METHOD AND PLANT FOR THE PROCESSING OF WASTE

Abstract

A plant for the processing of waste includes an outer housing and a grinding cell, in which a grinding chamber is defined having at least one inlet opening for introducing the waste to be processed, and at least one outlet opening for discharging the material resulting from waste processing. The openings are associated with a corresponding closure element, adapted to isolate the grinding chamber from the outer environment. The outer housing defines therein a space receiving the grinding cell and integrally surrounds the grinding cell, and in which the space is accessible through at least one door.

Claims

1. A plant for the processing of waste, comprising an outer housing (101) and a grinding cell (1b), in which a grinding chamber (1) is defined having at least one inlet opening (102) for introducing the waste to be processed, and at least one outlet opening (103) for discharging material resulting from waste processing, said inlet and outlet openings (102, 103) being associated with a corresponding closure element (1a, 104), that isolates the grinding chamber (1) from an outer environment, wherein said outer housing (101) defines therein a space (105) receiving the grinding cell (1b) and integrally surrounds said grinding cell (1b), and in that said space (105) is accessible through at least one door (110, 111).

2. The plant according to claim 1, wherein the outer housing (101) comprises a support frame (106) and a plurality of panels (107) attached to the frame (106) and defining walls of said space (105) in which the grinding cell (1b) is received, and wherein at least one of said panels (107) comprises the at least one door (110,111) which is openable.

3. The plant according to claim 2, wherein the outer housing (101) defines therein a collection chamber (108) for the material discharged from the grinding cell (1b), said collection chamber (108) being in communication with the grinding chamber (1) defined within the grinding cell (1b) through a duct (109).

4. The plant according to claim 3, wherein the grinding chamber (1) houses a rotor (2) provided with at least one radial vane (35a, 35b) provided, at its end (37a, 37b) distal relative to a rotation axis (“S”), with a hammerhead (39) in which two opposite impact surfaces (41, 43) are defined, said impact surfaces operating when the rotor rotates clockwise or counter-clockwise, respectively, a first one (41) of the impact surfaces being flat and perpendicular to an angular direction of rotation of the vane, and the other impact surface (43) being variously inclined.

5. The plant according to claim 4, wherein the grinding cell (1b) is equipped with at least three temperature sensors (20) arranged along corresponding generatrices of the grinding chamber (1) of the grinding cell (1b) angularly spaced from one another by about 120°, at different heights, namely at different heights relative to the base (1c) of the grinding cell (1b), in corresponding radial bores provided in a grinding cell wall, said sensors (20) being adapted to generate a corresponding signal indicative of the temperature measured inside the grinding cell.

6. A method for the processing of waste, comprising the steps of: providing a plant according to claim 1, opening the closure element (1a) closing the inlet opening (102) of the grinding cell; opening the door (110) in order to access the space (105) in which the grinding cell (1b) is housed; loading the grinding cell (1b) with a certain amount of waste; closing the inlet opening (102) of the grinding cell (1b) by means of the corresponding closure element (1a); closing the door (110) for isolating the space (105) receiving the grinding cell (1b) from the outer environment; and starting a grinding step.

7. The method according to claim 6, wherein a piped effluent exiting the grinding cell (1b) during the processing of said waste is processed by a vertically extending multi-stage separation unit (4), said unit comprising a first cyclone separator stage (4a), adapted to remove larger particles.

8. The method according to claim 7, wherein the grinding step comprises: a first step in which a rotor (2) is rotated in a first, clockwise or counter-clockwise direction for operating with a first wedge-shaped impact surface (43) of a vane (35a, 35b) associated with the rotor (2); and a second step in which the rotor (2) is rotated in a second, opposite direction for operating with a second, knocker impact surface (41) of a vane (35a, 35b) associated with the rotor (2).

9. The method according to claim 8, wherein in the step of rotation in the first direction, the rotor (2) is driven at a constant speed, and wherein in the second step of rotation in the second, opposite direction, the rotor (2) is driven at a constant torque.

10. The method according to claim 9, wherein a step is provided of generating, inside the housing (101), an upward air flow passing through said space (105) and brushing a lateral wall of the grinding cell (1b).

11. The method according to claim 6, wherein the grinding step comprises: a first step in which a rotor (2) is rotated in a first, clockwise or counter-clockwise direction for operating with a first wedge-shaped impact surface (43) of a vane (35a, 35b) associated with the rotor (2); and a second step in which the rotor (2) is rotated in a second, opposite direction for operating with a second, knocker impact surface (41) of a vane (35a, 35b) associated with the rotor (2).

12. The method according to claim 11, wherein in the step of rotation in the first direction, the rotor (2) is driven at a constant speed, and wherein in the second step of rotation in the second, opposite direction, the rotor (2) is driven at a constant torque.

