FR2560425A1 - INSTALLATION FOR TREATING A MIXTURE OF SUBSTANCES AND METHOD TO BE IMPLEMENTED WITH SUCH AN INSTALLATION - Google Patents

Abstract

THE INSTALLATION IS APPLIED AND THE PROCESS IS IMPLEMENTED IN THE FIELD OF WASTE INCINERATION. AT THE INSTALLATION IS AN OVEN 2 WHICH INCLUDES AN EXTERNAL WALL 14, A BOTTOM 15 WITH AN EXHAUST OPENING 5, AN INTERNAL BODY 16, 29, 30, 32, A COVER 26, A BURNER 3 INSIDE THE A BELL 29 BELONGING TO THE INTERNAL BODY, A DEVICE 1, 4 TO PROVIDE THE SUBSTANCES TO BE TREATED, MEANS 30, 31, 37 AND 25, 26 TO PROVIDE FUEL AIR, A DISTRIBUTOR SHIRT 17, A SUPPLY SHIRT 19 , AND MEANS 45, 46, 47 TO ROTATE THESE SHIRTS. THE SUPPLY CHAMBER 19 IS LOCATED INSIDE THE ANNULAR SPACE BETWEEN THE INTERNAL BODY 16, 29, 30, 32 AND THE DISPENSER SHIRT 17. THE COVER 26 COMPLETELY CLOSES THIS SPACE. THE INSTALLATION IS USED IN PARTICULAR TO TREAT A MIXTURE OF COMBUSTIBLE AND INCOMBUSTIBLE WASTE MATERIALS, IN PARTICULAR RADIO-ACTIVE WASTE PRODUCTS.

Description

Installation for treating a mixture of substances and process for

work with a

such an installation.

  The invention relates to an installation for treating a mixture of substances, with an incineration furnace which consists of - an external wall which comprises - an external envelope and - a bottom with an evacuation opening, - a internal body which descends to a certain distance from the bottom, delimits, together with the outer envelope, an annular space, and internally forms a bell, the space between the lower edge of the bell and the bottom forming a combustion chamber a cover which closes the annular space at the top, a burner which is arranged inside the top of the bell of the internal body, a device for supplying the substances or materials to be treated, which opens at the top in the annular space, means for supplying combustion air to the furnace, dispensing jacket which is located inside the annular space, level with the place where the supply device opens and below, and

  means for rotating said dispensing jacket.

  Installations of this kind are used in particular for treating a mixture of combustible and non-combustible waste materials, including radioactive waste products. The mixture falls in the form of a cone with a natural slope on the bottom of the oven. This cone with natural slope forms the bottom of the combustion chamber -2 - effective and protects the bottom of the oven. On the surface of this naturally sloped cone, incombustible materials melt to leave the molten furnace through the opening in

the bottom.

  An installation of this kind is known from

FR-A-2 187 100.

  In this known installation, the lid which closes the annular space at the top has a discharge opening through which part of the combustion gases escape at the top of the annular space. Moisture is thus removed from the products

  waste before they fall on the bottom of the oven.

  The subsequent treatment of the combustion gases is thus

made more difficult.

  The purpose of the invention is in particular to eliminate this drawback and to offer an installation of the kind defined above, whose incineration furnace has a good efficiency without having to evacuate part of the gases from

  combustion via the annular space.

  In the aforementioned known installation, the distribution of the substances to be treated inside the annular space is effected by the rotary distributor jacket, but the downward movement of the substances supplied is caused exclusively by gravity. The substances to be treated can therefore be distributed unevenly on the bottom, which can disadvantageously influence the operation of the installation. A second object of the invention is to provide an installation of the kind defined above in which the substances to be treated are provided more regularly on

the bottom of the incineration furnace.

