Recently we purchased our new roaster (which you can read about on the site here) https://silverskincoffee.ie/2019/04/10/new-equipment/
In a bold move, we decided that our existing 15kg roaster would be upgraded to match the roasting style of the new machine.
This meant taking out the existing drum (thermodynamic) and replacing it with a new one (Vortex).
Here is a note on both technologies.
Thermodynamic Drum: The most advanced drum available in today’s industry. Built from two layers of mild steel with a middle layer of pure copper, it has extremely high thermal absorption and heat conduction characteristics. In contrast to standard drums in which roasting is performed by direct, limited contact between the beans and the drum. The Thermodynamic Drum exhibits a unique scheme of sophisticated heat conduction applied to a wider contact surface between beans and drum. Heat is transferred via the copper layer creating a 1.4 mm gap between the heat and the beans, removing any risk of burn marks. This drum excels in producing an evenly roasted batch of superb beans, allowing a higher range of temperature operation, and writes its own new language in thermal dialog – just imagine, reflected heat conduction.
Vortex Drum: Drum air-inlet screens configured at vortex geometry to allows very efficient high velocity air. This drum is 4 mm thick, made of two separate layers of perforated mild steel.
The perforated drum utilizes infrared radiation for roasting. The radiation is produced by the flame which is positioned horizontally, parallel and underneath the drum inside the ceramic combustion chamber. This drum is indifferent to the type of rare plate as air flows through the drum walls and around. This drum also requires low airflow to prevent excessive conveying heat by the air.
The perforated drum produces a stronger taste and a higher rate of caramelization in sugars. This much desired outcome occurs without running the risk of producing roasts with burnt marks on the surface of the beans as may happen while caramelizing with solid drums. Using this drum may prove favorable for filter coffee roasters or those who seek to obtain intense tastes for their espresso roasts.
No easy feat especially when the bearing housing at the front of the roaster refused to let go! Eventually we separated the old drum and installed the new one (which is considerably bigger) this meant adjusting the combustion chamber slightly or simply put saw away some of the protective housing *scary stuff.
One of the main reason for the adjustment to the housing was for the new burner to be placed inside. The old burner was a Pre-mix single nozzle**
Pre-mix single nozzle burners are first level new-generation gas burners. Not only that, they can operate as multi-fuel burners. Such burners are equipped with a centrifugal blower able to calibrate air quantity. They also come equipped with a calibration valve that controls gas quantity. Controlling gas quantity ensures air and fuel mix in accurate amounts resulting in complete combustion that derives maximal caloric value.
Just like with anything else, there are many manufacturers of these burners. Design and quality naturally vary. In a good quality burner, a projecting/radiation nozzle or a heat-radiating metal screen will be installed to supplement the mixing chamber. Such efficient setup secures oxidation at the tip of the flame. This gets rid of toxins such as NOx and SOx generated by improper gas combustion. In its more basic form, this burner cannot be modulated using a single control knob. Modulation requires optimizing air quantity manually with almost every single change in desired gas quantity.
This was upgraded to a Fully modulated burner with greater control for sure ** see a note from the manufacturer about it’s high cost and over exuberance……if you’re gonna do it you’re gonna do it though right 🙂
Fully modulated burners
Just like in the single/mono stage, in pre-mix single nozzle, multi-stage, or fully modulated burners caloric value can be changed and adjusted during roasting. With this type of technology, where the burner is located in a closed combustion chamber with optimal heat distribution, there is no need for full-resolution control. Two or three stages will provide perfect control for all commercial roasting purposes. Some roasting masters will nevertheless consider this insufficient. That is also fine: the technology is already here to match. As long as you promise to use it and are willing to pay for it, it can certainly integrate into your made-to-measure roaster. However, sometimes, high functionality can also be a source of confusion. Some clients are better off without a wide control range. Trust me, I have been supporting clients online for way more than twenty years since the early days of the Internet.
Having said that, 100% control is vital when the flame hits the drum directly. In this case, it is absolutely necessary to be able to go down to very low caloric values. On the opposite end, when the drum compartment is open and un-insulated, one has to take into account the cold surrounding air that interferes with the roasting process.
So simple really we have upgraded our existing roaster to ensure all roasts, all styles match up no matter which machine we use. Its been a huge learning curve already but one we are thoroughly enjoying.
if you’re following our intstagram you’ll see the hours spent uninstalling and reinstalling the kit.
Hopefully its worth the effort for our customers.