Paint shop heat transfer

[nh3simman]

I was asked today about heat recovery in a paint shop. They have a conveyor with 27000 kg of mild steel being processed in a 8 hour shift.

The steel is pre-treated in a tank of fluid at 50degC. It is then spray painted and heated to 60degC.

The 60degC steel is now air cooled to ambient. The question is, can this waste heat be recovered and injected into the pre-treatment tank.

My first though is to use a coil and circulate the pre-treatment fluid directly.

If I use a heat pump, I have the problem with a very high suction!

What are the alternatives here?

[NoNickName]

A drycooler in the room where the steel is cooled will warm the fluid, typically -15° than the air temperature.
This fluid at 45°C can be further heated to 50°C.
Perfect match: the fluid will cool while the steel is warmed, and then the fluid will be warmed while the steel is cooled.

[US Iceman]

Glycol run-around loop
Thermosiphon
Heat pump with suitable refrigerant for operating temperatures#1 & #2 only offer the possibility of recovering low grade heat, while #3 might make the process self-sufficient with no external heat source.

[nh3simman]

Thanks for the feedback. I like the idea of the runaround because of low capital cost.

The heat pump system does have the advantage of being able to achieve the design temperature. My only concern here is the potential for high suction but if the airflow is high enough and the room is maintained at about 10degC, this should never be a problem.

http://tinypic.com/view.php?pic=33tlbb7

http://tinypic.com/view.php?pic=33tlbb7

[nh3simman]

Here are some possible heat pump solutions.

As a quick subjective call, which do you think is best.

http://tinypic.com/view.php?pic=4hkvew7
http://tinypic.com/view.php?pic=42uvsr9
http://tinypic.com/view.php?pic=3yd61pz

[A_Ahed]

Dont 4get something
if u remove the heat from the chamber very quickly it may affect ur paint quality

[Peter_1]

We serviced for many years a HP (3 x 25 HP) at New Holland here in my backyard (now Fiat/Comau) where the heat was used to preheat the paint.
I should go for the last option with the watercooled condensor.
What's in the pre-treatment tank? Water or solvent?

[nh3simman]

may affect paint quality

Thanks, I was not aware of that.


What's in the pre-treatment tank? Water or solvent?

At this stage, I don't know what the pre-treatment fluid is, only that it is at 50degC. Water or solvent should be no problem for a shell and tube condenser.

[taz24]

I should go for the last option with the watercooled condensor


I would go with number three aswell.

taz