JP2808016B2 - Foam spray-drying method, apparatus and method for producing powdered cream - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a spray drying method, in particular, a foam spray drying method, and an apparatus thereof, and a novel method for producing a powder cream using the drying method.

Problems of the prior art Conventionally, powdered creams added to coffee, tea and the like have been produced by hot air spray drying, freeze drying and the like. The spray drying method is a drying method which is short in drying time and suitable for mass processing. The powder cream produced by the conventional method has insufficient dispersibility and solubility, and tends to settle and precipitate when added to coffee or the like, and, like sugar, is completely dispersed and dissolved unless stirred with a spoon. do not do. In contrast, when added to coffee or the like, fresh cream spreads on the liquid surface to form a thin film, and then gradually settles and diffuses throughout. This difference was a drawback of the powdered cream. In addition, some powder cream products have a problem that oil-off occurs after dissolution.

To remedy this, it has been proposed to increase the porosity of the powdered cream particles using a foam spray drying method. 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 can control various physical properties and quality such as specific volume, sedimentation property and solubility of the resulting dried product, but also can enhance the drying effect of the product, and can be used widely. It is worthwhile (JP-A-59-196701).

As a specific example of the foam drying method, there is a method in which a gas is mixed with a raw material liquid and freeze-dried to adjust the sedimentability of the dried product to give a new added value to the product (Japanese Patent Laid-Open No.
55-37119) and a method of obtaining the same effect by adjusting the solubility of a dried product by vacuum-drying a gas-dispersed raw material (JP-A-59-183649).

In the conventional foam spray drying method and its apparatus, as shown in FIG. 6, a drying tower 4, a spray nozzle disposed therein, and a raw material are supplied to the nozzle as in a general pressure spray type spray drying apparatus. And a high-pressure pump 1 for pressure feeding. As the arrangement of the gas mixing section for blowing gas into the raw material liquid, two types shown in FIGS. 6 and 7 are known. In these figures, 1 is a high-pressure pump, 2 is a high-pressure compressor, 3
Denotes a pressure reducing valve, 4 denotes a spray-drying tower, 17 denotes a raw material liquid tank, 18 denotes a liquid feed pump, 20 denotes a pressurized gas supply source, and 23 denotes a gas flow control valve.

More specifically, in the arrangement shown in FIG. 6 (JP-A-59-196701), the gas mixing portion is disposed in a high-pressure pipe between the high-pressure pump and the nozzle, and FIG. Showa 50-
No. 26628), the gas mixing part is a high pressure pump 1
Is arranged on the inflow side or the upstream side of the pipe, that is, on the low pressure pipe.

These arrangements have advantages and disadvantages. The former (FIG. 6) has the advantage that the gas can be mixed almost indefinitely in the practical range and the physical properties of the dried product can be largely adjusted. In order to prevent the liquid from flowing backward, it was necessary to constantly increase the gas pressure above the internal pressure of the high pressure pipe. Therefore, this arrangement requires additional equipment such as a high-pressure compressor 2, a gas flow control valve 23 capable of withstanding high pressure, a pressure reducing valve 3, a check valve (not shown), and not only increases the initial cost of the apparatus, This leads to an increase in maintenance costs for maintenance and inspection of the incidental facilities, and furthermore, there is a danger of a backflow of the raw material liquid to the gas supply pipe when the gas pressure drops due to any failure. There have been major problems in terms of handling safety (especially against explosion of compressible gas) and stability, such as an increase in failure frequency and a decrease in reliability of stable operation for a long time due to the increase.

