Note: Descriptions are shown in the official language in which they were submitted.
~2089~2~
- - 2 - HOE 82/F 074
It ;s a generally known fact that flu;ds ;n turbu-
lent flow experience drag at the walls conta;ning them.
It is also known that this drag can be reduced by ad~ing
small amounts of certain substances. Substances wh;ch
have th;s effect are referred to as dra~~reducing agen-ts.
A drag-reducing agent is a substance which, added ;n a
small amount to a liqu;d in turbulent or pulsating flow,
enables this liquid - under otherwise identical condi-
tions ~ to flow fasterr Drag-reduciny agents have the
effect that a given pump can deliver more l;quid through
a g;ven pipe.
In many cases this fact alone represents a tech~
.
n;cal benefit, for example when a p;pe is used to full
capac;ty in normal operation and peak demand would have
to be delivered at certain t;mes. Since a given pump per-
~ormance can deliver more liquid when drag-reduc;ng agents
are used, the associated saving in energy will also, in
many cases~ produce a techn;cal benef;t. F;nally, ;f
there is no wish to increase the flow rate, th~ use of
drag-reducing agents makes it possible to reduce pressure
loss or to use pipes which have a smaller cross-section.
Both possibilities are measures wh;ch can improve the
econom;cs o~ operating a pipe.
Drag-reduc;ng agents d;sclosed for water or aqueous
solut;ons are not onLy high molecular ~eiyht compounds,
such flS polyethylene oxide or polyacrylamide,. but also
solut;ons of some surfactants. Additions of high molecu-
12~18~2~
- 3 ~
lar we;ght compounds have, however, onLy a lim;ted prac-
t;cal use as drag-reduc;ng agents, since, ;n regions of
high sheer and stress~ such as~ for example~ ;n pumps or~
to a minor extent, in the turbulent boundary layer adja-
cent to the walls of a pipe, they are mechanically degra-
ded and suffer an ;rreversible loss ;n the;r effectiveness
as dra~-reducing agents. High molecular weight add;t;ves
are therefore unsu;table for closed water circulation sys-
tems, where the same aqueous solut;on is constantly pumped
round a system of p;pes, s;nce the ;rreversible mechan;cal
degradat;on necessitates cont;nual replen;shment w;th
effect;ve high molecular we;ght substance.
As is knownf add;t;ons of surfactants ~o vater do
not suffer from the disadvantage of irreversible mechani-
cal degradat;on ~U~S. Patent 3,g61,639~ It ;s true thathere too there ;s some mechan;cal degradat;on ;n regions
of very h;gh sheer and stress~ such as, for example, in
pumps, but ;t ;s completely revers;ble as soon as the
solution has passed through these reg;ons. For ;nstance,
Sav;ns has descr;bed the drag-reduc;ng effect of an aqueous
solution of Na oleate on addition of KCl + KOH or NaCl+NaOH
(Rheol. Acta 6, 323 (1967D. Asslanov et al~ (Izv. Akad. Nank.
SSSR, Mekh. Zh;dk. Gaza 1,36-43 t1980~ stud;ed inter alia,
aqueous solutions of Na laurate, myristate, palmitate and
steara~e a~ pH 11 for drag-reducing purposes.
Chang et al. (U.S. Patent 3,961,639) describe the
drag-reducing effect of aqueous solutions of some nonionic
surfactants containing foreign electrolyte, at tempera-
tures near the cloud po;nt.
. . - , ~ , : . ~
120~34;~ 1
~ 4 --
Sign;ficant disadvantages of the surfactant solu~
tions ment;oned are the;r relat;vely h;gh use concentra-
t;ons, of at least 0.25% by weight, the formation of in-
soluble soaps with Ca2+ and other cations, the forma~
tion of two phases ~Ihich separate on prolonyed standing
and can lead to blockages, the need to add corros;on-
promoting foreign electrolytes, and a very narrow tempera-
ture range~ of a few degree Centigrade over which the drag-
releasing effect occurs. Aqueous solutions of some cat;on
surfactants, such as, for example, cetylpyr;dinium brom;de
(Inzh. F;zh. Zh. 38, No. 6, 1031-1037 ~1980)) or cetyl
trimethylammonium brom;de (Nature 21~~ 585-586 (1967)),
each ;n a 1:1 molar mixture with ~ -naphthol, are free of
these disadvantages~ but they have the crucial d;sadvan-
tage, in addition to ~he fact that ~ -naphthol is spar-
;ngly waterosoluble, that such m;xtures lose the;r effec-
tiveness as drag-reducing agents with;n a few days, as a
result of chemical degradation (U.S. Patent 3,~61,6~9,
Conference Proceed;ng: Intern. Conference on Dra~ Reduc
tion, ~.-6th September 1974, Rolla Missour;, U.S~A.).
We have now found, surprisingly, that, unl;ke any
ex;sting surfactant disclosed for use as a drag reducing
agent, the compounds listed below are effective drag-
reducing agents ~Jhen used ;n the pure state ;n aqueous
solutions even in very low concentrat;ons and without any
add;tive whatsoever.
The invention accordingly relates to a process
for reduc;ng the drag of aqueous med;a ;n turbulent or
pulsatiny flow~ wh;ch compr;ses add;ng to the aqueous
.