13. The method according to claim 6, wherein a step is provided of generating, inside the housing (101), an upward air flow passing through said space (105) and brushing a lateral wall of the grinding cell (1b).

14. The plant according to claim 1, wherein the outer housing (101) defines therein a collection chamber (108) for the material discharged from the grinding cell (1b), said collection chamber (108) being in communication with the grinding chamber (1) defined within the cell (1b) through a duct (109).

15. The plant according to claim 2, wherein the grinding chamber (1) houses a rotor (2) provided with at least one radial vane (35a, 35b) provided, at its end (37a, 37b) distal relative to a rotation axis (“S”), with a hammerhead (39) in which two opposite impact surfaces (41,43) are defined, said impact surfaces operating when the rotor rotates clockwise or counter-clockwise, respectively, a first one (41) of the impact surfaces being flat and perpendicular to an angular direction of rotation of the vane, and the other impact surface (43) being variously inclined.

16. The plant according to claim 1, wherein the grinding chamber (1) houses a rotor (2) provided with at least one radial vane (35a, 35b) provided, at its end (37a, 37b) distal relative to a rotation axis (“S”), with a hammerhead (39) in which two opposite impact surfaces (41,43) are defined, said impact surfaces operating when the rotor rotates clockwise or counter-clockwise, respectively, a first one (41) of the impact surfaces being flat and perpendicular to an angular direction of rotation of the vane, and the other impact surface (43) being variously inclined.

17. The plant according to claim 1, wherein the grinding cell (1b) is equipped with at least three temperature sensors (20) arranged along corresponding generatrices of the grinding chamber (1) of the grinding cell (1b) angularly spaced from one another by about 120°, at different heights, namely at different heights relative to the base (1c) of the grinding cell (1b), in corresponding radial bores provided in a grinding cell wall, said sensors (20) being adapted to generate a corresponding signal indicative of the temperature measured inside the grinding cell.

Description

SYNTHETIC DESCRIPTION OF THE FIGURES

[0079] Some preferred embodiments of the invention will be described below by way of non-limiting example with reference to the accompanying figures in which:

[0080] FIG. 1 is a simplified block diagram of a plant made in accordance with a preferred embodiment of the invention;

[0081] FIG. 2 is a perspective view from above of a pair of vanes in accordance with a preferred embodiment of the invention;

[0082] FIG. 3 is a front-plan schematic view of the plant according to a preferred embodiment of the invention;

[0083] FIGS. 4A to 4D are perspective views of the plant of FIG. 3, in as many operating steps.

[0084] The same references were used in all the figures to distinguish equal or functionally equivalent components.

DESCRIPTION OF SOME PREFERRED EMBODIMENTS OF THE INVENTION

[0085] With reference to FIG. 1, a functional block diagram of the plant object of the present invention is shown in a preferred embodiment. Reference 1 indicates a processing chamber obtained inside a monolithic cell or drum 1b provided above with a lid 1a. Inside the chamber 1, near the lower base 1c, a rotor 2 is provided driven by an electric motor 3 located outside the drum 1b. The transmission of motion from the motor 3 to the rotor 2 takes place through a shaft 3a passing through the lower base 1c of the drum 1b at a hole provided therein. Reference 2a indicates the discharge duct of the processed waste, which will be mostly in the solid and dried state.

[0086] Two series are provided inside the processing chamber 1, each comprising three temperature sensors 20 (two of which are visible in the figure), oriented angularly at about 120° and preferably positioned at different heights for detecting the temperature in the processing chamber 1 in order to control the operation of the plant and avoid overheating. The second series of sensors is advantageously provided to arrange backup sensors in the event of failure of one or more sensors of the first series.

[0087] A vertically extending multi-stage separation unit, to which the gaseous effluent from the processing chamber 1 arrives through the duct 17 and by means of a liquid-ring vacuum pump 5, is indicated with reference 4.

[0088] The multi-stage separation unit 4 comprises a first lower cyclone stage 4a, a second intermediate column stage 4b with Raschig ring filling, and a third upper water scrubber stage 4c.

[0089] A dryer filter, to which the gas and vapour flow discharged above the multi-stage separation unit 4 arrives, is indicated with reference 6. Downstream of the filter 6, a de-saturator filter 7 is provided and downstream of the de-saturator filter 7 an absolute HEPA filter 8 and subsequently an activated-carbon HEGA filter 9 are provided. A suction unit indicated with reference 10 is located downstream of the activated-carbon filter 9 and is adapted to generate the air flow sucked by the multi-stage separation unit 4. The filter 6, the desaturator 7, the HEPA filter 8 and the activated-carbon HEGA filter 9 collectively define a volatile effluent processing unit 15 from which the purified gaseous effluent 17a is discharged, preferably released into the environment as it is harmless.

