Design liquid velocity recommended by TEMA

[mechengineer]

Hi Experts in shell & tube heat exchanger thermal design,
Kindly advise the design velocity for fluid (like cruel oil) recommended from TEMA and which para. is in TEMA.
Thanks

 

[davidparker]

Hi Experts in shell & tube heat exchanger thermal design,
Kindly advise the design velocity for fluid (like cruel oil) recommended from TEMA and which para. is in TEMA.
Thanks

Typical design velocity for crude oil in shell & tube heat exchangers is around 1-2 m/s in the tubes and 0.3-1 m/s in the shell, but it depends on factors like fouling and pressure drop limits. Check TEMA Standards under the 'Mechanical Design' and 'Thermal Design' sections for specific recommendations. Someone with a copy handy might be able to point out the exact paragraph!

 

[pierreick]

Hi,
Consider reading this paper.
To mitigate the fouling, you could consider special devices, paper attached.
Pierre

 

[EdStainless]

It depends a lot on composition of the fluid and the tube materials.
In general the higher the alloy content the better the erosion (and erosion-corrosion) resistance.
My TEMAs are all on paper but if you need something I could scan a page.
Though they are a great reference to own.

 

[goutam_freelance]

I could not locate the tube-side velocity limit in TEMA. This may be because TEMA is a manufacturing standard rather than a design standard(even though many clauses in TEMA pertain to design, e.g., shell diameters, etc.).

However, Heat Exchange Institute (HEI) does provide limits for tube side velocities for power plant heat exchangers(for feed water quality water) as below (Ref Cl 3.4)

1. SS, Ni Alloy, Ti:-10 fps
2. Cu-Ni:-9 fps
3. Admiralty, Cu, Al-Brass:-8.5 fps
4. CS:-8 fps

I feel these limits can also be used for normal water in other industries. For other liquids, the specialized limits as applicable should apply.

 

[mechengineer]

Thanks for all inputs.
The real case as below. This thermal design is done by client (user).

 

[goutam_freelance]

I am not in this specialized field.

But this site may help:

Key Personnel

Process Improvement Engineering: Chemical engineering consultants specializing in continuous chemical plant and oil refinery troubleshooting, operation, and design.

www.lieberman-eng.com

Especially "PROCESS DESIGN FOR RELIABLE OPERATIONS".

Good Luck!

 

[LittleInch]

Thanks for all inputs.
The real case as below. This thermal design is done by client (user).

That table is going to need some explain as nothing seems to make sense.

E.g. case1 and 3 are similar mass flow yet 3 is half the velocity??

But velocities appear to be unreasonably high and don't seem to make a lot of sense but we only have 5% of the information.

Is this a case of someone just getting some numbers from a program or spreadsheet and not putting brain into gear?

 

[Christine74]

Just to provide the relevant background info selecting the appropriate tube-side velocity is a balancing act of the following considerations:

1) Pressure drop
2) Convective heat transfer
3) Fouling mitigation (higher velocities result in higher shear stress as the fluid interface with the ID of the tube, thereby inhibiting fouling)
4) Erosion potential

Basically you want the velocity high enough to provide adequate heat transfer and protect against fouling without having an excessively high pressure drop or tube erosion. This can often be accomplished by selecting the appropriate number of tube passes (1, 2, 4, 8 etc.).


-Christine

 

[EdStainless]

I could not locate the tube-side velocity limit in TEMA. This may be because TEMA is a manufacturing standard rather than a design standard(even though many clauses in TEMA pertain to design, e.g., shell diameters, etc.).

However, Heat Exchange Institute (HEI) does provide limits for tube side velocities for power plant heat exchangers(for feed water quality water) as below (Ref Cl 3.4)

1. SS, Ni Alloy, Ti:-10 fps
2. Cu-Ni:-9 fps
3. Admiralty, Cu, Al-Brass:-8.5 fps
4. CS:-8 fps

I feel these limits can also be used for normal water in other industries. For other liquids, the specialized limits as applicable should apply.

Those seem a bit off to me.
1. Ti is often run up to 12 fps, SS and Ni alloys the only real limit is pressure drop. I have seen >50fps in high alloy SS.
2. 8-9 fps is common in CuNi, 90/10 is more sensitive than 70/30
3. I could go 8fps in Al brass, but admiralty and Cu should be about 6fps unless you want 5 year life.

 

[mechengineer]

The table is from HTRI reports for evey cases.
Regardign the high velocity, if vibration is not an issue at the high speed, then the service/design life of the S31803 tube at the high speeds (erosion) may only be the concern point. Am I right?
Thanks

 

[georgeverghese]

Agreed, running at 11m/sec on tubeside with 22Cr std duplex would be acceptable only if crude oil has no erosion corrosion potential

 

[mechengineer]

Thanks, geogeverghese.

 

[EdStainless]

One things that needs attention with high velocities (other than vibration and erosion) is the inlet and outlet erosion issues.
And this HX will be very noisy.

 

[LittleInch]

The table is from HTRI reports for evey cases.
Regardign the high velocity, if vibration is not an issue at the high speed, then the service/design life of the S31803 tube at the high speeds (erosion) may only be the concern point. Am I right?
Thanks

It might be from HTRI, but it still didn't make sense. Mass flow rate bear no relationship to velocity