The raw materials need to be crushed in two steps. The first step is coarse crushing, such as peanut cake and shrimp head shell. The raw materials need to be crushed into coarse powder by a 400 hammer bean cake crusher, and the screen is 3 mm; The second step is fine grinding, which can use ultra-micro pulverizer or 50-type hammer pulverizer, and the latter should be equipped with a sieve with a mesh size of 0.5 mm The pulverization must meet the requirements of 40 meshes and 80% passing through 60 meshes.
? Second, the raw materials of the batching process must be cleaned up before crushing, such as hammers, scraps of paper, wood, stones and other sundries. Before the second crushing, ingredients such as peanut cake powder, fish powder, blood cell protein powder, squid powder, etc. Mix according to the formula proportion. Pulverize into powder of more than 40 meshes, and then add standard flour, additives, etc. And stir evenly, and the coefficient of variation is not more than 10%.
? Thirdly, the moisture content of crushed raw materials is generally about 65438 03% during conditioning, and the materials are not easy to soften and gelatinize during granulation, which has an impact on granulation and water resistance, so proper moisture addition is another important condition to ensure powder bonding and starch gelatinization. Firstly, when stirring, use a high-pressure water pump to spray water for a few minutes to make the water content of the powder reach about 18%; Then steam is added. In this way, the water content is uniform and the material meets the softening requirements. After adding steam, the temperature of the material rises rapidly, the gelatinization time of the material is prolonged, the starch is fully gelatinized, the working temperature of the mold is correspondingly reduced, and the service life of the mold is prolonged. When the material temperature after steam treatment reaches 90- 105℃, the treatment effect is good, and the steam pressure should be controlled between 4- 15 kg/cm2 and kept stable.
? The produced feed is dark brown with smooth surface. The granules are consistent in length, delicious and attractive. If the temperature after steam treatment is lower than 80℃. The granules are yellow and white, there are many powders, the water resistance is poor, and the shrimp is anorexic because the feed is not completely gelatinized and cooked. Like a sandwich board. When the discharge temperature exceeds 105℃, the granulation turns black and has good adhesion, but the nutritional components are destroyed greatly, and the shrimp is anorexic and difficult to digest. The amount of water added should make the water content of the material about 17%- 18%. Generally, after steam quenching and tempering, the material is taken from the material taking hole of the main engine, held in the hand, and cracked with a little vibration. When the water content is too small, the gelatinization speed is slow, the granulating current is large, the granules are irregular, and the yield is reduced; Too much water will easily make the granulator slip and block the die hole. The steam addition in actual operation is limited to the fact that the granulator does not slip and block the die hole.
The conditioner of shrimp feed host is different from that of livestock feed, and it should be lengthened. Usually, two kinds of conditioners are used to make steam permeate the material evenly, so as to soften and gelatinize starch. The main engine ring die has been used for a long time, the inner diameter is worn and the bell mouth is deformed, which affects the normal granulation or blocks the die hole. The lower ring die should be removed, and the powder in the die hole should be washed out and soaked in oil to make the inner wall of the hole smooth; If the inner wall of the ring die is seriously worn, the inner wall should be polished and the bell mouth should be reworked. It is best to use original ring mould for imported machinery. The diameter of shrimp feed particles is preferably 2-25 cm. Crushing young shrimps and processing them into 0.3-0.6 mm particles.
Fourthly, after the particles are extruded by the dryer, the moisture content is high and it needs to be dried, which can be dried by electric heating or steam. Its function is to reduce the water content of granular materials, usually below 10%, to ensure that the feed does not deteriorate for more than 2 months; Secondly, it promotes re-gelatinization, plays a post-ripening role and increases the cohesion of granular materials.
The temperature of hair dryer is generally 90℃, and the particle passing time is about 20 minutes. If the temperature exceeds 90℃ or the drying time is too long, the granules may be burnt and the vitamins will be destroyed, thus affecting the shrimp's food preference and complete feed. The temperature of steam drying can be relatively increased to 65438 005℃.
5. The cooling of cooling particles is usually carried out in a cooling tower. The exhaust fan is used to suck in a large amount of cold air and take away the heat and part of moisture of pellets in the tower. Cooling the pellets to normal temperature of about 65438 0℃, and packaging.
If the particles directly enter the cooling tower without being treated by the dryer, the surface of the particles will be rapidly cooled and dehydrated inside, and a large number of fine cracks will be generated on the surface and spread to the depth, even the fine particles with good gelatinization will appear the above phenomenon. When feeding, soaking in water will break down into several pieces along the cracks, making the water resistance worse. If dried, the above phenomenon will be much less. The moisture content of the granules is 17%- 18% when they leave the granulator, 12%- 13% after drying and10/after cooling.