Note: Descriptions are shown in the official language in which they were submitted.
IMPRO'lED METHOD FOR CRYSTALLIZING
ANH'!DROUS FRUCTOSE FROM ITS AQUEOUS SOLUTIONS
~.
INTRODUCTION
? FIELD OF THE INVED1TION
3 This invention relates to the production of
crystalline fructose. riiore specifically, it provides a method
for large scale, high capacity, high yield production of
cr~_rstalline fructose through the use of a crystallizes with
optimal heat and mass transfer properties.
BACKGROUND OF THE INVENTION
The present invention relates to an improved method
for crystallizing anhydrous fructose crystals from water
solution. Disclosed herein is an economic method for producing
=' large scale, high yields of crystalline fructose. Crystalline
'-3 fructose is generally obtained by seeding supersaturated
fructose solutions to induce crystall'_ne'growth. Due to the
solubility and stability characteristics of fructose and high
16 viscosity of fructose solutions, however, it is often
problematic to maintain the optimum conditions to insures the
13 economic production of a pure crystalline product.
~a
Fructose is very soluble in water and the solutions
1'0 : are extremely viscous. A large amount of heat due to high
'1 crystallization heat of fructose, mixing heat and additional
22 cooling of the mass must be removed. during fructose
'3 crystallization. In addition, because fructose has a very
narrow metastable zone, the temperature difference between the
'' solution and the cooling surface must be quite low thus making
'° the crystallisation very difficult.
?7
To overcome this difficulty, several prior art
processes involve the use of organic solvents to crystallize
fructose from aqueous solutions. In Finnish Patent Application
30 No. 862025, for example, a continuous fruc'~ose crystallization
LB148832288
~' ..
1 ~~ method using organic solvents is described. The viscosity of
i
the fructose sol.~tion, however, results in a lowering of
3 productivity, thus the yield is only about 40a and the
4 productivity about 0.17 t/m3/d even if the mass is pumped
through a vertical crystallizer. The productivity (t/m3/d) is
defined as the production rate of crystals (metric tons) per
7 the total volume of the crystallizer (cubic meter).
8 Crystallization from an organic solvent or water
solvent mixture is also described in Staley's European patent
015017. The use of organic solvents, however, creates
11 disadvantages with large scale crystallizations. These include
12 fire hazards as well as the fact that solvents are toxic and
13 therefore unsuitable because small residues remaining in the
14 crystalline product will leave it unsuitable for use in foods.
1' Several methods have been developed which avoid the
is use of organic solvents in the fructose crystallization
17 process, but these methods are often disadvantageous
18 economically because of the high viscosity and unstable nature
19 , of superstaturated fructose solutions. UK Patent Application
i 2172288A teaches a method for the continuous crystallization of
21 ' fructose from an aqueous solution. The syrup is rapidly mixed
22 with seed and put onto a surface until a cake is formed, which
23 is then conminuted to a free flowing granular product.
24 Although this method avoids the problem of continuous handling
2' of viscous solutions, the granular amorphous product contains
all of the impurities that were in the feed syrup. In
27 addition, the extra grinding and drying stages raise the
28 operation costs considerably. Similar costs are incurred using
29 the method described in U.S. Patent No. 4,199,373, wherein
syrup is seeded with crystalline fructose and allowed to stand
_z_
CA 02034475 2001-06-13
in a mold or container, after which the crystalline
material is recovered, dried, and ground.
Several patents describe processes wherein
fructose is allowed to selectively crystallize from an
S aqueous solution. In Japanese application 118,220,
corresponding to the Japane Patent publication 60-
118,200, published on June 25, 1985, two towers, one for
Braining and one for crystallization are described. Feed
from the first tower, containing 33-50% fructose syrup,
is mixed with massecuite (crystal-containing) overflow
from the second tower. The resultant mixture is cooled
as the product moves downward in laminar flow. The
crystalline fructose is then obtained by centrifugation.
Although this process avoids the additional drying and
grinding steps of other crystallization proceses, its
productivity is low and the scale up capacity is limited
because of the necessity for vertical laminar flow and
heat transfer demands.
