JPH08322463A - Device for pasteurizing milk - Google Patents

Abstract

PURPOSE: To provide a milk-pasteurizing device capable of equally thermally insulating and pasteurizing milk, reducing the number of valves and easily equally washing and pasteurizing the milk. CONSTITUTION: Milk is delivered into a balance tank 2 through a multiplate 1. The milk is delivered from a sanitary pump 3 into the hot water-heating part 5b of a heat exchanger 5 through a flow passageway 4a and preliminarily heated in the part 5b. The pre-heated milk is delivered to the steam-heating part 5a of the heat exchanger 5 through a homogenizer 11, and again heated to 65 deg.C there. The milk is allowed to pass through the flow passageway 4d of a holding tube unit 12, and held to 65 deg.C during the passage to pasteurize the milk at the low temperature. The milk is delivered from a vane pump 14 into the underground cooling part 5c and the chilled water-cooling part 5d of the heat exchanger 5 through a low passageway 4e, and cooled to approximately 5 deg.C. The treated milk is further delivered to a surge tank 15 through a flow passageway 4f and stored in the tank.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a milk sterilizer for pasteurizing milk.

[0002]

2. Description of the Related Art Conventionally, as a sterilizer of this type, there is one shown in FIG. 16, for example. In the figure, milk flows into the balance tank 102 through the flow pipe 101 _-1 , and is stored there. The pump 103 pumps out the milk in the balance tank 102 and sends the milk to the heat exchanger 104.

On the other hand, for example, two holding tanks 105 _-4 and 105 _-5 store hot water at 65 ° C. in advance. These holding tanks 105 _-4 , 10
Hot water in 5 _-5 is passed through the flow pipe 101 _-3 to the heat exchanger 10
4 through the heat exchanger 104 and then drained through an appropriate drain valve. Further, hot water of 65 ° C. is circulated between the water heater 106 and the heat exchanger 104.

In the heat exchanger 104, the hot water from the holding tanks 105 _-4 and 105 _-5 , and the water heater 106.
Milk from the balance tank 102 is warmed up to 65 ° C. by hot water from.

After this, this milk is homogenized by 10
7, the fat globules contained in milk are broken down here,
This milk is homogenized. In addition, this milk is
It flows into the empty holding tank 105 _-1 through 01 _-2 and is stored there.

[0006] Also after becoming the holding tank 105 _-1 and filled with milk, if there remain milk balance tank 102, from the milk passes through the heat exchanger 104 and homogenizer 107, 2 It is stored in the second holding tank 105 _-2 . .

Each holding tank 105 _{-1 to} 105
_-5 is covered with the respective hot water jackets, and these holding tanks 105 _{-1 to} 105
_-5 is kept at 65 ℃. For this reason, the milk in the holding tank is kept at 65 ° C., and after 30 minutes have passed and the pasteurization is completed, the milk is sent from the holding tank to the heat exchanger 104 through the flow pipe 101 _-3 .

[0008] In the course of the past, the holding tank 105 _-4, fed hot water every 105 within _-5, these holding tank 105 _-4, 105 _-5 is empty. Therefore, the second holding tank 1
Following 05 _-2 , milk can be continuously stored in these holding tanks 105 _-3 , 105 _-4 , 105 _{-5 in} the order of the third, fourth and fifth holding tanks.

Each holding tank 105 _-4 , 105
_When all of the warm water in _-5 is sent out, the milk in the holding tank is warmed by the milk in the holding tank instead of the warm water. That is, the heat exchanger 10
In 4, for example, milk from the holding tank 105 _-1, and the hot water from the water heater 106, milk from the balance tank 102 can be warmed up to 65 ° C.. The milk from the balance tank 102 is guided from the heat exchanger 104 through the homogenizer 107 to the third holding tank 105 _-3 and stored there.

In the heat exchanger 104, the water from the water supplier 108 circulates and the chilled water supplier 1
09 chilled water are circulated from, these water and milk from the balance tank 102, the milk from the holding tank 105 _-1 is cooled. The cooled milk is guided to each surge tank 111 through the flow pipe 101 _-4 and stored therein.

Similarly, each holding tank 105 _-2
The milk within ~ 105 _-5 is cooled by the heat exchanger 104 after waiting for 30 minutes, and is sequentially guided to and stored in each surge tank 111.

