Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing
Reexamination Certificate
2000-06-26
2004-01-06
Thornton, Krisanne (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
C099S453000, C099S461000, C422S026000, C422S039000, C422S295000, C426S521000
Reexamination Certificate
active
06673311
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and apparatus for continuous heat sterilization of liquid. Particularly, the present invention relates to a method for continuous heat sterilization of liquid including a preheating step, a final heating step, a retaining step and a cooling step, and to an apparatus for performing this method.
BACKGROUND ART
Conventionally, as a sterilizing method for food, there has been widely adopted a heat sterilization method for heating food at high temperatures. Food is classified into liquid-like food or solid-like food, depending on whether convection is predominant or conduction is predominant in a mechanism of heat transfer when the food is heated, and is also classified into paste-like food as food showing properties between properties of liquid-like food and solid-like food.
As methods of heat sterilization of liquid-like or paste-like food, there is a pre-filling sterilizing method in which food is heated and sterilized before being filled into a container, filled and hermetically sealed in the container while remaining at high temperatures, cooled in a sterilized manner and filled in a sterilized atmosphere into the container in a sterilized state. There is also a post-filling sterilizing method in which food is filled into a container, hermetically sealed, and thereafter heated along with the container to thereby sterilize the food. Further, the former pre-filling sterilizing method is classified into a case in which food is continuously heated, and a case in which food is batch heated by a double can (refer to “Food Engineering Basic Course, volume 10, Food Reaction Engineering”, Kiyoshi Kubota et al., page 111, Korin Kabushiki Kaisha, Sep. 29, 1990).
Generally, when liquid as in liquid-like food or paste-like food is heated and sterilized, there is carried out a continuous heat sterilization method of an HTST method, a UHT method or the like in which mass processing is feasible. An explanation will be given of an example of a conventional continuous heat sterilization method of liquid with reference to FIG.
4
.
FIG. 4
is a schematic view for explaining an example of a conventional continuous heat sterilization apparatus for liquid.
In
FIG. 4
, a conventional apparatus
1
c
for continuous heat sterilization of liquid includes a feed pump
3
connected to a storage tank
2
for liquid. In
FIG. 4
, a rotary type constant amount pump is used as the feed pump
3
. Although the feed pump of
FIG. 4
is formed with a pipe for returning liquid from an outlet pipe to an inlet pipe, and the pipes are installed with a flow regulating valve, illustration thereof is omitted in FIG.
4
. By returning liquid from an outlet side to an inlet side of the feed pump by the pipes, and regulating an amount of return by the flow regulating valve, pressure on an outlet side of the feed pump or a flow rate of pressure-fed liquid is regulated. On the outlet side of the feed pump
3
, there is formed a flow pass of liquid connected with a preheating section
10
, a low pressure homogenizer
20
, a final heating section
35
, a holding pipe
4
, a first cooling section
40
, a second cooling section
50
and a back pressure regulating valve
5
in this order, and a sterilized liquid outlet
6
. Further, all of the preheating section
10
, the final heating section
35
, the first cooling section
40
and the second cooling section
50
for carrying out heat exchange are constituted by plate type heat exchangers.
Liquid stored in the storage tank
2
is pressure-fed to the preheating section
10
by the feed pump
3
. In the preheating section
10
steam is introduced from a steam source
11
and subjected to heat exchange with liquid, and liquid is preheated to reach a predetermined preheating temperature. A temperature sensor
14
is installed at an outlet of the preheating section
10
, an opening amount of a steam regulating valve
15
is regulated in accordance with temperature of liquid, and a temperature of liquid is controlled to a predetermined preheating temperature. The preheating temperature is generally about 40° to 90° C. Vapor-condensed water resulting from heat exchange is discharged via a trap pipe
12
or a discharge pipe
13
. Liquid reaching the predetermined preheating temperature is pressure-fed to the low pressure homogenizer
20
. A preheating step is carried out by the preheating section
10
.
As a principle, the low pressure homogenizer
20
is provided when liquid includes fat, and is an apparatus for homogenizing the liquid by destructing fat balls in the liquid. Generally, a homogenizer is installed with a high pressure pump and a homogenizing valve (not illustrated), in either of a case of a low pressure homogenizer and a high pressure homogenizer, mentioned later. A high pressure pump is an apparatus in which a pressurizing chamber of a predetermined volume, having an inlet and an outlet for liquid, is provided with a plunger reciprocating in directions for increasing and decreasing the volume of the pressurizing chamber, and check valves are installed at the inlet and the outlet of the pressurizing chamber. Volume of the pressurizing chamber is increased and decreased by reciprocation of the plunger, and the check valves are naturally opened and closed in accordance with an increase and decrease of the volume to thereby suck and deliver liquid.
A homogenizing valve is a kind of a throttle valve for regulating a clearance of a flow pass for liquid delivered from a high pressure pump. That is, the homogenizing valve pressurizes liquid by throttling the clearance of the flow pass for liquid. Further, the homogenizing valve makes liquid pressurized in this way pass in a narrow flow pass and releases it to normal pressure, and destructs fat balls in the liquid during this occasion. Generally, pressure caused by narrowing a flow path by a homogenizing valve is referred to as homogenizing pressure. As a principle, homogenizing pressure of the low pressure homogenizer
20
is regulated within a range of from about 2 to 40 MPa.
Further, the low pressure homogenizer
20
is provided with a hydraulic control unit
21
. The hydraulic control unit
21
is provided with a hydraulic pump and a hydraulic valve (both of which are not illustrated). Pressure is applied to oil by the hydraulic pump, the pressure is regulated by the hydraulic valve and thereafter, a homogenizing valve is operated by pressure of the oil to thereby regulate homogenizing pressure.
Generally, it is preferable to carry out a homogenizing operation with liquid at high temperature, and the low pressure homogenizer
20
is frequently provided downstream of the preheating section
10
, however, there is a case in which the homogenizer
20
is installed downstream of the final heating section
35
. In this case, liquid which comes out from the final heating section
35
is cooled, and thereafter made to pass through the low pressure homogenizer
20
. Liquid passing through the low pressure homogenizer
20
is liquid after sterilization, and accordingly, the low pressure homogenizer
20
is to be sterilized. The low pressure homogenizer
20
specified to be sterilized, is provided with a structure in which, for example, steam or sterilized water is always supplied to seal portions of the plunger to thereby prevent contamination of liquid, and generally an apparatus cost and running cost are higher than those of an apparatus not specified to be sterilized. Further, the low pressure homogenizer
20
is installed with a bypass pipe
22
which is used only during cleaning for ensuring a flow rate of cleaning solution.
Liquid which comes out from such low pressure homogenizer
20
is fed to the final heating section
35
. The final heating section
35
is a heat exchanger for elevating a temperature of liquid to a predetermined sterilizing temperature. The final heating section
35
is provided with a hot water producing device
36
which circulates hot water via a hot water circulating pass
37
to thereby heat liquid to reach the predetermined sterilizing temp
Asano Yuzo
Iwatsuki Keiji
Matsui Hiroaki
Mizota Teruhiko
Mizota Yasutatsu
Morinaga Milk Industry Co. Ltd.
Thornton Krisanne
Wenderoth , Lind & Ponack, L.L.P.
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