Five calculation factors in dilute phase pneumatic conveying
? ? ? in designpneumatic conveyingWhen dealing with these five factors, it is important to pay attention to the calculation of productivity, the wind speed of conveying materials, the calculation of conveying air volume and pipe diameter, the calculation of pressure loss, the pressure loss caused by material acceleration, and the pressure loss at bends and other pipelines. By calculating these factors well, the conveying efficiency of pneumatic conveying will be greatly improved.
1、 Calculation of productivity
? ? ?When designing pneumatic conveying equipment, it is essential to calculate the main parameters and select them correctly and reasonably. Only in this way can the equipment operate normally and reflect the rationality and progressiveness of the overall design of pneumatic conveying. These parameters include productivity, mixing ratio, wind speed, air volume, conveying pipe diameter, pressure loss, fan efficiency, etc. The calculation and determination of productivity is an important basis for equipment design and selection. Calculate the maximum conveying capacity of pneumatic conveying per unit time based on the workload of the project.
2、 Calculation of mixing ratio
? ? ? To calculate productivity and/or pneumatic conveying equipment, the following main parameters must be calculated and determined. The correct calculation and reasonable selection of these parameters not only ensure the normal operation of the equipment, but also reflect the rationality and progressiveness of the overall design of pneumatic conveying. These main parameters include productivity, mixing ratio, wind speed, air volume, conveying pipe diameter, pressure loss, fan efficiency, etc. The calculation and determination of productivity is one of the main criteria for equipment design and selection. Calculate the annual transportation capacity, annual working days, and daily work shift system according to project requirements. Calculate the maximum conveying capacity of the pneumatic conveying system per unit time. Wind speed for conveying materials
3、 Airflow velocity of material conveying
? ? ?In pneumatic conveying systems, air moves in pipelines to achieve the highest economic speed for conveying efficiency. Firstly, this speed ensures that the transported material can flow smoothly through all sections of the conveying pipeline. If the speed is too low, the increase in resistance coefficient will increase friction, causing pressure loss and exacerbating pipeline wear. At the same time, the wear of elbows will also be severe, leading to a shorter service life. Therefore, the selection of conveying speed is related to the operational performance and economic benefits of pneumatic conveying devices.
4、 Calculation of conveying air volume and pipe diameter
? ? ?The calculated air volume for pneumatic conveying refers to the effective air volume required to transport materials under normal pressure, with a temperature of 20 ℃ and a relative humidity of 50%. When choosing a fan, consideration should also be given to air leakage in the conveying system. Generally, a margin of 10% -20% should be increased. When calculating the inner diameter of gas pipelines, the required air volume should be taken into account, without considering the leakage coefficient. When the conveying distance is long, the flow velocity of the same pipe diameter varies greatly, so a variable diameter pipeline system can be used.
5、 Calculation of pressure loss
? ? ?The energy required during pneumatic conveying is mainly consumed by the pressure loss caused by the movement of air and conveyed materials in the conveying pipeline. At present, in the design of pneumatic conveying, the commonly used empirical formula to calculate the pressure loss of two-phase flow in the conveying pipeline mainly includes the following parts:
1. Pressure loss of air and materials in horizontal and vertical conveying pipelines.
2. Pressure loss caused by material acceleration.
3. Pressure loss fittings at bends and other pipelines.
4. Pressure loss caused by compressors, connecting pipes, and noise reduction equipment.
5. Pressure loss caused by material gas separation, dust removal equipment, feeders, suction nozzles, etc.