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Q What are the key points to consider when buying a vacuum screw dryer?
A When buying a vacuum screw dryer, the key factors to consider are vacuuming and drying time, condenser efficiency, pumping volume, etc. In addition, the composition of the moisture to be extracted is also a very important factor because it affects the operating pressure.
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Q How to solve the problem of horizontal seal sticking to the knife of the vertical packaging machine
A First of all, we need to understand the sealing mode of the packaging machine: first, the horizontal seal is heated by the heating tube to seal the plastic film. The horizontal seal has a built-in cutter, and the cutter extends to cut the bag when sealing. The horizontal seal sticking to the cutter has a lot to do with temperature and film.
1. The temperature is too high, causing the film to melt and adhere to the horizontal seal. When the cutter extends, the melted film will adhere to the cutter. At this time, we can wipe the horizontal seal position clean with a brush, and at the same time, adjust the temperature of the horizontal seal, and then try to pack.
2. In addition to controlling the temperature, the sealing time also needs to be considered. Too long will also cause the above problems.
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Q What are the disadvantages of using a belt dryer?
A 1. Large space requirement: They occupy significant floor space.
2. Potential for uneven drying: If not properly loaded, the material might not dry uniformly.
3. Maintenance: Requires regular cleaning to avoid cross-contamination, especially in food and pharmaceutical applications.
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Q Differences between belt dryer and hot air circulation oven
A 1. Belt dryer has transmission device, while hot air circulation oven does not, which is determined by the design principle of the equipment.
2. Hot air circulation oven loading requires manual placement of materials on the baking tray, and then placing the baking tray on the drying cart and pushing it into the oven, while belt dryer can achieve automatic drying, and the material can be dropped onto the mesh belt through the feeder.
3. Hot air circulation oven is an intermittent production equipment, while belt dryer is a continuous drying equipment.
4. Hot air circulation oven is suitable for small batch production, while belt dryer is suitable for large batch continuous production.
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Q Causes and solutions for not falling off balls
A 1. The powder material moisture is too high : Use dry material
2. Insufficient pressure strength of ball : Reduce gap between two rollers
3. Rough surface of mould ball : Grind with abrasive material
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Q Causes and solutions for not forming balls or pancakes
A 1. Insufficient feeding : The feeding qty should be sufficient
2. Too large gap : Adjust gap between rollers
3. Small gap at both ends and large in the middle : Grind off both sides to reduce gap
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Q Causes and solutions for circumferential misalignment of granule ball
A 1. Adjustment sleeve bolt loosen : Tighten bolts after aligning
2. Roller cover and shaft loosen : Replace roller cover or shaft
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Q Requirements for Mixing Equipment
A Considering the characteristics of the powder, the equipment should possess: good mixing uniformity, no dead corners, high mixing efficiency, low power consumption, etc. The mixing equipment should not alter the physical properties of the powder, such as density, average particle size, and particle surface shape. Furthermore, the mixing equipment should operate safely, be easy to operate, save energy, and reduce labor costs.
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Q Selection Principles for Mixing Equipment
A 1. Choose ordinary models like V-shaped mixers for easy mixing tasks; for challenging tasks, opt for high-performance mixers.
2. Use forced shear mixing machines for powders with poor flowability.
3. For powders that are difficult to mix, such as ultra-light or ultrafine powders, choose composite mixers that combine gravity diffusion with forced agitation.
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Q What is the implementation methods of powder mixing
A 1.Gravity Convection Diffusion Mixing Method This method continuously raises the center of gravity of the powder, utilizing gravity to force the powder to undergo repeated flow, diffusion, collision, folding, and other movements. Its purpose is to macroscopically intermix and infiltrate powder particles, thereby achieving uniform mixing.
2.Forced Shear Mixing Method
Utilizing the motion of the stirring blades within the container to forcefully stir and shear the powder repeatedly. Its purpose is to microscopically break up the adjacent relationships between powder particles, allowing them to move and exchange fully, achieving uniform powder mixing.
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Q What is the principles of powder mixing
A 1.Diffusion Mixing: Small-scale layer-by-layer diffusion movement of powder particles. Under external forces, separated powder particles move to continuously emerging new layers, allowing the components of the powder to diffuse and achieve uniform distribution within a local range. The conditions for diffusion mixing are: powder particles distributed on continuously emerging new layers.
2.Convection Mixing: Large-scale random movement of powder particles. Under external forces, powder particles undergo fluid-like motion, moving from one point to another within the material, enabling powder particles to convect and achieve uniform distribution over a large range.
3.Shear Mixing: Internal shearing of powder material masses. Under external forces, powder particles experience mutual slipping, forming shear planes, continuously shearing local powder to achieve uniform distribution.
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Q Common problems and solutions during dry granulation process
A Common problems in the dry granulation process include:
High proportion of granules and fine powder, uniformity of compression, and material sticking to the roller.
1.The proportion of fine powder is relatively high: one solution is to use a grooved roller, and the uncompacted material usually leaks out from the side of the roller; the second method is to re-compress the fine powder. There is a risk, but repeated compaction of the material may cause it to lose its compressibility and affect the quality of the tablets; the third solution is to install vacuum degassing equipment.
