JPH0365136A - Foaming and spray-drying process, apparatus therefor and production of powdery cream - Google Patents

Abstract

PURPOSE:To stably perform foaming and spray-drying of a liquid over a long period with a low-cost apparatus by blowing a gas to a low-pressure piping of an inlet side (upstream side) of a high-pressure pump. CONSTITUTION:A liquid raw material to which a gas is blown (e.g. concentrated milk for powdery cream) is transferred with a high pressure pump, sprayed through a spray nozzle and subjected to foaming and spray-drying in the following manner. A gas composed of air, an inert gas, N2 gas, etc., is blown into the liquid raw material at a flow rate exceeding 2.5% of the flow rate of the liquid raw material in terms of the volume of the standard state. The liquid raw material is foamed into fine bubbles and uniformly dispersed and, at the same time, the pressure in the channel at the upstream-side of the high-pressure pump is increased. The gas can be mixed into the liquid raw material essentially without limitation of the mixing ratio within a practical range. The quality and various properties such as specific volume and solubility of the powdery cream prepared by this process can be controlled over wide ranges.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a spray drying method, in particular a foam spray drying method, an apparatus therefor, and a novel method for producing powdered creams using this drying method.

Problems with conventional technology Conventionally, powdered cream added to coffee, tea, etc.
It has been manufactured by hot air spray drying method, freeze drying method, etc. The spray drying method is a drying method that takes a short drying time and is suitable for large-scale processing. Powdered cream produced using conventional methods does not have sufficient dispersibility or solubility, and it settles when added to coffee, etc.

It has a tendency to precipitate, and like sugar, it will not be completely dispersed or dissolved unless stirred with a spoon. In contrast, when fresh cream is added to coffee or the like, it spreads on the liquid surface to form a thin film, and then gradually settles and diffuses throughout. This difference has been a drawback of powdered creams. Furthermore, some powdered cream products have the problem of causing oil-off after dissolution.

To improve this, it has been proposed to increase the porosity of powder cream particles using foam spray drying methods. In the foam spray drying method, a raw material liquid is mixed with a gas in advance and then dried. The foam spray drying method not only makes it possible to control various physical properties such as specific volume, sedimentation, and solubility, but also improves the drying effect of the product, making it suitable for a wide range of applications. It is valuable (Japanese Unexamined Patent Publication No. 196701/1983).

A specific example of such a foam drying method is a method in which a gas is mixed with a raw material liquid and freeze-dried, thereby adjusting the sedimentation property of the dried product and adding new value to the product (Japanese Patent Laid-Open No.
5-37119), and a method of vacuum drying a raw material in which a gas is dispersed to adjust the solubility of the dried product to obtain a similar effect (Japanese Patent Application Laid-open No. 59-183649).

In the conventional foam spray drying method and its equipment, the sixth
As shown in the figure, like a general pressure spray type spray drying apparatus, it has a drying tower 4, a spray nozzle disposed inside the drying tower 4, and a high-pressure pump 1 for pumping the raw material to the nozzle. Two types of arrangement of the gas mixing section for blowing gas into the raw material liquid are known, as shown in FIGS. 6 and 7. In these figures, l is a high-pressure pump, 2 is a high-pressure compressor, and 3 is a high-pressure pump.
is a pressure reducing valve, 4 is a spray drying tower, 17 is a raw material liquid tank, 18
Reference numeral 20 indicates a liquid feeding pump, 20 indicates a pressurized gas supply source, and 23 indicates a gas flow control valve.

To be more specific, the arrangement shown in FIG.
In JP-A No. 50-26628, the gas mixing part is arranged in the high-pressure piping between the high-pressure pump and the nozzle, and in Fig. It is arranged on the inflow side or upstream side of the pipe, that is, on the low pressure piping.

