended to l~e use~ ~or
non-carbon~te~ ~eve~ages. Prior to its introduction into the bottle
or oan, the beverage has dissol.ved in it suf~icient "inert gas" to
strip dissolved oxygen from the beverage ~nd ~hen purge air from the
head space of the container. Sufficient gas is retained in the
beverage to exert a super-atmosphçric pressure internally of tne
container af~er i~ is sealed. The only inert gas disc10sed in the
Patent Specification for su~h ~se is nitrogen. ~e have dis~overe~
that when ni~ro~en is used in canning to cre~te a super-a~mospheric
pressure within a thin-wall~d can it is not pos~ible ~nder
~onventional oper~ting conditions t~ obtain internal pressures that
are ~onsistently ade~uate~ In particular, the kind of gas dissolver
employed in a conventional ~anning line is normally designed t~ be
operated a~ a pressure below 90 psig and some such ~as dissolvers do
not tolerate a pressure of ~ore th~n 7S psis. Mo~eover, while
conv~ntiona~ b~wl fillers a~e desi~ned to operate up to a maximum
pressure of 90 psig, the highest pressure that a thin-w~lled can i5
~esigned to withstand, it is prefer~ble ~o operate the fille~s at
pressures well below 90 psi~ so as to feduce wea~ and the resultant
nee~ fo~ frequent maintena~e. I~ is th~se factors which in p~actice
make it diEfic~lt to obtain ~dequ~te internal can pressures when
operating the method di~closed in US Patent 5pecification 4 347 695
~t norm~l am~ient te~per~t~re~. An i~provement m~y ~e obtain~d by
operatiny at bel~w ambient ~emperature but this practice r~uires
refri~ation to be provided and th~refore adds to the cost o the
canning ope~ation~ Although ~he ~bove discussion of US P~tent
Sp~cification ~ 347 ~95 has been m~de ~i~h regard to canning, similar
problems ~rise in ch~rging plasti~ bottles with liquid, particularly
if the bv~le has a capacity o 1 lit~e ~ less, and especially when
the b~ttle has a GApacity o~ a hal~ a litre ~e les~
- 3 - ~32 ~ 9 ~l~
UK Patent Specification 2 134 496 A discloses a method in
which a non-carbonated drink is canned in a "soft" thin-walled
can, for example an aluminium can, and a suitable internal
pressure is created in the can by pre-dissolving nitrogen and
a small amount of carbon dioxide in the liquid, and then
allowing nitrogen and carbon dioxide to come out of solution
in the sealed can. It is disclosed that the weight ratio o~
carbon dioxide to the drink is a predetermined value which is
not more than 15 : 10,000. However, even in such small
~uantities, carbon dioxide, which is a polar, acidic gas, can
have an appreciable effect on the quality or taste of the
beverage. Accordingly, we believe that the use of carbon
dioxide in addition to nitrogen in order to create an internal
pressure in a can or bottle is an unacceptable practice wheh
the liquid is intended to be still or non-carbonated.
SUMMARY OF THE INVENTION
It is an aim of the present invention to provide a method of
charging a flexible container with non-carbonated liquid which
enables an adequate pressure to be created internally of the
container without the need to charge the container to such a
level that the size of the head space becomes unacceptably
small.
According to the present invention there is provided a method
of charging a flexible container with non-carbonated liquid,
comprising dissolving an inert gas comprising argon in the
liquid at an elevated pressur~, charging the container Witll
the liquid in which said gas has been dissolved, and fitting a
closure gas-tight to the container, wherein the concentration
of dissolved gas in the liquid and the Yolume occupied by the
head space of the charged container are so selected that an
equilibration there is a super-atmospheric gas pressure in the
head space of the container (when measured at ambient
temperature).
., ,
J~
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~ /8711 1320934
By the term 'iner~ ga~ as u8el~ h~rein is meant a g~s or ~a~ mixtu~e
which is ta~teless, colourless and odourles~, and does r~ot re~çt
~heml~ally with ~he aid li~uid.
