U.S. patent application number 12/149794 was filed with the patent office on 2008-11-13 for method and apparatus for producing salt water-mixed sherbet ice.
This patent application is currently assigned to Mitsubishi Electric Corporation. Invention is credited to Hiroyuki Hamashita, Shinichi Hattori, Hiroshi Yamamoto.
Application Number | 20080276629 12/149794 |
Document ID | / |
Family ID | 39942298 |
Filed Date | 2008-11-13 |
United States Patent
Application |
20080276629 |
Kind Code |
A1 |
Yamamoto; Hiroshi ; et
al. |
November 13, 2008 |
Method and apparatus for producing salt water-mixed sherbet ice
Abstract
Salt water fed to an ice-maker 1 is cooled to generate ice. The
ice is scraped by scrapers 1c to form small particles of ice which
are mixed with the salt water to generate salt water-mixed sherbet
ice 143. The salt water-mixed sherbet ice is fed from the ice-maker
to an ice storage tank 14 so as to be stored in the ice storage
tank. A predetermined amount of the salt water-mixed sherbet ice
with a predetermined sherbet concentration at a predetermined low
temperature is stored in the ice storage tank while the salt
water-mixed sherbet ice is refluxed from the ice storage tank to
the ice-maker. Water 24 is injected into the salt water-mixed
sherbet ice in the process of producing the salt water-mixed
sherbet ice. By the method of producing salt water-mixed sherbet
ice, salt water-mixed sherbet ice at a relatively high temperature
can be produced easily.
Inventors: |
Yamamoto; Hiroshi; (Tokyo,
JP) ; Hamashita; Hiroyuki; (Tokyo, JP) ;
Hattori; Shinichi; (Tokyo, JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
Mitsubishi Electric
Corporation
Chiyoda-ku
JP
|
Family ID: |
39942298 |
Appl. No.: |
12/149794 |
Filed: |
May 8, 2008 |
Current U.S.
Class: |
62/71 ; 62/458;
62/459; 62/498 |
Current CPC
Class: |
F25C 1/145 20130101;
F25C 2301/002 20130101 |
Class at
Publication: |
62/71 ; 62/458;
62/459; 62/498 |
International
Class: |
F25C 1/14 20060101
F25C001/14; F25D 3/02 20060101 F25D003/02; F25B 1/00 20060101
F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 11, 2007 |
JP |
JP2007-126908 |
Claims
1. A method of producing salt water-mixed sherbet ice, comprising
the steps of: generating salt water-mixed sherbet ice by cooling
salt water fed to an ice-maker to generate ice, scraping the ice by
scrapers to form small particles of ice to thereby mix the small
particles of ice with the salt water; feeding the salt water-mixed
sherbet ice from the ice-maker into an ice storage tank to thereby
store the salt water-mixed sherbet ice in the ice storage tank; and
storing a predetermined amount of the salt water-mixed sherbet ice
with a predetermined sherbet concentration at a predetermined low
temperature in the ice storage tank while the salt water-mixed
sherbet ice stored in the ice storage tank is refluxed from the ice
storage tank to the ice-maker repeatedly a plurality of times;
wherein water is injected into the salt water-mixed sherbet ice in
the process of producing salt water-mixed sherbet ice.
2. A method of producing salt water-mixed sherbet ice according to
claim 1, wherein the injection of water is performed in the ice
storage tank.
3. A method of producing salt water-mixed sherbet ice according to
claim 2, wherein the injection of water is performed while the salt
water-mixed sherbet ice in the ice storage tank is stirred.
4. A method of producing salt water-mixed sherbet ice according to
claim 1, wherein the formation of small particles of ice by the
scrapers is stopped while the injection of water is performed.
5. A method of producing salt water-mixed sherbet ice according to
claim 3, wherein the formation of small particles of ice by the
scrapers is stopped while the injection of water is performed.
6. A method of producing salt water-mixed sherbet ice according to
claim 1, wherein the formation of small particles of ice by the
scrapers and the injection of water are performed alternately and
repeatedly a plurality of times.
7. A method of producing salt water-mixed sherbet ice according to
claim 5, wherein the formation of small particles of ice by the
scrapers and the injection of water are performed alternately and
repeatedly a plurality of times.
8. A method of producing salt water-mixed sherbet ice according to
claim 1, wherein water is removed from the salt water-mixed sherbet
ice before the injection of water.
9. A method of producing salt water-mixed sherbet ice according to
claim 7, wherein water is removed from the salt water-mixed sherbet
ice before the injection of water.
10. An apparatus of producing salt water-mixed sherbet ice,
comprising: an ice-maker which generates salt water-mixed sherbet
ice under control based on a controller in such a manner that ice
generated by cooling salt water fed to the ice-maker is scraped by
scrapers to form small particles of ice to thereby mix the small
particles of ice with the salt water; an ice storage tank which
stores the salt water-mixed sherbet ice fed from the ice-maker
under control based on the controller; and a water injecting unit
which injects water into the salt water-mixed sherbet ice; wherein
control is performed by the controller so that the salt water-mixed
sherbet ice stored in the ice storage tank is refluxed from the ice
storage tank to the ice-maker and the injection of water is
performed by the water injecting unit in steps of feeding the salt
water-mixed sherbet ice from the ice-maker to the ice storage tank
and refluxing the salt water-mixed sherbet ice from the ice storage
tank to the ice-maker.
11. An apparatus of producing salt water-mixed sherbet ice
according to claim 10, wherein the injection of water is performed
in the ice storage tank.
12. An apparatus of producing salt water-mixed sherbet ice
according to claim 11, further comprising a stirrer which stirs the
salt water-mixed sherbet ice in the ice storage tank under control
based on the controller, wherein the injection of water is
performed while the salt water-mixed sherbet ice in the ice storage
tank is stirred by the stirrer.
13. An apparatus of producing salt water-mixed sherbet ice
according to claim 10, wherein the formation of small particles of
ice by the scrapers is stopped during the injection of water under
control based on the controller.
14. An apparatus of producing salt water-mixed sherbet ice
according to claim 12, wherein the formation of small particles of
ice by the scrapers is stopped during the injection of water under
control based on the controller.
15. An apparatus of producing salt water-mixed sherbet ice
according to claim 10, wherein the formation of small particles of
ice by the scrapers and the injection of water are performed
alternately and repeatedly a plurality of times under control based
on the controller.
16. An apparatus of producing salt water-mixed sherbet ice
according to claim 14, wherein the formation of small particles of
ice by the scrapers and the injection of water are performed
alternately and repeatedly a plurality of times under control based
on the controller.
