METHOD FOR DRYING A SMOKE FILTER UNIT

Abstract

The invention concerns a method for drying at least one cell of the electrostatic precipitator of a smoke treating unit in a system of a coffee beans roasting apparatus and a smoke treating unit, said method comprising the step of passing hot air through said cell, while said cell is positioned inside the electrostatic precipitator and while said cell is switched off.

Claims

1. A method to dry at least one wet removable cell of an electrostatic precipitation smoke filter of a smoke treating unit of a roasting system, said system comprising: a roasting apparatus, a smoke treating unit configured to treat the smoke produced by the roasting apparatus, said smoke treating unit comprising said electrostatic precipitation smoke filter, said electrostatic precipitation smoke filter comprising said least one removable cell, said cell comprising ionization wires, collecting electrodes and repelling electrodes, said wires and electrodes being supplied with an electrical power, wherein the method comprises at least the step of passing hot air through said wet removable cell, while said cell is positioned inside the electrostatic precipitator and while said cell is switched off, and wherein said hot air is generated by the coffee beans roasting apparatus while the roasting chamber of said apparatus is empty, in particular void of coffee beans.

2. Method according to claim 1 wherein, while passing hot air through the at least one cell of the electrostatic precipitator, said method comprises the steps of: S1—keeping the at least one cell of the electrostatic precipitator switched off during one first pre-determined period, then S2—at the end of said first pre-determined period, electrically switching on said cell, and if short-circuit is detected during a second pre-determined period, implementing steps S1 and S2 again, if no short-circuit is detected during the second pre-determined period, finishing the operation of passing air through the cell.

3. Method according to claim 1, wherein the electrostatic precipitator comprises several cells and, during step S2, each cell is successively switched on in order to detect short circuit on at least one cell.

4. Method according to claim 2, wherein: if no short-circuit is detected during step S2, an intermediate checking step S3 is implemented before finishing the operation of passing air through the at least one cell, wherein during said intermediate checking step S3 hot air is passed through the cell of the electrostatic precipitator while said cell is switched on, and if short-circuit is detected during step S3, steps S1 and S2 are implemented again.

5. Method according to claim 2, wherein the step of finishing the operation of passing hot air through the cell comprises the step of passing cooling air through the cell.

6. Method according to claim 1 wherein the smoke treating unit comprises an active carbon filter and/or at least one metallic mesh filter.

7. Method according to claim 1 wherein: the smoke treating unit comprises an active carbon filter, and hot air is passed through the cell while keeping the temperature of the active carbon filter at at most 65° C.

8. A system of a coffee beans roasting apparatus and a smoke treating unit, wherein said smoke treating unit comprises a smoke driver and at least an electrostatic precipitator, said electrostatic precipitator comprising at least one removable cell of associated wires and plates, and wherein said coffee beans apparatus comprises a heating device, and wherein said system comprises a control system operable to control: the heating device of the roasting apparatus, the smoke driver of the smoke treating unit, and the electrical switching of the at least one cell of the electrostatic precipitator.

9. A system of a coffee beans roasting apparatus and a smoke treating unit according to claim 8, wherein, during the step of finishing the operation of the drying mode, the control system is configured to deactivate the heating device of the roasting apparatus and to actuate the smoke driver of the smoke treating unit in order to pass cooling air through the at least one cell.

10. A system of a coffee beans roasting apparatus and a smoke treating unit according to claim 8, wherein the smoke treating unit comprises an air inlet configured to introduce ambient air inside the smoke filtering sub-unit.

11. A system of a coffee beans roasting apparatus and a smoke treating unit according to claim 8, wherein the smoke treating unit comprises an active carbon filter, and the control system of the system is configured to operate the heating device of the roasting apparatus and the smoke driver of the smoke treating unit to maintain the temperature of the active carbon filter at at most 65° C.

