JP3333723B2 - Filter type dust collector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter type dust collector used for producing various kinds of powders such as foods and medicines, and to efficiently remove dust from a powder drying system without lowering the quality. The present invention relates to an apparatus for recovering powder.

[0002]

2. Description of the Related Art Drying methods for drying a liquid substance to obtain a powder product include a freeze drying method and a heating drying method. The apparatuses used for these methods are roughly classified into a cylindrical drying apparatus and a spray drying apparatus. . The equipment to be used varies depending on the product to be manufactured and the amount of production, but from the viewpoint of quality advantages and low-cost mass production, a heated spray-drying apparatus is often adopted. This drying device blows heated clean air into the drying chamber, and ejects liquid substances and their concentrates from the upper part of the drying chamber in the form of a mist with nozzles, rapidly increasing the evaporation area and drying instantaneously. Things. As an example, the temperature of the heated air blown into the drying chamber is about 150 to 170 ° C., and after drying, the temperature of the air drops to about 70 to 80 ° C. when the air is discharged from the drying chamber. The droplets of the liquid material to be sprayed are 10-150 μm, and the water content is 95-98%
It is possible to remove up to. The sprayed liquid material droplets have a small thermal effect due to rapid release of latent heat of vaporization, and have little effect on changes in physical properties. Therefore, the heated spray drying device is suitable for drying protein-containing materials. The spraying method includes
Pressure spray type, two-fluid nozzle type, centrifugal spray type
By appropriately selecting these methods, the particle diameter of the product particles can be adjusted to 40 to 100 μm, 10 to 40 μm, 40 to 80 μm.
μm.

In the production of milk powder or sugar, a solution of milk or sugar is concentrated in a concentration step to form a concentrated solution from which 40 to 90% of water has been removed, which is sprayed from the upper part of a drying chamber and dried. A method for obtaining a powder product is generally used.
It is known that the powder obtained by this method is a hollow particle having a uniform water content, is formed into a spherical shape or a porous shape, and has good solubility. The powder dried in the drying chamber of the heating type spray dryer is discharged out of the drying chamber while being dispersed and mixed in the exhaust air, and is guided to a dust collecting device that separates the powder and air by a duct. .

A device for separating powder contained in air discharged from a drying chamber of a heating type spray drying device has a simple structure because the particle diameter of the powder can be collected in a wide range. , Hygiene, and excellent quality of the recovered powder are required. For this reason, cyclone dust collectors are often used. The cyclone dust collector is
Generally, the upper part is formed in a cylindrical shape and the lower part is formed in an inverted conical shape. However, the exhaust air containing powder is introduced from the side along the inner wall surface at the upper part of the cylindrically formed dust collection chamber. The powder product contained in the exhaust air is swirled in the conical body, and is guided by the centrifugal force to the lower outlet through the inner wall of the cyclone. On the other hand, the air separated from the powder is discharged outside through a duct from the center to the upper part of the dust collection chamber.

[0005] In this case, the recovery rate of the powder is limited to about 98%, although it depends on the performance of the cyclone dust collector.
In the cyclone dust collector, due to its structure, powder having a small particle diameter of 10 μm or less is often discharged as dust to the outside of the cyclone dust collector together with the discharged air.

[0006] The powder having a small particle diameter discharged to the outside without being collected by the cyclone dust collecting apparatus is referred to as a fugitive powder. Equipment was required, and there was little chance of recovering and using the past dust powder due to economical reasons. However, there are problems such as the impact on other equipment and environmental pollution caused by the uncollection of the escaped dust, and various collection measures such as water discharge collection and electric collection are currently being adopted. These collection methods are:
If the dissipated powder is a powder that is difficult to collect and use and must be disposed of, a solution using such a dust collection method is appropriate. However, if the dissipated powder can be recovered and used, a recovery method that allows the recovered powder to be used as a product is desired.