17. An apparatus of producing salt water-mixed sherbet ice
according to claim 10, further comprising a dewatering unit which
removes water from the salt water-mixed sherbet ice, wherein the
removal of water from the salt water-mixed sherbet ice is performed
before the injection of water under control based on the
controller.
18. An apparatus of producing salt water-mixed sherbet ice
according to claim 15, further comprising a dewatering unit which
removes water from the salt water-mixed sherbet ice, wherein the
removal of water from the salt water-mixed sherbet ice is performed
before the injection of water under control based on the
controller.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and apparatus for
producing salt water-mixed sherbet ice, in which ice generated by
cooling so-called salt water such as sea water supplied is scraped
as small particles of ice by a scraper to thereby produce salt
water-mixed sherbet ice having the small particles of ice mixed
with the salt water.
[0003] 2. Description of the Background Art
[0004] Sea fishes were heretofore generally cooled with blocks of
ice to keep freshness of the sea fishes. However, the sea fishes
might be damaged by the blocks of ice because of vibration during
marine and land transportation when the blocks of ice were ordinary
blocks of ice or the freshness of the sea fishes might be lost by
water generated by melting the blocks of ice. Therefore, in recent
years, a method in which ice generated by cooling salt water is
formed into sherbet-shaped or power snow-shaped ice mixed with salt
water (hereinafter referred to as salt water-mixed sherbet ice) by
a scraper (also called scraping machine or scraping blade) so that
sea fishes are cooled with the salt water-mixed sherbet ice, has
been used as disclosed in Patent Document 1.
[0005] It has been recently found that the temperature of salt
water-mixed sherbet ice for keeping the freshness and taste of sea
fishes varies according to the kind of fish when the sea fishes are
cooled with the salt water-mixed sherbet ice. For example, when sea
fishes are cooled with salt water-mixed sherbet ice at -3.degree.
C., there is a possibility that a bad influence such as freezing of
fish meat or clouding of fish eyes may occur according to the kind
and size of fish.
[0006] For example, when salt water-mixed sherbet ice with an ice
concentration (percent by weight of small particles of ice to the
salt water-mixed sherbet ice, also called ice packing factor (IPF))
of 30% is produced from general sea water (with a salt
concentration of about 3.5%), the temperature of the salt
water-mixed sherbet ice is -3.1.degree. C. When the salt
water-mixed sherbet ice at this temperature is used for cooling
fishes, fish meat of almost fishes is however frozen so that the
commercial value thereof is lost. It is therefore necessary to
adjust the salt concentration in order to provide salt water-mixed
sherbet ice at such a temperature that fish meat is not frozen. For
example, it is necessary to prepare salt water at a salt
concentration of 1.7% in order to produce salt water-mixed sherbet
ice with an ice concentration of 30% at -1.5.degree. C. (Refer to
Patent Document 1 for the relation between the salt concentration
and the temperature of salt water-mixed sherbet ice, though there
is no description about the relation between the ice concentration
and the temperature of salt water-mixed sherbet ice.)
[0007] When salt water with a low salt concentration, for example,
a salt concentration of about 1.5% is used, ice produced by an
ice-maker becomes so hard that there arises a problem that a
scraper of the ice-maker is worn severely and motive power for
driving the scraper becomes very large. Therefore, an attempt to
use ocean deep water (sea water 200 m or more below sea level) for
performing supercooling and canceling of supercooling has been made
(see Patent Document 2).
[0008] [Patent Document 1] JP-A-2002-115945 (FIG. 1 and paragraph
number 0035)
[0009] [Patent Document 2] JP-A-2006-10129 (FIGS. 1 to 3 and
description thereof)
[0010] If sea water with a low salt concentration (e.g. of 1.5%) is
used for producing salt water-mixed sherbet ice at a relatively
high temperature (e.g. of -1.5.degree. C.) as in Patent Document 1,
there arises a problem that the scraper of the ice-maker is worn
severely and motive power for driving the scraper becomes very
large. It is therefore preferable that salt water-mixed sherbet ice
at a relatively high temperature (e.g. of -1.5.degree. C.) can be
produced without use of sea water having a low salt
concentration.
[0011] Although Patent Document 2 has described that ocean deep
water (sea water 200 m or more below sea level) is used for
performing supercooling and canceling of supercooling, it is
difficult to produce salt water-mixed sherbet ice stably by such a
method for performing supercooling and canceling of supercooling.
It is therefore preferable that salt water-mixed sherbet ice at a
relatively high temperature (e.g. of -1.5.degree. C.) can be
produced without use of such a method and with use of unexceptional
sea water or easily available salt water.
SUMMARY OF THE INVENTION
[0012] In consideration of the aforementioned circumstances, an
object of the present invention is to provide a method and
apparatus for producing salt water-mixed sherbet ice at a
relatively high temperature (e.g. of -1.5.degree. C.) easily.
[0013] The present invention provides a method of producing salt
water-mixed sherbet ice, including the steps of: generating salt
water-mixed sherbet ice by cooling salt water fed to an ice-maker
to generate ice, scraping the ice by scrapers to form small
particles of ice to thereby mix the small particles of ice with the
salt water; feeding the salt water-mixed sherbet ice from the
ice-maker into an ice storage tank to thereby store the salt
water-mixed sherbet ice in the ice storage tank; and storing a
predetermined amount of the salt water-mixed sherbet ice with a
predetermined sherbet concentration at a predetermined low
temperature in the ice storage tank while the salt water-mixed
sherbet ice stored in the ice storage tank is refluxed from the ice
storage tank to the ice-maker repeatedly a plurality of times;
wherein water is injected into the salt water-mixed sherbet ice in
the process of producing salt water-mixed sherbet ice. Accordingly,
there is an effect that salt water-mixed sherbet ice at a
relatively high temperature can be produced easily.
[0014] This invention also provides an apparatus of producing salt
water-mixed sherbet ice, including: an ice-maker which generates
salt water-mixed sherbet ice under control based on a controller in
such a manner that ice generated by cooling salt water fed to the
ice-maker is scraped by scrapers to form small particles of ice to
thereby mix the small particles of ice with the salt water; an ice
storage tank which stores the salt water-mixed sherbet ice fed from
the ice-maker under control based on the controller; and a water
injecting unit which injects water into the salt water-mixed
sherbet ice; wherein control is performed by the controller so that
the salt water-mixed sherbet ice stored in the ice storage tank is
refluxed from the ice storage tank to the ice-maker and the
injection of water is performed by the water injecting unit in
steps of feeding the salt water-mixed sherbet ice from the
ice-maker to the ice storage tank and refluxing the salt
water-mixed sherbet ice from the ice storage tank to the ice-maker.