~ 0~342~
~ 5 --
medium a compound of the formula
R 1 -K~A~3
;n which K denotes a group of the formula ~N ~ or
- N(R2)3, , R2 denotes C1-C3-alkyl, preferabLymethyl,
A denotes an an;on of the follow;ng formulae
COO ~
COO ~
O~ , al , R3-CQ0~ , SCN~ , CH ~ -S03~
Hal denotes fluor;ne, chlorine~ bro~ine or ;od;ne, R3 deno~es
C7-C10-alkyl or C7-C10-alkenyl and ;f A ~ thio-
cyanate~ R1 denotes C1~-C26-alkyl or C16 C26 alkenyl~
;f A = p~toluenesulfonate, R1 denotes C12-C2~-alkyl or
C12-C26-alkenyl, and if A has one of the rema;n;ng
meanings R1 denotes C1~alkyl or C16-alkenyl.
The surfactant salts of the follow;ng cat;ons and
an;ons are part;cularly preferred:
. ~
fC16~33NtCH3)~ ~ or ~ 16H33
COO~ ~~~, COO~
w.ith the an;on ~ or
~0~ Hal = Cl., Br,~
or xH2x~ 1 C fo-r 7~ x lO
~ ~nH2n~lN(CH3) ~ ~ H2n+1 N ~ ~
a) with the ar-ion 3 ~ S0'3~ for 12 - n ~ 26
. b) with the anion SCN~ for 16 ~ n - 26
~25)~342~L
- 6 -
The salts mentioned are suitable for reducing the
drag of aqueous media. They are added in concentrations
of 0.01 to 2, preferably 0~06 to 0.6% by weight, but each
salt has a d;fferent lower cr;t;cal concentrat;on l;m;t
for adequate effectiveness as a drag-reducing agent. The
drag-reducing effect also depends on the temperature.
Depending on the salt used, an adequate drag-reducing
effect is found ~lithin the temperature range from 0C to
100C and above 100C. The lower temperature l;mit
for use as a drag-reducing agent is for all surfactants
the solubility temperature. However, if the surfactant
is ;n solut;on, the operat;ng temperature can be below
the solub;l;ty temperature by S - 30~C for some hours
to weeks.
.
For n-hexadecyltrimethylammonium sal;cylate (CTA-
Sal), adequate drag-reducing act;v;ty is obta;ned ~ith
concentrations of 0.01 to 2% by wei~ht~ preferably 0.05
to Q.SX by we;ght, w;th;n the temperature range from ~5
to 70C~ At the same concentrat;ons as the sal;cylates~
the halogenobenzoates have a drag-reducing activ;ty within
the temperature range from 35 to 65C. For pyridinium
compounds the preferred temperature range is about 8 to
12 lower than that of trirnethylammonium salts. For the
purposes of the invention, halogenobenzoates are the
fluorine, chlorine, bromine and iodine derivatives, and
they are preferably chlorobenzoic and bromobenzoic acid.
The surfactant salts of the formula shown above have been
extens;vely described ;n the literature~ for example, in
Journal of Coloid and Interface Science Vol. 75, Page 575.
~208~
-- 7
For n alkyltr;methylammon;um thiocyanates (CnTA-
SCN) the ~ollow;ng ranges for max;mum drag-reduc;ng act;-
v;ty were found: n-hexadecyltrimethylammon;um th;ocyanate
within the range from 0.02 to 2% by weight, preferably
from 0.06 to 0.6X by weight~ w;thin the temperature range
from 45 to 65C; and n~octadecyltr;methylammonium th;o~
cyanate with;n the range from 0.04 to 2% by we;ght, pre-
- ferably from 0.09 to 0.9X by we;ght, within the tempera-
ture range from 55 to 75C, preferably from 60 to 70C
The gener~l rule is that the temperature range with;n
wh;ch there is adequate drag-reduc;ng act;vity ;s sh;fted
by about 10 15C to h;gher temperatures w;th every
add;tional C2-H4 group. In the case of pyr;d;nium
compounds, the preferred temperature range is about 5
15 15C lower than, and the requ;red concentrations 1.5 to
tw;ce as much as, that of trimethylammonium compounds of
the same cha;n-l;nk.
For n-alkyltrimethylammon;um p-toluenesulfonates
the follow;ng ranges of max;mum drag-reduc;ng activity
were found:
n - 12 : 0.1 to 4% by weight, preferably 0~3 to 2X by
~ ei~ht, for 0 - 15C.
n ~ 14 : 0.05 to 2~ by weight, for 5 to 30C.
n = 16 : 0.05 to 2% by weight, for 15 to 45Cn
n = 18 : 0.05 to 2% by weight for 30 to 60C.
There is a very general rule that every additional
C2H4 group causes a shift in maximum drag-reducing
act;v;ty by 10 ~ 15C to higher temperatures. The
- corresponding pyridinium compounds have drag-reducing
..-
` ~L2V~342~
-- 8 --
activity at concentrations which are higher by a factor
of 1.5 to 2 and at temperatures wh;ch are lower by 5 to
1 5C
Both the toluenesulfonates and the thiocyanates
have drag-reducing activity even at temperatures above
100C when combined w;th n-alkyltrimethylammonium com-
pounds having cha;ns wh;ch are at least 20 to 22 carbon
atoms long.
For the group of compounds which have the s~ructure
10 ~C16H33NtcH3)3] ~CxH2x~1COO]~, the limits for
- ~aximum drag-reducing activity are as follows:
x = 7 : 0.08 to 2X by weight, preferably 0.2 to 1% by
weight f rom 20 to 45C
x = 8 :0.05 to 2% by weight, preferably 0.1 to lX by
~eigh~ f rom 20 to 60C
x = 9 : 0.05 to 2% by ~le;ght, preferably 0.1 to 1X by
~e;ght from 20 to 70C
x = t~: ~.OS to 2X by weight, preferabLy 0.1 to 1X by
weight f rom 40 to 100C preferably 50 to 90C
In the case of the analogous pyrid;nium compounds,
the maximum l;mits in respect of the concentrations in-
crease by a factor of 1.5 to 2 and decrease in respect of
the temperature ran~e by 5 - 15C.