In order to recover and reuse the powder that cannot be separated from the air discharged from the cyclone dust collecting apparatus, it is necessary to provide a separate high-performance collecting facility. There are various types of high-performance collection equipment.
A filter dust collecting device that can collect dust as close as possible to the filter bag by passing air through the filter bag can be expected.

Here, Japanese Patent Application Laid-Open No. 61-222519 discloses a "fluidized bed apparatus provided with a mechanism for detecting a pressure loss of a bag filter". This device is configured to detect clogging of a filter bag provided at an upper exhaust port of a fluidized bed device and perform an operation for preventing a reduction in the performance of the filter bag. In this device, a hole is provided in the body of the fluidized bed to place a measuring device for detecting the pressure loss of the filter bag, and a tube for mounting the measuring device is installed in this hole. An injection nozzle is provided in the pipe so that high-pressure air is blown toward the pipe mouth in order to prevent dust from accumulating at the pipe mouth and hindering measurement.

Japanese Patent Application Laid-Open No. Sho 62-152511, entitled "Local Bag Filter with Enhanced Back-Blow-Off Efficiency" has a structure in which compressed air is blown out as a mechanism for removing dust adhering to the inner surface of the filter bag when separating and discharging the dust. Is disclosed. In this device, in order to prevent an influence on an adjacent filter bag when the filter bag is removed, an uneven plate is interposed between the filter bags to improve the dispensing efficiency.

Japanese Patent Application Laid-Open No. Hei 4-126509 discloses a method for removing harmful acidic components such as soot and dust adhering to a filter cloth of a bag filter and recovering the filtration ability. In this method, high-pressure air is directly sprayed onto the dust adhering surface of the filter cloth to form a crack on the surface of the solidified dust, and the dust is peeled off to remove the dust.

[0011]

In recent years, a technique of collecting powder and treating the collected powder with this filter type dust collector has been adopted. However, the quality of the collected powder has been reduced.
It is difficult to maintain quality for reuse, and the recovered powder is often used for feed. Collected powders such as foods and medicines are used as feed if they do not meet a certain standard, but the quality cannot be maintained because the absolute humidity of the exhaust air from the drying room is as high as 40 to 50 g / kg DA. The powder adheres to the wall of the dust collection chamber of the dust collector and easily accumulates, and there is no air flow inside the adhered and laminated powder, and the side wall of the inner wall is cooled by external air to lower the temperature to reach the dew point. Quality standards for powdered foods, such as dew condensation resulting in microbial contamination, and browning on the surface of the adhered powder due to long-term exposure in an environment at 80 to 90 ° C, resulting in reduced solubility. Due to incompatibility.

As a solution to this problem, a structure is proposed in which powder does not adhere to the inner wall surface of the filter-type dust collecting apparatus, and the shape of the dust collecting chamber has been improved. However, it is impossible to make the interior of the dust collection chamber completely free of dead spaces and joints. The bag filters disclosed in JP-A-62-152511, JP-A-4-126509 and JP-A-61-225519 all have the purpose of restoring the performance of the filter, and are applied to the wall of the dust collection chamber. No consideration has been given to powder adhesion. Moreover,
These known devices have a multi-chamber structure for the continuous collection of dust, or have a complicated internal structure, which completely prevents powder from adhering and laminating to the dust collection chamber wall. In addition to being unable to do this, the equipment itself becomes large and the equipment cost increases. In any case, a powder drying system configured so that the powder collected by the dust collector can be used as a product without deteriorating the quality is conventionally known.

An object of the present invention is to prevent powder from adhering and laminating to the wall of a dust collecting chamber of a filter type dust collecting apparatus, prevent deterioration of powder collected by the filter type dust collecting apparatus, and use the product as a product. It is to provide means that can be used.

[0014]

In order to solve the above problems, according to the present invention, an internal space of a dust collection chamber is partitioned.
The powder-containing air through the filter bag
Dust collector that collects powder contained in air
At the bottom of the dust collection chamber
And a powder on the bottom of the bottom.
Discharge mechanism for discharging is arranged, and the side and bottom of the dust collection chamber
Nozzle that blows compressed gas toward the corner where
It is characterized by having

According to this filter type dust collecting apparatus, the powder adheres to the corner where the side and the bottom of the dust collecting chamber intersect with each other in the dust collecting chamber, where the powder easily adheres, by the removing mechanism. Therefore, the powder can be efficiently prevented from adhering to the wall surface of the dust collection chamber.