Accordingly, there can be achieved a salt water-mixed sherbet ice
producing apparatus which can produce salt water-mixed sherbet ice
at a relatively high temperature easily.
[0015] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a diagram showing Embodiment 1 of this invention
and showing an example of overall system configuration of a salt
water-mixed sherbet ice producing apparatus for carrying out a salt
water-mixed sherbet ice producing method;
[0017] FIG. 2 is a flow chart showing Embodiment 1 of this
invention and showing an example of a salt water-mixed sherbet ice
producing sequence in the salt water-mixed sherbet ice producing
method and the salt water-mixed sherbet ice producing apparatus
shown in FIG. 1;
[0018] FIG. 3 is a graph showing Embodiment 1 of this invention and
showing the relation between salt concentration and freezing point
due to the action of freezing-point depression;
[0019] FIG. 4 is a graph showing Embodiment 1 of this invention and
showing ice-making curves at salt concentrations of 1.0% to 4.5%
taken at intervals of 0.5%;
[0020] FIG. 5 is a graph showing Embodiment 1 of this invention and
showing an example of salt water state and ice-making curve in the
case where salt water-mixed sherbet ice is produced in the
condition of an initial salt water concentration of 2.5%, a target
salt water-mixed sherbet ice temperature of -1.5.degree. C. and a
target ice concentration (IPF) of 25% by the salt water-mixed
sherbet ice producing method and the salt water-mixed sherbet ice
producing apparatus shown in FIG. 1;
[0021] FIG. 6 is a diagram showing Embodiment 2 of this invention
and showing another example of overall system configuration of the
salt water-mixed sherbet ice producing apparatus for carrying out
the salt water-mixed sherbet ice producing method;
[0022] FIG. 7 is a flow chart showing Embodiment 2 of this
invention and showing an example of a salt water-mixed sherbet ice
producing sequence in the salt water-mixed sherbet ice producing
method and the salt water-mixed sherbet ice producing apparatus
shown in FIG. 6;
[0023] FIG. 8 is a graph showing Embodiment 2 of this invention and
showing an example of salt water state and ice-making curve in the
salt water-mixed sherbet ice producing method and the salt
water-mixed sherbet ice producing apparatus shown in FIG. 6;
[0024] FIG. 9 is a flow chart showing Embodiment 3 of this
invention and showing a further example of a salt water-mixed
sherbet ice producing sequence in the salt water-mixed sherbet ice
producing method and the salt water-mixed sherbet ice producing
apparatus;
[0025] FIG. 10 is a graph showing Embodiment 3 of this invention
and showing an example of salt water state and ice-making curve in
the salt water-mixed sherbet ice producing method and the salt
water-mixed sherbet ice producing sequence shown in FIG. 9;
[0026] FIG. 11 is a graph showing an example of salt water state
and ice-making curve showing the fact that salt water-mixed sherbet
ice can be produced in the condition of a target point range of
-1.5.degree. C. to -0.5.degree. C. and an IPF range of 15% to 25%
in the case of salt concentration C=3.0 in Embodiment 1 (without
any dewatering device) and Embodiment 3 (without any dewatering
device) of this invention; and
[0027] FIG. 12 is a graph showing an example of salt water state
and ice-making curve showing the fact that salt water-mixed sherbet
ice can be produced in the condition of a target point range of
-1.5.degree. C. to -0.5.degree. C. and an IPF range of 15% to 25%
in the case of salt concentration C=3.0 in Embodiment 2 (with a
dewatering device) of this invention.
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
[0028] Embodiment 1 of this invention will be described below with
reference to FIGS. 1 to 5. FIG. 1 is a diagram showing an example
of overall system configuration of a salt water-mixed sherbet ice
producing apparatus for carrying out a salt water-mixed sherbet ice
producing method. FIG. 2 is a flow chart showing an example of a
salt water-mixed sherbet ice producing sequence in the salt
water-mixed sherbet ice producing method and the salt water-mixed
sherbet ice producing apparatus shown in FIG. 1. FIG. 3 is a graph
showing the relation between salt concentration and freezing point
due to the action of freezing point depression. FIG. 4 is a graph
showing ice-making curves at salt concentrations of 1.0% to 4.5%
taken at intervals of 0.5%. FIG. 5 is a graph showing an example of
salt water state and ice-making curve in the case where salt
water-mixed sherbet ice is produced in the condition of an initial
salt concentration of 2.5%, a target salt water-mixed sherbet ice
temperature of -1.5.degree. C. and a target ice concentration (IPF)
of 25% by the salt water-mixed sherbet ice producing method and the
salt water-mixed sherbet ice producing apparatus shown in FIG.
1.
[0029] In FIG. 1, the salt water-mixed sherbet ice producing
apparatus has: an ice-maker (also called ice generator) 1; a drive
source (a motor for driving a rotary cylinder 1f (which will be
described later) in this Embodiment 1) 2 for the ice-maker 1; an
ice-maker load detection sensor (a current sensor, an ammeter,
etc.) 3 for detecting the load state of the ice-maker 1; a
refrigerator 4; a compressor 5; a condenser 6; a cooling medium
piping 7; an expansion valve 8; a pressure sensor 9; a temperature
sensor 10Ts; a main circulating pump 11; a pump controller 11a such
as an inverter, etc.; a reflux path piping (ice-maker 1.rarw.ice
storage tank 14 (salt water or salt water-mixed sherbet ice 143 is
fed from the ice storage tank 14 to the ice-maker 1 by the main
circulating pump 11)) 12; a fresh water temperature sensor 12Tw; a
flux path piping (ice-maker.fwdarw.ice storage tank (salt
water-mixed sherbet ice 143 is fed from the ice-maker 1 to the ice
storage tank 14 by the main circulating pump 11)) 13; the ice
storage tank 14 for storing a mixture 143 of sherbet ice and salt
water (i.e. salt water-mixed sherbet ice); a salt water-mixed
sherbet ice discharging path 141; a drain path 142; a salt
water-mixed sherbet ice discharging path switching valve 14a; a
drain path switching valve 14b; a salt water-mixed sherbet ice
storage level sensor 14cLs for detecting the storage level of salt
water-mixed sherbet ice in the ice storage tank 14; a stirrer (also
called agitator) 16 driven by a drive source (e.g. a motor) 15; a
first valve 19 for the ice storage tank 14; a second valve 21 for
the ice storage tank 14; a salt concentration adjusting tank 22; a
salt water injection pipe 231 for injecting salt water 23 such as
sea water from a salt water source (not shown) into the ice storage
tank 14; a fresh water injection pipe 241 for injecting fresh water
24 from a fresh water source (not shown) into the ice storage tank
14; a fresh water amount adjusting valve 25 for controlling the
amount of fresh water 24 injected into the ice storage tank 14; a
salt concentration sensor 26cl for detecting the salt concentration
C of salt water-mixed sherbet ice 143 in the ice storage tank 14; a
cold salt water feed control valve 28 for controlling the amount of
cold salt water injected into the ice storage tank 14; and a
controller 100 provided with a setting portion 110.
