Method and apparatus for processing incoherent plastics

Abstract

An apparatus and a method for processing incoherent plastics are disclosed, in which a first process stage comprises a first container (2) of incoherent plastics and a first gas circuit (4) for supplying a first process gas to the first container, in which a second process stage comprises a second container (3) that receives incoherent plastics exiting the first container and a second gas circuit (5) for supplying a second process gas to the second container, and in which a first bypass flow from the first gas circuit to the second gas circuit and a second bypass flow from the second gas circuit to the first gas circuit are generated simultaneously in order to increase the energy in order to increase the energy efficiency of the process.

Description

Method and apparatus for processing incoherent plasticsBackground of the invention

[0001] The invention relates to a method and an apparatus for processing incoherent plastics, i.e. in the shape of granules and / or micro-granules and / or pellets and / or powder and / or flakes or the like, in particular for removing (dehumidifying and / or drying) water from the incoherent plastics so that the processed incoherent plastics reach a user machine with a desired degree of humidity.

[0002] Specifically but not exclusively, the invention can be usefully applied in various plastics transformation sectors, like injection, extrusion, thermoforming, calendering, etc.

[0003] In particular, reference is made to a process that involves at least two process stages arranged in line one after the other.

[0004] Processing incoherent plastics by two process stages is already known, for example from patent application US 2021 / 276224 Al, which shows a process for drying granular polymer material that is dehumidified by a first gas flow at a first temperature comprised between 100°C and 150°C, heated to a second temperature greater than the first temperature and dried to the second temperature by applying a set vacuum level

[0005] One of the aspects of the prior art that is improvable is increasing the overall energy efficiency of the process in the two treatment stages.

[0006] Another need is to ensure that the processed incoherent plastics have the desired and suitable features (for example degree of humidity) in function of the user machine (extruder, press, etc).

[0007] It would also be desirable to reduce treatment time, in particular the overall dwell time of the incoherent plastics in the two treatment stages, as well as increase the total energy transfer to the incoherent plastics during the entire process.Summary of the invention

[0008] One object of the invention is to provide a solution that is able to overcome the aforesaid limits and drawbacks of the prior art.

[0009] One object of the invention is to make a solution for processing incoherent plastics available that is an alternative to those of the prior art.

[0010] One object of the invention is to propose a suitable solution for controlling the extraction of humidity from incoherent plastics.

[0011] One advantage is reducing the risk of downtime due to the fact that a user machine for transforming plastics is supplied with incoherent plastics of unsuitable quality.

[0012] One advantage is reducing total treatment time, in particular the dwell time of the incoherent plastics in the various treatment stages.

[0013] One advantage is making a constructionally cheap and simple apparatus for processing incoherent plastics.

[0014] Such objects and advantages and still others are achieved by an apparatus and / or a method according to one or more of the claims set out below.

[0015] In one embodiment, an apparatus for processing incoherent plastics comprises a first process stage with a first container of the incoherent plastics and a first gas circuit for supplying a first process gas to the first container, a second process stage with a second container for receiving incoherent plastics from the first container and a second gas circuit for supplying a second process gas to the second container, and means for generating a first bypass flow from the first gas circuit to the second gas circuit and simultaneously a second bypass flow from the second gas circuit to the first gas circuit.

[0016] The second process stage may comprise, in particular, a dehumidifying device configured to dehumidify the second process gas, for example a dehumidifying device with adsorption separating means or a dehumidifying device with dehumidifying wheel.

[0017] The second process stage may comprise, in particular, a dehumidifying device configured to dehumidify the second process gas, for example a dehumidifying device with injecting means configured to inject into the second gas circuit an auxiliary gas with relatively low humidity content, for example an auxiliary gas with a dewpoint value below -15°C, or below -20°C, or below -25°C, or comprised between -15°C and -80°C. The auxiliary gas may comprise, in particular, nitrogen and / or air. The auxiliary gas may be processed before being injected, to decrease the humidity content. In particular, the auxiliary gas may be dehumidified by a process comprising a step of compressing the auxiliary gas followed by a step of expanding the auxiliary gas. The injection flow of the auxiliary gas may be controlled in function of a humidity value detected in the second process gas. It is in particular possible to activate or increase the injection flow of the auxiliary gas with the increase of the humidity value detected in the second process gas and / or stop or decrease the injection flow of the auxiliary gas as the humidity value detected in the second process gas decreases.

[0018] The first bypass flow and the second bypass flow may be, in particular, equal to each other. The first bypass flow and the second bypass flow may be different from each other, for example, when the first gas circuit is partially open. It is possible to control bypass flows, i.e. the control of the gas flow (in particular, air) exchanged between the firstprocess stage and the second process stage, on the basis of the humidity of the incoherent plastics that were already processed in the first process stage and which have not yet been processed in the second process stage, in particular on the basis of a setpoint value of the aforesaid humidity of the incoherent plastics between the two process stages.

[0019] The first gas circuit may comprise, in particular, an open or partially open circuit, in which at least one part of the first process gas that is supplied to the first container comprises air taken from the outside environment and in which at least one part of the first process gas that is removed from the first container is expelled into the outer environment, so as to expel a certain quantity of humidity into the outer environment and so as to recover relatively non-humid air coming from the outer environment, provided that the ambient humidity is relatively reduced (below the humidity of the first process gas exiting the first container), i.e. on the basis of the external climatic conditions or when the production facility allows a control of environmental conditions.Brief description of the drawings

[0020] The invention can be better understood and implemented with reference to the appended drawings that illustrate an embodiment thereof by way of non-limiting example, in which:Figure 1 is a diagram of an embodiment of an apparatus for processing incoherent plastics, comprising a double process stage, made in accordance with the present invention.Detailed description

[0021] In the aforementioned figure, 1 indicates overall an apparatus for processing incoherent plastics, i.e. in the shape of granules and / or micro-granules and / or pellets and / or powder and / or flakes or the like.

[0022] The apparatus 1 may be used, in particular, to remove water (dehumidifying and / or drying) from the incoherent plastics.

[0023] The incoherent plastics may comprise, in particular, plastics in the form of granules obtained from pelletizing. The incoherent plastics may comprise, in particular, at least one percentage of post-consumption recycled plastics (PCR). The incoherent plastics may comprise, in particular, at least one percentage of post-consumption recycled plastics (PCR) in the form of granules obtained from pelletizing. The incoherent plastics may comprise, in particular, one or more polymers included in the following set: polyethylene terephthalate (PET), polyamide (PA), acrylonitrile butadiene styrene (ABS), polyphenylene sulphide (PPS), polystyrene (PS), polyvinyl chloride (PVC), polysulphone(PSU), polymethylmethacrylate (PMMA), polyolefins in general.