As a brushing mechanism for preventing the adhesion of the powder, a structure in which a brush or a brush is provided in the dust collecting chamber can be considered. However, such a mechanism has a high possibility of generating a dead space and is not preferable. In particular, in the case of a brush removing mechanism having a complicated structure such as a brush, there is a possibility that powder adheres to details of equipment constituting the mechanism and becomes contaminated. The compressed gas is
In general, air can be compressed and produced with a compressor or roots blower. However, it is desirable to filter compressed air with a filter and, in some cases, cool it with cooling equipment to prevent contamination of microorganisms and dust. . Nitrogen gas, carbon dioxide gas, or the like may be used as the compressed gas in addition to air, or they may be used in combination with air.

Preferably , the nozzle is fixed or configured to be able to rotate and / or swing. Then, it is possible to prevent a wide range of powder adhesion.

In addition, heated clean air is introduced into the dust collection chamber.
Attach a warming mechanism and heat insulating material outside the bottom.
May be attached. Then, the powder collected in the dust collecting chamber is dropped along the inclined surface without the temperature drop of the inner wall surface,
It can be discharged from the lowermost discharge mechanism. As the discharging mechanism, for example, a mechanism called a rotary valve is suitably used. The rotary valve is a rotary valve in which a plurality of blades capable of shutting off an outlet is operated to rotate around a shaft arranged across the outlet. In addition, the butterfly valves may be provided in two stages and operated one by one. In addition, by installing a heat insulating material on the outside of the inclined surface, the inner wall side of the dust collection chamber is not cooled by external air and dew condensation can be prevented. The powder falls smoothly.

[0019]

[0020]

[0021]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of a powder drying system 1 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a filter type dust collecting device 6 provided in the powder drying system 1.

As shown in FIG. 1, in the powder drying system 1, a cyclone dust collecting device 4 is connected to an exhaust line 3 of a drying device 2, and further, it is connected to an exhaust line 5 of the cyclone dust collecting device 4. The filter type dust collector 6 is connected.

As the drying device 2, a heating type spray drying device is employed. The drying device 2 sprays a liquid substance or a concentrate thereof in a mist form from an upper portion of a drying chamber 12 to which hot air sent from a blower 10 and heated by a heater 11 is supplied, through a liquid supply line 13. In this case, the evaporation area is suddenly increased to instantaneously dry. Blower 10
The amount of air blown is adjusted according to the supply amount of the liquid substance. For example, the amount of air blown to produce 1 kg of powder product is about 20 to 40 kg / h, and 25 kg of powder product per hour is required. If you want to produce
/ H, that is, 630 m ³ / h at room temperature. Heater 1
1, the temperature of the heated air blown into the drying chamber 12 is about 1
It is possible to heat up to around 50-300 ° C. As the heater 11, a large-sized steam-type air heating device using an erofin tube or the like can be used. Alternatively, a heater that burns a fuel such as a combustible gas to heat the air may be used. In that case, it is advisable to remove dust from the air using a filter. Drying chamber 12 through liquid supply line 13
The liquid substance supplied to the inside is, for example, a solution such as milk powder or sugar, or a concentrate thereof. The powder obtained by drying the liquid material and hot air in the drying chamber 12 is dropped in the drying chamber 12 and supplied to the next cyclone dust collector 4 through the exhaust line 3. It is supposed to be.

