Systems for roasting coffee particles

Abstract

A system (100) for roasting coffee particles is described, comprising: a combustion chamber (1) capable of heating air; a rotating drum (3) for roasting coffee particles; a first connecting duct (4) between the combustion chamber (1) and the rotating drum (3) for allowing hot air to travel from the combustion chamber (1) to the rotating drum (3) along a feed direction (V); a decanting cyclone separator (8) connected to the rotating drum (3) by a second duct (9) to receive a hot air flow mixed with air and / or solid impurities from the rotating drum (3) and formed during roasting; the system (100) also includes a tubular body (10) having two channels (11, 12) positioned on the first connecting duct (4) between the combustion chamber (1) and the rotating drum (3); the tubular body (10) is equipped with a first valve (13) and a second valve (14) to change the temperature of the mixed air flow entering the rotating drum (3).

Description

Technical Field

[0001] The present invention relates to a system for roasting coffee particles, in particular for roasting green coffee particles. Background Art

[0002] Systems have been used for some time in the roasting process of green coffee particles, which systems are capable of generating heat that impinges on the particles at a predetermined temperature to roast the particles by various methods such as convection, contact / conduction or radiation.

[0003] Currently, the most common process is by convection with hot air, since the coffee particles avoid direct contact with the heat source, allowing a uniformly roasted product. The coffee particles are then cooled (using ambient air or forced air) to allow the aroma to be enhanced.

[0004] The main components of a system for roasting coffee particles by convection are:

[0005] - a combustion chamber for heating the air (having a burner designed to heat the air present inside the combustion chamber);

[0006] - a hopper for feeding green coffee particles;

[0007] - a rotating drum for roasting coffee particles (including screws or wings for rotating the product), connected on one side to a hopper for feeding the particles to be roasted and on the other side to a combustion chamber by means of suitable ducts for the flow of hot air for roasting the particles;

[0008] - a tank for cooling the roasted granules, equipped with suitable channels to discharge the roasted granules from the drum;

[0009] - a decanting cyclone connected to the roasting drum so as to receive a flow of hot air coming from the drum mixed with air and / or solid impurities, i.e. solids separated from the coffee particles during the roasting step (e.g. films or particles of impurities); the cyclone is also equipped with a duct for discharging and outflowing the air flow with impurities to the outside of the system.

[0010] From patent document EP 3 178 330 a system very similar to the one just described above for roasting coffee is known.

[0011] The various components of the system are equipped with temperature probes connected to a control unit to measure the operating temperatures inside the combustion chamber, the connecting pipes, the roasting drum and the decanting silo and to modify them according to the operating steps used to roast the coffee particles.

[0012] This check is necessary since the roasting cycle must include a step of "drying" the particles, which must be performed in a sufficiently fast way so that the moisture present inside the coffee particles evaporates (the particles lose weight and increase volume) and humidifies the surroundings, i.e. the rotating drum allows a more delicate contact of the coffee particles with the drum itself and does not allow, during the actual roasting step, the so-called "burning" phenomenon, i.e. the loss of surface material due to excessive contact with the metal walls of the rotating cylinder, which results in the appearance of small blackened areas on the surface of the particles.

[0013] Next comes the actual step of roasting the pellets, which must occur with a gradual and constant increase in the pellet's internal temperature to obtain optimal roasting.

[0014] In other words, the air must first enter the drum and remain at a high temperature in the drum (at least 300 / 400°) to dry the particles; the temperature inside the drum must then be reduced (approximately 200-220°) in order to obtain correctly roasted particles within a variable processing time depending on the type of particles present.

[0015] However, the above-described type of baking systems have several disadvantages based on the procedure.

[0016] The presence of a gas burner for generating a hot air flow directed towards the drum requires a relatively long reaction time in order to effect the temperature change to be performed inside the drum.

[0017] This factor, combined with the precise time required for a proper roasting process and the aforementioned temperatures, may determine that the roasting quality of the pellets is poor.

[0018] Furthermore, the step of drying the particles determines the generation of a large amount of fumes (ie, air with a high impurity rate), which are directed to a decanter cyclone for purification.

[0019] In this case, in order to obtain a correct purification of the environment, it is necessary to increase the temperature of the air flow to incinerate the impurities, but usually during this step the burner must reduce the temperature to allow a correct roasting of the particles.

[0020] However, an increase in temperature may determine that the process of roasting coffee particles is not correct.

[0021] For this purpose, the outflow duct must be equipped with one or more catalytic filters in order to retain the solid particles and discharge clean air without having to increase the air temperature.