These arrangements have advantages and disadvantages; the former (Fig. 6) has the advantage that almost unlimited gas can be mixed in within a practical range and the physical properties of the dried product can be greatly adjusted;
In order to prevent backflow of the raw material liquid into the gas supply pipe, it was necessary to constantly increase the gas pressure above the internal pressure of the high-pressure pipe. Therefore, in this arrangement, the high pressure compressor 2. Gas flow control valve 23 that can withstand high pressure. Pressure reducing valve 3. Ancillary equipment such as a check valve (not shown) is required, which not only increases the initial cost of the device, but also increases maintenance costs such as maintenance and inspection of these ancillary equipment. There is a risk of backflow of the raw material liquid into the gas supply pipe when the gas pressure decreases, and there are also concerns regarding its handling, such as an increase in the frequency of failures and a decrease in the reliability of long-term stable operation due to the increase in the number of ancillary equipment. There were major problems in terms of safety (especially against explosions of compressible gas) and stability.

The latter arrangement (FIG. 7) has advantages over the disadvantages of the arrangement according to FIG. 6, since the gas inlet is located in the low-pressure line. However, although this arrangement is suitable for experimentally processing a small amount of sample or for short-time processing, there is a limit to the ratio of the flow rate of the mixed gas to the flow rate of the raw material liquid (approximately 2.5%), and this is not practical. This causes pulsations in the ejection flow rate and spray pressure of the raw material liquid ejected from the spray nozzle,
There were problems such as not being able to stably perform spray drying over a long period of time, causing knocking and noise, and reducing the durability of the high-pressure pump and its peripheral equipment. Therefore, the latter arrangement was extremely rarely used in factory mass production. In addition, the arrangement shown in Figure 7 limits the flow rate ratio of the mixed gas, which limits the range of control over the various physical properties of the product, so the foam spray drying method and equipment on an industrial scale have not yet reached the stage of perfection. There wasn't.

In the first place, the reason why stable production becomes difficult when the amount of blown gas increases when the gas mixing section is disposed in the low-pressure piping section on the upstream side of the high-pressure pump is that the fluid becomes a gas-liquid multiphase flow. This problem is especially true when the standard-state equivalent volumetric flow rate of the blown gas is 2.
It becomes noticeable when it exceeds 5%.

The problems that arise when a gas-liquid multiphase flow is passed through a high-pressure pump are as follows:
It is as follows.

■ Compared to the case where only the raw material liquid is flowed (when no gas is blown), the quantitative nature of the discharge amount of the high-pressure pump is lost, the discharge amount decreases, and the spray pressure decreases.

■ The pulsation of the high-pressure pump discharge amount and spray pressure increases, causing knocking and abnormal noise, which may damage the high-pressure pump and peripheral equipment, or reduce the durability of these equipment.

Therefore, a foam spray drying method that solves all of the above-mentioned problems has not yet been realized.

The present invention enables the injection of a large amount of gas by arranging a gas mixing section in the low-pressure piping section upstream of the high-pressure pump, while preventing or reducing the above-mentioned disadvantages and improving various physical properties of dried products. A foam spray drying method that allows drying to be carried out in an extremely stable state while greatly expanding the control limits of the product, an apparatus for carrying out the method, and a device for implementing the method, which can be applied to the above-mentioned conventional powder cream. The purpose of the present invention is to provide a new method for producing powdered cream that solves the problems described above.

Means for Solving the Problems The present inventors have developed an I! method that imitates the existing foam rIX fog drying method using the experimental apparatus shown in FIG. 8, using water and air as the raw material liquid and gas, respectively. We conducted a JN experiment and obtained the following findings.

In the same figure, 5 is a plunger pump (high pressure pump)
, 6 is a centrifugal pump, 7 is a pressure regulating valve, 8 is a water flow needle, 9
is an air flow control valve, 10 is an air flow meter, 11 is a pressure reducing valve,
12 is a plunger pump inlet pressure gauge, 13 is a plunger pump discharge pressure gauge (also used for vibration measurement), and 14
indicates a recorder, respectively.

a) Generally, when a gas-liquid multiphase flow is caused to flow through a plunger pump, the degree of decrease in the discharge amount of the liquid phase is linearly correlated with the volumetric flow rate ratio of the gas phase to the liquid phase at the inlet of the pump.

b) Similarly, the amplitude of the pump discharge pressure oscillation is linearly correlated with the volumetric flow rate ratio. In this case, a certain amount of vibration reduction effect can be obtained regardless of the volumetric flow rate ratio.

Based on the above knowledge, in the actual foam spray drying method,
It has been found that the object of the present invention can be achieved by taking the following measures.

(a) Add a new means to increase the internal pressure of the raw material liquid piping upstream of the high-pressure pump.