[0024] The apparatus 1 comprises a first container 2 (drying hopper) configured to contain the incoherent plastics. The apparatus 1 comprises a second container 3 (dehumidifying hopper) arranged in line with the first container 2 and configured to receive the incoherent plastics exiting the first container 2. The first container 2 and the second container 3 are connected serially so that the flow of plastics proceeds from the first container 2 to the second container 3. The second container 3 may be arranged below the first container 2, so as to facilitate conveying the material from the first container 2 to the second container 3, or may be arranged alongside the first container 2, in which case it is possible to provide a conveying system that lifts the material from the lower outlet of the first container 2 to the upper inlet of the second container 3.

[0025] The apparatus 1 comprises a plastics entry zone A through which the incoherent plastics enter the first container 2. The apparatus 1 comprises an intermediate zone B in which the incoherent plastics exit the first container 2 and then enters in the second container 3. The apparatus 1 comprises a plastics exit zone C in which the incoherent plastics exit the second container 3. The aforesaid zones A, B and C may be provided, in particular, with conveying means configured to supply the incoherent plastics to the inlet of the first container 2, to transfer the incoherent plastics from the first container 2 to the second container 3 and to remove the exiting incoherent plastics from the second container 3. For each container 2 and 3, it is possible for the incoherent plastics to enter an upper zone of the container and exits a lower zone of the container.

[0026] The apparatus 1 comprises a first gas circuit 4 configured to supply a first process gas to a gas inlet of the first container 2 and to remove used gas from a gas outlet of the first container 2.

[0027] The first gas circuit 4 may be, in particular, a closed circuit, so that the gas removed from the gas outlet of the first container 2 is recirculated to the gas inlet of the first container 2.

[0028] The first gas circuit may comprise, in particular, an open or at least partially open circuit (not shown in the figures).

[0029] When the first gas circuit is partially open, a part of the gas removed from the gas outlet of the first container 2 is recirculated to the gas inlet of the first container 2, whereas another part is expelled into the outer environment, just as a part of the gas that is supplied to the gas inlet of the first container 2 comprises air taken from the outside environment that joins the recirculated gas coming from the gas outlet of the first container2. The air taken from the outside environment will balance the air expelled into the outer environment.

[0030] The apparatus 1 comprises a second gas circuit 5 configured to supply a second process gas to a gas inlet of the second container 3 and to remove used gas from a gas outlet of the second container 3. The second gas circuit 5 may be, in particular, a closed circuit, so that the gas removed from the gas outlet of the second container 3 is recirculated to the gas inlet of the second container 3.

[0031] The apparatus 1 comprises first actuating means 6 configured to control a flow of gas into the first gas circuit 4 and second actuating means 7 configured to control a flow of gas in the second gas circuit 5. The first actuating means 6 may comprise, in particular, at least one first actuator, for example a blower, a pump, or a fan. The second actuating means 7 may comprise, in particular, at least one second actuator, for example a blower, a pump, or a fan.

[0032] Each of the actuating means 6 and 7 may comprise, in particular, a speed variation system, for example a variable drive frequency (VDF), to vary the flow of gas into the first gas circuit 4 and / or into the second gas circuit 5.

[0033] Adjusting the first actuating means 6 and / or the second actuating means 7 enables the flows into the first gas circuit 4 and into the second gas circuit 5 to be differentiated, in particular in function of a bypass value exchanged between the first gas circuit 4 and the second gas circuit 5, as will be explained better below.

[0034] Adjusting the first actuating means 6 and / or the second actuating means 7 enables the transfer of energy between the process gas and the incoherent plastics modified in the first container 2 and / or in the second container 3 to be modified.

[0035] The apparatus 1 comprises bypass means configured to generate simultaneously a first bypass flow from the first gas circuit 4 to the second gas circuit 5 and to second bypass flow, in the opposite direction to the first bypass flow, from the second gas circuit 5 to the first gas circuit 4.

[0036] The bypass means may comprise, in particular, at least two bypass lines 8 and 9 each of which extends between the first gas circuit 4 and the second gas circuit 5. The aforesaid at least two bypass lines may comprise, in particular, a first bypass line 8 that extends between a first point 1-4 of the first gas circuit 4 and a first point 2-5 of the second gas circuit 5 and a second bypass line 9 that extends between a second point 1-5 of the first gas circuit 4 and a second point 2-4 of the second gas circuit 5.

[0037] The first point 1-4 of the first gas circuit 4 may be arranged, in particular,between the gas outlet of the first container 2 and the second point 1-5 of the first gas circuit 4. The second point 2-4 of the second gas circuit 5 may be arranged, in particular, between the gas outlet of the second container 5 and the first point 2-5 of the second gas circuit 5.

[0038] The first actuating means 6 may be, in particular, arranged in the first gas circuit 4 between the gas inlet of the first container 2 and the first point 1-4 of the first gas circuit 4 and / or between the gas inlet of the first container 2 and the second point 1-5 of the first gas circuit 4. The second actuating means 7 may be, in particular, arranged in the second gas circuit 5 between the gas inlet of the second container 3 and the first point 2-5 of the second gas circuit 5 and / or between the gas inlet of the second container 3 and the second point 2-4 of the second gas circuit 5.

[0039] The first point 1-4 of the first gas circuit 4 may be arranged, in particular, before the first actuating means 6, i.e. in a vacuum point that is favorable for mixing the gases of the two gas circuits 4 and 5.

[0040] The bypass means may comprise, in particular, actuating bypass means 10 configured to control the first bypass flow and the second bypass flow. The actuating bypass means 10 may comprise, in particular, one or more flow-adjusting servo valves. In particular, it is possible to arrange a flow-adjusting servo valve in the first bypass line 8 and a flow-adjusting servo valve in the second bypass line 9. It is possible, in particular, to arrange a flow-adjusting servo valve in the first gas circuit 4 after the first bypass line 8 and before the second bypass line 9. It is possible, in particular, to arrange a flow-adjusting servo valve in the second gas circuit 5 after the second bypass line 9 and before the first bypass line 8, where “before” and “after” means with reference to the direction of the flow of gas in the respective circuit. The system of flow-adjusting servo valves is so controlled as to obtain a desired flow in each circuit branch where a respective servo valve is located.

