CH620606A5 - Installation for converting household waste into a combustible product - Google Patents

Description

The present invention relates to an installation for obtaining a combustible product starting from household waste.

Currently, household waste collected is treated in different ways, namely:

a) Household waste is dumped as collected in landfills in which it can be partially burned, leading to atmospheric pollution by the smoke released, and also possibly to pollution of groundwater.

b) Household waste, after sorting, is transformed into compost, but this process only transforms around 60% of the waste, the remaining part, or around 40%, having to be destroyed by incineration in landfills provided for this purpose. effect.

The use of compost is currently not sought, since its implementation requires a large workforce for the various loading, handling, transport, spreading.

c) The waste is incinerated for no other purpose than to transform it into smoke; However, such a way of doing things is expensive, since it requires appropriate installations, equipped with devices capable of allowing correct purification of the fumes.

d) Household waste is incinerated in facilities provided for this purpose with recovery of the energy released.

However, this technique has drawbacks, and in particular that of requiring large investments which cannot be borne by small and medium-sized cities.

Furthermore, the energy produced cannot be stored, and the energy yield is relatively low, since it has been observed that 8 t of household waste was substantially equivalent to 11 of fuel oil.

However, it has also already been proposed to manufacture combustible products from household waste, these products being able to be stored in the form of briquettes.

Thus, French patent No. 492026 describes a process for preparing an artificial combustible product from household waste, consisting of reducing said waste to a pulverulent state and then, after drying, adding to this household waste thus reduced combustible residues of all kinds such as coal, lignite, peat, etc. The product thus obtained is then mixed with agglomerants such as tar, resins, pitch, and optionally with a suitable amount of sodium chloride, intended to promote combustion. The mixture is subjected to vigorous stirring, so as to obtain a homogeneous mass which is then heated and briquetted by molding and compression.

In French patent N ° 385428 which relates to an apparatus for manufacturing combustible briquettes with household refuse and various agglomerants, the refuse is first sieved to extract from the latter the substances harmful to the manufacture of briquettes, then crushed, mixed and kneaded with incorporation of agglomerants such as pitches, black molasses or other starch powders.

From what is explained above, it is noted, on the one hand, that the various known techniques for disposing of waste

5

10

15

20

25

30

35

40

45

50

55

60

65

3

620,606

household goods either lead to prohibitive cost prices for small and medium-sized agglomerations or, on the other hand, it is necessary to include, in cases where it is sought to obtain a storable combustible product, agglomerants to bind household waste previously reduced in appropriate facilities.

The subject of the present invention is an installation for transforming household waste, such as collected, into a combustible product suitable for easy handling, this installation being, by its affordable cost, capable of being installed in particular, but not exclusively, at neighborhood of small and medium-sized towns.

An installation according to the invention for transforming household waste into a combustible product, by successive treatments of this waste in apparatus capable of selecting combustible waste, and of transforming this waste into a combustible product, is characterized in that it comprises , from upstream to downstream - ■ upstream being a location where the waste is brought as collected and downstream a location where the combustible product is stored - a shredder capable of breaking apart in particular the plastic bags containing waste, a screen capable of selecting waste according to its density, high density waste being discarded, a crusher capable of reducing the waste thus selected to particles, a magnetic separator capable of extracting metal products from particles iron, and a die press capable of transforming the particles into granules by agglomeration.

According to one embodiment of the invention, means for routing the products from the screen to the magnetic separator are constituted by a pneumatic device comprising two cyclones placed in parallel, a first cyclone serving the inlet of the mill, while the second cyclone is connected to the magnetic separator via a lock, this second cyclone being capable of placing the lower part of the first cyclone into depression.

According to another embodiment of the invention, a mixer is arranged between the magnetic separator and the press; associated with this mixer is a storage silo for an additional product to neutralize harmful substances.

Advantageously, the aforementioned product stored in the silo will be calcium carbonate intended to combine with chlorine.

In this installation, household waste as collected, that is to say in which there are in particular more or less bulky metal objects, glass bottles, plastics, plants, etc., are transformed after extraction. non-combustible waste, carried out along the way, in combustible granules, and this under remarkable sanitary conditions since at no point in the treatment, the waste is not in the open air.

In addition, the workforce is extremely reduced since, in fact, it is only a question of monitoring the proper functioning of the various devices.

The problem of the destruction of household waste, especially in small and medium-sized towns, is therefore solved in a practical way, this destruction leading to a positive result, since it leads to the recovery of a combustible material that can be easily handled and stored. , which can be burned at any time in any location.

