Potato Flour Processing Line For Potato Plant Extract Processing

Technical description

1. Washing

The raw potatoes come via a belt conveyor into the rod de-soiler of the washing plant. The potatoes then arrive into the cyclone-destoner, where an upward stream makes the potatoes float, while heavy parts such as stones and clods sink. A special stone conveyor seizes these separated heavy parts, lifts them out of the water and drops them in a container.

A flume transports the product with circulation water in a washing machine with two compartments. separation of circulation water washing In the first compartment, the potatoes are separated from circulation water. The potatoes then enter the washing compartment, where a bar-type drum immersing 10 to 15 cm into a water bath with its special internal components thoroughly moves and rubs the potatoes so that even loam comes off easily.

10-15 The potatoes are then sprayed with water. This technology does not require any additional water for potato cleaning purposes, but uses process water only. The washed potatoes are transferred into a hopper for intermediate storage.

2. Waste water treatment

Wastewater from the cyclone de-stoner and the washer gathers in the tank for wastewater. A special pump transfers the wastewater to two sand sedimentation tanks (one stand-by). The overflow gathers in the canalization to be provided by the buyer.

3. Friction

Friction peeler is specialized for removing the skin of potato, potato dermabrasion barrel in the tray with potatoes autobiography rotate and move up and down only dermabrasion barrel produced relative movement of friction, so as to achieve friction peeled effect.     

The aircraft batch access to materials, all the movements and time are controlled and setted by PIL, small and ultra-small production line friction peelers more economical and convenient.

4. PIL Peeling

The charges get into a hopper. A screw conveyor serves to reclaim the product, evens it and feeds it into the dry de-skinner. In the front part of the skinner, thorough and suitable surfaced rolls remove the loose potato skin. A pump discharges the mushy skin, which is used as high quality animal feed.

A screw conveyor serves to deliver the potatoes through the machine, the speed of which (and consequently the retention time) is variable.

A downstream washing machine washes skin residues and dissolved potato cells off the potato surface.

From the washer, the peeled and washed potatoes get onto an inspection belt conveyor, where they are sorted by hand and, if necessary, trimmed. Rejected potatoes get into separate containers and are also used as animal feed.

5. Pre-cooking and cooling

An inspection belt conveyor transfers and feeds the peeled potatoes through a distributor into the slicing machines. Here the potatoes are cut into slices to allow definition of heat transfer during the pre-cooking process.

The thickness of the cut can be adjusted.

Then the potatoes are pre-cooked in a warm water bath. The pre-cooker is of a steam injection screw type.

Why this is done: (1) provides for gentle gelatinization of the starch, without impairing the cell membranes as a result of the large volume. (2) changes the intercellular cementing substance in such a way that the cells separate more easily after cooking.（3）prevents enzymatic discoloration of the product.

A lifting wheel separates the potatoes from the pre-cooking water and feeds them through a flume into a screw-type cooler, where they are cooled in a water bath.

The result of this is the retro-gradation of the starch gelatinized in the pre-cooking stage. Retro-gradation in turn reduces the amylose solubility. Even if in the downstream cooking and separating processed potato cells should be destroyed, thus releasing starch, the retrograded starch can hardly give the end product a sticky texture.

6. Wet hopper

A special belt conveyor feeds the product directly from the cooler in to a wet hopper.

In normal operation, the wet hopper can hold product, protected with water containing a small quantity of dissolved SO2. When there are changeovers and shutdowns, it also takes up product from upstream machines.

7.  SO2 Cooking

The product is discharged from the wet hopper via a water lock and transferred hydraulically. A vibrating screen separates the potato slices from the conveying water, which flows back through an equalization tank into the hopper. A balance provided in the downstream belt conveyor measures the mass flow rate, which is set by varying the speed of the product feeder.

Via a final lock, the belt conveyor feeds the product into a screw type cooker, where it is cooked at atmospheric pressure in steam or vapor.

The cooker used is a screw type unit, injecting steam just above the machine bottom and the screw shaft to provide a uniform temperature in the product and consequently homogeneous cooking.

Efficient removal of condensate makes sure that the water content of the cooked product only increases just slightly.

The optimum cooking time must be determined empirically and will have been reached when the cell-cementing substances have been weakened to such a degree that the cells separate with no major destruction of their membranes.

8.   Mashing

From the screw type cooker the cooked potatoes drop down directly into the mashing screw conveyor, which gently pushes them through a perforated template for mashing. Additives are added and mixed with the mash in a downstream screw conveyor, which feeds it to the drying plant.

9.  Drying

A single drum drier is employed to dry the mash.

The unit comprises an internal steam heated drying drum, six non-heated surface treated applicator rolls and the necessary bearings. A common chain drives all the applicator rolls. A frequency converter allows the speed, and consequently, the drying time to be varied.

The drying temperature is kept constant indirectly by controlling the pressure inside the drum. In the applicator roll contact zones, potato cells are transferred to the drying drum to which they stick to form a layer, increasing in thickness from one applicator roll to the next. This layer dries completely as the drum rotates and eventually comes off by itself or with the aid of a scraper.

The fact that the layer is in intimate contact with the heated surface for the whole process results in a very short drying time, which is a major factor influencing the quality of the dried end product.

Furthermore, the single drum drier acts as a separator. Any non-cooked potato fragments and impurities are not transferred to the drum, but remain in the rotating layer on the applicator rolls. This layer is separated at specific intervals and transferred to the next applicator roll.

On the lowermost or last applicator roll, the material is rich in unacceptable waste, which a screw conveyor feeds into a waste container.

A fan removes the vapor produced by the drier through a hood and the roof into the open air.

10. Pre-breaking and conveyance

The layer formed on the drum drier comes off like a web of paper, which a special screw conveyor collects, tears and feeds to a pre-breaker attached at its end. This unit roughly breaks the dried product layer to such a degree that is it suited for pneumatic conveyance. The design of the injector is such that the air stream does not entrain wet and heavy parts, but let them drop through into a waste container.

The good product enters a separator, removing the conveying air and is then fed to a breaker.

11. Breaking

A fluidized-bed breaker gently breaks the material to the required flake size, at a very low percentage of fines and free starch. Under the breaker are two collecting tanks, which are selected alternately. These tanks receive the production of 3 to 4 hours, allowing product samples to be examined during that time.

12. Pneumatic conveyance

The finished product is fed from the breaker to the silo.

13. Silo

The size of the finished product silo is such that it can hold the quantity produced over a period of at least 20 hours. Useful volume is approx. 2 x 20m.

14. Bagging

Where the product is consumed, or subjected to further processing, within 6 weeks from production as a maximum, inertiation may be dispensed with, in case PE-lined multiple kraft paper bags are used for packing.

Normal packing weight is 12,5 or 25 kilo bags.

12.525/Bagging, bag closing and palletizing are manual processes.

15. Process additives

The production of flakes requires monoglyceride to be added to the process in the form of an emulsion, modifying the starch from the product to give the mash a non-sticky fluffy texture.

16. SO2 system

To protect the surfaces of raw potatoes and potato slices during the preparation processes, water containing a small percentage of free sulphur dioxide must be used so as to prevent enzymatic browning and the Maillard reaction and to inhibit germination.

The concentration is subject to the officially allowed percentage in the end product.

Addition proper into the process is in the wet hopper.

17. Electrical

For plant control a central control system is accommodated in a separate electrical room.

The control equipment consists of a complete PC system. Special graphic displays provide the operator with all necessary information about the condition of the plant. Interactive keyboard and/or mouse operation acknowledges or modifies operating parameters and modifies, monitors and controls the operating state.