l have a pump rated at 4m3/h and 35m head. lt pumps edible oil through an economizer and the to dearator with some nozzles. From the dearator there is another pump feeding a vessel (rated 9m3/h and 40m head) and there is a flowmeter reading 1800L/h (1.8m3/h). Some how the dearator gets empty or starved with oil. My question is how so as the dearator pump is just pumping 1.8 m3/h from the dearator, while the one feeding it is feeding at a rate of 4m3/h. see attached schematics
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pumps
- Thread starter Thuba
- Start date
If you are measuring 1.8 m3/hr on the second pump then that is what the flow really is. Your pumps may be rated for 4 and 9 m3/hr but how much they really pump has to do with the pressure loss at a given flow in your system. This is where the system curve intersects the pumps curve.
For the first pump the pressure loss/drop in the system is the piping, economizer, and loss thorough spray nozzles. The loss through the spray nozzles are the greatest as they need a certain high pressure upstream to flow a given flow by converting the upstream pressure to kinetic energy/velocity, so although your pump may be rated for 4 m3/hr at 35 m, it may actually be operating at 50 m due to loss through the nozzles at 1.8 m3/hr flow. So it is pumping 1.8 m3/hr since the downstream pump can only be pumping what is input into the deaerator by the first pump
Likewise your second pump rated at 9 m3/hr at 40 m might be operating at a much higher pressure drop versus flow in the downstream piping system. In this case it may also be operating at say 50 to 60 m discharge pressure at 1.8 m3/hr. This is you have a piping system with a high pressure drop or the downstream vessel you are pumping into is a high operating pressure.
In any case both of your pumps are operating at the measured flowrate of 1.8 m3/hr at a high point (low flow) on your pump curve due to high losses in the piping system.
For the first pump the pressure loss/drop in the system is the piping, economizer, and loss thorough spray nozzles. The loss through the spray nozzles are the greatest as they need a certain high pressure upstream to flow a given flow by converting the upstream pressure to kinetic energy/velocity, so although your pump may be rated for 4 m3/hr at 35 m, it may actually be operating at 50 m due to loss through the nozzles at 1.8 m3/hr flow. So it is pumping 1.8 m3/hr since the downstream pump can only be pumping what is input into the deaerator by the first pump
Likewise your second pump rated at 9 m3/hr at 40 m might be operating at a much higher pressure drop versus flow in the downstream piping system. In this case it may also be operating at say 50 to 60 m discharge pressure at 1.8 m3/hr. This is you have a piping system with a high pressure drop or the downstream vessel you are pumping into is a high operating pressure.
In any case both of your pumps are operating at the measured flowrate of 1.8 m3/hr at a high point (low flow) on your pump curve due to high losses in the piping system.
It could be that your downstream pump system is ok and does not have very high friction losses and it is just that your upstream pump flowrate is restricted due to the high pressure drop across the nozzles to get the spray. The downstream pump even if ok can only pump what flow it is supplied by the upstream pump.
You need to get data for your nozzles. Manufacturers publish flow versus upstream pressure for the nozzles. For a given flow desired they need to have an upstream pressure available. Then you do the pressure drop in the piping back to the pump and add to the nozzle head required to get the total system pressure drop in the piping to get your required pump output head. I suspect your deaerator nozzles are way undersized.
You need to get data for your nozzles. Manufacturers publish flow versus upstream pressure for the nozzles. For a given flow desired they need to have an upstream pressure available. Then you do the pressure drop in the piping back to the pump and add to the nozzle head required to get the total system pressure drop in the piping to get your required pump output head. I suspect your deaerator nozzles are way undersized.
LittleInch
Petroleum
What type of pumps are these?
PD type pumps will generally pump at a fixed flow, +/- 10%.
Centrifugal pumps generally provide a fixed differential head +/- 15% from your duty point.
T
The duty point flow is only one point on a curve. What flow you actually get is dependant on your downstream frictional and head losses.
PD type pumps will generally pump at a fixed flow, +/- 10%.
Centrifugal pumps generally provide a fixed differential head +/- 15% from your duty point.
T
The duty point flow is only one point on a curve. What flow you actually get is dependant on your downstream frictional and head losses.
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