[0041] The actuating bypass means may comprise, in other embodiments, a pumping actuator (for example a blower, a pump, or a fan) operating in each of the two bypass lines 8 and 9, or another pumping system that is suitable for generating the first bypass flow and the second bypass flow.

[0042] The apparatus 1 may comprise, in particular, control means (electronic and programmable, for example an electronic processor) configured to feedback control the first bypass flow and the second bypass flow on the basis of at least one chemi cal -physical feature detected in the plastics exiting the first container 2 (for example the plastics situated in the intermediate zone B). The aforesaid at least one chemical-physical featuremay comprise, in particular, a humidity content detected in the incoherent plastics exiting the first container 2.

[0043] The apparatus 1 may comprise, in particular, control means configured to feedback control the first bypass flow and the second bypass flow on the basis of at least one chemi cal -physical feature detected in the gas in the first gas circuit 4.

[0044] The apparatus 1 may comprise, in particular, control means configured to feedback control the first bypass flow and the second bypass flow on the basis of at least one chemi cal -physical feature detected in the gas in the second gas circuit 5.

[0045] The apparatus 1 may comprise, in particular, control means configured to feedback control the first bypass flow and the second bypass flow on the basis of at least one chemi cal -physical feature detected in the gas in the first bypass line 8.

[0046] The apparatus 1 may comprise, in particular, control means configured to feedback control the first bypass flow and the second bypass flow on the basis of at least one chemi cal -physical feature detected in the gas in the second bypass line 9.

[0047] The second gas circuit 5 may comprise, in particular, adsorption separating means 11 configured to separate at least one substance, in particular water, from the second process gas. The adsorption separating means 11 may comprise, in particular, molecular sieves. The adsorption separating means 11 may comprise, in particular (as in the embodiment in Figure 1), at least two separating units (dehumidifying towers) arranged parallel to one another. The two separating units are so configured as to operate alternately an adsorption step and a regeneration step, so as to ensure a continuous supply of the second process gas to the second container 3.

[0048] In one embodiment that is not illustrated, the adsorption separating means may be arranged in a dehumidifying and / or drying wheel, for example with a rotating drum provided with a honeycomb structure, which rotates the adsorption separating means. During rotation of the adsorption separating means, for example continuous rotation at a controlled (constant) speed, at each revolution the adsorption separating means passes, in sequence, through an adsorption sector in which it is traversed by a process gas, through a regeneration sector in which it is traversed by a regeneration gas, and through a possible cooling sector in which it is traversed by a cooling gas.

[0049] In one embodiment that is not illustrated, the first gas circuit 4 may comprise an injection point at which a flow of a dehumidified gas is injected. The injection point may be arranged, in particular, before the first actuating means 6. The dehumidified and injected gas may be dehumidified so as to reach a dewpoint value comprised between -15°C and -80°C. The dehumidified and injected gas may be, in particular, nitrogen (gas with a very negative dewpoint value).

[0050] The first gas circuit 4 may comprise, in particular, a first heater 12 of the first process gas. In one embodiment that is not illustrated the first heater 12 of the first process gas may be omitted if mixing of the gases between the first gas circuit 4 and the second gas circuit 5 is such as to have a temperature of the mixed gas that is sufficient for treating incoherent plastics in the first stage (in particular for certain polymers that require a relatively reduced treatment temperature, like for example PA, ABS, PE).

[0051] The second gas circuit 5 may comprise, in particular, a second heater 13 of the second process gas.

[0052] In practice, the first container 2 and the first gas circuit 4 define a first process stage, in particular a drying stage, whereas the second container 3 and the second gas circuit 5 define a second process stage, in particular a dehumidifying stage. The second process stage may comprise, in particular, adsorption separating means, whereas the first process stage may be, in particular, devoid of adsorption separating means.

[0053] The apparatus 1 may comprise, in particular, sensor means arranged for detecting one or more operating parameters of the process.

[0054] The sensor means may comprise one or more sensors arranged in the first gas circuit 4 before the first heater 12 (point 1-1). The sensor means may comprise one or more sensors arranged in the first gas circuit 4 after the first heater 12 and before the gas inlet of the first container 2 (point 1-2). The sensor means may comprise one or more sensors arranged in the first gas circuit 4 after the first container 2 (and before the branching of the first bypass line 8) or near or at the gas outlet of the first container 2 (point 1-3). The sensor means may comprise one or more sensors arranged in the first gas circuit 4 near or at branching of the first bypass line 8 (point 1-4). The sensor means may comprise one or more sensors arranged in the first gas circuit 4 at or after the branching of the second bypass line 9 (point 1-5). The sensor means may comprise one or more sensors arranged in the first bypass line 8 (point 1-6).

[0055] The sensor means may comprise one or more sensors arranged in the second gas circuit 5 before the second heater 13 and after the adsorption separating means 11 (point 2-1). The sensor means may comprise one or more sensors arranged in the second gas circuit 5 after the second heater 13 and before the gas inlet of the second container 3 (point 2-2). The sensor means may comprise one or more sensors arranged in the second gas circuit 5 after the second container 3 (and before the branching of the second bypassline 9) or near or at the gas outlet of the second container 3 (point 2-3). The sensor means may comprise one or more sensors arranged in the second gas circuit 5 near or at branching of the second bypass line 9 (point 2-4). The sensor means may comprise one or more sensors arranged in the second gas circuit 5 at or after the branching of the first bypass line 8 and before the adsorption separating means 11 (point 2-5). The sensor means may comprise one or more sensors arranged in the second bypass line 9 (point 2-6).

[0056] The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the first gas circuit 4 and / or at least one temperature sensor of the process gas in the second gas circuit 5 and / or at least one temperature sensor of the process gas in the first bypass line 8 and / or at least one temperature sensor of the process gas in the second bypass line 9.

[0057] The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the first gas circuit 4 and / or at least one flowrate sensor of the process gas in the second gas circuit 5 and / or at least one flowrate sensor of the process gas in the first bypass line 8 and / or at least one flowrate sensor of the process gas in the second bypass line 9.