12. A computer program comprising instructions which, when executed by a computer, processor or control unit, cause the computer, processor or control unit to perform the method of to dry at least one wet removable cell of an electrostatic precipitation smoke filter of a smoke treating unit of a roasting system, said system comprising: a roasting apparatus, a smoke treating unit configured to treat the smoke produced by the roasting apparatus, said smoke treating unit comprising said electrostatic precipitation smoke filter, said electrostatic precipitation smoke filter comprising said least one removable cell, said cell comprising ionization wires, collecting electrodes and repelling electrodes, said wires and electrodes being supplied with an electrical power, wherein the method comprises at least the step of passing hot air through said wet removable cell, while said cell is positioned inside the electrostatic precipitator and while said cell is switched off, and wherein said hot air is generated by the coffee beans roasting apparatus while the roasting chamber of said apparatus is empty, in particular void of coffee beans.

13. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Specific embodiments of the invention are now described further, by way of example, with reference to the following drawings in which:

[0095] FIG. 1 is a view of a system of a roasting apparatus and a smoke treating unit illustrating the path of the smoke or of hot air through the system,

[0096] FIG. 2 is a view illustrating the removal of two cells of the electrical precipitator from the smoke treating unit,

[0097] FIG. 3 is a detailed view of the collecting device and the air inlet of the system of FIG. 1,

[0098] FIG. 4 is a block diagram of the controller of a system according to the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0099] System for Roasting and Filtering

[0100] FIGS. 1 and 2 show 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.

[0101] Roasting Apparatus

[0102] The roasting apparatus 1 is operable to receive and roast coffee beans inside a roasting chamber 12.

[0103] 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 a heating device 13, usually comprising 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] The rest of the smoke is evacuated through the smoke outlet 11 at the top of the roasting apparatus.

[0110] Smoke Treating Unit

[0111] The smoke treating unit 2 is operable to receive and treat the smoke A1 emitted at the smoke outlet 11 of the roasting apparatus.

[0112] First, the smoke treating unit 2 comprises a smoke collecting device 21 adapted to collect the smoke or hot air produced by the roasting apparatus. This smoke collecting device 21 is particularly illustrated in the exploded view of FIG. 2: the collecting device forms an internal void space guiding the smoke or air (dotted lines A1, A2, A3) from the outlet 11 of the roasting apparatus in direction of the smoke filtering sub-unit 22. In FIG. 2, it can be appreciated that the bottom part of the smoke collecting device comprises a hole 211 designed to cooperate in a loose manner with the smoke outlet 11 of the roasting apparatus, the hole 211 being quite larger than the cross section of the smoke outlet end of the roasting apparatus. Generally, the bottom part of the smoke collecting device is simply put above the top of the roasting unit without any fixing means. This is particularly practical when the roasting unit 1 and the smoke treating unit 2 are two separated module. The smoke treating unit 2 can be easily connected or disconnected from any roasting apparatus.

[0113] The collecting device comprises a smoke outlet 212 cooperating with a guiding duct 27 conducting the smoke to the second part of the smoke treating unit that is the smoke filtering sub-unit 22. In the illustrated embodiment, the guiding duct 27 is designed to bring the smoke or air downwards in order to pass through the different filtering device from the bottom to the top. Yet, in other non-illustrated embodiments, the guiding duct can be designed to guide the smoke to pass through the different filtering devices from the top to the bottom.

[0114] In the illustrated embodiment, the smoke filtering sub-unit 22 is positioned close and aside the roasting apparatus.

[0115] Secondly, the smoke filtering sub-unit 22 comprises an electrostatic precipitator 222 adapted for filtering small particulate matter PM.sub.2.5. As illustrated in FIG. 3, the electrostatic precipitator comprises two cells 222a, 222b that can be removed from the smoke filtering unit for cleaning. Once washed with water and drained, they can be put back inside the smoke treating unit and the drying method can be implemented.

[0116] In this particular illustrated embodiment, the smoke filtering sub-unit 22 comprises also: [0117] an active carbon filter 221 adapted to remove VOCs from the smoke, [0118] other filters for particulate matter such as a device 223 adapted for filtering large particulate matter PM.sub.10 (for example HEPA filter, metallic filter, paper filter).

