FR2498737A1 - COMBINED OVEN FOR THE COMBUSTION AND MERGER OF SOLID, PASTY AND LIQUID WASTE - Google Patents

Abstract

A pivotable drum (2) is equipped at the front with a burner (3) for liquid waste materials and at the rear with a tiltable charging device (4) for solid waste materials and waste materials filled in casks (14). The drum (2) is closed off at the rear by a fixed housing (13) surrounding the charging device (4). The rear drum end (2c) having a gas-outlet orifice (24) projects through a hood-like gas-inlet connection (23) of a fixed post-combustion chamber (5). The drum casing (2d) is stepped in such a way that a refractory lining (10), cooled from outside by means of water-spraying nozzles (11), of the semi-cylindrical drum bottom part (2b) is thinner by the amount of the drum-step depth than a refractory lining (9) of the semi-cylindrical drum top part (2a). The waste materials undergo pyrolysis as a result of the rocking movement of the drum, the pyrolysis gases flowing into the post-combustion chamber (2) through the gas-outlet orifice (24). At a particularly high combustion rate of the waste materials, the combustion air is blown through combustion-chamber nozzles (26) instead of through the drum burner (3). This achieves a shift of the combustion process into the post-combustion chamber (5), a temperature drop in the drum (2) and a slowing of the pyrolysis of the combustible material. As a result of an emptying pivoting of the drum through 180 DEG , the combustion residues melted by means of drum burners (3) are discharged discontinuously through the gas-outlet orifice (24).

Description

 The present invention relates to a combined oven for the combustion and melting of solid, pasty and liquid waste which comprises, as a support for the fuel, a drum furnished with a refractory material which, while being mounted on rollers for turning author of a longitudinal axis horizontal or inclined, can be subjected by a drive to a weight movement author of this axis to circulate the fuel, a feed device for solid waste being provided on one of the front sides of the drum which connects in the lower rear end zone with a vertical combustion chamber with fixed position.

 In a known known oven of this type and used exclusively for the combustion of waste, the continuous supply of waste to the flower takes place using a device which is provided on the front face before reaching a higher level. and having a feed opening, of the drum which performs a pendulum movement, while the open rear end of the drum fitted with a refractory material opens onto a vertical and fixed pest-c chamber @ which is produced by a mason @erie with refractory materials.One or more rows of nozzles for the introduction of combustion air are provided at the upper part of the drum cover, being in the middle position of its weight movement, and in the vertical median zone of the drum, being distributed over at least part of the length of the latter's envelope (@revet CH 440,526).

 There is also known a combined oven for the combustion and melting of waste of all kinds, in particular household waste, in which a support for the fuel having the shape of a trough as well as a weir edge for the evacuation of the slag. in fusion, is placed in a bowl with a horizontal or inclined longitudinal axis and which is incorporated in the front part of the oven. The bowl is mounted to pivot about its longitudinal axis and the preheated combustion air enriched with oxygen is blown into the oven feyer by means of nozzles provided in the upper wall of the front part of the oven and directed from above in direction of the trough (patent CH 411.198).

 These known ovens which are exclusively for combustion or for combined combustion and fusion of waste have the disadvantage that the various devices connected after the furnace such as boilers heated by waste heat, dust collectors and the suction drafting installation, receive an irregular quantity of smoke gas varying greatly in raisen from the rate of cembustion differs from waste of various kinds which has an unfavorable effect on heat recovery devices (heated boilers by waste heat) designed for constant thermal efficiency. Variations in the quantity of funée gas emitted are also undesirable for the other devices connected to the outlet of the flower and which must be carried out taking into account the emission of maximum smoke.

