WO2015086939A1

WO2015086939A1 - Method for regulating the ventilation of a pre-composting drum

Info

Publication number: WO2015086939A1
Application number: PCT/FR2014/052978
Authority: WO
Inventors: Boris EFREMENKO; Serge Gamache; Loïc LOILLIER; Christian THOMIN
Original assignee: Veolia Proprete
Priority date: 2013-12-12
Filing date: 2014-11-20
Publication date: 2015-06-18
Also published as: FR3014867B1; FR3014867A1

Abstract

The invention concerns a method for regulating the ventilation of a pre-composting drum (10), into which waste (19) is introduced (100) and of which the shutters are closed (101). It is essentially characterised in that it comprises: - characterising (102) beforehand the nature of the waste introduced, - measuring (103) the temperature and determining (104) the total mass of waste (19) in the drum, - calculating (105) at least one of the values chosen from a quantity of air and a flow rate of air to be injected, depending on the temperature measured, from the determined total mass of the waste, and from the characterised nature of the waste, with reference to a set of matches stored in a memory, and - injecting (106) the calculated quantity of air or injecting the air at the calculated flow rate into the drum (10) by means of a fan (17), while the inlet shutter (12) and outlet shutter (13) are closed.

Description

METHOD FOR REGULATING THE VENTILATION OF A DRUM

PRE-COMPOSTING.

The present invention relates to the field of pre-composting, in particular the ventilation of the pre-composting rotary drums also called sequential rotary bioreactors (BRS) or bioreactor-stabilizers and hereinafter called concision drum.

Conventionally, a drum has a generally cylindrical shape. It is configured to be fed with at least partially organic materials, for example household waste or sludge, hereinafter called "waste".

The drum has two ends, a so-called inlet end through which the drum is fed with waste, and a so-called outlet end through which the waste is extracted after a residence time in the drum. In operation, it is rotated about its axis of rotation. A helix or an internal form of helical type at least input (the rest of the tube can be smooth) makes it possible to mechanically advance the waste from the inlet end to the outlet end by the single rotation of the drum.

The axis of rotation of the drum may be horizontal or slightly inclined so as to change the residence time of the waste.

Typically, the length and diameter of the drum are chosen according to the desired residence time of the waste to be treated and the speed of rotation. For example some drums are several tens of meters long (typically 40 meters) and a few meters in diameter (typically 4 meters) for a rotation speed of the order of 0.5 to 1.5 turns per minute. Generally, the feed and the waste extraction are carried out so as to have a filling rate of the drum approximately constant over time. The drum must not be filled completely with the waste in order to leave an oxygenated gas mixture, in this case air, in contact with said waste. The volume of waste is therefore less than the internal volume of the drum, so as to leave a certain amount of oxygen available for the aerobic degradation of the waste.

The drum typically separates the organic fractions from the inorganic fractions of the waste. This separation is also called "pre-treatment" of the waste because it is often prior to a fermentation process (for example a composting) or prior to a process of anaerobic digestion of the organic fractions of said waste.

For this purpose, the drum may be equipped with blades or knives in order to lacerate the plastic bags and may be equipped at its outlet with orifices (typically several centimeters in diameter) or be equipped with a device allowing the granulometric separation of the waste. solid by screening.

Drum pretreatment can also be aimed at accelerating the fermentation of the organic fractions and making the mixture homogeneous. For this purpose, the drum is generally equipped with a device for watering the waste and a device for aerating the waste in the drum to obtain an aerobic fermentation.

At the inlet of the drum, a unit volume of waste is introduced at the inlet end of the drum via an inlet flap according to an inlet flow. The inlet flap is open to allow the introduction of a unit volume of waste in the drum, and then closed after this introduction. At the outlet of the drum, another volume of waste is extracted at the outlet end of the drum via an exit hatch at an output rate, possibly different from the inlet flow rate. The exit hatch is opened to allow the extraction of a unit volume of drum waste, and then closed after this extraction.

Between these two ends, each unit volume of waste introduced into the drum is mixed with the unit volumes introduced previously and remains in the drum for a so-called residence time, generally several days.

Without the introduction and extraction of waste, the ends of the drum are closed by the inlet and outlet hatches, also called valves, which are generally impervious to at least odors.

In fact, the organic matter degrades in the drum by fermentation and generates malodorous volatile molecules (VOCs, mercaptans, H2S, etc.) which generally require a suitable treatment device connected to the drum.