[0012] Such sterilization treatment, milk is continued as long as the remaining balance tank 102, is repeated that each holding tank 105 _-1 to 105 _-5 is emptied or sequentially filled.

By the way, since this apparatus handles milk as food, it is necessary to perform cleaning and sterilization. For this reason, the cleaning water unit 112 and the steam unit 113 are attached to this apparatus.

The wash water unit 112 circulates wash water through the wash water pipes 114 indicated by the alternate long and short dash line to the flow pipe of the apparatus, each tank, etc., and sterilizes them. Similarly, the steam unit 113 circulates the steam through a steam pipe (not shown) to the flow pipe of the apparatus, each tank, etc. to sterilize them.

The sterilization with such washing water or steam is performed every time the milk is sterilized, whereby the apparatus is always kept clean.

[0016]

However, in the above-mentioned conventional apparatus, since the milk is temporarily stored in the holding tank, the amount of the milk that has flowed into this tank first,
The heat retention time was different from the amount of milk that later flowed into this tank, which was an adverse effect on the stabilization of milk quality.

Further, around the holding tank,
The number of valves tends to increase. Since these valves are difficult to clean and sterilize, it is desirable to have a small number of them. In other words, the presence of holding tanks made cleaning and sterilization difficult.

Further, when cleaning or sterilizing the inside of the holding tank, a large amount of cleaning water is required and a long time is spent. Moreover, it was difficult to clean every corner of the holding tank, and some parts could not be cleaned.

Therefore, an object of the present invention is to sterilize milk by keeping it warm without heat and sterilizing it, and having a small number of valves, which makes it possible to easily clean and sterilize every corner of the milk. To provide.

[0020]

In order to solve the above problems, in the sterilizing apparatus of the present invention, a balance tank for storing a liquid, a heating means, a heat retaining means, a cooling means,
A surge tank for storing the liquid, a distribution pipe from the balance tank to the surge tank through the heating means, the heat retaining means and the cooling means, a plurality of valves and at least one pump inserted in the middle of the distribution pipe, and the distribution pipe Is heated by the heating means, kept at a predetermined temperature by the heat retaining means, cooled by the cooling means, and the pump is a unit in which the liquid in the flow pipe spends a predetermined time and passes through the heat retaining means. The liquid in the balance tank is pumped to the surge tank through the flow pipe at a flow rate per hour.

[0021]

In the invention having the above-mentioned structure, the flow pipe is heated, kept warm and cooled by the heating means, the heat keeping means and the cooling means. The liquid in the flow pipe is pumped by a pump and spends a predetermined time to pass through the heat retaining means. Therefore, the liquid in the flow pipe is kept warm at a predetermined temperature for a predetermined time.

If the liquid is milk, the milk is
It is kept at a certain temperature for a certain time and sterilized. Moreover, milk is not stored in the holding tank but is kept warm while being sterilized while flowing in the distribution pipe, so that milk of a certain quality without spots can be obtained.

In addition, not having a holding tank for storing milk and keeping it warm leads to a reduction in the number of valves, and facilitates cleaning and sterilization. Further, since it is possible to wash every corner by only passing washing water through the flow pipe, and only one washing is required, it is possible to reduce the working time and the washing loss.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the milk sterilizing apparatus of the present invention. First, with reference to FIG. 1, an outline of the apparatus of this embodiment will be described.

In this apparatus, milk is guided to the balance tank 2 through the multi-plate 1 and temporarily stored there. The sanitary pump 3 pumps milk from the balance tank 2 and sends the milk to the heat exchanger 5 through the flow passage 4a.

The heat exchanger 5 includes a steam heating section 5a, a hot water heating section 5b, a ground water cooling section 5c, and a chilled water cooling section 5.
d. In the steam heating unit 5a, a steam pipe from the steam heating device 6 is connected, and the steam is circulated through the steam pipe to perform heating by the steam.
In the hot water heating unit 5b, a hot water pipe from the hot water heating device 7 is connected. The hot water is circulated through the hot water pipe to perform heating with the hot water. In the groundwater cooling unit 5c, a groundwater pipe from the groundwater pumping device 8 is piped, and groundwater is circulated through the groundwater pipe and cooled by the groundwater. In the chilled water cooling unit 5d, a chilled water pipe from the chilled water cooling device 9 is piped, and chilled water (water close to 0 ° C.) is circulated through the chilled water pipe to perform cooling by the chilled water.