[0119] Preferably, the devices for removing particulate matters are positioned upstream the active carbon filter. This upstream position guarantees that particulate matter do not foul the active carbon filter.

[0120] 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.

[0121] Thirdly, the smoke filtering sub-unit 22 comprises a smoke driver 23, generally a fan, for sucking the contaminated smoke or hot air from the inlet 211 of the collecting device through the smoke filtering sub-unit 22, where it is passed, to the outlet 25 of the smoke filtering sub-unit 22, where it is dispensed in ambient atmosphere.

[0122] Control System of System

[0123] With reference to FIGS. 1, 3 and 4, the control system 3 will now be considered: the control system 3 is operable to control the components of the roasting apparatus 1 and smoke treating unit 2 to dry the pairs of cell 222a, 222b. The control system 3 typically comprises: a user interface 32, a processing unit 30, a temperature sensor 26, a power supply 33, a memory 31.

[0124] The control system of the smoke treating unit 2 can be independent (when used in a manual mode) from the control system of the roasting apparatus or preferably, the control system of the smoke treating unit 2 can be connected to the control system of the roasting apparatus, the control system of the roasting apparatus being the master and the control system of the smoke treating unit being the slave.

[0125] The user interface 32 comprises hardware to enable an end user to interface with the processor 30 and hence is operatively connected thereto. More particularly: the user interface receives commands from a user; a user interface signal transfers the said commands to the processor 30 as an input. The commands may, for example, be an instruction to execute a drying process. The hardware of the user interface 32 may comprise any suitable device(s), for example, the hardware comprises one or more of the following: buttons, such as a joystick button or press button, joystick, LEDs, graphic or character LDCs, graphical screen with touch sensing and/or screen edge buttons.

[0126] When the control system of the smoke treating unit is the slave of the control system of the roasting apparatus, the user interface of the roasting apparatus can be used as the common interface of both apparatuses, input and output for the smoke treating unit being managed from that common interface. For example, progress about the process of drying of the smoke treating unit can appear on the user interface of the roasting apparatus.

[0127] Sensor 26 is operatively connected to the processor 30 to provide an input for monitoring the drying process. In particular, the sensor 26 provides the controller with input about the temperature upstream the active carbon filter 221. Other optional sensors may be implemented like VOC or PM detection sensors to detect malfunction during the drying mode, for example, presence of coffee beans inside the chamber of roasting apparatus.

[0128] The processor 30 generally comprises memory, input and output system components, which are arranged as an integrated circuit, typically as a microprocessor or a microcontroller. The processor 30 may comprise other suitable integrated circuits, such as: an ASIC, a programmable logic device such as an FPGA, an analogue integrated circuit such as a controller. The processor 30 may also comprise one or more of the aforementioned integrated circuits, i.e. multiple processors.

[0129] The power supply 33 is operable to supply electrical energy to at least the processor 30, any filtering device requiring power like the electrostatic precipitator and its pairs of cells 222a, 222b, the smoke driver 23 and the heating device of the roasting apparatus.

[0130] The memory unit 31 is generally configured for storage of the program code and optionally data. In particular, the program code encodes a drying process. The memory unit typically comprises: a non-volatile memory e.g. EPROM, EEPROM or Flash for program code and operating parameter storage, volatile memory (RAM) for data storage. The memory unit 31 may comprise separate and/or integrated (e.g. on a die of the processor) memory. For programmable logic devices the instructions can be stored as programmed logic.

[0131] In particular, the instructions stored on the memory unit 19 can be idealised as comprising a program of the drying process of the cells of the electrostatic precipitator.

[0132] The control system 3 is operable to apply this drying process program by controlling the heating device 13 of the roasting apparatus, the smoke driver of 23 of the smoke treating unit and the switches 29a, 29b of the cell of the electrostatic precipitator based on the detector 28 of short-circuits and optionally the temperature sensor 26.

[0133] The program can effect control of said components using extraction information encoded on a code and and/or other information that may be stored as data on the memory unit 19 and/or input via the user interface 20 and/or signal of the detector 28 of short-circuits and optionally the temperature sensor 26.

