METHOD TO ROAST COFFEE BEANS

Abstract

The invention concerns a method to roast coffee beans in a roasting system, said system comprising: a roasting apparatus (1), and a smoke treating unit (2) configured to treat the smoke produced by the roasting apparatus, said smoke treating unit comprising at least an electrostatic precipitator (222), said electrostatic precipitator comprising at least one cell, said cell comprising ionization wires, collecting electrodes and repelling electrodes and said ionization wires being supplied with an electrical power in order to apply a high voltage V to the ionization wires, wherein, during each roasting operation implemented in the roasting apparatus, the method comprises the steps of: monitoring the voltage V at the ionization wires and/or the electrodes along the time of the roasting operation, if the monitored voltage becomes inferior to a pre-determined voltage threshold V0 during a period of time of the roasting operation, and if said period of time, where the monitored voltage V is inferior to said lower voltage threshold V0 is superior to a pre-determined time threshold t, then displaying a cleaning alarm.

Claims

1. 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, 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 V at the ionization wires and/or at the electrodes along the time of the roasting operation, if the monitored voltage becomes inferior to a pre-determined voltage threshold V.sub.0 during a period of time t of the roasting operation, and if said period of time t is superior to a pre-determined time threshold t.sub.0, then displaying a cleaning alarm.

2. Method according to claim 1, wherein the pre-determined voltage threshold V.sub.0 is inferior to 100 V.

3. Method according to claim 1, wherein the length of the pre-determined time threshold t.sub.0 depends on the level of roasting implemented during the roasting operation and/or on the type of beans roasted during the roasting operation.

4. Method according to claim 1, wherein the length of the pre-determined time threshold t.sub.0 depends on the number of roasting operations implemented since the last cleaning operation of the electrostatic precipitator.

5. Method according to claim 1, wherein the length of the pre-determined time threshold t.sub.0 varies along the roasting operation.

6. Method according to claim 1, wherein the pre-determined time threshold t.sub.0 is of about few seconds.

7. Method according to claim 1, 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.

8. Method according to claim 1, 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 in each cell.

9. Method according to claim 1, wherein, if, for the two cells, the monitored voltage V at the ionization wires is inferior to the lower voltage threshold V0 during the same period of time of the roasting operation and said period of time is superior to the pre-determined time threshold t.sub.0, then an alarm for technical maintenance is displayed.

10. 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, said cell comprising ionization wires, collecting electrodes and repelling electrodes, 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.

11-13. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0126] Specific embodiments of the invention are now described further, by way of example, with reference to the following drawings in which:

[0127] FIG. 1 is a view of a system according to the present invention illustrating the path of the smoke through the system,

[0128] FIG. 2 illustrates one of the cell of the electrostatic precipitator part of the smoke treating unit of FIG. 1,

[0129] FIG. 3 shows a block diagram of a control system of the system according to FIGS. 1 and 2.

[0130] FIGS. 4A and 4B describe the voltage at the ionization wires monitored along the time of roasting operations.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0131] System for Roasting

[0132] 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.

[0133] Roasting Apparatus

[0134] The roasting apparatus 1 is operable to receive and roast coffee beans inside a roasting chamber 12.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] Preferably, the roasting apparatus comprises a user interface 13 enabling: [0140] 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 [0141] preferably about the output of information about the smoke treating unit 2 in particular about the cleaning of the electrostatic precipitator 222.

[0142] 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.

[0143] 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.

[0144] The rest of the smoke is evacuated through the smoke outlet 11 at the top of the roasting apparatus.

[0145] Smoke Treating Unit

[0146] The smoke treating unit 2 is operable to receive and treat the smoke S1 emitted at the smoke outlet 11 of the roasting apparatus.

[0147] 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.

[0148] 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.

[0149] 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: [0150] several ionization wires 2221, and then [0151] 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.

[0152] 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.

[0153] 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). 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.

[0154] 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.

[0155] In addition, in the particularly illustrated embodiment, the smoke filtering sub-unit 22 can comprise: [0156] 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. [0157] an active carbon filter 221 adapted to remove VOCs from the smoke.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] Control System of the System of the Roasting Apparatus and the Smoke Treating Unit

[0162] 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.