The latter arrangement (FIG. 7) is advantageous with respect to the disadvantages of the arrangement of FIG. 6, since the gas mixing section is arranged in the low-pressure pipe. However, although this arrangement is suitable for processing small samples experimentally or for a short time, the ratio of the flow rate of the mixed gas to the flow rate of the raw material liquid is limited (approximately 2.5%). Pulsation occurs in the ejection flow rate and spray pressure of the raw material liquid ejected from the nozzle,
There have been problems that spray drying cannot be performed stably over a long period of time, knocking and noise are generated, and the durability of the high-pressure pump and its peripheral devices is reduced. Therefore, the latter arrangement was very rarely used in factory mass production. In addition, the arrangement of FIG. 7 is limited to the control of various physical properties of the product due to the limitation of the flow rate ratio of the mixed gas, so that it has reached the point of completion as a foam spray drying method and apparatus on an industrial scale. Did not.

In the first place, when the gas mixing part is arranged in the low pressure pipe portion on the upstream side of the high pressure pump, the reason why stable production becomes difficult when the amount of the blown gas becomes large is that the fluid becomes a gas-liquid multiphase flow. This problem is particularly caused when the standard state equivalent volume flow rate of the injected gas is 2.
It becomes remarkable when it exceeds 5%.

Problems that occur when a gas-liquid multiphase flow is caused to flow through a high-pressure pump are as follows.

As compared with the case where only the raw material liquid is flown (when gas is not blown), the quantitativeness of the discharge amount of the high-pressure pump is broken, the discharge amount is reduced, and the spray pressure is reduced.

The discharge of the high-pressure pump and the pulsation of the spray pressure are increased, knocking and abnormal noise are generated, and the high-pressure pump and peripheral devices are damaged or the durability of the devices is reduced.

Therefore, a foam spray-drying method which has solved all the above-mentioned problems has not yet been realized.

The present invention allows a large amount of gas to be blown by arranging a gas mixing section in the low-pressure pipe portion on the upstream side of the high-pressure pump,
Prevent or reduce the above-mentioned adverse effects, and at the same time greatly expand the control limits of various physical properties of the dried product,
A foam spray-drying method capable of drying in an extremely stable state, an apparatus for performing the method, and a novel powder cream which solves the above-mentioned problems of the conventional powder cream by applying the method. It is intended to provide a manufacturing method.

Means for Solving the Problems The present inventors conducted a spray experiment using the experimental apparatus shown in FIG. 8 to simulate the existing foam spray drying method using water and air as the raw material liquid and gas, respectively. Then, the following findings were obtained.

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

a) In general, when a gas-liquid multiphase flow is supplied to a plunger pump, the degree of decrease in the discharge amount of the liquid phase linearly correlates with the volume flow rate ratio of the gas phase to the liquid phase at the inlet of the pump.

b) Similarly, the amplitude of the discharge pressure oscillation of the pump is linearly correlated with the above volume flow rate ratio. At this time, a centrifugal pump is installed at the pump inlet to disperse and disperse bubbles by the stirring action. In this case, a certain amount of vibration reduction effect can be obtained regardless of the volume flow rate ratio.

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

(A) A means for increasing the internal pressure of the raw material liquid pipe on the upstream side of the high pressure pump is newly added.

(A) A means for dispersing the gas flowing into the inlet of the raw material liquid of the high-pressure pump as fine bubbles in the raw material liquid is newly added.

The above (A) is that the volume flow ratio of the gas phase to the liquid phase (the volume flow ratio under actual pressure conditions) is reduced, and (A) is that the behavior of the multiphase flow is a single liquid due to the dispersion of the gas phase. The flow approaches the state of a phase flow (a liquid phase having a relatively large compression ratio), which is effective in avoiding the above-mentioned adverse effects.

Regarding the above (A), even in a conventional ordinary production line, since the raw material liquid arrangement has a certain degree of internal pressure, when the amount of blown gas is small, the above-mentioned adverse effects are hardly observed. . Although it depends on various factors such as the physical properties of the raw material liquid and the operating conditions, when the volume flow rate of the blown gas in terms of standard state generally exceeds 2.5% (volume, the same applies hereinafter) of the raw material liquid volume flow, the adverse effects of the preceding paragraph are significant. Become. In the first place, since the above-mentioned problem is caused by a gas-liquid mixed phase, even if a gas is present in the raw material liquid as a dispersed phase, if a homogeneous and extremely fine dispersed state or dissolved state can be created, the gas is no longer dispersed. The raw material behaves not as a gas-liquid mixed phase but as a single liquid phase of a compressible liquid, and the above-mentioned problem does not occur. However, properties such as the viscosity and surface tension of the raw material liquid to be actually treated, the particle size of gas particles contained in the raw material liquid, and properties and density such as affinity with the raw material liquid are involved. Such an ideal dispersion or dissolution state is not practically feasible.

