6 replies to this topic

[ashton46]

I am trying to resize a centrifugal pump.  I am given the base case amount of the desired product produced, and the new amount that I want to produce, so I have that ratio.  I am also given the pressure drop, efficiency, temp, and shaft power of the original pump.  I am trying to get the new pump specs,  what equations should I use to get that?  

[Bobby Strain]

Why not tell us these values?

 

Bobby

[ashton46]

shaft power = 0.43 kW, efficiency is 40%, pin=1.13 bar, pout=3 bar,   plant produces 16000 ton/year of acetone, we want it to produce 50000 ton/ yr, so the ratio is 50k/16k =3.13

[breizh]

ashton,

You need to perform an hydaulic calculation for your entire system . You don't expect using the same pipe , don't you ?

 

To support your work use the search engine in this forum , you will find a lot of material to support your work .

 

Breizh

[Padmakar Katre]

I am trying to resize a centrifugal pump.  I am given the base case amount of the desired product produced, and the new amount that I want to produce, so I have that ratio.  I am also given the pressure drop, efficiency, temp, and shaft power of the original pump.  I am trying to get the new pump specs,  what equations should I use to get that?  

 

Hi,

You have mentioned that you resizing the pump, does it mean you already have a pump which is being checked for post revamp conditions or new condition if it's being retrofitted. If it's an existing pump just get the vendor performance curves for the pump and check the new conditions if these fall within the operating window.

 

If this is totally new system, then as suggested by members you can draw a sketch of pump circuit along with all resistance elements alongwith elevations on both side i.e. suction and discharge and perform the calculations. This is quite simple if understood correctly. You can serach in ChE forums or google with keyward like pump circuit hydraulics and you will find plenty of free stuff to start with.

[abubakarce19]

Pump Characteristic curve ( provided by vendor ) will be used to evaluate new condition ( high flow ) for feasibility study. Circuit hydraulics also need to be evaluated in case of complete system.  

[Mahdi1980]

Ashton,

To redesign a new pump you should specify the below characteristics of the pump for vendor:

1- Normal flow rate as you said 50000 ton/y = 6.25 ton/h

2- Characteristics of fluid in particular density and viscosity at operating conditions

3- min/max temperature

4- Required discharge pressure

5- NPSHa

For the last item , you should calculate the Available Net positive suction head according Bernoulli's equation from the source to the suction eye of the pump.

This is a very important item to select a centrifugal pump

Finally, the Minimum Flow is so important and vendor requires it. This is about 15~20% normal flow rate.

By the way, please try to buy a pump with a nearly flat performance curve to avoid dramatic change in pressure.

 

Hope it is helpful