[0022] The presence of these catalytic filters actually increases the overall cost of the system and necessitates regular inspection of the filters more frequently than normal inspections of the system would otherwise be performed. Summary of the invention

[0023] The object of the present invention is to provide a system for roasting coffee particles which overcomes the above-mentioned disadvantages of the prior art.

[0024] More specifically, an object of the present invention is to provide a system for roasting coffee particles capable of preventing thermal transients in the roasting drum, ie maintaining the desired air temperature in a regular and continuous manner.

[0025] Another object of the present invention is to provide a system for roasting coffee particles that makes it possible to speed up the roasting step while maintaining a high final quality of the product and at the same time reduce the overall costs of the system and its maintenance.

[0026] These objects are fully achieved by the system for roasting coffee particles according to the present invention as characterized in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The main features of the present invention will become more apparent from the following detailed description of a preferred non-limiting embodiment thereof, illustrated by way of example in the accompanying drawings, in which:

[0028] - Figure 1 is a schematic diagram of a baking system according to the present invention;

[0029] - Figure 2 is relative to Figure 1 A schematic front view of a T-shaped tubular body with a valve element, in which some parts are shown in cross-section and others are cut away to better illustrate some technical details;

[0030] - Figures 3 to 5 Shows Figure 2 Corresponding schematic sectional views of a cylindrical tubular body in corresponding operating positions of the valve element inside the tubular body. DETAILED DESCRIPTION

[0031] With reference to the accompanying drawings, in particular Figure 1 , a system according to the invention, generally designated 100, is used for roasting green coffee particles.

[0032] The main components of the system 100 include a combustion chamber 1 equipped with a unit 2 for generating heat capable of heating the air (for example, but without limiting the scope of the invention, a gas burner).

[0033] The system 100 further comprises a rotating drum 3 for roasting the coffee particles.

[0034] The system 100 comprises a first duct 4 for connecting between the combustion chamber 1 and the rotating drum 3 so that hot air travels in a feed direction V from the combustion chamber 1 to the rotating drum 3 .

[0035] The system 100 further comprises a decanting cyclone 8 connected to the rotating drum 3 via a second conduit 9 so as to receive a hot air flow coming from the rotating drum 3 and mixed with air and / or solid impurities formed during roasting.

[0036] As shown, the system 100 also comprises at least one hopper 5 for feeding the particles to be roasted, which hopper 5 is connected to the rotating drum 3 .

[0037] Furthermore, the system 100 comprises a tank 6 for cooling the roasted particles, which tank 6 is equipped with a channel 7 for discharging the roasted particles from the rotating drum 3 .

[0038] As shown again in the figures, the system 100 comprises a tubular body 10 having two channels 11 , 12 positioned on a first duct 4 for connecting between the combustion chamber 1 and the rotating drum 3 .

[0039] The tubular body 10 is equipped with a first valve 13 and a second valve 14, thereby intercepting the hot air flow from the combustion chamber 1 on the first channel 11 and using the first valve 13, and the second channel 12 and the second valve 14 are configured to intercept air outside the system 100, the temperature of the air outside the system 100 being lower than the temperature of the air flow arriving from the combustion chamber 1, and feeding it into the first pipe 4 downstream of the first valve 11 relative to the feeding direction V, thereby changing the temperature of the mixed air flow entering the rotating drum 3.

[0040] The control device 15 is connected to the first valve 13 and the second valve 14 for changing their positions in the corresponding first passage 11 and the second passage 12 , thereby changing the flow rates of the corresponding air flows according to the desired temperature inside the rotating drum 3 .

[0041] In other words, the correct baking temperature inside the rotating drum can be obtained regardless of the temperature inside the combustion chamber.

[0042] In this way, the combustion chamber can be operated in a constant steady state, since the temperature in the drum is regulated downstream of the combustion chamber by means of a two-way system present on the first duct with corresponding valves.

[0043] As shown, the control device 15 has means 16 for connecting to the first valve 13 and the second valve 14 so that the first valve 13 and the second valve 14 are moved simultaneously between several intermediate operating positions (in Figure 4 These intermediate operating positions are comprised between a first end operating position and a second end operating position, in which the first valve 13 is positioned so as to completely close the first duct 4 for feeding the air flow from the combustion chamber 1, and at the same time, the second valve 14 is positioned so as to keep the second channel 12 ( Figure 3) is fully opened, in the second end operating position, the first valve 13 is positioned so as to keep the first duct 4 for feeding the air flow from the combustion chamber 1 fully open, and at the same time, the second valve 14 is positioned so as to completely close the second channel 12 ( Figure 5 ).