[0058] The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the first gas circuit 4 and / or at least one dewpoint sensor of the process gas in the second gas circuit 5 and / or at least one dewpoint sensor of the process gas in the first bypass line 8 and / or at least one dewpoint sensor of the process gas in the second bypass line 9. It is possible to determine the dewpoint of the gas and / or another feature indicating a humidity content of the gas, for example relative humidity or absolute humidity.

[0059] The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 1-1. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 1-2. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 1-3. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 1-4. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 1-5. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 1-6. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 2-1. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 2-2. The sensor means may comprise, in particular, at least onetemperature sensor of the process gas in the point 2-3. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 2-4. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 2-5. The sensor means may comprise, in particular, at least one temperature sensor of the process gas in the point 2-6.

[0060] The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 1-1. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 1-2. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 1-3. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 1-4. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 1-5. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 1-6. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 2-1. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 2-2. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 2-3. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 2-4. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 2-5. The sensor means may comprise, in particular, at least one pressure sensor of the process gas in the point 2-6.

[0061] The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 1-1. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 1-2. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 1-3. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 1-4. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 1-5. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 1-6. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 2-1. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 2-2. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 2-3. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 2-4. The sensor means may comprise, inparticular, at least one flowrate sensor of the process gas in the point 2-5. The sensor means may comprise, in particular, at least one flowrate sensor of the process gas in the point 2-6.

[0062] The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 1-1. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 1-2. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 1-3. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 1-4. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 1-5. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 1-6. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 2-1. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 2-2. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 2-3. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 2-4. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 2-5. The sensor means may comprise, in particular, at least one dewpoint sensor of the process gas in the point 2-6.

[0063] The sensor means may comprise, in particular, at least one humidity sensor of the humidity of the incoherent plastics exiting the first container 2 (intermediate or plastics transfer zone B). The sensor means may comprise, in particular, at least one humidity sensor of the humidity of the incoherent plastics exiting the second container 3 (plastics exit zone C).

[0064] The operation of the apparatus 1 may actuate, in particular, a method for processing incoherent plastics. This method comprises the step of introducing incoherent plastics into the first container 2. This method comprises the step of extracting incoherent plastics from the first container 2 and of introducing the aforesaid incoherent plastics into the second container 3. This method comprises the step of supplying a first process gas to an inlet of the first container 2 and of removing used gas from an outlet of the first container 2. This method comprises the step of supplying a second process gas to an inlet of the second container 3 and of removing used gas from an outlet of the second container 3. This method comprises the step of generating simultaneously a first bypass flow, i.e. a flow of process gas that goes from a first gas circuit 4 in which the first process gas flowsto a second gas circuit 5 in which the second process gas flows, and a second bypass flow in an opposite direction to the first bypass flow, i.e. a flow of process gas that goes from the second gas circuit 5 to the first gas circuit 4.

[0065] The processing method may comprise, in particular, the step of controlling through feedback the first bypass flow and / or the second bypass flow on the basis of at least one chemical-physical feature detected in the incoherent plastics exiting the first container 2 (intermediate or plastics transfer zone B to the second container 3). This chemical-physical feature may comprise, in particular, humidity content in incoherent plastics.

[0066] The processing method may comprise, in particular, the step of controlling through feedback the first bypass flow and / or the second bypass flow on the basis of at least one chemi cal -physical feature detected in the gas in the first gas circuit 4.

[0067] The processing method may comprise, in particular, the step of controlling through feedback the first bypass flow and / or the second bypass flow on the basis of at least one chemical-physical feature detected in the process gas in at least one of the bypass lines 8 and 9 between the first gas circuit 4 and the second gas circuit 5.

[0068] The processing method may comprise, in particular, the step of separating at least one substance, in particular water, from the second process gas by the adsorption separating means 11 and / or the step of heating the first process gas and / or the step of heating the second process gas.

[0069] The processing method for processing the incoherent plastics may use, in particular, the following example of a control algorithm.

[0070] The control algorithm adjusts through feedback bypass flow (from the first process stage to the second process stage and, conversely and, in particular, by the same amount, from the second process stage to the first process stage) in function of one or more parameters detected in the process like, for example, the humidity of the incoherent plastics exiting the first container 2 (i.e. the material that has been processed in the first process stage) and / or the dewpoint of the second process gas after mixing with the bypass flow coming from the first gas circuit 4 (point 2-5).

[0071] It has been observed that controlling the aforesaid humidity of the incoherent plastics exiting the first container 2 permits a heat exchange between the process stages so as to achieve great energy efficiency (thus achieving the final objective of obtaining incoherent plastics exiting the apparatus 1 with the desired degree of humidity). Further, controlling the aforesaid dewpoint of the second process gas mixed with the bypass flowfrom the first gas circuit 4, which is substantially the dewpoint of the process gas at the inlet of the adsorption separating means 11 (molecular sieves), enables premature saturation of the adsorption separating means 11 to be avoided.

[0072] In the specific embodiment, the control algorithm adjusts the bypass flow (in particular the same and opposite in the two bypass lines 8 and 9) according to both the parameters, i.e. both the humidity of the incoherent plastics exiting the first container 2 (intermediate zone B), and the dewpoint of the second process gas after mixing with the bypass flow coming from the first gas circuit 4.

[0073] The control algorithm is run iteratively. At the start of an iterative cycle, the humidity of the material of the incoherent plastics exiting the first container 2 (intermediate zone B) is measured and this measured humidity is compared with a set reference value (step 1).

[0074] If the measured humidity exceeds the reference value, the bypass flow is increased (for example, by a set fixed amount).

[0075] If the bypass flow calculated by the control algorithm exceeds a set limit value, a bypass flow is set that is the same as this set limit value. If the bypass flow does not exceed the set limit value, the dewpoint of the second process gas is measured after mixing with the bypass flow (point 2-5) and the measured dewpoint is compared with a set limit value (step 2).

[0076] If the measured dewpoint does not exceed the aforesaid limit value, a new operating cycle starts (step 1). If the measured dewpoint exceeds the aforesaid limit value, then the process continues without modifying the bypass flow.

[0077] If on the other hand returning to step 1, the measured humidity does not exceed the aforesaid reference value, a mixing temperature is measured and the measured mixing temperature is compared with a set limit value (step 3). “Mixing temperature” may either mean the temperature of the first process gas after mixing with the second bypassed process gas (point 1-5), or the temperature of the second process gas after mixing with the first bypassed process gas (point 2-5). If the mixing temperature does not exceed the aforesaid limit value, the bypass flow is increased (for example, by a set fixed amount). If the mixing temperature exceeds the limit value, then the process continues without modifying the bypass flow.