We also found that increasing the pH of the
aqueous solution to pH values above 9, in particular to
pH 10-11, by adding NaOH or other bases, or by adding
Na~C03 or other saLts which raise the pH value, signi-
ficantly improves drag-reducing activity at the same sur-
- factant concentration. A reduction in the pH value by
~zas4~l
means of HCl or other strong acids to pH values not
greater than 4.5 also leads to an improvement ;n drag-
reduc;ng act;vity.
The drag~reducing effect can also be strengthened
by adding other foreign electrolytes. Examples of such
suitable foreign electrolytes are weak acidsr such as
acetic acid or form;c acid, and salts which are formed
from the following ions: alkali metal, alkaline earth
metal, transit;on metal, ammonium or aluminum cations,
hal;des,
CLO3~, ClO~ BrO3~, JO3~, S032~, S2O3-~, S042~,
2 8 2 ' 3 ~ pO4 , CO3 ~, CH3COO~, C2O
The amount of these foreign electrolytes uh;ch
can be added to strengthen the effect ;s lim;ted at the
upper end by the concentration at which there is a salting-
out effect for the surfactant. There ;s no concentration
lim;t at the lower end.
The effects of the fore;gn electrolytes also de-
pends on the valency of the ;ons, the effect shifting to-
ward lower concentrations according to the following
series: 1-1-valent electrolyte ~2-1~valent electrolyte
~1-2-valen~ electrolyte ~ 2-2-valent electrolyte c~3-2-
valent electrolyte C2-3-valent electrolyte. The improve-
ment in dra~-reducing activity is particularly marked on
add;tion of a salt ~Jhich simultaneously raises the pH
value to pH~ ~.9. For example, the addit;on of Na2C03
- is particularly favorable w;thin the concentrat;on range
- ~2~38~
- 10 -
0.1 x C ~ C ~ 10 x C ;f C ;s the molar concentration of
the surfactant used.
Instead of add;n~ salts, ;t is also possib~e to
proceed by~ for example, using a cety(trimethylammon;um
halide or cetylpyridinium halide in a molar ratio of 1:1
together ~I;th an alkal; metal salt of sal;cyl;c acid or
a halogenobenzo;c ac;d as drag-reduc;ng agent~ The effect
obtained is then equal to the effect obta;ned with cetyl-
ammonium ben-~oates in the presence of alkal; metal halides~
The max;mum drag-reducing activ;ty also depends
on the time s;nce the preparat;on of the aqueous solut;ons
of the cetylammon;um or cetylpyr;d;nium benzoates. Al-
though the surfactant solut;ons have a drag-reduc;ng ac-
tiv;ty immed;ately `after the solut;ons have been made up,
this activ;ty can change markedly in the course of a ~eek.
The t;me requ;red to obtain max;mum act;v;ty can easily
~e determ;ned for a part;cular case by s;mple exper;ments.
In most cases, max;mum act;v;ty is reached at the end of
one week~ After th;s time there ;s no further change or
;mprovemel-t ;n the act;vity.
The surfactants ment;oned were mostly texcept;on:
Examples 12 and 13) tested for their drag-reducin~ acti-
v;ty ;n a customary manner by measur;ng on the particular
aqueous surfactant solution the pressure drop ~ P over the
len~th L on flow through a tube of cross-section d for
various veloc;ties of flow u. These values can be used
to calculate the dimensionless quant;t;es, the drag coef~
f;cient ~ and Reynolds nu~ber Re:
: . . .. : ., :,,
~2~842~
.
- 11 -
` 2 d ~ P
~ u' L
Re= u d
. ~
where ~ denotes the density and ~r denotes the kinemat;c
viscosity. It ;s customary to ;nsert for p and r the
correspond;ng values of the pure solvent, namely of water.
The ~ and Re values thus obtained For the surfactant
so~ut;ons s~ud;ed were compared ;n the customary log-log
plot aga;nst Re with the correspond;ng values for pure
~ater g;ven by
1/~?_ ~ 2 log Re ~ ~ 0,~ .
10 Drag-reduct;on, or effect;veness as drag-reduc;ng agent
~DR)~ per~ains when ~ HzO ~ ~DR ~ ~ and the s;7e of
the drag reduct;on, ;n percent~ is g;ven by:
H2O SB
= X drag reduction = ~ x 100
}1~0
As can be seen from F;gure 1, the sa;d surfactant
15 solutions act as drag-reduc;ng agents ;n such a way that
the percentage drag reduct;on increases with ;ncreas;ng
Reynolds number~ but that beyond a certain Reynolds number,
Rema~ with max;mum percentage drag reduct;on~ it decrea~
ses very rap;dly. A surfactant solution's drag-reducing
20 activ;ty will be character;zed below by the magnitude of
Remax; a surfactant solution with Re~ax = 20~000 accor-
-; d;ngly ;s more effect;ve as a dra~ reduc1ng agent than a
,
~0~
- 12 -
surfactant solution with Remax = 10,000. The assoc;a-
ted ~ -value is desi~nated d max The studies of the
surfactant solutions only gave reproduceable results ~hen
the aqueous solutions of the surfactant salts had each
been stored for about one week before the measurements at
the measurement temperatures. It is true that the solu-
t;ons showed drag-reduc;ng activ;ty even immed;ately after
having been made up but the drag-reducing act;vity can
show a marked change within the course of one week.