It should be emphasized that the granules obtained have a configuration and dimensions enabling them to be handled using conventional devices, such as bucket elevators, conveyor belts, endless chains, etc., hence easy handling and low transport costs.

The fuel pellets are in the form of sticks suitable for storage in conventional silos where they are aerated, and capable of being stored for periods of the order of one year.

This possible storage for a long period therefore leads to remarkable flexibility of use, since stocks can be built up, allowing the use of sticks on demand.

Another important advantage of the fuel sticks obtained is that they can be distributed by pneumatic circuit in boilers where they burn up, for the most part, by being in suspension, practically without ash formation, since they are formed by particles of paper, cardboard, rags, wood, various plants and other products, completely combustible.

The characteristics and advantages of the invention will become apparent from the description which follows, given by way of example with reference to the accompanying drawing plates in which:

fig. 1 illustrates in schematic elevation an embodiment of an installation according to the invention;

fig. 2 is a schematic view in horizontal section of the shredder along a plane passing through the line II-II of FIG. 1;

fig. 3 is a view of a tooth of the shredder along the part surrounded and indicated by III in FIG. 2;

fig. 4 is a view of a cross section of the screen, this section passing through the line IV-IV of FIG. 1;

fig. 5 is a partial view of the teeth of the mill;

fig. 6 is a vertical sectional view of the lock disposed between the second cyclone and the magnetic separator;

fig. 7 is a schematic view in vertical section of the magnetic separator;

fig. 8 shows a schematic vertical section of the die press; fig. 9 is a partial detailed view in vertical section of the die equipping the aforementioned press, and FIG. 10 illustrates in perspective the combustible product obtained, FIGS. 2 to 9 being shown on a larger scale compared to FIG. 1.

The installation shown, for transforming combustible waste found in household waste, such as collected, into pellets, comprises from upstream to downstream a chain of processing devices, each having a determined function, upstream being the end of the chain receiving the waste, as collected, and the downstream being the end of the chain where the granules obtained are stored.

Referring to fig. 1, household waste, as collected, is poured into a hopper 10 advantageously provided with a distribution drawer indicated diagrammatically at 11 and the base of which opens onto a shredder generally indicated at 12.

This shredder, which is also visible in FIG. 2 in horizontal section, has the essential function of breaking open the cardboard boxes and plastic bags in which there is household waste; it comprises, in a casing 13 and supported by bearings 14-15, 16-17, two parallel shafts 18-19, on each of which are advantageously secured two helical turns 20-20A, 21-21A, provided peripherally with removable teeth 22 .

The bearings of at least one shaft, for example the bearings 14-15, are mounted on runners in such a way that the distance between the shafts 18-19 - and hence the spacing of the turns of the propellers - can be changed as desired. by displacement of the shaft 18 in the direction of arrow F, each of the aforementioned shafts being moreover equipped with a reduction gear 24-25 fixed on a rotational drive pulley 26-27, these pulleys being coupled to drive means in rotation, not shown here.

The casing 12 is shaped in the lower part to form an evacuation chute 30 opening substantially in the axis of a screen known under the name Trommel; this screen is indicated overall by the reference 32 and it includes:

- A fixed cylindrical casing 33 whose axis is inclined to the horizontal, and which has, along lower generatrices, an opening 34 to which is connected a funnel-shaped deflector 35;

5

10

15

20

25

30

35

40

45

50

55

60

65

620,606

4

- A cylindrical drum of revolution perforated 36, installed coaxially with the casing 33, being capable of rotation inside thereof by means of roller bearings or similar systems 37-38, interposed between the rotary drum forming a sieve 36 and the cylindrical envelope 33, and this in the immediate vicinity of the ends.

The screen is coupled to rotational drive means according to the arrow F1 (fig. 4) which are not shown here, but which can advantageously be constituted by a toothed ring associated with the screen and a pinion wedged on a clean motor member. to cooperate with the crown through an opening provided for this purpose in the envelope 33.

The chute 30 of the shredder opens into an opening 40 formed in a lateral face 33A of the envelope 33, this opening being situated substantially in the axis of the screen,

it being understood that the screening designation includes the casing 33 and the screen 36.

On the side opposite to the lateral face 33A, the lateral face 33B of the envelope has an opening 41 offset downward relative to the axis of the screen.

