I'm finding all the sweet spots now for gas and air flow on the big 30kg batch roaster, trying to move my 5kg batch roaster to the six times bigger capacity 30kg is surprisingly working very well - but then roasting coffee is very much like baking a cake - you need precise measurements of ingredients and control the temperature exactly so they cook at the perfect time and the end result is the ideal colour you were aiming for. Roasting coffee is an art, there is no fixed rule for different origins - the same origin will do mostly the same thing - so Ethiopian Yirgacheffe always takes the same time to roast at the same amount of gas, Brazillian Santos takes a different amount of gas and air flow to roast in the same time, Indian Monsooned Malabar takes a very different amount of gas and air flow to roast in the same time. Each different origin will do the same repeatedly - but each requires it's own unique setting for gas and air to get the best from them....it's coffee roasting art.
Pouring 5kg of green coffee into the hopper of a 5kg batch roaster is relatively easy even for someone short of stature like me. 30kg, unless you want to be going up and down ladders with 10kg batches is not so easy. For big batch roasters like my 30kg a pneumatic loader is an optional extra - it has a ground level hopper attached to the hopper on top of the roaster with a long tube - you fill the ground level hopper and then turn the loader fan on with the control panel - and it literally blows the coffee beans into the hopper on top of the roaster!
Here you can see the loader ground level hopper, and it's tube that the green coffee blows through into the big hopper that sits on top of the roaster. The door that releases the green coffee into the roaster drum is controlled pneumatically by a button on the control panel, although the roast profiling software actually opens and closes it automatically when you start the profile off.
Once in the drum the coffee beans start to roast, on the 30kg batch roaster there are two windows to see the roasting coffee - the drum spins clockwise and the coffee beans are constantly churned and turned for even roasting.
When the roast is done and the coffee has reached the desired darkness of roast pressing a button on the control panel pneumatically opens the door to release the coffee too cool. The profiling software on the machine actually allows you to set this cooling process automatically - you can program the temperature you expect the coffee to be at the perfect roast colour and when the machine reaches it the drum opens, the cooling tray mixer starts and the cooling fans turn on to suck cold air over the bean to cool them. Very, very cool!
So far I have run ten batches through the new roaster, all my self installed ducting is sealed perfectly. When the gas engineer fitted the gas line we discussed ventilation, the roaster has a large gas burner that consumes oxygen. The noxious fumes from the burner are not a real concern because the roaster has a forced air flow - it has an exhaust fan that sucks air passed the burner then through the drum over the coffee and takes the chaff from the beans out and into the chaff collector before it then heads through the ducting outside. But like any gas burner it consumes Oxygen, so there has to be an open ventilation channel for fresh air to replace the oxygen. There is a Window opposite to the right of the roaster location and we decided it was large enough to provide sufficient fresh air. Only problem was it is ladder height up the wall to open, and it was secured shut with iron bars since we moved in twelve years ago.
Behold proof of @c0ff33a brain mk3 - after ten minutes up a ladder removing the iron bars screwed in across the window to keep it shut - I found it had a mechanism for opening where if you lifted the latch it would open - and you could lift it the other way to close the window. But being so high up I would need to have ladders in front of the window to climb up and open it....
Or I could drill a hole in the set square pictured which was one of the many random things abandoned in this warehouse when I took it over, and bolt it to the window latch. When I am using the roaster I can walk up to the window, lift the set square from ground level to open the window. And when I am finished roasting, lift and pull back to close it.
Other additions to the roaster space are a Carbon Dioxide fire extinguisher - these are the best option for electrical fires and also leave no residue. As a business we have a yearly inspection by a Fire Safety company that checks all our extinguishers (you need to have a set amount based on the surface area of your building, we have over twenty Fire Extinguishers over the two floors and each year they are checked, logged and if they are too old replaced) Also a Carbon Monoxide detector for the gas burner, I have one for the smaller 5kg roaster too - in the three and a half years I have been using it the Carbon Monoxide detector never went off - again because coffee roasters have a forced air flow all the toxic gasses from the burner are carried outside by it.
Now I have the windowsill sorted out it can store my 50 litre food grade tubs, they easily hold 20kg of green coffee but once roasted max about 18kg because the beans expand a little when roasted.
When the windows were replaced three years ago the windowsill was left open - just a gap with rubble in it. I cut down coffee roaster crate panels we had spare to make the sill ledge, screwed it to the brick and after painting used brown silicone to fill the gaps and some spare trim. Also here you see the new double socket I fitted next to the roaster for the vacuum cleaner which I need all the time, and a computer in the future to use Artisan profiling for the roasts, plus an extension to the Air Compressor.
And after, cables covered, edges sealed with silicone and flashing in place. It's a warehouse and doesn't have to look beautiful, but I'm cooking a food product here so it needs to be clean, tidy and acceptable.
All I need now is for the coffee shops and restaurants to be allowed to open! Coronavirus is causing hard times on all of us, support your local business where you can.
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I distribute coffee roasting machines and also espresso coffee machines and roast my own Speciality Coffee Range. being one of the premium coffee suppliers Yorkshire including a wide range of filter coffee sachets. Finally I have a dedicated website to my Artisan small batch roasted coffee featuring roast and post packs and super easy coffee subscriptions.
The Coffee Break Discord Voice Chat Show, in @thealliance Mondays 10pm UTC hosted by @c0ff33a and @enginewitty
