Fluidized bed spray agglomeration granulator for instant milk powder granules

Abstract

The application provides a fluidized bed spray agglomeration granulator for instant milk powder granules, comprising: a spray granulation tower, a first connecting pipe connected to the discharge end of the spray granulation tower; a cyclone separator, the output end of the first connecting pipe being in communication with the air inlet end of the cyclone separator, used for performing primary gas-solid separation on the mixed gas stream output by the spray granulation tower; and a pulse filter, the air outlet end of the cyclone separator being in communication with the air inlet end of the pulse filter, used for trapping and filtering the powder escaping from the air outlet end of the cyclone separator. By additionally arranging the pulse filter at the air outlet end of the cyclone separator, the application can trap the fine dust particles that cannot be captured by the cyclone separator and recycle them, thereby reducing the loss of raw materials, improving the total product yield, and greatly reducing the dust content of the tail gas finally discharged into the atmosphere, thereby reducing the pollution pressure on the environment and meeting more stringent environmental emission standards.

Description

Technical Field

[0001] This invention relates to the field of milk powder instant granule processing technology, and more specifically, to a fluidized bed spray agglomeration granulation device for milk powder instant granules. Background Technology

[0002] In the production of milk powder and instant beverages, fluidized bed spray agglomeration granulation technology is a key means to improve the solubility, flowability, and appearance of products. Traditional spray agglomeration granulation devices typically include a spray granulation tower, a cyclone separator, and an exhaust system. The basic workflow is as follows: the liquid material is atomized and then dried in the tower by contact with hot air to form milk powder granules; simultaneously, the system maintains a negative pressure state through an exhaust fan to discharge dust-laden exhaust gas. During operation, the cyclone separator, as a primary gas-solid separation device, is responsible for recovering the finer powder entrained in the exhaust gas. However, the separation efficiency of the cyclone separator has a theoretical limit, especially for ultrafine or light powders. Fine powders that cannot be captured escape from the cyclone separator outlet with the high-speed airflow, causing not only a loss in yield and waste of resources but also increasing the load on subsequent exhaust gas treatment. Therefore, we have made improvements and proposed a fluidized bed spray agglomeration granulation device for instant milk powder granules. Summary of the Invention

[0003] This invention provides a fluidized bed spray agglomeration granulation device for instant milk powder granules, comprising: A spray granulation tower, wherein the discharge end of the spray granulation tower is connected to a first connecting pipe; Cyclone separator, the output end of the first connecting pipe is connected to the air inlet end of the cyclone separator, used to perform primary gas-solid separation on the mixed airflow output from the spray granulation tower; A pulse filter is provided, wherein the air outlet of the cyclone separator is connected to the air inlet of the pulse filter, and is used to intercept and filter the powder escaping from the air outlet of the cyclone separator, so as to reduce the loss of milk powder raw materials with the exhaust gas. The exhaust fan is connected to the outlet of the pulse filter via a third connecting pipe. The exhaust fan is used to establish a negative pressure for suction from the spray granulation tower to the pulse filter.

[0004] As a preferred technical solution of this application, the solid output end of the cyclone separator is connected to a first particle output pipe, the bottom end of the pulse filter is connected to a discharge valve, the discharge valve is connected to a second particle output pipe, the second particle output pipe and the first particle output pipe are merged downstream to form a main discharge pipe, and the main discharge pipe is connected to the finished powder silo; and an online moisture detector is installed in the main discharge pipe.

[0005] As a preferred technical solution of this application, a hot air pipe is provided on the spray granulation tower, and a hot air fan is connected to the end of the hot air pipe away from the spray granulation tower. The hot air fan is used to cooperate with the hot air pipe to deliver hot air into the spray granulation tower.

[0006] As a preferred technical solution of this application, the spray granulation tower is provided with a conveying pipe, and a conveying pump is connected to the end of the conveying pipe away from the spray granulation tower. The conveying pump and the conveying pipe cooperate to convey the milk to the spray granulation tower for atomization and spraying.