  To achieve the aforementioned purposes, the incineration furnace is further provided with a feed jacket, which is located inside the annular space between the inner body and the dispensing jacket, descends to below the dispensing jacket, and is provided, in the vicinity of the lower edge of the inner body, with feeding spoons, and means for rotating said feed jacket, and the lid closes completely the annular space at the top. In a particular embodiment of the invention, the feed jacket is provided on its outer surface below the dispensing jacket, but above the feed spoons, spoons

of settlement.

  In an advantageous embodiment of the invention, the means for rotating the dispenser jacket, rotate the latter at a speed

  in the range of zero to fifty revolutions per hour.

  In a particularly useful embodiment of the invention, the means for rotating the feed jacket, rotate it at a speed

  in the range of a quarter to nine rounds per hour.

  In a particularly useful embodiment of the invention, the incineration furnace comprises

means to cool the bottom.

  Said means can be formed by a wind box fixed against the bottom face of the bottom and / or

  by cooling channels for a cooling liquid

  which are also fixed against the underside

the bottom.

  The invention also relates to a method that can be implemented by means of the installation described above. The invention thus relates to a method for treating a mixture of combustible and non-combustible substances, which comprises providing said mixture at the top in a closed space at the top, which consists of a mainly vertical annular upper part and a lower part mainly horizontal connection thereto, said mixture filling said horizontal portion at least to the level of the vertical portion and forming, within said horizontal portion, a cone with a natural slope which opens at the bottom on an opening made in the part horizontal, a combustion thus occurring inside the horizontal part and

  the complete evacuation taking place through the opening.

  An object of the invention is to provide a new method of this kind with a better distribution of

substances to be treated.

  For this purpose, a first series of rotating means distribute the mixture at the top within the vertical portion, over the entire periphery, and other rotating means tamp the mixture at a lower level, within said portion. vertically, and bring the

mix in the horizontal part.

  Other details and advantages of the invention

  will emerge from the following description of an installation

  for the treatment of a mixture of substances, and a method to be implemented with such an installation

  according to the invention; this description is only

  given as an example and does not limit the invention;

  reference numerals refer to the accompanying drawings.

  FIG. 1 is a schematic longitudinal sectional view of an installation for the treatment of a

  mixture of substances according to the invention.

  FIG. 2 is a schematic longitudinal sectional view of the incineration furnace of the installation represented in FIG. 1, but on a larger scale

and with a little more detail.

  In both figures, the same figures of

  reference relate to the same elements.

  The installation shown in Figure 1 comprises a feed tube 1 which opens into the upper end of an incineration furnace 2 which is provided at the top of a main burner 3. Said main burner 3 can provide fuel and pressurized air in the incineration furnace 2, such that said furnace can operate under pressure, for example in the range of 2 kPa. The incineration furnace 2 can however also operate under a slight depression, for example in the range of -2 kPa. Using a screw conveyor 4, the substances to be treated, in particular radioactive waste,

  are sent to the incineration furnace 2 via

  1. The substances to be treated will generally consist of a mixture of combustible and non-combustible materials. Although the substances to be treated can essentially be made up of non-combustible materials, the installation will usually be used for a mixture of 10% by weight, preferably 80% to 90% by weight, of combustible substances, and thus of 90 to 10% by weight, preferably 20 to 10% by weight, of incombustible substances. Fusion agents can be added

to the substances to be treated.

  The incineration furnace 2 has in its bottom an opening 5 for substances which are evolved or formed during heating or combustion. By

  Therefore, the fusion product of

  fuels, combustion gases and combustion residues of combustible substances, and volatile substances released by heating, are removed by

  via said opening.

  The incineration furnace 2 opens by opening on an auxiliary combustion chamber 6. Said chamber is made of refractory metal and lined internally with refractory material. Liquid combustion residues are separated from gaseous residues

  inside the auxiliary combustion chamber 6.

