Cleaning "Tar" buildup from drum vent

[skydragondave]

Hello all,
I'm the mechanic for a coffee-roasting company operating out of a community centre in Hamilton, Canada. I have a Has Garanti HG5 that we have been running for about five years now. We are rapidly ramping up production and I have been finding an excessive buildup of "tar" or organic oil buildup in the drum exhaust piping. I have not removed the drum cover to examine the inside of the roaster, but opening the sight flap just under the green bean hopper shows a lot of buildup, and I am scraping the drum exhaust fan and housing every 6 months. It's very labour intensive and rough on the exposed surfaces, and I am wondering if there is an easier way to remove this material, especially inside the exhaust pipe running from front to back along the top of the machine, which I will have to unbolt from the roaster for cleaning.

Thanks for any suggestions, D

[chokkidog]

Some ideas for you to try...........

1. Send Mark of Coffee Roasters Australia an email with your enquiry.
Mark is the Australian distributor of HG. Contact Us Gold Coast | Coffee Machines Australia | Coffee Roasters Australia

2. Locate an industrial chimney sweep or industrial food grade flue cleaner in your area.

3. Get it nice and clean, then clean it more often.

4. Make up some cleaning tools or purchase some from a chimney sweep supply company,
there must be truckloads in Canada!!

5. Removing the horizontal flue along the top of the drum is easy............... if it's a tight fit
getting it back on can be a ##^%#^, I know, I've done it. The easier way is to unbolt the exhaust fan and motor
and clean from that end.

6. Oil? Tar? Sounds like creosote. How far past 2nd crack do you roast? 8-D

[skydragondave]

Hi Chokkidog,
Thanks for the reply. Mark has been absolutely fantastic in answering my questions in the past, and I don't want to exploit his good nature, but may have to if I can't resolve this problem some other way. My opportunities to do business with him are limited as I am literally on the other side of the planet. I take my hat off to him for caring enough to help someone who is unlikely to generate a sale. If I ever move to Australia and get into the business, guess who will be the first guy I call.
I scrape the exhaust fan and housing on a six-month schedule, and we have agreed to tighten the interval to two months based on increased production and what I am seeing on the machine. Imagine taking a bar of baker's semi-sweet chocolate and freezing it to -18C, then attempting to scrape a channel in it with a flat-head screwdriver. That is the appearance, consistency and tenacity of the material coating the exhaust piping and it is generally about 3-4mm thick when I service the machine. I have very little knowledge of coffee production beyond the basic process and am in no position to advise our roastmaster on adjusting his technique for optimum machine service life. Our focus is on product quality and our beans are flying off the shelves, so I have no issue with the tar being there; I just want to find the best way to get it out of there. Perhaps a heatgun or an alcohol-based solvent wash of some kind?
Thanks again for your thoughts, D

[Vinitasse]

For what it's worth, I have been consistently roasting 50-65 batches each week and I make a point of removing and thoroughly cleaning the horizontal flue weekly. It only takes 20-30 minutes to remove, clean and then replace. Perhaps if you cleaned yours much more often you wouldn't have to scrape away so much baked on gunk next time around. And... I do have to agree with chokkidog... if the residue is that dark and hard it does sound like creosote and I can only assume that you sell a lot of Full City or French roasts back in Canada. I happen to be Canadian myself but am very grateful that here in Australia there is an appreciation for milder, non-carbonized roasts that actually taste like coffee... it certainly makes the cleaning routine easier ;-)

[chokkidog]

Heat may help, I wouldn't put solvent near my roaster but that would be up to you.
It may be an option as a once off but I would definitely get good advice on that first.

Is there someone near you who does dry ice blast cleaning, used in food machinery (such as industrial food ovens),
automotive and all sorts of cleaning?


I'm with Vinitasse; with your situation - get it clean, then keep it clean with a regular short cycle program,
weekly or by batch number, you could also try cleaning the horizontal flue when it is warm from the last roast
rather than leave it a day or more to 'set'.

[skydragondave]

Hi,
Our dark-roast beans seem to be the most popular. Perhaps this is what's causing the thick buildup. We roast about fifteen or so different varieties from various places, here's our lineup:
Coffee | Homegrown Hamilton
I have found that this buildup is just as difficult to remove whether it's a thin film or a thick coating. The crystalline buildup in our flue and chimney piping is very simple and easy to brush off, and we do this on a quarterly basis. We will be tightening-up on this as well.