[0007] As a preferred technical solution of this application, the following granulation step is also included: S1: Start the hot air blower to create a gradient temperature field from top to bottom in the spray granulation tower. The inlet air temperature is 150℃-170℃. At the same time, control the pressure of the delivery pump to atomize the milk through the delivery pipe into particles with a diameter of 20μm-50μm. The atomization angle is controlled at 55°-70°. S2: During the falling process, the atomized droplets undergo transient dehydration with the hot air in the spray granulation tower. After forming a semi-dry gel layer on the surface, they undergo initial collision and aggregation at the bottom cone section of the spray granulation tower, forming primary agglomerated particles. S3: Two-stage negative pressure gradient capture: Primary agglomerated particles enter the cyclone separator with the airflow through the first connecting pipe to complete the first stage of gas-solid separation; the fine powder that escapes from the cyclone enters the pulse filter with the airflow, and the exhaust fan is controlled to maintain the negative pressure at -300Pa to -500Pa, and the back-flushing cycle of the pulse filter is set to a spray interval of 15s-25s and a pulse width of 0.08s-0.12s; S4: After the coarse particles output from the cyclone separator and the fine powder output from the pulse filter are combined in the main discharge pipe, the data from the online moisture detector is fed back simultaneously. When the initial moisture content of the combined powder is >10%, the fluidized bed cooling and drying time is automatically extended to 18min-22min, so that the final moisture content of the finished particles is ≤3%.

[0008] As a preferred technical solution of this application, a static mixer is provided at the confluence node of the main discharge pipe. The static mixer is located upstream of the online moisture detector and is used to eliminate the temperature gradient and moisture segregation between the first particle output pipe and the second particle output pipe.

[0009] As a preferred technical solution of this application, in S4, a stepped cooling mode is adopted: the front section uses 55℃-60℃ hot air to sweep away the bound water on the particle surface, the middle section switches to 45℃ clean air to balance the internal moisture migration of the particles, and the final section introduces 2℃-8℃ refrigerated dehumidifying air for rapid cooling and shape locking, with a rapid cooling time of not less than 3 minutes.

[0010] As a preferred technical solution of this application, in the final stage of the stepped cooling mode, the vibration exciter of the fluidized bed is turned on while the refrigeration dehumidification air is introduced. The vibration frequency is 20Hz-30Hz and the amplitude is 1mm-2mm, which is used to prevent the particles from sticking and agglomerating during the rapid cooling process.

[0011] As a preferred technical solution of this application, before the milk enters the delivery pump, it undergoes two-stage homogenization in a homogenizer. The first-stage homogenization pressure is 15MPa-20MPa, the second-stage homogenization pressure is 3MPa-5MPa, and the homogenization temperature is 50℃-60℃, so as to refine the fat globule particle size in the milk to ≤1μm, thereby improving the uniformity of atomization and the solubility of the final product.

[0012] As a preferred technical solution of this application, it also includes: taking samples of finished product particles from the finished product powder silo and conducting in vitro dissolution tests at a frequency of once every 2 hours or no less than 3 times per batch. The test conditions are: deionized water temperature 50℃±1℃, stirring speed 200rpm, recording the complete dispersion time of the particles, and when the complete dispersion time is >15s, adjusting the atomization pressure and cooling rate to maintain batch consistency of the quick-dissolving performance of the finished product.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: By adding a pulse filter at the outlet of the cyclone separator, this application can intercept and recover finer dust particles that the cyclone separator cannot capture, reducing raw material loss and increasing the overall product yield. The pulse filter significantly reduces the dust content of the exhaust gas discharged into the atmosphere, alleviating the pollution pressure on the environment and meeting stricter environmental emission standards. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the fluidized bed spray agglomeration granulation device for instant milk powder granules provided in this application. Figure 2 A top view of the fluidized bed spray agglomeration granulation device for instant milk powder granules provided in this application; Figure 3 A partial bottom view of the fluidized bed spray agglomeration granulation device for instant milk powder granules provided in this application; Figure 4 This is a block diagram of the fluidized bed spray agglomeration granulation device for instant milk powder granules provided in this application.