By the lateral face 33B of the envelope is engaged a tubular section 42 comprising a longitudinal opening 43 oriented towards the bottom of the screen; this tubular section extends over the greater part of the length of the screen and it is connected to a conduit 44 of a pneumatic device, this conduit comprising a bypass 45. The conduit 44 is connected to the inlet of a first cyclone 46 capable of creating in this conduit a suction current directed according to the arrows F2, so that the waste brought into the upper part of cyclone 46 is directed towards a crusher indicated as a whole at 50.

The crusher comprises, in a casing 51, a rotor 52 capable of being rotated by a pulley 53 wedged at one end of a shaft 54 carried by bearings 55 associated with the casing 51 and the other end of which carries a flywheel 56.

The above-mentioned rotor has, on its outer surface, a plurality of circular grooves 57 (see also FIG. 5), at the bottom of which are arranged, along a section of propeller, at least two series of diametrically opposed knives 58.

The consecutive grooves therefore form between them circular ribs 59 which also receive two series of diametrically opposite knives 60, knives aligned with the knives fixed to the bottom of the grooves.

The casing carries, meanwhile, a comb 62 of profile corresponding to that of the aforementioned knives, so that the waste is reduced to particles, passing through this crusher, from where it falls into a deflector 63 connected by a tube. 64 to a second cyclone 65 whose function is similar to that of cyclone 46, so that the particles are transported along the arrowed path F4 in a lock 67 arranged at the base of the second cyclone.

This lock, clearly visible in vertical section in fig. 6, comprises a casing 70 comprising a first opening 71 in the upper part, and a second opening 72 in the lower part; between these openings is arranged a rotating member comprising, for example, six pallets 73 mounted radially on a shaft 74 journalled in bearings (not visible here) carried by the casing.

The aforementioned shaft 74 is coupled by chain transmission 75 to a drive means 76 and the pallets - between the aforementioned openings - have their end edges which cooperate with two walls in the form of circular sectors 77-78, so that compartments C of a determined volume are closed when the pallets are opposite said circular sectors. The drive means 76 is capable of ensuring a step-by-step rotation of the shaft 74, so as to allow correct filling of the compartments C, which filling is carried out through the opening 71, while the extraction of the particles present in a compartment is carried out by gravity through the opening 72,

from where they are admitted in a magnetic separator indicated as a whole in 80.

The magnetic separator, clearly visible in fig. 7, comprises, in a frame 81, an inlet chute 82 in the form of a funnel equipped at the base of a regulating flap 83 with control means 84. The bottom of the funnel is located substantially at the right of a cylinder 85 capable of rotation on an axis 86 by means of drive means 87-88.

Inside the cylinder is disposed a sector 89 of magnetic metal which is fixed and occupies substantially a half-circumference.

The base of the casing 81 is equipped with two corridors 90-91 for discharging the particles, one of the corridors, in this case the corridor 90, receiving the metallic waste selected by the magnetic sector, and the other corridor 91 , the remaining particles, these then being directed to a mixer indicated as a whole by the reference 95.

This mixer is constituted by a semi-cylindrical tank 96 inside which are arranged, on a common shaft 97, two filiform helices respectively 98-99, coaxial and with reverse pitch, the shaft 97 being capable of being driven in rotation by an engine 100.

The bottom of the tank has an opening 101 for discharging the mixed particles towards a press generally indicated at 102, visible in particular in FIG. 8.

The aforementioned press comprises, resting on a frame 103, a circular tank of revolution 104 with radial opening 105; inside this tank, a vertical shaft 106, co-axial with the axis thereof, carries, by means of horizontal arms 107 vertically offset, a pair of rollers 108, 109 freely rotatable on vertical axes respectively 110-111.

The shaft 106 and, consequently, the rollers 108-109, are capable of being driven in rotation by a motor means not shown, the rollers running past the inner wall of a circular die 113 associated with a fixed plate 114 linked to the chassis by a spacer 115 forming a thrust ball bearing for the shaft 106.

Between the bottom of the tank 104 and the plate 114 is disposed a horizontal arm 116 whose axis of rotation is coaxial with the shaft 106, this arm being able to be driven in rotation simultaneously with the shaft 106 by a transmission 117, and at one end it carries a knife 118 extending between the internal wall of the tank 104 and an external face of the die 113.

The die 113 is formed by a cylindrical section of revolution with central passage, as is clearly illustrated in FIGS. 8 and 9, the height of this section corresponding to the height of the rollers 108-109, while in its thickness, this section comprises a plurality of radial passages 120 uniformly distributed over the circumference and over the height. Each of the above-mentioned radial passages has, from the inside of the cylindrical section first (FIG. 9), a frustoconical section 120A which is extended by a cylindrical section 120B opening onto the outer wall.