The present inventors, based on the above findings, when blowing gas into the raw material liquid, while minimizing the bubbles as much as possible, further pressurized, to bring the foamed raw material closer to the ideal state, in fact the above-mentioned Reached to overcome the problem.

That is, in the present invention, in a foam spray drying method 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, the gas flow rate is converted to a standard state volume by 2.5% of the raw material liquid flow rate. The gas is blown into the raw material liquid at a flow rate exceeding the above, and the gas is made into fine bubbles to be uniformly dispersed, and the pressure on the upstream side of the high-pressure pump is increased. As a result, gas can be mixed into the raw material liquid in a practically practical range in a desired mixing amount without any limitation.

Applying the above method to the production of a powder cream, that is, in the above method, the raw material liquid is concentrated milk for powder cream, and the blown gas is selected from the group consisting of air, inert gas, carbon dioxide gas, and nitrogen gas. By using at least one type of gas, it exhibits dispersibility and solubility close to that of a fresh cream, does not cause oil-off after dissolution, and has a high degree of dryness (less moisture)
The product is obtained.

Further, in a foam spray drying apparatus in which the raw material liquid into which the gas has been blown is pumped by a high-pressure pump and sprayed from a spray nozzle, means for finely bubbling the gas upstream of the high-pressure pump and uniformly dispersing the gas into the raw material liquid are provided. The above method can be performed by providing a pressure increasing means for increasing the pressure of the flow path on the upstream side of the high pressure pump.

In this case, the means for forming gas into fine bubbles upstream of the high-pressure pump and uniformly dispersing the gas in the raw material liquid is a porous member arranged in the raw material liquid flow path on the upstream side of the high-pressure pump. And that the porous member is disposed in the raw material liquid flow path having a reduced diameter.

In the method and the apparatus of the present invention, the raw material liquid is not limited, and can be applied to any raw material liquid such as a dairy product concentrated solution, an inorganic or organic solution, a suspension, and an emulsion.

In the method and the apparatus of the present invention, the gas used is particularly effective when a gas which is hardly dissolved in the raw material liquid such as nitrogen gas or air is used. However, in the case where the above-mentioned adverse effects occur, the improvement effect can naturally be expected. Also,
The gas may be finely dispersed in the raw material liquid in a gas state, and may be a liquefied gas when blown. Blowing in a liquefied gas state or a pressurized state also serves as a means for increasing pressure.

The high-pressure pump for pressure-feeding the raw material in which the gas is finely dispersed to the spray nozzle may be of any type, such as a plunger type, a gear type, and a piston type.

As a means for miniaturizing the gas to be blown, for example, a mechanical device such as a sharing pump having a rotating stirring means may be provided in a pipe through which the gas-liquid multiphase fluid flows. As described above, it is desirable to use a static mechanism in which a gas is finely blown from the surface of a cylindrical member formed of a porous material into a flow of a liquid.
In the latter type, the raw material liquid is introduced at high speed in a spiral or vortex flow along the cylindrical surface so as to shear the gas blown in finely from the cylindrical porous member and blown into finer bubbles. Is desirable. Pressure loss due to flow expansion,
It is desirable to rectify the flow to reduce the probability of vortex and bubble groups coalescing. In addition, the porous member has a number
It may be a material having a thickness of about mm and having a large number of fine pores penetrating between both the inner and outer sides, or a relatively thin film material having a myriad of small holes. It is desirable that the pores or pores are uniformly distributed and as small as possible (eg, 1 μm to 100 μm). Examples of the former include sintered materials and glass fibers manufactured by powder metallurgy, and examples of the latter include punching metal and membranes such as membrane filter materials of cellulose ester and nylon.