In operation, the drum rotates about its axis of rotation, generally substantially horizontal, for example of the order of a few revolutions / minute. The rotation is usually continuous, at least during the day.

Conventionally, at night, the drum is left rotating but the entrance and exit hatches remain closed. The oxygen supply is then no longer possible. This nocturnal closure responds to two considerations, one economic aiming to avoid employing operators at night to feed the drum with waste and to extract organic fractions; and the other biological aiming to leave the bacteria present in the waste at rest.

However, with a mass of waste enclosed in a sealed drum for several hours, there is a high risk of anaerobic waste fermentation, which affects the quality of the compost and increases the risk of foul odors, making the wastewater treatment systems malodorous volatile molecules complex and expensive.

The opening of the exit hatch or the inlet flap makes it possible to ventilate certain drums, which avoids putting them in overpressure, but such ventilation is not controlled and can only be implemented for waste. that do not generate malodorous volatile molecules.

In this context, the present invention provides a method of ventilating a pre-composting drum.

More specifically, according to a first of its objects, the invention relates to a method of regulating the ventilation of a pre-composting drum comprising an inlet flap and an outlet flap, the method comprising the steps of:

- introduce waste into the drum and

- close the entrance hatch and the exit hatch.

It is essentially characterized in that it further comprises steps of:

- to characterize in advance the nature of the waste introduced,

- measure the temperature of the waste in the drum, - determine the total mass of the waste contained in the drum,

calculate at least one of the values of a quantity of air and a flow of air to be injected, as a function of the measured temperature, of the total mass of the determined waste, and of the nature of the characterized waste, by reference to a set of matches stored in a memory, and

- Inject the calculated amount of air or inject air according to the flow rate calculated in the previous step in the drum by a fan, while the inlet flap and the outlet flap are closed.

In addition, a step of:

extract air from the drum by an extractor.

It can be provided that the extractor is connected to a pipe network in which the pressure is equal to a set pressure, preferably substantially constant, the process comprising the steps of:

- measure the pressure in the pipe network, and

- control the extraction rate of the extractor as a function of the difference between the set pressure and the pressure measured in the pipe network.

It can be expected that at least one of the steps of the air injection and the extraction of air is carried out continuously.

It can be expected that at least one of the steps of the air injection and the extraction of the air is carried out in cycles.

It can be expected that the amount of air injected or extracted in a given cycle also depends on at least one of the values among the amount of air injected in the previous cycle and the amount of air extracted in the previous cycle.

There may be a step of distributing the amount of air calculated between several fans, each fan blowing an amount of air equal to a portion of the calculated amount of air.

One can provide a step of generating an air flow between the fan and the extractor:

in the direction of the scroll of the waste in the drum,

- Or in the opposite direction of the scroll of waste in the drum.

It can be provided that the drum is equipped with gills and a device for selectively closing said gills, the preceding comprising steps consisting of:

- Locate the angular position of said gills, and

- Slaving the selective closure of said gills to the angular position identified.

According to another of its objects, the invention also relates to a computer program comprising program code instructions for implementing the method according to the invention when said program is executed on a computer.

Unlike the prior art where, typically at night, the drum is left in rotation but closed by trapping a certain amount of air, thanks to the invention, it is intended to inject and extract air in a controlled manner, which improves the fermentation day and night, avoiding that the drum is likely to go into anaerobic mode. Other characteristics and advantages of the present invention will emerge more clearly on reading the following description given by way of illustrative and nonlimiting example and with reference to the appended figures in which:

FIG. 1A illustrates an embodiment of a drum according to the invention, seen in longitudinal section,

FIG. 1B illustrates a cross section along the plane A-A of the drum of FIG. 1A,

FIG. 2A illustrates another embodiment of a drum according to the invention, seen in longitudinal section,

FIG. 2B illustrates a cross-section along plane B-B of the drum of FIG. 2A,

FIG. 2C illustrates a cross-section of another embodiment of a drum according to the invention, and

FIG. 3 illustrates an embodiment of the method according to the invention.

Conventionally, a drum 10 comprises a cylindrical main body 11, an inlet flap 12, in this case mounted on a feed chute 14, and an outlet flap 13.

The waste 19 is introduced 100 into the drum 10 through the inlet hatch 12.

