WO2012020434A1 - Apparatus for the treatment of organic waste - Google Patents

Abstract

An apparatus for the treatment of wet organic waste is described, comprising a heated treatment chamber (4) wherein a stirrer is housed (42) and an outflow circuit of vapour-rich air, in- tended to carry on a drying treatment on said waste, wherein said treatment chamber (4) consists of a heated basket - shaped body (40) with an upper mouth (41, 10) sealed in an airtight manner by a relative lid (11) and wherein said outflow circuit is also airtight and puts in communication said heated basket (4) with a condensation unit (5) in turn in airtight communication with a removable drawer (6b) for the collection of condensate.

Description

APPARATUS FOR THE TREATMENT OF ORGANIC WASTE

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Field of the Invention

The present invention refers to a treatment apparatus for the disposal of organic waste, in particular for domestic use. Background Art

As known, the treatment of domestic waste is increasingly becoming of critical importance for city administrations. The increasingly smaller spaces for landfill sites and strict dis- posal laws, together with ecology and environmental conservation issues, impose city administrations to optimise the entire chain of waste collection, differentiation and disposal.

A significant proportion of domestic urban waste consists of so-called "wet" waste, i.e. non-dry organic matter. Typically this waste is separated at user level, in containers or biodegradable bags, and then collected and disposed of by the municipal street cleaning and refuse disposal services in suitable conversion areas, where the waste decomposes into compost or other recyclable organic material.

Of course, this requires to organise a specific collection service, often carried out "door-to-door" to avoid the accumulation of large amounts of perishable organic material, which would be detrimental from a hygienic point of view. As known, users are not keen on having to manage wet waste collection, as it is biologically active material rich in water and hence tends to perish, giving off odour and releasing sewage. Especially in a flat, wet waste collection implies a series of drawbacks connected with odour, space occupation and the centralised management of waste waiting for the collection by the municipal street cleaning and refuse disposal services (collection bags are subject to attacks by stray animals) . Those who have an outdoor space often resort to composters for the disposal of organic waste; but also composters are not devoid of problems, as they are a receptacle for insects and wild animals and a source of odours, especially with high outdoor temperatures.

In order to solve these problems, devices for the treatment of organic waste have been proposed to be installed within indi- vidual households. These apparatuses typically have the purpose of drying the organic material as much as possible, so as to reduce its volume and remove the bacterial flora which is the source of odours. They comprise a loading compartment, where the organic material is poured, provided with mixing means, for example in the shape of a rotating arm. The compartment is heated in order to cause the drying of the organic material. The heated air, rich in humidity, is caused to condense so as to extract and then dispose of the liquid component. Ideally these appara- tuses should solve the problem of wet waste collection, since they greatly reduce the volume of waste, producing as a result a relatively small amount of compost, which can be used again for the growing of plants or to be disposed of with dry waste.

Typical examples of such apparatuses are described in US5925321A, US2003036190A, WO08150059A, US5534042A.

Prior-art apparatuses, however, are subject to some drawbacks. Firstly, they are conceived with a complex and bulky construction, especially in a vertical direction; as a matter of fact, they normally provide a waste collection compartment, be- low which a series of members for controlling, channeling and unloading waste are arranged, which remarkably increase the vertical bulk thereof. Moreover, they provide a discharge of the condensation water extracted from the organic material, which discharge must be connected to a sewage drain, typically in cor- respondence of a sink drain: this implies a specific installation which is often not within reach of the common user. Finally, they are often a source of odours, due to aerobic bacterial digestion, which leak out from the loading compartment and/or condensation drain.

Normally these drawbacks do not represent a source of worry for manufacturers, because it is commonly believed that such apparatuses are meant for installation in an isolated area underneath a sink, in the suitable compartment normally provided for waste collection. In actual fact the Applicant has detected that users do not appreciate such traditional approach. As a matter of fact, the compartment below a sink is not easily accessible, especially if electric switches must be activated; moreover, lo- calised heating, within a compartment which normally provides no ventilation, is a source of worry; again, the need to call a plumber or other expert for the correct connection of the apparatus to the sewage drain discourages from installing the appa- ratus; finally, the exhalation of odours from the condensation drain or from the loading door leads to quickly abandon this disposal practice.

