Heat transfer for making coconut sugar

[Hammer_Time]

I'm currently helping out at a fair trade company in the Philippines who make coconut sugar. Part of the process requires the heating and stirring of the sugar at six different stations running in columns of two. They use an external heat source (to keep smoke away from the product) of burning saw dust (cheap and readily available to them) to heat the pans. The problem they have is while the first two stations receive ample heat the next two receive less and the last two less again. I have not visited the site (but will do) and have only had it explained to me. I was thinking about using blowers to transfer more of the heat to the other stations, but not sure how to go about it or even if its a viable options. Your thought on this would be much appreciated.

BTW this is my first ever post on any forum so sorry if its not quite right or missing some obvious details. Please let me know if you require more info.

[PinkertonD]

Hi Hammer, welcome and I envy you your Global location. My fondest work-life memories are of Asia. Love the people, the food, the mind-set of the average man in the street, the food, oh, did I mention the food??

OK, my first thought is how about having the pans in a circle and heat in the center. Maybe even have the pans on a turntable (lazy Susan) so the operator can swing the next set of pans closer to stir them. If the center heat is a little uneven, then turn the colder pans to the hotter section.

[Hammer_Time]

Thanks for the reply pinkerton.
Yeah I too I'm loving my time here, after this we do S.E.Asia (Thailand, Cambodia & all that lark). We are visiting as many fair-trade companies on our travels as possible.
As I mentioned in my thread I had only had the problem explained to me now due to a lack of understanding or a bad explanation I totally got the wrong end of the stick.
The problem they are having is keeping the sawdust burning, apparently the furnace/fire is forever going out?? I visit the site today and will have a much better understanding of the problem.

[RWOLFEJR]

It'd be a lot easier to burn the sawdust if they could pelletize it first.

[PinkertonD]

Hi Hammer, yup, that sound about right for explanations. I mean no disrespect to the people, but thy have funny ways of interpreting problems and then explaining stuff.

Don't get me started on some mining equipment designed in Japan and being modified and built in Britain. Once I figured out the correct way to ask questions and interpret answers, we were good, but that took a week or two at the start.

Do some research on sawdust fired heating systems. Used to be quite common in Britain in some of the older factories etc, probably still a lot of info on them. I have seen them loaded once a week and burn (smoulder) 24/7 giving off quite good heat with very little waste up the stack.

Ahhhh, Thailand, arguably the best food in the world.

[Hammer_Time]

Thanks guys, I'll look into both of these ideas for sure.
I've been and seen the site now and They have 2 furnaces sitting side by side, each has a 30cm square opening with a door (the only source of air) it then opens out in to a 2m wide x 2.5 m length x 1m deep chamber , they run three cooking stations on each . The temp of the first station (one nearest the furnace door) has to be the highest, so they generally don’t fill the full length of the chamber with fuel just the first meter or so. Both furnaces also have hoppers that can be used to feed in sawdust and other small fuels. Just to reiterate the problem they are having is the amount of fuel they go through, the fire going out and they have to constantly be managing it i.e. adding fuel, cleaning and checking on it. So they just want it to be more efficient.
• The first thing I noticed was that the door was left fully open all the time, more air equals faster burning right? So I asked them to just leave a little gap to slow the amount of air the fire had.
• The second thing was that 90% of their fuel (sawdust, coconut tree bark, coconut shells & a small amount of what I would call more common fire wood) was wet! Ha Ha no wonder your fire's going out! Although it will slow down the burn time considerably.
• Another thing I thought about was that if they raised the fire off the ground slightly (by using a metal grate of some kind) it would allow air to flow under giving a much more even burn. But not sure if it will then the fire would burn too fast or if they have room to do this?
• The last thing was the small size of the chamber; if it was bigger surely they could fill it and leave it for longer without having to constantly be adding fuel right?
I've added some pics so hopefully you can see the problem more clearly.

http://s1054.photobucket.com/albums/s496/Hammer_Time69/

And thanks again for any help, as I say it’s for a fair trade company so all in a good cause and just so you know I'm not being paid for this, it’s voluntary. A part from the odd free lunch and coconut wine of course

[PinkertonD]

Hammer, we do not care if you are being paid or not, either in money or in kind. We like to spread the joy of Engineering, so it's OK to make a buck on free advice given here as long as you are aware it is free and the value of the advice may well be directly related to the price.

As to raising the fuel, that is exactly why I mentioned the sawdust heaters. They have a very simple approach to the design that has probably been around about as long as sawdust and the need for heating. Hit the books.

[Hammer_Time]

Thanks for the help on this. Think I've got a plan together making the furnace more efficient now. Mainly involving to the sawdust and coconut fibres into briquettes. And using a rocket stove design to save energy. Now on to the next problem of granulating the sugar I think I'll start a new thread for that