Typically, the inlet flap 12 is substantially horizontal if it is mounted in the feed chute 14 or substantially vertical if it is mounted on the drum 10; the outlet hatch 13 is mounted on the drum 10 and substantially vertical. After partial filling of the drum 10, the waste 19 abuts against the outlet hatch 13, so that at the opening of the outlet hatch 13, the waste can be extracted from the drum 10 by gravity. Preferably, the height of the waste in the drum 10 at the outlet hatch 13 is greater than the height of the outlet hatch 13, so that the opening of the hatch does not generate a call for air, and that any air blown at this end by means of ventilation (see the embodiment illustrated in Figure 2 and described below) can not exit through the outlet door 13.

The drum 10 also comprises a cowling 15, mounted in the upper part of said drum 10, that is to say in the upper part of the horizontal plane passing through the axis of rotation of the drum 10, and disposed towards the outlet end, that is between the middle of the drum 10 and the exit end of the drum 10. Preferably, the inner shape of the cowling 15 matches the outer shape of the drum 10. In this case the cowling has an annular internal shape ( Figure 1B).

According to the present solution, the drum 10 further comprises louvers 16. Each lug 16 is a recess, or through-hole, of the main body 11. The louvers 16 are thus integral in rotation with the drum 10. They are arranged towards the end output, preferably in radial symmetry, and vis-à-vis the annular portion of the cowling 15 so that the rotation of the drum 10 brings at least one hearing 16 under the cowling 15 every turn.

There is also a fan 17 for implementing a step of ventilating (or indistinctly injecting, blowing or blowing) air in the drum 10 and an extractor 18 for carrying out a step of extracting from the drum air 10.

A "fan" is called concisely. It is clear that by "a fan" we mean a set of at least one fan 17, and that by "fan" means a blowing device, configured to blow into the drum

An oxygenated gas composition, in this case air.

Preferably, the fan 17 (air injection nozzle, fan 17, air pump), is activated when it is not in contact with the waste, in this case it is activated when it is in the upper part of the drum 10. Preferably, the radial arrangement of the fans 17 is such that in operation, despite the rotation of the drum, at least one of said fans is always out of contact with the waste, which allows continuous ventilation.

Likewise, we call "an extractor" by brevity, but

It is clear that by "an extractor" is meant an assembly of at least one extractor 18, and that "extractor" means a gas extraction device, configured to extract a gaseous composition, in this case air, from the drum 10 in this case to the atmosphere or an odor treatment device.

The fan 17 and the extractor 18 make it possible to generate a flow of air in contact with the waste in the drum 10. In order for a maximum amount of waste to be in contact with this airflow, it is preferable that the fan 17 and the extractor 18 are arranged near the inlet and outlet ends of the drum 10.

In the figures, the direction of the air flow is represented by solid arrows.

There may be provided a device for selectively closing the gills, comprising for example a shutter movable by hearing and to discover or cover each hearing, or a valve integrated in the fan or in the extractor. By default we provides that the shutter or the valve are closed so as to maintain the tightness of the drum. The shutter or valve is open during ventilation or extraction. The selective closure device may be integral in rotation with the drum.

Since the drum 10 is sealed, if the air was blown or injected by the fan 17 continuously without extraction, there would be overpressure problems when the exit hatch is closed. To avoid this, it provides a controlled operation of ventilation, that is to say the control of ventilation, extraction, or ventilation and extraction of air through a computer.

A first embodiment of a drum 10 is illustrated in FIG. 1A.

This embodiment has the advantage of not having a fan or extractor which is integral in rotation with the drum 10.

The fan 17 is configured to inject air into the drum 10 through a blowing orifice 171. It is stationary, ie not integral with the rotation of the drum 10. Preferably, it is positioned at the inlet of the drum 10, in this case in the feed chute 14. Advantageously, it is positioned downstream of the inlet flap 12 in the direction of travel of the waste and preferably close to the inlet end of the drum 10 for limit the losses in the feed chute 14.

Preferably, the blower orifice 17 is positioned above the mass of the waste 19 in the drum 10. It is also possible to provide an extractor 18. Preferably, the extractor 18 is immobile, positioned at the outlet of the drum 10 and comprises at least one extraction orifice 181, intended to be closer to the outer face of the drum. Preferably, there is provided a plurality of extraction orifices 181, for extracting air through a plurality of orifices, optionally simultaneously. For example, the extractor 18 is connected to the cowling

15, said cowling 15 comprising at least one extraction orifice 181 (Figure 1B).