[0015] The image shows: 2. Spray granulation tower; 3. Hot air duct; 4. Hot air blower; 5. Conveying pipe; 6. Conveying pump; 7. First connecting pipe; 8. Cyclone separator; 9. First particle output pipe; 10. Second connecting pipe; 11. Third connecting pipe; 12. Exhaust fan; 13. Second particle output pipe; 14. Pulse filter. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0017] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0018] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0019] Example 1, please refer to Figure 1-4 A fluidized bed spray agglomeration granulation device for instant milk powder granules, comprising: The spray granulation tower 2 has a first connecting pipe 7 connected to its discharge end; The output end of the first connecting pipe 7 of the cyclone separator 8 is connected to the air inlet end of the cyclone separator 8, and is used to perform primary gas-solid separation on the mixed airflow output from the spray granulation tower 2. The pulse filter 14 is connected to the air inlet of the cyclone separator 8. It is used to intercept and filter the powder that escapes from the air outlet of the cyclone separator 8, so as to reduce the loss of milk powder raw materials with the exhaust gas. A third connecting pipe 11 is connected between the exhaust fan 12 and the air outlet of the pulse filter 14. The exhaust fan 12 is used to establish a suction negative pressure from the spray granulation tower 2 to the pulse filter 14.

[0020] Furthermore, the solid output end of the cyclone separator 8 is connected to the first particle output pipe 9, and the bottom end of the pulse filter 14 is connected to the discharge valve, which is connected to the second particle output pipe 13. The second particle output pipe 13 and the first particle output pipe 9 are merged downstream to form a main discharge pipe, which is connected to the finished product powder silo. An online moisture detector is installed in the main discharge pipe. The online moisture detector can provide real-time feedback of moisture content data, providing a basis for the dynamic adjustment of subsequent drying parameters and reducing product quality problems caused by moisture fluctuations.

[0021] Furthermore, a hot air pipe 3 is provided on the spray granulation tower 2. A hot air fan 4 is connected to the end of the hot air pipe 3 away from the spray granulation tower 2. The hot air fan 4 is used to cooperate with the hot air pipe 3 to deliver hot air into the spray granulation tower 2. The hot air comes into direct contact with the atomized droplets, and the water on the surface of the droplets evaporates rapidly through forced convection heat and mass transfer to granulate the droplets.

[0022] Furthermore, a conveying pipe 5 is provided on the spray granulation tower 2. The end of the conveying pipe 5 away from the spray granulation tower 2 is connected to a conveying pump 6. The conveying pump 6 and the conveying pipe 5 work together to convey the milk to the spray granulation tower 2 for atomization and spraying.

[0023] Example 2 further optimizes the fluidized bed spray agglomeration granulation device for instant milk powder granules provided in Example 1. Specifically, it also includes the following granulation steps: S1: Start the hot air blower 4 to create a gradient temperature field from top to bottom inside the spray granulation tower 2, with an inlet air temperature of 150℃-170℃. The high inlet air temperature causes the surface of the droplets to form a crust quickly, while the temperature decreases downward inside the spray granulation tower 2, reducing the risk of breakage caused by violent vaporization of moisture inside the particles. At the same time, control the pressure of the delivery pump 6 to atomize the milk through the delivery pipe 5 into particles with a diameter of 20μm-50μm. The atomization angle is controlled at 55°-70°. The atomization angle of 55°-70° ensures that the droplets are evenly distributed on the cross-section of the spray granulation tower 2, reducing wall adhesion and improving the yield. S2: During the falling process, the atomized droplets undergo transient dehydration with the hot air in the spray granulation tower 2. After a semi-dry gel layer is formed on the surface, the droplets undergo initial collision and aggregation at the bottom cone section of the spray granulation tower 2, forming primary aggregated particles. By utilizing the transient dehydration during the droplet falling process and the collision and aggregation at the bottom cone section, primary aggregated particles with a loose and porous structure can be naturally formed. S3: Two-stage negative pressure gradient capture: Primary agglomerated particles enter the cyclone separator 8 through the first connecting pipe 7 with the airflow to complete the first stage of gas-solid separation; the fine powder that escapes from the cyclone enters the pulse filter 14 with the airflow, and the exhaust fan 12 is controlled to maintain the negative pressure at -300Pa to -500Pa, and the backflush cycle of the pulse filter 14 is set to a spray interval of 15s-25s and a pulse width of 0.08s-0.12s; through two-stage negative pressure gradient capture and optimized pulse backflush parameters, effective classification and recovery of coarse and fine particles are achieved, and the long-term stable operation of the pulse filter 14 is guaranteed. S4: After the coarse particles output from the cyclone separator 8 and the fine powder output from the pulse filter 14 are combined in the main discharge pipe, the data from the online moisture detector is simultaneously fed back. When the initial moisture content of the combined powder is >10%, the fluidized bed cooling and drying time is automatically extended to 18min-22min, so that the final moisture content of the finished particles is ≤3%. When the initial moisture content is too high, extending the fluidized bed drying time can provide additional mass transfer driving force, which promotes the diffusion and evaporation of bound water inside the particles until the critical moisture content of ≤3% is reached, thereby inhibiting microbial growth and preventing agglomeration.