The cyclone dust collecting device 4 has the above-described exhaust line 3 branched and connected to the upper part of two cyclone dust collecting chambers 15 formed in a cylindrical shape in the illustrated example. The powder and exhaust air produced in the above are introduced from the side along the inner wall surface of each cyclone dust collecting chamber 15 and swirled,
The structure is such that the powder contained in the exhaust air is separated, dropped, and guided to the outlet 16 below the cyclone dust collecting chamber 15. The number of cyclone dust collection chambers 15 to be installed is determined according to the amount of exhaust air, etc., but as shown in FIG.
By providing two cyclone dust collecting chambers 15 and branch-supplying the exhaust air of the drying device 2 respectively, the volume of each cyclone dust collecting device 4 can be reduced, and efficient equipment can be provided.

The outlet 16 at the lower part of each cyclone dust collecting chamber 15
Is connected to a powder transfer line 20. Downstream of the powder transfer line 20 is a secondary cyclone dust collector 2
The exhaust fan 22 is connected to the cyclone dust collecting chamber 1 by suction operation of the exhaust fan 22.
The powder collected in 5 is conveyed through the respective powder outlets 16 in the powder conveying line 20 and collected in the secondary cyclone dust collecting device 21. An upstream side of the transfer line 20 is formed in an air intake port 23 having a filter. In order to prevent the powder from absorbing moisture during transport on the transport line 20 and to change the water content, an intake port 23 is provided with an erofin tube for cooling and dehumidifying the intake air. There is also.

A shifter 25 is connected below the secondary cyclone dust collector 21, and the powder collected from the powder transfer line 20 in the secondary cyclone dust collector 21 passes through the shifter 25. It is introduced into the storage tank 26. The shifter 25 is provided with a net-shaped vibrating plate for pulverizing or removing a lump that has grown due to the solidification of the powders. A discharge port (not shown) is formed at a lower portion of the storage tank 26 so that the powder collected in the storage tank 26 can be appropriately discharged and conveyed to a packaging process or the like. If foreign matter is mixed in the powder or a lump that could not be crushed occurs, the shifter 25 removes the lump or the lump and discards it in a waste container 27.

The exhaust air from which the powder is separated in each cyclone dust collecting chamber 15 of the cyclone dust collecting apparatus 4 joins in the exhaust air line 5 and is then supplied to the next filter type dust collecting apparatus 6. I have. As shown in FIG. 2, the filter type dust collecting apparatus 6 of this embodiment has a cylindrical dust collecting chamber 30 in which an upper part is closed by a ceiling surface 31, and the inclined surface gradually becomes narrower toward the center of the bottom surface 32. It has a formed configuration. Dust chamber 30
A cylindrical filter bag 33 is mounted so as to partition the internal space of the filter vertically, and exhaust air is introduced into the filter type dust collecting device 6 from an exhaust line 5 connected to a lower portion of the dust collecting chamber 30. After the exhaust air passes through the filter bag 33 from below to above, the exhaust air is exhausted to the outside through an exhaust line 7 connected to the upper part of the dust collecting chamber 30. The filter bag 33 is provided with a metal frame 34 inside so as to maintain a cylindrical shape, and has a structure in which a replaceable filter cloth 35 is mounted around the frame 34. Further, in order to prevent a decrease in filtration performance due to powder adhering to the surface of the filter cloth 35, an air ejection nozzle 36 for blowing air from the inside of the filter cloth 35 to blow off the powder is provided. The operation of the air ejection nozzle 36 is periodically operated. This operation may be performed irrespective of the stoppage of the operation of the powder drying system 1, but is preferably performed during the operation of the powder drying system 1. It is preferable that the air be blown by shifting the air to prevent the powder from adhering to the filter cloth 35. In addition, it is preferable that the air ejection nozzle 36 is configured to be able to blow air to the entire filter cloth 35 by rotating. The compressed air supplied to the air jet nozzle 36 is produced by a compressed air production facility (not shown) and supplied from a pipe 37. In order to prevent powder contamination by the compressed air, the pipe 37 is used. A sterilization device, a high-precision sterilization filter, a compressed air cooling device, and the like are provided in the middle of the process.