One effective procedure for crystallization of
fructose from aqueous solutions is described in U.S.
3,928,062. The patent described a method wherein a
supersaturated solution is seeded and then evaporated
and/or cooled under moderate stirring while maintaining
the concentration and temperature within certain ranges.
By continuously concentrating the mother liquor, it can
be used to produce multiple crops of fructose crystals.
Although a suggestion is also made that cooling alone can
be used, such a procedure is not considered as
advantageous as those using continuous evaporation
because the mother liquid must be reconcentrated at the
start of each batch. Although such a procedure is useful
for producing small batches of crystalline fructose, such
a process could not be used in an industrial scale
production due to heat transfer constraints as well as
lack of adequate mixing and control of
-3-
1 j supersaturation.
According to U.S. 3,°33,305, large fructose ciystals
3 are obtained in a two stage batch method from avatar solution by
adjusting the pH of the solution and slowly cooling the mass to
create a supersaturated solution which, when seeded, is optimal
for crystal formation. Because of the long crystallization
time of the process, a pH adjustment must be done and the
productivity of the method is only about 0.25 t/m3/d.
Although all of the above processes have been used
successfully for the production of crystalline fructose, it has
11 heretofore been thought to be impossible to produce crystalline
12 fructose on a large scale with high yields, high capacity
13 (productivity) and good urit from ita a
p y queous solutions
1~ without resorting to costly processing steps including
evaporating, drying, and grinding. An object of the present
'-° invention is to provide a cost effective method for large
scale, high capacity production of fructose crystals in high
18 yields.
19 Another object of the invention is to provide a
method for crystallization of fructose which does not require
21 the use of organic solvents and without the need of pH
22 adjustment.
23
Still another object of the invention is to provide a
24 crystallizing apparatus that has optimal heat transfer and
2' mixing capacities for large scale production of high purity
26 fructose crystals.
Further objects will be evident from the description
28 of the invention which follows.
29 '
SUrL~SA.RY OF THE INVENTION
Disclosed herein is a method for producing
-4-
I I
1 ~ crystalline anhydrous fructose whereby a small amount of
crystalline fructose, providing a nucleation site, is added to
3 a fructose solution or crystalline seeds are allowed to form
spontaneously in the solution. In a multistage crystallization
process, all, stages except the first are seeded with a crystal
foot, which is a mass of crystals and mother liquid
(massecuite) from a previous crystallization. The resulting
mixture is mixed while cooling slowly to carefully maintain the
temperature and degree of saturation for anhydrous
crystallization. ,
11 Tn the production of fructose crystals, low
1z supersaturation and a small differential should be maintained.
13 In a preferred embodiment, the temperature differential between
14 the solution and the means used for cooling the solution is
less than about 6°c, and the fructose solution, although
1° supersaturated, has a supersaturation of no more than 1.25,
preferably between 1.1 and 1.2. Such conditions can most
18 readily be controlled in a heat transfer apparatus or
19 1 crystallizes whereby a heat transfer surface of at least
5/m2/m3 is provided. When such a crystallizes is used, it is
21 not inclined more than 45 degrees, and it contains means for
22 effective mixing, as well as cooling plates optimally spaced
23 not more than 300 mm apart and having an open sector in the
24 cooling plates of at least 5 degrees along the crystallizes.
2S In this embodiment, the mixer blades are located in
'6 between and not more than 30 mm from the cooling surfaces.
Preferably, the velocity of the mixer blades is at least about
28 50 mm/sec during the crystallization process.
29
BRIEF DES CRTPTTON OF TFiE DRAWIDiGS
Fig, 1 is a side view, partially in cross section, of
_5_
1 ~ a fructose crystallizing apparatus according to the present
I
invention.
3 Fig. 1A is a right side elevated view, partially in
cross section, of a crystallizing apparatus.
Fig. 13 is an enlarged partial section view of the
crystallizer shown in Fig, 1A.
Fig. 2 is a side view, partially in cross section,
of another embodiment of the invention.