The milk flow passage 4a is introduced into the hot water heating section 5b of the heat exchanger 5, where the milk is preheated. After this, the milk is homogenized through the flow passage 4a.
Leading to. The homogenizer 11 decomposes fat globules of milk to homogenize the milk and sends the milk to the heat exchanger 5 through the flow passage 4b.

The flow passage 4b is introduced into the steam heating section 5a of the heat exchanger 5, where the milk is reheated and its temperature reaches 65 ° C. This milk reaches the holding tube unit 12 through the flow passage 4c.

This holding tube unit 12
A milk flow passage 4d is provided in the pipe. Although this flow passage 4d is long, it is appropriately bent repeatedly to be housed in a small space. In addition, the steam pipe from the steam insulation device 13 is connected here,
Steam is introduced through this steam pipe, and the flow passage 4d is kept at 65 ° C. by this steam.

The milk is kept at 65 ° C. while passing through the flow passage 4d of the holding tube unit 12 and pasteurized.

This holding tube unit 12
The milk that has passed through reaches the vane pump 14, and is sent from the vane pump 14 to the heat exchanger 5 through the flow passage 4e. The milk flow passage 4e passes through the ground water cooling unit 5c and the chilled water cooling unit 5d of the heat exchanger 5, where the milk is cooled to about 5 ° C. Further, this milk is guided to the surge tank 15 through the flow passage 4f and stored therein.

The air purge switching valve 16, unit inlet switching valve 17, CIP valve 18, unit outlet valve 1
9, the drain valve 21, and the return switching valve 22 are electromagnetic valves, and are automatically switched or opened / closed in the control process described later. In addition, a plurality of manual valves 23a-23j
Are manually switched. Further, the plurality of side glasses 24a to 24h are glass tubes provided in the middle of the flow passage, and are provided to visually recognize the state inside the flow passage.

FIG. 2 is a block diagram showing the control system of this apparatus. In the figure, the operation panel 31 is an array of various operation switches and power switches, and is operated by the administrator of this device. The concentration sensor 32 is provided at the end of the flow pipe 4d and detects the concentration of milk or water passing through this portion. Heating temperature sensor 33
Is provided at the end of the flow passage 4b and detects the temperature of milk or water passing through this portion. Insulated temperature sensor 34
Is provided in the flow passage 4d immediately after the holding unit 12, and detects the temperature of milk or water at this portion.

Further, the timer 35 counts the predetermined times T ₁ , T ₂ and T ₃ . further,
The display unit 36 displays a light, and the chime 37 produces a chime sound.

The control device 38 controls the device in a centralized manner, and in response to the operation of the operation panel 31 or the detection output of each sensor, each of the valves 16 to 19, 21, 22 and
The pumps 3, 14, 39, the homogenizer 11, the steam heating device 6, the steam heat insulating device 13, and the like are controlled.

In this apparatus, before and after the step of sterilizing milk, the apparatus is sterilized with hot water, and the apparatus is washed and sterilized with cleaning water. That is, after sterilizing the device with boiling water, the process proceeds to the milk sterilization step, and finally, the device is washed and sterilized with cleaning water.

Such a processing procedure will be sequentially described with reference to the timing chart of FIG. 3 and FIGS. 4 to 13. 4 to 12 are the same as those in FIG. 1, but the portions through which milk or water passes are indicated by thick lines.

First, when the power switch of the operation panel 31 is turned on at the time point t ₀ in FIG. 3, the preliminary period n ₁ starts. In the preliminary period n ₁ , the unit inlet switching valve 17 is switched to the flow passage 4d side, the CIP valve 18 is opened, and the unit outlet valve 19 is opened. In this state, the faucet 41 is operated to add water to the balance tank 2, and one of the switches on the operation panel 31 is turned on to activate the sanitary pump 3. Further, after a while, the operation panel 31 is operated to activate the homogenizer 11.

As a result, the water flows through the balance tank 2 → sanitary pump 3 → flow passage 4a → homogenizer 11 → each flow passage 4b, 4c, 4d as shown in FIG. The balance tank 2 also circulates from the flow passage 4d through the return passage 42b.