Summary of the Invention

The object of the present invention is hence that of pro- viding an apparatus for the treatment of organic waste which overcomes the drawbacks just cited. In particular, it is meant to provide a sufficiently economical and compact apparatus, suitable for treating effectively at least 2-3 Kg of organic waste without producing any odour and ready to use, i.e. which requires no specific connection or installation.

Such objects are achieved through an apparatus as described in its essential features in the attached main claim.

Other inventive aspects of the apparatus are described in the dependent claims.

In particular, according to a first aspect of the invention, an apparatus for the treatment of compostable organic waste is provided, comprising a heated treatment chamber wherein there is housed a stirrer and a circuit for the outflow of vapour-rich air, intended to perform a drying treatment on said waste, wherein the treatment chamber consists of a heated basket-shaped body with an upper mouth sealed be a lid therefor and wherein the outflow circuit is also a sealed one and puts in communication said heated basket with a condensation unit which is in turn in sealed communication with a removable drawer for the collection of condensation.

According to another aspect, the apparatus provides that the heated basket-shaped body houses a mixing arm rotatably mounted with a substantially vertical axis, a gearmotor assembly being arranged below said basket-shaped body and apt to drive into rotation at least a first shaft of the mixing arm.

According to a further aspect, the basket-shaped body is in communication with an auxiliary chamber, arranged on a side thereof, which houses a helical screw apt to define a rising hopper. The auxiliary chamber ends above with an ejection opening communicating with a flanged mouth facing downwards and communicating in an airtight manner with a removable drawer for the collection of dry residue. The helical screw is preferably integral in rotation with a displacement tooth arranged in the proximity and downstream of said ejection opening to push dry residues towards said flanged mouth.

According to a preferred aspect, the auxiliary chamber com- municates with the inside of said basket-shaped body through an opening flush with the bottom surface of said basket-shaped body .

According to another aspect, the gearmotor assembly drives into rotation also a second shaft integral in rotation with a driving shaft of said helical screw and said helical screw has a longitudinal rotation axis inclined with respect to the vertical line of an angle ranging between 15° and 80°.

According to a further aspect, the condensation unit is arranged on a rear side of said basket-shaped body, opposed to said auxiliary chamber, and is connected - through an inlet connection - to the inner compartment of said basket-shaped body and also through a diverging vent connection towards a condensation chamber of said unit.

According to another aspect of the invention, the condensa- tion unit of the apparatus comprises a condensation chamber provided with a cold wall in contact with a flap dissipator. Preferably in the cold wall there are installed Peltier cells.

According to a last preferred aspect, the heated basket- shaped body consists of a lower, metal, vase-shaped portion and of an upper lid-shaped portion, mutually joined in an airtight manner, the upper lid portion comprising a loading opening consisting of a relief ribbing ending with a perimeter seal.

Brief Description of the Drawings

Further features and advantages of the apparatus according to the invention will in any case be more evident from the following detailed description of a preferred embodiment of the same, given by way of example and illustrated in the attached drawings, wherein:

fig. 1 is an exploded view of the apparatus according to the invention;

fig. 2 is a front perspective view of the treatment chamber of fig. 1;

fig. 3 is a perspective view from the rear side of the chamber of fig. 2;

fig. 4 is a rear perspective view of the treatment chamber with the lid portion removed;

fig. 5 is a cross-section view of the chamber of fig. 2 taken from below;

fig. 6 is a longitudinal-section view, passing through the centre of rotation of the mixing arm, of the chamber of fig. 2; and

fig. 7 is a block diagram of the operation of the condensation unit.

Fig. 1 shows an overall view of the fundamental components assembled in the apparatus according to the invention.

An outer bodywork casing consists of two parts, a lower one la and an upper one lb which hold within the operative components of the apparatus. Lower bodywork component la acts as basement of the apparatus and has, for such purpose, a plurality of resting feet la'.

Within the bodywork casing, above basement la, there are arranged a box 2 housing electronic circuit boards, a gearmotor assembly 3, a treatment chamber (mixing and toasting) 4 and a condensation unit 5. A plurality of electric connections (not shown) apt to mutually connect the various components is further provided, with also a small base 2a for taking and distributing the electric supply from a network cable.