DETAILED DESCRIPTT_OPI OF THE INVENTION
A. Process in General i
11 According to the present invention it has now been
12 found that it is possible to improve.fructose crystallization '
13 from water solution by a method where a horizontal cylindrical
1~ crystallizer is used both to allow efficient heat transfer
1~ within a small temperature differential and to effectuate good
1° mitring of the mass. Although it is not intended to be a
1~ limitation to the invention, it is believed that the parameters
18 described herein are adapted to create a dynamic equilibrium
19 between crystalline anhydrous fructose and dissolved fructose
such that the growth of the crystalline structure is
21 sufficiently slow to avoid entrapment of water molecules.
22 The crystallization is carried out by seeding a
23 saturated or supersaturated fructose solution with a proper
"'~ amount of seed crystals or allowing the solution to form seeds
spontaneously, and then cooling the massecuite according to a
26 gradient which is determined during the crystallization. In a
2~ multistage crystallization rocess the f ..
p stages rom second ~.o
28 final crystallization are seeded with the proper amount of
29 crystalline foot. The proper amount of seeding crystals (Ms)
depends on their size (ds), their length (m), on the quantity
-6-
i ~:_:.
.. ~~Q~'~~~~~
;.
' i of the finished cr,rstals (M), and the desired crystal size (D)
as follows:
3 Ms (tons) _ (ds/D)3 x M (tons)
The fructose mass is simultaneously mixed to ensure
optimum heat transfer and maximum crystal growth rate within
the mass. The crystallizing process is a batch process, but it
can be made semi-continuous by interconnection of several
similar crystallizers. A two-stage method is advantageous if
large crystal size of the product is preferable. The cooling
l0 program depends on the quality of the feed syrup, but the
11 productivity is typically 0.5-0.8 t/m3/d and cooling time is
12 typically 15-30 hours by this improved method.
13 , A crystal yield of 65a of dry substance can be
14 reached in the end of the crystallization. The recovery and
1' drying of the crystals are made by conventional methods. If
to the yield is very high, air bubbles can be mixed, at no more
than 200, into the mass before the crystals are separated from
18 the mother liquor to reduce the viscosity. This makes the
1° centrifuging easier. The size of the product is typically
20 , 0.4-0.6 mm and the purity is over 99.5%.
21 B. Crystallizes
2 It is through the use of a crystallizes that the
23 conditions of supersaturation and optimal cooling, mixing, and
24 mass transfer can be accomplished in a large scale manner. For
25 large scale production of fructose, the crystallizes is
2° optimally about 30 m3 in size.
2~ With reference to the drawings, there are shown
28 crystallizers that are horizontal or inclined typically 5
29 degrees, but not more than 45 degrees, to ensure effective
30 axial mixing and drainage of the system. In a crystallizes,
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CA 02034475 2001-06-13
the heat transfer surface must be at least 5 mz/m3, preferably more
than 10 mz/m3, so that the temperature difference between the
fructose mass and cooling plates is not more than about 6.0°C, even
if the cooling rate is 4°C/h.
With reference to Figures l, 1A and 1B, which depict an
embodiement wherein multiple crystallizing zones are present,
effective heat transfer is obtained when cooling water enters a
cooling jacket 3 through an inlet 8 and circulates through cooling
plates 2 which are situated inside the crystallizes and spaced not
more than 300 apart. The cooling water passes through the cooling
plates and out an outlet 9 located on the opposite end of the
crystallizes from the water inlet.
A motor 6 mounted on a supporting stand 7 drives a shaft
4 which, at its pont of entrance into the crystallizing apparatus
is surrounded by a sealing material 5. Strong mixer blades 1
extend from the shaft within the crystallizing apparatus. The
crystallizes comprises mixer blades and cooling elements, which
are situated inside the crystallizes. The mixer blades are
situated between the cooling elements such that the distance
between the blades and the cooling elements is not more than 30
mm. The mixing blades are situated between the cooling plates 2
so that the distance between the blades and the cooling plates is
not more than 30 mm to ensure proper mixing of the mother liquid
near the crystal surfaces. The rotation speed of the mixer is
such that the velocity of the top of the mixer blades is typically
130 mm/sec but not less than 50 mm/sec at any moment of the
crystallization. Small mixing efficiency was found to be
insufficient to keep the crystal growth rate high while too much
mixing resulted in spontaneous crystal forn~ation if
supersaturation is high.