On the other hand, the hot water heating device 7 is activated, and the hot water heating device 7 and the hot water heating portion 5b of the heat exchanger 5 are connected to each other by 45
Circulate warm water at ℃. Further, two of the switches on the operation panel 31 are turned on to activate the steam heating device 6 and the steam heat insulating device 13. At this time, the heating temperature sensor 33
The amount of steam that circulates between the steam heating device 6 and the steam heating section 5a of the heat exchanger 5 is adjusted so that the temperature detected by is 65 ° C. Similarly, the amount of steam circulated between the steam temperature keeping device 13 and the holding unit 12 is adjusted so that the temperature detected by the heat retention temperature sensor 34 becomes 65 ° C.

Next, when the operation panel 31 is operated at the time point t ₁ in FIG. 3 to set the sterilization preparation period n ₂ , the control device 38 activates the vane pump 14 in response to this, and the vane pump 14 is activated. Drive at high speed.

As a result, as shown in FIG. 5, the water is balanced tank 2 → sanitary pump 3 → flow passage 4a → homogenizer 11 → each flow passage 4b, 4c, 4d, 4e, 4
It circulates in the route of f → return path 42a → balance tank 2.

Further, the control device 38 uses the heating temperature sensor 3
3 and the temperature detected by the heat retention temperature sensor 34 are 8
Steam heating device 6 and steam insulation device 1 so that the temperature becomes 5 ° C.
Control the amount of steam supplied from No. 3. Then, when these temperatures reach 85 ° C. at time t ₂ and the sterilization period n ₃ is set, the control device 38 activates the timer 35, and the preset time T ₁ ( Time measurement is started for 30 minutes) and the subsequent time T ₂ (10 minutes). At the same time, the control device 38 causes the display unit 3 to
6 is activated to display the light and inform that the sterilization is in progress.

Next, as shown in FIG. 3, when the time T ₁ is measured at the time t ₃ , the first air purge period n ₄ starts from the time t ₃ . In response to the end of this timing, the control device 38 stops the display unit 36 and switches the air purge switching valve 16 and the unit inlet switching valve 17. At this time, the manual valve 23b is switched.

As a result, as shown in FIG. 6, the water flows through the balance tank 2 → sanitary pump 3 → flow passage 4a → homogenizer 11 → each flow passage 4b, 4c → return path 42c and is discharged from the manual valve 23b. It Also, from the air clean unit 43 to the air purge switching valve 1
Air enters the flow passage 4b of the holding unit 12 via 6 and water is expelled from the flow passage 4b.

On the other hand, the controller 38 controls the heating temperature sensor 3
3 and the temperature detected by the heat retention temperature sensor 34 are 6
The supply amount of steam from the steam heating device 6 and the steam heat insulating device 13 is controlled so as to decrease to 5 ° C.

Next, as shown in FIG. 3, when the time T ₂ is measured at the time t ₄ , the second air purge period n ₅ starts from the time t ₄ . In response to the end of this timing, the control device 38 temporarily activates the display unit 36 and the chime 37 to cause the lamp display and the chime sound to be emitted. Further, the controller 38 opens the drain valve 21 to stop the vane pump 14.

From the drain valve 21, the water remaining in the flow passage 4b of the holding unit 12 is drained as shown in FIG. However, after the vane pump 14, water remains in the flow passage 4e and the return passage 42a.

In this state, since the drainage from the manual valve 23b is continued, the water in the balance tank 2 continues to decrease.

At time t ₅ shown in FIG. 3, the balance tank 2
When the amount of water in the milk is sufficiently reduced, the milk is sent to the balance tank 2 through the multi-plate 1 and the milk is replenished.

After this, look inside the flow passage 4c through the side glass 24a immediately in front of the holding unit 12, and after confirming that milk has flowed to this portion,
The operation panel 31 is operated to instruct the start of the first holding period n ₆ . In response to this, the control device 38 controls the air purge switching valve 16 and the unit inlet switching valve 17
Switch. Further, the control device 38 activates the timer 35 and causes the timer 35 to start measuring the time T ₃ (35 minutes) set in advance.

In this state, the milk is, as shown in FIG. 8, the balance tank 2 → sanitary pump 3 → flow passage 4a →
Homogenizer 11 → flow paths 4b, 4c, 4d flow, and the water preceding the milk is drained from drain valve 21.

During this first holding period n ₆ ,
Milk fills the flow passage 4b of the holding unit 12 and reaches the drain valve 21. At this time, the concentration sensor 32 detects that milk has flowed in the vicinity of the drain valve 21. In response to the detection output of the concentration sensor 32, the control device 38 switches the drain valve 21 and closes the unit outlet valve 19 once. As a result, until the end of the first holding period n ₆ ,
The first milk will remain in the holding unit 12, and this first milk will be sterilized by keeping it at 65 ° C. for 30 minutes.