As an order of magnitude, the cylindrical sections are advantageously provided with a diameter of 12 mm, while the largest base of the frustoconical section is provided with a diameter of 15 mm.

The orifice 105 of the press is in communication with a cooling apparatus 125 comprising an external air intake 126 and an outlet 127, the internal structure of the apparatus comprising a baffling.

At the outlet of the cooler, the sticks fall into a conventional elevator 140 with buckets, capable of discharging them into a storage hopper 141 constituting the last link in the chain.

The process of transforming household waste with an installation as described above can be analyzed as follows: the starting of the fan 47 serving the two cyclones placed in parallel 46 and 65 respectively creates a suction in the pipes 44 , 64, while depression

5

> 0

15

20

25

30

35

40

45

50

55

60

65

5

620,606

relative is also created in the lower part of the first cyclone 46 by the suction exerted from the second cyclone by the conduit 64 and the crusher 50; household waste, as collected, can then be discharged into the hopper 10, from where it falls by gravity - after opening the drawer 11 - into the shredder 12.

The purpose of passing the waste through the shredder is to open up the plastic bags, cardboard boxes and the like, containing household waste, without, however, spraying bottles, flasks and other glass objects.

The waste is then, by gravity, admitted inside the inclined screen 36 in which it is sorted and disposed of in three directions, namely:

The waste of medium density and having a reduced bulk pass through the perforations of the sieve and fall into the deflector 35 and, from there, into a suitable receptacle R;

waste having a high density and bulk preventing its passage through the perforations of the sieve is discharged at the lowest end of the screen, through passage 41, from where they fall by gravity into the bypass 45 of conduit 44 and, from there, advantageously in another receptacle RI.

As for low density waste, it is extracted from the screen by suction under the effect of cyclone 46 and admitted into the crusher 50.

It is noted here that, in this technique of conveying waste by pneumatic means, the difficulty lies in the separation of the air and the transported waste, separation which is usually obtained by a lock disposed at the base of the cyclone.

However, in the case under consideration, the provision of a lock at the base of the cyclone cannot be envisaged because the waste, not yet ground, such as in particular rags, twines, ropes, clothing and other similar products, would prevent a correct operation by entering and remaining blocked between the blades and the rotor constituting a lock.

This difficulty is solved according to the invention thanks to the arrangement of the knife mill 50 at the base of the first cyclone 46 and to the establishment of a relative vacuum through said mill from the entry of the second cyclone 65 by the connecting duct 64.

The crusher 50 thus simultaneously fulfills the role of a transfer lock for the separated materials in the first cyclone and that of a means for grinding these materials, the transfer of which to the second cyclone is ensured by the vacuum operated through the conduit 64.

In fact, only waste of relatively low density reaches the crusher 50, excluding glass articles, stones, ceramics, and other heavy parts (irons, plowshares, small motors, etc.), since these heavy objects were eliminated during their passage through the screen.

The waste passing through the crusher is reduced to particles and conveyed to the magnetic separator 80 through the lock 67. It will be noted that at this stage, it is possible to have a conventional lock at the base of the second cyclone 65, given that the waste presented at the lock is reduced to the state of particles which may certainly still contain metallic elements of small dimensions; the role of the magnetic separator 80 is to further extract these metallic elements remaining mixed with the particles insofar as they contain iron or other ferromagnetic metals.

The particles are admitted into the separator 80 by the rotor 73 of the lock 67 whose compartments c are loaded when they are in line with the cyclone 65 and are emptied by gravity in the separator when they are plumb with the access opening 82 of the magnetic separator.

Thus transferred to the separator, the metallic elements stick to the drum 85 under the effect of the magnetic sector 89, then are released above the conduit 90 when, as a result of the rotation of the drum, they are no longer subjected to the attraction of the magnetic sector, while the remaining particles are directed towards the conduit 91 opening into the mixer 95 in which said particles are vigorously stirred.

At this stage, it is advantageously added to the particles located in the mixer of the carbonate of lime located in a storage hopper 110 via a volumetric distributor (not shown).

The purpose of this incorporation is to transform the hydrochloric acid released during incineration by plastics based on chlorides (PVC) into salt; the amount of lime carbonate thus added may be of the order of 3 to 5%, for example, of the weight of granules produced.

From the mixer 95, the particles fall into the press 101 inside which the particles are transformed into granules by agglomeration.

In the press, the waste particles are taken up by the rollers 108-109 and extruded through the die 113.