Fructose syrup to be crystallized (mother liquid) enters
the crystallizes through inlet port 10. A horizontal flow in the
crystallizes is effected by a small open sector in the cooling
plates at least 5 degrees along the crystallizes.
_g_
CA 02034475 2000-04-13
1 Massecuite containing solution is removed from the
2 crystallizing apparatus through outlet 11 whereupon it is
3 centrifuged to collect the crystalline material.
4 Referring to Figure 2, in another embodiment of
5 the invention, the crystallizing apparatus may contain
6 only two crystallizing zones. Such a crystallizes
7 employs the same general components of the crystallizes
8 shown in Figure 1, but effective heat transfer is
9 accomplished through circulation of cooling water through
10 a cooling water jacket 3' and into a single cooling plate
11 2' which extends upward through the center of the
12 apparatus. Similarly, only two mixing blades 1' are
13 necessary for mixing of the crystallizing mixture. The
14 motor 5' and shaft 4' are similar to the same components
15 in Figure 1.
16 C. The Crystallization Process
17 The temperature difference between the fructose
18 mass and cooling elements is kept less than about 6.0° C,
19 and the supersaturation is kept less than 1.25,
20 preferably between 1.1 and 1.2, during the whole
21 crystallization process. The sufficient heat transfer
22 area and mixing efficiency keeps the temperature
23 difference between the fructose mass and cooling plates
24 small enough despite very short crystallization times.
25 The supersaturation which determines the cooling rate is
26 calculated during the crystallization as follows:
27 Y - 10000 x (Ct-Cml)
28 Ct x (100-Cml)
29
3 0 Qml - 10 0 X F - Y
31 100 - Y
32 Cml - F (Qml, Tm)
33
34 S - Cml x (100 - Cml')
35 Cml' x (100 - Cml)
36
37 Y - crystal yield, % of dry substance amount
38 Ct - total dry substance concentration, % w/w
39 Cml - measured mother liquid concentration, % w/w
_g_
i
2~~~t~~~
1 ~ Qml = mother liquid purity, ~ w/;o cf dry substance '
Cml' = saturation concentration of to mother liquid, ~ w/w
F = experimentally measured solubility function
Tm = temperature of the mass, °C
S = supersaturation
The mother liquid concentration and temperature are
measured by, for example, an on-line refractometer and a
6 suitable thermometer. The total dry substance concentration of
the mass and the purity of the feed licuid are obtained from
8 laboratory analyses. The solubility cf fructose in water is a
function of purity and temperature and is obtained
experimentally.
11 The aqueous feed solution contains glucose as a'major
12 impurity, and it contains not less than 90~ by weight fructose
13 relative to the total weight of dry solids. The dry solids
1~ concentration of the mass must be hi her ~ ~-
g than 90 w/w~ to ge~ a
reasonable yield if the final temperature of cooling is about
16 25°C. The pH adjustment of the feed syrup is not necessary
because of short crystallization times but the optimum pH range
18 of the feed syrup is 4.5-5.5 to minimize the degradation of.
19 fructose.
The careful supersaturation control., combined with
21 efficient heat transfer and effective mixing, results in
'' maximal cr stal +
y growth rates wi,.hout spontaneous crystal
23 formation during the entire crystallization process. The
productivity of 0.5-0.8 t/m3/d achieved in the main
crystallizaticn by this improved method is substantially higher
26 than the yield obtained using the most advantageous method
presented in the prior art.
28 In the preferred embodiment, the fructose solution is
z9 placed in the crystallizer after being evaporated to a
concentration of greater than about 90~ (w/w) dry solids and
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CA 02034475 2001-06-13
1 adjusted to ~he saeding temperature. During this
pre_
2 crystallization phase, the seeding is mace ar.d tie cooling
3 program is determined as set forth above. Fellcwing this
stage, a porticn of the mass is withdrawn, leavi.~.g a
crystalline "fcot" which series as the seed in tae following
main crystallization. Additional, concentrated feed is added
and t::e cooli.~.g program continued once again as set out above.