DE~AILED DE~}~IPIIVN V~' '1~; INV~;N'l'l(JN
___
~e inert gas com~risi~ argon is preer~bly pure argon. I p~re
a~on i9 not U~ the ga& preferably contaln~ a~ lea~t 509~ by volune
of ~gon ~nd typi~ally at lea~t 904 by vol~ne o~ ~rgon.
po~sible ~o mix wi~h the argorl One or more o~h~r inert gases, for
exalr~le, kryp'con or xenon.
e~
T~e accs~panying drawing illu~'crates ~ cor~ing ~o th~
invention and i3 a schematl~ ~lag~m of a c~nlng plant. ~e m~
accoxdlT~ to the pre~nt lnven~ion i~ ~L~tlc~l~rly u eful in the
~annlng of non~arbonated b~ve age~ ~nd we beli~ve Sh~t for the first
~ime i~ pr~vide~ a pr~ctic~ble method of Such canning in thln-walled
can3 which does not l ~ulr~ a ch~nge in ~e conventional practlce ln
~e a~ ~o ~ar a~ ~ne proportclon ot ~e ~om mer 1~ employed a~ head
3pace i~ re~uir~d while enablin~ the ir~rt ga~ co~ ing argon to be
di5solved ln th~ uid at a~ient te~r~tu~e and the container~ to
be ~illed at am~nt ~e~er~ture. Di~olution of an inert ga~
comp~islr~g a~on in l:he liquid ur~r pr~ure will cau~e an ~liquot
o ~h 9A~ wl~d ~h4 ran 1~ then ~h~qr~Pf~ wit.h F;l~h
llquld un~er pre~ure, typically u~ing ~ conv*nti~ owl filler,
and ~n ~ wi~rl f~ wl ~iLL~ t.hk pe~ re on
the llq~id 1~ r~lea~ed 'chQ~eby causlnq di~lved gas to st~r~ ~o c~re
out of ~olu~ion~ On 8eallng ~h* can, the ~a~ wlll continue to con~e
out 0~ 981lltiUrl cu~ hC hc~d ~p~ao ~ntil 3n 8~uilibrium i~
rea~ed b~een ~he g~ in the he~d 3pace ar~ ~he dissolved ~as in
the li~sid pha~e. Ih~ pre ~ure at equilibrlum at a given t~mperature
~ rea6e3 with de~reasin~ volun~e of head spaceO Ihe me~od ~ording
to ~he p e~nt invention enable~ an adequ~t~ internal pre~ure. ~at
.
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132~93~
least 15 psig at 16C), which renders the can resilient to
normal pressures exerted on it during routine handling,
without charging the can to such a level that the proportion
of the total internal volume of the sealed can occupied by the
gas space at the head of the can (i.e. the head space) is less
than that conventionally employed for a can of given aspect
ratio (i.e. the ratio of its height to diameter). Typically,
the proportion of the volume of the can occupied by the head
space is at least 5% of the total internal volume of the can.
The method according to the present invention may also be u~ed
to charge plastic bottles with non-carbonated liquid, in
particular, it enables bottles containing non-carbonated
liquids to be formed of the materials and with the wall
thicknesses currently employed in the bottling in plastic
bottles of carbonated beverages.
Preferably sufficient inert gas comprising argon is dissolved
in the liquid to create in the sealed container an equilibrium
pressure in the range og 15 to 20 pslg at 16C, though if
desired higher internal pressures may be created.
The method according to the invention may be used to can or
bottle a wide range of different non-carbonated drinks. It
may for example be used to can or bottle fruit juices; still
wines or other non-carbonated alcoholic beverages; soup; milk
and other pourable dairy products; and liquids, e~g.
beverages, such as naturally fermented ales, which have
relatively low levels of carbonation inadPquate on their own
to generate the necessary internal pressures.
The method according to the invention may also be used to can
foodstuffs in a liquid, syrup or sauce, in which instance the
argon is dissolved in the liquid syrup, juice or sauce.
, ,;~
~32~93~
- 5a
The method according to the present invention may also be
employed in charging with liquid containers that, like cans,
are generally right-cylindrical in form but which are formed
of other flexible material than metal.