In the base portion la of the bodywork, on the front, there are furthermore provided two openings for the introduction of removable drawers 6a and 6b, for dry residues and for the collection of condensate, respectively. The two drawers can slide horizontally and can hence be introduced into basement la and be fully extracted. The drawer for the collection of condensate 6b is put in airtight communication, for example through a pipe (not shown), with condensation unit 5. As better described further on, the drawer for dry residue 6a has an upward-facing inlet, meant to^' abut in an airtight manner with a lower outlet of the hopper system of chamber 4.

Due to the different nature of the material which they are meant to receive, the two drawers are not required to have the same size. Typically, the drawer of condensate 6b has a greater volume than the drawer of dry matter 6a.

According to a preferred embodiment, condensate drawer 6b houses inside a float system, suitable to provide an overflow signal to the apparatus control system. When the preset maximum level is reached, the signal generated by the rise of the float prevents the execution of a new operation cycle of the apparatus, until the drawer is emptied. Advantageously, with the view of avoiding any complication and source of disruption of sealing, the float is of a type equipped with proximity switch: for example it is equipped with a magnet which determines the generation of an overflow signal when it is moved closer to a sensor arranged outside above the drawer. In this case it is not necessary to provide any electric contact entering the condensate drawer, because the effect of the magnetic field propagates also through the wall thickness.

Bodywork upper portion lb has a loading opening 10 which is closed by a door 11. According to the invention, opening 10 has a seal or perimeter lip suited to seal against the lower surface of door 11. Similarly, in the inner part of opening 10 a second seal or sealing lip is provided, suitable to rest in an airtight manner against a perimeter edge of a corresponding loading opening 41 provided in the upper part of chamber 4.

Fig. 2 shows in greater detail the assembly of chamber 4 for the treatment and toasting of organic waste, as well as adjacent condensation unit 5.

A main body 40 of the toasting chamber has a generic basket shape, open above through a loading mouth 41.

From a construction point of view, it is preferable for basket-shaped body 40 to be obtained in two pieces, mutually joined in an airtight manner: a lower, vase-shaped portion and an upper, lid-shaped portion. The lower portion of basket 40 (fig. 4) is advantageously made of metal material, for example of an aluminium alloy, so as to facilitate the conduction of heat from the heating system; the upper lid portion can instead be made of plastic material and be mounted in an airtight manner, for example arranging in between a gasket, on the underlying metal vase.

Loading mouth 41 is obtained through a projecting ribbing in the lid portion. As already mentioned, loading mouth 41 is provided, along the perimeter edge, with a sealing gasket 41a, suitable to define a seal with the above-lying opening of bodywork upper portion lb.

In the walls of basket 40, in particular of the lower metal portion thereof, there are provided electric resistances suited to internally heat the compartment of chamber 4 as high as a toasting temperature of about 120-130°C. Alternatively, should the machine be sufficiently large, a hollow space is provided in the walls of basket 40, wherein oil is apt to circulate, heated in turn by a separately arranged heater.

In the front part of basket 40, preferably offset by about

20° to the left, an auxiliary chamber 40a is provided which acts as discharge hopper, as will be detailed further on.

Inside the main compartment of basket-shaped body 40 a mixing arm 42 (clearly shown in fig. 6) is rotatably mounted. Arm 42 is generically U-shaped, with the two U legs 42a and 42b brushing the bottom surface of basket 40 and rising back up to different lengths. One of the two legs 42a of arm 42 rises back up to a radial distance from the centre of rotation substantially equivalent to that of the inner surface of basket 40. The opposite leg 42b of arm 42 rises back up at a smaller radial distance, as clearly visible in fig. 6, thus making the stirring action more effective.

Leg 42 is preferably made of hard metal material, profiled so as to mix - but also to grind and crumble - the material to be treated. This allows to widen the type of organic waste treatable by the apparatus, for example, in addition to pulpous and soft material, also nuts, shellfish shells, and fish bones, which are typically tenacious materials.

Arm 42 is rotatably mounted on a shaft axis 43, coming from below-lying gearmotor assembly 3, which will be illustrated in greater detail further on. Arm 42 is intended to rotate on shaft axis 43 at modest speed, of the order of 12-15 rpm.

In the rear part of basket 40 condensation unit 5 is housed, which is contained in a bulk of a height not above that of basket 40. Condensation unit 5 communicates with the inside of basket-shaped body 40 through two ports, a vent one 44a and an inlet one 44b. The two ports 44a and 44b are obtained in the upper part of basket-shaped body 40 (see figs. 2 and 3) and communicate with two respective elbow hoses 45a and 45b, preferably obtained integrally with the lid portion of basket 40.

