The upper exhaust spray fluidized granulation dryer is one of the most successful designs of spray drying equipment.It can be used in many kinds of products, especially those materials which are difficult to powder forming with traditional drying technology.

The technology of upper exhaust spray fluidized granulation dryer combines fluidized bed drying technology and spray granulation technology, making the particle shape and size easy to control.In addition, it is often used as spray drying adhesion or spray drying granulation.The drying process can be completed while maintaining a low powder temperature. Another important function is that it can be well applied to the drying and forming of heat-sensitive products.

Control particle size and shape and powder characteristics

Because spray granulation and fluidized bed drying process are combined in a drying tower, the dryer can be operated within a wide range of particle size, moisture content and dry air temperature.So as to better control the degree and effect of particle polymerization or granulation.

There are three areas in the drying tower where atomized droplets interact with dry particles until the cohesive or granulating structure is completed.

1. The first area is around the atomizer: atomized droplets and atomized droplets are in contact with each other.

2. The second area is inside the drying tower: atomized droplets and dried particles contact each other.

3. A third area within and above the fluidized bed: wet and dry particles in contact.

The greater the contact between the droplet and the particle, the larger and more compact the resultant cohesive or pelletized particle.

The fine coalescing powder was obtained at a higher air temperature, at which time the moisture content of the particles in the drying tower was lower and the coalescing effect was less.Use cooled air in a built-in fluidized bed.

The larger cohesive powder is obtained at a lower air outlet temperature to increase the moisture content of the particles in the drying tower, thereby increasing the effect of cohesive and granulating. Heated air is used in the built-in fluidized bed.

It is possible to convert the feed liquid into larger cohesive and granulating particles and to obtain a finer powder that is normally available in other spray drying equipment.

It is also possible to manipulate the rewetted cohesive particles as powder feed.

The product application

Chemicals: detergents, dyes, fertilizers, inorganic and organic salts, pesticides, tannins, etc

Medicine: analgesics, antibiotics, plasma, enzymes, vitamins, etc

Polymer: e-pvc, styrene, UF, PF resin, etc

Food: coffee, dairy products, egg products, condiments, maltodextrin, soup, vegetable protein, yeast, etc

Advantage:

1. Free flowing powder is produced during coalescence forming or granulation

2. The generated powder contains a very small amount of dust (referred to as dust-free particles).

3. Can dry many other equipment can not be processed thermoplastic and hygroscopic products.

4. As the temperature of particles is always kept low during the whole drying process, it is an ideal drying equipment for heat-sensitive products

5. Drying is completed at a lower exhaust temperature, which is conducive to efficient use of energy.

Operation mode:

The liquid feed, which may be solvent, suspension or emulsion, is pumped to the atomizer (spray gun) located in the air distributor at the top of the tower.

The atomizer atomizes the liquid into a high-speed dry air flow, and the atomized liquid droplets generated are driven downward by the airflow to the built-in fluidized bed, and are dried into particles at the same time.

At the same time as the particles enter the fluidized bed, the airflow moves upward in reverse direction and is discharged from the top of the drying tower.

Fine particles separated from the exhaust air are recycled back into the drying tower.

Fluidized bed particle fluidization fine powder circulation and particle movement in dry air occur in an air environment with higher dust density than traditional drying system.Particles with high moisture content can be processed to overcome the problem of surface adhesion.

The moisture content of the particles entering the fluidized bed can be controlled to a certain extent to obtain larger particles and structural changes (cohesion or granulation)

When necessary, the final drying and cooling of the product can be carried out in an external fluidized bed connected to the internal fluidized bed outlet.

Difference between upper exhaust and lower exhaust spray drying tower:

In general, according to the form of drying tower exhaust, can be divided into the upper tower exhaust drying tower, tower body expansion exhaust drying tower, tower cone bottom mouth large curved tube exhaust drying tower.According to the dust collecting forms of the tower, it is divided into eccentric bag dust collection, circumference bag dust collection, single (two) stage cyclone dust collection, single (two) stage cyclone dust collection, cyclone and bag dust collection, cyclone and bag dust collection, and cyclone and bag wet dust collection and spray drying tower.Among them, eccentric bag dust collection and circumferential bag dust collection drying tower are connected with the tower body.At the same time, the drying tower can also be equipped with fine powder adhesion, multi-spray gun adhesion granulation, finished products wind transport and vibration fluidized bed system or equipment.In order to improve the operation safety of the equipment, explosion-proof door and ultra-high temperature alarm device are installed in the tower.Automatic control system can be provided for users with higher requirements.According to the drying characteristics, evaporation and heat source of different materials, the design accords with the product drying process.