[0030] The ice-maker 1 has: a cooling medium side passage 1a
provided with an evaporator function; a salt water side passage 1b;
scrapers (also called scraping machines or scraping blades) 1c; an
outer cylinder 1d; an inner cylinder 1e; and the rotary cylinder
1f. The cooling medium side passage 1a is formed between the outer
cylinder 1d and the inner cylinder 1e so that the cooling medium
side passage 1a is shaped like a cylinder. The salt water side
passage 1b is formed between the rotary cylinder 1f and the inner
cylinder 1e so that the salt water side passage 1b is shaped like a
cylinder. The scrapers 1c are attached to an outer circumference of
the rotary cylinder 1f at regular intervals both in a
circumferential direction and in a direction of extension of a
center line so that the scrapers 1c are disposed in the salt water
side passage 1b.
[0031] The salt water-mixed sherbet ice discharging path switching
valve 14a for opening and closing the salt water-mixed sherbet ice
discharging path 141 is provided in the salt water-mixed sherbet
ice discharging path 141 provided in a side wall of the ice storage
tank 14 near the bottom of the ice storage tank 14.
[0032] The drain path switching valve 14b for opening and closing
the drain path 142 is provided in the drain path 142 provided in
the bottom of the ice storage tank 14.
[0033] The salt water-mixed sherbet ice storage level sensor 14cLs
for detecting the storage level of salt water-mixed sherbet ice 143
in the ice storage tank 14 is provided in the ice storage tank
14.
[0034] The controller 100 receives detection outputs of the
respective sensors 3, 9, 10Ts, 12Tw, 14cLs and 26cl and controls
the respective drive sources 2 and 15, the refrigerator 4, the
respective valves 8, 14a, 14b, 19, 21 and 28 and the pump
controller 11a to execute the salt water-mixed sherbet ice
producing sequence in the salt water-mixed sherbet ice producing
method and the salt water-mixed sherbet ice producing apparatus
shown in FIGS. 2, 5 and 7 which will be described later.
[0035] The setting portion 110 in the controller 100 sets a target
point, etc. which will be described later.
[0036] A salt water feed unit is formed from the salt water source
(not shown), the salt water injection pipe 231 and the cold salt
water feed control valve 28. A fresh water feed unit is formed from
the fresh water source (not shown), the fresh water injection pipe
241 and the fresh water amount adjusting valve 25.
[0037] An overall schematic operation of the salt water-mixed
sherbet ice producing method and apparatus will be described below
with reference to FIG. 1.
[0038] When the producing apparatus is powered on so that the
controller 100 starts, salt water in the salt water source, for
example, with a salt concentration of 2.5%, 3%, 3.5%, etc. selected
by a user is injected into the ice storage tank 14 through the cold
salt water feed control valve 28 so as to be stored in the ice
storage tank 14.
[0039] The salt water stored in the ice storage tank 14 is thrown
into the salt water side passage 1b of the ice-maker (ice
generator) 1 by the circulating pump 11. A cooling medium liquid at
about -12.degree. C. fed from the refrigerator 4 flows in the
cooling medium side passage 1a of the ice-maker 1.
[0040] The salt water having the predetermined salt concentration
and the predetermined temperature flows in the salt water side
passage 1b of the ice-maker 1 and comes into contact with an inner
circumferential surface (heat transmission surface) of the inner
cylinder 1e of the ice-maker 1, so that the salt water in contact
with the inner circumferential surface of the inner cylinder 1e is
cooled with the cooling medium in the cooling medium side passage
1a. In this manner, ice is generated on the inner circumferential
surface of the inner cylinder 1e.
[0041] The ice generated on the inner circumferential surface of
the inner cylinder 1e is scraped by the scrapers (scraping blades)
1c on the outer circumference of the rotary cylinder 1f which are
driven to rotate by the ice-maker drive source (rotary cylinder
drive motor) 2.
[0042] The ice scraped by the scrapers 1c is provided as particles
with a size of about 0.1 mm. The ice particles float in the salt
water in the salt water side passage 1b of the ice-maker 1 so as to
be shaped like sherbet containing salt water. That is, salt
water-mixed sherbet ice is generated.
[0043] The salt water-mixed sherbet ice generated in the salt water
side passage 1b of the ice-maker 1 is extruded from the salt water
side passage 1b by the circulating pump 11 so as to be fed into the
ice storage tank 14 via the flux path piping 13. Thus, the salt
water-mixed sherbet ice is stored in the ice storage tank 14.
[0044] The salt water-mixed sherbet ice 143 stored in the ice
storage tank 14 is refluxed into the salt water side passage 1b of
the ice-maker 1 via the reflux path piping 12 by the circulating
pump 11. Thus, ice is generated on the inner circumferential
surface of the inner cylinder 1e in the same manner as described
above. The ice is scraped by the scrapers 1c, so that salt
water-mixed sherbet ice containing a large amount of ice particles
is generated in the salt water side passage 1b.
[0045] The salt water-mixed sherbet ice containing such an
increasing amount of ice particles is further extruded from the
salt water side passage 1b by the circulating pump 11 in the same
manner as described above. Thus, the salt water-mixed sherbet ice
is fed into the ice storage tank 14 via the flux path piping 13, so
that the salt water-mixed sherbet ice is stored in the ice storage
tank 14.
[0046] The flux and reflex cycle including reflux of salt
water-mixed sherbet ice from the ice storage tank 14 into the salt
water side passage 1b, generation of salt water-mixed sherbet ice
containing a large amount of ice particles in the salt water side
passage 1b and flux of the salt water-mixed sherbet ice containing
a large amount of ice particles from the salt water side passage 1b
into the ice storage tank 14 is repeated many times so that a
predetermined amount of salt water-mixed sherbet ice 143 with a
predetermined sherbet concentration IPF is stored in the ice
storage tank 14.
