METHOD TO ROAST COFFEE BEANS

Abstract

The invention concerns a method to roast coffee beans in a roasting system (10), said system comprising: a roasting apparatus (2), and a smoke treating unit (3) configured to treat the smoke produced by the roasting apparatus, said smoke treating unit comprising at least an electrostatic precipitator (222), wherein, during each roasting operation implemented in the roasting apparatus, the method comprises the steps of: monitoring the voltage at the ionization wires and/or to the voltage at the electrodes along the time of the roasting operation, comparing the monitored voltage to a pre-determined upper voltage threshold V1 and to one pre-determined lower voltage threshold V2, and if, during a period of time t of the roasting operation, the monitored voltage is inferior to said pre-determined upper voltage threshold V1 while being superior to said pre-determined lower voltage threshold V2, then displaying a cleaning status requirement.

Claims

1-15. (canceled)

16. A method to roast coffee beans in a roasting system, said system comprising: a roasting apparatus, and a smoke treating unit configured to treat the smoke produced by the roasting apparatus, said smoke treating unit comprising at least an electrostatic precipitator, said electrostatic precipitator comprising at least one cell, and said cell comprising ionization wires, collecting electrodes and repelling electrodes, and said cell being supplied with an electrical power in order to apply a high voltage to the ionization wires and at least a part of the electrodes, wherein, during each roasting operation implemented in the roasting apparatus, the method comprises the steps of: monitoring the voltage at the ionization wires and/or to the voltage at the electrodes along the time of the roasting operation, comparing the monitored voltage to a pre-determined upper voltage threshold V1 and to one pre-determined lower voltage threshold V2, and if, during a period of time t of the roasting operation, the monitored voltage is inferior to said pre-determined upper voltage threshold V1 while being superior to said pre-determined lower voltage threshold V2, then displaying a cleaning status requirement.

17. Method according to claim 16, wherein the ratio V1/V2 is superior to 10.

18. Method according to claim 16, wherein the cleaning status requirement is displayed if: the monitored voltage is inferior to said at least one pre-determined upper voltage threshold V1 while being superior to said pre-determined lower voltage threshold V2, and the period of time t is superior to a pre-determined time threshold t1.

19. Method according to claim 18, wherein the pre-determined time threshold t1 is less than 10 seconds.

20. Method according to claim 16, wherein the cleaning status requirement is displayed if the monitored voltage is less than at least one pre-determined upper voltage threshold V1 while being greater than said pre-determined lower voltage threshold during more than one period of time t of the roasting operation.

21. Method according to claim 16, wherein the step of monitoring the voltage and the step of comparing the monitored voltage are implemented during a part of the time of the roasting operation only.

22. Method according to claim 16, wherein the smoke treating unit comprises a high voltage process control board configured to control the electrostatic precipitator and wherein the monitored voltage is read from said process control board.

23. Method according to claim 16, wherein the electrostatic precipitator comprises at least two cells, said cells being positioned successively along the flow of the smoke emitted by the roaster, and wherein said method is applied at least on the first cell along the flow of the smoke.

24. Method according to claim 16, wherein the value of the pre-determined upper voltage threshold V1 varies according to the number of roasting operations implemented since the last cleaning operation of the electrostatic precipitator, preferably said value decreases with the increasing number of roasting operations.

25. Method according to claim 16, wherein the system comprises a meter configured to estimate the number of roasting operations still operable before the cleaning operation of the electrostatic precipitator is required, and the value of the pre-determined upper voltage threshold V1 varies according to said estimated number,

26. Method according to claim 24, wherein depending on the value of the pre-determined upper voltage threshold V1, a corresponding type of cleaning status requirement is able to be displayed.

27. Method according to claim 16, wherein the system comprises a sensor configured to measure particulate matters of the smoke treated by the electrostatic precipitator and the method comprises the steps of: measuring the concentration of particulate matters during a roasting operation, comparing the cleaning requirement status with said measured concentration.