Further, the air remaining in the flow passage 4b of the holding unit 12 reaches the manual valve 23b through the return path 42b together with milk and is discharged from the manual valve 23b.

Further, this first holding period n ₆
At the end of, the control device 38 activates the groundwater pumping device 8 and the chilled water cooling device 9 to circulate the groundwater and the chilled water between the groundwater pumping device 8 and the chilled water cooling device 9 and the heat exchanger 5. .

As shown in FIG. 3, the time T ₃ is measured at time t.
_When it ends at ₆ , the second holding period n ₇ starts from this time t ₆ . In response to the end of this timing, the control device 38 temporarily activates the display unit 36 and the chime 37 to emit a lamp display and a chime sound to notify that the milk sterilization process has started. To do.

Further, the control device 38 closes the CIP valve 18, opens the unit outlet valve 19, restarts the vane pump 14, and operates the vane pump 14 at a low speed. As a result, as shown in FIG. 9, the milk is balanced tank 2 → sanitary pump 3 → flow passage 4a → homogenizer 11 → each flow passage 4b, 4c, 4d, 4e, 4f.
→ The water that flows through the return path 42a and precedes the milk is discharged from the manual valve 23b.

At this time, the side glass 24h in the vicinity of the surge tank 15 is checked, and it is confirmed that milk has flowed to this portion, and then the manual valve 23g is switched. As a result, the milk is stored in the surge tank 1 as shown in FIG.
It flows into 5, and is stored here.

During the second holding period n ₇ , the vane pump 14 is operated at a low speed, so that milk is mixed in the flow passage 4b of the holding unit 12 for 3 times.
It takes 0 minutes to flow and is kept at 65 ° C. for pasteurization. After that, the milk passes through the ground water cooling section 5c and the chilled water cooling section 5d of the heat exchanger 5 at 5 ° C.
After being cooled to a certain degree, it is guided to the surge tank 15.

Here, the milk is heated at a low temperature while gradually flowing through the flow passage 4b of the holding unit 12 at a constant speed. As a result, the milk is heated without spots, and milk of constant quality can be obtained.

The milk sterilization process is continued as long as the milk remains in the balance tank 2. When the milk in the balance tank 2 is low, the faucet 41 is operated to add water.

After this, the inside of the flow passage 4c is checked through the side glass 24a immediately before the holding unit 12, and when water flows into this portion, a time point t ₇ shown in FIG.
The operation panel 31 is operated to instruct the end of the milk sterilization process and the start of the third air purge period n ₈ . In response to this, the control device 38 causes the air purge switching valve 16 to
And the unit inlet switching valve 17 is switched to the CIP valve 1
Open eight. Further, the control device 38 activates the timer 35 to set a preset time T ₄ by the timer 35.
Start timing (10 minutes).

As a result, as shown in FIG. 11, air enters the flow passage 4b of the holding unit 12 from the clean air unit 43 through the air purge switching valve 16, and the milk is expelled from the flow passage 4b.

Next, as shown in FIG. 3, when the time T ₄ is measured at time t ₈ , the fourth air purge period n ₉ starts from this time t ₈ . In response to the end of this timing, the control device 38 temporarily activates the display unit 36 and the chime 37 to cause the lamp display and the chime sound to be emitted. Further, the control device 38 switches the air purge switching valve 16 and the unit inlet switching valve 17 again, and the CIP valve 18
Close.

As a result, the remaining milk flows again from the flow passage 4e to the surge tank 15 as shown in FIG.
It is stored in this surge tank 15.

At this time, looking at the side glass 24h in the vicinity of the surge tank 15, when the air and water following the milk come in, the manual valve 23g is switched. As a result, water is returned through the return path 42a.

After this, at the time point t ₉ shown in FIG.
1 is operated to instruct to stop the device, the control device 38
Ends the operation of each part and is completed.

After a series of operations for sterilizing milk is completed in this manner, the process for cleaning and sterilizing the sterilizing apparatus is further started.

The cleaning and sterilization of this sterilizer are performed by circulating the wash water and the rinse water. 13, FIG. 14, and FIG. 15 show a wash water supply path, a wash water recovery path, and a rinse water path.