The surfactants thus pretreated were subjected to
a large number of tests. For instance, extended tests
over several days demonstrated, as can be seen from Exam-
ples 11 and 13, that the drag-reducing activ;ty of the
sur~actants listed is not subject to mechanical or chemi-
ca~ degradation. We also found that the drag-reduc;ng
activ;ty of the surfactants mentioned increases with
;ncreas;ng concentrat;on; however, the v;scos;ty of the
solut;ons also ;ncreased, so that the percentage drag
reduct;on becomes poorer at relatively low Reynolds numbers
~cf~ F;gure 1~. However, we also observed that the thermal
stabil;ty of the surfactant solut;ons ment;oned, ;.e. the;r
drag-reducing act;vity at high temperatures, increases
with increasing concentration ~cf. Examples 1 and 2).
The thermaL stability ;s not only determ;ned by the con-
centration but also by the surfactants themselves; forinstancep the tests showed that the temperature range over
which there ;s drag reducing activity is generally slightly
lower ~8 ~ 12C) in pyr;d;nium compounds than ;n tr;-
.
- methylam~onium compounds.
~ZV~2~
- 13 -
The stud;es carried out show that the surfactant
salts mentioned are useFul as drag-reducing agents wherever
water is pumped through p;pes, but in particular where
water is constantly pumped ;n a cycle through a p;pe net-
work, as, for example, ;n cool;ng cycles, s;nce th;s par-
t;cular application of necessity requires the drag-reducing
agent to have substantial long-term stability, which is
what the said surfactant salts have~ The surfactant salts
can be metered into the water flowing through the p;pes
not only ;n the form of a concentrated surfactant solut;on
tl 10% by wei0ht) but can also be added as pure crystal-
line surfactant salts. Ow;ng to the effic;ent mixing
effect, the most su;table place for meter;ng ;nto the pipe
network ;s shortly before a pump.
Example 1
Hexadecyltr;methylammon;um sal;cylate (abbrev;ated
below to CTA-Sal) was made up ;nto concentrat;ons, in
dem;neralized water, of 130, 150, 200, 300, 500, 750, 1000,
1500 and 2000 ppm by we;ght by we;~h;ng 0.13, 0~15, 0.2,
0.3~ 0.5, 0.75, 1.0, 1.5 and 29 of CTA-Sal ;nto 1000g of
dem;neralized water. The salt was dissolved by stirring
at room temperature, and the solutions were briefly heated
to about ~0C, cooled down to 2ZC and stored without
stirr;ng at th;s temperature for 1 week.
2~ They were then tested for drag reduct;on ;n a tur-
bulence rheometer (Polymer Letters ~,851 (1971)~ by ~orc;ng
1.5 l;ters of liquid w;th a p;ston through the measuring
p;pe as in a hypodermic needle. The p;ston is acclerated
dur;ng the measurement, so that an ent;re flow curve
.. ~ . -
~20t34Z~
- 14 -
as sho~n ;n F;gure 1 is recorded ;n one measurement. The
diameter of the measuring pipe is 3 mm, the length over
which ~ P is measured is 300 mm, and the inlet section is
120n mm long.
S The same CTA-Sal concentrat;on ser;es was measured
in this apparatus at 22C and 52C after the solution
had also previously been stored at 52C for one week.
Figure 1 shows the flow curves for CTA-Sal at
l50, 750 and 1500 ppm. Tables 1 and 2 summarize the re-
sults of all measurements for 22C and 52~C in the
form of Remax and ~max
Example 2
Solut;ons of hexadecylpyr;d;n;um sal;cylate in
uater were prepared at the concentrat;ons of 200, 250, 300
SOO and 1000 ppm, and ~ere ;nvest;gated ;n the turbulence
rheometer at 2SC and 40C for drag reduction in the
manner described ;n Example 1. As can be seen from Table
30 there is a marked drag-reduc;ng effect at 25C from
300 ppm and at 40QC from 500 ppm.
~ e~
Ident;cal solut;ons conta;n;ng a CTA-Sal concen-
trat;on of 750 ppm were made up as in Example 1~ adjusted
to pH 3.2, pH 4~2r pR ~.95, pH 7.~, pH 10 and
pH 10.9 w;th HCl for pH C 7 and NaOH for pH ~ 7,
and measured at 22C ;n the turbulence rheometer.
HaOH and HCl were added before the solutions were heated
up to 9nc, and the pH valuès were measured immediately
before the measurement in the turbulence rheometer. As
the results ;n Table 4 show, the adjustment of the pH
~;~0~342~
~ 5 -
value to pH ~ 4.2 and pH ~ 10 g;ves a marked improve-
ment in dra~-reducing activity compared with an equal
strength solution of pure CTA~Sal, as the comparison with
Example 1 shows.
E mpLe 4
Various amounts of NaCl were made up .ogether with
CTA-Sal as described in Example 1 to aqueous solutions
whose CTA-Sal concentrat;on (in mole/liter~ was in every
case 750 ppm t1~78 x 10 3 mole/liter) and NaCl concen-
tration as follo~s:
1 x 10 4, 5 x 10 4, 1 x 10 3, 1.8 x 10 3, 5 x 10 3,
0.01~ 0.05, 0.1, 0.35, 0~7 and 1Ø
The results of the investigation of drag reduction
at 22C in the turbulence rheometer are summar;zed in
Table 5. As can be seen from Table 5, addit;on o~ NaCl
in up to a S0-fold molar excess improves CTA-Sal's drag-
reducin~ activity.