The extractor 18 makes it possible to channel the flow of air in the drum and to prevent the smelly odors emerge through the feed chute 14 when opening the inlet flap 12.

The extractor 18 is optional. In particular, depending on the waste, there may be no need for gas treatment and extraction system. In this case, the pressure generated by the fan 17 may be sufficient for the air to escape at the opening of a hearing or the outlet hatch.

In addition, a device for selectively closing the openings is provided.

According to a first variant, the device for selectively closing the gills comprises a movable shutter 160 by hearing

16, to discover or selectively cover each hearing. The movable shutter 160 selectively adopts an open position which discovers the hearing 16 and a closed position which covers the hearing 16, preferably sealingly. The passage from the open position to the closed position is illustrated by the solid arrow in FIG. 4. The shape of the movable shutter is illustrated in a triangle, but it can adopt any other shape provided that this form completely covers the hearing 16. closed position. The shutter 160 is rotatable around an axis of rotation 161, in this case radial to the axis of rotation of the drum.

In operation, the movable shutter 160 of a hearing 16 is open when the hearing 16 is facing an extraction orifice 181 and otherwise closed.

For this purpose, it is planned to determine the angular position of each hearing. It is then expected that the open or closed position of the movable shutter 160 of a given hearing is controlled by the angular position thereof, that is to say that the movable shutter 160 is in the open position when the hearing is in the cowling 15 or out of contact with the waste 19, and in the closed position when the hearing is outside the cowling 15 or in contact with the waste 19.

The open or closed position of the movable shutter 160 can be controlled by an automatic opening and closing device, mechanical or electrical.

In this case the opening and closing device is purely mechanical and cam-based and cam follower.

It is also possible to provide a return element such as a spring for returning the movable shutter 160 from the open to closed position or vice versa. For example there is provided a return spring mounted between a movable shutter 160 and the drum 10, a cam integral with the drum 10, and a rail integral with the cowling 15 acting cam follower and whose shape triggers the opening or closing of the flap.

According to a second variant, the device for selectively closing the gills comprises a movable valve integrated in the extractor 18. As the angular position of each hearing is determined, it can be provided that the open or closed position of the movable valve of a given extractor 18 is slaved to the angular position of a given lug 16, that is to say that the movable flap of a given extractor 18 is in the open position when a hearing 16 given is in the cowling 15 or out of contact with the waste 19, and otherwise closed position.

Between the fan 17 and the extractor 18, it is expected to generate a flow of air in the direction of travel of the waste in the drum 10. The air is blown by the fan 17 in the drum 10 in the direction illustrated by the arrows full in Figure 1A.

A second embodiment of a drum 10 is illustrated in FIG. 2A.

In this embodiment, with respect to the embodiment illustrated in FIG. 1A, the fan 17 is here positioned towards the exit of the drum 10. In this case, it is disposed upstream of the exit hatch 13 in the direction of travel. waste and preferably close to the exit end of the drum 10.

According to a first variant, FIG. 2C, provision is made for the fan 17 to be stationary and connected to the cowling 15. Each lug 16 is equipped with a movable shutter 160 identical to that described above and operating according to the same principle as described hereinabove. above: the movable shutter 160 is open when the hearing 16 is facing the blowing orifice 171 and otherwise closed. Preferably, the fan 17 is controlled to operate only when a hearing 16 is open.

According to a second variant, FIG. 2B, provision is made for the fan 17 to be mobile and to rotate with the drum 10. For this purpose, there is provided a fan 17 per hearing 16. Each hearing 16 is connected to a respective fan 17. Each fan 17 may be equipped with a movable valve which functions as the mobile valve of an extractor 18 described above.

Preferably, there is provided a controller for adjusting the flow rate of the fan 17.

In this variant, the fan 17 is preferably operated only when it is at the top of the drum 10, that is to say without contact with the mass of waste 19 at the bottom of the drum 10.

The angular position of a hearing 16 is determined for example by a position sensor, in this case an induction sensor, a mechanical sensor or an optical sensor, internal or external to the drum. For example, with an immobile induction sensor, for example disposed on the cowling 15, as the position of the sensor is known, during the rotation of the drum 10, the passage of a hearing 16 or the fan 17 modifies the measured induction it is then deduced that the hearing 16 or the fan 17 is opposite the sensor. In the case where several sensors are implemented it is preferably provided to arrange them in a radial symmetry.

