Dye Spray Dryer

Commonly used drying equipment in the dye industry

Drying is a very important unit operation in the production of dyestuffs, because drying is not only a simple solid-liquid separation process, but more importantly a process in the production of dyestuffs, and the quality of the product and the type of dosage depends on the level of drying technology and the comprehensive use of equipment in many cases.From the economic point of view, the dryer is expensive and the project investment is large. However, drying is a high energy-consuming process, the thermal efficiency fluctuates within the range of 15-80%, and the operating cost of the equipment has a very close relationship with the design and selection of the dryer, so the decision makers of the dyestuff factory have always attached great importance to this.There are many varieties of dyestuffs, more than 450 kinds of dyestuffs are produced frequently, and their physical and chemical properties are very different. Even the different production process of the same species, the different product requirements of the same species, resulting in drying conditions may be different, so it causes the complexity of drying.

The drying of dyestuffs is therefore more technical than for other products.

1.Pressure Spray Drying

Pressure spray dryers (also known as spray drying towers because the equipment is tall and tower-shaped) are most commonly used in dye drying.Because the product of the pressure spray dryer is in the form of particles, the average particle size can reach about 150~200mm.It does not require the addition of dust preventive agents in the product to prevent dust, and its flowability, wettability and other application properties are superior to those of powder.So it is popular among users.This also establishes its dominant position in dye drying.Structural design is to ensure that the performance of the dryer to achieve a good state, easy to operate and maintain.

The structural design of the dryer includes:

Tower header design,These include air inlet types,Inlet duct diameter,Rectification type,Number of Rectifier Plates,Ratio and spacing of openings,Upper Cone Height,Inclination, etc.Drying chamber opening design,Openings should be designed for ease of operation,Good airtightness, no accumulation of material, no sticking to the wall.This includes access holes,Temperature, pressure, speed holes, sight glasses, nozzle holes, etc.

Tower base design,The bottom of the tower should be designed in such a way as to ensure a certain degree of gas-solid separation.Mainly includes determining the height of the lower cone, inclination angle, discharge type, exhaust type and exhaust pipe size, etc.

In addition, the design of cleaning devices, such as air sweeping, air hammer, electric hammer, etc..The design of the pressure spray dryer should pay special attention to the relationship between the hot air inlet temperature of the dye and the residence time of the material.

2.Centrifugal Spray Dryer

Centrifugal spray dryer plays more and more roles in dye drying, especially the evaporated water volume of the dryer using centrifugal spray drying is more common.Centrifugal spray drying mainly depends on the atomizer, this atomizer has rotating parts, the liquid through the high-speed rotation of the centrifugal force generated by the atomizer so that the material is atomized in an instant, so it is called centrifugal spray drying.Centrifugal spray dryer tower body is short, L/D ratio is 0.9:1~1:1, compared with the first two kinds, it can greatly reduce the height of the plant, there is no high-pressure equipment and high-pressure pipeline in the system, which brings a lot of convenience to the manufacture and installation of equipment.Production elasticity, centrifugal atomizer production elasticity, processing capacity in a wide range of still have good atomization effect.Centrifugal atomizer is mainly nozzle line speed to ensure the atomization of the material, through the adjustment of the atomizer line speed can easily get different particle size of the product.Atomizer nozzle aperture is large, the work is not easy to be blocked by the material, the material filtration is not so strict.

For the above reasons, centrifugal mist dryer is more widely used, and is widely used in the drying of many dyes, pigments and dye auxiliaries. Centrifugal spray drying design should determine the relationship between the rotary speed and tower diameter.