Example S
By means of the method descr;bed in Examples 1
and 4, aqueous solutions were made up to conta;n ;n each
case 750 ppm (1.78 x 10 3 mole/l;ter) of CTA-Sal and
the following Na2C03 concentrat;on (in mole/liter):
1 x 10 ~, 2 x 10 4, 1.78 x 10 3, 6 x 10 3, 0.02 and 0.1.
The results of the investigat;on of drag reduction
2S in the turbulence rheometer at 22C are summarized in
Table 6. Even the addition of only 2 x 1~ 4 mole of Na2C03
per liter combined w;th an increase in the pH of the
solution to pH 10 g;ves a marked improvement ;n drag-
reducing activity compared with a pure 1.78 x 10 3 molar
~ 8~
- 16 -
CTA-Sal solution ;n water,
Example 6
By means of the method described ;n Examples 1
and 4, aqueous solutions were made up to contain ;n each
case 75Q ppm ~1.78 x 10 3 mole/l;~er) of CTA-Sal and
the following CaCl2 concentration (in mole/liter):
1 x 10-4, 3 x 10-4, 1 x 10-3, 1.78 x 10 3, 4 x 10 3,
0.01, 0.1 and 0.5.
The results of the investigation of drag reduction
in the turbulence rheometer at 22~C are summar;zed ;n
Table 7. There is a marked improvement ;n drag-reduc;ng
act;vity compared w;th a pure 1.78 x 10 3 molar CTA-Sal
solut;on ;n water at CaCl2 concentrations within the
range from 3 x 10^4 to 0.1 mole/liter.
Example 7
By means of the method descr;bed in Examples 1 and
4, aqueous solut;ons were made up to contain in each case
750 ppm (1.78 x 10 3 mole/liter) of CTA-Sal and the
followin~ Na2S04 concentrat;on tin mole/lit2r):
1 x 10-4, 2 x 10-4, 3 x 10-4, 1 x 10-3, 1.7~ x 10~3,
4 x 10 3, 0~01 and 0.1.
The results of the ;nvestigation of drag reduct;on
;n the turbulence rheometer at 22C are summarized ;n
Table 8. There ;s a marked ;mprovement in drag reducing
activity compared with a pure 1n78 x 10 3 molar CTA-Sal
soiution in water at Na2S04 concentrations within the
range from 1 x 10 4 to 0.1 mole/liter.
Example 8
.
By means of the method described in Examples 1 and
~Z~84~Z~
- 17 ~
4, aqueous solutions were made up to contain in each case
750 ppm (1.78 x 10 3 mole/liter) of CTA-Sal and the fol-
Low;ng MgHpO4 concentration ~in mole/l;ter~.
8 x 1~-5, 1 x 10-4~ 2 x 10-4, 6 x 10 4, l x 10 3,
and 1.78 x 10 3~
A precipitate forms at M~HpO~ concentrations from
x 10-3 mole/l;ter. The results of the ;nvest;gation
of dra0 reduction in the turbulence rheometer at 22C
are summar;zed in Tab(e 9~ There ;s a marked improvement
;n drag-reducing activity compared with a pure 1.78 x 10 3
molar CTA-Sal solution in water at MsHpO~ concentrat;ons
with;n the range from 8 x 10 5 to 1.8 x 10 3 mole/L;ter.
Example 9
By means of the method descr;bed ;n Examples 1 and
4, aqueous solutions were made up to contain in each case
750 ppm (1.78 x 10 3 mol-e/liter) of CTA-Sal and the
following Fe2(S04)3 concentration S;n mole/L;ter):
5 x 10-5, 1 x 10-4, 2 x 13-4, 3 x 10-4.
A prec;p;tate forms and drag~reducing activity de-
creases for an FE2(S0~)3 concentrat;on from 3 x 10 4mole/L;terO The results of the invest;gat;on of drag
reduction in the turbulence rheometer at 22C are sum-
mar;zed in Table 10. There ;s a marked improvement in
drag-reducing activity Gompared with a pure 1.78 x 10 3
ZS molar CTA-Sal solution in water at Fe2(S04)3 concentra-
tions w;th;n the range from 5 x 10 5 to 3 x 10 4 mole/
liter.
Example 1D
By means of the method described in Examples 1
~ r .
~20~
- 18 -
and 4, aqueous solutions of hexadecyltrimethylammonium
m-chlorobenzoate were made up in concentrations o~ 2000 ppm
and 5000 ppm by weighing out equimolar amounts of the salts
hexadecyltrimethylammonium brom;de and sodium p~chloro-
S benzoate. The finished solutions also conta;ned the cor-
responding molar amount of NaBr. The results of the in-
vestigation of drag reduction in the turbulence rheometer
are summar;zed ;n Table 11.
Fxample 11
For an extended test, an aqueous solution was pre-
pared of hexadecyltrimethylammonium salicylate to have a
total content of 700 ppm from a 1:1 molar m;xture of hexa-
decyltrimethylammonium brom;de (CTA-Br) and sod;um sali-
cylate (Na-Sal) by we;gh;ng 92.~g of CTA-Br and 40.6g of
Na-Sal into 190 kg of water. The substances were dissol-
ved by stirring the coLd mixtures, and the solutions were
then conditioned at 60C for 5 hours and then stored at
23 for 6 days.