It may be provided to equip the drum 10 with a plurality of position sensors, at the periphery of the drum 10, for example on the cowling 15, which facilitates their supply of energy.

It can also be provided that a grid is disposed between a given fan 17 and the hearing 16 to which it is connected. The de-clogging of a hearing 16 is provided by the implementation of its fan 17. It can further provide that it emits a jet of air regularly. With a fan 17 equipped with a valve, it can be provided that the pressure of the air jet emitted is sufficient to swing the valve from the closed position to the open position, the stop of the air jet bringing the valve in the closed position. for example by means of return means, for example a spring.

As before, the operation of the non-continuous fan 17 is preferably provided.

Whatever the variant of the second embodiment, it is possible to provide an extractor 18. The extractor 18 is advantageously immobile, positioned at the inlet of the drum 10 and comprises an extraction orifice 181. In this case, the extractor 18 is connected to the feed chute 14.

The air is blown by the fan 17 into the drum 10, in the direction illustrated by the solid arrow in Figure 2A.

Between the fan 17 and the extractor 18, it is expected to generate a flow of air in the opposite direction of the direction of travel of the waste in the drum 10.

The blowing at the outlet of the drum 10 makes it possible to dry the waste, to reduce the humidity contained therein, which is particularly advantageous for very high-level waste or to limit any problems of clogging the waste downstream of the drum 10.

The waste brought into the drum inlet is wet and dries during their residence time in the drum. Whatever the embodiment, the waste output of the drum is drier than those at the drum inlet. However, in the second embodiment, as the fan is disposed toward the outlet of the drum, there is a need for less ventilation energy to dry the waste than in the first embodiment, the drying is better for the same energy of ventilation.

In the case where an extractor 18 is provided, it is simpler to arrange it so that it is not integral in rotation with the drum.

Whatever the embodiment, it is expected to drive the fan 17 and regulate the extractor 18 in the following manner.

Fan control 17

Before being placed in the drum 10, the waste is typically previously stacked, for example in windrow on the ground or in an enclosure such as a container.

There is provided a preliminary step 102 of waste characterization consisting in identifying the nature of the waste. By nature, we mean indistinctly the type, class or typology of waste streams.

The characterization may be implemented by an operator or automatically, on sight or by chemical or physical means; for example, optical means (typically infrared or X-rays).

To characterize the waste, it is also possible to measure the moisture content of the piled up waste; and determining at least one of density, bulk density, density, and bulk density garbage. The measured value and the determined value form a pair of preference values stored in a memory.

Measuring the moisture content can furthermore have the advantage of facilitating the control of the watering of waste in the drum.

The nature of the characterized waste is recorded in a memory, for example as a semantic value (for example "household waste", "sludge", etc.) or as a pair of numerical values (in this case measured humidity packed waste and density of these). The nature of the characterized waste is used as a parameter of a ventilation control algorithm.

It can be expected that the waste is distributed in advance by nature, so that each pile includes a single type of waste, for example a heap of household waste, a pile of sludge, a pile of cardboard and paper, etc. Alternatively, it can be provided that the waste is distributed in batches beforehand, each batch comprising heterogeneous waste, each batch being characterized, several lots being identical.

Preferably, the heaped waste is homogeneous on average over time. The characterization step can advantageously be implemented only at the initialization of the process or in a manner spaced apart over time, for example once a year.

The waste is taken by means of a sampling device, for example a shovel or grapple. The sampled volume defines a unit volume, known, for example by prior calibration. As the volume of waste collected by the grapple is known and constant, and the mass of a volume of waste collected by the grapple is known and constant, we can calculate the apparent density of waste, preferably during an initialization phase.

It is also possible to calculate the apparent density of waste by the ratio between their density and a density of a body taken as reference, in this case water.

The waste collected is dumped into the feed chute 14, then the inlet hatch 12 is closed.

It is proposed to inject air into the drum 10 in a controlled manner.

If too much air is injected, then at the outlet of the drum 10, the air is released into the atmosphere and can generate more undesirable odors, or the air is treated by an odor treatment device. more important or energy consuming than the volume of air to be treated is important.