1. According to the movement direction of hot air and materials, the lower exhaust tower is the downstream drying mode, while the upper exhaust tower is the change of mixed flow drying, which is the difference between the two.Therefore, the advantages of the pressure upper exhaust spray drying tower over the lower exhaust tower lie in:

1) energy saving: since the return air chamber of the upper exhaust tower is in the high negative pressure area of the tower on the upper part, in the process of evaporation, high negative pressure evaporation reduces the evaporation temperature, which saves steam and energy.Evaporation of 1kg of water in the upper exhaust tower only consumes 2.8-3.0kg of steam, saving 8-10% of steam;

2) saving construction investment: the height of the upper exhaust tower is 5 ~ 7m lower than that of the lower exhaust tower with the same size of equipment.

3) good product quality: the particles of the upper exhaust tower powder are uniform, while the larger particles and smaller particles are few.Because the dry area of powder is high negative pressure area, dry powder is low temperature drying, so that the powder in a variety of vitamin damage, protein is not denaturing.In addition, the heating time of the powder in the drying process is shorter than that of the exhaust tower in the high temperature area, which makes the powder have better color, particle size and impact adjustment.

4) easy cleaning: the tower structure is simple and convenient to manufacture.Due to the direct connection between column and cone of the tower, each Angle connection is smooth and excessive, and there is no dead Angle when cleaning. After opening the tower door, each part in contact with dust can be easily cleaned.

5) reduce sewage discharge and energy saving and reduce labor intensity: no annular air curtain can be formed in the downdraft tower, and the tower wall hanging powder is serious, so the tower must be painted every day.Brush tower increases material loss and wastes a lot of hot water.It not only consumes energy but also increases the amount of sewage discharged.And wind towers on the drying is mixed flow drying, spray process is a constant rate drying period for downstream, slow down period for mixed flow row of wind, the wind reached the bottom of the form 180 g, make the drying of material and air separation, the wind in the rapid upward movement in the tower wall form a large circular air curtain, formed the circular wind curtain dry tower, the control tower wall hanging powder phenomenon, can wash a tower more than 10 days, thus reduce the emissions, and save energy, and reduce the labor intensity of workers.

Equipment features:

It is an ideal choice for the mass production of dust-free, free-flowing and instant aggregate particle products.The average particle diameter adjustment range (D50) of the polymer products was 0.1-0.35mm.The adjustment range of bulk density of polymer products (0.35-0.6)g/ml;Can produce direct tablet medicine, health care products particle products: can control the particle powder in the whole drying process to maintain a low temperature, suitable for a wide range of heat sensitive products production;Thermoplastic, high fat content, viscosity and moisture absorption of the products are ideal and effective for a long time continuous production;The drying is carried out at a lower exhaust temperature, and the energy efficiency is 10-15% higher than the traditional spray drying equipment.Flexible modular design, complete sets of equipment according to the actual needs of customers convenient combination;The equipment structure is compact and only needs relatively small equipment installation space, which greatly reduces the cost of drying tower workshop.

Operation mode:

Atomization characteristics of nozzle: high-pressure nozzle atomization, atomizing Angle and atomizing pressure can be selected according to the material viscosity and atomizing droplet diameter;The Angle between different nozzles of multi-nozzle structure can be adjusted to produce products with high degree of agglomeration and low degree of agglomeration.Protection of low-temperature air flow around atomizing nozzle;Drying tower: the hot air flow at the center of the hot air mouth at the top of the drying tower is vertically downward at high speed. It is fully mixed with atomized liquid droplets at the center of the hot air mouth to enhance the heat transfer effect.The hot air jet diffuses to the bottom of the cone of the drying tower and flows back upward, separating the dried particles from the air. In the upward movement of air, the annular air curtain is formed on the wall of the tower, separating the wet powder from the wall of the tower and preventing the deposition of sticky powder on the wall of the tower.Fine powder is winnowed into the fine powder separator from the side outlet of the top of the tower;The particles fall to the inner fluidized bed at the bottom of the tower.Built-in fluidized bed: the material in the built-in fluidized bed can be dried/cooled under stable and uniform low temperature and low humidity.Greatly reduce the dry tower cone material deposition.Fine powder is easier to produce dust-free particle products.Vibrofluidized bed: the fluidized drying and cooling of the product is carried out to obtain the dust-free particle product with the specified moisture content and temperature conditions.The fluidized form adopts the piston flow to make the product get uniform drying and cooling treatment and maintain the consistency of product properties.Vibration motor frequency and excitation force can be adjusted to control fluidized drying/cooling time.Fine powder reflux adhesion: the fine powder separated from the air is sent to the atomization area of the drying tower through positive pressure wind, and it collides and sticks with liquid droplets and wet particles to form cohesive particles.The fine powder can be sent to the built-in fluidized bed or vibrated fluidized bed.

Product application:

Multistage fluidized bed spray drying equipment is an ideal drying equipment.Material properties: high fat content, poor thermal stability, thermoplastic, easy moisture absorption and high moisture content viscous products;Dairy products, microencapsulated essence, coffee, vegetable powder, flavoring, yeast, health care products, protein and proteolytic products, etc.Antibiotics, vitamins, enzyme preparations, blood products, sugar products, all kinds of fermentation liquid products;Dye, pesticide, inorganic matter, organic matter, tannic acid, molasses, water treatment agent, etc.

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