[0047] In this manner, since it is impossible to obtain salt
water-mixed sherbet ice 143 with a predetermined sherbet
concentration when salt water is passed through the ice-maker 1
once, the flux and reflux cycle is repeated many times to thereby
gradually generate salt water-mixed sherbet ice 143 with a
predetermined sherbet concentration.
[0048] For example, to generate 10 tons of salt water-mixed sherbet
ice 143 with a predetermined sherbet concentration of 30%, the flux
and reflux cycle is repeated for about 10 hours to thereby
gradually generate the salt water-mixed sherbet ice 143.
Accordingly, since a large amount of ice cannot be generated in the
salt water side passage 1b of the ice-maker 1 in a short time, the
locked state in which the ice-maker cannot operate (the rotary
cylinder 1f cannot rotate) is almost prevented from being caused by
aggregation due to solidification of sherbet ice, compared with the
method and apparatus according to the background art.
[0049] Incidentally, as the flux and reflux cycle is repeated, the
sherbet concentration of salt water-mixed sherbet ice increases
gradually and the viscosity thereof increases gradually. The
gradual increase in the sherbet concentration of salt water-mixed
sherbet ice and in the viscosity thereof means that the ice-maker 1
gets close to a state in which the ice-maker 1 is overloaded and to
a state in which the ice-maker 1 is locked. Accordingly, although
the locked state can be almost prevented in Embodiment 1 of the
invention as described above, it is necessary to take measures to
prevent the locked state, for example, even when sudden drop in the
ambient temperature due to sudden change in the weather, repetition
of momentary power failure, etc. occurred, so that a more reliable
salt water-mixed sherbet ice producing method and apparatus can be
achieved.
[0050] When the sherbet concentration of salt water-mixed sherbet
ice becomes too high, for example, when the sherbet concentration
exceeds 50% and becomes a considerably high value of 60%, 70% or
80%, the viscosity of the salt water-mixed sherbet ice 143 becomes
so high that not only does forced circulation of the salt
water-mixed sherbet ice into the salt water side passage 1b of the
ice-maker 1 by the circulating pump 11 become difficult but also
the drive source (rotary cylinder drive motor) 2 of the ice-maker
becomes high-loaded and overloaded successively and stops finally.
Therefore, when salt water-mixed sherbet ice with a proper sherbet
concentration, for example, with a sherbet concentration of 30% has
been generated, the controller 100 stops the refrigerator 4 to stop
ice-making so that sherbet ice cannot be produced any more. On this
occasion, the judgment in the controller 100 as to whether the
proper sherbet concentration is obtained is, for example, based on
the temperature of salt water-mixed sherbet ice measured by the
temperature sensor 10Ts. That is, when the temperature of salt
water-mixed sherbet ice reaches a specified temperature, the
refrigerator 4 is stopped. In other words, the proper ice
concentration IPF is detected based on the temperature of salt
water-mixed sherbet ice corresponding to the salt concentration, so
that the operation of the refrigerator 4 is stopped in accordance
with detection of the proper ice concentration IPF of salt
water-mixed sherbet ice.
[0051] In this manner, the temperature of salt water-mixed sherbet
ice is monitored to control the operation of the refrigerator 4 so
that overloading and stopping of the ice-maker 1 can be prevented
from being caused by excess of the sherbet concentration.
[0052] Incidentally, the specified temperature depends on the salt
concentration of sea water. For example, the specified temperature
is -3.1.degree. C. for a salt concentration of 3.5%, and
-2.1.degree. C. for a salt concentration of 2.5%. -3.1.degree. C.
is lower than -2.1.degree. C. The salt concentration of sea water
varies according to environment. For example, the salt
concentration becomes low just after a heavy rain or near a river
estuary. Accordingly, when the salt concentration is lowered, it is
necessary to increase the specified temperature in accordance with
a value detected by the salt concentration sensor 26cl and stop the
refrigerator 4 quickly after the sherbet concentration reaches a
proper concentration. However, the theory and practice are not
always consistent with each other even when the specified
temperature is increased because the salt concentration is lowered.
That is, salt water-mixed sherbet ice with a higher sherbet
concentration than the theoretically estimated value thereof is
generated so that the viscosity of the salt water-mixed sherbet ice
becomes high. Accordingly, not only does forced circulation of the
salt water-mixed sherbet ice into the salt water side passage 1b of
the ice-maker 1 by the circulating pump 11 become difficult, but
also the ice-maker drive source (rotary cylinder drive motor) 2 may
be stopped because of high load. Moreover, when the sherbet
concentration becomes further higher, there is fear that ice in the
salt water-mixed sherbet ice in the salt water side passage 1b of
the ice-maker 1 may grow up so that the volume of ice increases to
thereby break the body of the ice-maker 1.
[0053] Therefore, when the load on the drive source 2 increases,
the controller 100 controls the pump controller (inverter) 11a
automatically, in accordance with the output of the ice-maker load
detection sensor (current sensor) 3 detecting the load state of the
drive source 2 driving the rotary cylinder 1f of the ice-maker 1,
to increase the output of the circulating pump 11, increase the
discharging pressure of the circulating pump 11 and forcedly
extrude salt water-mixed sherbet ice from the salt water side
passage 1b to the flux path piping 13 at the initial stage of
solidification of sherbet ice to thereby present the ice-maker 1
from lapsing into the overload state or the locked state.
Incidentally, when the load on the ice-maker 1 reaches a
predetermined value or higher, the user may be informed of the
overload state through a buzzer, voice, etc. so that the output of
the circulating pump 11 can be increased manually when the user is
informed of the overload state. Although the cost of the apparatus
becomes slightly low when such a manual operation is used, there is
fear that the timing to increase the output of the circulating pump
11 may be delayed or the increasing amount of the output of the
circulating pump 11 may be small. To prevent such a disadvantage,
it is preferable that the circulating pump 11 is controlled
automatically by the controller 100.
[0054] Under the state in which the flux and reflux cycle is
repeated many times by the controller 100, the salt water feed
control valve 28 is closed by the controller 100. On the other
hand, under the state in which the flux and reflux cycle is
repeated many times, when the target ice concentration IPF of the
salt water-mixed sherbet ice is, for example, 25%, the temperature
of a mixture of sherbet ice and salt water in the salt water side
passage 1b is normally -1.9.degree. C., for example, for a salt
concentration of 2.5%. The temperature reaches about -2.7.degree.