Drag-reducing act;v;ty ~as invest;gated ;n a flow
~0 apparatus (cf. for example, Ind. Eng. Chem~ Proc. Des;gn
Developm. 6,309 ~1967)) in wh;ch the solution is pumped
in a cycle through pipes. After an appropriately long
;nlet section, the pressure drop is measured over a section
which is 1 m long and has a cross-section of 1.4 cm. The
pump used was an adjustable screw pump from Netzsch,
namely the 2NE 80 model~
The said solution of CTA-Sal and NaBr was subjected
at room temperature in th;s flow apparatus to the follow-
ing Measurements, which were carr;ed out in succession
3~2~34Z~
~ 19 -
without a break in between
1) a flow curve measurement at 23C 1 hour after
the solut;on has been poured ;nto the apparatus;
2) an extended test over 7 days at a flow velocity
of 3.1 m~s, which corresponds to a Reynolds num-
ber of Re ~ 53,000;
3) a flow curve measurement ;mmediately on comple-
tion of the extended test;
4) an extended test over 16 hours at a Reynolds num-
ber of Re ~Remax, i.e. at a flow velocity of
5.5 m/s, wh;rh corresponds to Re = 90,noo;
5) a flow eurve measurement immed;ately on comple-
t;on of the extended test; and
6~ a flow curve measurement after 3 days at rest.
Table 12 summar;zes the results of the measure-
~ents 1-6.
Example 12.
By means of the method described in Example 11,
an aqueous CTA~Sal solution was prepared from CTA-Br and
Na-Sal to have a total CTA-Sal and NaBr content of 10,000
ppm ~ 1% by weight, and invest;gated in a disk apparatus
at 23C, 60C, 70C and 8UCA In the said disk
apparatus, a disk which has a diameter of 20 cm revolves
in the solution under test. Disk and solution are inside
25 a thermostated casing which has an internal diameter of
22cm, and the gap between ~he bottom plate and the top
plate amounts to 1~1 cm~ The tor~ue, M, of the disk is
measured as a ~unction of the number of revolutions per
minute, U.
~z~342~L
- 20 -
The two measured quant;ties can be used to calcu-
late the following dimensions as variables:
M
= drag coefficient = _ _ 2 5
1/2 ~ C~ R
Re = Reynolds number ~
M is the torque,L"I denotes the angular veloci~, t~e other
sylr~ls have the meamng as give3l oll page 11, The log-log plot of ~i~
a~ainst P~ then gives flaw curves as sh~ in Figur2 2 which can be ccan-
pared wit~ the flow curves for pipe flaw. ~he flaw curves for ~rdter in the
turb~lent regic~ is given ;~ 0 0995
by .ReO, 2
and is shown in Figure 2 as the solid straight l;ne. The
drag reduct;on, ~ , ;s calculated as for pipe flow. Figure
2 shows the flo~ curves for the said CTA-Sal solut;on for
the turbulent region at 23C, 60C, 70C and 80C.
As the figure shows, there is marked drag reduction ~ithin
the range 23C - 70C, and there is a small residual
effect even at 80C.
Example 13
8y means of the method described in Examples 1 and
4, an aqueous solution contaîning 750 ppm of CTA-Sal tl~78 x
1~ 3 mole~liter) and 1.78 x 10 3 mole of Na2C03 per
liter was made up, and subjected to an 11 day test in the
disk apparatus after the flo~ curve had been measured as
described in Example 1~.
The flo~ curve gave a max;mum drag reduction of
~ max = 36X at Remax ~ 1.09 x 10~ Nh;ch corresponds to
a number of revolutions of the disk per minu~e of U =
1D18 r.p.m~ The extended test ~as then carried out at
3~20~34;~
- 21 -
Re = 1.Q2 x 10b, which corresponds to 913 r.p.m. Table
13 conta;ns the values for the drag reduct;on ~ after
each day.
Examp(e 14
By means of the method descr;bed in Example 1,
solut;ons of hexadecyltrimethylammon;um thiocyanate (CTA-SCN)
were prepared with concentrations of 200, SOO, 750, 1000
and 2000 ppm, and measured at 45 and 55C in the tur-
bulence rheometer. Table 14 summarizes the results.
Example 15
By means of the method descr;bed ;n Examples 1,
3 and 4, aqueous solutions were made up to contain 750 ppm
in each case t2.19 x 10 3 mole/liter) of CTA-SCN and the
follow;ng NazCO3 concentrations (in mole/liter):
~ x 10 4, 2 x 10 4, 1 x 1C 3, 1.78 x 10 3 and
4 x 10-3.
In a second test, solut;ons which each contained
750 ppm of CTA-SCN were adjusted with NaOH to a pH 10.8
and w;th HCl to a pH 2.7.
Table 15 summar;zes the results of the ;nvestiga-
tion of drag reduction in the turbulence rheometer at45C.
Examp~e 16
By means of the method descr;bed in Example 4,
solutions were made up o-f hexadecylpyridin;um th;ocyanate
~5 conta;ning concentrations of 500 and 1000 ppm, and measured
at 45C in the turbulence rheometer. Both solutions
had a drag-reducing effect, namely at 500 ppm with Remax =
4400 by ~max = 53% and at 1000 ppm with Remax = 64CO
by ~max = 54X.
2(~34i~
.
