Mar. 17, 2021
In the process of feed processing, raw material cleaning is one of the important sections.Impurities in raw materials not only affect the quality of feed products, but also cause damage to processing equipment, causing abrasion of parts, reducing service life and affecting production.Therefore, a correct understanding of cleaning process and equipment can ensure product quality and smooth production.
Design of cleaning process
1、Choose cleaning equipment reasonably according to the characteristics of raw materials. Due to the difference between granular raw materials and powdery raw materials in fluidity and sieving ability, granular raw materials usually choose cylinder pre-cleaner, powder raw materials choose conical powder cleaner or plane rotary screener, and cake raw materials usually choose conical cleaner.
2、Determine the capacity of cleaning equipment according to the production scale of the workshop. Usually the production capacity of cleaning equipment is about 30% larger than the production scale;
3、When choosing cleaning equipment, try to use small volume, conveniently screen-changing, good sealing and high efficiency equipment;
4、Ventilation and dust removal should be considered in the process design to ensure the workshop environment and health;
5、According to the principle that is beneficial to the efficiency of cleaning equipment, the position of various cleaning equipment in the process must be reasonably arranged. Such as magnetic equipment is usually placed after the pre-cleaning equipment.
Selection and use of cleaning equipment
There are three kinds of cleaning equipment commonly used in feed mills: grid screen, pre-cleaner and magnetic equipment.
The grid screen is generally placed at the feeding mouth, is the first stage of the cleaning process. Its main function is to initially clean the large sundries in the raw materials, and protect the following sequence conveying equipment and personal safety of dumping workers.
The gap of grid screen should be based on the geometric size of the material, corn and powder side material should be about 30 mm, for the cake class raw material gap should be about 40mm, and should ensure that there is a certain strength. Usually welded with 2 ~ 3 mm thick, 10 ~ 20 mm wide flat steel or 10 mm round steel. In the installation should be fixed, and to ensure that there are about 8° ~ 10° angle, in order to facilitate the bag material dump, reduce the labor intensity of the dumping workers.
In the process of use, should be timely clear up the sieved large miscellaneous, so as to effectively achieve the purpose of preliminary cleaning.
The pre-cleaner is the main equipment in the cleaning process, it is used to clean the non-magnetic impurities in the raw material. Its performance and process parameters directly affect the cleaning effect. Due to the differences in physical properties between granules and powders, such as fluidity and sieving capacity, different pre-cleaner should be used for different raw materials.
SCY series cylinder pre-cleaner is widely used for cleaning granular raw materials because of its high output, small power consumption, simple structure, small footprint, convenient screen change and other characteristics.
SFJH type series plane rotary screener is used for powder material cleanin. The screen body is flat type. Its movement combines circle, elliptic motion and linear reciprocating motion, increased the screening process. So its output is large, efficiency is high, power consumption is small. The screener is equipped with the screen surface cleaning device at the same time. Replacement screen body, from the above, which can effectively prevent the mesh plug, reducing the area.
In the selection of pre-cleaner should pay attention to the following points:
(1) According to the physical characteristics and geometric size of the raw material to choose the appropriate mesh;
(2) Often check whether the screener cylinder or screener surface is intact, otherwise it will affect the cleaning effect;
(3) Should be equipped with adjustable dust and air suction volume. Under normal circumstances, the suction volume of each initial cleaning screen is not less than 50m3/h, and a disc valve is installed in the appropriate position of the suction pipe to facilitate the air volume regulation;
④ Enough production capacity should be guaranteed.
Permanent magnet cylinder has the advantages of simple structure, small volume, flexible installation, low price, no power, iron removal efficiency up to 99%, so it is widely used, but it needs to manually clean impurities on a regular basis.
In the selection of magnetic equipment should pay attention to the following points:
(1) In order to prevent large impurities into the magnetic equipment and cause blockage, generally should be installed after the pre-cleaner;
(2) The permanent magnet cylinder should be installed in the vertical chute pipe, and the height of the vertical chute above it is not less than 400 mm, so as to prevent the deviation of materials and affect the effect of iron removal;
(3) There are certain requirements for material velocity and thickness in the pipe with magnetic box installed. General material flow speed should be controlled within 0.1 ~ 0.12 m/ s, the material thickness is different because of the difference in the flow, the granule should be controlled in about 10mm, the powder is about 6mm;
(4) The magnetic impurities adsorbed in the magnetic separation equipment should be cleaned regularly, and the impurities removed should be treated in time to prevent them from entering the material again;
(5)should choose the one with sufficient production capacity.
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