[0078] If the bypass flow, after being increased by the control algorithm, exceeds the aforesaid set limit value, a bypass flow is set equal to the set limit value. If on the other hand the bypass flow, after being increased by the control algorithm, does not exceed theset limit value, it returns to the step 2 seen previously, i.e. the dewpoint of the second process gas is measured after mixing with the bypass flow (point 2-5) and is compared with the set limit value and, if the measured dewpoint does not exceed the limit value, a new operating cycle starts (step 1), whereas if the measured dewpoint exceeds the limit value, then the process continues without modifying the bypass flow.

[0079] Some experimental tests were run using a laboratory apparatus with two process stages that is similar to that of Figure 1.Example 1

[0080] The simulation was run with an hourly production of 100 kg / h of polymer granule with the following process conditions.

[0081] Stage 1 : temperature of the first process gas at the gas inlet of the first heater 12 (point 1-1) = 65°C; setpoint di temperature of the first process gas at the gas inlet of the first container 2 (point 1-2) = 120°C; temperature of the first process gas at the gas outlet of the first container 2 (point 1-3) = 45°C; dewpoint of the first process gas at the gas outlet of the first container 2 (point 1-3) = 10°C; temperature of the polymer granule at the material inlet of the first container 2 (plastics entry zone A) = 25 °C; humidity content in the polymer granule at the material inlet of the first container 2 (plastics entry zone A) = 2100 ppm; temperature of the polymer granule at the material inlet of the first container 2 (intermediate zone B) = 118.4°C; humidity content in the polymer granule at the material inlet of the first container 2 (intermediate zone B) = 1250 ppm.

[0082] A second bypass flow (point 2-6) = 50 m3 / h has been set that flows from the second gas circuit 5 to the first gas circuit 4 along the second bypass line 9. A first bypass flow (point 1-6) has been set that is the same as and opposite the second bypass flow, i.e. a flow of 50 m3 / h that flows from the first gas circuit 4 to the second gas circuit 5 along the first bypass line 8.

[0083] Stage 2: temperature of the second process gas at the gas inlet of the second heater 13 (point 2-1) = 65°C; dewpoint of the second process gas at the gas inlet of the second heater 13 (point 2-1) = -30°C; setpoint value of temperature of the second process gas at the gas inlet of the second container 3 (point 2-2) = 170°C; temperature of the second process gas at the gas outlet of the second container 3 (point 2-3) = 45°C; dewpoint of the second process gas at the gas outlet of the second container 3 (point 2-3) = 10°C; temperature of the polymer granule at the material inlet of the second container 3 (intermediate zone B) = 118°C; humidity content in the polymer granule at the material inlet of the second container 3 (intermediate zone B) = 1250 ppm; temperature of thepolymer granule at the material outlet of the second container 3 (plastics exit zone C) = 168°C; humidity content in the polymer granule at the material outlet of the second container 3 (plastics exit zone C) = 50 ppm.Example 2

[0084] The simulation was run at an hourly production rate of 100 kg / h of polymer granule with the following process conditions.

[0085] Stage 1. Detected values of the first process gas at the gas inlet of the first heater 12 (point 1-1): temperature = 61.3°C; flow = 214 m3 / h; dewpoint = 7.56°C; relative humidity = 4.91%; mass vapor = 1.4460 Kg / h; mass fraction = 6.4133 g / Kg. Detected values of the first process gas at the gas inlet of the first container 2 (point 1-2): temperature = 120°C; flow = 214 m3 / h; dewpoint = 7.56°C; relative humidity = 0.52%; mass vapor = 1.2231 Kg / h; mass fraction = 6.3766 g / Kg. Detected values of the first process gas at the gas outlet of the first container 2 (point 1-3): temperature = 45.0°C; flow = 214 m3 / h; dewpoint = 10.00°C; relative humidity = 12.82%; mass vapor = 1.7943 Kg / h; mass fraction = 7.5750 g / Kg. Detected values of the first process gas at the inlet of the first bypass line 8 (point 1-4): are the same detected values at the gas outlet of the first container 2 (point 1-3). Detected values of the first process gas mixed with the second process gas at the outlet of the second bypass line 9 (point 1-5): temperature = 61.3°C; flow = 214 m3 / h; dewpoint = 7.56°C; relative humidity = 4.91%; mass vapor = 1.4460 Kg / h; mass fraction = 6.4133 g / Kg.

[0086] Stage 2. Detected values of the second process gas at the gas inlet of the second heater 13 (point 2-1): temperature = 65°C; flow = 251 m3 / h; dewpoint = -30°C; relative humidity = 0.20%; mass vapor = 0.0805 Kg / h; mass fraction = 0.3077 g / Kg. Detected values of the second process gas at the inlet of the second container (point 2-2): temperature = 170°C; flow = 251 m3 / h; dewpoint = -30°C; relative humidity = 0.01%; mass vapor = 0.0607 Kg / h; mass fraction = 0.3041 g / Kg. Detected values of the second process gas at the outlet of the second container (point 2-3): temperature = 115.0°C; flow = 251 m3 / h; dewpoint = -5.00°C; relative humidity = 0.25%; mass vapor = 0.5863 Kg / h; mass fraction = 2.5750 g / Kg. Detected values of the second process gas at the inlet of the second bypass line (point 2-4): are the same detected values at the outlet of the second container (point 2-3). Detected values of the second process gas mixed with the first process gas at the outlet of the first bypass line (point 2-5): temperature = 101.0°C; flow = 251 m3 / h; dewpoint = -0.62°C; relative humidity = 0.55%; mass vapor = 0.8442 Kg / h; mass fraction = 3.5762 g / Kg.

[0087] Bypass. Detected values of the first process gas in the first bypass line (point 1- 6): temperature = 45°C; flow = 50 m3 / h; dewpoint = 10°C; relative humidity = 12.82%; mass vapor = 0.4185 Kg / h; mass fraction = 7.5750 g / Kg. Detected values of the second process gas in the second bypass line (point 2-6): temperature = 115°C; flow = 50 m3 / h; dewpoint = -5°C; relative humidity = 0.25%; mass vapor = 0.1169 Kg / h; mass fraction = 2.5750 g / Kg.