28. A system for roasting coffee beans, said system comprising: a roasting apparatus, and a smoke treating unit configured to treat the smoke produced by the roasting apparatus, said smoke treating unit comprising at least an electrostatic precipitator, said electrostatic precipitator comprising at least one cell, and said cell comprising ionization wires, collecting electrodes and repelling electrodes, and said cell being supplied with an electrical power in order to apply a high voltage to the ionization wires and at least a part of the electrodes, and a control system operable to control the roasting process comprising: a roasting apparatus, and a smoke treating unit configured to treat the smoke produced by the roasting apparatus, said smoke treating unit comprising at least an electrostatic precipitator, said electrostatic precipitator comprising at least one cell, and said cell comprising ionization wires, collecting electrodes and repelling electrodes, and said cell being supplied with an electrical power in order to apply a high voltage to the ionization wires and at least a part of the electrodes, wherein, during each roasting operation implemented in the roasting apparatus, the method comprises the steps of: monitoring the voltage at the ionization wires and/or to the voltage at the electrodes along the time of the roasting operation, comparing the monitored voltage to a pre-determined upper voltage threshold V1 and to one pre-determined lower voltage threshold V2, and if, during a period of time t of the roasting operation, the monitored voltage is inferior to said pre-determined upper voltage threshold V1 while being superior to said pre-determined lower voltage threshold V2, then displaying a cleaning status requirement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0140] Specific embodiments of the invention are now described further, by way of example, with reference to the following drawings in which:

[0141] FIG. 1 is a view of a system according to the present invention illustrating the path of the smoke through the system,

[0142] FIG. 2 illustrates one of the cell of the electrostatic precipitator part of the smoke treating unit of FIG. 1,

[0143] FIG. 3 shows a block diagram of a control system of the system according to FIGS. 1 and 2,

[0144] FIGS. 4 and 5 illustrate the evolution of monitored voltage and emitted particulates during roasting operations at two different status of fouling of the collecting electrodes,

[0145] FIG. 6 is a magnified view of one roasting operation illustrated in FIG. 4.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0146] System for Roasting

[0147] FIG. 1 shows an illustrative view of a system of a roasting apparatus 1 and a smoke treating unit 2. Functionally, the roasting apparatus is operable to roast coffee beans and the smoke treating unit is operable to treat the smoke generated during roasting by the roasting apparatus.

[0148] Roasting Apparatus

[0149] The roasting apparatus 1 is operable to receive and roast coffee beans inside a roasting chamber 12.

[0150] Preferably, the roasting apparatus 1 comprises a roasting chamber 12 in which a flow of hot air is introduced to agitate and heat the beans. The hot air flow is usually produced by an air flow driver and a heater. These devices are positioned below the roasting chamber and introduce the flow of hot air through the bottom of the chamber. In the illustrated figure, the bottom of the chamber is configured to enable air to pass through, specifically it can be a perforated plate on which the beans can lie and through which air can flow upwardly.

[0151] The air flow driver is operable to generate a flow of air upwardly in direction of the bottom of the vessel. The generated flow is configured to heat the beans and to agitate and lift the beans. As a result, the beans are homogenously heated. Specifically, the air flow driver can be a fan powered by a motor. Air inlets can be provided inside the base of the housing in order to feed air inside the housing, the air flow driver blowing this air in direction of the chamber 12.

[0152] The heater is operable to heat the flow of air generated by the air flow driver. Preferably, the heater is an electrical resistance positioned between the fan and the perforated plate with the result that the flow of air is heated before it enters the chamber 12 to heat and to lift the beans.

[0153] The heater and/or the fan are operable to apply a roasting profile to the beans, this roasting profile being defined as a curve of temperature against time.

[0154] Preferably, the roasting apparatus comprises a user interface 13 enabling: [0155] the input of information about the roasting, in particular the quantity of beans introduced inside the roasting chamber and the desired level of roasting, and the output of information about the roasting operation (status, temperature, time) and [0156] preferably about the output of information about the smoke treating unit 2 in particular about the cleaning of the electrostatic precipitator 222.

[0157] The roasting of the beans generates a smoke that is driven to the top opening 121 of the roasting chamber due to the flow of air generated by the air flow driver and as illustrated by arrow S1 in FIG. 1.

[0158] Generally a chaff collector is in flow communication with the top opening 121 of the chamber to receive chaffs that have progressively separated from the beans during roasting and due to their light density are blown off to the chaff collector.

[0159] The rest of the smoke is evacuated through the smoke outlet 11 at the top of the roasting apparatus.

[0160] Smoke Treating Unit

[0161] The smoke treating unit 2 is operable to receive and treat the smoke S1 emitted at the smoke outlet 11 of the roasting apparatus.