The pressurizing means may be of any type. However, if a pressurizing means of a type that generates a swirling flow, a turbulent flow, or a vortex is used in the vicinity of the gas blowing unit, it can be used for forming microbubbles. . The pressure increasing means is disposed on the inflow side or upstream side of the high pressure pump, and there is no limitation on the positional relationship between the pressure increasing means and the gas blowing section. For example, a plurality of centrifugal pumps may be arranged in series in a raw material pipe, and a gas may be blown between the pumps.

Next, the present invention will be described in more detail based on examples of a method for producing a powder cream using the foam spray drying method of the present invention.

Example [Example 1] An existing mixture for powder cream is concentrated to a solid concentration suitable for spray drying (milk solid content 5%), and contains fat at least 20% or more in solid content. , And nitrogen gas was used as the blowing gas. The amount of nitrogen gas blown exceeded 25 ml of nitrogen gas at standard pressure (1 atm) with respect to concentrated milk 1 so that the volumetric flow rate in standard condition exceeded 2.5% of the concentrated milk flow rate. Although the amount is blown, the amount is naturally 25 ml or less under the pressure at the time of blowing.

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

In the conventional apparatus shown in FIG. 9, concentrated milk (solid content: 50%), which is a raw material liquid, is sent from a tank 17 to a high-pressure pump 15 via a heat exchanger 19 by a liquid sending pump 18, and is supplied to a spray nozzle of the drying tower 4. To be pumped. The flow rate of the concentrated milk is adjusted by adjusting the amount of reflux by adjusting the opening of the throttle valve 16.

The gas is blown from the nitrogen gas cylinder 20 through the pressure reducing valve 21, the flow meter 22, and the control valve 23 into the raw material liquid pipe on the downstream side of the high pressure pump 15. The conventional gas-liquid connection pipe shown in FIG. 4 was used for the gas injection section. Arrow in FIG.
29 indicates the direction of flow of the raw material liquid inside the pipe 31 introduced from the opening 30, 32 indicates a closing plate for fixing the connection port 34 of the gas supply pipe 33, and the closing plate 32 is detachable by a union 35. Fixed.

The apparatus of the present invention shown in FIG. 1 is a modified version of the apparatus shown in FIG. 9, and is a centrifugal pump 25 (head 18 m) as a pressure increasing means.
Is disposed between the gas blowing unit 24 and the high-pressure pump 15. In this embodiment, the stirring effect of the centrifugal pump is
It is also used as a means to reduce air bubbles. In this embodiment, the members shown in FIG. 5 were used for the gas blowing section 24. In FIG. 5, the arrow 36 indicates the direction of flow of the raw material liquid introduced through the opening 37 inside the pipe 38, and 39 is introduced through the gas supply pipe 41 and the connection port 40 fixed to the closing plate 47. This is a gas injection conduit. One end of the conduit 39 is connected to a cylindrical small-diameter porous member 42 arranged coaxially with the tube 38. Reference numeral 43 denotes a rectifier that prevents the microbubbles blown from the porous member 42 from reuniting due to a vortex. A union 44 detachably mounts the entire unit including the gas blowing conduit 39. The raw material liquid is introduced in a direction perpendicular to the gas injection conduit arranged linearly, and the liquid flow is accelerated by the reduced diameter portion 45, and bubbles generated from the surface of the cylindrical porous member are:
It can be sheared and shredded by the accelerated liquid stream to produce very fine bubbles. 46 is an enlarged diameter portion.

The production conditions of powdered cream and the water content and specific volume of the product in both devices are shown in Table 1. In Table 1, column A shows the data of the comparative example using the conventional device shown in FIG. The data of the example using the apparatus of the present invention shown in the figure are respectively shown.