When the exhaust air passes through the filter bag 33 as described above, the powder contained in the exhaust air is collected, and the powder is collected in the dust collection chamber 30 on the upstream side of the filter bag 33. It falls in the lower space. On the other hand, as shown in FIG.
8 and an exhaust tower 39 are connected, and by operating the exhaust fan 38, the exhaust air of the entire powder drying system 1 is reduced.
The air is exhausted to the outside. Exhaust tower 3
9 is provided with a sprinkler for separating fine powder mixed in the exhaust air.

As shown in FIG. 2, in the middle of the exhaust line 5 connected to the lower part of the dust collecting chamber 30, the dust collecting chamber 30 of the filter type dust collecting device 6 while the operation of the powder drying system 1 is stopped.
A heating mechanism 40 for preventing a temperature drop in the inside is mounted. In the illustrated example, the heating mechanism 40 has a configuration in which a heater 42 and an air intake filter 43 are attached to a heated air supply line 41. The clean air filtered by the air intake filter 43 is heated by the heater 42 and can be introduced into the dust collecting chamber 30 of the filter type dust collecting device 6 from the heated air supply line 41.

The bottom surface 32 of the dust collection chamber 30 formed on an inclined surface
A rotary valve 44 capable of maintaining airtightness in the dust collecting chamber 30 is mounted at the lowermost portion of the dust collecting chamber 30. By the operation of the rotary valve 44, the dust is collected by the filter bag 33 as described above. The powder that has fallen in the inside 30 is discharged downward. The rotary valve 44 hermetically closes the discharge port at the lower part of the dust collection chamber 30 with a plurality of blades 45.
Powder is accumulated between the five. Since the blades 45 are rotating, the powder is sequentially discharged downward.

As shown in FIG. 1, as shown in FIG.
A powder transfer line 46 for transferring the powder captured and collected in the dust collection chamber 30 to the secondary cyclone dust collector 21 described above is connected below the dust collection chamber 30. Also, the powder collected in the dust collecting chamber 30 of the filter type dust collecting device 6 is conveyed in the powder conveying line 46 by the suction operation of the exhaust fan 22 and the secondary cyclone dust collecting device. 21. Like the transfer line 20 described above, the powder transfer line 4
An air inlet 47 provided with a filter, an erofin tube for cooling, and the like is also formed upstream of the air inlet 6. In the example shown in the figure, a take-out line 49 is provided for taking out the powder collected by the filter-type dust collecting device 6 into the collection container 48 separately as needed without introducing the powder into the powder transfer line 46. ing.

As shown in FIG. 2, a heat insulating material 50 is mounted outside the bottom surface 32 formed on the inclined surface. This prevents the bottom 32 from being cooled by the outside air and from forming dew, and prevents the powder falling in the dust collection chamber 30 from adhering to the bottom 32. In the illustrated example, although wearing the heat insulating material 50 only on the bottom surface 32 of the dust collecting chamber 30, the top to, or instrumentation to entire outer surface of the dust collecting chamber 30 than
You may wear it.

As shown in FIG. 2, in the space upstream of the filter bag 33 inside the dust collection chamber 30 (in the example shown, in the space below the filter bag 33 inside the dust collection chamber 30), the filter bag In some cases, the powder captured by the filter 33 falls, and the powder adheres and accumulates on the inner wall surface of the dust collection chamber 30. In particular, in FIG.
At least two inner wall surfaces intersect each other as in the corner 55 where
There is a high possibility that the powder adheres and accumulates in a portion less than 0 °.
Therefore, the filter-type dust collecting device 6 of the present invention has a configuration in which a dusting-off mechanism 56 for preventing the powder from adhering and laminating to such corner portions 55 is provided.

In the illustrated example, the removing mechanism 56
The nozzle 57 is configured to blow the compressed gas toward the corner portion 55, and the compressed gas discharged from the nozzle 57 is blown toward the corner portion 55, thereby forming the corner portion 55.
This prevents the powder from adhering and laminating to the surface. Although the nozzle 57 may be fixed, it is preferable that the nozzle 57 be configured to be capable of rotating and oscillating so that the compressed gas can be blown over a wide range near the corner 55. When the compressed gas supplied to the nozzle 57 is air, the compressed gas is produced in a compressed air production facility (not shown) and supplied through a pipe 58. In order to prevent powder contamination by the air,
A sterilization device, a high-precision sterilization filter, a compressed air cooling device, and the like are provided in the middle of the pipe 58.

