As the competition in the feed market becomes increasingly fierce, the quality of pellet feed has received more and more attention. Users require that feed pellets have a smooth appearance, uniform pellets, appropriate pellet hardness, low pulverization rate, and moisture content that meets standards. The realization of these requirements involves many aspects such as feed formula and raw material quality, feed processing technology, and equipment.

Impact of production process equipment

1 Influence of steam system

(1) Small feed mills often use low-pressure steam boilers. The steam pressure used is generally 0.2~0.4MPa. The steam boiler is also placed near the pelletizer. Due to its low output and short steam pipeline transportation distance, the pelletizer ring mold The pore size is small (generally ø2~ø3), so the particle quality is better;

(2) Due to the high output and large number of equipment in large feed factories, the steam boilers are generally located far away from the production workshop. Therefore, the steam transmission pipelines are long (usually several hundred meters), and high-temperature and high-pressure steam is often used to ensure smooth operation during pelleting and tempering. Steam quality. Generally use 0.8MPa and 180°C saturated steam.

Judging from our experience, the steam boiler should be placed near the granulator and the length of the steam pipeline should be shortened as much as possible, especially in the north: In addition, oil furnaces should be preferred for steam boilers, because it is difficult to ensure the stability of steam pressure in coal furnaces. Otherwise, the moisture content in the steam will be high and the steam pressure will be unstable, which will affect the conditioning effect and the quality of the particles.

2 Influence of conditioner

The length of the conditioner of a pellet mill (8t/h) used in a feed factory in the north is 1.4m. Due to the increase in the variety of alternative raw materials added to the feed in recent years, coupled with the cold winter weather in the north and the long transportation pipelines, If the conditioning time is too short and the conditioning temperature is low, it is difficult to guarantee the conditioning effect. Therefore, the conditioner used in the pellet mill of large feed factories in the north should be of the enhanced type to ensure the conditioning temperature and time of the powdered feed, thereby ensuring the quality of the pellet feed.

3 Influence of granulator ring die and pressure roller

Mold gap: The gap should be guaranteed to be 0.05~0.3mm, that is, when the ring die rotates, it can just drive the pressure roller to rotate. When the gap is large, the ability of the wedge-shaped space between the die rollers to grab feed decreases, and the die roller squeezes the feed. When the pressure is less than the frictional resistance of the inner wall of the die hole to the feed, the granulator will block and affect the quality of the granules.

When replacing ring dies or pressure rollers, it is generally required to replace them in pairs. During normal production, the die gap must be adjusted before each shift. When using old ring dies and pressure rollers, they should be polished to ensure their surfaces are as smooth as possible.

Pressure roller wear: When checking the granulation, if it is found that the pressure roller is not rotating smoothly, it must be replaced in time. Generally, when the pressure roller bearing is damaged, the pressure roller often cannot rotate normally. Otherwise, the machine will be blocked and the granules will be affected. quality.

Die hole diameter and feeding cone hole: When the thickness of the ring die remains unchanged, if the die hole diameter decreases, the extrusion strength of the feed pellets will increase, the pellet shape will be neat, the hardness and density will increase, and the powdering rate will decrease. According to data, feed pellets with die holes of ø2~ø3mm are beneficial to the raising of suckling pigs and chicks. Of course, the reduction in the diameter of the ring die hole will inevitably lead to a reduction in production efficiency and an increase in energy consumption. Therefore, the above factors must be considered to make a reasonable selection.

In addition, if the feed cone hole of the ring die is severely worn, the output and pellet quality of the granulation production will decrease. Because the amount of steam added to the feed is limited at this time (large amounts of steam will cause machine blockage), thus reducing the feed conditioning temperature. Therefore, if the ring die is still available, the feed cone hole of the ring die should be processed in time to ensure output and particle quality.

4 Effect of cooling and particle size

(1) Particle cooling should be uniform and moderate. Counterflow coolers are now more commonly used, with high cooling efficiency and good effects;

(2) The main attention for particle crushing equipment is that when the teeth of the crushing roller are blunted, they should be repaired in time. Otherwise, the squeezing effect of the crushing roller will become stronger, the uniformity of the feed particles will become worse, and the pulverization rate will increase. During normal production, the gap between the crushing rollers must be correctly adjusted according to the type of feed;

(3) After the pellets are crushed, a plane rotary classification screen with a small screen surface inclination angle should be used for screening, especially in large feed factories. When the screen surface inclination angle is too large, the pellet materials will not be screened adequately, resulting in The powdering rate of pellets increases.