[0162] First, the smoke treating unit 2 comprises a smoke collecting device 21 adapted to collect the smoke. This smoke collecting device 21 or collecting device forms an internal void space or duct guiding the smoke (dotted lines S1, S2, S3) from the outlet 11 of the roasting apparatus in direction of the filtering devices of the smoke filtering sub-unit 22.

[0163] The smoke filtering sub-unit 22 comprises an electrostatic precipitator 222 adapted for filtering small particulate matter such as PM.sub.1, PM.sub.2.5 and PM.sub.10. This electrostatic precipitator 222 comprises two identical cells 222a, 222b, positioned successively one after the other in the flow of smoke.

[0164] FIG. 2 illustrates the main components of cell 222a. The cell 222a is configured to be traversed by the smoke and comprises successively according to the direction of the flow of smoke: [0165] several ionization wires 2221, and then [0166] several collecting electrodes 2222 and repelling electrodes 2223, usually in the form of parallel plates, positioned in an alternate manner in at a distance of few millimetres. The plates are oriented to create channels for the flow of smoke.

[0167] A high voltage level (in the range of 8 kV in this case) is applied on the ionization wires 2221 to create a corona discharge that charges the particles of the smoke entering the cell.

[0168] An electrical field is created by the collecting and repelling electrodes by applying a difference of voltage between the collecting and repelling electrodes (for example applying 4 kV to the collecting electrodes and fitting the repelling electrodes to ground in this case).

[0169] When the charged particles flow in the channels defined by the alternate collecting and repelling electrodes, these charges particles are attracted onto the collecting electrodes 2222 by the electric field which is perpendicular to the flow direction.

[0170] The cleaning operation of the electrostatic precipitator 222, consists in removing the cells 222a, 222b of the electrostatic precipitator from the smoke filtering unit and washing them with water and optionally with a detergent for example in a dishwasher.

[0171] In addition, in the particularly illustrated embodiment, the smoke filtering sub-unit 22 can comprise: [0172] a device 223 adapted for filtering large particulate matter like PM.sub.10, for example a metallic mesh and an associated diffuser, generally a metallic grid positioned in front (that is upstream) of the mesh. [0173] an active carbon filter 221 adapted to remove VOCs from the smoke.

[0174] Preferably, the device for removing particulate matter are positioned upstream the active carbon filter. This upstream position guarantees that particulate matter do not foul the active carbon filter.

[0175] Physically, the electrostatic precipitator is positioned below the active carbon filter to avoid that particulates fall from the electrostatic precipitator on the active carbon filter when the electrostatic precipitator is switched off.

[0176] The smoke filtering sub-unit 22 comprises a smoke driver 23, generally a fan, for sucking the contaminated smoke from the inlet 211 of the collecting device through the smoke filtering sub-unit 22, where it is treated, to the outlet 25 of the smoke filtering sub-unit 22, where it is dispensed in ambient atmosphere safely.

[0177] Control System of the system of the roasting apparatus and the smoke treating unit

[0178] With reference to FIGS. 1, 2 and 3, the control system 3 will now be considered: the control system 3 is operable to control the smoke filtering unit 2 and in particular the electrostatic precipitator 222 of the smoke treating unit.

[0179] Depending on the level of integration of the roasting apparatus 1 and the smoke filtering unit 2, the control system can be shared between the control units of these two apparatuses: [0180] if the smoke treating unit 2 is part of the roasting apparatus 1, usually the control unit of the roasting apparatus is the master and the control unit of the filter is the slave. [0181] if the roasting apparatus 1 and the smoke treating unit 2 form two different apparatuses, each of them with its own independent control unit, then these control units can be configured to communicate to implement the method.

[0182] It may be possible to establish communication between the system of theses two apparatuses with a mobile device too, in particular to display information.

[0183] FIG. 3 illustrates the control system of the smoke filtering unit 2 of FIG. 1.

[0184] The control system 3 typically comprises at a second level of smoke filtering unit 2: a processing or control unit 30, a power supply 33, a memory unit 31, a voltage sensor 34 for the ionization electrode.

[0185] The control unit 30 is configured to output feedback to the user interface 13 of the roasting apparatus in particular to display a cleaning requirement status of the electrostatic precipitator. In an alternative configuration, the some treating unit 2 can comprise its own user interface to display this status, for example lighting buttons that can be lighted according to the status.

[0186] The control unit 30 may also display information to the user interface 13 about: [0187] cleaning instructions, like tutorials, historic data about cleaning operations, . . . [0188] reset of the alarm status.