According to a preferred embodiment, although not limiting, the die has a thickness of 100 mm and the radial passages 120 formed in the latter are provided with the following dimensions: the frustoconical section 120A and the cylindrical section 120B of revolution are of lengths substantially equal, or about fifty millimeters.

In this press, the mechanical work imposed by the rollers on the particles and subsequently the transformation, by compression of the latter into an agglomerated product, leads to a rise in temperature, so that the product leaves the die at a temperature of order of 80 ° C. This rise in temperature has the advantage of ensuring the destruction of pathogenic germs present in the waste.

The product leaving the die 113 is cut into sticks by the rotary vertical knife 118; this knife is driven in rotation at a determined circumferential speed, and it is moved away from the external surface of the die, so as to allow sticks to be obtained by breaking of the agglomerated product leaving the die, these sticks being able to have a length between 10 and 20 mm.

The rods obtained which appear in the form of cylindrical sections of revolution (FIG. 10) fall by gravity onto the bottom of the casing 104 of the press, from where they are led to the outlet 105 by the scraper arm 116 and, from there, in the cooler 125 where an air circulation brings the sticks to room temperature, at the same time as it exerts on them a drying effect.

After passing through the cooler, the sticks fall into the bucket elevator 140, the upper end of which is located in line with a conventional storage hopper with air circulation in which the granules are stored.

The transfer means installed, on the one hand, between the screen and the crusher and, on the other hand, between the crusher and the magnetic separator, could be conceived in the form of conveyor belts or chains with buckets, possibly enclosed in casings waterproof.

5

10

15

20

25

30

35

40

45

50

55

60

R

2 sheets of drawings

Claims (13)

620,606 1. Installation for transforming household waste into a combustible product by treating this waste in apparatus capable, on the one hand, of selecting combustible waste and, on the other hand, of transforming combustible waste into a unitary combustible product, characterized in that it comprises, from upstream to downstream - the upstream being a location where household waste is brought as collected, and the downstream being a location where the combustible product obtained is stored - a shredder equipped to break open packaging containing household waste, a screen to select waste according to their respective density, a grinder capable of reducing the waste thus selected into particles, a press to transform, by agglomeration and extrusion, the particles into granules. 2. Installation according to claim 1, characterized in that it comprises, between the screen and the press, a pneumatic handling device comprising two cyclones successively crossed by the selected waste in the screen, and having their chimneys connected in parallel to the 'Aspiration of a common fan, the passage of waste from the first to the second cyclone takes place through the crusher. 2 3. Installation according to claim 2, characterized in that the crusher is of the drum and knife type and lock form at the base of the first cyclone. 4. Installation according to claim 2, characterized in that a magnetic separator is arranged at the base of the second cyclone for the extraction of metallic residues from the particles obtained. 5. Installation according to any one of the preceding claims, characterized in that it comprises, between the magnetic separator and the press, a mixer in association with a silo housing an additional product capable of leading to the production of a compound non-volatile. 6. Installation according to one of claims 2 to 5, characterized in that the first cyclone is connected to the screen by a tube which comprises at its free end a rod with longitudinal opening, this rod which is inserted substantially in the axis of the screen being intended to aspirate low density waste, while a bypass extending said tubing is capable of discharging waste having a high density, waste having a medium density being discharged by a deflector placed opposite an opening in the screen housing. 7. Installation according to any one of the preceding claims, characterized in that the screen of the perforated drum type has an axis of rotation inclined relative to a horizontal plane. 8. Installation according to claim 1, characterized in that the shredder comprises two parallel rotors placed one beside the other on the horizontal, each of the rotors being formed by an Archimedes screw with removable knives arranged at the periphery, at least one of the rotors being mounted movable relative to the other. 9. Installation according to claim 1, characterized in that the press comprises, in a housing, a fixed die in the form of an annular crown and, inside this die, at least two pressure rollers, while a knife is adapted to move along the periphery of this die. 10. Installation according to claim 9, characterized in that the die includes a plurality of regularly spaced radial passages both on the height of the annular ring and on the periphery. 11. Installation according to any one of claims 9 or 10, characterized in that the radial passages have, along their respective axes, a section with frustoconical surface, extended by a section with cylindrical surface, the large base of the section with frustoconical surface leading to the inner wall of the die. 12. Installation according to claim 11, characterized in that the cylindrical and frustoconical sections formed in the thickness of the die are of equal lengths. 13. Installation according to claim 9, characterized in that the rotary knife is adapted to pass in an annular recess formed, on the one hand, by the outer wall of the die and, on the other hand, by the press housing , this knife being able to cut the product continuously leaving the die, in granules or sticks.