[0088] A capacity of the first process gas to remove humidity has been evaluated by calculating, on the basis of a mass balance, the following two parameters: the first parameter is the mass of water that the first process gas has removed from the incoherent plastics in the first container in relation to the mass of the first process gas, calculated as equal to 1.1983 g / Kg; the second parameter is the mass of water that the first process gas has removed from the incoherent plastics in the first container in the unit of time, calculated as equal to 0.5712 Kg / h.

[0089] It is observed that the temperature of the first process gas exiting the first container (drying hopper) is relatively low and that mixing this first process gas of the first stage with the second process gas removed from the second gas circuit of the second stage by a bypass flow (in this specific embodiment equal to 50 m3 / h) entails an increase in the temperature of the first process gas. In the specific embodiment the temperature of the first process gas passes from 45°C before mixing with the bypass flow to 61.3°C after mixing. Recovery of a part of the heat of the second process stage (dehumidifying stage) to the benefit of the first process stage (drying stage) is thus observed.

[0090] It is further noted that the dewpoint of the first process gas exiting the first container (drying hopper) is relatively high before mixing with the bypass flow (in this specific embodiment equal to 10°C) and that mixing with the bypass flow (in this specific embodiment equal to 50 m3 / h) entails a decrease in the dewpoint at the inlet of the first container (in this specific embodiment, from 10°C to 7.56°C), with a resulting improvement in the quality of the first process gas, i.e. of the ability of the first process gas to remove humidity present in the processed incoherent plastics in the first stage.

[0091] It is also observed that in the second gas circuit of the second process stage (dehumidifying stage) the first, relatively less hot (in this specific embodiment, at 45°C), coming from the first process stage (drying stage) process gas mixes with the second relatively hotter process gas (in this specific embodiment, at 115°C), exiting the second container of the second process stage. This entails a lowering of the temperature (in this specific embodiment, to 87.1°C) of the second process gas at the inlet of the secondcontainer.

[0092] This phenomenon is advantageous because it promotes maintenance of a desired condition at the inlet of the adsorption separating means (molecular sieves), i.e. not exceeding a given temperature threshold in order to ensure effective performance in the adsorption separation of the humidity.

[0093] It is further observed that the first relatively more humid process gas, (dewpoint equal to 10°C), which is bypassed from the first process stage to the second process stage and is mixed with the second relatively less humid process gas, before mixing (dewpoint equal to -5°C), has overall a much reduced negative impact in terms of dehumidifying power of the second process gas (which in this example passes to a dewpoint equal to -0.62°C after mixing, i.e. with a relatively reduced increase).Example 3

[0094] The simulation was run with a flowrate of 100 kg / h of polymer granule with the following process conditions. The bypass flow was increased from 50 to 100 m3 / h compared with example 2.

[0095] Stage 1. Detected values of the first process gas at the inlet of the first heater (point 1-1): temperature = 77.7°C; flow = 214 m3 / h; dewpoint = 4.69°C; relative humidity = 1.98%; mass vapor = 1.1292 Kg / h; mass fraction = 5.2490 g / Kg. Detected values of the first process gas at the inlet of the first container (point 1-2): temperature = 120°C; flow = 214 m3 / h; dewpoint = 4.69°C; relative humidity = 0.42%; mass vapor = 1.0029 Kg / h; mass fraction = 5.2252 g / Kg. Detected values of the first process gas at the outlet of the first container (point 1-3): temperature = 45.0°C; flow = 214 m3 / h; dewpoint = 10.00°C; relative humidity = 12.82%; mass vapor = 1.7943 Kg / h; mass fraction = 7.5750 g / Kg. Detected values of the first process gas at the inlet of the first bypass line (point 1-4): they are the same detected values at the outlet of the first container (point 1-3). Detected values of the first process gas mixed with the second process gas at the outlet of the second bypass line (point 1-5): temperature = 77.7°C; flow = 214 m3 / h; dewpoint = 4.69°C; relative humidity = 1.98%; mass vapor = 1.1292 Kg / h; mass fraction = 5.2490 g / Kg.

[0096] Bypass. Detected values of the first process gas in the first bypass line (point 1- 6): temperature = 45°C; flow = 100 m3 / h; dewpoint = 10°C; relative humidity = 12.82%; mass vapor = 1.7943 Kg / h; mass fraction = 7.5750 g / Kg. Detected values of the second process gas in the second bypass line (point 2-6): temperature = 115°C; flow = 100 m3 / h; dewpoint = -5°C; relative humidity = 0.25%; mass vapor = 0.2339 Kg / h; mass fraction = 2.5750 g / Kg.

[0097] A capacity of the first process gas to remove humidity has been evaluated by calculating, on the basis of a mass balance, the following two parameters: the first parameter is the mass of water that the first process gas has removed from the incoherent plastics in the first container in relation to the mass of the first process gas, calculated as equal to 2.3498 g / Kg; the second parameter is the mass of water that the first process gas has removed from the incoherent plastics in the first container in the unit of time, calculated as equal to 0.7914 Kg / h.

[0098] It is observed that an increase in the value of the bypass flow, i.e. of the flowrate of mixing air between the two stages, consequently, entails an improvement in the conditions of the first process gas at the inlet of the first heater, in particular there is an increase in the temperature and a decrease in the dewpoint. Moving from example 2 to example 3, it is noted that by doubling the bypass flow from 50 to 100 m3 / h, the temperature of the first process gas, after it has been mixed with the second process gas coming from the bypass, passes from 61.3°C to 77.7°C, whereas the dewpoint passes from 7.56°C to 4.69°C.

[0099] It is thus possible to manage the first process stage (drying stage) by a control of the bypass flow in function of the humidity detected in the incoherent plastics processed in the first stage, i.e. the material exiting the first container.

[0100] In practice, if the humidity detected in the incoherent plastics processed in the first stage is too high (for example, greater than a set threshold value), the controller automatically increases the bypass flow to increase the efficacy of the first stage. On the other hand, if the humidity is too low (for example, below a set threshold value), the controller may automatically decrease the bypass flow to reduce the efficacy of the first stage.

[0101] It is noted that the bypass flow, i.e. the mixing flowrate between the two stages, does not necessarily depend on the flowrate of the process gas that flows into the gas circuit of each process stage.

[0102] In particular, it is possible for the bypass flow to be varied, driving the actuating bypass means, whereas both the flowrate of the first actuator that controls the flow of the process gas in the first process stage, and the flowrate of the second actuator that controls the flow of the process gas in the second process stage, may remain constant.