[0189] The hardware of the user interface may comprise any suitable device(s), for example, the hardware comprises one or more of the following: buttons, such as a joystick button, knob or press button, joystick, LEDs, graphic or character LDCs, graphical screen with touch sensing and/or screen edge buttons. The user interface 20 can be formed as one unit or a plurality of discrete units.

[0190] A part of the user interface can also be on a mobile app when the apparatus is provided with a communication interface 32 as described below. In that case at least a part of input and output can be transmitted to the mobile device through the communication interface 32.

[0191] The control unit 30 generally comprises memory, input and output system components arranged as an integrated circuit, typically as a microprocessor or a microcontroller. The control unit 30 may comprise other suitable integrated circuits, such as: an ASIC, a programmable logic device such as a PAL, CPLD, FPGA, PSoC, a system on a chip (SoC), an analogue integrated circuit, such as a controller. For such devices, where appropriate, the aforementioned program code can be considered programmed logic or to additionally comprise programmed logic. The control unit 30 may also comprise one or more of the aforementioned integrated circuits. An example of the later is several integrated circuits arranged in communication with each other in a modular fashion e.g. a slave integrated circuit to control the smoke treating unit 2 in communication with a master integrated circuit to control the roasting apparatus 10.

[0192] The power supply 33 is operable to supply electrical energy to the said controlled components and the control unit 30. The power 33 may comprise various means, such as a battery or a unit to receive and condition a main electrical supply.

[0193] The control unit 30 generally comprises a memory unit 31 for storage of instructions as program code and optionally data. To this end the memory unit typically comprises: a non-volatile memory e.g. EPROM, EEPROM or Flash for the storage of program code and operating parameters as instructions, volatile memory (RAM) for temporary data storage. The memory unit may comprise separate and/or integrated (e.g. on a die of the semiconductor) memory. For programmable logic devices the instructions can be stored as programmed logic.

[0194] The instructions stored on the memory unit 31 can be idealised as comprising a program to determine the level of dirtiness of the smoke treating unit of the system and in particular the cleaning status requirement (no cleaning necessary, urgent cleaning at the end of the present roasting operation, . . . ).

[0195] The control unit 30 is configured to output the value of the voltage V at the ionization wires 2221 and measured by a sensor 34. In a preferred embodiment, the voltage can be directly read from the high voltage PCB of the electrostatic precipitator.

[0196] During a roasting operation, the control system 3 is operable: [0197] to monitor the voltage at the ionization wires and/or the voltage at the electrodes along the time of the roasting operation, [0198] to compare the monitored voltage to a pre-determined upper voltage threshold V.sub.1 and to one pre-determined lower voltage threshold V.sub.2, and [0199] if, during a period of time t of the roasting operation, the monitored voltage is inferior to said pre-determined upper voltage threshold V.sub.1 while being superior to said pre-determined lower voltage threshold V.sub.2, then to display a cleaning status requirement.

[0200] FIG. 4 illustrates the evolution of the emitted PMs and the monitored voltages during successive roasting operations (no 1 to 6).

[0201] Curve C illustrates the measure of PM.sub.2.5 emitted during the roasting operations and measured upstream the electrostatic precipitator (that is before treatment by this filtering device).

[0202] The voltage at the ionization wires 2221 of the upstream cell 222a, and the downstream cell 222b respectively, during these roasting operations is represented by curve A, and curve B respectively.

[0203] It is observed that during a roasting operation, the voltage V at the ionization wires varies and presents the general pattern of decreasing from an initial voltage V.sub.0 (about 7 kV), then reaching a lowest value of voltage V.sub.low (illustrated by black dots) and then increasing up from said lowest value to the initial voltage V.sub.0 at the end of the roasting operation. Starting from a recently cleaned electrostatic precipitator and implementing several roasting operations, it has been observed that the value of the lowest voltage V.sub.low becomes lower and lower at each roasting operation as illustrated by the dotted line. This lowest value is a measurable parameter providing information about the level of collection of particles on the collecting electrodes.

[0204] When a part of the monitored voltage, such as the lowest value V.sub.low, becomes inferior to the upper voltage threshold V.sub.1that was set and is represented at 4.5 kV in FIG. 4an alarm is displayed to draw the attention of the operator to the fact that a cleaning operation is required.