According to the powder drying system 1 configured as described above, the powder obtained in the drying chamber 12 of the drying device 2 is supplied from the exhaust line 3 to the cyclone dust collecting device 4, and the cyclone dust is collected. The powder dropped in the chamber 15 can be collected in the secondary cyclone dust collector 21 through the powder transport line 20 from the outlet 16 below the cyclone dust collecting chamber 15.
Further, the exhaust air separated from the powder in the cyclone dust collecting chamber 15 of the cyclone dust collecting device 4 is supplied to the filter type dust collecting device 6 through the exhaust line 5. The powder captured and collected by the filter bag 33 in the dust collection chamber 30 can also be collected in the secondary cyclone dust collector 21 via the powder transfer line 46. As described above, according to the powder drying system 1 of the illustrated embodiment, the powder contained in the exhaust air of the cyclone dust collector 4 that has been conventionally discarded is captured by the filter dust collector 6. By collecting, the powder obtained by the drying device 2 can be used without waste, and the efficiency is high. Further, since powder is not contained in the exhaust gas discharged to the outside, there is no environmental problem at all.

In the filter-type dust collecting device 6, the compressed air discharged from the nozzle 57 as the sweeping-off mechanism 56 causes the corners 55 in the dust collecting chamber 30 where powder is particularly likely to adhere and stack. Can be prevented from adhering and accumulating powder on the inner surface of the dust collecting chamber 30. Then, the powder captured by the filter bag 33 and dropped in the dust collecting chamber 30 falls downward along the bottom surface 32 formed on the inclined surface, and the rotary valve 44 mounted at the lowermost position.
Can be introduced into the powder conveying line 46 through
At that time, heat is kept outside the bottom surface 32 of the filter type dust collector 6.
Since the material 50 is mounted, the inner surface of the bottom surface 32 is not cooled by the external air, and dew condensation can be prevented. Therefore, the powder does not adhere to and stack on the bottom surface 32. The dust is discharged outside the dust collection chamber 30.

On the other hand, while the operation of the powder drying system 1 is stopped, the air which is clean and heated by the heating mechanism 40 provided in the exhaust air line 5 is supplied to the dust collecting chamber of the filter type dust collecting device 6. Since it is introduced into the dust collecting unit 30, the dew condensation in the filter type dust collecting device 6 can be prevented even during the operation stop of the powder drying system 1, and the powder can be prevented from adhering to the inner wall of the dust collecting chamber 30. By sending dry air into the dust collecting chamber 30 by the heating mechanism 40 when the powder drying system 1 is stopped, high-humidity drying device exhaust air is discharged from the dust collecting chamber 30. Will be able to

In operating the powder drying system 1 as described above, unless the air pressure in the drying chamber 12 of the drying device 2 is lower than the atmospheric pressure, the atmosphere in the drying chamber 12 may leak out. is there. Therefore, it is preferable that the exhaust capacity of the exhaust fan 38 be larger than the blow capacity of the blower 10.
Although not shown, the drying device 2 and the filter-type dust collecting device 6 are partially provided with a door constituting an entrance so that a person can enter the inside to perform a cleaning operation or a filter replacement operation. In addition, the operation platform is designed to be fixed or attachable and detachable. Further, the exhaust lines 3, 5, 7 and the like are provided with a damper for maintaining airtightness in order to prevent contamination of the system during operation stop. This damper may be used for adjusting the amount of air depending on the opening degree. This damper is also provided on the upper portion of the storage tank 26, the transfer lines 20, 46, and the like. In addition, although not shown, the secondary cyclone dust collector 21
A small filter bag is also provided in the air exhaust line to prevent scattering of powder.