[0044] In this way, the temperature can be reduced from the rapid cooling of the rotating drum ( Figure 3 The valve structure) adjusts to the rapid heating of the drum ( Figure 5 valve structure), or using Figure 4 The configuration shown modifies the temperature in the rotating drum in a modulated manner.

[0045] It should be noted that the tubular body 10 with the two channels 11 , 12 is of "T" type, being provided with two channel sections having a circular cross section.

[0046] In view of this, the first section of the channel 11 defines a coaxial joint on the first connecting duct 4 between the combustion chamber 1 and the rotating drum 3 (see Figure 2 ).

[0047] In an exemplary non-limiting embodiment according to the present invention, each of the first valve 13 and the second valve 14 is of a butterfly type and is each formed by a circular plate hinged on the corresponding first channel 11 and the second channel 12 so as to be rotatable about a central axis.

[0048] Preferably, the control device 15 comprises an actuator 17 (for example, an actuator of electromechanical type, and Figure 2 ), the actuator 17 is associated with the tubular body 10 and is provided with means 16 for connecting to the first valve 13 and the second valve 14 to allow the first valve 13 and the second valve 14 to move simultaneously.

[0049] In view of this, an actuator 17 is externally associated to the second channel 12 and is equipped with connection means 16 comprising a motor-driven shaft 18 connected to the second valve 14 to allow a controlled rotation of the second valve 14 .

[0050] The end of a first connecting rod 19 is keyed to the shaft 18, which in turn is hinged to a shaft 20 for driving and connecting to a second connecting rod 21, which is connected to the first valve 13, so that a single activation of the shaft 18 driven by the motor allows the first valve 13 and the second valve 14 to move simultaneously.

[0051] The system 100 also comprises a suction unit 22 associated with the decanting cyclone 8 and configured for air recirculation in order to pick up impurities in the air coming from the decanting cyclone 8 and convey them to the combustion chamber 1 using a third duct 23 to allow the recovery of waste heat arriving from the rotating drum 3 and to reduce the solid particles present through an exhaust flue 24 made in the combustion chamber 1.

[0052] It should be noted that the suction unit 22 creates a negative pressure circuit in the form of a compound closed circuit at least from the first duct 4 , from the rotating drum 3 and from the decanting cyclone 8 to allow a constant and correct flow of hot air from the first duct 4 and / or ambient air.

[0053] The system 100 also comprises a unit 25 for assisting the introduction of air into the combustion chamber 1 , in order to obtain, if necessary, a step of post-combustion of the fumes to be directed towards the exhaust duct 24 .

[0054] Furthermore, the system 100 comprises a command and control unit 26 connected at least to the combustion chamber 1 and to the first valve 13 and the second valve 14 to allow the air flow inside the rotating drum 3 and its temperature to be regulated.

[0055] In view of this, the command and control unit 26 is connected to at least a first temperature sensor 27 positioned inside the combustion chamber 1 , a second temperature sensor 28 connected to the first connecting duct 4 positioned downstream of the tubular body 10 , and a third temperature sensor 29 positioned inside the rotating drum 3 .

[0056] In this way, the command and control unit 26 is always updated on the existing operating temperature and can, for example, modify the position of a valve, or increase or decrease the temperature in the combustion chamber if necessary.

[0057] A system constructed in this way brings many advantages, including:

[0058] - Optimization of the baking cycle thanks to precise control of the air flow inside the drum and its temperature;

[0059] - the combustion chamber is isolated from the baking drum thanks to the valve on the first duct, thus allowing to maintain a high and constant temperature in the combustion chamber;

[0060] - The presence of a negative pressure system makes it possible to optimize and speed up the incoming and outgoing air flows by using a system for discharging the air flow with impurities directly into the combustion chamber, thanks to the possibility of having an afterburner, which allows to directly reduce the particles and the relative emissions towards the flue due to the presence of high temperatures.

[0061] The latter feature allows the system to be operated without a catalytic filter.