[0205] Through Curve B, it can be noticed that the monitored voltage of the other cell 222b does not decrease comparably. This is due to the fact that the upstream cell 222a traps about 90% of the PMs. As a result the downstream cell 222b is not fouled as rapidly.

[0206] The upper voltage threshold V.sub.1 can be pre-defined through endurance tests during which roasting operations emitting the highest levels of PMs (that is preferably beans roasted to dark level) are repeated and the voltage is monitored. As operations are reiterated and the lowest values of voltage decrease, the appearance of first breakdowns reveals the deposit of very high levels of PMs in the plates. Since these breakdowns are not desired (PMs being dispensed in the room or blocking downstream active carbon filter if present), the upper voltage threshold V.sub.1 is defined so that, even if the voltage reaches this threshold during a roasting operation, then no breakdowns happen during said operation.

[0207] FIG. 5 illustrates the evolution of the emitted PMs and the monitored voltages during successive roasting operations identified as no x to no x+5 where the operation no x+1 is the first operation during which the monitored voltage is inferior to the voltage threshold V.sub.1 set at 4.5 kV.

[0208] Like in FIG. 4, Curve C illustrates the measure of PM.sub.2.5 emitted during the roasting operations and measured upstream the electrostatic precipitator and the voltage at the ionization wires 2221 of the upstream cell 222a, and the downstream cell 222b respectively, during these roasting operations is represented by curve A, and curve B respectively.

[0209] The curve A illustrates the situation where, between the roasting operation no x and the two following operations no x+1 and no x+2, the monitored voltage of cell 222a becomes inferior to V.sub.1 during each roasting operation. During these both operations, no breakdown occurs and the filtering operation is still safe, but if further operations happen after the roasting operation no x+2, it is noticed that during all the following roasting operation no x+3 to no x+5, the monitored voltage dips extremely low to values inferior to V.sub.1 which means that breakdowns systematically happen during these operations. Accordingly, in a safe manner, the upper threshold V.sub.1 is set at a voltage superior to the first lowest voltage observed with breakdown (that is 3.2 kV during operation no x+3).

[0210] Through the analysis of curve B, it can be noticed that the second downstream cell still efficiently traps the PMs during the roasting operations no x+1 to no x+3 but that this second cell becomes rapidly fouled too and subject to breakdowns without capacity to filter the smoke. Accordingly, displaying an alarm urging the operator to clean the electrostatic precipitator immediately after the end of the roasting operation no x+1 and the detection of the problem in the first upstream cell is highly preferable.

[0211] FIG. 6 is a magnified view of the roasting operation no 6 extracted from FIG. 4. it makes apparent that, at time t.sub.1, the monitored voltage drops to a value almost equal to zero during a very short period. The value was inferior to 100 V and the period was inferior to 5 seconds. Such a low voltage corresponds to a false breakdown. It can be due to the short contact established by a particle between two electrodes and that almost immediately disappeared, the particle being carried away by the flow of smoke. This false breakdown does not provide information about the fouling of the cell of the electrostatic precipitator. Accordingly if the monitored voltage is inferior to the lower threshold V.sub.2, which itself is inferior to the upper threshold V.sub.1, no cleaning status requirement is displayed. The lower voltage threshold V.sub.2 can be set to about 100 V.

[0212] Experimentations of roasting operations with the system of the electrostatic precipitator and the roasting apparatus such as illustrated in FIGS. 4 and 5 enable the pre-determination of the value of the upper threshold V.sub.1.

[0213] In addition, since the lowest voltage of the curves A and B progressively decreases, it is possible to define several pre-determined upper voltage threshold V.sub.11, V.sub.12, . . . with V.sub.11>V.sub.12>V.sub.1, such as illustrated in dotted lines in FIG. 4, in order to progressively alert the operator with different cleaning status requirements becoming more and more alarming. For example, when the monitored voltage remains above the upper threshold V.sub.11, a message can be displayed that more than N.sub.1 roasting operations can be implemented before cleaning is required, N1 corresponding to 2/3 of the usual total number of operations possible with a cleaned cell. Then, when the monitored voltage is between the upper thresholds V.sub.12 and V.sub.11, a message can be displayed that between N1 and N2 roasting operations can be implemented before cleaning is required, N2 corresponding to 1/3 of the usual total number of operations possible with a cleaned cell.

[0214] Then, when the monitored voltage is between the upper thresholds V.sub.1 and V.sub.12, a message can be displayed that less than N2 roasting operations can be implemented before cleaning is required.