The object of the present invention is to overcome the drawbacks listed by creating a combined oven of the above type for the combustion and melting of waste which, despite the different combustion speeds resulting from the combustion behavior of waste of different nature, for example, of their calorific capacity, their moisture content and non-combustible materials, makes it possible to obtain during the operation of the flower, an amount of smoke gas remaining practically constant so that the positive devices brewed after the oven such as boilers, gas washers and the suction draft installation, are also subject to a uniform load,
These problems are solved in accordance with the invention by a combined melting and curing furnace which is characterized in that it has:
a) a feed device disposed outside the rear end wall of the drum having a feed opening, and mounted to pivot forward for the introduction into the furnace of charges such as solid waste and waste contained in drums;
b) a burner for liquid waste which is arranged coaxially with the axis of the drum on a sleeve connected to the front end of the drum;
c) a post-combustion chamber which has at its base a gas inlet pipe whose inlet opening communicates permanently with a gas outlet opening provided in the upper part of the drum, during the pendulum movement of this last;
d) refractory masonry and insulation of the upper part of the drum and of the burner sleeve mentioned under b);
@) a lining of the lower part of the drum by means of a refractory ceramic material as well as fixed nozzles provided outside the drum to spray water on the side wall of the latter;
t) a granulation tank filled with water, above which the opening set with gas mounted under c) can be pivoted from its central position by a 180 ° retation of the drum in order to evacuate the latter discontinuously molten combustion residues.

 Thanks to these characteristics, the devices connected after the furnace are traversed by a stream of burnt gases, the volume of which remains constant, which allows the use of devices for the treatment of flue gases whose dimensions are smaller than those of the devices provided. for conventional ovens which reduces their cost price and allows better yields to be obtained, in particular from the boiler heated by waste heat.

 Various other characteristics of the invention will also emerge from the detailed description which follows.

 Some highlights of the object of the invention are shown, by way of non-illustrative example, in the accompanying drawing.

 Fig. 1 shows, in vertical longitudinal section along the line I-I of FIG. 2, a combined combustion and melting furnace according to the invention.

 Fig. 2 shows the oven of fig. 1 in vertical cross section along line II-II of FIG. 1.

 The combined combustion and melting furnace 1 r shown in fig. 1 and intended for the combustion of salt, pasty and liquid waste, consists essentially of a drum 2 performing a pendulum movement during the operation of the oven and which present on its front side a burner 3 for liquid waste and on its rear side a feed device 4, mounted to pivot, for solid waste and pasty waste found in drums. The drum 2 communicates by its rear end with a vertical and stationary pest-combnstion chamber 5 and it can be pivoted from its media position above a granulation tank 6 filled with water by a retation of 180 to allow evacuation discontinuous molten combustion residues. The tamb @ ur 2 and the post-combustion chamber 5 constitute the main elements of the combined combustion and melting furnace 1.

 In the embodiment shown, the drum 2 whose longitudinal axis A2 is inclined rearward relative to the horizontal is mounted to rotate on rollers 7, 7a, and can perform by means of a control not shown a pendulum movement around this axis Â2 to circulate the fuel inside the drum 2. The pivot angle α of the pendulum movement of the drum 2 is for example 90 so that the drum 2 pivots by an angle ss of 45 on either side of its median position in which it is shown in fig. 1. The drive of the drum 2, which must be as simple as possible, is preferably carried out by means of a traction cable controlled hydraulically or pneumatically.

 On its front end and more haunts the drum 2 carries, coaxial to its longitudinal axis A2, a sleeve 8. A burner 3 for liquid waste such as solvents, used oils or water-oil mixtures is also mounted coaxially by with respect to the axis A2 on the front wall of the sleeve 8 while being sealed relative to the latter. The combustion air is also blown into the drum 2 by the burner 3. The body of the burner 3 which in the example shown is lied to slide on a straight guide 3b by means of rollers 3a, can be brought into the rear end position shown in mixed lines in fig. 1 so as to allow axial adjustment of the burner 3.

 The upper part 2a of the drum 2 as well as the sleeve 8 of the burner 3 accompanying the weight movement of the drum are coated and insulated immediately inside of a refractory material 9, while the lower and semi-cylindrical part 2b of the drum has a covering refractory 10 which is of a thickness substantially less than that of the coating 9 (see fig. 2) and which is cooled on its outer side by water conveyed by spray nozzles 11. Thanks to the lining 10 cooled by the with water it closes during the opening of the oven 1 and during the melting phase a hardened slag film on the groomed refractory surface which prevents destruction of the lining 10 by the liquid slag. A steel sheet envelope 2d surrounds the drum 2 and the sleeve 8 of the burner 3.