In the wash water supply path of FIG. 13, the wash water is led to each wash water tank 51 → wash water pump 52 → multi-plate 1 → balance tank 2 and is sent from there through the sanitary pump 3. , It returns to the balance tank 2 again through each part.

In the wash water recovery path of FIG. 14, wash water is supplied to each wash water tank 5 through the manual valve 23a.
Set back to 1.

Further, in the rinse water path of FIG. 15, water is introduced from the faucet 41 into the balance tank 2,
It is delivered from the balance tank 2 via the sanitary pump 3 and returned to the balance tank 2 through each part or is drained immediately before being returned to the balance tank 2.

Most of the routes of the washing water and the rinsing water are distribution channels, and unlike the case of washing each holding tank as in the conventional apparatus, the loss of the washing water is small, which is economical. And the time required for cleaning can be shortened. Further, since the wash water reaches every corner of the distribution channel, every corner can be easily washed. Furthermore, since it does not have a holding tank,
The number of valves can be reduced, which is also advantageous for cleaning.

[0075]

[Effect] As described above, according to the sterilizer of the present invention, milk is not stored in the holding tank but is kept warm while being sterilized while flowing in the distribution pipe, so that milk of uniform quality without spots is obtained. be able to.

Further, not having a holding tank as in the conventional apparatus enables easy and quick cleaning.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an embodiment of a milk sterilizing apparatus of the present invention.

FIG. 2 is a block diagram showing a control system of the apparatus of the embodiment shown in FIG.

FIG. 3 is a timing chart used to explain a processing procedure of the apparatus of the embodiment of FIG.

FIG. 4 is a diagram used for explaining a preliminary period in the processing procedure of the apparatus of the embodiment of FIG.

5 is a diagram used for explaining a sterilization preparation period in the processing procedure of the apparatus of the embodiment of FIG.

6 is a diagram used for explaining a first air purge period in the processing procedure of the apparatus of the embodiment of FIG.

FIG. 7 is a diagram used to explain a second air purge period in the processing procedure of the apparatus of the embodiment of FIG.

FIG. 8 is a diagram used for explaining a first holding period in the processing procedure of the apparatus of the embodiment of FIG.

FIG. 9 is a diagram used for explaining a second holding period in the processing procedure of the apparatus of the embodiment of FIG.

FIG. 10 is a second part of the processing procedure of the apparatus of the embodiment of FIG.
Diagram used to explain the holding period

11 is a third flowchart of the processing procedure of the apparatus of the embodiment of FIG.
Diagram used to explain the air purge period

FIG. 12 is a fourth part of the processing procedure of the apparatus of the embodiment of FIG.
Diagram used to explain the air purge period

FIG. 13 is a view used for explaining a supply path of washing water in the apparatus of the embodiment of FIG.

FIG. 14 is a view used to explain a recovery path of wash water in the apparatus of the embodiment of FIG.

FIG. 15 is a diagram used to explain a path of rinsing water in the apparatus of the embodiment of FIG.

FIG. 16 is a diagram illustrating a conventional sterilizer.

[Explanation of symbols]

 1 multi-plate 2 balance tank 3 sanitary pump 4a, 4b, 4c, 4d, 4e, 4f flow passage 5 heat exchanger 6 steam heating device 7 hot water heating device 8 groundwater pumping device 9 chilled water cooling device 11 homogenizer 12 holding tube unit 13 Steam insulation device 14 Vane pump 15 Surge tank 31 Operation panel 32 Concentration sensor 33 Heating temperature sensor 34 Heating temperature sensor 35 Timer 38 Control device

Claims (2)

[Claims] 1. A balance tank for storing a liquid, a heating means, a heat retaining means, a cooling means, a surge tank for storing a liquid, and a flow pipe from the balance tank to the surge tank through the heating means, the heat retaining means and the cooling means. , A plurality of valves and at least one pump inserted in the middle of the flow pipe, the flow pipe is heated by the heating means, is kept at a predetermined temperature by the heat retention means, is cooled by the cooling means, The pump is a milk sterilizer that pumps the liquid in the balance tank to the surge tank through the flow pipe at a flow rate per unit time such that the liquid in the flow pipe spends a predetermined time and passes through the heat retaining means. 2. One of the valves drains the liquid from a part of the flow pipe and the other pumps air into the part of the flow pipe instead of the drained liquid. The milk sterilizer according to claim 1.