After the main crystallization the crystals are separated from
the ether li~sid by centrifugation and then dries.
In ar~cther embodiment, the crystal fect is used in
11 anoth~= crystallizes which is filled wit: additicnal syrup.
12 EXAIZPLES 1 -5
Crystallization F~rame'-~rs
'- " '' r.
'' BOLT. t a pre- and main cr:stallization experi__~.,ents
1~ were done wi_: the 6 liter pilot crystallizes s:.cwn in F~c. ..
16 ecruipped with cooling water jacket and erfective mixer. The
1' crystallizes was connected with a prograa.:,able t :ermostat MQ-.~
Lauda RKP* 20. The length of the crystallizes was 18 c:~ and't:Ze
diameter was 21-cm. The crystallizes has 42 m2/-~3 heat
20 transfer area, and it was slightly inclined.
21 The crystallizes consists of two crystallization
22 zones, the width of which were 8 cm, and two mixing blades were
'3 installed in Seth zones. The distance be_-aeen the mixer blades
2'' and cooling plates was about 1.5 c:~. The rotation, speed
o~ the
mixer was 11 rpm and the velocity of the tzp of mister blades
2' was 130 ~nm; se= during the e:ca:~ples.
27
:~e feed s::rup was obtained fro::. an industrial plant
28 and =t COns~s=~~ Of ~~.5a fr'.lCtOS2, 1.0; deXtrOSe, 2.2°S
29 oligosacchar_des and the rest being zainiy salts as analyzed by
gPLC. This s.~ru which had ocr '
p~ p c_-ystall~zing properties, was
*Trade-mark _11_
..
e~ ~ ~ ~~
1 chosen to demonstrate the effectiveness of the present '
invention. The pH of the feed syrup was 4.1, and it was
3 ~ adjusted to about 5.0 in all examples except No. 4.
'I The seed crystals were made from commercial fructose
crystals by grinding with Fritsh pulverisette type 14.702. The
6 mean particle size of the seed crystals was about 0.03 mm and
7 900 of the crystals were between 0.02-0.08 mm as analyzed by a
8 PP!T-PAMAS particle measuring and analyzing system. The
crystallization parameters of the examples are set forth in
Table 1 and the results are listed in Table 2.
11
12 Table 1. '
13 The Crystallization Parameters
14 Ex. 1 E:c. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
1~ pre main pre main pre main pre main pre main pre main
a 91.0 92.6 90.9 92 0 91.3 93 3 V 91.3 91.8 90.9 92 4 ~ 91 0.92.2
16 b 8.1 8.2 8.1 7.9 8.2 8.6 8.1 8.4 7.9 7.3 8.2 8.8
c .014 17.7 .038 14.2 .038 9.7 .038 10.8 .036 15.5 .038 10.3
17 d 56.5 57.0 56.0 57.0 57.0 57.0 56.0 56.5 ~ 56.0 57.0 56.0 57,0
a 35,5 28.0 36.0 28.0 40.0 28.0 37.0 24.5 35.0 28.0 37.0 25.0
18 g 24 21 26 24 24 15 24 20 72 24 24 30
19 = 5.0 5.1 5.0 4.1 5.0 4.9
21 a concentration of the mass, % w/w
b amount of the mass, kg
22
c amount of the seed crystals or crystal foot, % w/w
23
~4 of dry substance
d initial temperature of the crystallization, °C
26 a final temperature of the crystallization, °C
27 f crystallization time, h
2$ g pH of. the feed syrup
39
~ In Example 1, the fructose solution was first
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CA 02034475 2001-06-13
l adjusted to pH 5.0 with 5~ w~'a NaHC03 solution. The f=_ed svru~
was evaporated to 91.0o w/w and 8.1 kg cf it was transfers=d to
3 the crystallizes which temperature was 56.5°C. When the
4 crystallize= ;aas fir ed, the syrup was seeded with 0.014, seeds
and the cooling prcgsam of the pre-crystallization- Was started.
6 The concentration of the mother liquid was measured with a
laboratory refractometer, and the mass Was cooled to 35.5°C so
a that the calculated supersaturaticn maintained was less than
i.25. The du=anon of the c~ystallization was 24 h, and the
yield was 44.3% in the end of the crystallization.