..~..,
M~/LH/8711 132~93~
.. ~
The pres~ure und~r which the ga~ 1~ dissolved in ~he li~uid ls
preferably at least equal to that under which th~ container i5
charged with the liquid. Preferably, a ~m~11 excess press~re i8
employed 80 a~ to enable ~ransfer of the liquid ~rom a g~s dis501vlng
vessel to the iller to be ef~e~ed by pres~ure ~r~n~er without ~he
t~ y A Meeh~l9el~ ho dl~ol1J~r 2~1 thQ
filler.
The liquid i~ preferably ~turated with the inert gas comprl~ing
a~gon a~ the ~hosen p~e~æUre. Any co~ven~ional mean~ o di~solving
th~ 9A# ln ~h~ liquld may he ~ y~. Fhr Px~mpl~l th~ di~olYe~
may ~o~prl~e a pre~sure tan~ ad~pted to be ~h~r~ed with the liquid to
a ahosen l~v~l and being fitt0d with mean~ for in~r~ducing ga8 into
~hc liquld, ~ho arr~gomQ~ in~ ~ch that u~dl~901~d ga~ en~er~
~h~ head cpac~ o the tanX~ qhe tank may ~e prsvided wlth on~ or
~e dl~fuser~ ~t or n~a~ its bo~om which are pl~ced in
coq~r~ ;ion with ~ ~ource unde~ pre~ure of the lner~ ga~
cwr~ri~ argon ~o ~ ~o ena~le ~h~ ga~ to be in~roduced lnto the
li~uid in th~ ~orm of ~ine bubbles.
qhe pressure un~er which the ~ont~inPr i~ ~iLled ln accordance with
the invention 1~ ally not graaSer ~an ~hat whlch would cau~e
perman~nt defor~tion o~ ~he cont~ine~. In the instan~e of
thinowall~d ~an~ ~ur~ently in use ~n thç c~nning indu~t~y, thi~
pre~sure ~hould no~ ~2 in exce~3 of ~0 psig. Preferably, th~ illing
p~e~ure i~ in ~h~ range 45 to 75 psig, ~nd hen~e the pre~s~re under
~hioh thE iner~ ~8 comprising ~r~on i~ ~i3solved ~8 in thij range.
Typical~y, a conven~ion~l bowl ille~ i~ employed to ch~rg~ the cans
~L LuLLl~ w~ . Ih~ h~t ia ~ls~ol~cd in ~ho liquid ic
pr~erably 3upplied dir~ o the ullage spaCe of the bowl ~lller.
Surp~i~in~ly, we ha~ ou~d it possl~le to u~e ni~ro~en ~n~aad o
lner~ g~ pri~ing argon or thi~ purpo~e while still ob~aining
Adequate in~nal pre6sur~s,
~ 32033~
Typically, once a can or bottle has been charged with liquid
under pressure, it is released ~rom the filling apparatus and
is transferred to a sealing station. This procedure involves
release of the pressure exerted on the liquid in the filler
and thus gas starts to come out of the solution in the liquid
in the can or bottle. In the example of canning, we prefer to
blow or direct into the head space of the can inert gas
comprising argon or, more preferably, nitrogen immediately
prior to the sealing of the lid to the top of the can (which
operation is preferably performed by a conventional seamer).
It is advantageous to use nitrogen rather than argon for
performing such a head space purge. On a qualitative basis,
this can be understood by considering the equilibrium of the
gas between the liquid phase and the gas phase in the can once
it has been sealed. Suppose, immediately upon sealing of the
can the composition of the gas in the head space is 100~ argon
at a pressure of 1 atmosphere absolute. Suppose also that at
the filler the liquid is saturated with argon at a pressure of
atmospheres. The argon thus comes out of the solution and
continues to do so until equilibrium is established betwe~n
the partial pressure of argon in the gas phase and the partial
pressura of argon in the liquid phase. Suppose now that at
sealing of the can, the atmosphere in the head space consists
of nitrogen at 1 atmosphere. In this instance there is no
partial pressure of argon in the head space immediately upon
sealing. Accordingly, more argon needs to come out of the
solution from the liquid and enter the head space of the can
before eguilibrium is established. Accordingly, the use of
nitrogen instead of argon to purge the head space of the can
immediately prior to seaming enables a high internal pressure
to be achieved at equilibrium.