At the exit of elbow hoses 45a and 45b there is engaged, in an airtight manner, the mouth of respective vent and inlet pipes of condensation unit 5. In particular, a vent pipe 51 opens funnel-like (square section, as can be seen in fig. 2 and in the section of fig. 5) starting from hose 45a, so as to facilitate a first cooling due to expansion of the air extracted from chamber 40. In the lower terminal part of vent pipe 51 a fan or pump 51a is installed, suitable to extract humid air from the chamber inside basket 40 and to push it towards an actual condensation chamber 52. Said condensation chamber, of a flat shape, is in communication also with inlet hose 45b, arranged on the opposite side with respect of pipe 51, through an inlet pipe, also engaged in an airtight manner. The rear side of condensation chamber 52 is sealed by a cold condensation plate 53, typically consisting of an aluminium plate. In the lower part of condensation chamber 52, preferably on the side corresponding to reintroduc- tion connection 45b, a short discharge tube 54 is provided, wherefrom condensed water flows out. Discharge tube 54 is put in airtight communication with the drawer of condensate 6b, as previously mentioned, for example by means of a small pipe of plastic material.

On the rear side of cold plate 53 a flap dissipator 55 is arranged, of a type known per se, preferably forcedly cooled by a pair of small fans 56. According to a preferred embodiment, between cold plate 53 and dissipator 55 a pair of Peltier cells 57 is also arranged, suitably energised by corresponding electric connectors (not shown) .

Fig. 7 shows a block diagram of the operation of the condensation cycle obtained with condensation unit 5. Hot air, rich in vapour extracted from the organic waste in chamber 40, is extracted by pump 51a through vent port 44a and caused to pass into unit 5. The hot air undergoes a first cooling by expansion in pipe 51 and a second cooling upon contact with cold plate 53 in condensation chamber 52. The cooling causes water condensation (more or less rich in organic molecules, such as proteins, but free from bacteria - killed by the previous thermal cycle in chamber 40) , which is then drained and channelled - through tube 54 - to the drawer of condensate 6b. The humidified air is reintroduced into chamber 40 through inlet port 44b and hose 45b.

With reference to fig. 6, the gearmotor assembly below basket-shaped body 40 can be appreciated. In the gearmotor assembly an electric motor M is integrated, which drives into rotation a series of transmission gears which, in turn, drive two drive shafts. On one side shaft 43 for the rotation of mixing arm 42. On the other side, the transmission drives an auxiliary shaft 31 of an auger or helical screw 44 rotatably mounted within cylindrical auxiliary chamber 40a.

According to a preferred embodiment, in order to reduce bulks and achieve a more performing transmission, auxiliary shaft 31 consists of two parts, a first part 31a mounted on bearings according to an axis parallel to main shaft 43, a second part 31b, inclined according to the longitudinal axis of auxiliary chamber 40a and connected to the first part 31a through a cardan joint or other bevel gear. The first part 31a and the main shaft 43 of mixing arm 42 are mutually connected in rotation,, for example through a transmission belt 32 acting on two transmission wheels 33 and 34.

Preferably, both shafts 31 and 43 are provided with a gasket at the intersection with the bottom of auxiliary chamber 40a and of basket 40, respectively. This ensures a perfect, airtight seal also in the lower part of toasting chamber 4.

Auxiliary chamber 40a projects along the inclined wall of basket-shaped body 40, forming a hopper-like channel wherein helical screw 44 is rotatably mounted. For bulk optimisation and an efficient operation of the rising hopper, helical screw 44 has a rotation axis inclined to the vertical by an angle ranging between 15° and 80°, preferably of the order of 20-30°.

As visible in figs. 4 and 6, auxiliary chamber 40a is closed below and above by a partition 44a which defines a par- tial ejection opening 44b. Shaft 31b of helical screw 44 pro^¬ jects slightly above partition 44a: on the projecting end a pushing tooth 44c is keyed on, integral in rotation with shaft 31b, the usefulness of which will be illustrated in the following .

Closing partition 44a is arranged perpendicularly to the rotation axis of helical screw 44 and hence inclined with respect to the horizontal: it hence determines an inclined sliding surface, the usefulness of which will be understood in the following of the description.

