Heat exchanger sizing

Hello Nikos,

Can you clarify this first:

Is it 36300Kg/Hr i.e. 36 Tons/Hr--. And now discharging to open sky through a Chimney? Can you send a photo of this Chimney discharging? Any Draft fan boosting?

Or is it 36.3 Kg/Hr?

Depending on either-attention of CR4 members may vary

mm

Hello! Thanking you about your time!

It is 36 tons/h... macive mass...

Please find herewith a copy of previous discussions, in order to be fully informed about (hope that this would help):

COPY 1

Hello!

Well this will be an actual design, which I have already finished the three dimencional design. The objective is to cool the hot air gases temperature down to 150 dergess, in order to be able to dedust the air stream through a large self cleaning filter unit. The pollution of the gases is relatevly small, below 200mg per cubic meter of air.

The cooling fresh air that will be warm after the cooling of the gases, will be used for room heating during winter time.

The idea for preheating the furnace is an option too.

The problem is that I do not have experience for heat exchangers.

I have serched a lot during the last couple weeks and I have managed to understant the maths of the heat transfer. I have made a two way aproach of the solution, one described in the books and one analyticaly of my own... giving similar results. I am preparing for a third, but in engineering the experience is of prime importance.

We are interested for the "know how" co-operation with others that will support us with their experience.

This is a pilot project and we have included emengency safe arrangements in order to maintain the gases temperature below 200 degrees.

But other projects may be folow after that, and they would be much more demanding and precise with the use of many and complex heat exchangers, including more technologies that we are not familiar of.

If you can help us and prove that you are capable of such designs, this would be a open invitation for co-operation.

Best regards

COPY 2

Hello again,

Well I tried to do what you suggested…

With my approach (model) I have the following results:

TOTAL MASS FLOW OF GASES = 36.282 kg/h

TOTAL FRESH AIR QUANTITY = 200.000 m³/h

1. Heat exchangers 8 pieces, diamond arrangement 10x20 tubes = 200 tubes (your proposal). Tubes are in vertical position. Gases inlet is on top. Fresh air inlet & outlet side of tubes (mixed flow).

Each heat exchanger:

Gases inlet = 450 °C - 0,4252 kg/m³ (x = 0,2 Kg/Kg) - 10.666 m³/h - 4.535 kg/h - 1,62 m/s

Gases outlet = 150 °C - 0,7979 kg/m³ (x = 0,2 Kg/Kg) - 5.684 m³/h- 4.535 kg/h - 0,86 m/s

Fresh air inlet = 30 °C - 1,1135 kg/m³ - 25.000 m³/h - 27.838 kg/h - 1,89 m/s.

Fresh air outlet = 79 °C

Tubes = 200 pieces – outer diameter 114mm (no fins) – inner 108mm – 3,8 meters each. Total length = 760 m.

For all the 8 exchangers = 6.080 m!!!

2. Heat exchangers 3 pieces, diamond arrangement 10x20 tubes = 200 tubes (my approach). Tubes are in vertical position. Gases inlet is on top. Fresh air inlet & outlet side of tubes (mixed flow).

Each heat exchanger:

Gases inlet = 450 °C - 0,4252 kg/m³ (x = 0,2 Kg/Kg) - 28.443 m³/h - 12.094 kg/h - 4,31 m/s

Gases outlet = 147 °C - 0,7319 kg/m³ (x = 0,2 Kg/Kg) - 16.524 m³/h - 12.094 kg/h - 2,51 m/s

Fresh air inlet = 30 °C - 1,1135 kg/m³ - 66.667 m³/h - 74.233 kg/h – 3,20 m/s.

Fresh air outlet = 79 °C

Tubes = 200 pieces – outer diameter 114mm (no fins) – inner 108mm – 6 meters each. Total length =1.200 m.

For all the 3 exchangers = 3.600 m…

The final difference is great… Seams that obviously I have done a mistake, because for the same result I have a way far different area…

What is your opinion?

Thanking you in advance

Regards

Hi,

Have you any software available (as HTRI for ex.), for the calculations?

I think with the data you have, HTRI will help you to find the best exchanger.

Unfortunately we dont have such a software...

Please see comment 3 (reply to comments 1) in order to be fully infromed.

I would like to thank you for your time and interest.

Best regerds