[0024] Furthermore, a static mixer is installed at the junction of the main discharge pipes. The static mixer is located upstream of the online moisture detector and is used to eliminate the temperature gradient and moisture segregation between the first particle output pipe 9 and the second particle output pipe 13.

[0025] Furthermore, in S4, a stepped cooling mode is adopted: the first stage uses 55℃-60℃ hot air to sweep away the bound water on the particle surface, the middle stage switches to 45℃ clean air to balance the internal moisture migration of the particles, and the last stage introduces 2℃-8℃ refrigerated dehumidifying air for rapid cooling and shape locking, with a rapid cooling time of no less than 3 minutes.

[0026] Furthermore, in the final stage of the stepped cooling mode, while introducing refrigerant dehumidifying air, the vibration exciter of the fluidized bed is turned on, with a vibration frequency of 20Hz-30Hz and an amplitude of 1mm-2mm, to prevent the particles from sticking together and agglomerating during the rapid cooling process. During the rapid cooling stage, a local supersaturated water film may appear on the particle surface due to the sudden drop in temperature. When the particles come into contact with each other, liquid bridges are easily formed. After cooling, the liquid bridges solidify, leading to agglomeration.

[0027] Furthermore, before entering the delivery pump 6, the milk undergoes two-stage homogenization in a homogenizer. The first-stage homogenization pressure is 15MPa-20MPa, and the second-stage homogenization pressure is 3MPa-5MPa. The homogenization temperature is 50℃-60℃, which refines the fat globule particle size in the milk to ≤1μm, thereby improving atomization uniformity and the solubility of the final product, and enhancing the atomization effect and the wetting and dispersibility of the final product.

[0028] Furthermore, it also includes: taking samples of finished product granules from the finished product powder silo and conducting in vitro dissolution tests at a frequency of once every 2 hours or no less than 3 times per batch. The test conditions are: deionized water temperature 50℃±1℃, stirring speed 200rpm, recording the time for complete dispersion of granules. When the complete dispersion time is >15s, the atomization pressure and cooling rate are adjusted to maintain batch consistency of the product's instant dissolution performance.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Obviously, the embodiments described above are merely some embodiments of the present invention, not all embodiments. The accompanying drawings show preferred embodiments of the present invention, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this invention.

Claims

1. A fluidized bed spray agglomeration granulation device for instant milk powder granules, characterized in that, include: The spray granulation tower (2) is connected to a first connecting pipe (7) at its discharge end. Cyclone separator (8), the output end of the first connecting pipe (7) is connected to the air inlet end of the cyclone separator (8), and is used to perform primary gas-solid separation on the mixed airflow output by the spray granulation tower (2); The pulse filter (14) is connected to the air inlet of the cyclone separator (8) and is used to intercept and filter the powder that escapes from the air outlet of the cyclone separator (8) in order to reduce the loss of milk powder raw materials with the exhaust gas. A third connecting pipe (11) is connected between the exhaust fan (12) and the outlet of the pulse filter (14). The exhaust fan (12) is used to establish a suction negative pressure from the spray granulation tower (2) to the pulse filter (14).

2. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 1, characterized in that, The solid output end of the cyclone separator (8) is connected to the first particle output pipe (9), the bottom end of the pulse filter (14) is connected to the discharge valve, the discharge valve is connected to the second particle output pipe (13), the second particle output pipe (13) and the first particle output pipe (9) are merged downstream to form a total discharge pipe, the total discharge pipe is connected to the finished powder silo; and an online moisture detector is installed in the total discharge pipe.

3. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 2, characterized in that, The spray granulation tower (2) is equipped with a hot air pipe (3), and a hot air blower (4) is connected to one end of the hot air pipe (3) away from the spray granulation tower (2). The hot air blower (4) is used to cooperate with the hot air pipe (3) to deliver hot air into the spray granulation tower (2).

4. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 3, characterized in that, The spray granulation tower (2) is equipped with a conveying pipe (5), and a conveying pump (6) is connected to one end of the conveying pipe (5) away from the spray granulation tower (2). The conveying pump (6) and the conveying pipe (5) cooperate to convey the milk to the spray granulation tower (2) for atomization and spraying.

5. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 4, characterized in that, It also includes the following granulation steps: S1: Start the hot air blower (4) to form a gradient temperature field from top to bottom in the spray granulation tower (2), with the air inlet temperature being 150℃-170℃; at the same time, control the pressure of the delivery pump (6) to atomize the milk through the delivery pipe (5) with a particle size of 20μm-50μm, and control the atomization angle at 55°-70°. S2: During the falling process, the atomized droplets undergo transient dehydration with the hot air in the spray granulation tower (2). After a semi-dry gel layer is formed on the surface, the droplets undergo initial collision and aggregation at the bottom cone section of the spray granulation tower (2), forming primary agglomerated particles. S3: Two-stage negative pressure gradient capture: Primary agglomerated particles enter the cyclone separator (8) through the first connecting pipe (7) with the airflow to complete the first stage of gas-solid separation; the fine powder that escapes from the cyclone enters the pulse filter (14) with the airflow, and the exhaust fan (12) is controlled to maintain the negative pressure at -300Pa to -500Pa, and the back-blowing cycle of the pulse filter (14) is set to a spray interval of 15s-25s and a pulse width of 0.08s-0.12s; S4: After the coarse particles output by the cyclone separator (8) and the fine powder output by the pulse filter (14) are combined in the main discharge pipe, the data of the online moisture detector is fed back synchronously. When the initial moisture content of the combined powder is >10%, the fluidized bed cooling and drying time is automatically extended to 18min-22min, so that the final moisture content of the finished particles is ≤3%.

6. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 5, characterized in that, A static mixer is installed at the junction of the main discharge pipe. The static mixer is located upstream of the online moisture detector and is used to eliminate the temperature gradient and moisture segregation between the first particle output pipe (9) and the second particle output pipe (13).

7. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 6, characterized in that, In S4, a stepped cooling mode is adopted: the first stage uses 55℃-60℃ hot air to sweep away the bound water on the particle surface, the middle stage switches to 45℃ clean air to balance the internal moisture migration of the particles, and the last stage introduces 2℃-8℃ refrigerated dehumidifying air for rapid cooling and shape locking, with a rapid cooling time of no less than 3 minutes.

8. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 7, characterized in that, In the final stage of the stepped cooling mode, while introducing refrigerant dehumidifying air, the vibration exciter of the fluidized bed is turned on, with a vibration frequency of 20Hz-30Hz and an amplitude of 1mm-2mm.

9. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 5, characterized in that, Before entering the delivery pump (6), the milk is homogenized in two stages by a homogenizer. The first homogenization pressure is 15MPa-20MPa, the second homogenization pressure is 3MPa-5MPa, and the homogenization temperature is 50℃-60℃.

10. The fluidized bed spray agglomeration granulation device for instant milk powder granules according to claim 5, characterized in that, It also includes: taking samples of finished product granules from the finished product powder silo and conducting in vitro dissolution tests at a frequency of once every 2 hours or no less than 3 times per batch. The test conditions are: deionized water temperature 50℃±1℃, stirring speed 200rpm, recording the time for complete dispersion of the granules, and adjusting the atomization pressure and cooling rate when the complete dispersion time is >15s.

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