In addition, the air injection lowers the temperature of the waste 19 in the drum, which disrupts the aerobic fermentation. On the other hand, if not enough air is injected, the oxygen present may be insufficient to guarantee an aerobic fermentation of quality.

Therefore, a solution to this double constraint is proposed here, aimed at optimizing the quantity of air injected, especially when the inlet flap 12 and the outlet flap 13 are closed in a closing step 101.

For this purpose, it is intended to measure the temperature of the waste in the drum 10 by a temperature sensor. Preferably, the temperature is measured continuously. Indeed, during the fermentation, the temperature of the waste evolves. At the temperature of the waste 19 corresponds a stage of progress of the fermentation.

It can be provided beforehand to record in a memory accessible to a computer, a correspondence between a temperature and the stage of progress of the fermentation, for example in the form of a table of digital data or graph. Preferably, it is expected that the table is specific at least to the characterized waste. A set of tables can be provided, each table being specific to a given waste characterization. A table may also be specific to at least one of the parameters of the mass of waste (total mass in the drum, mass of waste per unit volume in the drum or mass of a unit volume), the density of the waste characterized.

The table or tables are stored in a memory, for example in a database.

It is expected to determine the total mass of waste in the drum. The determined value is preferably stored in a memory. For example, the total mass of waste included in the drum 10 is determined by weighing each unit volume or by weighing a unit volume multiplied by the number of unit volumes taken by the grapple.

It is also expected, for a type of waste characterized, a set of matches between a quantity or a flow of air to inject, a mass of waste and a waste temperature. The set of correspondences is presented, for example, in the form of tables in a database, of a graph, or in the form of an algorithm.

Since the temperature of the waste is measured and the mass of waste is known, it is then possible to calculate the quantity of air or the flow of air to be injected, with reference to the set of correspondences for the characterized waste.

The amount of air thus calculated is injected into the drum 10 by the fan 17. Preferably, it is provided in the tables that the quantity of air injected at the beginning of fermentation (low residence time) is greater than end of fermentation (long residence time). The flow of injected air may depend on the characterization of the waste or the volume of waste in the drum.

Preferably, the mass of waste in the drum is substantially constant over time.

It should be noted that the air injected is not intended to dry the waste but optimizes the aerobic degradation of the waste, whose oxygen requirements are translated by the temperature dependence.

In the case of a plurality of fans, provision may be made to distribute the amount of air calculated between the fans 17, typically each fan 17 blowing a quantity of air equal to the calculated quantity of air divided by the number of fans.

The calculation of the quantity of air to be injected and the control of the fan 17 is implemented for example by a computer, the memory comprising the database is connected to said computer. Said memory can be remote from the computer and communicate with it by wired or wireless means.

The internal volume of the drum or the filling rate of the drum are advantageously known and their value stored in a memory accessible to the computer.

Thanks to the invention, if two identical nature of waste have a different density, for example because they have two different moisture content, the amount of air blown is different.

Similarly, thanks to the invention, the amount of air blown can vary depending on the state of degradation of the waste in the drum, this degradation being in particular a function of the temperature inside the tube, the humidity and the nature of the waste.

Regulation of the extractor 18

There is provided a step 107 of extracting air from the drum 10 by an extractor 18.

There may be several modes of regulation of the extractor 18. The extracted air flow may depend on the characterization of the waste or the volume of waste in the drum.

In one embodiment, the extractor 18 is configured to reject the air extracted from the drum 10 into the atmosphere.

In one embodiment, the extractor 18 is connected to a pipe network, typically an odor treatment system. The network of pipes is configured so that the pressure, in this case a negative pressure, is substantially constant and equal to a set pressure.

The extraction rate of the extractor 18 can be controlled 109 as a function of the difference between the set pressure and the measured pressure 108 in the pipe network.

The amount of air extracted from the drum 10 by the extractor 18 may be equal to the amount of air insufflated calculated.

We can provide a step 110 of controlling the extractor 18 as a function of the flow rate of the fan 17.

It can be provided that the injection and extraction of air are made continuously.

It can be provided that the injection and extraction of air are made discontinuously.

The extractor 18 can operate synchronously with the fan 17. The extraction creates a call for air in the drum which ensures a good distribution of the ventilation therein.

