Recent content by ellatas

The Milwaukie Sentinel measured diacetyl within a roasting facility in Wisconsin last year and found levels above recommended guidelines. Currently there are no limits on the levels of diacetyl exposure in the US, but NIOSH has a draft standard that is likely to be implemented soon. When it...

Sounds like a great idea Musicphan! See you there! Cheers!

JohnD18 – It may be more beneficial for you to get a Green Bean Cleaner to remove your foreign materials. This will remove most rocks, twigs, string and other materials by feeding the coffee through a set of screens that separate “overs” and “unders” as well as an aspirator to remove dust...

Due to the higher airflows on a fluid bed roaster that are required to agitate the coffee, it cannot match the results from a drum roaster. It can come close, but the higher airflows strip more volatiles from the coffee. Its physics...heat and mass transfer. That said, both kinds can still...

An undersized afterburner can impair the performance two ways. One is the residence time and the other is the temperature. For larger roasters in most areas, the afterburner needs to be sized for 1200 degF with a half a second residence time. All this is dependent on the airflow from the...

The concept of different chambers in a continuous roaster has to do with different environments in each chamber. Since you need to maintain constant conditions of each chamber for extended periods of time (such as weeks), the way to change the heat applied to the coffee and create a particular...

Green coffee bulk density is typically between 38 and 42 lbs per cubic ft. Therefore, if you wanted a conservative estimation on the required volume for one 70 kg bag of green coffee, it could be calculated as follows: Mass = 70 kg = 155 lbs Volume = 155 / 38 = 4.08 cubic ft or 30.5 US gallons

Experience on the new roaster will be the best method to match profiles as there are many factors at play. Among the factors: the larger roaster will have more material to heat up and consequently take longer to reach 'steady state'; the roasters will have different insulation and will lose heat...

It depends on how you roast. When comparing gas vs electric, just like a stove top, gas has the potential for more "control-ability" in that it can turn on and off quicker than an electric element. There are faster reacting electric elements, but they can be brittle and less robust. That said...

This is good advice for roasters with batch sizes less than ~30kg. On larger roasters, however, it is best to keep the coffee in the rotating drum and utilize the water quench to ensure the coffee is not burning before it is released out of the roaster. The batch will be ruined, but releasing a...

mike Have you tried calling Probat? They're likely to be able to supply a replacement part along with instructions on how to replace it.

Axel, regarding drum speeds, the RPM should be less than (30/pi).(g/r)^1/2. Too much rotation will cause coffee to ride on the drum surface throughout the rotation and consequently not be in the hot air stream. Also, most drums have counter acting flights with outer flights (mounted on the drum...

Double wall (or insulated) drums do take longer to warm up. However, once they are at temperature they provide a stable environment for consistent roasting. As discussed above, the primary heat transfer medium is the air which can be manipulated (in temperature and airflow) relatively quickly...

Axel, regarding airflow, a good place to start is knowing the pick-up velocity of chaff. This across the cross sectional area of your drum will give you a good indication of the minimum airflow. For the maximum flow, a good indicator would be to ensure you are less than the pick-up velocity of...

The smaller the batch size, the easier it is to cool. Typically, however, it is best to have an even bed depth in the cooling tray with no open areas for the air to by-pass the coffee. The objective for the level bed depth is to ensure the resistance the air is subjected on its way to the blower...