Moreover auxiliary chamber 40a is open on one side towards the inner compartment of basket 40: in particular it has an inlet port 45 which communicates with the inner chamber of basket 40 flush with the lower area, i.e. it connects with the bottom surface of basket 40.

In the top part, auxiliary chamber 40a, which ends slightly below the top of basket 40, is further sealed in an airtight manner by a cap 46. Said cap encloses the top area, where pushing tooth 44c is housed, as well as a side portion of flanged mouth 47, projecting frontally from auxiliary chamber. The cap is preferably integral with the lid portion of basket 40 and is fastened to auxiliary chamber 40a by removable fastening means, such as Allen screws 46a, so as to be able to be disassembled and allow access to the below-lying auxiliary chamber. Also in this area a seal below cap 47 is suitably provided so as to guarantee an airtight seal.

Similarly, also partitioning 44a is removably fastened, so that it may be disassembled to remove helical screw 44 and fa- cilitate any maintenance work.

Flanged mouth 47 opens downwards (throughout the present application, the terms "down" and "up" refer to the attitude of the apparatus in its normal operation condition) and is coupled with a further collector 48 which puts in communication - always in an airtight manner - auxiliary chamber 40a with the below- lying drawer of dry residues 6a.

Since collector 48 is arranged substantially vertically above drawer 6a, the pouring off of material from the top of the auxiliary chamber to the drawer occurs by simple fall. It can be appreciated (fig. 6) that the drawer of dry residue 6a is housed in the space below auxiliary chamber 40a which is inclined vertically, thus obtaining an advantageous compacting of bulks.

During its standard operation, helical screw 44 is caused to rotate so as to push downwards any material it may catch: thereby a sort of recirculation of the material is obtained, which material is pushed into the auxiliary chamber by rotating arm 42 upon its passing in front of side opening 45.

When the operation cycle is completed, it is provided to invert the direction of rotation of the motor and hence of screw 44 and of arm 42. With such rotation, screw 44 tends to lift the material upwards, which material is pushed into the auxiliary chamber 40a by arm 42. At the end of the cycle, hence, the dry and crumbled material is lifted by helical screw 44 until it comes out of the opening 44b of partition 44a. In this position, rotating tooth 44c provides to push the dry material towards flanged mouth 47, along the inclined plane of partition 44a, so as to cause it to fall into drawer 6a.

Based on the detailed description reported above, it is now possible to understand the operation of the apparatus.

The user opens airtight door 11 and easily introduces from above the organic waste into basket 40. Due to its specific construction, the machine is capable of accepting a wide variety of different waste, except very hard and bulky ones (for example large cattle bones) . In the household version, the apparatus has a basket capable of receiving about 2-2.5 Kg of residue.

Upon starting, a management programme starts the heating of basket 40, as high as 110-120°C, controlling the temperature thereof through a thermocouple. At the same time gearmotor 3 is put into motion; so that arm 42 and screw 44 are driven into rotation at the desired speed.

The mixing and toasting cycle of the organic waste can last on average 2.5-3 hours for a load of the order of 2-2.5 Kg. According to a preferred embodiment, the apparatus comprises a humidity sensor, arranged inside the airtight chamber of basket 40, so as to detect inner air humidity: when an acceptable, pre- set threshold value is reached (for example 15% relative humidity) , the toasting cycle is ended. Typically, at the end of the cycle the organic waste has lost 75-80% of weight, which has been collected as condensed water in the suitable drawer.

At the end of the toasting cycle, the rotation of the motor is inverted, so as to evacuate the basket chamber and pour the dry residue into the suitable drawer. At this point the machine can be stopped and is prepared for the execution of a new cycle.

Depending on the user' s preferences and on the amount/nature of the organic waste treated, the drawers for the collection of the condensate and of the dry matter may be emptied upon each operation cycle or more occasionally, provided the fact that the safeguard represented by the overflow system in the condensate drawer exists.

As can be guessed, the apparatus according to the invention is very effective and convenient, allowing to fully achieve the objects set forth in the premises.

The apparatus is compact and free-standing; it requires no connection to the sewage system and is hence immediately operative and requires no particular installation devices. The gear- motor arrangement which simultaneously controls the main stirrer and the lifter arranged adjacent to the basket, on the front, is particularly compact and effective for mixing the organic waste and for ejecting the dry matter. In a short time the apparatus is capable of treating the entire volume of organic waste pro- duced by a family in the course of a day, providing as byproduct condensation water, which can be disposed of or used for watering plants, as well as a very low volume of solid material, which may be used as compost or disposed of in the dry waste. Neither one of the two by-products gives off odours, nor does it contain bacteria, because it has undergone a sterilising thermal treatment. Since the entire mixing and toasting chamber and the various pipes are assembled in an airtight manner and form a closed circuit, also during treatment no odour is released.