 The passage between the refractory lining 9 of the drum 2 and the lining 10 of substantially smaller thickness, is formed by a step (2s in fig. 2) of the cylindrical casing 2d of the drum provided externally on the circumference of the latter. , the somicylindrical lower part 2b therefore having an outside diameter which is appreciably smaller than that of the upper part 2a also somi-cylindrical of the drum which clearly emerges from FIG. 2.Because this step is not provided inside the drum 2 but outside the outer envelope 2d, despite the differences in the thickness of the walls of the drum 2, a perfectly cylindrical hearth F2 is obtained, and symmetrical about the longitudinal axis A2 of the drum 2 (see fig. 2).

 So that the drum 2 can in addition to the weight movement of 90 also perform from time to time a rotation of 180 for the discontinuous evacuation of the combustion residues in the granulation tank 6, a support 2e somi-cylindrical and shaped circle sector whose outer diameter corresponds to the outer diameter 2f of the upper part 2a of the drum, is provided on the lower semi-cylindrical part 2b of the latter. Therefore the drum 2 moves during its rotation of 180 teu first with the outer diameter 2f of the support 2e connected loosely, but preferably in a removable manner to the drum, and then with the outer diameter of its upper part s @ semi-cylindrical 2a, on the reuleaux of supp @ rt 7a as shown in fig. 2.

 The pivoting feed device 4 is lined to pivot on horizontal axes 13 externally dispersed relative to the rear end shield 2c, provided with a contral feed opening 12, of the drum 2.

The feed device 4 can therefore be pivoted forward 90 in the direction of arrow R4 passing through the opening 12 as indicated by mixed lines 4 'in FIG. 1. The container-type supply device 4 is intended to collect and supply the drum 2 with auccessive loads of solid waste as well as waste housed in drums 14. For this purpose, the supply device 4 comprises a support plate 15 which can be slid like a piston because it is mounted on a rod 16 which is axially guided in a bushing 17 fixed to the bottom 4a of the supply device 4.When the supply device 4 is tilted inside the drum 2 the free lower end of the rod 16 described by pivoting upwards an arc of a circle along the arrow R16 of the rig. 1 towards the position of introduction 16 ′ of the load indicated in mixedget treaty in which the rod as well as the plate 15 can be pushed forward by a control rod 18 advancing axially which has the effect of pushing the barrel 14 located in front the tray 15 or the waste located in the feed device 4, inside the drum 2.

The rear end of the drum 2 is sealed in order to prevent the ingress of parasitic air by means of a housing 19 which also surrounds the supply device 4, the control rod 18 being guided to slide axially by a socket 20 sealingly mounted on the rear wall 19a of the shoemaker 19.

 The pest-combustion chamber 5 which is also coated inside with a refractory material 9 and the base 5a of which rests on a frame 21 produced using steel profiles communicates during the pendulum movement of the drum 2 with an outlet opening gas 24 provided in the upper part 2a of the drum 2 via the opening 22 of a lower gas supply pipe 23 of the post-combustion chamber and by a tight connection. For this purpose the pipe gas supply 23 from the post-combustion chamber 5 is widened downwards by two cheeks engaging from above around the drum 2, the two cheeks 25 having a cylindrical shape corresponding to the circumference of the drum 2. The two cheeks 25 are arranged one behind the other in the sounds of the longitudinal axis A2 of the drum 2 while delimiting between them an interval which corresponds to the internal diameter V of the gas supply opening 22 of the post-combustion chamber 3. The cylindrical enlarged lower part of the gas supply opening 22 is adapted as regards its diameter, its shape and its position to the diameter, to the shape and to the amplitude of pivoting of the outlet opening of gas 24 of drum 2 with pendulum movement.