[0134] In particular, the control system 3 is configured to produce hot air in the roasting apparatus and drive this hot air through the pairs of cell of the electrostatic precipitator while keeping these cells switched off until the cells are dried and no humidity creates short-circuits in the cells.

[0135] The processing unit 30 is operable to: [0136] receive an input from the user interface 32 that drying of the cells 222a, 222b of the electrostatic precipitator positioned inside the electrostatic precipitator is requested, [0137] process the input according to the smoke treating program code (or programmed logic) stored on the memory unit 31, [0138] provide an output, which comprises the control of the heating device 13 of the roasting apparatus, of the smoke driver 23 and of the switches 29a, 29b of the cells of the electrostatic precipitator.

[0139] In particular, the output consists in: [0140] in a first step S1, actuating the heating device 13 of the roasting apparatus to generate hot air and actuating the smoke driver 23 to pass this flow of hot air through the cells 222a, 222b, while keeping the cell of the electrostatic precipitator switched off, during a first pre-determined period, [0141] in a second step S2, at the end of the pre-determined period, electrically switching on the cell 222a and detecting any short-circuit, and then electrically switching on the cell 222b and detecting any short-circuit, then [0142] if at short-circuit is detected, implementing steps S1 and S2 again, and if no short-circuit is detected, finishing the operation of passing air through the cells.

[0143] In a preferred embodiment, the drying process comprises a control of the temperature inside the smoke treating unit, in particular if this unit comprises an active carbon filter 221 such as illustrated in FIG. 1. In that preferred embodiment, in addition to the above mentioned steps, the processing unit 30 can be operable to: [0144] receive an input of the temperature sensor 26, [0145] process the input according to smoke treating program code (or programmed logic) stored on the memory unit 31, [0146] provide an output, which comprises the control of the smoke driver 23. The process is more preferably executed with closed-loop control using the input signal from the temperature sensor 26 as feedback. In that step, the processing unit can control the heating device of the roasting apparatus too, e.g. decrease the power of the heater.

[0147] If the temperature becomes too high, the speed of the fan of the smoke driver 23 is increased to introduce a more important volume of ambient air A at the air inlet 24 and to mix more ambient air with the hot air A1 with the effect of decreasing the temperature of the flow of hot air A2.

[0148] Alternatively, if the temperature becomes too low, the speed of the fan of the smoke driver 23 is decreased to introduce a less important volume of ambient air A at the air inlet 24 and to mix less air with the hot air A1 with the effect of increasing the temperature of the hot air A2 passed through the smoke filtering sub-unit 22.

[0149] With the system such as illustrated in the figures, the drying method was implemented with [0150] the roasting apparatus producing hot air at 200° C., [0151] the smoke driver driving hot air to get a temperature of about 60° C. downstream the electrostatic precipitator 222 [0152] the step S1 happening until a first pre-determined period of 5 minutes, [0153] the step S2 happening during a pre-determined period of 5 seconds, [0154] the checking step S3 happening during a pre-determined checking period of 2 minute.

[0155] Depending on the state of wetting of the cells, drying was reached in 10 to 30 minutes.

[0156] The method of the present invention presents the advantage of enabling the cleaning of the smoke treating unit of a roasting apparatus very rapidly, decreasing the non-operational state of the smoke treating unit from several hours to less than half an hour.

[0157] In addition the method enables the drying of other filters part of the smoke treating unit simultaneously.

[0158] 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.

[0159] 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.

[0160] 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”.

TABLE-US-00001 List of references in the drawings: roasting apparatus 1 smoke outlet 11 roasting chamber 12 top outlet 121 heating device 13 temperature sensor 14 smoke treating unit 2 smoke collecting device 21 smoke inlet 211 smoke outlet 212 smoke filtering sub-unit 22 active carbon filter 221 electrostatic precipitator 222 cells 222a, 222b PM filter 223 smoke driver 23 air inlet 24 outlet 25 temperature sensor 26 guiding duct 27 short-circuit detector 28 switch of cell 29a, 29b controller 3 processing unit 30 memory unit 31 user interface 32 power supply 33 system 100