Water replenishment measures of pellet feed

Moisture index is one of the key indexes of pellet feed quality, and its economic benefit to feed factory is self-evident. Imagine a pellet feed processing plant with an annual output of 40, 000 tons. If its moisture index is 1% lower than the control target, the direct economic benefit loss for the whole year can reach more than 1 million. At the same time, it will also bring some other negative effects, such as the increase of dust during feed processing, the increase of powder content in particles, the increase of energy consumption in granulation, the unsatisfactory gelatinization of corn, the wear of granulation ring mold, the decrease of feed palatability and so on.

There are many reasons for "water damage" in feed factories. Such as:

(1) microrespiration of food crops during storage.

(2) impact, friction and suction in the process of comminution.

(3) selection of process parameters in the process of quenching and tempering and granulation.

(4) Parameter selection of cooling section.

Therefore, the moisture control of finished products is a complex and systematic work. In this paper, several common water replenishment methods are summarized for reference and study only.

(1) adjust the theoretical moisture of the finished product by using high moisture raw materials

Before the formula is put into production, the theoretical moisture of the finished product can be estimated according to the detected moisture of the raw materials used. If the theoretical moisture of the finished product itself is very low (2) adding water to the mixer

When the moisture content of the mixed powder is less than 12.5%, you can consider adding water in the mixer. The mixer should pay attention to the following points when adding water:

1. Atomized water must be added, and the amount of atomized water should not exceed 2% of the material (the actual water retention is estimated to be less than 50%), otherwise it is easy to mildew.

2. Adding liquid anti-mildew agent, but it has a certain effect on palatability.

3. Pay attention to the residue in the equipment such as mixer and finished product sieve, and clean it regularly (it is reported that there are small particles sifted out at the sieve of the finished powder).

Disadvantages: mixing uniformity, equipment residue, mildew, palatability.

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It has been reported that the moisture content of the finished product can be increased by 0.4% 0.6% by spraying 1% 100 ℃ of hot water at the entrance of the conditioner. At present, there are similar molding products on the market: water flash evaporator, compared with the mixer to add water, this method should have an advantage in controlling mildew.

> (4) Steam pressure control

As for livestock and poultry feed, the commonly used boiler steam pressure is 6-9kg/cm2, and the pressure before quenching and tempering is 2-4kg/cm2. The higher the pressure, the higher the steam saturation and the lower the humidity; conversely, the lower the pressure, the higher the humidity and the higher the steam water content. In order to meet the production needs, a lower boiler gas supply pressure (5-6kg/cm2) can be selected and controlled at 2-3kg/cm2 before quenching and tempering, and it is best to install a pressure reducing valve after the steam drum in the workshop to stabilize the pressure.

Disadvantages: when changing the formula, the steam pressure may need to be adjusted repeatedly in order to achieve different quenching and tempering conditions.

(5) increase the quenching and tempering temperature

After quenching and tempering, the more suitable moisture is controlled at 15-17%. If the moisture is low before quenching and tempering, the moisture can be increased by moderately increasing the quenching and tempering temperature. Some studies have pointed out that under certain conditions, when the temperature increases by 10-15 ℃, the moisture can increase by 1%.

Disadvantages: arbitrarily change the tempering temperature required by the formula, it is possible to increase the nutritional loss of the formula.

> (6) increase quenching and tempering time

There are two ways to increase the quenching and tempering time: 1, reduce the quenching and tempering speed; 2, adjust the blade angle of the modulator: the contact area between the material and steam can be affected by adjusting the blade angle, and the fullness of the modulator can affect the moisture of the material.

(7) close or adjust the steam trap in the steam supply pipeline

The purpose of installing the trap is to remove the condensed water from the steam pipe and improve the quality of the steam. In the case of low moisture in the semi-finished product, it can often be reversed: adjusting or closing the trap will not cause machine blockage, but will help to increase the moisture content of the product.

> (8) reduce the compression ratio of ring mode

The thickness of the ring die affects the resistance of the material passing through the ring die. For the ring mold with a certain aperture, in the process of granulation, generally speaking, the greater the thickness, the greater the friction resistance, and the higher the friction temperature, the more moisture loss. Therefore, in the case of ensuring the appearance quality and powder content of the product, moderately reducing the ring mold compression ratio is also conducive to the increase of moisture.

> (IX) Regulation of cooling air volume

Under the premise of ensuring the cooling effect of the product, it can be adjusted through the following aspects: (1) appropriately reduce the height of the material level; (2) adjust the size of the throttle; and (3) control the speed of the fan through frequency conversion technology.

The moisture regulation of finished products is a complex and systematic project, from raw material procurement, storage, production and processing to finished product storage, it is necessary to establish moisture control points in each link. In order to obtain the ideal moisture of the finished product, the key is to effectively monitor the moisture control points and choose effective improvement methods. Zhou Xiaoquan