[0103] It is noted that the bypass flow that goes from the second stage to the first stage is the same as and opposite the bypass flow that goes from the first stage to the second stage.

[0104] The bypass flow may be so controlled that the heat exchange between the first process stage and the second process stage is high (thus increasing the bypass flow to increase the heat exchange) but also paying attention that the temperature of the second process gas downstream of the bypass (at point 2-5) does not exceed a preset value.

[0105] It is possible to provide cooling means (not shown, for example air / water exchange means) configured to cool the second process gas downstream of the bypass (in particular in point 2-5) so as to ensure that the temperature of the second process gas at the inlet of the adsorption separating means 11 does not exceed a preset value.

[0106] The bypass flow may be controlled in function of a dewpoint value of the first process gas in order to increase the action of dehumidifying the first stage but also paying attention not to arrive at anticipated saturation of the adsorption separating means 11.

[0107] This double objective may be reached by progressively increasing the bypass flow, so as to decrease the dewpoint value of the gas to point 1-5 (at the inlet of the first container 2) but without exceeding a preset dewpoint value at point 2-5, so that the bypass flow is no longer increased when the dewpoint at the inlet of the adsorption separating means 11 reaches the aforesaid preset value. In practice, the control tries to improve the dewpoint in the first stage without however aggravating the dewpoint in the second stage beyond a certain limit.

[0108] The bypass flow may be controlled, in particular, both in function of at least one temperature of the gas both in function of at least one dewpoint value of the gas. In this case, the control sets the simultaneous fulfilment of two conditions: the temperature T of the gas and the dewpoint DP of the gas at the inlet of the adsorption separating means 11 (at point 2-5) must not exceed two limit values Tlim and DPlim.

[0109] The bypass flow affects the heating of the incoherent plastics in the first stage. In general, the greater the bypass flow the greater will be the heat that enters the first container 2, so that the first stage could do without the first heater 12, or not activate the first heater 12, and use the hot air coming from the second stage.

[0110] The bypass flow also affects the degree of humidity of the second process gas that enters the adsorption separating means 11, because of the humidity coming from the first stage through the bypass flow.

[0111] The control may be set, in particular, so that the humidity content (in practice, the dewpoint value) of the second process gas that enters the adsorption separating means 11 is maintained at a set constant value (setpoint value of the control of the bypass flow) or anyway not beyond a threshold value.

[0112] In one embodiment (not shown), the second process stage may comprise, in particular, injecting means configured to inject into the second gas circuit and auxiliary gas (nitrogen and / or air) with a relatively low humidity content, for example an auxiliary gas with a dewpoint value below -15°C, or below -20°C, or below -25°C, or comprised between -15°C and -80°C. The auxiliary gas may be processed, before being injected, to decrease the humidity content thereof. The auxiliary gas may be dehumidified by a process comprising a step of compressing the auxiliary gas followed by a step of expanding the auxiliary gas.

[0113] The auxiliary gas may be injected into point 2-5 of the second gas circuit 5. The auxiliary gas may be injected before the second actuating means 7. The auxiliary gas may be injected into a vacuum point of the second gas circuit 5. The auxiliary gas may be injected into the point of the second gas circuit 5 downstream of the bypass means.

[0114] The flowrate of the auxiliary gas that is added to the flow of the second gas circuit 5 may be compensated by the gas leaks inside the system, which in general is not a hermetically sealed system. It should be remembered, for example, that each time the incoherent plastics is loaded into the hopper (second container 3) there is a communication between the inside of the hopper and the outer environment, with the resulting possibility of fluid leaks to the exterior.

[0115] The injection flow of the auxiliary gas may be controlled, in particular, on the basis of a humidity value detected in the second gas circuit 5, in particular in point 2-5. This humidity value may be, for example, a dewpoint value detected by a dewpoint sensor (arranged in point 2-5).

[0116] In one embodiment, it is possible to preset a limit value DPL of the dewpoint (for example, DPL = -5°C). If the detected dewpoint value DPR in a preset point of the second gas circuit 5 is less than the limit value DPL (for example, DPR = -10°C), then the control does not activate any injection flow of the (dehumidified) auxiliary gas. If the detected dewpoint value DPR in the second gas circuit 5 rises beyond the limit value (for example, DPR = -3 °C), then the control activates the injection flow of the auxiliary gas. The amount of flow may be, for example, a constant preset value (substantially a control of ON-OFF type) that is maintained for a set period of time or until the detected dewpoint value DPR in the second gas circuit 5 again falls below the limit value DPL. A more elaborate control is nevertheless possible (for example a control of PID type) of the injection flow in function of the detected dewpoint value DPR.

[0117] Injecting the (dehumidified) auxiliary gas may be used, in particular, to protectthe adsorption separating means 11, preventing saturation thereof. Further, injecting the auxiliary gas permits an appropriate, rapid and effective control of the dehumidification treatment in the second process stage.

[0118] The injection gas may comprise, in particular, compressed air that may be treated before being injected, for example filtered to reduce the quantity of contaminants thereof. In particular it is possible to pre-treat the compressed air to be injected so that it does not exceed a given concentration of particulate and / or a given dewpoint value and / or a given concentration of oil.

Claims

CLAIMS1. Apparatus for processing incoherent plastics, comprising: a first container (2) configured to contain incoherent plastics and a second container (3) configured to receive incoherent plastics coming out of said first container (2); a first gas circuit (4) to feed a first process gas to a gas inlet of said first container (2) and to withdraw used gas from a gas outlet of said first container (2) and a second gas circuit (5) to feed a second process gas to a gas inlet of said second container (3) and to withdraw used gas from a gas outlet of said second container (3); first actuator means (6) configured to control a gas flow in said first gas circuit (4) and second actuator means (7) configured to control a gas flow in said second gas circuit (5); bypass means configured to simultaneously generate a first bypass flow from said first gas circuit (4) to said second gas circuit (5) and a second bypass flow from said second gas circuit (5) to said first gas circuit (4).

2. Apparatus according to claim 1, wherein said bypass means comprises at least two bypass lines (8; 9) each of which extends between said first gas circuit (4) and said second gas circuit (5).

