13 replies to this topic

[Alzack]

Hi,

I'm trying to understand the concept to design a plate and frame heat exchanger (PHE) in a palm oil refinery.

I have the following datas:

Inlet temperature of bleach palm oil (BPO) : 100oC
Outlet temperature of BPO : 170oC

Inlet temperature of RBDPO : 194oC
Outlet temperature of RBDPO : 123.5oC

Mass flow rate of BPO: 35,000 kg/h
Mass flow rate of RBDPO : 33,500 kg/h

Specific heat © for BPO : 2.468 kJ/kgK
Specific heat © for RBDPO: 2.559 kJ/kgK

Now, the way i understand is I need to calculate the heat load (Q) in the PHE using Q=mc(theta) and I've calculated that
and get 1,679.95 kW.

The next step is to use Q = UAT ====> (T refers to T lmtd)

I already have the Q and I can calculate T (lmtd).

I need the U value (overall heat transfer coefficient) in order to get A (area).

When I get A, I can determine how much plate I need for my PHE (assume I know the area of a single plate).

Now, I cannot proceed because with the above equation to get A because I don't have U.

U depends on A and A also depends on U.

Any ideas what I should do?


I thought of using the formula :

1/u = 1/hu + x/k + 1/hi + Rf (Rf = fouling factor) to get the U value but the problem is I can't find value of

hu (heat transfer coefficient of BPO) and hi (heat transfer coefficient of RBDPO)


Any body can response and provide me some idea to solve this, I really appreciate it very much...



Thanks and best regardz

[breizh]

Hi ,
Let you go to Cheresources.com ( button left hand side) , you will get access to a paper on preliminary design for plates heat exchanger .
Hope this helps you
Breizh

[ankur2061]

Alzack,

I don't know why anyone would like to calculate the PHE area. PHE's are still specilaized items and there are very specific vendors such as Alfa-Laval, GEA who supply PHE's and have specialized design procedures for PHE's. If the idea is to procure a PHE then you only need to fill a process data sheet in which you provide the flow rates (hot/cold fluid), physical properties (density, viscosity of hot/cold fluid), overall heat duty, allowable pressure drops (cold/hot side).

If you actually want to size a PHE then there are some specialized texts which deal with PHE's. Some guidance is also given in GPSA engineering databook.

Hope this helps.

Regards,
Ankur.

[Mahesh@A&M]

Calculate Reynolds number based on number of substreams. Based on Reynolds number, use appropriate equation to calculate individual heat transfer coefficient and then overall heat transfer coefficient.

Use equivalent diameter(Deq) for Reynolds number calculation. Deq is 4 times the cross sectional area of the channel divided by the wetted perimeter of the channel.

Thank You
Mahesh

[Alzack]

I've read that before posting here. But I don't get what I want.

[Alzack]

Ankur,

Yep, I agree with you that the vendors have that specialized procedure, however I hope it is not wrong for us to know and comprehend the way of calculating and going about the sizing of PHE.

However, I really appreciate you giving me some tips on the handbook. I'll try and search for it now.

Cheers mate...

[Alzack]

Hi Mahesh,

Is this method that you suggested appropriate for plate heat exchanger? I'm sorry, I'm a little bit confuse...

[breizh]

Let you try this reference .

http://books.google....ulation&f=false

Breizh

[breizh]

Alzack,
As Ankur suggested you should ask vendor (alfa laval, Danfoss ,...) to support your query .

Danfoss is providing a calculator tool (DANFOSS CALCULATION HEAT EXCHANGER Tool) you can dowload from internet .

Hope this helps .

Breizh

[Zauberberg]

Danfoss is providing a calculator tool (DANFOSS CALCULATION HEAT EXCHANGER Tool) you can dowload from internet.

Hello Breizh

That was an interesting link. Does the Danfoss' software have any references/track record regarding the accuracy of results obtained by using this particular package?

Thanks,

[breizh]

Hello Zauberberg,
Sorry I cannot answer your question .
Breizh

[Propacket]

Hi,

I'm trying to understand the concept to design a plate and frame heat exchanger (PHE) in a palm oil refinery.

I have the following datas:

Inlet temperature of bleach palm oil (BPO) : 100oC
Outlet temperature of BPO : 170oC

Inlet temperature of RBDPO : 194oC
Outlet temperature of RBDPO : 123.5oC

Mass flow rate of BPO: 35,000 kg/h
Mass flow rate of RBDPO : 33,500 kg/h

Specific heat © for BPO : 2.468 kJ/kgK
Specific heat © for RBDPO: 2.559 kJ/kgK

Now, the way i understand is I need to calculate the heat load (Q) in the PHE using Q=mc(theta) and I've calculated that
and get 1,679.95 kW.

The next step is to use Q = UAT ====> (T refers to T lmtd)

I already have the Q and I can calculate T (lmtd).

I need the U value (overall heat transfer coefficient) in order to get A (area).

When I get A, I can determine how much plate I need for my PHE (assume I know the area of a single plate).

Now, I cannot proceed because with the above equation to get A because I don't have U.

U depends on A and A also depends on U.

Any ideas what I should do?


I thought of using the formula :

1/u = 1/hu + x/k + 1/hi + Rf (Rf = fouling factor) to get the U value but the problem is I can't find value of

hu (heat transfer coefficient of BPO) and hi (heat transfer coefficient of RBDPO)


Any body can response and provide me some idea to solve this, I really appreciate it very much...



Thanks and best regardz

Alzack,

HTRI is the best software for Plate & Frame Exchanger Design.I have used it and results are pretty close to those of vendor data sheets. HTRI manual is also available that provides complete descripition of the design procedure.

[breizh]

Hi Alzack ,

An other resource from APV .
http://www.apv.com/p..._08_2008_US.pdf

Hope this helps .
Breizh

[jcazenave]

if you are looking for a commercial solution

HTRI and AspenTech (Aspen Plate Exchanger) are the 2 main software providers for this type of application. You can contact them to have a quote.

Kind Regards