2.Uniformity of compression: The pressure on the surface of the roller is not uniform. Even the pressure on materials in the same area will change with time. The fluctuation of pressure is mainly affected by the compression structure of the roller and the uniformity of the feed of the mixed material. Influence. The solution to the roller compression structure is to use a roller with narrow wheels on the edge to reduce the movement of the compressed material and make the material evenly distributed; the solution to the uniformity of the mixed material feed is to adjust the screw feeder speed and adjust the fluidity of the mixed material.
3.Material sticking to the roller: The problem of material sticking to the roller is relatively simple and can be solved by controlling the moisture content of the mixed material, adding lubricant, and repeated extrusion.
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Q Factors affecting dry granulation process
A Generally, there are three main variables in the dry granulation rolling process: pressure, feed screw speed and roller speed; there are two main auxiliary materials in the mixed powder that have a greater impact on rolling: binders and lubricants, and easy Affected by the moisture content of the material.
1.The moisture content of the material affects: the deformation and tensile strength of the material, thereby affecting the compressibility of the tablet; therefore, during the dry granulation process, the moisture content must be strictly controlled even for the same material.
2.Influence of lubricants: The addition of lubricants will affect the compressibility of some materials. The amount and method of adding lubricants are the two most important aspects that affect the compressibility of tablets. In addition, the crystal form of the same lubricant and The specific surface area also affects the compressibility of the mixture.
3.Influence of binder: Binder can compensate for the loss of particle hardness, reduce the amount of fine powder during dry granulation and ensure the tensile strength of tablets; the correct selection of binder is important for the dry granulation process, especially For brittle API materials, particle size distribution is a key material attribute of adhesives.
4.Influence of roller pressure: When the roller pressure is low, the difference in compressibility loss for the same material is very small, but when the roller pressure is high, the compressibility loss of the same material will be large. Particles prepared at lower pressures have more pores and are more likely to break during tableting, resulting in high compressibility.
5.Influence of physical properties: Many APIs and excipients have different physical forms, including polymorphs, solvates, and amorphous forms. Even for the same material, there are batch-to-batch differences, such as particle size distribution, morphology (crystal form, crystal habit, agglomeration), surface roughness, etc., which will also affect the compressibility of the material during the dry granulation process.
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Q How to choose the material of hot air circulation ovens?
A 1.Mainly including stainless steel, carbon steel, aluminum alloy, etc. Stainless steel has the characteristics of corrosion resistance, high temperature resistance, and easy cleaning, and is widely used in the fields of medicine and chemical industry; carbon steel is cheap but prone to rust, and is generally used in occasions where drying is carried out at low temperatures; aluminum alloy has the advantages of light weight and good thermal conductivity, but has a higher cost and is generally used in the field of high-precision drying.
2.The thickness of the material is also one of the key factors to consider. For materials dried at room temperature, a thickness of about 2-3mm of carbon steel is generally sufficient; for materials dried at high temperatures, the thickness of stainless steel generally needs to be above 3-5mm to ensure its high temperature resistance.
In addition, it is also necessary to consider whether insulation materials need to be installed inside the hot air circulation oven. Installing insulation materials can improve the heating efficiency of the oven, reduce energy waste, and also reduce heat loss to ensure the temperature stability of the oven.
3.The selection of materials for hot air circulation ovens also needs to consider the nature of the materials and process requirements. For materials that are prone to explosion or combustion, stainless steel ovens can be equipped with explosion-proof devices to ens
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Q What are the door-opening methods of hot air circulation ovens?
A Front-opening door, front and rear-opening door, top-opening door, lift-up door.
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Q What are the hot air circulation ways?
A Choose the appropriate hot air circulation way according to the different arrangement of the baked products, such as bottom air circulation, top and bottom air circulation, front and rear air circulation, etc.
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Q What are the heating methods of hot air circulation ovens?
A Electric heating, fuel oil heating, gas heating, steam heating, mixed heating.
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Q Disadvantages of Vibrating Fluid Bed Dryers
A Vibrating fluidized bed dryers are limited to loose powders or granular materials. They cannot directly process materials in other states, such as pastes or liquids. This limitation restricts their application range and calls for improvement and expansion.
Uneven fluidization is a common issue with vibrating fluidized bed dryers. These issues can lead to inefficient inter-phase contact, thereby affecting drying effectiveness. Additionally, uneven fluidization results in uneven distribution of material residence time within the bed layer, leading to non-uniform moisture content in the products and even causing some products to deteriorate due to over-drying.
Vibrating fluidized bed dryers consume considerable power and thermal energy. Continuous vibration requires significant electrical energy to sustain operation. Moreover, achieving drying effectiveness requires heating the drying medium to high temperatures, resulting in substantial energy consumption.
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Q How to choose the right vacuum screw dryer?
A Choosing the appropriate vacuum screw dryer involves considering factors such as material properties, drying requirements, and production capacity. It is recommended to collaborate with professional drying equipment manufacturers for customized selection to ensure optimal drying performance and production efficiency.
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Q What is the price range of the vacuum screw dryer?
A The price of a vacuum spiral dryer is generally higher than that of other types of drying equipment due to its complex structure and high drying performance. However, considering its efficiency and quality drying results, investing in a vacuum spiral dryer typically provides excellent value for money.