In the case of A, even if the gas flow rate was 25 Nl / h, the high-pressure pump during the production was pulsated so strongly that it could not be operated for a long time. In the case of B, even if the gas flow rate was 100 Nl / h, the same stable production as usual could be performed.

The physical properties of the dried powder are 3.4% when the moisture content is A and 2.7% when the moisture content is B. The drying effect is remarkably improved by increasing the gas amount. The specific volume is 1.
It was 68 ml / g, and in the case of B it was 2.10 ml / g (both were measured by the impact method), and the specific volume of the product could be controlled more widely by increasing the gas flow rate.

Example 2 In this example, an apparatus in which a booster was added to the apparatus shown in FIG. 1 was used. More specifically, as shown in FIG. 2, by connecting a metering pump 26 and a regulating valve 27 in parallel between the heat exchanger 19 and the gas blowing section 24 of the apparatus shown in FIG. , Ie, the pressure of the gas injection section, can be adjusted.

Except for the heat exchanger outlet pressure, gas injection unit pressure, high pressure pump inlet pressure, and high pressure pump discharge pressure shown in Table 2,
Powdered milk was produced under the same production conditions as in Example 1.

In Table 2, column A shows the data of the comparative example using the conventional apparatus shown in FIG. 9, and column C shows the data of the example using the apparatus of the present invention shown in FIG.

In the case of A, the inlet pressure of the high-pressure pump was 0.7 kg / cm ² (gauge), but in the case of C, it became 9.0 kg / cm ² (gauge). The discharge pressure did not decrease, and the device could be manufactured in an extremely stable state.

The solubility of the obtained milk powder was measured by the ADMI (American Milk Milk Association) centrifugation method.
In the case of C, the value was about 0.01 ml, and the solubility of the dried product could be remarkably improved by the method of the present invention.

Example 3 In this example, the apparatus of the present invention shown in FIG. 3 was used. More specifically, in the apparatus shown in FIG. 3, the pressure raising mechanism and the bubble miniaturization mechanism are separated to some extent. That is, in FIG. 1 (Embodiment 1) and FIG. 2 (Embodiment 2), one centrifugal pump serves both as a pressure raising means and a bubble miniaturization means, but in the apparatus of this embodiment, A metering pump 26 is provided on the upstream side of the gas injection unit 24 and is used as a pressure increasing means, and a sharing device (Ebara Milder MDN-30) is used.
6) 28 is provided between the high-pressure pump 15 and the gas blowing unit 24, and is used as one of the bubble miniaturization means.

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

(Preparation of concentrated milk) In a 2000-volume stirred tank with a steam jacket,
222.5 kg of water at 50 ° C and 27.5 kg of sodium caseinate were added, and the mixture was heated to 70 ° C and dissolved. A melt obtained by melting 5 kg of lecithin in 175 kg of palm oil was mixed with the above solution, and then 100 kg of corn syrup, 175 kg of edible lactose, 80 kg of a 10% dipotassium phosphate solution, and 550 kg of water were added, and the mixture was maintained at 70 ° C. Stir and dissolve. The obtained solution is subjected to a homogeneous pressure of 150 kg / cm ² ,
The mixture was put in a homogenizer at a temperature of 70 ° C., further sterilized by holding it at 85 ° C. for 10 minutes in a tank equipped with a steam jacket, and concentrated by an evaporator under reduced pressure until the total solid content became 50%.

(Manufacturing conditions and nitrogen gas flow rate) The high pressure pump inlet pressure is 9.0 kg / cm ² and the high pressure pump discharge pressure is 150 kg / cm ^2. Perform foam spray drying in 8 stages, and 8 kinds of powder cream 450k
g (total amount) was obtained.

(Properties of powdered cream) Add 2 g of each of the obtained 8 types of samples (A to H) to 100 ml of 1.5% concentration instant coffee at normal drinking temperatures of 50 ° C, 60 ° C, 70 ° C, and 80 ° C. The dissolution state at the time of carrying out was visually observed.