C. for a salt concentration of 3.5%.
[0055] Therefore, in Embodiment 1 of the invention, in addition to
the automatic control of the output of the circulating pump 11
based on the output of the ice-maker load detection sensor 3, the
output of the temperature sensor 10Ts is used so that automatic
control is performed by the controller in such a manner that
ice-making is continued until the ice concentration IPF of the salt
water-mixed sherbet ice reaches the target value, for example,
until the ice concentration IPF reaches 35% when the target ice
concentration IPF is 25%; the fresh water amount adjusting valve 25
is opened to feed fresh water 24 from the fresh water injection
pipe 241 into the ice storage tank 14 when the temperature detected
by the temperature sensor 10Ts reaches -2.3.degree. C.
corresponding to the ice concentration IPF of 35%, for example,
when the salt concentration C is 2.5%; and the fresh water amount
adjusting valve 25 is closed to stop the feed of fresh water 24
into the ice storage tank 14 when the temperature detected by the
temperature sensor 10Ts reaches the target value, for example,
-1.5.degree. C. In this manner, salt water-mixed sherbet ice at a
relatively high temperature (e.g. of -1.5.degree. C.) can be easily
produced from salt water having a high salt concentration.
[0056] In the method in which ice generated by cooling salt water
is scraped by the scrapers 1c as in the ice-maker 1 in this
Embodiment 1, when the salt concentration of the salt water is low,
the generated ice cannot be scraped because the generated ice is
hard. That is, since it is impossible to scrape ice when salt water
having a salt concentration lower than 2.5% is used, it is
necessary to use salt water having a salt concentration of 2.5% or
higher.
[0057] However, when salt water having a salt concentration of 2.5%
or higher is used, the temperature at which ice generation starts
is -1.5.degree. C., ice is generated as it is, and the temperature
at which the ice concentration IPF reaches 30% is -2.1.degree. C.
The salt water-mixed sherbet ice at -2.1.degree. C. cannot be
applied to cooling of some kind of fish because fish meat may be
frozen when the salt water-mixed sherbet ice is applied to cooling
of fish.
[0058] Therefore, in this Embodiment 1, the output of the
temperature sensor 10Ts is used so that automatic control is
performed by the controller in such a manner that ice-making is
continued until the temperature of the salt water-mixed sherbet ice
becomes the target value or higher; the fresh water amount
adjusting valve 25 is opened to feed fresh water 24 from the fresh
water injection pipe 241 into the ice storage tank 14 when the
temperature of the salt water-mixed sherbet ice reaches, for
example, -2.3.degree. C.; and the fresh water amount adjusting
valve 25 is closed to stop the feed of fresh water 24 into the ice
storage tank 14 when the detected temperature of the temperature
sensor 10Ts reaches the target value, for example, -1.5.degree. C.
In this manner, salt water-mixed sherbet ice at a relatively high
temperature (e.g. of -1.5.degree. C.) can be easily produced from
salt water having a high salt concentration.
[0059] The operation sequence in the controller 100 which is a
process of producing salt water-mixed sherbet ice based on
ice-making and injection of fresh water will be described below
with reference to FIG. 2.
[0060] In FIG. 2, first, the finished temperature (target
temperature) Ts2 and finished IPF (target IPF (ice concentration))
of salt water-mixed sherbet ice are set in the setting portion 110
of the controller 100 (step ST201).
[0061] Then, salt water is injected from the salt water injection
pipe 231 into the ice storage tank 14. Further, the salt
concentration C of salt water in the ice storage tank 14 is
measured by the salt concentration sensor 26cl and the level (water
level) of salt water in the ice storage tank 14 is measured by the
salt water-mixed sherbet ice storage level sensor 14cLs (step
ST202).
[0062] Then, the ice-making completion temperature Ts1 is set in
the setting portion 110 of the controller 100 (step ST203).
[0063] Then, the first and second valves 19 and 21 are opened, the
main circulating pump 11 is operated and the ice-maker 1 and the
refrigerator 4 are operated to perform ice-making (step ST204).
[0064] Then, whether or not the temperature Ts of salt water-mixed
sherbet ice which is the output of the temperature sensor 10Ts has
reached the ice-making completion temperature Ts1 (the set value of
which is, for example, about -2.2.degree. C. when the salt
concentration C is 2.5%) is judged based on measurement information
of the temperature Ts (step ST205).
[0065] When a result of the judgment in the step ST205 shows NO
(the temperature Ts has not reached the ice-making completion
temperature Ts1), ice-making is continued.
[0066] On the other hand, when a result of the judgment in the step
ST205 shows YES (the temperature Ts has reached the ice-making
completion temperature Ts1), ice-making is stopped (step
ST206).
[0067] The steps ST201 to ST206 are an operation sequence for
settings in a standard ice-making function portion 101 of the
controller 100. This operation sequence is the same as the
operation sequence in steps of the salt water-mixed sherbet ice
producing method according to the background art, except the
setting of the finished temperature (target temperature) Ts2 of
salt water-mixed sherbet ice. In the steps ST201 to ST206, salt
water-mixed sherbet ice at a low temperature is generated.
[0068] Then, the fresh water amount adjusting valve 25 is opened so
that fresh water 24 is injected from the fresh water injection pipe
241 into the ice storage tank 14 (step ST207).
[0069] Then, whether or not the temperature Ts of salt water-mixed
sherbet ice which is the output of the temperature sensor 10Ts has
reached the finished temperature Ts2 (the set value of which is,
for example, -1.5.degree. C. when the salt concentration C is.
2.5%) is judged based on measurement information of the temperature
Ts (step S208).
[0070] When a result of the judgment in the step ST208 shows NO
(the temperature Ts has not reached the finished temperature Ts2),
injection of fresh water 24 is continued.
[0071] On the other hand, when a result of the judgment in the step
ST208 shows YES (the temperature Ts has reached the finished
temperature Ts2), the fresh water amount adjusting valve 25 is
closed to stop injection of fresh water 24 (step S209).
[0072] In the step ST209, salt water-mixed sherbet ice at a
relatively high temperature, for example, of -1.5.degree. C. as the
target value and with an IPF of 25% is finished. The finished salt
water-mixed sherbet ice at a relatively high temperature in the ice
storage tank 14 is then discharged from the salt water-mixed
sherbet ice discharging path 141 automatically or optionally (step
ST210).
[0073] The steps ST207 to ST209 are an operation sequence in a
fresh water injecting function portion 102 of the controller 100.
By the steps ST207 to ST209, salt water-mixed sherbet ice at a
required relatively high temperature can be produced easily.