[0163] 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: [0164] 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. [0165] if the roasting apparatus 1 and the smoke treating unit 2 form two different apparatuses, each of them with its own control unit, then these control units can be configured to communicate to implement the method.

[0166] It may be possible to establish communication between the system of these two apparatuses with a mobile device too, in particular to display information.

[0167] FIG. 3 illustrates the control system of the smoke filtering unit 2 of FIG. 1.

[0168] 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 wire.

[0169] 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, where 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.

[0170] The control unit 30 may also display information to the user interface 13 about: [0171] cleaning instructions, [0172] reset of the alarm status.

[0173] 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.

[0174] 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.

[0175] 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 1, a slave integrated circuit to control the user interface 13 in communication with a master integrated circuit to control the roasting apparatus 1.

[0176] 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.

[0177] 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.

[0178] The instructions stored on the memory unit 31 can be idealised as comprising a program to determine a breakdown alert and a cleaning or maintenance requirement.

[0179] 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.

[0180] During a roasting operation, the control system 3 is operable: [0181] to monitor the voltage V at the ionization wires 2221 along the time of the roasting operation, [0182] if the monitored voltage becomes inferior to a pre-determined voltage threshold V.sub.0 during a period of time of the roasting operation, and [0183] to display a cleaning alarm, if said period of time t is superior to a pre-determined time threshold t.sub.0.

[0184] FIGS. 4A, 4B illustrates the evolution the monitored voltages of the two cells of one electrostatic precipitator during a part of a roasting operation. Curve A illustrates the evolution the monitored voltage of the first cell and Curve B illustrates the evolution the monitored voltage of the second cell. The voltage applied to the cells is normally 8 kV. The pre-determined threshold V.sub.0 is 100 V. The pre-determined time threshold t.sub.0 is equal to 5 seconds.

[0185] In FIG. 4A, it is observed that during the illustrated part of the roasting operation, the voltage monitored in the first cell becomes inferior to 100 V during a period of time t.sub.1 that is greater than t.sub.0, accordingly a cleaning alarm is displayed at this moment of the roasting operation or at the end of the roasting operation. During that period t.sub.1 a breakdown occurred and smoke was not filtered by the first cell during that time.

[0186] Similarly, the voltage monitored in the second cell becomes inferior to 100 V during another period of time t.sub.2 that is greater than t.sub.0, which confirms that the cleaning alarm is displayed at this moment of the roasting operation or at the end of the roasting operation.

[0187] In FIG. 4B, the voltage monitored in the first cell becomes inferior to 100 V during a period of time t.sub.1 that is greater than t.sub.0, accordingly a cleaning alarm can be displayed at this moment. In addition, the voltages monitored in both cells become inferior to 100 V during the periods of time t.sub.1 and t.sub.2, both greater than t.sub.0, and that overlap during a period of time that is superior to t.sub.0. During the overlapped periods of time, none of the cells is able to filter the smoke, which can lead to harmful problems. It is not recommended to implement new roasting operations and it is preferable to check the operating status of the cells. Accordingly, an alarm for maintenance is displayed at this moment of the roasting operation or at the end of the roasting operation.

[0188] 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.

[0189] 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.

[0190] 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

[0191] roasting apparatus 1 [0192] smoke outlet 11 [0193] roasting chamber 12 [0194] top outlet 121 [0195] user interface 13 [0196] smoke treating unit 2 [0197] smoke collecting device 21 [0198] smoke filtering sub-unit 22 [0199] active carbon filter 221 [0200] electrostatic precipitator 222 [0201] cell 222a, 222b [0202] ionisation wire 2221 [0203] collecting electrode 2222 [0204] repelling electrode 2223 [0205] PM filter 223 [0206] smoke driver 23 [0207] outlet 25 [0208] control system 3 [0209] control unit 30 [0210] memory unit 31 [0211] cell electric current supply 32 [0212] power supply 33 [0213] voltage sensor 34