Why can’t the pipeline flow increase?
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The existing process wastewater and waste oil are mixed together and then incinerated; they are combined using a mixer in the furnace before being burned. The waste oil pump and the wastewater pump are installed 100 meters away from the furnace head; they are of the same model, with a flow rate of 2 m3/h and a head of 25 m. The parameters for wastewater and waste oil are as follows:**Sample Information | Analysis Items | Remarks**
--- | --- | ---
Density | Viscosity (25°C) |
Wastewater | 1.0004 | <10 mPa·s; viscosity is below the lower limit of 10 mPa·s as measured by the viscometer
Waste oil | 0.8828 | 10.8 mPa·s
**Number of Elbows | Number of Ball Valves (including check valves) | Pipe Diameter | Pressure after Pump | Pressure before Static Mixer | Actual Flow Rate**
--- | --- | --- | --- | --- | ---
① Waste oil pipeline | 30 | 6 | DN20 | Around 0.25 MPa, or even lower; less than 0.2 MPa | 40 Kg/h
② Wastewater pipeline | 26 | 4 | DN25 | 0.3 MPa | 0.3 MPa | 450 Kg/h
At present, due to the low pressure of the waste oil, it is not possible to increase the flow rate into the mixer. It’s unclear why the pressure of the waste oil has dropped so significantly; the actual flow rate of waste oil is much lower than that of wastewater, and the flow velocity is also much lower. In terms of pipe resistance, the pressure drop in the wastewater pipeline is greater than that in the waste oil pipeline (I’m not sure if I’ve made a calculation error). Could there be an issue with the dimensions of the waste oil pipeline? I would appreciate some guidance from experts.
1. Where do the figures of 40 kg/h for the used oil pipeline and 450 kg/h for the wastewater pipeline come from? ? Is there a mass flow meter on the pipeline? ? 2. Pump selection: 2 m3/h × H25 m. The outlet pressures for the oil waste and wastewater pumps are 0.25 MPa and 0.3 MPa respectively; so what is the actual flow rate? You need to check the performance curve of the pump. 3. Only by knowing the actual flow rate can the pressure drop be calculated, which explains why the pressure drop in the waste oil pipeline is so high.
At the mixer inlet, both wastewater and waste oil are equipped with mass flow meters; according to the pump’s performance curve, the head pressure at 40 Kg and 400 Kg is almost the same. But in actual operation, the outlet pressure of the pump is such that the used oil is at a lower level than the wastewater
The density of used oil is lower than that of wastewater~~~
Try to reduce the mixed pressure as much as possible!
Check whether the mixer structure is reasonable.