However, it is understood that the invention is not limited to the particular configuration illustrated above, which represents only a non-limiting example of the scope of the invention, but that a number of variants are possible, all within the reach of a person skilled in the field, without departing from the scope of the invention.

For example, it is not ruled out that, instead of a condensation unit with Peltier cells, a condensation unit employing a classic frigorific cycle may be similarly used.

Moreover, although in the description reference has always been made to a finished bodywork casing, it is not ruled out that the operating components of the apparatus may be assembled in a raw frame to be fitted into a piece of furniture; for exam- pie, the reduced vertical bulk of the invention would advantageously allow the introduction into a drawer of a piece of kitchen furniture.

Claims

1. Apparatus for the treatment of wet organic waste, com^¬ prising a heate'd treatment chamber (4) wherein a stirrer and an outflow circuit of vapour-rich air are housed, intended to carry on a drying treatment on said waste, characterised in that said treatment chamber consists of a heated, basket-shaped body (40) with an upper mouth (41, 10) sealed in an airtight manner by a relative lid (11) , and in that said outflow circuit is also arranged in an airtight manner and puts in communication said heated basket (4) with a condensation unit (5) in turn in airtight communication with a removable drawer (6b) for condensate collection .

2. Apparatus as claimed in claim 1, wherein said heated, basket-shaped body (40) houses a mixing arm (42) rotatably mounted with a substantially vertical axis, below said basket- shaped body (40) a gearmotor assembly (3) apt to drive into rotation at least one first shaft (43) of said mixing arm (42) being arranged.

3. Apparatus as claimed in claim 2, wherein said basket- shaped body (40) is in communication with an auxiliary chamber

(40a) arranged on a side thereof, said auxiliary chamber housing a helical screw (44) suited to define a rising hopper.

4. Apparatus as claimed in claim 3, wherein said auxiliary chamber (40a) ends above with an ejection opening (44b) communi- eating with a flanged mouth (47) facing downwards and communicating in an airtight manner with a removable drawer (6a) for the collection of dry residues.

5. Apparatus as claimed in claim 4, wherein said helical screw is integral in rotation with a displacement tooth (44c) arranged in the proximity and downstream of said ejection opening (44b) to push dry residues towards said flanged mouth (47) .

6. Apparatus as claimed in any one of claims 3 to 5, wherein said auxiliary chamber (40a) communicates with the inside of said basket-shaped body (40) through an opening (45) flush with the bottom surface of said basket-shaped body (40) .

7. Apparatus as claimed in any one of claims 3 to 6, wherein said gearmotor assembly (3) drives into rotation also a second shaft (33) integral in rotation with a drive shaft (31b) of said helical screw (44) .

8. Apparatus as claimed in any one of claims 3 to 7, wherein said helical screw (44) has a longitudinal rotation axis inclined with respect to the vertical of an angle ranging between 15° and 80° .

9. Apparatus as claimed in any one of claims 3 to 8, wherein said condensation unit (5) is arranged on a rear side of said basket-shaped body (40) , opposite to said auxiliary chamber (40a) , and is connected through an inlet hose (45b) to the inner compartment of said basket-shaped body (40) .

10. Apparatus as claimed in claim 9, wherein said condensation unit (5) is connected to the inner compartment of said basket-shaped body (40) also through a vent hose (45a) which di- verges towards a condensation chamber (52) of said unit (5) .

11. Apparatus as claimed in any one of the previous claims wherein said condensation unit (5) comprises a condensation chamber (52) provided with a cold wall (53) in contact with a flap dissipator (55) .

12. Apparatus as claimed in claim 11, wherein on said cold wall (53) Peltier cells (57) are installed.

13. Apparatus as claimed in any one of the previous claims, wherein said heated, basket-shaped body (40) consists of a lower, vase-shaped portion and of an upper lid-shaped portion, mutually joined in an airtight manner, the upper lid portion comprising a loading opening (41) consisting of a relief ribbing ending with a perimeter gasket (41a) .