Referring specifically to the drawing, yas was passed from a
pipeline 4 into a volume of water in a gas dissolver 2 of
~2~3~
- 7a -
conventional kind and the water saturated with the gas at
ambient temperature. The water containing the dissolved gas
was then passed from the dissolver 2 via a pipeline 8 to a
bowl filler 6 having a single head and being
~,,r
~:'`
~/~I/B7ll 132093~
adapted or labora~ory use. A plp~lir,e lO was provided ~or supplying
~a~ to the he~sp~ce of the bo~l filler 6. Cans each nomin~1.1y ~f
44Q ~ apacity, were filled one at a t~lTe with the water at anbient
tem,erature. In ~aoh ex~ar~n~; ~uf~icl~nt water wa~ ~atur~tcd wlth
gas ~o enable fou~ c~ns to be fllled. O~e filled, ea~h carl was
i~nediately ~ran~ferred m~n~aliy 'C4 a conv~ntio~al ~eam~r 12 ad~p~Rd
fo~ oratory ll~e.
Gas qa~ ~upplied frorn piFeline l~ across the tnouth of each can at
~ient te~ al;ure before ~it~ing and 'æeaming' a lid to each
respectiv@ can ~thi~ practice being known as 'under c~ver g~sln~').
~o ~nc ~r~ ~llow~ f~r ~ hm~rFi ~ that the ~gs~e
int~rnally thereof woUld be able ~co equilibrl~e and ~en the
lr,ternal pre~u~e of the car" an~ te~nperature ~nd volum~ of the
w~ter ~n~reln Were mea~urec~.. ~e ~ull;~ ..LJL~ s~t oul: kelow
~n Table 1 ar~l 2.
~1/I~1/8711
~ 9 " IL32093~
TABLE 1
Gas blown
Gas ~8 GAS acros~ can
p~e~ure in Ga5 pressure ln supplied mouth (~t
EKa~ple dlssolver 2 ~upplled to bawl filler to bowl 10 in water
~ber p~ig dlssolvo~ 2 6/p~lq filler gauge)
120 N~ 60 N2 N2
2 60 Ar 60 ~ Ar
3 90 ~ 90 Ar Ar
4 60 A~ 60 N2 N2
Ar 90 N2 N~
6 120 A~ 90 N2 ~:2
7 60 Ar ~0 Ar N2
8 90 Ar ~0 Ar N2
9 120 Ar 90 Ar N2
Ar 7S N~ N2
~/~i~8711
lO- ~32093~
TA~LE 2
E~uilibrl~ted Ibmperature o~ Volusne o~ water
Exarnple ln~ c~ln con~r~l9in alm
N~e~ p~ig C c~3
1 (a) 12 ambient 4~5
(b) 12 anJ~ t 435
(c) 12 an~lent 435
2 (a) 1~ 15, 9 43S
~) lg 15 . 9 4~0
(~) 19 15.9 ~0
td) lB.5 15.9 43~
3 la) 24 lS~ 0
(b) ~4 15 . 8 440
) ~4 15. R 4313
(d) 24 15. ~ 440
(a) 17. 5 21 440
tb) lÇ . 5 21 430
lo) 16 ~ o
(d) 16~ 5 21 43û
!~) ' 22 20 435
~b) 24. 5 20 440
(~ 24 20 44~
(d) 24 20 440
~ /871~
11- 132~3~
E~uilibrlated ~mperature o~ V~ of water
~rrple ~y~ san control in ~an
N~ p~ig ~C cm~
6 ~a) ~5 1~ . 8 4~0
(b) ~5 15. 8 441~
~c) 25 15 . 8 440
(d) 25 15. 8 440
7 (a) 16 19 435
(b) 16 1~ 435
tc~ 16 lg 43$
~d) 16 19 435
8 ~a) ~6 19 435
~b) 26 19 435
6 lg 435
~d) 26 lg 43S
g ~a) 2~ 19 435
~ ~b) 2~ 19 435
~5) Z!6 lS1 43S
(tq) ' 3~ 0
lO(a) 18 16.~ ~35
18 1~. ~ 435
~) 16 16. ~ 435
~d) 20 1~. 8 434
