Feed Equipment Knowleagde

With the high development of the feed industry, a large number of hammer mills have been selected by feed mills, but there are many problems in use. Now I will simply analyze the main factors affecting the performance of hammer mills for Everyone's reference.

The main factors affecting the working performance of the hammer mill are divided into three categories: the crushed material, the crusher itself and the supporting equipment.
1. Influence of crushed materials
Different types of raw materials have different seed structure and physical properties, and the degree of difficulty in pulverizing them is also different. Therefore, the power consumption of crushing unit weight materials varies. Usually, corn, sorghum and other concentrates are easier to smash, and roughage is more difficult to smash, because the crude fiber has high crude fiber content and toughness, and only shearing effect is better. In addition, loosely structured raw materials are more easily comminuted than structurally dense particles.
The effect of the moisture content of the raw materials. According to the relevant experiments, when the grain is based on 14% moisture, the water content increases, and the yield decreases as follows: water increases by 1%, yield decreases by 6%; moisture increases by 2%, yield decreases by 8%; moisture increases by 3%, yield decreases. 10%; water increased by 4%, yield decreased by 12.5%; water increased by 5%, yield decreased by 15%. In addition, when the water content is high, the screen hole is easily blocked in the pulverizing chamber, the effective sieving area is lowered, the yield is lowered, and the equipment is rusted and corroded.

2. The impact of the pulverizer itself
2.1 The effect of the end line speed of the hammer
According to domestic and foreign data, the optimum hammer line speed varies with the physical and mechanical properties of different materials. According to the introduction, when using 5.2mm aperture sieve plates, the optimum line speed of several common materials is as follows: sorghum - 48m /s; corn - 52m / s; wheat - 65m / s; rye - 75m / s; barley - 88m / s; oats - 105m / s; bran - 110m / s; —115m/s; speed up, increase productivity, make the particle size thinner, too fast, increase the no-load power, increase the vibration and noise. In actual production, the application of the pulverizer is diversified and requires versatility. According to the experience of experiment and use, the hammer line speed of the hammer mill used in China is more than 80~90m/s.
2.2 Impact of hammer thickness and density
According to relevant data and tests, when the rotor rotates at high speed, the hammer is agitated in the material, as if a number of cutters and hammers are too thick, the efficiency is not high, but it is too thin and easy to wear, so it is based on performance in China. For the price ratio, a rectangular hammer of 5mm or 6mm is generally used. The number of hammers on the rotor has a large influence on the pulverizing ability, and the number of each hammer is obtained by orthogonal test. And measured by the density of the hammer. In China, low density is used for coarse pulverization and high density is used for fine pulverization.
2.3 Impact of hammer screen clearance
The hammer sieve gap refers to the distance between the end of the hammer and the inner surface of the sieve plate when the rotor rotates as shown in Fig. 2. It directly determines the thickness of the material layer of the crushing chamber. The material layer is too thick, and the friction coarse crushing effect is weakened. The crushing may block the mesh hole and not easily pass through the mesh hole; if the material thickness is too thin, the material is too easy to pass through, which has an influence on the crushing granularity. The size of the gap depends mainly on the diameter of the mesh and the type of material to be pulverized. It has the best hammer screen clearance for certain materials and mesh openings.
2.4 Influence of the size and shape of the mesh
The test proves that with the increase of the mesh hole, the production efficiency of the hammer mill is also improved. For example, the mesh hole is increased from 1mm to 1.5mm, the production efficiency is increased by more than 40%; from 1.5mm to 2mm, the production efficiency is improved. More than 50%; from 2mm to 3mm, the production efficiency is increased by more than 50%. Of course, the mesh hole is enlarged and the finished product becomes thicker, and the relationship between the mesh hole diameter and the crushing fineness is generally: the average particle size of the finished product (mm) = (1/4 to 1/3) mesh diameter (mm).
The shape of the mesh also affects the pulverization efficiency and the pulverization quality. If the fish scale hole and the punching round sieve are used, the fish scale has a high output, but the cost is high, the average grain size of the finished product is large, and the rotor cannot be used in the reverse direction. According to the performance price ratio, the punching circle is slightly Dominant.
2.5 Influence of sieve plate installation
The sieve plate generally used in the feed mill is a perforated circular sieve. It has a matte surface (flare) and a glossy surface. We recommend that the matte surface (flare) be installed inside. This is because in the direction of the flow, the material is prevented from passing over the sieve hole, so that the material collides with the corner of the bell mouth when passing through the sieve hole, which can both pulverize and increase the screening ability.
2.6 Influence of sieve area and opening ratio
The productivity of the hammer mill is limited by the ability of the sieve plate to pass through:
G=vFρ(t/h)
Where: G - productivity (t / h);
V——the average speed (m/s) of the airflow product as it passes through the screen;
F——effective sieve area of ​​the sieve plate (m2);
Ρ—the bulk density (t/m3) of the airflow product as it passes through the screen.
It can be seen from the above formula that the area of ​​the sieve plate is increased, the opening ratio of the sieve plate is increased (the effective sieve area is increased), thereby increasing the hourly productivity of the pulverizer. According to reports, when F increases by 9%, G can increase by 35%, and power consumption is reduced by 13%. The power consumed on the sieve plate accounts for 85% of the total power of the mill.

3. Impact of supporting equipment
3.1 Impact of incoming material flow
Feed conditions are critical to the normal operation of the hammer mill. If the flow rate is unstable, the operating current of the drive motor will fluctuate, affecting the normal operation of the main motor. Therefore, the feed of the hammer mill must be continuous and uniform to ensure the full performance of the main motor.
3.2 Influence of discharge method
The discharge mode of the pulverizer has a relatively large impact on the working performance of the pulverizer. The discharging device must discharge and transport the pulverized material in time to ensure continuous operation; at the same time, it is required to improve the working performance of the pulverizer, low cost, less dust and low noise. At present, there are generally two ways of discharging the hammer mill, one is mechanical discharge, and the other is pneumatic negative discharge. The production practice proves that the mechanical discharge is suitable for coarse pulverization (mesh diameter of 1.5mm or more), and the pneumatic negative pressure discharge is suitable for fine pulverization (mesh diameter of 1.5mm or less).
3.3 Influence of the fan
Whether it is mechanical discharge or pneumatic negative pressure discharge, it is necessary to equip the fan, and the fan mainly provides the main parameters of the air volume and the wind pressure. The air volume ensures the wind speed and output of the pipeline and keeps a certain amount. The balance, wind pressure to ensure that the resistance loss in equipment and pipelines is overcome and a certain margin is left to ensure that the crusher below the sieve plate is minus 1,000 to 1,500 Pa. In other words, the choice of a reasonable fan has a greater impact on the output of the mill.
3.4 Pulse effects
Pulses mainly appear during use: 1 The solenoid valve does not work or the diaphragm leaks, which causes the bag to be cleaned, so that the wind network resistance increases, affecting the output of the vertical shaft micro-grinder; 2 the bag is damaged or blocked, and the bag is damaged. The concentration of the discharged dust is exceeded, and the blockage of the cloth increases the resistance of the wind network, which affects the output of the vertical shaft type micro-pulverizer.
In short, the output of the hammer mill, the particle size of the finished product, the uniformity of the finished product size, etc. are determined by a combination of factors. Therefore, when we encounter specific problems, as long as we calm down and comprehensively analyze, we will be able to find a solution.