Induction Heating Roasting Drum Temperature Control
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Solution Overview
Problem
Existing roasting machines face limitations in controlling temperature rise and air flow during the roasting process, leading to inconsistent quality and efficiency, particularly in horizontal drum roasting machines with direct and indirect heating methods.
Innovation Solution
A roasting machine equipped with an electromagnetic induction heating system, utilizing an outer steel cylinder and inner shaft to induce eddy currents for heat generation, allowing precise temperature control and reduced air flow, thereby overcoming these limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If direct heating with resistors is used around the drum, then heating power is sufficient, but the drum surface temperature becomes excessively high causing burn risks and energy loss
Solution Approach 1:
An intermediate air layer is introduced between the heating resistors and the drum surface. This air layer acts as a thermal mediator that transfers heat to the drum through convection and radiation while preventing direct contact heating, thus maintaining sufficient heating power while limiting the drum surface temperature to safe levels.
Solution Approach 2:
A controlled flow of air is introduced into the heating chamber using pneumatic means. This air flow circulates between the resistors and the drum, providing convective heat transfer that distributes thermal energy evenly while preventing localized overheating of the drum surface.
2Temperature
If indirect heating with air flow through the drum is used, then temperature control is improved, but oxidation of bean surface occurs
Solution Approach 1:
The heating chamber is filled with an inert or low-oxygen atmosphere (such as nitrogen or controlled air) instead of free air circulation through the drum. This creates an oxygen-depleted environment that prevents oxidation of the bean surface while still allowing thermal energy transfer to the drum and beans through radiation and controlled convection.
3Power
If gas heating with high air flow is used, then heating efficiency is high, but temperature rise becomes uncontrolled and oxidation occurs
Solution Approach 1:
Temperature sensors are positioned to monitor the thermal state of the drum and beans, and this information is fed back to the control system. The controller adjusts the gas burner output and air flow rates in real-time based on the measured temperatures, ensuring that heating efficiency is maintained while preventing uncontrolled temperature rise and oxidation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The induction heating system enables high specific power, efficient heat transfer, and precise temperature control, resulting in improved roasting quality and reduced energy consumption.
Implementation Method 1
at least one induction coil (15) externally and coaxially to the rotating drum, which substantially covers the entire surface, in order to induce an electromagnetic field in the cylinder
Implementation Method 2
The currents induced in the cylinder create through the Joule effect the generation of heat
Implementation Method 3
the currents induced in the cylinder create through the Joule effect the generation of heat which, by radiation and convection, will be transferred to the rotating drum
Implementation Method 4
the currents induced in the cylinder create through the Joule effect the generation of heat which, by radiation and convection, will be transferred to the rotating drum
Implementation Method 5
The currents induced in the cylinder create through the Joule effect the generation of heat
Data Source
Figure 1
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AI summary
Roasting machine (100) for seed material comprising a loading conduit (5) for introducing the material to be roasted into a horizontal drum (1), perforated substantially over the whole surface, supported by a rotating shaft (3) and defining a roasting chamber (61), and an unloading conduit (6) for recovering the treated material, said horizontal rotating drum (1) being internally provided with a series of paddles (7) for stirring the material, wherein, in operation, said rotating drum (1) is traversed by a flow of air between an air inlet conduit (16) and an outlet conduit (17) for discharging the volatile gases that develop during the roasting operation, wherein externally and coaxially to the rotating drum (1) a fixed outer cylinder (13) in steel is provided, which is in turn surrounded by insulation (14) outside of which is placed at least one coil (15) coaxial to the rotating drum (1), to induce an electromagnetic field in the cylinder (13) in such a way that the currents induced in the cylinder (13) create by the Joule effect the generation of heat which, by radiation and convection, is transferred to the rotating drum (1) and therefore an indirect heating of the same and of the roasting chamber (61).