[0090] A steam generator, which communicates with the processing chamber 1 through a duct 22, is indicated with reference 11. The purpose of the steam generator is to restore the necessary humidity inside the processing chamber 1.

[0091] At the base of the multi-stage separation unit 4 there is a duct 18 for extracting, thanks to a recirculation pump 12, condensate and scrubbing fluid that reaches the base of the separation unit 4. The duct 18 communicates with a filter 13 placed upstream of a heat exchanger 14 and feeds the liquid ring pump 5 and the scrubber 4c. A valve 18a for regulating the flow is provided to intercept the recirculation fluid directed to the pump 5 and provided for the eventual reintegration of the liquid ring, necessary for the regular operation of said pump 5. Reference 19 indicates a discharge or “blow down” circuit communicating with the duct 18 through valves 12a, 12b, for the discharge of the excess liquid from the duct 18.

[0092] Reference 20 indicates the cooling circuit fed with cooling fluid consisting, for example, of seawater and provided with a refrigeration unit or chiller 16. The cooling circuit 20 is primarily dedicated to cooling the recirculation fluid in the exchanger 14, cooling the motor 3 that drives the rotor 2, and maintaining the operating temperature of the cold operating de-saturator filter 7. Reference 21 indicates the return circuit of the cooling fluid and reference 23 indicates the circuit for supplying the replenishment fluid of the plant, for example fresh water for replenishment, into the chamber 1 and the multi-stage separation unit 4, by means of corresponding shut-off valves 23a and 23b.

[0093] With reference to FIG. 2, the rotor 2 associated with the processing chamber 1 of the grinder is illustrated in detail.

[0094] The rotor 2 comprises a central body 33 defining at least one radial vane 35a,35b provided, at its end 37a,37b distal relative to the rotation axis “S” of the rotor 2, with a hammerhead 39. In the example shown, a first, knocker impact surface 41, adapted to operate when the rotor 2 rotates in a first, clockwise direction and a second, wedge-shaped impact surface 43, adapted to operate when the rotor 2 rotates in a second direction opposite to the first, counter-clockwise in the example shown, are defined in the hammerhead 39.

[0095] The first, knocker impact surface 41 extends on a single plane 41a substantially parallel to the rotation axis “S” of the rotor 2. Furthermore, in the example shown, the plane 41a on which the knocker impact surface 41 extends is substantially perpendicular to the angular direction of rotation of the rotor 2. More precisely, in the embodiment shown, said plane is furthermore tangent to an imaginary cylinder with its axis coinciding with the rotation axis “S” of the rotor 2 and preferably contained in the body of the rotor 2, i.e., with the generatrices of said imaginary cylinder intercepting the body of the rotor 2.

[0096] The second, wedge-shaped impact surface 43 extends on a pair of planes 43a,43b inclined relative to the plane of rotation of the rotor 2 perpendicular to the rotation axis “S”. In addition, the planes 43a,43b are inclined relative to each other.

[0097] Said two planes 43a,43b on which the second surface 43 extends are inclined at a corresponding angle between 15° and 90°, preferably about 30° with respect to the plane of rotation. Moreover, said two planes 43a,43b on which the second surface 43 extends are inclined at an angle β between 90° and 180°, preferably about 120°, relative to each other.

[0098] Advantageously, according to a preferred embodiment of the invention, the rotor 2 is rotated counter-clockwise to make the wedge-shaped impact surfaces 43 work to shred the waste received in the chamber 1, and in the opposite direction to increase the temperature and fluidize the waste by impacting the knocker impact surfaces 41 and the sliding of the material against the walls of the chamber 1. Inside the chamber 1, radial buffers (not shown) can optionally be provided which cooperate with the knocker impact surfaces 41 to increase the temperature raising effect.

[0099] According to a preferred embodiment of the invention, in the step in which the surfaces 43 operate, the impeller speed is preferably kept constant. Still according to the invention, in the step in which the knocker impact surfaces 41 operate, it is instead preferably varied according to the torque estimated by measuring the current absorbed by the motor 3. Advantageously, the speed variation as a function of the torque allows to avoid triggering the floating of the fluidized mass of waste that would escape the action of the rotor 2 as it will be pushed to the surface in the processing chamber 1. The speed variation is preferably carried out so as to maintain the torque substantially constant.

[0100] Referring to FIG. 3, a plant 100 made in accordance with a preferred embodiment of the invention is shown schematically.