(a) A new means is added to disperse the gas flowing into the raw material liquid inlet of the high-pressure pump into the raw material liquid as fine bubbles.

The above (a) means that the volumetric flow rate ratio of the gas phase to the liquid phase (the volumetric flow rate ratio under actual pressure conditions) becomes smaller, and the above (b) means that the behavior of the multiphase flow is changed to that of a single liquid due to the dispersion of the gas phase. This approaches a state of phase flow (liquid phase having a relatively large compression ratio), which is effective in avoiding the disadvantages of (1) and (2) above.

Regarding (a) above, the raw material liquid piping has a certain amount of internal pressure even in conventional normal production lines, so if the amount of blown gas is small, the above-mentioned adverse effects are hardly seen. . Although it varies depending on various factors such as the physical properties of the raw material liquid and operating conditions, in general, when the standard state equivalent volumetric flow rate of the blown gas exceeds 2.5% (volume, the same applies hereinafter) of the raw material liquid volumetric flow rate, the adverse effects described in the previous section will occur. becomes larger. In the first place, the above-mentioned problem is caused by a gas-liquid mixed phase, so even if gas exists as a dispersed phase in the raw material liquid, if a homogeneous and extremely finely dispersed or dissolved state can be created, the gas will no longer be dispersed. The raw material behaves as a single liquid phase of compressible liquid rather than a gas-liquid mixture, and the above-mentioned problems do not occur.

However, the viscosity of the raw material liquid to be actually processed is 2
Properties such as surface tension, particle size of gas particles contained in the raw material liquid, properties such as affinity with the raw material liquid, and density are involved, but such an ideal dispersion or dissolution state is practically impossible to achieve. It is possible.

Based on the above-mentioned knowledge, the present inventors made the bubbles as fine as possible and further increased the pressure when blowing gas into the raw material liquid, thereby bringing the foamed raw material close to the ideal state. reached to overcome the problem.

That is, in the present invention, in the foam spray drying method in which a raw material liquid into which gas is blown is pumped by a high-pressure pump and sprayed from a spray nozzle, the flow rate of the gas is 2.0 times the flow rate of the raw material liquid in terms of standard state volume. Gas is blown into the raw material liquid at a flow rate exceeding 5%, and the gas is made into fine bubbles to be uniformly dispersed, and the pressure of the flow path upstream of the high-pressure pump is increased. As a result, a desired amount of gas can be mixed into the raw material liquid in a practically unlimited amount within a practical range.

Also, applying the above method to the production of powdered cream,
That is, in the above method, the raw material liquid is concentrated milk for powdered cream, and the blowing gas is at least one type of gas selected from the group consisting of air, inert gas, carbon dioxide gas, and nitrogen gas. It exhibits dispersibility and solubility close to that of 100%, does not cause oil-off after dissolution, and provides a highly dry product (low moisture content).

Furthermore, in a foam spray drying device in which a raw material liquid into which a gas is blown is pumped by a high-pressure pump and sprayed from a spray nozzle, a means for making the gas into fine bubbles and uniformly dispersing it in the raw material liquid on the upstream side of the high-pressure pump; The above method can be carried out by providing a pressure increasing means for increasing the pressure in the flow path on the upstream side of the high pressure pump.

In the method and apparatus of the present invention, there are no limitations on the raw material liquid, and any raw material liquid can be used, including concentrated liquids of dairy products, solutions, suspensions, and emulsions of inorganic or organic substances.

In addition, in the method and apparatus of the present invention, the gas used is particularly effective when using a gas that is difficult to dissolve in the raw material liquid, such as nitrogen gas or air, but soluble gas such as carbon dioxide gas or ammonia gas However, if the above-mentioned disadvantages occur, an improvement effect can naturally be expected. Further, the gas only needs to be finely divided into a gaseous state and dispersed in the raw material liquid, and may be a liquefied gas in the state in which it is blown into the raw material liquid.

Blowing in a liquefied gas state or a pressurized state also serves as a means of increasing the pressure.

Furthermore, the high-pressure pump that pumps the raw material in which gas is finely dispersed to the spray nozzle may be of any type, such as a plunger type, gear type, or piston type.