[0074] Incidentally, the injection of fresh water is performed
while the salt water-mixed sherbet ice in the ice storage tank 14
is stirred by the stirrer 16 so that the temperature and IPF of the
salt water-mixed sherbet ice are uniformized in the whole region in
the ice storage tank 14.
[0075] Thermophysical properties of the salt water-mixed sherbet
ice will be described below.
[0076] The matter that salt water-mixed sherbet ice at a high
temperature can be produced when water is mixed with salt water
such as sea water as described above will be described below.
[0077] First, the freezing temperature of salt water will be
described. A salt water NaCl solution is not frozen at 0.degree. C.
which is the freezing point of fresh water, but frozen at a point
lower than 0.degree. C. because of the action of freezing point
depression.
[0078] FIG. 3 shows the relation between salt concentration and
freezing point due to the action of freezing point depression. When
salt water is further cooled after it begins to be frozen, ice is
generated so that the amount of ice increases. Moreover, since ice
itself is fresh water, the salt concentration of the remaining salt
water portion increases gradually. As the salt concentration
increases, the freezing point decreases. Accordingly, when
ice-making is continued, the amount of ice increases gradually and
the temperature decreases gradually as shown in FIG. 3.
[0079] The cold heat quantity of salt water-mixed sherbet ice is
defined as follows.
[0080] The cold heat quantity can be expressed in specific enthalpy
[kcal/kg] of salt water-mixed sherbet ice as follows:
h=cw.times.(1-Ipf).times.T+ci.times.Ipf.times.T-L.times.Ipf
in which h [kcal/kg] is the specific enthalpy of salt water-mixed
sherbet ice, c is specific heat, T is the temperature of salt
water-mixed sherbet ice, Ipf is the temperature of ice, and L is
latent heat of solidification of water.
[0081] In this expression, the subscript w is designated as water
and the subscript i is designated as ice.
[0082] When salt water is cooled, ice begins to be generated at the
freezing point and the temperature decreases little by little while
the amount of ice increases. The locus thereof varies according to
the initial salt concentration and the state thereof is shown in
FIG. 4. FIG. 4 shows states in salt concentrations of 1.0% to 4.5%
taken at intervals of 0.5%. In FIG. 4, the abscissa axis shows
enthalpy of salt water-mixed sherbet ice and the ordinate axis
shows temperature. In FIG. 4, IPF % shows ice concentration.
[0083] For example, when salt water with a salt concentration of
3.5% is cooled from 0.degree. C., it is cooled linearly. When the
temperature reaches -2.1.degree. C., salt water begins to be frozen
and the temperature thereof decreases while the amount of ice
increases. For example, when the ice concentration IPF of salt
water-mixed sherbet ice is 30%, the temperature reaches
-3.1.degree. C. and the specific enthalpy reaches about -26
kcal/kg.
[0084] Next, a state in the case where fresh water is added to the
salt water-mixed sherbet ice will be considered. When fresh water
at a temperature of 0.degree. C. or higher is added, the
temperature of the salt water-mixed sherbet ice increases and the
salt concentration of the salt water-mixed sherbet ice decreases
because the temperature of the salt water-mixed sherbet ice is
0.degree. C. or lower. Incidentally, a solution of ice mixed with
salt water, such as salt water-mixed ice water or sherbet ice, has
the property that the salt concentration thereof balances with the
freezing point. Accordingly, when fresh water is added to salt
water-mixed sherbet ice, part of ice in the salt water-mixed
sherbet ice is melted so that the salt concentration of the salt
water-mixed sherbet ice further decreases but the temperature of
the salt water-mixed sherbet ice decreases. Consequently, the salt
concentration of the salt water-mixed sherbet ice balances with the
freezing point.
[0085] For example, when fresh water is injected into salt
water-mixed sherbet ice having an ice concentration of 30% after
the salt water-mixed sherbet ice is cooled to the ice concentration
of 30% while produced with use of salt water having an initial salt
concentration of 3.5%, the temperature of the salt water-mixed
sherbet ice increases through the locus as shown in FIG. 4.
[0086] Incidentally, FIG. 4 shows states in the case where three
kinds of fresh water at 0.degree. C., 5.degree. C. and 10.degree.
C. are injected into salt water-mixed sherbet ice in the condition
that the amounts (weight ratios) of the added freshwater to the
salt water-mixed sherbet ice are 5%, 10%, 20%, . . . , 100%.
[0087] FIG. 5 is a graph showing another example of ice-making
curves in the case where the salt water-mixed sherbet ice is
produced from salt water having a salt concentration of 2.5% by the
steps ST204 to ST209 in the condition that the target point of
finished salt water-mixed sherbet ice is -1.5.degree. C. with an
IPF of 25%.
[0088] Because the ice-maker 1 in Embodiment 1 can generate ice
only when the initial salt concentration is 2.5% or higher as
described above, a 2.5% line as a reference is shown in FIG. 5. As
represented by the arrow in FIG. 5, ice is generated from salt
water having a salt concentration of 2.5% until the IPF reaches an
IPF (=35% in FIG. 5) higher by a predetermined value than the
target IPF (=25% in FIG. 5). At the point of time when the IPF
reaches the IPF (=35% in FIG. 5) higher by the predetermined value
(the temperature of salt water-mixed sherbet ice reaches
-2.2.degree. C.), ice-making is stopped and fresh water at
0.degree. C. is injected. It is found that salt water-mixed sherbet
ice at a relatively high temperature as the target point of the
target temperature (of -1.5.degree. C. in FIG. 5) and the target
IPF (of 25% in FIG. 5) can be obtained in this manner.
[0089] Although Embodiment 1 has been described upon the case where
fresh water is injected so as to be mixed with salt water having a
high salt concentration such as sea water, the aforementioned
properties hold even when the fresh water is replaced with salt
water. Even when thin salt water (salt water having a low salt
concentration) is injected so as to be mixed with salt water having
a high salt concentration such as sea water, it is possible to
increase the temperature of salt water-mixed sherbet ice. However,
the highest effect for increasing the temperature of salt
water-mixed sherbet ice can be obtained when salt water having a
salt concentration of 0, that is, fresh water is used.
[0090] In Embodiment 1, the drive source (rotary cylinder drive
motor) 2 of the ice-maker 1 and the main circulating pump 11 can
use a low-speed operating system or a variable-speed operating
system in accordance with necessity.
