Questions regarding the selection of compressed air pipe diameter
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The issues I’m currently unsure about are as follows: 1. The pressure in our company’s system is 0.8 MPa, but Baidu suggests that the flow rate should be between 10–15 or 15–20 m/s. Moreover, it is stated that the higher the pressure, the lower the flow rate. Why is that? 2. The unit of flow rate for this reduced pressure is standard cubic meters. My current demand is 2000 Nm3/h; so how can I convert this value to determine the pipe diameter? What is the relationship between pressure and volume? 3. Is there anyone who has an Excel spreadsheet or a small app with direct calculations for this? If so, could you send it to 36653170@qq.com? I would be extremely grateful...
Convert the volume under standard conditions to the volume under operating conditions, and determine the pipe diameter based on the flow velocity
For simplicity, just use the ideal gas law – it has little impact.
Actual volumetric flow rate: 2000/9 = 222 m3. Pipe cross-sectional area: 222/3600/10 = 0.00617 m2
When selecting the pipe diameter, it is essential to take into account the transmission distance, as such transportation is definitely fully turbulent. The pressure drop is proportional to the square of the flow velocity; the longer the transmission distance and the higher the flow velocity, the greater the pressure drop will be. Calculate it yourself; create an Excel sheet and compare several pipe diameters to find out. . .
According to the recommended values in the process design manual, indeed a higher pressure implies a lower recommended flow rate. This is because compressed air at high pressures has a higher density, which leads to more severe wear on the pipes; therefore, it is better to use a lower flow rate. As for the unit of measurement, it is a mass unit; you need to calculate the volumetric flow rate based on the actual density at 0.8 MPa. The recommended flow rate of 15–20 is determined based on your piping system; for main pipes or secondary pipes, a higher flow rate of 20 m/s is generally chosen, and it’s fine to use a higher flow rate for pipes that lead to equipment. It is mainly based on economic considerations
Well, I know that now, thank you