The extractor 18 may operate out of phase with the fan 17. For example the operating time of the extractor 18 and that of the fan 17 are the same but offset in time. When the extraction is carried out before the ventilation, a draft is created which ensures a good distribution of the ventilation in the drum. When the ventilation is implemented before the extraction, this generates an overpressure which allows a better extraction of smelly gases. The extractor 18 can operate asynchronously with the fan 17, that is to say with operating times of the extractor 18 and the fan 17 different and offset in time.

The choice of synchronous operation mode, asynchronous or out of phase of the fan 17 and the extractor 18 may depend on the extraction rate and the air injection rate or the type of waste.

Whatever the synchronous, asynchronous or phase-shifted mode of operation of the fan 17 and the extractor 18, the quantity of air injected by the fan 17 is calculated and the air flow rate injected can be chosen, for example as a function of the drum size 10, nature of waste or residence time. The quantity of air extracted and the air flow extracted by the extractor 18 can be chosen, for example also according to the dimensions of the drum 10, the nature of the waste or the residence time, as well as the quantity of air. calculated injected air or injected air flow.

With a sufficient (negative) setpoint pressure, the extractor 18 can compensate for a non-perfect seal of the inlet flap 12 or the extraction orifices (louvre 16s or exit flap 13).

It can be provided that the injection of air or the extraction of air is carried out in cycles. The duration of each cycle is not necessarily the same. It can be expected that the amount of air injected or extracted in a given cycle also depends on at least one of the amount of air injected in the previous cycle and the amount of air extracted in the previous cycle. The present solution improves the aerobic fermentation of the waste in the drum 10 by optimizing the amount of air therein. This improvement is valid not only during the day but even more at night by preventing the drum 10 from going into anaerobic mode. In addition, the extractor 18 makes it possible to channel the gaseous flow and then to treat it at the outlet of the drum 10 more easily.

Glossary

drum 10

main body 11

entrance hatch 12

exit hatch 13

feeding chute 14

cowling 15

gills 16

fan 17

extractor 18

waste 19

Claims

A method of regulating the ventilation of a pre-composting drum (10) comprising an inlet flap (12) and an outlet flap (13), the method comprising the steps of:

introducing (100) waste into the drum (10),

closing (101) the inlet flap (12) and the outlet flap (13);

characterized by further comprising steps of:

characterize (102) in advance the nature of the waste introduced,

measuring (103) the temperature of the waste in the drum,

determining (104) the total mass of the waste (19) contained in the drum,

calculating (105) at least one of the values of an amount of air and a flow rate of air to be injected, as a function of the measured temperature, of the total mass of the waste determined, and the nature of the waste characterized, by reference to a set of matches stored in a memory, and

injecting (106) the calculated quantity of air or injecting air according to the flow rate calculated in the preceding step (105) in the drum (10) by a fan (17), while the inlet flap ( 12) and the exit hatch (13) are closed.

The method of claim 1, further comprising a step of:

- (107) extracting air from the drum (10) by an extractor (18).

3. Method according to claim 2, wherein the extractor (18) is connected to a network of pipes in which pressure is equal to a set pressure, preferably substantially constant, the method comprising the steps of:

measuring (108) the pressure in the pipe network, and

- Control (109) the extraction rate of the extractor (18) as a function of the difference between the set pressure and the pressure measured in the pipe network.

4. Method according to any one of claims 2 to 3, wherein at least one of the steps of the air injection (106) and the extraction (107) of the air is carried out continuously .

5. Method according to any one of claims 2 to 3, wherein at least one of the steps of the air injection (106) and the extraction (107) of the air is carried out in cycles. .

6. The method of claim 5, wherein the amount of air injected or extracted in a given cycle also depends on at least one of the amount of air injected in the previous cycle and the amount of air extracted. in the previous cycle.

7. A method according to any one of the preceding claims, comprising a step (111) of distributing the amount of air calculated between several fans (17), each fan (17) blowing an amount of air equal to a portion of the amount of air calculated.

The method of any one of the preceding claims, comprising a step (112) of generating a flow of air between the fan (17) and the extractor (18): in the direction of the passage of the waste in the drum (10),

- Or in the opposite direction of the scroll of waste in the drum (10).

9. Method according to any one of the preceding claims, wherein the drum (10) is equipped with gills and a device for selectively closing said gills, the preceding comprising steps consisting of:

- Locate the angular position of said gills, and

A computer program comprising program code instructions for implementing the method according to any one of the preceding claims, when said program is run on a computer.