- 22 -
Example 17
By means of the method described ;n Example 10,
aqueous solut;ons were made up to conta;n var;ous concen-
trations of n-aLkyltrimethylammonium thiocyanate ~CnTA-
SCN) by wei~hing out equimolar amounts of the saltsn-alkyltrimethylammonium chloride and sodium thiocyanate.
The f;n;shed solutions thus also conta;ned the correspon-
ding molar amounts of NaCl. The results of the invest;-
gat;on of drag reduction in the turbulence rheometer are
summar;zed in Table 16.
Example 18
By means of the method descr;bed in Examples 10
and 17~ aqueous solutions were made up of n-alkyltr;methyl-
ammonium p-toluenesulfonate ~CnTA-PTS) by weighing out
equimolar amounts of the salts CnTA Cl and sodium p-
toluenesulfonate. The results of the investigat;on of
drag reduction ;n the turbulence rheometer are summar;zed
in Table 17.
E_ ple 19
By means of the method descr;bed ;n Examples 10 and
17, aqueous solutions were made up of hexadecyltr;methyl-
ammon;um n-alkylcarboxylate (CTA-CxH2x+1COO) by weigh-
;ng out equimolar amounts of the salts CTA Cl and CxH~x~1Coo.
The results of the investigation of drag reduction in the
turbulence rheometer are summarized in Table 18.
2~
Table 1
CTA-Sal ~max
T ~C~ Concentration ~ppm~ Remax (% drag reduction)
22 130 5300 + 500 56 + 3
22 150 5400 ~ 500 57 + 3
22 200 5200 + 500 5~ + 3
22 300 4700 + 500 ~6 + 2
22 S00 5400 + 500 52 + 3
22 750 6700 + 700 53 + 3
22 1000 10500 + 100064 + 3
22 1500 12300 + 120064 + 3
22 2000 14400 ~ 140065 + 3
Table 2
CTA - Sal ~max
T LC~ Concentration [ppm~ Remax (~ drag reduction)
. . .
52 130 -
" 150
200 ~ no effect
" 300 _
" 50O 5100 + 500 59 + 3
" 750 8400 + 800 65 + 3
" 1000 10300 ~ 100066 + 4
" 1500 16600 + 160069 + 4
2000 18600 + 180068 + 4
84~
-- 24 --
Table 3
C e t y l p y r i d i n i u m s a l i c y ~ a t e
Tt C~Concentration ~ppm~ Remax ~max~
250
300 4500 + 500 54 ~ 3
500 5800 + 600 55 + 3
1000 7600 + 800 57 ~ 3
300
500 4200 + 400 54 + 3
1000 6500 + 70063 t 3
Table 4
. .
.~,easurement Te~erature 22C; CTA-Sa~ concentrat;on: 750 ppm
rP p ml, p H m a x m a x [
.
750 3.2 10900 + 1100 65 + 3
750 4. 2 9200 ~ 900 64 + 3
750 4.95 6600 + 700 ` 53 ~ 3
750 7. ~ 6400 + 600 59 + 3
750 ` 10 8100 ~ 800 61 + 3
75Q 1 n . 9 14600 + 1400 69 + 3
3L2~ Z~
- 25 -
Table 7
r leasurement Te~pera ture 22&; C T A - S a l c o n c e n t r a t; o n : 750 p p m
CaC l2 concent rat i on
mo l e / l i t e r ppm ma x
x 10 4 11 10800 + 1100 64 + 3
3 x 10 4 34 11800 + 1200 65 + 3
x 10 3 111 16200 + 1600 68 + 3
1.78 x 10 3 200 16700 + 1600 69 ~ 3
4 x 10 3 440 15300 + 1500 68 + 3
1 x 10 1110 16400 + 1600 68 ~ 3
x 10 111100 10600 + 1100 62 ~ 3
Table 8
.
reasurement Terperature æ c; CTA-Sal concentration: 750 ppm
Na2S04 concentration
mole/liter ppm max oc max [%~
x 10 4 14 16000 + 1600 67 _ 3
2 x 10 4 29 17800 ~ 1800 70 + 3
3 x 10 4 43 16900 _ 1700 70 + 3
x 10 3 140 18300 _ 1800 69 _ 3
1.78 x 10 250 18000 ~ 1800 69 + 3
4 x 10 3 570 18700 + 1900 69 3
x 10 1420 17300` + 1700 68 + 3
1 x 10 114200 13900 + 1400 60 ~ 3
.
~2~)8~2~
-- 26 --
TabLe 5
Measurement Ten~erature 22&; C T A - S a l c o n c e n t r a t i o n : 750 p p m
NaCl concentration
mole/l;terppm Remax ~max C%~
x 10 4 6 6000 600 55 + 3
5 x 10 429. 5 10200 + 1000 66 _ 3
x 10 358 . 5 11600 _ 1200 66 + 3
1.78 x 10 3100 13600 + 1400 68 _ 3
5 x 10 3290 16000 160068 3
x 10 2590 15900 + 160067 + 3
5 x 10 22900 14600 + 150067 _ 3
O .10 5800 13800 + 140067 + 3
0.35 20500 ~ Smal l residual drag-reducing
0.70 40900 effect of 10 -20X w-ithin the
1.00 585Q0 Reynolds number range from
4000 - 15000.