[0101] In FIG. 3 reference 101 indicates the outer housing of the plant 100 and reference 1b indicates a grinding cell in which a grinding chamber 1 is defined. The chamber 1 is provided with an inlet opening or mouth 102, for introducing the waste to be processed, and at least one outlet opening or mouth 103, for discharging the material resulting from the waste processing. The openings 102 and 103 are provided with a corresponding closure element 1a and 104, adapted to isolate the grinding chamber 1 from the outer environment. In the embodiment shown, the closure element 1a comprises a lid hinged to the wall of the cell 1b and driven by an actuator. The closure element 104 comprises a bulkhead, movable radially with respect to the cylindrical body of the cell 1b and actuated by an actuator. The actuators of the lid 1b and bulkhead 104 may, for example, be of an electrical or pneumatic type and controlled by an electronic unit responsible for coordinating the functions of the plant 100. The outer housing 101 defines therein a space 105 in which the cell 1b is received and which integrally surrounds said cell.

[0102] The outer housing 101 comprises, in the embodiment shown, a support frame 106 and a plurality of panels 107 attached to the frame 106 and defining the walls of said space 105 in which the grinding cell 1b is received.

[0103] The outer housing 101 further defines therein a collection chamber 108 for the material discharged from the grinding cell 1b. The collection chamber 108 is in communication with the grinding chamber 1 defined within the cell 1b, through a duct 109.

[0104] The grinding chamber 1 houses a rotor 2 provided with a pair of radial vanes 35a,35b equipped, at their ends distal relative to the rotation axis, with a hammerhead in which two opposite impact surfaces 41,43 are defined, said impact surfaces operating, respectively, when the rotor 2 rotates clockwise or counter-clockwise.

[0105] Referring to FIG. 4A, the path of the washing air flow induced by the suction unit 10 and corresponding to a first operation mode of the plant 100 is schematically shown, which path of the washing air flow is aimed at extracting heat from the processing chamber 1 provided in the cell 1b, to avoid the excessive increase of the temperature in said cell 1b during the operation of the grinder, i.e., when the lid 1b is closed. The air sucked by the suction unit 10 at the top of the plant 100 enters the housing 101 through dedicated openings provided at the base of the housing 101 (arrows 200), crosses the space 105 defined inside the housing 101, brushing the surfaces that the air flow encounters during transit and subtracting heat (arrows 201). The air flow sucked by the suction unit 10 is filtered by the air treatment unit 15 and is finally released into the outer environment surrounding the plant 100 (arrow 202).

[0106] In this operation mode, the door 110 that closes the space 105 and the door 111 that closes the collection chamber 108 are closed so that the air sucked by the suction unit 10 substantially enters only the base of the housing 101.

[0107] Referring to FIG. 4B, the path of the washing air flow induced by the suction unit 10 and corresponding to a second operation mode of the plant 100 and aimed at removing the powder that is created inside the loading section of the space 105 when the lid 1a of the processing chamber 1 is opened at the end of the waste processing is schematically shown. The air flow path is substantially the same as in the first described mode.

[0108] Referring to FIG. 4C, the path of the washing air flow induced by the suction unit 10 and corresponding to a third operation mode of the plant 100 and aimed at sucking air from the loading section of the space 105 during the loading of waste when the door 110 for access to said loading section of the space 105 is open and the lid 1a of the cell 1b is also open is schematically shown.

[0109] The air sucked by the suction unit 10 placed at the top of the plant 100 enters the housing 101 through the front opening created when the door 110 is open (arrows 210), crosses the space 105 defined inside the housing 101, brushing the surfaces that the air flow encounters during transit and consequently subtracting the dust and other volatile substances (arrows 211) and blocking the exit towards the front part of the plant. The air flow sucked by the suction unit 10 is filtered by the air treatment unit 15 and is finally released into the outer environment surrounding the plant 100 (arrow 212).

[0110] Referring to FIG. 4D, the path of the washing air flow induced by the suction unit 10 and corresponding to a fourth operation mode of the plant 100 and aimed at sucking air from the discharge section of the space 105 in which the collection chamber 108 is defined during the discharge of the waste when the access door 111 to said collection chamber 108 is open is schematically shown. In this mode, the air sucked by the suction unit 10 enters from the access opening to the discharge section of the space at a speed suitable to prevent dust and volatile components exiting from said discharge section (arrows 220). The sucked air flow passes through the discharge section of the space 105, the communication duct 109 with the processing chamber 1, the discharge outlet 103, the processing chamber 1 and exits into the loading section of the space 105 through the opening or loading mouth 102 provided to access the processing chamber 1. The air flow flowing outside the processing chamber 1 (arrow 221) is subsequently filtered in the same manner as in the previous modes and discharged outside the housing 101 (arrow 222).

[0111] Advantageously, the latter two operation modes are provided in particular for protecting the operator and the environment surrounding the plant, from the pollution of volatile substances that could exit from the plant during the loading and discharge operations, respectively.

INDUSTRIAL APPLICABILITY

[0112] The plant according to the invention is capable of operating with a wide range of waste flows, in particular of the type produced on board boats, ranging from undifferentiated waste to separate recyclable materials.