[0215] Finally, when the monitored voltage is inferior to the upper threshold V.sub.1, a message is displayed that cleaning must be operated before operating a new roasting.

[0216] Usually, the upper threshold V.sub.1 (or optionally pre-determined voltage threshold V.sub.11, V.sub.12, . . . ) is set in the setting menu of the roasting system based on these pre-determined experimentations. This threshold is stored in the memory 31 of the control unit 30. Based on this threshold, once the monitored becomes close to this threshold during one roasting operation, then an alarm for cleaning is displayed.

[0217] In general, when the upper threshold V.sub.1 is reached by the monitored voltage during a roasting operation, the alarm urges the operator to clean the electrostatic precipitator before any new roasting operation is implemented because breakdowns will systematically happen at the next roasting operations with the result that PMs filtering are not filtered.

[0218] This method is particularly useful when the operator forgets to clean the electrostatic precipitator although she/he has been already informed through the display of another alarm for cleaning for example an alarm based on the a number of hours of roasting operations. The new display for an urgent cleaning before next roasting operation urges her/him to act. This new display guarantees that, if the operator follows the recommendation of cleaning, no breakdowns of the electrostatic precipitator will happen during the next operations and the the public will remain in a safe environment around the roasting system.

[0219] Preferably, during a roasting operation, the control system 3 is operable to display the cleaning status requirement if: [0220] during a period of time t of the roasting operation, the monitored voltage is inferior to said at least one pre-determined upper voltage threshold V.sub.1 while being superior to said pre-determined lower voltage threshold V.sub.2, and [0221] this period of time t is superior to a pre-determined time threshold t.sub.1. Preferably, this pre-determined time threshold t.sub.1 is about 5 seconds.

[0222] In FIG. 5, it can be observed that during the roasting operation no x+1, the monitored voltage of cell 222a is inferior to the threshold value V.sub.1 during a period of time t that is superior to 1 minute (actually, the scale of time in FIG. 5 is such that one roasting operation lasts at least 15 minutes in FIG. 5). Such a low voltage during such a long period of time cannot be considered as an isolated low value of the voltage and consequently this measured voltage is retained to initiate the display of a cleaning alarm.

[0223] If this period of time t had been very short, for example less than 5 seconds, then this measured voltage would not have been retained to initiate the display of a cleaning alarm. The fact of taking into account the length of the period of time t provides a more accurate cleaning requirement status.

[0224] In an alternative or complementary method, the control system can be operable to: [0225] monitor the voltage at the ionization wires and/or to the voltage at the electrodes along the time of the roasting operation, [0226] calculate the moving average of the monitored voltage over the roasting operation, [0227] compare said calculate moving average with the pre-determined lower voltage threshold V.sub.1, and [0228] if, during a period of time t of the roasting operation, the moving average is inferior to said pre-determined upper voltage threshold V.sub.1, then to display a cleaning status requirement.

[0229] The calculation of the value of voltage with a moving average provides the advantage of smoothing fluctuations and excluding outliers over a number of measurement points, in particular the false breakdowns or the abnormal low values of voltage (inferior to V.sub.1) when they happen over a very short period of time.

[0230] Although the invention has been described with reference to the above illustrated embodiments, it will be appreciated that the invention as claimed is not limited in any way by these illustrated embodiments.

[0231] Variations and modifications may be made without departing from the scope of the invention as defined in the claims. Furthermore, where known equivalents exist to specific features, such equivalents are incorporated as if specifically referred in this specification.

[0232] As used in this specification, the words comprises, comprising, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean including, but not limited to.

LIST OF REFERENCES IN THE DRAWINGS

[0233] roasting apparatus 1 [0234] smoke outlet 11 [0235] roasting chamber 12 [0236] top outlet 121 [0237] user interface 13 [0238] smoke treating unit 2 [0239] smoke collecting device 21 [0240] smoke filtering sub-unit 22 [0241] active carbon filter 221 [0242] electrostatic precipitator 222 [0243] cell 222a, 222b [0244] ionisation electrode 2221 [0245] collecting plate 2222 [0246] repelling plate 2223 [0247] PM filter 223 [0248] smoke driver 23 [0249] outlet 25 [0250] control system 3 [0251] control unit 30 [0252] memory unit 31 [0253] cell electric current supply 32 [0254] power supply 33 [0255] ionization electrode voltage sensor 34