Referring to the particle size of carbon black for rubber, we have to mention a breakage rate. Breakage rate refers to the fraction of powdered carbon black into the process. The content of this powder also needs to be controlled. Generally, the size of carbon black is more than 125 m, which is called grain. The size of powder is less than 125 m. We say the lower the breaking rate of carbon black, the better. So what on earth has affected the crushing rate? We are going to study the problem today.
From the form of Kerrey's movement in the air flow, the particle size and direction of the particles vary in size and content because of the difference in size and content. The velocity and direction of the particles will change, and the velocity difference between particles is obvious, and the difference between the particles is produced. The friction and collision of birth. Even if the size, quality and shape of carbon black particles are identical, they will have different crushing rates when they are moving at different locations. The reason is that there are differences in axial velocity, mirror speed and circumferential velocity in some locations.
Besides, different types of carbon black will break their own rates. Some research departments have done similar experiments to experiment with different kinds of carbon black under the same transport condition, and the total breaking rate is very different.
And it's the particle properties of carbon black. The particle density, crushing strength, particle size and particle shape of carbon black will also affect the breakage of carbon black. The bulk density of particles varies mainly from the carbon black process produced by different manufacturers. Carbon black to prevent the length of time will also affect the size of the accumulation of density, the longer the time, the absorption of water will increase the density of carbon black accumulation, the greater the density of accumulation, the greater the transport resistance, the more difficult transportation. For carbon black with great resistance to transmission, to increase conveying speed, larger conveying pressure and more air consumption will be used. With the increase of air volume, the mixture ratio of gas and fuel will decrease, reduce the resistance of conveying and increase the conveying speed, which will cause the breakage rate of carbon black to increase.
The crushing strength of carbon black, the greater the crushing strength of the carbon black particles, the smaller the increment of the crushing rate is, the greater the crushing strength of the carbon black particles in the condition of the same transportation distance, pipeline arrangement and transportation parameters. In order to ensure that the crushing rate of carbon black particles is less than 5% after transportation, the crushing strength of carbon black particles should be greater than 25g for the pneumatic conveying system with the distance greater than 100m, and the crushing strength of the carbon black particles should not be lower than that of 22~24g if the transport distance is less than 100m carbon black particles.
In terms of particle size distribution, the effect on crushing rate is mainly based on the size effect of strength. Generally, the measured values of material strength vary with the size of the experimental particles. The smaller the particle is, the greater the value of its strength is, and the less likely it is to fracture during transportation. The greater the particle size, the greater the possibility of defects, and the more cracks it contains.
One thing that needs to be noticed is the hygroscopicity of carbon black. If carbon black is stored in the atmosphere for too long, the carbon black is easier to caking when it is transported, affecting the transport capacity and the residual amount in the pipeline. In order to achieve normal transportation, it is necessary to increase the conveying speed and speed, which will inevitably cause the breakage rate of carbon black to increase. In addition, when the carbon black is involved in cleaning the conveying pipeline, the cleaning rate will increase the crushing rate of carbon black.
The influence of pneumatic conveying system on the breakage rate of carbon black mainly includes three problems: the length of pipeline, the speed of conveying and the pressure of conveying. First, the length of the pipeline, the size of the transport resistance and the probability of collision and friction between the carbon black particles and the pipe wall are one of the main factors affecting the crushing rate of carbon black. Conveying pressure is another important parameter in pneumatic conveying process. The greater the difference between the initial pressure and the end pressure, the greater the pressure drop, which leads to the end of the pipe, especially the elbow, which tells the running particles to have a great impact on the elbow, which has a great negative effect on the rate of ion breakage. At the same time, the wear of pipes, especially elbow, is also very unfavorable. In addition, if the pressure fluctuates at every point in the pneumatic conveying process, it will also lead to the increase of broken particles. Of course, if the pressure of the sending tank is too low, it will lead to dilute phase transportation, not only the consumption of air will increase, but also the transmission capacity will drop. Therefore, it is the best choice to choose the right data through experiments. Finally, the speed of conveying, the speed of transporting carbon black has great influence on the crushing rate. Generally speaking, the lower the transmission capacity is, the better delivery speed can solve the big problem in order to ensure the production efficiency.