The specific volume of the powdered cream was determined by taking 50 g of each sample in a 30 ml test tube with a 0.1 ml scale, and tapping 200 times with an Ishiyama-type specific volume tester (Ishiyama Chemical Instruments Co., Ltd.) at a height of 4 cm and a tapping volume of 200 times. Was divided by the weight.

The free fat content (%) was determined as follows. That is, 3 g of each sample was placed in a test tube with a stopper having a diameter of 2 cm and a flow of 18 cm, and 20 ml of petroleum ether having a boiling point of 10 to 60 ° C. was added, shaken at room temperature for 20 minutes, vacuum-filtered, and the fat Weigh and
The ratio (%) of the extracted fat amount to the total fat was calculated.

Oil off is 100% 1.5% coffee liquid at 70 ℃.
2 g of each sample was added to each ml, and after complete dissolution, the presence or absence of oil-off was visually observed.

 Table 3 shows the above results.

Regarding the dissolution state, the powder cream (sample A) into which nitrogen gas was not blown only settled at any dissolution temperature, but nitrogen gas was added to 1 kg of solid content.
Samples B to H blown at a rate of ~ 1400ml (2.5-70% by volume flow rate), the liquid surface becomes cloudy at any dissolution temperature, spontaneously settles, and the dissolution state is similar to that when fresh cream is added. Indicated. In particular, it is known that the formation of a cloudy film on the liquid surface is very similar to that when fresh cream is added, since the volume flow rate ratio exceeds about 5%. Also, the higher the melting temperature, the closer to the dissolved state of the cream. This seems to be due to the relatively high dissolution rate (good solubility) relative to the sedimentation rate and the fast dissipation of nitrogen gas.

It is known that the free fat content is hardly affected by the blowing of nitrogen gas, so that Samples B to H do not cause oil-off similarly to Sample A. This is because nitrogen gas was finely blown
This is probably because even if a large amount of nitrogen gas is blown, the powder particles are not destroyed.

Therefore, a powder cream exhibiting a dissolved state similar to a fresh cream can be produced by the foam spray drying method and the apparatus thereof of the present invention.

The foam spray drying method and the apparatus of the present invention and the method for producing the powder cream of the present invention have been described in detail through the examples. However, the present invention is not limited to only the above-described examples, and the technology of the present invention is not limited thereto. Various modifications are possible without departing from the spirit.

For example, in the foam spray drying method, the raw material liquid is not limited to concentrated milk, and can be widely applied to organic and inorganic solutions, suspensions, emulsions, and the like. It will also be appreciated that the volume flow ratio of the feed liquid to the gas is inversely related to the increase in gas pressure, so that an increase in gas injection can be accommodated by a corresponding increase in gas pressure.

In the apparatus of the present invention, a plurality of pressurizing means can be provided. In this case, the arrangement relation between the gas blowing section and the pressurizing means is not limited as long as they are arranged on the upstream side (inflow side) of the high-pressure pump. It may be.

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

Effects of the Invention The effects of the present invention are as follows.

(1) When gas is blown in on the inflow side (upstream side) of a high-pressure pump, there is no reduction in flow rate or knocking, and the limit gas flow rate that can be manufactured in a stable state generally depends on the physical properties and operation of the raw material liquid. It is determined by various factors such as conditions,
In any case, according to the method of the present invention, a larger amount of gas can be blown, so that various physical properties and qualities such as specific volume and solubility of the product are largely controlled.

(2) In the foam spray-drying device, means for making gas into fine bubbles and dispersing them uniformly in the raw material liquid in the low-pressure piping section on the inflow side (upstream side) of the high-pressure pump, and increasing the pressure in the flow path on the upstream side of the high-pressure pump By arranging the means for performing the above, the equipment cost can be reduced, the drying treatment can be stably performed over a long time, and the industrial application range of the foam spray drying method can be expanded.

(3) In the foam spray drying apparatus, it is possible to generate extremely fine bubbles by either disposing a porous member in the gas blowing section or reducing the diameter of the raw material liquid flow path at that time. In addition, since the drying process can be performed more stably for a long time, the industrial application range of the foam spray drying method can be expanded.