3. Apparatus according to claim 2, wherein said two bypass lines comprise a first bypass line (8) which extends between a first point of said first gas circuit (4) and a first point of said second gas circuit (5) and a second bypass line (9) which extends between a second point of said first gas circuit (4) and a second point of said second gas circuit (5), said first point of said first gas circuit (4) being arranged between said gas outlet of said first container (2) and said second point of said first gas circuit (4), said second point of said second gas circuit (5) being arranged between said gas outlet of said second container (3) and said first point of said second gas circuit (5).

4. Apparatus according to claim 3, wherein said first actuator means (6) comprises a first actuator arranged in said first gas circuit (4) between said gas inlet of said first container (2) and said first point of said first gas circuit (4) and / or between said gas inlet of said first container (2) and said second point of said first gas circuit (4).

5. Apparatus according to claim 3 or 4, wherein said second actuator means (7) comprises a second actuator arranged in said second gas circuit (5) between said gas inlet of said second container (3) and said first point of said second circuit gas (5)and / or between said gas inlet of said second container (3) and said second point of said second gas circuit (5).

6. Apparatus according to any one of the preceding claims, wherein said bypass means comprises bypass actuator means (10) configured to control said first bypass flow and / or said second bypass flow.

7. Apparatus according to claim 6, wherein said bypass actuator means (10) comprises one or more flow control servo valves.

8. Apparatus according to claim 7, wherein said one or more flow control servo valves comprise a servo valve in a first bypass line (8) and / or a servo valve in a second bypass line (9).

9. Apparatus according to claim 7 or 8, wherein said one or more flow control servo valves comprise a servo valve in the first gas circuit (4) between a first bypass line (8) and a second bypass line (9) and / or a servo valve in the second gas circuit (5) between a first bypass line (8) and a second bypass line (9).

10. Apparatus according to any one of the preceding claims, comprising control means configured to feedback control said first bypass flow and / or said second bypass flow based on at least one chemical-physical characteristic of the incoherent plastics coming out of said first container (4).

11. Apparatus according to claim 10, wherein said at least one chemical-physical characteristic includes a moisture content detected in the incoherent plastics coming out of said first container (4).

12. Apparatus according to any one of the preceding claims, comprising control means configured to feedback control said first bypass flow and / or said second bypass flow based on at least one chemical-physical characteristic detected in the gas in said first gas circuit (4).

13. Apparatus according to any one of the preceding claims, comprising control means configured to feedback control said first bypass flow and / or said second bypass flow based on at least one chemi cal -physical characteristic detected in the gas in said second gas circuit (5).

14. Apparatus according to any one of the preceding claims, comprising control means configured to feedback control said first bypass flow and / or said second bypass flow based on at least one chemi cal -physical characteristic detected in the gas in at least one bypass line (8; 9) of said bypass means.

15. Apparatus according to any one of the preceding claims, wherein said first gas circuit(4) is a closed circuit and / or wherein said second gas circuit (5) is a closed circuit.

16. Apparatus according to any one of the preceding claims, wherein said second gas circuit (5) comprises adsorption separator means (11) configured to separate at least one substance, in particular water, from the second process gas; said apparatus comprising, in particular, control means configured to feedback control said first bypass flow and / or said second bypass flow based on at least one chemical-physical characteristic, in particular a characteristic indicative of a moisture content, detected in the gas in said second gas circuit (5) upstream of said adsorption separator means (H).

17. Apparatus according to any one of the preceding claims, wherein said first gas circuit(4) comprises a first heater (12) of the first process gas and / or wherein said second gas circuit (5) comprises a second heater (13) of the second process gas.

18. Apparatus according to any one of the preceding claims, comprising injection means configured to inject an auxiliary flow of an auxiliary gas into said second gas circuit(5); said apparatus comprising, in particular, control means configured to control said auxiliary flow based on a moisture content detected in said second gas circuit (5).

19. Apparatus according to claim 18, wherein said auxiliary flow is injected into said second gas circuit (5) downstream of said bypass means.

20. Method for processing incoherent plastics, said method comprising: introducing incoherent plastics into a first container (2); extracting incoherent plastics from said first container (2) and introducing it into a second container (3); feeding a first process gas to a gas inlet of said first container (2) and withdrawing used gas from a gas outlet of said first container (2); feeding a second process gas to a gas inlet of said second container (3) and withdrawing used gas from a gas outlet of said second container (3); simultaneously generating a first bypass flow from a first gas circuit (4) in which said first process gas flows to a second gas circuit (5) in which said second process gas flows and a second bypass flow from said second gas circuit (5) to said first gas circuit (4).

21. Method according to claim 20, comprising feedback controlling said first bypass flow and / or said second bypass flow based on at least one chemi cal -physical characteristic detected in the incoherent plastics exiting from said first container (2); said at least one chemical-physical characteristic including, in particular, the dewpoint or other characteristic indicative of a moisture content in the incoherent plastics.

22. Method according to claim 20 or 21, comprising feedback controlling said first and second bypass flows based on at least one chemical-physical characteristic detected in the gas in said first gas circuit (4) and / or based on at least one characteristic chemical-physical characteristic detected in the gas in said second gas circuit (5) and / or on the basis of at least one chemical-physical characteristic detected in the gas in at least one bypass line (8; 9) between said first and second gas circuits (4; 5).

23. Method according to any one of claims 20 to 22, comprising heating said first process gas and / or heating said second process gas.

24. Method according to any one of claims 20 to 23, comprising separating at least one substance, in particular water, from said second process gas by means of adsorption separator means (11).

25. Method according to claim 24, comprising feedback controlling said first and second bypass flows based on at least one chemical-physical characteristic detected in the gas in said second gas circuit (5) before said adsorption separator means (11); said at least one chemical-physical characteristic including, in particular, the dewpoint or other characteristic indicative of a moisture content in the gas in said second gas circuit (5).

26. Method according to any one of claims 20 to 25, comprising injecting an auxiliary gas into said second gas circuit (5), said auxiliary gas having a dewpoint value lower than -15°C.

27. Method according to claim 26, comprising dehumidifying said auxiliary gas before being injected, in particular by a compression of the auxiliary gas followed by an expansion of the auxiliary gas.

28. Method according to claim 26 or 27, comprising controlling said auxiliary flow based on a detected moisture value (DPR) in said second gas circuit (5); being provided, in particular, to activate or increase said auxiliary flow if a moisture content detected in said second gas circuit (5) increases and / or to stop or decrease said auxiliary flow if moisture content detected in said second gas circuit (5) decreases.

Images