[0039]

Next, an embodiment of the present invention will be described with reference to an example using a milk powder manufacturing facility. (A) Equipment Capacity, Milk Powder Production Conditions, and Operating Conditions of the Apparatus In the examples, data obtained by installing and operating the apparatus of the present invention in an actual milk powder production line are shown. Table 1 shows the capacities of the main production facilities, and Table 2 shows the milk powder production conditions when the data was collected. Table 3 also shows the performance and operating conditions of the various devices and systems shown for comparison. In addition, all data are performed in the same process and manufacturing conditions.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

As for the peripheral device of the filter type dust collector, a single fluid spray nozzle is used as the adhesion preventing nozzle. The nozzle diameter is 1mm. The air supply source uses the air for purging the filter bag and is operated periodically by sequence control. Although the wiping is performed by the pulse jet method, the wiping effect is enhanced by entraining 5 to 7 times the air injected from the surroundings by the Venturi effect. In the apparatus of the embodiment, four units were installed at positions 10 cm above the four corners of the interior of the dust collection chamber where the adhesion and lamination were the largest.

Heating device at rest, heater: rated 7k
W, fan: rated at 2.0 kW, powder discharger was a stainless steel rotary valve, and outer wall insulation was such that the powder hopper was insulated from the outside air with heat insulating material.

The method of measuring the quality of the recovered powder is as follows. 1. Microorganisms a) General bacterial count: Samples should be at an appropriate concentration (10 times or 1
(00 times), pour culture using standard agar medium (culture temperature: 32-35 ° C, culture time 45-48 hours), and estimate the number of viable bacteria in the sample from the number of colonies that have grown and formed. I do. b) Number of thermophilic bacteria: The sample was prepared at an appropriate concentration (10 times or 10
(0 times), pour culture using a standard agar medium (culture temperature: 55 ° C., culture time: 45 to 48 hours), and estimate the number of viable bacteria in the sample from the number of colonies that have grown and formed. c) Mold: The sample was diluted to an appropriate concentration and pH 3.5 ±
After pour culture using a potato dextrose agar medium adjusted to 0.1, the number of molds in the sample is estimated from the number of colonies formed by growth.

2. Solubility a) Sensory evaluation: 10 g of a sample is collected in a 200 ml beaker, and 90 ml of hot water at 60 ° C. is dissolved while stirring with a spatula. At this time, stirring is performed 20 times at a speed of 3 times / second, and the state of the stirring, curd, and undissolved matter is checked immediately after stirring. b) Insolubility (ADMI): “IDF STANDARD 129A: 19
88 Method for measuring the insolubility of milk powder and milk powder products ". ADM containing water at 24 ° C in advance
10 g of a sample is added to a container specified by I and stirred and dissolved by a mixer specified by ADMI for 90 seconds. After dissolution, stir with a spoon for 5 seconds and immediately pour up to 50 ml into two centrifuge tubes. Then, centrifuge for 5 minutes. After completion of the centrifugation, the supernatant liquid is removed to 2 ml above the surface of the precipitate with an aspirator, and water at 24 ° C. is injected to the mark of 50 ml, and the mixture is thoroughly mixed and stirred with the precipitate. After centrifugation again for 5 minutes, the volume of the precipitate is read.

3. Sediment The surface is smoothed with a spoon or the like in the powder state, and the presence of burnt powder, agglomeration, and foreign matter is checked. A dissolved sample (30 g of a sample was collected in a 200 ml beaker, and
(Dissolved completely in 200 ml of hot water at 200 ° C.) with a sediment disk (diameter 33 mm, Toyo Filter Paper No. 102).
Perform filtration according to 6), and also check sediment on the disk.

The collection efficiency of the dust collector / system was determined by the following equation based on the dust concentration in the exhaust air before and after the treatment.

Collection efficiency (%) = (AB) / A × 100 A: Inlet air dust concentration (g / Nm ³ ) B: Outlet air dust concentration (g / Nm ³ )

The dust concentration was measured in accordance with JIS Z 8808, "Method for Measuring Dust Concentration in Flue Gas". In this measurement method, a collection device (dust tube) for collecting dust is inserted into the exhaust duct, a part of the exhaust air is sucked, and the amount of dust collected in the dust tube and the sucked air This is a method of calculating the amount of dust per unit volume from the amount.