As a means for atomizing the gas to be blown, for example, a mechanical device such as a shearing pump having a rotating stirring means may be installed in the pipe through which the gas-liquid multiphase fluid flows, but this method is shown in Example 1 below. Thus, a static mechanism is desirable in which finely divided gas is blown into the liquid flow from the surface of a cylindrical member made of a porous material. In the latter type, the raw material liquid is guided at high speed in a spiral or vortex shape along the cylindrical surface so that the gas blown into fine particles from the cylindrical porous member is sheared into further fine bubbles. is desirable. It is desirable to rectify the flow in order to reduce the pressure loss caused by the expansion of the flow, the probability of colliding and coalescing of eddy currents and bubble groups. Moreover, the porous member is several meters long.
The material may be a material having a thickness of about 1.5 m and having many fine pores penetrating between the inner and outer surfaces, or a relatively thin film-like material having numerous small pores. It is desirable that the pores or small pores be uniformly distributed and as small as possible (for example, 1 μm" 10100p. Examples of the former include sintered materials manufactured by powder metallurgy and glass fibers, etc.) Examples of the latter include perforated metal and cellulose ester and nylon membrane filter materials.

The pressure increasing means may be of any type, but if a type of pressure increasing means that produces swirling flow, turbulent flow, or vortex flow is used close to the gas injection part, it can also be used to form microbubbles. . The pressure increase means is arranged on the inflow side or upstream side of the high pressure pump, and there is no restriction on the arrangement relationship between the pressure increase means and the gas blowing section.

For example, a plurality of centrifugal pumps may be arranged in series in a raw material liquid pipe, and gas may be blown between them.

Next, the present invention will be explained in further detail based on an example of the method for producing powder ream using the foam spray drying method of the present invention.

Example [Example 1] An existing mixed liquid for powdered cream is concentrated to a solid content concentration suitable for spray drying (milk solid content: 50%), and contains at least 20% fat in the solid content. was used, and nitrogen gas was used as the blowing gas. The nitrogen gas injection amount is
In order to make the standard state converted volume flow rate exceed 2.5% of the concentrated milk flow rate, the standard pressure (
The force of blowing nitrogen gas (1 atm) in an amount exceeding 25 m12 [, of course, under the pressure at the time of blowing, the amount will be less than 25 m12.

In this example, foam spray drying was carried out using the apparatus shown in FIG. 1 as the apparatus of the present invention and the conventional apparatus shown in FIG. 9 as a control.

In the conventional device shown in Fig. 9, the raw material liquid is concentrated milk (
The liquid (solid content: 50%) is sent from the tank 17 by the liquid sending pump 18 via the heat exchanger 19 to the high-pressure pump I5, and then is sent under pressure to the spray nozzle of the drying tower 4. The flow rate of concentrated milk is adjusted by adjusting the amount of reflux by adjusting the opening degree of the throttle valve 16.

Gas is supplied from a nitrogen gas pump 20 to a pressure reducing valve 21° and a flow meter 2.
2. It is blown into the raw material liquid piping downstream of the high-pressure pump 15 via the control valve 23 . For the gas injection section, the gas-liquid connection piping in the United States shown in Figure 4 was used. In FIG. 4, an arrow 29 indicates the flow direction of the raw material liquid introduced from the opening 30 into the pipe 31, and 32 is a closing plate that fixes the connection port 34 of the gas supply pipe 33.
2 is removably fixed by a union 35.

The device of the present invention shown in FIG. 1 is a modified version of the device shown in FIG.
is arranged between the gas blowing section 24 and the high pressure pump 15. In this embodiment, the stirring effect of the centrifugal pump is also utilized as a means for making bubbles finer. In this embodiment, the gas blowing section 24 used the member shown in FIG. In FIG. 5, an arrow 36 indicates the flow direction of the raw material liquid introduced from the opening 37 inside the tube 38, and 39 indicates the direction of the flow of the raw material liquid introduced through the opening 37, and 39 indicates the flow direction of the gas introduced through the gas supply tube 41 and the contact 040 fixed to the closing plate 47. It is a conduit for blowing. A cylindrical porous member 42 with a small diameter is connected to one end of the conduit 39 and is arranged coaxially with the pipe 38 . Reference numeral 43 denotes a rectifier that prevents the microbubbles blown from the porous member 42 from swirling due to the eddies. 4
4 is a union to which the entire unit including the gas blowing conduit 39 is removably attached. The raw material liquid is introduced perpendicularly to the linearly arranged gas blowing conduit,
Moreover, the liquid flow is accelerated by the reduced diameter portion 45, and the air bubbles generated from the surface of the cylindrical porous member are sheared and torn off by the accelerated liquid flow, producing extremely fine air bubbles. can. 46 is an enlarged diameter portion.

