Changing the Hot oil

[BZLAM21]

Dear All
Could anybody please help me, what is the impact in therm of capex and opex in the exchanger(shell and tube) if we change te hot oil with another oil (the first oil can reach max T=340C ° and the second max T=300C °).
SHELL SIDE INLET: HYDROCARBON
inlet T= 249 c°
outlet T= 255 c°
Specific Heat kcal/kg.c° = 0.690
masse =209000 kg/h

Tube side : Hot oil
inlet T=290 c°
outlet T=?
Specific Heat kcal/kg.c°=0.630
masse=?



Is there a way to estimate it?
Degradation of oil can cause what kind of problems?

Thanks

Regards,

 

[LittleInch]

You're in the wrong forum really - try the heat transfer one.

But this is quite an odd HX with only 5 C difference?

But it's a simple calc - mass x specific heat x delta T is energy so this only comes from the Oil.

Outlet oil temp can't be less than inlet temp plus 10 so say 260min or maybe 265. Then work out the mass flow. Simples.

Will be about 15 to 20% of the oil flow becasue you have a higher heat loss/

Now the issue if whether the HX has enough surface area for this quite low temperature difference - different issue.

Degradation of oil causes blockages of filters and less heat transfer.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pierreick]

Hi,
The change will increase the risk of degradation of hot oil, risk of fouling ,foaming risk, loss of heat transfer coefficient , need to replace more frequently the oil in the full system ( change over time to replace the entire volume , need chemicals to clean the system ,etc..)
You may need to install filters on the side of the hot oil unit to remove the dirt from degradation and consider to N2 blanketing the storage of hot oil.
Not easy to dispose the hot oil ( cost associated ).
In simple words think twice .
Pierre
Note : what is the aim for this change ?

 

[pierreick]

Hi ,
To add to my previous reply a document to support your work .
Pierre

 

[Compositepro]

In an oil to oil exchanger there is very little probability of overheating and degradation of oil because the upper temperature is strictly limited. The problems with oil degradation and coking are mainly in electric or fired heaters where anything that reduces heat transfer at any point on the surface will cause large increases in local temperature. And coking is auto-catalytic.

 

[pierreick]

Hi ,
I don't agree with Compositepro , based on experience on distillation columns , maximum temperature about 195 C , Hot oil HTF 66 .
Consider the link attached you will get information about degradation , design ,...

https://durathermfluids.com/understanding-fluid-degradation/

other links

https://www.therminol.com/sites/therminol/files/documents/TF50_Therminol_HTF_Optimizing.pdf

https://www.process-heating.com/art...t-transfer-fluid-oxidation-and-its-prevention

Good luck ,
Pierre

 

[BZLAM21]

tank you pierreick Compositepro