Claims

1. A system (100) for roasting coffee particles, comprising at least: - a combustion chamber (1) equipped with a unit (2) for generating heat capable of heating the air; - a rotating drum (3) for roasting coffee particles; - a first duct (4) for connecting between the combustion chamber (1) and the rotating drum (3) for passing hot air from the combustion chamber (1) to the rotating drum (3) in a feeding direction (V); - a tubular body (10) having two channels (11, 12) on a first duct (4) positioned between the combustion chamber (1) and the rotating drum (3); the tubular body (10) is equipped with a first valve (13) and a second valve (14) so ​​that the hot air flow from the combustion chamber (1) is intercepted on the first channel (11) and with the first valve (13), and the second channel (12) and the second valve (14) are configured to intercept air outside the system (100) whose temperature is lower than that of the air flow arriving from the combustion chamber (1) and feed it into the first duct (4) downstream of the first valve (13) with respect to the feeding direction (V), thereby changing the temperature of the mixed air flow entering the rotating drum (3); - a control device (15) connected to the first valve (13) and the second valve (14) for changing their position inside the respective first channel (11) and the second channel (12), thereby changing the flow rate of the respective air flow according to the desired temperature inside the rotating drum (3); wherein the control device (15) has a connection device (16) for connecting to the first valve (13) and the second valve (14) so ​​that the first valve (13) and the second valve (14) are simultaneously moved between a plurality of intermediate operating positions, the intermediate operating positions being between a first end operating position and a second end operating position, in which the first end operating position the first valve (13) is positioned so as to completely close the first duct (4) for feeding the air flow from the combustion chamber (1), and at the same time the second valve (14) is positioned so as to keep the second channel (12) completely open, and in which the first end operating position the first valve (13) is positioned so as to keep the first duct (4) for feeding the air flow from the combustion chamber (1) completely open, and at the same time the second valve (14) is positioned so as to completely close the second channel (12), The system comprises a decanting cyclone separator (8), which is connected to the rotating drum (3) via a second pipe (9) so as to receive a hot air flow mixed with air and / or solid impurities from the rotating drum (3) and formed during roasting. Therein, the system comprises a suction unit (22) associated with the decanting cyclone (8) and configured for air recirculation in order to pick up impurities from the air coming from the decanting cyclone (8) and convey them to the combustion chamber (1) using a third duct (23) to allow recovery of waste heat arriving from the rotating drum (3) and reduction of solid particles through an exhaust flue (24) made in the combustion chamber (1).

2. The system according to claim 1, characterized in that The tubular body (10) with two channels (11, 12) is "T" shaped, provided with two channel sections with circular cross-section; the first section of the channel (11) defines a coaxial joint on the first duct (4) for connection between the combustion chamber (1) and the rotating drum (3).

3. A system according to any one of the preceding claims, characterised in that Each of the first valve (13) and the second valve (14) is of a butterfly type and is formed by a circular plate hinged to the corresponding first passage (11) and the second passage (12) so as to be rotatable about a central axis.

4. The system according to claim 1, characterized in that The control device (15) comprises an actuator (17) associated with the tubular body (10) and equipped with connection means (16) for connecting to the first valve (13) and the second valve (14) so ​​as to allow the first valve (13) and the second valve (14) to move simultaneously.

5. The system according to claim 4, characterized in that The actuator (17) is externally associated with the second channel (12) and is equipped with a connection device (16), which includes a motor-driven shaft (18) connected to the second valve (14) to allow the second valve (14) to be rotated in a controlled manner; the end of a first connecting rod (19) is keyed to the shaft (18), the end of the first connecting rod (19) being hinged on a shaft (20), the shaft (20) being used to drive and connect to a second connecting rod (21), the second connecting rod (21) being connected to the first valve (13), thereby allowing the first valve (13) and the second valve (14) to move simultaneously through a single activation of the motor-driven shaft (18).

6. The system according to claim 1, characterized in that The suction unit (22) generates a negative pressure circuit in the form of a composite closed circuit from the combustion chamber (1), from the rotating drum (3) and from the decanting cyclone (8) to allow a constant and correct flow of hot air and / or ambient air from the first duct (4).

7. The system according to claim 1, characterized in that It comprises a unit (25) for assisting the introduction of air into said combustion chamber (1) in order to obtain, if necessary, a step of post-combustion of the flue gases to be directed to an exhaust duct (24).

8. The system according to claim 1, characterized in that It comprises a command and control unit (26) which is connected at least to the combustion chamber (1) and the first valve (13) and the second valve (14) to allow the air flow inside the rotating drum (3) and its temperature to be regulated; the command and control unit (26) is connected at least to a first temperature sensor (27) positioned inside the combustion chamber (1), to a second temperature sensor (28) positioned on the first duct (4) downstream relative to the tubular body (10), and to a third temperature sensor (29) positioned inside the rotating drum (3).

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