The manufacturing conditions for the powdered cream in the re-apparatus and the water content and specific volume of the product are shown in Table 1. In Table 1, column A shows the data of the control example using the conventional apparatus shown in FIG. 9, and column B shows the data of the control example using the conventional apparatus shown in
Data of examples using the apparatus of the present invention shown in the figures are shown respectively.

In case A, even if the gas flow rate was 25N12/h, the high-pressure pump during production pulsated violently and could not be operated for a long time. In case B, the gas flow rate is 100Nff
/h, stable production was possible, exactly the same as usual.

The physical properties of the dry powder are 3.4% when the moisture content is A and 2.7% when the moisture content is B, and it can be seen that the drying effect is significantly improved by increasing the amount of gas. In addition, the specific volume is 1.68 mQ/g in case of A, and 2.10 mQ/g in case of B.
(All measurements are performed using the impact method.) By increasing the gas flow rate, the specific volume of the product can be more broadly controlled.

[Example 2] In this example, an apparatus in which a pressure increasing means was further added to the apparatus shown in FIG. 1 was used. More specifically, as shown in FIG. 2, the heat exchanger L9 and gas blowing section 24 of the device shown in FIG.
By connecting a metering pump 26 and a regulating valve 27 in parallel between the metering pump 26 and the regulating valve 27, the outlet pressure of the metering pump, that is, the gas blowing section pressure can be adjusted.

Milk powder was produced under all the same production conditions as in Example 1, except that the silent exchanger outlet pressure, gas blowing part pressure, high pressure pump inlet pressure, and high pressure pump discharge pressure are shown in Table 2.

In Table 2, column A shows data for a control example using the conventional device shown in FIG. 9, and column C shows data for an example using the device of the present invention shown in FIG.

If the surface pressure [kg/cm” gauge is 1 A, the high pressure pump inlet pressure is 0.7 kg/am.
” (gauge), but in the case of C it was 9゜0kg/am
' (gauge), and even when gas was blown at 70 ON (2/h), there was no pulsation of the high-pressure pump or a drop in the discharge pressure, and production was possible in an extremely stable state.

When the solubility of the obtained milk powder was measured by ADMI (American Milk Powder Institute) centrifugation method, it was O, 1mα for A, whereas it was about O-0-0l for C, which indicates that the present invention Using this method, we were able to dramatically improve the solubility of the dried product.

[Example 3] In this example, the apparatus of the present invention shown in FIG. 3 was used. Specifically, in the apparatus shown in FIG. 3, the pressure increasing mechanism and the bubble refinement mechanism are separated to some extent. That is, in FIG. 1 (Example 1) and FIG. 2 (Example 2), the - centrifugal pumps served as both the pressure increasing means and the bubble atomization means, but in the apparatus of this example, A metering pump 26 is provided upstream of the gas blowing section 24 and used as a pressure increasing means, and a sharing device (Ebara Milder MDN
-306, ) 28 to the high pressure pump 15 and the gas blowing part 24
It is used as one of the means for making bubbles finer.

Using the above-mentioned apparatus, powdered cream was manufactured using the following concentrated milk for powdered cream as a raw material liquid under the following manufacturing conditions.

(Preparation of concentrated milk) 222.5 kg of water at 50°C and 27.5 kg of sodium caseinate were added to a 200,012 volume stirring tank equipped with a steam jacket, and dissolved by heating to 70°C. 1
A melt of 5 kg of lecithin in 75 kg of palm oil was mixed with the above solution I, and then 100 g of corn syrup was mixed.
kg, edible lactose 175 kg% 10% dipotassium phosphate solution 80 kg.

