The final post for the Australian project.
Wednesday, November 3rd, 2010
We ran a couple more batches of coffee through before I left and again it performed exactly how we wanted it to. The tests that we ran demonstrated that this roaster will improve the roast quality even more than I originally thought. Before we started the roaster we got our new potentiometers and returned the old ones. The new ones are more sensitive and you can adjust them by extremely small increments on both the burner and blower control. In a fluid-bed roasting system the inlet air temperature directly affects the bean temperature. In our system this is more pronounced because with the control on the inlet-air temperature you can change the bean temperature in slight increments. If for example you want to change how long a roast will take or it you feel you want to bring the beans up to temperature faster in the last few minutes of the roast you can do either by making a simple adjustment on the control panel. The blower control allows for increased control but is also necessary with the control we have on the burner. As the inlet-air temperature changes so does the density of the air and its ability to push the beans. In other words, if you change the inlet-air temperature you have to be able to adjust your inlet-air velocity to compensate for the increasing and decreasing air density. The control on the blower is also nice because it allows you to change the dynamics of the fluidized bed. Independent of the inlet-air temperature, the control on the blower allows you to change the height and motion of the beans so you can make the bed as smooth or as chaotic as you want. As your beans lose weight and gain volume during the roasting process you can keep the bed of beans uniform. This also allows the person roasting to increase or decrease the batch size, within certain parameters. The stainless steel also proved to be a great benefit just as we planned. All roasters are going to get hot, no insulation stops heat, it only slows the transfer of heat. Even without an insulation shell the roaster only got really hot at the end of a 20 minute roast. When my client finishes installing their insulation the heat transfer will be incredibly small and it is my guess that all of the insulated parts will be cool enough to touch throughout the entire roast. This will be the last entry on the blog for this project. As we start new projects we will be back with new entries as the projects progress. We will also be updating the blog as we develop new roasters and designs. We are glad to be home and we are now taking orders on new roasters again. We offer 5 kg (10lb), 17 kg (37.5 lb) and a 34 kg (75 lb) roasters. For more information check out our web site and then send us an e-mail or give us a call.
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