Table 6
NleasureTent Ten,perature ~2C; C T A - S a l c o n c e n t r a t i o n : 750 p p m
Na2C03 concent rat i on
mole/liter ppm pH Re . ~max [~
__ __ m a x
1 x 10 4 10.6 7.67100 _ 700 57 + 3
2 x 10 4 21.2 10.014300 + 1400 68 + 3
1.78 x 10 3189 10.616600 + 1700 68 + 3
6 x 10 3 636 11.0 15900 + 1600 66 + 3
2 x 10 2 2120 11.2 16500 + 1600 60 + 3
*)1 x 10 110600 11.1 13400 _ 1300 65 + 3
*)Solution already contains small amounts of
precipitate.
~013~2~1
-- 27 --
Table 9
Measurenænt Te~erature 22C; C r A - S a l c o n c e n t r a t i o n : 750 p p mMgHP04 concen t rat i on
mole/liter ppm R max ~ max [%~
8 x 10 5 14 14400 + 1400 68 + 3
x '10 417.5 14300 + 1400 66 ~ 3
2 x 10 4 35 15500 ~ 1600 68 ~ 3
3 x 10 4 52 16800 + 1700 68 + 3
6 x 10 4105 17200 + 1700 69 + 3
x 10 3175 16500 + 1600 69 + 3
*)1.78 x 10 33?0 16300 + 1600 68 + 3
*) The solution showed marked turbidity.
Table 10
I~leasurement T~Tperature 22 C; C T A - S a l c o n c e n t r a t i o n : 750 p p m
FE2(S04)3 concentration
mole/liter ppm pH Remax CmâxL%~
5 x 10 5 20 4.513500 + 1400 68 ~ 3
x 10 4 40 4.117700 + 1800 68 + 3
2 x 10 4 80 3.915900 + 1600 68 ~ 3
*~ 3 x 10 4 120 3.717400 ~ 1700 66 ~ 3
*) Small amount of precipitate present in the solwtion.
- 28 ~
Table 11
T~C~ Surfactant Con- Remax max t
centrat;on [ppm~
-
5000 31700 _ 3200 70 + 4
200U 15800 + 1600 68 + 3
Table 12
Measure- Remax C3cmax C%~ ~
ment
50000 + 2500 77 + 4
2 *) 53000 + 25no 61to 75 + 4
3 48000 + 2500 ~76 ~ ~t
4 *) 90000 no effect **)
S 47000 + 2500 76 ~ 4
6 49000 + 2500 76 + 4
*) Re numbers for the extended test.
**) Since this extended test ~as carr;ed out at
Re>Re , there was no drag reduction.
max
Table 13
Measurement Temperature 22C; CTA-Sal - - 1.78 mole/liter
+ Na2C3 - 1.78 mole/liter
Time(Days) Re a~ maxt7~3
0 1.02 x 106 33 + 2
1.02 x 106 32. _ 2
2 1.02 x 106 32 + 2
3 1.02 x 106 32 + 2
4 1.02 x 10~ 35 * 2
1.02 x 1o6 35 + 2
6 1.02 x 105 36 ~ 2
7 1.02 x 106 33 + 2
8 '1.02 x 106 - 33 + 2
11 1.02 x 106 32 + 2
.
~L2~
Table ?4
CTA-SCN
T~ C~ Concentration [ppm~ Remax Cmax ~%.¦
. . _ _ . . . _ . . _ _ .
200 4100 + 400 57 + 5
500 8500 + 900 57 + S
750 9300 + 900 57 + 5
1000 -12100 + 1200 60 + 6
2000 18800 + 1900 65 + 6
500 - -
750 6300 51 + 5
1000 9900 67 + 6
2000 20400 68 + 6
Table 15
. . .
Measurement Temperature 45C; CTA-SCN concentration: 750 ppm
Na2C03 con pH Re cC
centration max max
moleJliter
. _ _ . . _ _ . _ .
1 x 10 4 7~5 8700 + 90D 55 ~ 5
2 x 10 ~ 10.0 10700 ~ 1400 58 + 5
1 x 10 3 10.3 14600 + 2500 67 + 3
1~78 x 10 31 n . 6 9100 + 900 66 + 3
4 x 10 10.8 - -
. _ _ _ _ . _A
Addition of HCl 2.7 10000 + 1000 63 + 3
Addltion of NaOH 10.814400 + 1400 67 + 3
12~18~
- 30 -
Table 16
CnTA-SCN + NaCL
CnTA T[C~ tion ~ppm~ max Cmax ~%~
C18T~ 60 5005400 + 500 31 _ 3
C18TA 60 8006300 + 600 46 + 4
CZO/Z2TA 90 3006500 + 700 61 + 6
C20t22TA 90 30011100 _ 1000 64 + 6
,
CnTA represents ~CnH2n+1N(cH3)3~+
Table 17 `~ -
_
CnTA-PTS + NaCl
CnTA T[C~ Concentra- max GCmaxt ]
C16TA 22 5000 25800 + 2600 65 * 6
C16TA 40 4000 3300 + 400 35 + 3
C18TA 40 1000 3600 _ 400 41 + 4
Z0/22 60 1000 5000 + 500 28 + 3
C1~TA 4Q 3000 6800 + 700 28 + 3
~ TA represents ~CnH2n+1N(CH~)3~
1~0~ 2~
- 31 -
Table 1~
CTA ~xH2x+1C + NaCl
Cx~l2x~1C T~C~ Concentra- max ~max
. .
C7H15C00- 45 50003700 + 400 36 + 3
8 17 22 500040200 + 400073 + 7
8H17C 60 30003500 ~ 300 41 + 4
8 17 60 50004700 + 500 35 + 3
C9H19C00- 22 20ao22900 ~ 230070 + 7
10HZ1 C0O 40 200027100 ~ 240045 + 4