Then, 550 kg of water was added, and the mixture was stirred and dissolved at 70'O. The obtained solution was heated to a homogeneous pressure of 150 kg/cm
The mixture was passed through a homogenizer at a temperature of 70°C, then sterilized by being held at 85°C for 10 minutes in a steam-jacketed tank, and concentrated under reduced pressure using an evaporator until the total solid content was 50%.

(Manufacturing conditions and nitrogen gas flow rate) The high pressure pump inlet pressure was 9.0 kg/cm" and the high pressure pump discharge pressure was 150 kg/cm2, and the nitrogen gas flow rate was in the range of 0 to 70% of the raw material liquid in terms of standard state flow rate. Foam spray drying was performed in 8 stages to obtain 450 kg (total amount) of 8 types of powdered creams.

(Properties of powdered cream) 2 g of each of the 8 types of samples (A-H) obtained were mixed at the usual drinking temperature of 50°C, 960°, 0.70°, 0.8
100ml of 1.5% instant coffee at 0℃
The state of dissolution when added to No. 2 was observed with the naked eye.

In addition, the specific volume of the powdered cream is 0.1 m + 3 on the 2 scale.
0m (50g of each sample was placed in 2 test tubes and tapped 200 times with a vertical width of 4cm using an Ishikawa specific volume tester (Ishikawa Kagaku Kiki Seisakusho), and the apparent amount was determined by dividing the dose by the weight.

Free fat content (%) was determined as follows. That is, each sample was placed in a test tube with a stopper, 2 cm in diameter and 18 cm in length.
Take g and add 20 mQ of petroleum ether with a boiling point of 10 to 60°C.
was added, shaken for 20 minutes at room temperature, vacuum filtered, the fat in the filtrate was weighed, and the ratio (%) of the extracted fat amount to the total fat was calculated.

For oil-off, 2 g of each sample was added to 100 mQ of 1.5% coffee liquid at 70°C, and after complete dissolution, the presence or absence of oil-off was visually observed.

The above results are shown in Table 3.

If you have a problem with melting state 8J, the powdered cream (sample A) that was not blown with nitrogen gas has a melting temperature of -C
However, nitrogen gas is added to 1 kg of solid content at a ratio of 5O-1400r12 (2.5~2.5~1 kg of solid content).
70%) Samples B-H which were injected had a cloudy liquid surface and spontaneous sedimentation at any dissolution temperature, showing a dissolution state similar to that when fresh cream was added. In particular, it can be seen that when the volumetric flow rate exceeds about 5%, the formation of a cloudy white film on the liquid surface becomes extremely similar to that when fresh cream is added. Further, the higher the melting temperature, the closer the melting state is to that of fresh cream. This seems to be due to the fact that the dissolution rate is relatively faster than the sedimentation rate (good solubility) and that nitrogen gas dissipates faster.

It is known that the free fat content is hardly affected by the nitrogen gas blowing, and therefore samples B-H, like sample A, do not suffer from oil-off.

This seems to be because the powder particles are not destroyed even if a large amount of nitrogen gas is blown into the powder because the nitrogen gas is blown into fine particles.

Therefore, by using the foam spray drying method and the apparatus of the present invention, it is possible to produce a powdered cream that exhibits a melting state similar to that of fresh cream.

The foam spray drying method, its apparatus, and the powder cream manufacturing method of the present invention have been described above in detail through Examples, but the present invention is not limited to the above-mentioned Examples, and the technology of the present invention Various modifications are possible without departing from the idea.

For example, in the foam spray drying method, the raw material liquid is not limited to concentrated milk, but also solutions of organic and inorganic substances.

Widely applicable to suspensions, emulsions, etc. It will also be understood that the volumetric flow rate ratio of the raw material liquid and the gas is inversely correlated with the increase in gas pressure, and therefore an increase in the amount of gas blown can be countered by a corresponding increase in the gas pressure.

In the apparatus of the present invention, a plurality of pressure boosting means can be provided, and in this case, the arrangement relationship between the gas blowing part and the pressure boosting means can be changed in any manner as long as they are arranged on the upstream side (inflow side) of the high pressure pump. It's okay to be there.

Furthermore, in the method for producing powdered cream, the composition and concentration of concentrated milk are not limited to the above-mentioned composition and concentration, but can be variously changed within the common sense in conventional powdered cream production.

Effect of the invention The effects of the present invention are as follows.

