10 replies to this topic

[Fiscopet]

Please i need on sizing a closed drain pump. Fluid is hydrocarbon

[Chemitofreak]

Hi,

 

Let us discuss with the sizing of the drain drum first followed by sizing of the drain pump

 

The drain drum is sized to hold the largest dead volume in the equipment of a plant i.e. volume below Low-Low Liquid Level.

 

This volume is the working volume of the drain drum.

 

The drain drum pump is sized to empty the drain drum in 20-30 mins.

 

This is a rough sizing of the system.

 

Mind you, I do not know your system, I don't know the volume in your system, I don't know how much capacity of your pump will be based on the aforementioned criteria. The philosophy needs to be discussed with your lead or the Client.

 

Please given more information about your system so that members in this forum can give you better inputs.

Edited by Chemitofreak, 23 April 2019 - 02:21 AM.

[breizh]

hi ,

So little info , how can we help you ?

A least provide a sketch with information about the flow to transfer . Is it a continuous process or batch ? what is the material ( flash point) ?

Most of the time I've seen vertical pump or immersed pump .

Waiting for your support .

Help us we will help you .

 

Breizh

[Fiscopet]

Breizh:

 

Drain Drum

drain drum size is 800mm diameter x 2850mm

 

Drain pump

-vertical immersed pump

 - outlet pipe size is 2"

 - fluid pumped is liquid

- density of liquid 734kg/m3

- mass flow rate of liquid  3500 kg/hr

-  viscosity 1.4cp

-   temperature 65oC

-  specific gravity of liquid 0.734 

-  vapour pressure 0.97barg

- design pressure 47 barg

-  design temp -29/ 71c

 - discharge line...approximately 9meters

 

I hope this info helps

[Fiscopet]

Chemitofreak:

 

Drain Drum

drain drum size is 800mm diameter x 2850mm

 

Drain pump

-vertical immersed pump

 - outlet pipe size is 2"

 - fluid pumped is liquid

- density of liquid 734kg/m3

- mass flow rate of liquid  3500 kg/hr

-  viscosity 1.4cp

-   temperature 65oC

-  specific gravity of liquid 0.734 

-  vapour pressure 0.97barg

- design pressure 47 barg

-  design temp -29/ 71c

 - discharge line...approximately 9meters

 

I hope this info helps

[Fiscopet]

Breizh:

 

Drain Drum

drain drum size is 800mm diameter x 2850mm

 

Drain pump

-vertical immersed pump

 - outlet pipe size is 2"

 - fluid pumped is liquid

- density of liquid 734kg/m3

- mass flow rate of liquid  3500 kg/hr

-  viscosity 1.4cp

-   temperature 65oC

-  specific gravity of liquid 0.734 

-  vapour pressure 0.97barg

- design pressure 47 barg

-  design temp -29/ 71c

 - discharge line...approximately 9meters

 

I hope this info helps

[breizh]

Hi ,

Thanks to clarify your needs or doubts .

You need to prepare a sketch with relevant information (altimetry ,etc  )  and specification sheet (flow rate , construction material for the pump) to submit to vendors .

You also need to define  how to operate the pump ( batch mode between levels High and Low) ?  if yes the capacity of the pump should be different (higher) from the 3500kg/h

NPSH could be an issue considering the VP of the liquid

Safety : flash point of your material , need for blanketing ? motor classification ...

 

Breizh

Edited by breizh, 23 April 2019 - 05:49 AM.

[Chemitofreak]

You have given details that are useful for pump hydraulics, these details are not at all helpful in finalizing the basis for pump flowrate. How have you finalised the outlet piping as 2" before finalizing the flowrate basis of the pump  

 

Anyway, I am doing a rough calculation for you based on some wild assumptions :

 

Based on the dimensions of the drain drum provided by you, the volume of the drum is approx. 1.6 m3. Considering the working volume (i.e. volume between the LLL and HLL) as 80% (you need to check based on your actual calculations) of the total volume, the working volume is 1.28 m3. Now assume the emptying time of this volume as 20 mins (need to get it confirmed by the Client/Principal Engineer or based on the handling capacity of the downstream system). Therefore the pump flowrate is 3.84 m3/hr (1.28 m3 in 20 mins).

 

Free Tip:

I assume that the drain drum is below the grade level, so you need a vertical pump, also check the feasibility of having a boot in the drain drum, this will lead to less dead volume in the drain drum i.e. the pump will be able to pump out maximum liquid from the drain drum. Based on my experience the boot can have a dimension of 0.8 m x 0.8 m.

[Art Montemayor]

Fiscopet:

 

Attached find some engineering forms and Data Sheets that may help you to specifically define your equipment and its specifications to vendors and for your project.  This information is intended to complement the excellent advice and comments you have received from Breizh and Chemitofreak.  Use it wisely and often.  The Data Sheets have taken a long time to construct and some may not be fully finished.  Some is Work in Progress and others are subject to upgrading and improvement as Excel has been modified and improved through the years.  I started these data sheets in Lotus 1-2-3 many years ago - well before our student members were born.  I try to upgrade them as I have time.

 

 

 Arts Process Spec Sheets Rev1.xlsx   666.77KB   108 downloads

 Pump Calculation Sheet.xlsx   51.05KB   105 downloads

[Fiscopet]

Fiscopet:

 

Attached find some engineering forms and Data Sheets that may help you to specifically define your equipment and its specifications to vendors and for your project.  This information is intended to complement the excellent advice and comments you have received from Breizh and Chemitofreak.  Use it wisely and often.  The Data Sheets have taken a long time to construct and some may not be fully finished.  Some is Work in Progress and others are subject to upgrading and improvement as Excel has been modified and improved through the years.  I started these data sheets in Lotus 1-2-3 many years ago - well before our student members were born.  I try to upgrade them as I have time.

 

 

Arts Process Spec Sheets Rev1.xlsx

Pump Calculation Sheet.xlsx

Thanks for this 

[Kashif Rao]

If there is discharge of HC liquid ( Crude with Sp. gravity 0.84)  PSV  ( conventional type)) into the closed drum. then what should be the basis for the volume consideration of closed vessel?

For how long should I consider the popping up of PSV?

should I consider malfunctioning of PSV ( popping up  below set pressure) scenario for the closed drain vessel?