11 when the pre-crystallization was finished, a part e?
12 the mass was pulled c=f and the rest was left in the
13 crystallizes se that the csystai feet, which determines the
crystal size of the product, in the beginning of the main.
v5 CryStdl llZat'_O.~. Wa5 17. % o. Tile CyllSta1112er Was filled Wlth
15 eVapora~ed fe°_.~. Syrup WhlCh WaS miXed With the Crystal fOOt SC
that the temperature gradually rose to 57°C and the drv
18 substance concentration rose to 92.6%. The cooling proc~am was
1° started when the crystallizes was f'_lled. The mass was coclad
20 to 28°C so that the suaersaturation was r"aintained at less t:~an
21 1.25. The du=ation of the main crystallization was 21 h.
22 . After the main crystallization, the crystals were
23 separated from the mother liquid and washed by a laboratory
24 centrifugal Hettich Roto Silenta* 2. The diameter of the
2~ cents if~~ca 1 baske t was 21 cm and t::e amoun t of the washi.~,a
'° water was 1.5-2.5o c~ the weight of h
the mass. T.e crystals
2~ were dr_ed by a laboratory fluidizaticn d=-res.
2a
The crysta'_ yield was 56.6% in the end of the
23
csystali~zatior., and the purity of the cs=stair was 990 of the
30 dsv substance. The mean size of the product was 0.49 m.'n and
*Trade-mark
-13-
~~z~~-~~'~~
' ~ the standard deviation from the mean size was 47% as measured
2 by a sieve analysis.
3 The crystallization procedures as set forth in the
4 remaining examples all had the same operation stages of EY.~,MPi:E
1. The variables were measured during the experiments as
6 described in Tables 2 to 7. The time from the beginning of the
cocling in the main crystallization, the cooling water
8 temperature, the concentration and supersaturation of the
i
mother liquid are listed. In each case, the concentration was
measured by a laboratory refractometer. The temperature
11 difference between the cooling water and the mass was less than i
12 1.0'C.
13
Examale 1
14 Table 2. Variables in Test Run T1
pre cryst. main cryst.
16 Time Temp Conc s Time Temp Conc s
7 h °C w/w % - h °C w/w
0.0 56.5 91.0 1.16 0.0 57.0 91.2 1.15
18 12.9 52.2 90.5 1.23 0.5 57.0 91.1 1.15
14.1 51.1 90.2 1.23 11.3 50.5 88.5 1.03
l~ ' 15.6 49.7 89.6 1.20 12.5 50.0 88.3 1.02
16.6 48.8 89.4 1.20 14.3 46.9 88.1 1.08
17.5 48.0 89.2 1.20 15.9 44.3 87.7 1.11
18.5 47.0 88.7 1.16 23.0 28.0 84.5 1.13
21. ' 20.3 42.9 88.3 1.23
24.9 35.5 84.9 1.05
22
23
24
26
27
28
29
-14-
?~~-~~~t~'~
1 .I
::~:atole
2
,. 3. in
Table Variables Test
Run
~2
3
4 pre ca~'sW maincryst.
Ti
me emp Conc s Time TempConc s
h C w/w - h C w/w % -
'-
0.0 56.0 90.9 1.17 0.0 57.090.8 1
11
0.5 56.0 90.9 1.17 0.5 57.090.4 .
1
06
4.1 54.0 90.9 1,24 1.6 56.290.3 .
1
07
10.7 54.1 90.2 1.14 2.5 55,590.0 .
1
05
22.0 42.9 87.7 1.16 (42.7 28.083.2 .
8 1.02)
23.5 39.8 87.0 1.15
24.5 37.8 86.4 1.14
26.0 36.0 85.6 1.10
26.8 36.0 85 1
2 07
t0
.
al
12
Example
3
13 Table 4. in Run n3
Variables Test
1.
Y
pre maincryst.
15 Ti cryst.
me Temp Conc s Time TampConc s
15
h C w/w - h C w/w
%
0.0 57.0 91.3 1.21 11.2 41.087.2 1
1' 12
3.6 56.5 91.1 1.18 12.5 37.086.0 .