I have been consistently roasting 50-65 batches each week and I make a point of removing and thoroughly cleaning the horizontal flue weekly.

How are you removing buildup?

Thanks again, D

[Vinitasse]

Roasting much lighter than what you have to deal with there really isn't much to clean and a wire flue brush does the trick for the most part, and a metal rod gets at the more difficult to reach bits

[chokkidog]

Roasting much lighter than what you have to deal with there really isn't much to clean and a
wire flue brush does the trick for the most part, and a metal rod gets at the more difficult to reach bits

Yep, same as vinitasse, there's not a lot to do................
My cleaning kit consists of a vacuum cleaner for the cooling tray assembly and around the inside top of the cyclone
and with a 'mini vac tool kit' to get at hard to get to spots around the burner/gas train,
a piece of wire to clear any blocked holes in the cooling tray, a hand held wire brush and a wire flue brush.
A couple of rags to keep the outside spic 'n span, with some warm water to clean the cooling tray sides & mixer arms.

If your flue get cold, <250*F, the creosote will condense on the flue pipe, at temps of <150*F, the creosote will be thick and sticky.
This will trap carbon from the smoke of dark roasted beans which, in turn, dries and then bakes like a glaze.

Your problem arises from your dark roasts, if this is your desired roast level, fine, no problem, what you need then, is a cleaning strategy to
work with this extreme degree of roast. Insulating your flue against the cold will lessen the condensation. Frequent cleaning
would seem to be necessary. As a last resort, using a flue assembly where the first metre or two
can be disposed of in the recycling every couple of months and replaced with new sections could be an option, especially if it's a simple, straight flue.
Then you only have to deal with the actual roaster parts that need the regular cleaning.

One place where I did some contract roasting engaged a chimney sweep to do regular maintenance on the three story flue pipes.
He had to do the work and his insurance carried the risk! Too easy!! 8-D

[skydragondave]

One place where I did some contract roasting engaged a chimney sweep to do regular maintenance on the three story flue pipes.
He had to do the work and his insurance carried the risk! Too easy!! 8-D

That's exactly what I do too.

So if I made an insulating sleeve tailored for the horizontal flue with that silver fabric on the outside and ceramic fiber on the inside, might that reduce buildup? I can live with scraping out the fan housing but getting that horizontal flue cleaned out is going to kill me.

[chokkidog]

I'm not sure about insulating the horizontal flue on the roaster. It may muck up your exhaust flue temps and change your roast profile.
You would have to ask someone with more experience than me.
The only other thing I can think of for cleaning that part, is for you to make up a mechanical brush using an electric drill and a round wire flue brush
on a steel shaft. a bit like a paint stirrer fitting for a drill. It might mean removing the flue if you can't make one long enough
to get all the way in from where the exhaust fan is mounted at the back end of it.
Something like these products:

Drill Carbon Steel Wire Brush Set 3Pc | Screwfix.com

Cheers

[skydragondave]

Hi Chokkidog,
I went and took a look at the roaster again last night with these suggestions in mind. You are right, I cannot insulate the horizontal flue. The hi-temp probe is installed just at the back end of the flue here and is designed to turn off the burner if the heat rises beyond 250* (C? F? I can't remember) so if I need to be above that temp to prevent creosote condensation, I can't run the machine. Second, there is a butterfly valve on the back end of the flue as well just before it goes into the fan housing (where the lo-temp probe is located) which would get in the way of a brush or reamer if I wanted to go all the way through. This really sucks because if there was none, I could simply remove the exhaust fan and poke this device through the flue whilst I was cleaning the fan housing. Alas, it has to be unbolted and removed to clean it out.
On the upside, the flue from the fan housing to the chaff collector is just cheap galvanized which can be easily replaced when it gets bad, though from the chaff collector to the chimney liner is stainless and will have to be cleaned.
Maybe ethyl alcohol followed by a food-grade stainless cleaner would speed things along? And maybe a brass pipe cleaner of appropriate diameter run through to the valve with a drill.

Man.....

[chokkidog]

I would still explore the dry ice blasting, if you can. There's a clip on utube where it's being used to clean roaster parts,
it looks the goods. Other than that you could try to track down some tech support from a roaster manufacturer, installer/maintenance
people or someone with a lot of dark history, oops, dark roasting history that is;-)
Have you had a professional chimney sweep look at it?

Sorry skydragon, I'm all out of useful ideas, so good luck with the house keeping!! 8-D
Please post when you resolve your problem, I'd be interested to hear how it ends up.

Cheers!