Dewatering and Drying System

The section of dewatering and drying has come to final steps of cassava processing, the vacuum dehydrator can remove as much moisture as possible and the flash dryer can dry the wet starch to the low moisture content of no more than 13% to achieve the starch storage standard. The hydraulic press can remove as much moisture as possible and the cassava dewatering machine can roast the wet Garri to the low moisture content of no more than 13% to achieve the Garri storage standard.

1. Vacuum filter: Drum filters or vacuum filters have been used for dewatering various slurries including starch slurry in the starch processing system. As the drum rotates, it is partially submerged in the feed starch slurry. The vacuum draws liquid through the filter medium (cloth) on the drum surface which retains the solids. The vacuum pulls air through the cake and continues to remove moisture as the drum rotates. If required, the cake can be washed to remove impurities or to extract more product.

Finally, the cake is discharged from the drum to a conveyor or chute to the next process step. The filtrate and air pulled through the medium flow through internal filtrate and pass through the rotary valve and into the filtrate receiver. The liquid stream is separated from the vapor stream in the receiver. The liquid filtrate is then pumped to the next step in the process.

The vacuum filter is widely used for the dehydration in starch, modified starch, medicine, food, chemical industry etc, low energy consumption, small area, friendly operation, and stable running.

2. Hydraulic press: Load the bags directly on to a hydraulic press. Under control of the hydraulic station and electric cabinet to lift and press the jack handle up and down until it becomes hard to move. Repeat the process several times each day until no more water comes out of the bag to produce a firm wet cake.

3. Flash dryer: Flash drying is defined as the drying of particles that are suspended and conveyed in a hot air stream. Drying starch using a flash dryer is the most economical drying method. The whole process is fully automatic requiring no handling or human involvement. The feed rate is adjusted automatically as per the variation in moisture content in wet cake thereby achieving consistent product quality.

The principle of Flash Drying is to evaporate surface moisture instantaneously. It is well-known fact that the surface area of wet lump increases as the size of lump decreases. The wet cake is disintegrated into fines to increase the surface area.

4. Garri fryer: Roasting be done mechanically using an automated Garri fryer made of stainless steel material and with electricity, natural gas, firewood or charcoal as the heat source. The finished product (Garri) is usually recognized from the color change from white to cream (for non-palm oil fortified Garri) and crispy hand feel of the grains/particles.