1
09
18.0 49.3 88.9 1.12 13,0 35.485 .
18 7 1
09
19.2 48.0 88.9 1.15 14.6 30 . .
7 84
8
. . 1.10
19 20.1 46.9 88.5 1.14 15 28
5 2
. . 84.5 1.13
21.4 44.7 87.6 1.10
22.7 42.3 86.9 1.08
20
24.1 39.9 86.5 1.10
21
22
23
24
26
27
28
29
30
_15-
~i
I
I
1 i
~tam le '
4
2 Table 5. Variablesin Test n4
Run
3 '
pre crys;.- main cryst.
4 Time Temp Conc s Time Temp Conc s
h C w/w o - h C w/w -
o
0.0 56,0 91.3 1.23 14.6 39.6 86 1
8 13
6 0.5 56.3 91.0 1.17 15.5 37.7 . .
86.2 1.12
3.2 55.8 90.0 1.19 16.5 35.5 85.7 1
12
7 20.5 45.1 87.4 1.07 17.5 32.8 85.2 .
1.12
21.9 42.4 86,9 1.01 18.5 29.9 85 1
1 18
8 23.2 39.7 86.6 1.11 19.5 27.0 . .
84.5 1.17 i
24.5 37.2 85.7 1.09 20.0 24.5 83 1
8 16
. .
I
i
i
11
Example
5 i
2
Table 6. Variablesin Test ~5
Run
13
14
pre cryst main cryst.
Time Temp Conc s Time Temp Conc s
h C w/w ~ - h 'C w/w
16 0.0 56.0 90.9 1.17 0.0 57.0 91.1 1.15
5.5 55.5 90.9 1.18 1.3 56.2 90.5 1.09
17
70.6 36.1 85.3 1.07 16.8 43.0 87.3 1.09
18 19.0 39.5 86.5 1.09
21.9 33.3 85.1 1.09
19
24.0 28.9 84.4 1.11
21
22
23
24
26
27
28
29
_1 6,
_ ~ ~
n
0
Example
1 Table 6
3 7.
Variables
in
Test
Run
#6
pre ryst main cryst.
c
4 Time Temp Conc s Time Temp Concs
h 'C w/w ~ - h C w/w
%
-
0.0 56.0 91.0 1.18 0.0 57.0 90 1
5 07
6 0.8 55.9 90.8 1.17 14.5 39.8 . .
87.01.14
l00~.8 47.1 87,9 1.07 15.4 38.0 86.01.08
22.1 4i.9 86.8 1.09 16.4 35.6 85.41.08
22.S 40.5 86.4 1.08 18.1 30.7 84 1
6 10
8 23.9 38.2 85.9 1.08 18.8 28.9 . .
84.31.11
24.5 37.0 85.7 1.09 20.0 25.3 83 1
7 12
9 . .
l0
11 Table 8.
Results
of
Test
Runs
in
Examples
1-6
12 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
13 nre main pre main pre main pre main
pre mainpre main
a 44.3 56.6 40.5 57.5 38.8 62.8 42.6 58.840.9 57.8
4 54.5 41.9
'' b - - 60.6 56.2 58.?57.1
c 0.17 0.49 0.16 0.62 0.16 0.66 0.13 0.620.13 0.37
0.35 0.19
d 47 31 27 59 38 57
a 99 99.5 99.9 - 99.9
16 F
0.52 0,75 0.46 0.70 0.48 0.90 0.52 0.670.50 0.78
0.71 0.17
17
18 a crystal yield in the end
of the pre
19 crystallization and before gingin the
centrifu
main crystallization, % w/w
'1 b crystal yield of the product,
% w/w
2
c mean size of the product,
mm
23 d standard deviation from the ze the
mean si of
24
product, %
2S a purity of the product, % substance
w/w of dry
26 f
productivity, t/m3/day
'7
The mean size and the standard the
deviation of
28
pro duct were measured by the and in
sieve analysis
29
the end of the pre-crystallization
by a laboratory
mic roscope.
-17-