 The nozzles 26 for the combustion air are arranged in the lower part of the post-combustion chamber 3 and connected to a common annular duct 27 for the combustion air to be introduced in order to allow, when it becomes necessary, to move the combustion of the drum 2 towards the post-combustion chamber 3. This particular feature of the nozzles 26 is explained in detail during the description of the operation of the oven. A burner 28 which can operate on oil or gas is also provided in the lower part of the post-combustion chamber 3 and serves to maintain the ignition of the smoke gases coming from the drum 2 and flowing in the post-combustion chamber 5. A gas outlet opening 3b from the post-combustion chamber 3 conducts the burnt gases from the furnace 1 into the device mounted downstream, for example a radiation cooler. A sheet metal casing 5c surrounds the masonry 9 of the pest-combustion chamber 3.

 A plunging duct 29, also called "plunging groove", is connected from above to the lower ends of the two cylindrical ends 25 of the inlet pipe 23 of the combustion chamber and slightly plunges into the water bath 6a of the tank. granulation with its free lower end 29a which prevents unwanted entry of parasitic cold air from below into the drum 2 and / or the post-combustion chamber 3.

Fig. 2 shows the practically sealed connection with respect to the outside between the oscillating opening 24 of the gas outlet of the pendulum 2 drum 2 and the gas inlet opening 22 of the stationary post-combustion chamber 5. The vertical longitudinal median plane of the furnace 1 is designated by E1 in FIG. 2. In fig. 2 only the front cheek of the two cylindrical cheeks 23 arranged one behind the other with respect to the axis A2 of the drum 2 is visible. The cheeks 25 constitute a lower extension to the gas inlet pipe 23 furnished with a refractory material 9 from the post-combustion chamber 5 and these cheeks 25 surround, like a hood, from above the upper somi-cylindrical part 2a of the drum 2. The plunger conduit 29 made of sheet steel is connected from below to the two cheeks 25, two upper and cylindrical marginal portions 29b of the plunger conduit 29 and whose FIG. 2 shows only the front marginal part 29b being adapted as regards their shape to the circumference P2 of the lower part @ omi-cylindrical 2b of the drum 2. As can be seen in FIG. 1 the semi-cylindrical lower part 2b of the drum 2 has on its circumference two projections 2g also somi-cylindrical, forming a sector of a circle and tooth the circumference
P2 has the same diameter as the semicylindrical upper part 2a of the drum 2 and which serve to make the upper part of the plenum duct 29 stagnant in order to prevent the penetration of the parasitic air.

 In fig. 2 the drum 2 is represented in the middle position of its pendulum movement, the pivot angle of which α is 90 in the example shown, the plane of the vertical axis E2 of the drum 2 coinciding alers with the vertical median longitudinal plane E1 of the oven 1.

The gas outlet opening 24 of the drum 2 is delimited on either side by two flat and oblique surfaces 30, 31 which are arranged one by one to the other at an angle α of 90 whose painted S is located in the plane of the vertical axis 12 of the drum 2 and below the axis A2 of the latter. These two oblique surfaces 30, 31 provide the passage necessary for the gas outlet opening 24 of the drum 2 in the refractory lining 9 of the upper part 2a of the drum.

 The semi-cylindrical lower part 2b of the drum which forms, with the semi-cylindrical upper part 2a of the latter, two steps 2s situated in the plane of the horizontal axis H2 of the drum 2 and which are surrounded by a sheet metal envelope 2d steel similarly to the upper part 2a and steps 2 @, is formed essentially by the semi-cylindrical layer and cooled by the water spray nozzles (11 in fig. 1) of the refractory lining 10. The layer 10 is then substantially thinner than the wall of the upper part 2a of the drum coated with the refractory material 9, in the example shown the thickness of the layer 10 representing only one third of the thickness of the wall of the upper part 2a.

