Resistance issues in methanol transport pipelines
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It is transported from the methanol raw material storage tank to the plant’s tank area via a shielded pump (Q=80 m3/h, H=40 m). The pipeline is made of seamless steel tubes with a diameter of DN150; the transmission distance is approximately 800 meters, with 35 90° elbows and two ball valves along the way. According to the calculations done by the design institute, the pipeline resistance is over 0.6 Mpa; the tank before the pump is not pressurized, and the institute stated that the pump would not be able to overcome this resistance. However, in actual operation the pump functions fine, with a flow rate of up to 65 m3/h. Is it the pipeline resistance value that is incorrect, or is there some other issue with the calculations?
It was confirmed with the design institute that the pipeline resistance calculation is indeed 0.6 Mpa
This post was last edited by bfdlwolf on 2015-12-18 at 10:53. The calculations done by the design institute were incorrect; when selecting the pipe diameter, it is necessary to ensure that the resistance loss per 100 meters of the pipeline does not exceed 50 KPa. However, the results obtained by the design institute showed that the resistance loss per 100 meters for this pipeline exceeded 50 KPa, which indicates either that the pipe diameter was chosen incorrectly – too small – or that the calculations performed by the design institute were flawed. The flow velocity in this pipeline is not high (flow rate of 80 m3/h, flow velocity of approximately 1.3 m/s), which indicates that the pipe diameter chosen is appropriate. In fact, based on calculations, the total pressure drop across this pipeline is approximately 0.11 MPa. (Pipe inner diameter 150 mm, methanol viscosity: 0.5945 MPa·s, flow rate 80 m3/h)