Embodiment 2
[0091] Embodiment 2 of this invention will be described below with
reference to FIGS. 6 to 8. FIG. 6 is a diagram showing another
example of overall system configuration of the salt water-mixed
sherbet ice producing apparatus for carrying out the salt
water-mixed sherbet ice producing method. FIG. 7 is a flowchart
showing an example of a salt water-mixed sherbet ice producing
sequence in the salt water-mixed sherbet ice producing method and
the salt water-mixed sherbet ice producing apparatus shown in FIG.
6. FIG. 8 is a graph showing an example of salt water state and
ice-making curve in the salt water-mixed sherbet ice producing
method and the salt water-mixed sherbet ice producing apparatus
shown in FIG. 6.
[0092] Embodiment 2 is configured so that a dewatering process is
added to the aforementioned Embodiment 1. Salt water-mixed sherbet
ice having an ice concentration IPF higher than that in Embodiment
1 can be produced in Embodiment 2.
[0093] That is, as shown in FIG. 6, a dewatering unit composed of a
dewatering pump 22, a dewatering pipe 221, a dewatering control
valve 22a and an integrating flowmeter 22b is added to the
apparatus shown in FIG. 1. As shown in FIG. 7, steps ST701 to ST705
are provided between the steps ST206 and ST207 in FIG. 2. The
amount of water to be removed is calculated (step ST7O1). The
stirrer 16 is stopped (step ST702). The dewatering pump 22 is
operated (step ST703). The amount of water removed from salt
water-mixed sherbet ice in the ice storage tank 14 is measured
based on the output of the integrating flowmeter 22b so that
dewatering is stopped when the amount of water removed from the
salt water-mixed sherbet ice reaches a predetermined value (step
ST704). The stirrer 16 is restarted (step S705).
[0094] Incidentally, the steps ST701 to ST705 are executed by a
dewatering function portion 103 of the controller 100.
[0095] According to Embodiment 2, it is found that salt water-mixed
sherbet ice at a relatively high temperature of -1.5.degree. C.
with an ice concentration IPF of 30% which is higher than the ice
concentration IPF of 25% in Embodiment 1 can be produced as
follows. As represented by the arrow in FIG. 8, after ice is
generated from salt water having a salt concentration of 2.5%,
dewatering is slightly performed by the dewatering unit and then
fresh water is injected or, in other words, water is removed from
the salt water-mixed sherbet ice before the injection of fresh
water.
Embodiment 3
[0096] Embodiment 3 of this invention will be described below with
reference to FIGS. 9 and 10. FIG. 9 is a flow chart showing a
further example of a salt water-mixed sherbet ice producing
sequence in the salt water-mixed sherbet ice producing method and
the salt water-mixed sherbet ice producing apparatus. FIG. 10 is a
graph showing an example of salt water state and ice-making curve
in the salt water-mixed sherbet ice producing method and the salt
water-mixed sherbet ice producing sequence shown in FIG. 9.
[0097] Embodiment 3 is configured so that the ice-making and the
injection of fresh water in Embodiment 1 are performed alternately
and repeatedly. Salt water-mixed sherbet ice having an ice
concentration IPF higher than that in Embodiment 1 can be produced
in Embodiment 3 similarly to Embodiment 2.
[0098] In Embodiment 3, as shown in FIG. 9, the steps ST201 to
ST206 are executed by a first standard ice-making function portion
101-1 of the controller 100. Then, steps ST701 to ST703 which are
the same as the steps ST207 to ST209 are executed by a first fresh
water injecting function portion 102-1. Then, steps ST704 to ST706
which are the same as the steps ST204 to ST206 are executed by a
second standard ice-making function portion 101-2. Then, the steps
ST207 to ST209 are executed by a second fresh water injecting
function portion 102-2.
[0099] According to Embodiment 3, it is found that salt water-mixed
sherbet ice having an ice concentration IPF higher than that in
Embodiment 1 can be produced like Embodiment 2 in the following
manner. As represented by the arrow in FIG. 10, ice-making and
injection of fresh water are performed alternately and repeatedly
several times.
[0100] Incidentally, in the case where salt water having a salt
concentration of 3.0% is used by way of example, as shown in FIG.
11, salt water-mixed sherbet ice in a temperature range of
-1.5.degree. C. to -0.5.degree. C. and an IPF range of 15% to 25%
in a region surrounded by K-B-C-D-M can be produced in Embodiment 1
(without any dewatering unit) and Embodiment 3 (without any
dewatering unit).
[0101] By one fresh water injecting cycle, the temperature and IPF
of salt water-mixed sherbet ice can be adjusted in a region
surrounded by E-C-F. By two fresh water injecting cycles and one
ice-remaking cycle, the temperature and IPF of salt water-mixed
sherbet ice can be adjusted in a region surrounded by G-C-D-H. By a
plurality of fresh water injecting cycles and ice-remaking cycles,
the temperature and IPF of salt water-mixed sherbet ice can be
adjusted in a region surrounded by K-B-C-D-M.
[0102] The region surrounded by A-K-M is a region in which
dewatering is essential. Unless the dewatering process in
Embodiment 2 is provided, the temperature and IPF of salt
water-mixed sherbet ice cannot be adjusted in the region surrounded
by A-K-M.
[0103] As shown in FIG. 12, salt water-mixed sherbet ice in a
temperature range of -1.5.degree. C. to -0.5.degree. C. and an IPF
range of 15% to 25% in a region surrounded by A-B-C-D can be
produced in Embodiment 2 (with a dewatering unit).
[0104] By one fresh water injecting cycle, the temperature and IPF
of salt water-mixed sherbet ice can be adjusted in a region
surrounded by E-C-F. By one dewatering and fresh water injecting
cycle, the temperature and IPF of salt water-mixed sherbet ice can
be adjusted in a region surrounded by A-B-C-D.
[0105] Incidentally, the term "salt water" used in Embodiments 1 to
3 means so-called salt water such as salt water obtained by mixing
salt and water or sea water.
[0106] Although Embodiments 1 to 3 have been described upon the
case where the injection of fresh water and dewatering are
controlled by the controller 100 used commonly, the injection of
fresh water and dewatering may be controlled by another controller
provided separately from the controller 100. In this case, the
controller can be easily added to the existing salt water-mixed
sherbet ice producing apparatus.
[0107] In FIGS. 1 to 12, identical or equivalent parts are referred
to by the same numerals. In Embodiments 2 and 3, description of
parts identical or equivalent to those in Embodiment 1 is omitted
as a rule.
[0108] Various modifications and alterations of this invention will
be apparent to those skilled in the art without departing from the
scope and spirit of this invention, and it should be understood
that this is not limited to the illustrative embodiments set forth
herein.
* * * * *