Table 4 shows the quality of the powder recovered by the apparatus of the present invention. In addition, the quality of the powder collected by the system using the cyclone and the conventional commercially available filter-type dust collector (using the filter-type dust collector before customizing the device mechanism of the present invention) is also shown.

[0052]

[Table 4]

With respect to the powder recovered by the ordinary filter-type dust collector, the microbial quality is determined by the general bacteria count of 100 to 10,000.
In addition to the high level of 0 cells / g and the high-temperature bacteria count of 100 to 1,000 cells / g, it is contaminated with mold and is not of edible quality. In addition, since there are many browning and solidified powders generated by the adhesion and lamination on the inner wall of the apparatus, the solubility is not only high in insolubility (2.0 to 4.0 ml), but also in terms of organoleptic properties. Melts poorly below the point. Furthermore, the sediment is not good at 3 points or less due to the very large amount of the burnt powder. On the other hand, the quality of the powder recovered by the apparatus of the present invention is slightly inferior in solubility and sediment to ordinary products, but the microbial quality is equivalent to that of ordinary products, and is sufficiently usable. Can meet criteria.

Table 5 shows the collecting performance of the apparatus of the present invention. For comparison, the performance of a cyclone dust collector alone, a system combining a cyclone and a louver dust collector, and a system combining a cyclone and a water shower type wet dust collector are also shown.

[0055]

[Table 5]

As is clear from the table, the collection efficiency was 99.9%.
Can be cleared only by the device of the present invention. Among the other dust collectors / systems, the collection efficiency of the system combining the cyclone and the louver dust collector is 99.4%, which is the best, but much lower than the performance of this system.

[0057]

According to the present invention, the powder recovery rate of the whole system can be made almost 100%, the product yield can be improved, and the powder can be prevented from escaping to solve the pollution problem. It is possible. If powder accumulates or accumulates on the wall in the dust collecting chamber of the filter type dust collector, it will cause the generation of microorganisms due to the effect of humidity and temperature, causing not only the powder itself but also the device itself. As a result, efficient powder collection cannot be performed, but according to the present invention,
In addition to the structure to prevent powder from adhering to the wall surface and preventing stagnation, measures to prevent sudden temperature changes in the dust collection chamber are added.
The quality of the recovered powder can be maintained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a powder drying system according to an embodiment of the present invention.

FIG. 2 is a sectional view of a filter-type dust collecting device provided in the powder drying system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Powder drying system 2 Drying device 3,5,7 Exhaust air line 4 Cyclone dust collecting device 6 Filter type dust collecting device 30 Dust collecting room 32 Bottom surface 33 Filter bag 40 Heating mechanism 44 Rotary valve 50 Heat insulating material 56 Discharge mechanism 57 nozzles

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-55332 (JP, A) JP-A-59-22623 (JP, A) JP-A-6-329255 (JP, A) 25717 (JP, U) Fully open sho 56-154817 (JP, U) Fully open sho 61-135585 (JP, U) Fully open sho 54-106562 (JP, U) Fully open flat 4-34649 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B01D 46/04 B04C 5 /

Claims (3)

(57) [Claims] 1. A filter-type dust collecting apparatus for collecting powder contained in air by passing air containing powder through a filter bag disposed so as to partition an internal space of the dust collecting chamber. Slope that gradually narrows toward the bottom
And discharge the powder to the bottom of the bottom.
And the bottom of the dust collection chamber intersect
A filter type dust collecting device comprising a nozzle for blowing compressed gas toward a corner . 2. The nozzle is fixed or rotating.
And / or is configured to be able to swing.
The filter type dust collector according to claim 1, wherein 3. Introducing heated clean air into the dust collection chamber.
And a heat insulating material on the outside of the bottom.
The filler according to claim 1, wherein the filler is worn.
Type dust collector.