 Lersque the drum 2 leaves during its pendulum movement whose pivot angle a is 90 ', the median weight shown in fig. 2 to pivot by an angle ss of 45 to the left in the left end position, the oblique surface 30, located on the right in FIG. 2, from the gas outlet opening 24, also pivots in an upper and vertical end-of-travel position as indicated in FIG. 2 in mixed lines 30a and lersque the drum 2 leaves the middle weight to pivot by an angle ss of 45 towards the right in its right end of travel weight, the oblique surface of the left 31 also swings up in its weight of upper and vertical limit switch 31a indicated by mixed lines The two surfaces 30, 31 of the gas-set opening 24 of the drum 2 being placed in their end-of-vortical heart position, are alers in alignment with the inner surfaces 22a and 22b delimiting the opening 22 of the gas inlet pipe 23 of the pest-combustion chamber 5. The gas inlet opening 22 of the post-combustion chamber 5 has a rectangular section, the side of which is more long extends transversely to the median longitudinal plane E1 of the flower 1 and is adapted to the width of the gas outlet opening 24 of the drum 2 and the pivot angle α of 90 thereof. It can thus be seen that the gas outlet opening 24 accompanying the pendular movement of the drum 2 does not obstruct the flow of pyrelyse gases preventing from the drum 2 in the pest-combustion chamber 3 when the drum 2 and thereby also its gas outlet opening 24 are in the two end-of-travel positions during the pendulum motion. During the pendular movement of the drum 2, its gas outlet opening 24 consequently communicates with the gas inlet opening 22 of the stationary post-combustion chamber 3.

 With a view to the discontinuous evacuation of the combustion residues in fusion in the granulation tank 6 filled with water, the drum 2 occasionally performs a single pivoting of 180 from its central position E1 to then return to this position median. Since the plunger duct 29 is, in the example shown, offset to the left relative to the vertical median longitudinal plane E1 of the furnace 1, the drum emptying movement 2 @ 'also performs to the left in the sounds of arrow R2. The position occupied at the end of the pivoting of the 180 emptying of the drum 2 by the two delimiting surfaces 30, 31 of the gas outlet opening 24 directed towards the bottom, is also indicated in FIG. 2 in dashed lines 30 ′, 31 ′. It is then obvious that the offset position of the plunger duct 29 and the asymmetrical section of its upper part allow the complete evacuation of the liquid combustion residues located inside the drum 2.

 The operation of the combined combustion and melting furnace is explained below by describing the combustion phase and the melting phase.

1. Combustion phase
During this phase, solid waste as well as solid or pasty waste found in barrels are introduced by successive charges into the oven 1 by means of the tilting feed device 4. The combustion air is blown in by the burner 3 into the front sleeve 8 of the drum 2. The waste is stirred intensely as a result of the pendulum movement of 90 of the drum 2.

 When waste whose rapid combustion is introduced into the furnace l, the combustion air is no longer supplied by the burner 3 but entirely or partially by the nozzles 26 in the post-combustion chamber 5. The waste is located inside the drum 2 are then subjected to a pyrolysis, that is to say that they are disintegrated under an elevated temperature or thermally decomposed, a process also called "dry distillation." The pyrolysis gases then leave the drum 2 in motion through the upper gas outlet opening 24 and and flow into the post-embedding chamber 5 where they are ignited.

By this process it becomes possible to move the combustion process of the drum 2 into the post-combustion chamber 3 where only heat is created. As a result, the temperature inside the drum 2 is lowered and the pyrolysis of the fuel is slowed down. As a result, the devices mounted downstream of the furnace 1, such as boilers heated by waste heat, purifiers of flue gases and the suction draft installation are charged with a uniform flue gas stream. In the event that these measures are insufficient to create a constant flue gas stream it is possible to inject additional water in the drum 2 as cooling fluid, by means of the burner 3. The burner 28 with the aid of which fuel oil or used oil is injected into the post-combustion chamber 5 serves to maintain ignition of the pyrolysis gases.

 2.

Merger phase
As soon as the lower part 2a of the drum 2 is filled with combustion residues originating from the preceding combustion phases or possibly with barrels 14 to the point that it is no longer possible to add other waste, it is injected using the burner 3, solvents or other liquid fuels such as oils or water / oil mixtures and these fuels are burned inside the drum 2. By the high temperatures thus created the solid combustion residues are melted and then evacuated by the pivoting 180 of the drum 2 so that they fall into the granulation tank 6 filled with water passing through the burnt gas outlet opening 24, projecting downwards, from the drum 2.

