Main factors affecting the puffing effect of SUNSHINE Industrial Wet Puffing Machine

Extrusion puffing technology integrates material transportation, mixing, high temperature, high pressure, and high shearing, and performs physical, chemical or biological treatment on materials. It has a short action time, small loss of nutrients, and a wide range of applications. In order to give full play to the production capacity of the puffing machine, ensure its output and the quality of the puffed materials, it is necessary to understand the factors affecting the puffing effect. However, there are many types of puffing machines and variable factors affecting the puffing effect. Now let's analyze and discuss the wet puffing machine.

The influence of puffing process on the puffing effect

1. Raw material processing

The materials must be processed before entering the puffing machine to remove impurities such as metal, stone, mud, etc. in the materials to prevent impurities such as stone and metal from causing wear or breakage to the spiral blades, extrusion screws, pressure rings, etc., and at the same time improve the quality of the product.

2. Crushing

Soybeans, corn, etc. need to be crushed by a crusher before puffing. The particle size of raw materials determines the surface area of the feed composition. The finer the particle size, the larger the surface area, and the faster the material absorbs moisture in the steam, which is conducive to conditioning and improves the quality and output of puffing. However, the finer the crushing, the higher the power consumption. Generally, the crushing particle size is about 3mm. Raw materials such as glutinous rice do not need to be crushed and can be directly puffed.

3. Feeding

In order to maintain the quality of the puffed product and the puffer to work at full load continuously and evenly, the material flow entering the puffer must meet the puffing needs. Special attention should be paid to effectively eliminate the uneven feeding caused by arching and other reasons in the puffing bin. Insufficient feeding will result in unsatisfactory puffing effect; excessive feeding will easily block the machine, resulting in reduced productivity or even "burning the machine".

4. Conditioning

(1) Conditioning steam

During the conditioning process, an appropriate amount of steam should be added, and the quality of the steam will also affect the quality of conditioning. If too much steam is added, the material will become too soft when puffing raw materials such as soybeans, and the extrusion force in the puffing chamber will be insufficient, affecting the puffing effect. The amount of steam added is generally 7%~8%; when puffing raw materials such as corn, the viscosity of the material will increase, thereby increasing the difficulty of discharging and affecting production efficiency. The amount of steam added is generally about 10%. If insufficient steam is added, the gelatinization degree of the material will be poor, difficult to shape, and the puffing effect will be unsatisfactory.

For feeds with different formulas, the amount of steam added during conditioning is also different. For materials with more starch, more steam needs to be added, and for materials with higher protein content, the amount of steam added should be controlled. The steam supplied should maintain a stable pressure to prevent condensation. The working pressure of the boiler should be maintained at 0.6~0.8ma, and the steam pressure before being transported to the conditioner should be adjusted to 0.058~0.4MPa. Dry saturated steam should be used to avoid the use of wet steam.

(2) Tempering time

Steam-water conditioning requires a certain amount of time to increase the temperature and moisture content of the material and promote starch gelatinization. Different formulations correspond to different conditioning times to meet the needs of producing feeds with different formulations. For most powders, the temperature is generally controlled between 80 and 90°C and the humidity is 16% to 18%. When the moisture content is high, the adhesion is better, but too much moisture will block the die holes and the cost of drying will also increase. Adjusting the angle of the paddle can change the conditioning time. The paddle can be adjusted to a smaller angle to give the powder a smaller deflection effect; or the paddle can be adjusted to a flat angle to make the material transported along the shell to achieve a larger deflection effect. However, the spiral direction of the blade must follow the "first in, first out" principle as required. In addition, a positive overflow plate can be added to the conditioner to stop the material from moving forward, so as to make more use of the space in the conditioner, increase the filling coefficient of the material in the conditioner, and then increase the efficiency of heat and moisture conversion into the material, extend the conditioning time, and achieve the best conditioning effect.

5. Extrusion

In the wet extruder cavity, the material is extruded through the annular gap between the extrusion screw, the pressure ring and the extrusion cavity. The annular gap is the main factor affecting the degree of maturation and output of the material. The smaller the configuration of the extrusion screw and the pressure ring, the larger the annular gap, the smaller the temperature rise of the material, and the larger the output. Therefore, under the premise of ensuring the extrusion temperature (without affecting the degree of maturation), the diameter of the extrusion screw and the pressure ring can be reduced to improve the productivity of the extruder.

The size of the die hole also affects the output of the extruder. The larger the die hole, the greater the output of the extruder. The small die hole has a large extrusion resistance, resulting in a large back pressure and a large power consumption. Therefore, without affecting the extrusion parameters and product quality requirements, the use of a template with a large die hole can improve the productivity of the extruder.

The influence of raw materials on the extrusion effect

The bulk density, particle size, composition (starch, fiber, protein, fat, etc.), moisture content, etc. of the raw materials will have an impact on the extrusion effect. The amount of water in the raw materials and the temperature of the tempering water are closely related to the quality of the expanded product, processing stability and the pressure state in the expansion chamber. When the water content is low, the energy consumption is high and the output is also reduced, and vice versa. When the water content is similar, steam conditioning has higher output and lower power consumption than cold water conditioning. If the raw material has a high oil content or too much oil is added during the extrusion process, it is easy to cause sliding wall idling, so that the extrusion force on the material does not meet the requirements and the material cannot be fully expanded. At this time, the amount of material added should be appropriately increased, the diameter of the pressure ring should be increased, or the diameter of the die hole should be reduced.

When the starch content in the raw material is high, the temperature adjustment and steam addition should be appropriate, otherwise it is easy to cause machine blockage, thereby affecting production efficiency. In particular, if too much material is added at the beginning, it is easy to cause machine blockage, thereby affecting the continuous production. After extruding the raw material with higher viscosity, it is best to clean the expansion chamber with a material with a higher oil content (such as soybean powder) to maintain its good working characteristics.