(1) When blowing gas on the inflow side (upstream side) of a high-pressure pump, the limit gas flow rate that can be produced in a stable state without reducing the flow rate or knocking, etc. is generally determined by the physical properties of the raw material liquid and the operation. Although it is determined by various factors such as conditions, in any case, the method of the present invention allows a larger amount of gas to be injected, and therefore the product's various physical properties such as specific volume and solubility and quality can be significantly improved. controlled by.

(2) In the foam spray drying method, the high pressure pump inlet side (
By locating the gas blowing section in the low-pressure piping section (on the upstream side), equipment costs can be reduced and drying can be carried out stably over a long period of time, expanding the industrial applicability of the foam spray drying method. It could be expanded.

(3) The method for producing powdered cream of the present invention makes it possible to produce powdered cream that exhibits the same solubility as fresh cream.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of a foam spray drying device according to an embodiment of the present invention, FIG. 2 is a layout diagram of a foam spray drying device according to another embodiment of the present invention, and FIG. Furthermore, a layout diagram of a foam spray drying apparatus according to another embodiment; FIG. 4 is a schematic sectional view of a conventional gas-liquid connection piping; FIG. 5 is a schematic sectional view of a gas-liquid connection piping according to the present invention; FIG. 6 is a layout diagram of a conventional foam spray drying device, FIG. 7 is a layout diagram of another conventional foam spray drying device, and FIG. 8 is a layout diagram of an experimental device imitating a conventional foam spray drying device. FIG. 9 is a layout diagram of a conventional foam spray drying device. Explanation of symbols 1: High pressure pump, 2: High pressure compressor, 3: Pressure reducing valve,
4: Drying tower, 5: Plunger pump (high pressure pump),
6: Centrifugal pump, 7: Pressure adjustment valve, 8: Water flow needle, 9:
Air flow control valve, lO: air flow meter, l: pressure reducing valve, 1
2. Pressure gauge for Ni lunger pump, 13. Pressure gauge for Ni lunger pump discharge pressure (also used for vibration measurement), 14:
Recorder, 15 Ni lunge set high pressure pump, 16 Two flow control valves Jl 7: Raw material liquid tank, 18: Liquid feed pump, 19: Heat exchanger, 20: Nitrogen gas cylinder, 21: Pressure reducing valve, 22: Gas flow meter, 23: Gas flow rate control valve, 24:
Gas blowing part, 25: Pressure-boosting stirring centrifugal pump, 26: Metering pump, 27: Metering pump outlet pressure control valve, 28: Sharing device for stirring only, 29: Arrow indicating flow of W feed liquid, 30: *Feed liquid Supply port, 31: Pipe, 32: Closing plate, 3
3: Gas supply port, 34: Connection port, 35: Union, 36
: Arrow indicating flow of raw material liquid, 37: Raw material liquid supply port,
38: Pipe, 39: Gas injection pipe, 40: Connection port, 4
1 gas supply port, 42: porous member, 43: rectifier, 44
2 union, 45: Reducing portion, 46: Expanding portion, 47: Closing plate.

Claims (3)

[Claims] (1) In the foam spray drying method, in which a raw material liquid into which gas is blown is pumped with a high-pressure pump and sprayed from a spray nozzle, the flow rate of the gas converted to the standard state volume is 2.5% (by volume) of the flow rate of the raw material liquid. ) A foam spray drying method characterized in that gas is blown into a raw material liquid at a flow rate exceeding 100%, the gas is made into fine bubbles and uniformly dispersed, and the pressure of the flow path upstream of the high-pressure pump is increased. (2) A claim characterized in that the raw material liquid is concentrated milk for powdered cream, and the blown gas is at least one type of gas selected from the group consisting of air, inert gas, carbon dioxide gas, and nitrogen gas. 1. A novel method for producing a powdered cream, which comprises spray-drying using the foam spray-drying method described in 1. (3) In a foam spray drying device in which a raw material liquid into which gas is blown is pumped by a high-pressure pump and sprayed from a spray nozzle, a means for making the gas into fine bubbles and uniformly dispersing it in the raw material liquid on the upstream side of the high-pressure pump. and a pressure increasing means for increasing the pressure of the flow path on the upstream side of the high pressure pump.