Complete mechanical equipment for cassava starch processing production line
5. Cyclone washing and refining:
A small amount of insoluble protein, 0.2-0.3% soluble protein and other minerals remain in the white starch milk, which will seriously affect the quality of starch and make its deep processed main products such as syrup, glucose, medicine, textile and other products fail to meet the quality standards.
The cyclone unit is composed of nine units connected in series and mainly consists of three working chambers, dozens to hundreds of cyclone tubes and slurry pumps. Starch milk enters at high speed from the tangential inlet at the upper part of the cyclone tube. Due to the centrifugal force of high speed rotation, solid particles fall to the bottom with the spiral flow. After being discharged and mixed with the overflow water of the next stage, the solid particles enter the cyclone of the next stage to be pushed in order to push the class. Clear water (40℃ soft water is used according to the normal requirements) is added to the last stage. Its working sequence is the backward side of the first stage of starch and the forward side of the next stage of washing water to form countercurrent washing, so that the product reaches the national standard.
The protein content is the main index for testing the quality of starch. The protein content exceeding the standard directly affects the application range of starch. For example, if glucose injection is used, starch with too high protein content will have mildew and white spots. Therefore, reducing the protein content in starch production is the key process.
Most of the starches produced by indigenous methods use the launder method of pool precipitation to remove protein, i.e. it occupies a large factory site and cannot accurately control the protein content. It can only be based on experience. Therefore, the production volume and starch quality are restricted. The disc separation and cyclone washing process we are now adopting completely solves the above problems. After the secondary protein separation, a certain amount of white matter can be added for full reaction to improve the whiteness of starch. Enter the cyclone unit and add a certain amount of clear water to completely separate protein and starch. The separation of primary and secondary discs is connected with a transfer tank in the middle of the cyclone unit to form a continuous operation process.
Disc separator is a kind of high-precision equipment, requiring trained personnel with a certain degree of education to operate it. After each operation, it should be cleaned. For specific operation procedures and methods, please refer to the Operating Instructions for Disc Separator.
6. Starch Dehydration:
At present, starch dehydration equipment can be divided into three categories: one is a three-legged feeding and discharging centrifuge, which has a high degree of labor. Second, the automatic scraper centrifuge, although operated automatically, consumes a large amount of electricity (30KW) and has expensive accessories (about 10,000 yuan per year). Thirdly, the vacuum rotary drum dehydrator equipped by our company at present consumes less power (8KW), is all stainless steel equipment, has low rotating speed (about 9-12 rpm), is not easy to damage, saves about 70% of energy saving effect compared with similar products, and is convenient to operate.
Before use, the vacuum rotary drum filter dehydrator rotates in the air and then puts in starch slurry. when the thickness of starch absorbed on the filter cloth surface of the machine is 5-6mm, adjust the scraper to scrape off starch. At the same time, keep starch with a thickness of 3-4mm on the filter cloth, adjust the pulp feeding speed and observe the dehydration effect. If the humidity of the material is too high to slow down the rotation speed of the machine, the dehydration effect will be better. Generally, the moisture content of dehydrated wet starch is better at about 39%, if the moisture content is high, the drying difficulty will increase.
It should be noted that the vacuum dehydration filter needs to be operated by professional personnel. Generally, it should not be disassembled randomly. When the equipment is running for a period of time, it should be cleaned in time to prevent acid substances from corroding the filter cloth. Dehydrated starch can be directly dried in a dryer.
The airflow collision dryer uses coal as fuel, and the hot airflow enters the heat exchanger, making the clean air entering the heat exchanger at the other end become dry hot air, which is sent to the drying tower to be mixed with wet starch with water content less than 40%, vaporizes the water in 2-3 seconds, and is discharged through the separator.
The drying tower adopts positive and negative pressure two-stage drying, wet air is discharged from the first stage, and air with higher temperature is discharged from the second stage, and enters the feed pipe for reuse. Compared with single-stage drying, energy can be saved by 20-40%.
The feeding conveyor adopts stepless speed change and can be adjusted arbitrarily according to different climates and materials.
The heating system is equipped with an automatic temperature control device, which can set the temperature of dry hot air at will according to needs and keep a certain temperature all the time, thus achieving stable and consistent starch quality.