Third, once the maximum airflow is determined, it is possible to determine heater power. Three considerations exit. The first consideration is to ensure that a reasonable pre-heat time can be achieved. Typically preheat times of approximately ½ hour are consistent with use case and customer acceptance. The second consideration is to ensure that there is enough heater power to generate drum inlet temperatures during roasting that provide enough head-room to get to dark roasts. Dark roasts are typically 460° F. so an inlet temperature of 590° F. is desired. Making the inlet temperature more than this is counterproductive as it can lead to bean surface ignition. During lighter roasts, it is possible to set inlet temperature lower than 590° F., but typically it is not set lower than 550° F. The third consideration for heater power is to ensure that total system power is still within the realm of electrical power that is generally available in retail coffee shop settings. This range is typically 6 KW (240V/24A) to 10 KW (240V/40A). So in one implementation, the heater power can be 4 KW.

Fourth, once airflow is known and reasonable heater power established, it is possible to select (or design) an inlet nozzle that provides desired agitation to the agitator blades to be spaced away from the inner surface of the roasting drum. The minimum gap of the blade from the roasting drum inner surface should be sufficient to clear the largest green coffee bean that may be present in a batch, depending on what types of coffee are to be roasted. Making the gap much bigger than this does not provide any advantage, and so the gap size is primarily selected (determined) by the target bean size. It is advantageous to not make the gap so big as to result in a very high agitation airflow from the nozzle to compensate for the large gap size. Restricting the dimensions of the nozzle adversely increases the backpressure that the main recirculating blower should overcome, which is not desirable as the increased backpressure increases the size of the blower and motor that drives it. Hence, a minimal but effective agitator spacing is desired. Making the gap smaller than the ideal will have the undesirable impact of crushing beans and at some point scraping against the sidewall of the drum, resulting in honing of the drum's surface to a precision diameter, which can increase cost of both the drum and the agitator.

For a very large roaster, a very high rate of airflow will be desired from the blower so the nozzle geometry may be larger and the target air speed higher than for a smaller roaster. For very large roasters, it may be desirable to have a slightly larger agitator spacing to ensure that the fabrication of the drum and agitator can be held to tolerances that promote ease of manufacturing and reduce cost.

As best illustrated in FIG. 3, air exits the roasting chamber 53 through an air outlet conduit 72 and passes to velocity decelerator 20 and then to cyclone separator 22. The cyclone separator 22 can also be referred to as a “chaff separator” 22, which may have additional or modified components beyond those described herein or shown in FIGS. 1-6.

FIG. 5 is an isometric drawing of the residual chaff and water collection vessel 33. Vessel 33 includes a upper and central chaff inlet 74 (also referred to herein as a “port” or a “chaff port”) for receiving residual chaff from the cyclone separator 22. Vessel 33 also has a water inlet 76 (also referred to herein as a “port” or a “water port”) for receiving residual water from the heat sink 26. The vessel 33 can be removably coupled to the bean roaster to allow for the collection of residual chaff and residual chaff during the roasting operation. Once the roasting operation is complete, the vessel 33 can be removed from the bean roasting (i.e., no longer coupled to the bean roaster) to allow for the residual chaff and the residual water to be expelled from the vessel 33. Thus, the chaff port 74 and the water port 76 are used to both receive and expel residual chaff and residual water, respectively. As shown in FIGS. 5 and 6, the chaff port 74 has a non-zero height and disposed above the planar portion of the lid of the vessel 33; the water port 76 is shaped as a spout that is disposed on a portion of the side wall of the vessel 33. Although shown with these particular sizes and shapes, it should be understood that a chaff port and water port can have different sizes, shapes and/or locations to allow for the residual chaff and the residual water to be expelled from the vessel 33 separately. For example, it may be desirable for the chaff port to have a greater height on the side proximate to the water port so that the residual water can be expelled from the water chamber without the residual chaff being expelled from the chaff chamber, as described further below.

FIG. 6 is a cross-sectional view of the residual chaff and water collection vessel 33 taken along line 6-6 in FIG. 5. As shown, the chaff chamber 24 and water chamber 32 are separated by an inner wall 78 (also referred to herein as a “wall” or a “first wall”). The vessel 33 also includes an outer wall (also referred to herein as a “wall” or a “second wall”). The water chamber 32 is defined as the chamber between the inner wall 78 and the outer water. In other words, the water chamber 32 is disposed between the inner wall 78 and the outer wall. The inner wall 78 (as well as the water chamber 32 and the outer wall) is disposed circumferentially about the chaff chamber 24. In other words, the inner wall 78 (as well as the water chamber 32 and the outer wall) surrounds the chaff chamber 24 along the vertical sides and the bottom side of vessel 33. Said yet another way, the inner wall 78 is disposed between the chaff chamber 24 and the water chamber 32.

A coupling 80 (FIGS. 1, 3) fluidically couples the cyclone or chaff separator 22 of the air handling system 10 to the chaff chamber 24, when the vessel 33 is coupled to the bean roaster (also referred to herein as a “first position”). For example, the chaff chamber 24 is fluidically coupled to the air handling system 10, when the vessel 33 is coupled to the bean roaster (in the first position). A fluid conduit 82 (FIG. 1) fluidically couples the heat sink 26 of the air exit subsystem 19 to the water chamber 32, when the vessel 33 is coupled to the bean roaster (in the first position). For example, the water chamber 32 is fluidically coupled to the air exit subsystem 19, when the vessel 33 is coupled to the bean roaster (in the first position).

The vessel 33 can also be removed from the bean roaster (also referred to herein as a “second position”). The vessel 33 can be removed from the bean roaster, for example, after the roasting process is completed and the residual water and residual chaff are to be expelled from the vessel 33 and discarded (e.g., in a water receptacle such as a sink for the residual water, and a trash receptacle for the residual chaff). The water inlet