Xing Zhaoliang Li Tie Ni Chunlin Choline Choride is chemically known as 2-hydroxyethyl-trimethylamine hydrochloride with a molecular formula of C5H14ClNO and a molecular weight of 139.63. The structure of choline chloride is shown in Figure 1.
Choline chloride is divided into two states, liquid and powder. In this paper, we studied the drying process of 50% of the carrier powder choline chloride (a powdery material obtained by mixing 70% choline solution with bran, corn cob and suede carrier). Carrier bran, corn cob, and mink contain starch and protein colloid. These materials will swell the starch particles after impregnating the aqueous solution of choline chloride, and the swelling will occur at a temperature of 60-80 °C during the drying process. Gelatinization causes the material to bond into a block; while the protein colloid gels at this temperature due to its hydrophilic action, which also causes the material to bond. The synergistic effect of starch and protein colloids sometimes causes the dry material to form a plastic block that cannot be pulverized, damaging the production equipment, making production impossible. How to avoid the gelatinization of starch and how to avoid gelation of proteins or destroy their gelation is the key to selecting the drying process conditions.
1 Production process of domestic powder choline chloride drying and its existing problems
1.1 In the 1980s, manufacturers generally used ovens or ovens to dry them. The materials were often knotted and needed to be crushed before they could be used. The quality of the products could not be guaranteed. The materials were easily gelatinized and deteriorated, and even burned, which brought great problems to safe production. The single-machine processing capacity of the drying system is small and cannot meet the requirements of large-scale production. The production environment is poor and the labor intensity of workers is also high.
1.2 Drying powder choline chloride with wok, high energy consumption, small output, poor labor conditions of workers, high labor intensity restricts the promotion of the equipment.
1.3 Tube bundle dryer Dry powder choline chloride, the material tends to adhere to the outer wall of the heat exchange tube during the drying process, causing the material to be gelatinized and the product quality is not good. The small amount of single processing of the drying system cannot meet the requirements of large-scale production. The typical process is shown in Figure 2.
1.4 Airflow dryer Dry powder choline chloride, the material in the airflow tube during the drying process is easy to stick to the wall and catch fire, resulting in a safety accident. The cyclone is easy to stick to the wall, the system is difficult to operate for a long time, and the single-machine processing volume is small, which cannot meet the requirements of large-scale production. The typical process is shown in Figure 3.
1.5 pulverized cyclone dryer dry powder choline chloride, the material in the gas flow tube is easy to stick to the wall during the drying process, causing a safety accident. The single-machine processing capacity of the drying system is small and cannot meet the requirements of large-scale production. The cyclone dryer is easy to stick to the wall and the system is difficult to operate for a long time. The typical process is shown in Figure 4.
1.6 Rotary flash dryer Dry powder choline chloride, the equipment handling capacity is small. The material is easy to stick to the wall and accumulates in the cone portion of the flash dryer, causing the equipment to not operate normally for a long time. The typical process is shown in Figure 5.
1.7 Dry dryer powder choline chloride, the equipment handling capacity is small. The material is easy to stick to the wall and accumulates on the top of the dryer, causing the material to gelatinize and deteriorate, even burning. The typical process is shown in Figure 6.
1.8 Fluidized bed dryer Dry powder choline chloride, most of which can run under 500 kg/h. The single-machine processing capacity of the drying system is small, which cannot meet the requirements of large-scale production, and it is necessary to regularly clean the air distribution plate of the fluidized bed and remove the particulate materials in the bed. During the drying process, the material is easy to smash and agglomerate, and needs to be broken after drying. The typical process is shown in Figure 7.
2 Determination of the drying process plan The above-mentioned powder choline chloride drying process generally has the disadvantages of small processing capacity, low reliability and high energy consumption. After a technical and economic comparison of various drying methods and review of a large amount of literature, it was determined to use a secondary self-cleaning rotary cylinder dryer to dry 50% powder choline chloride. The typical process flow is shown in Figure 8.
The production process has been successfully applied to several domestic choline chloride drying projects. The indicators obtained after long-term production practice are as follows: 1 annual output of the product > 10,000 tons; 2 moisture of the powder before the drying of choline chloride; 2 powder moisture after drying choline chloride 0.97%; 4 dryer barrel The speed of the motor is 3 r/min; 5 the inlet air temperature is 160 °C; the 6 exhaust air temperature is 80 °C; and the system steam energy consumption per ton of product is ≤ 0.92 t.
3 Conclusion The choline chloride production process has the following advantages.
1 Solve the problem of material deterioration and even fire caused by choline chloride crust during drying process, and the safety and reliability of the system are greatly improved.
2 Solved the problem that the quality of the product could not be guaranteed due to the adhesion of the material, and the quality of the product reached the international level.
3 The material in the whole production process is basically operated in a closed state, which greatly improves the pollution problem of the odor.
4 The system's energy consumption is greatly reduced, saving costs.
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