BTRV roasting machines, unlike BTRs, have 2 roasting drums.
The advantages are:
- Reduction of roasting times by making short cycles and more frequent discharges (about 5-6 minutes from 12 to 15 minutes).
- Reducing coffee weight decrease by optimizing heat exchangers
- Complete automation of the process, realized by the insertion of electronic sensors capable of piloting the interventions of both mechanical (loading / unloading) both thermal (heat transfer / subtraction)
- Energy saving (around 30%) compared to conventional machines
- With this kind of roasting process you can respect all 3 roasting steps (dehydration, heating and pyrolysis) precisely because it is carried out in 2 stages so that the characteristic roasting events proceed in succession.
In the first drum the amount and mode of heat delivery are such that only the dehydration and heating of the grains are produced.
In the second drum the actual roasting is developed, for which the thermal requirements are entirely special. Separation in two stages allows greater control over the whole process and hence an improvement in production in all respects.
RECYCLING SYSTEM AND SMOKE ABATEMENT
The roasting process of the coffee inside the drum is effected by conveying into it, through a recirculating fan, a flow of hot air generated in the combustion chamber; exiting the drum this air flow still hot (and with it the organic substances released by the coffee during the roasting) is largely conveyed back to the combustion chamber to return to the appropriate temperature and back to the drum; so only a small amount of hot air is evacuated into the atmosphere.
Heat administration during roasting is a very important factor; small / medium sized roasting machines are recommended / possible to install bi-step burners or progressive bi-step, while for large and automated medium machines it is opportune / necessary to install adjustable modulating burners throughout the thermal curve; they have the potential to carry out the two main functions:
- Heat the air to the temperature necessary for roasting.
- Permit the abatement of the organic substances released by the process.
To sum up a fan generates a recirculation of air that warms up in the combustion chamber, transfers the heat to the drum and gives it to the product, from here it flows into a cyclone to deposit the heavy substances and returns to the combustion chamber for recover the necessary thermal energy to transfer to the drum again.
The combustion chamber has a specific design that ensures a level of abatement of organic substances in line with current standards. The main advantages of this system are:
- Only the excess air is conveyed to the chimney in the atmosphere, which has already undergone the process of killing organic matter.
- The presence of only one burner for the two functions.
c- The integrated recirculation allows energy savings of 20-25% compared to conventional roasting machines.
NB: The process is almost always managed and controlled by an automatic system described below.
AUTOMATIC SYSTEM FOR ROASTING CONTROL (OPTIONAL)
BTR automatic roasting machines can be managed by a control system, which allows you to set and match certain parameters to the various types of roasted coffee (blend or mono source); the parameters mainly relate to the time and temperature values with which you can construct specific roasting profiles (otherwise the program or roasting curve).
The other parameters (from the load of green coffee to the drainage of the destoner and beyond) allow repeatability and conformity of roasting process; of course the values can be edited whenever you want.
The diagnostic system detects and warns any anomalies. The control system software, as mentioned, can be installed on a touch screen panel or on a personal computer. The touch screen panel is less direct than the PC, but it’s still a great tool, cheaper and less bulky, being installed on the control panel. Control software also includes the ability to manually manage some individual functions or utilities (for example, draining the hopper of green coffee, drum, cooler, etc.), while for reasons of warranty and safety are excluded the burner controls and heat flow control valves. The PC compared to the touch screen panel guarantees a wider management of the roasting process both for memory capacity and graphic representation. In addition, the control system is predisposed for connection to an Ethernet network (to be able to access the internet) through which it will be possible to use the remote telemarketing service. The control system is also equipped with VNC Server for Remote Control of the HMI device both on local (intranet) and external (Internet).