(4) The method for producing a powder cream of the present invention enables the production of a powder cream having excellent solubility and properties substantially equivalent to those of a fresh cream.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a foam spray-drying device according to one 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. FIG. 4 is a schematic sectional view of a conventional gas-liquid connecting pipe, FIG. 5 is a schematic sectional view of a gas-liquid connecting pipe 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 of an experimental device simulating the conventional foam spray drying device. FIG. 9 is a layout diagram of a conventional foam spray drying apparatus. DESCRIPTION OF SIGNS 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 regulating valve, 8: Water flow meter, 9: Air flow control valve, 1
0: air flow meter, 11: pressure reducing valve, 12: pressure gauge for plunger pump inlet, 13: pressure gauge for plunger pump discharge pressure (also used for vibration measurement), 14: recorder, 15: plunger high pressure pump, 16 : Flow control valve, 17: raw material tank, 18: liquid feed pump, 19: heat exchanger, 20: nitrogen gas cylinder, 21: pressure reducing valve, 2
2: gas flow meter, 23: gas flow control valve, 24: gas blowing section,
25: pressurized stirring centrifugal pump, 26: metering pump, 27: metering pump outlet pressure control valve, 28: stirring-only sharing device, 29: arrow indicating raw material liquid flow, 30: raw material liquid supply port, 31: pipe,
32: closing plate, 33: gas supply port, 34: connection port, 35: union,
36: Arrow indicating raw material liquid flow, 37: Raw material liquid supply port, 3
8: pipe, 39: gas injection pipe, 40: connection port, 41: gas supply port, 42: porous member, 43: rectifier, 44: union, 45: reduction section, 46: expansion section, 47: closed Board.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigeru Urata 5-1-1 Higashihara, Zama City, Kanagawa Prefecture 508 of Sagamino 15 (72) Inventor Narutori Ando 118, Minami-Kyogaoka, Asahi-ku, Yokohama, Kanagawa Prefecture References JP-A-48-75757 (JP, A) JP-A-49-86935 (JP, A) JP-A-50-105859 (JP, A) JP-A-62-257601 (JP, A) JP-A-55 -37119 (JP, A) JP-A-59-183649 (JP, A) JP-A-59-196701 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) A23C 11/00 B01D 1/16-1/20

Claims (5)

(57) [Claims] In a foam spray-drying method in which a raw material liquid into which a gas has been blown is pumped by a high-pressure pump and sprayed from a spray nozzle, a flow rate of the gas converted to a standard state volume is 2.5% (volume) of a flow rate of the raw material liquid. A) spraying a gas into the raw material liquid at a flow rate exceeding the above), forming fine bubbles to uniformly disperse the gas, and further increasing the pressure in the flow path on the upstream side of the high-pressure pump. 2. The raw material liquid is concentrated milk for powdered cream, and the blown gas is air, inert gas, carbon dioxide gas,
A novel method for producing a powder cream, characterized in that it is at least one gas selected from the group consisting of nitrogen gas, which is spray-dried by the foam spray-drying method according to claim 1. 3. A foam spray-drying apparatus for feeding a raw material liquid into which gas has been blown in by a high-pressure pump and spraying it from a spray nozzle, wherein the gas is made into fine bubbles upstream of the high-pressure pump and uniformly dispersed in the raw material liquid. A foam spray-drying device, comprising: a pressure increasing means for increasing the pressure of the flow path on the upstream side of the high-pressure pump. 4. The method according to claim 1, wherein the means for forming gas into fine bubbles upstream of the high-pressure pump and uniformly dispersing the gas into the raw material liquid is a porous member disposed in the raw material liquid flow path on the upstream side of the high-pressure pump. The foam spray-drying device according to claim 3, characterized in that: 5. A foam spray-drying apparatus according to claim 4, wherein said porous member is disposed in a raw material liquid flow path having a reduced diameter.