Claims (8)

 1 - Combined oven for the combustion and melting of solid, pasty and liquid waste which comprises as a support for the fuel a drum lined with a refractory material which all being mounted on rollers to rotate around a longitudinal axis horizontal or inclined, can be subjected by a pendulum movement around this axis to circulate the fuel, a feed device for solid waste being provided on one of the front sides of the drum which communicates in the area of its lower rear end with a vertical post-combustion chamber with a fixed station, characterized in that it has:  a) a feed device (4) disposed externally to the rear end wall (2c) of the drum (2) having a feed opening (12), and mounted to pivot forward for insertion into the furnace (1) of charges such as solid waste and waste contained in the trusses (14);  b) a burner (3) which is afraid of liquid waste and which is arranged coaxially with the axis (A2) of the drum on a sleeve (8) connected to the front end of the drum (2);  c) a post-combustion chamber (5) which has at its base a gas inlet pipe (23) whose inlet opening (22) communicates in pormanence with a gas outlet opening (24) provided in the upper part of the drum (2), laying down the pendulum movement of the latter;  d) a refractory masonry (9) and an insulation of the upper part (2z) of the drum (2) and of the burner sleeve (8) mentioned under b);  ) a lining (10) of the lower part (2b) of the drum (2) by means of a refractory ceramic material as well as fixed nozzles (11) arranged outside the drum (2) for spraying water on the side wall of the latter;  f) a granulation tank (6) filled with water above which the gas outlet opening (24) mentioned under c) can be pivoted from its central position by a rotation of 180 of the drum to evacuate from the latter , discontinuously, the combustion residues melted.  2 - Oven according to claim 1, characterized in that the drum (2) of substantially cylindrical farm has on its outer circumference (P2) a step (2s) extending in the direction of the axis (A2) of the drum ( 2) and in that the refractory material layer (10) of the lower part (2b) of the drum (2) has a thickness which is reduced by the height of the step (2s) relative to the thickness of the coating (9) in refractory material do the upper part (2a) of the drum (2) which, therefore, has a cylindrical feyer (F2) and coaxial with the axis (A2) of the drum (2).  3 - Oven according to claim 2, characterized in that the step (2s) of the drum (2) is placed in the axial plane (H2) of the latter and that the upper and lower parts (2a, 2b) are made to present a somi-cylindrical shape with different outside diameters.  4 - Oven according to claim 2, characterized in that the lower part (Zb) of the drum (2) is provided with a support (2e) in firm circle sector for the support and rolling rollers (7a) of the drum (2), the outside diameter (2f) of the suppert (2e) lies @ corresponding to the outside diameter of the upper part (2a) of the drum (2).  5 - Oven according to claim 1, characterized in that the burner 3 for liquid waste is axially adjustable.  6 - Oven according to claim 1, characterized in that the supply device (4) produced in the form of a container and which can pivot about a horizontal axis (13) has a support plate (15) which can be moved to the like a piston and being equipped with a push rod (16) which is guided to slide axially by a bushing (17) mounted in the bottom 4a of the device (4) and in that the rear end of the drum ( 2) is closed by an envelope (19) which also encloses the supply device (4) and a control rod (18) for the supply device (4) is guided to smooth axially in the rear wall (19a ).  7 - Oven according to claim 1, characterized in that the gas inlet pipe (5a) of the post-combustion chamber (5) widens in the form of a cover thanks to two cheeks (25) engaging by the top around the drum (2), the two cheeks (2S) having a cylindrical shape in accordance with the circumference (P2) of the drum while being distant from each other in the sounds of the axis (A2) of the drum (2) so as to delimit between them the internal width (W) of the gas inlet opening of the post-combustion chamber (5) and in that the upper part of a plunger duct (29) associated with a granulation tank (6) is connected from below to the two cheeks (25).  8 - Oven according to claim 1, characterized in that the post-combustion chamber (5) has at its base (5a) nozzles (26) for combustion air and a burner (28) for fuel oil heating, gas or liquid waste.