Drying equipment for the dye industry

At present, there are two types of drying equipment used in China's dye industry: the first type is the drying equipment introduced from abroad in the early years, and the second type is the drying equipment designed by China itself and the backward drying equipment left over from the early years. Compared with the old dyestuff plant drying equipment technical level gap, both more advanced equipment and more backward. And newly built dyestuff factory equipment is generally better. From the perspective of development, after China's accession to the WTO, the export volume of textiles will increase significantly, dye production is also increasing. In addition, dyestuff manufacturers are decreasing year by year, but the output is increasing, which indicates that the production scale of a single variety of dyestuff is expanding, which leads to the development of drying equipment towards the direction of large scale. Take spray drying as an example. Ten years ago, most of the evaporation water was less than 200kg/h, and the diameter of the dryer was no more than 3m. Now, the diameter of the equipment can be up to 6m and above, and the evaporation water is about 1000kg/h. The diameter of the flash dryer also reaches 1.4m, and the evaporation water quantity is above 800kg/h. The formation of monopoly production of a single variety of dyes and the continuous expansion of production scale objectively promoted the development of drying equipment towards the direction of large-scale.

In recent years, people focus on the development of drying equipment to the development of the direction of the combination of drying machine, trying to optimize the combination of the existing dryer, to play the advantages of each dryer. The combined multi-stage dryer has the following advantages over the single stage dryer:

(1) Combination dryer is easier to save energy;

(2) Combination dryer is easier to ensure product quality, drying process can also be classified, crushing and other operations, the heat sensitive material can be timely cooling;

(3) more flexible operation, according to the specific rules of material drying for a variety of drying machine scientific combination.

The combination of dryer has the following aspects roughly:

(1) Combination of various drying methods of the combined dryer, such as spray - fluidized dryer;

(2) Combined with a variety of heat transfer process of the combined dryer, such as film - fluidized bed dryer;

Multistage combination of the same type of dryer, such as multistage air dryer, etc.

However, the drying equipment manufacturing problems are also more, mainly equipment manufacturers do not understand the processing technology of dyes. Dyestuff drying is an operation process with strong technicality. There are many kinds of raw dyes and their commodity indexes are complex. In recent years, dye drying has become more and more difficult. For example, in the past, most of the commodity disperse dye strength required 100%, now requires 200%, which means that the amount of additives in the reduction of the heat resistance of the dye also declined. If the processing formula is not good quality, drying will be more difficult.

The drying equipment factory often needs the dye factory to provide the physical and chemical indexes of the materials to be dried. If the dye factory has no corresponding experience, the parameters provided are difficult to ensure the most appropriate. This brings trouble to the design and manufacture of dryer. The author has seen some unsuccessful examples, seemingly equipment problems, in fact, is the designer of the dye drying process parameters do not understand, should strengthen the study of drying process.