  Said auxiliary combustion chamber 6 opens to the bottom in the air-tight aqueous bed of a granulator 8, by means of a water-cooled double-walled connecting pipe 7. The aqueous bed has a temperature of the order of 80 C. The liquid combustion residues coagulate in the aqueous bed and form granules which are removed periodically from the aqueous bed, by means of a conveyor chain device not shown in FIG. 1 for the sake of clarity, through openings that can be sealed airtight. On one side, an auxiliary burner 9 with its own combustion chamber 10, is connected to the combustion chamber 6. Said auxiliary burner 9 maintains the temperature inside the combustion chamber

  auxiliary 6 in the range of 1300 to 1600 C.

  On the opposite side, a post-combustion chamber -7-11 of refractory metal, is connected to the auxiliary combustion chamber 6. The inner face of the chamber 11 is coated with a refractory material. The post-combustion chamber 11 opens into an outlet orifice 12. Through this orifice, the combustion gases escape from the installation, after which they

  are cooled, possibly washed, and filtered.

  The walls of the auxiliary combustion chamber 6 and the afterburner chamber 11 are of twin design and cooling air

crosses them.

  Secondary air is supplied by

  ducts 13 between the combustion chamber

  auxiliary 6 and the afterburner 11.

  As is particularly clear from Figure 2, the incineration furnace 2 comprises an outer wall constituted by a cylindrical outer envelope 14 and a funnel bottom 15, an inner cylindrical wall 16 fixedly mounted co-axially therein ,

  which is part of an internal body, a folder distribu-

  trice 17 which is rotatably mounted between the outer shell 14 and the inner wall 16 and carries a multiplicity of outwardly directed dispensing spoons 18, and a feed jacket 19 which is rotatably mounted between the dispensing jacket 17 and the inner wall 16, and carries a multiplicity of helical packing spoons 20 and a multiplicity of spoons

Power supply 21.

  The outer casing 14 is made of metal. The bottom 15 is made of refractory metal. The opening 5 is located in the center of said bottom 15 and is surrounded by a cooling duct 22 in which circulates cooling water. Said cooling duct 22 is

surrounded by a ring 23.

  Against the bottom face of the bottom 15 are formed cooling ducts 24 through which a cooling liquid is pumped, and wind boxes 25 in which air is blown. The innermost parts of the incineration furnace 2, namely the inner wall 16, the dispensing jacket 17 and the feed jacket 19, are suspended from a removable cover 26 which rests on

the outer envelope 14.

  The inner wall 16 is secured to the lid

  26 and is therefore fixed with respect to the outer casing 14.

  Between the upper edge of the rotary feed jacket 19 and the fixed inner wall 16 is a water seal 27. A water seal 27 is also present between the upper edge of the rotary distributor sleeve 17, and the sleeve of food

  19 and the outer shell 14, respectively.

  The inner body further comprises the inner wall. 16, a conical bell which is mounted thereon, which is constituted by a refractory lining 29. On its smallest upper end, the bell 29 carries a box

  wind 30 which is supplied with combustion air by means of

  middle of the pipe 31. On the lower end more

  wide of the bell 29 is mounted a cooling duct

  32 in which is pumped a coolant

  is lying. The main sheller 3 mounted in the center of the closed upper end of the bell 29 is supplied with liquid fuel via the pipe 33. The air for the sheller 3 is supplied via the pipe 34. In conduits 35 circulates a

  coolant to cool the burner 3.

  Air for combustion is provided with an overpressure of 0.2 to 5 kPa relative to the pressure inside the furnace, to the pipe 31 which feeds via the wind boot 30, pipes 37 which open into the bell 29. Air for combustion is also provided with an overpressure between 0.2 and 5 kPa with respect to the pressure inside the furnace, wind boots 25 which open by of the

openings 36 in the oven.

  The combustion air is used simultaneously to cool the oven, in particular the bottom 15, and

  it is preheated before reaching the inside of the oven.

  Inspection tubes 38 and 39 pass through

the walls of the bell 29.

  The substances to be treated are provided by the screw 4 driven by a motor not shown, at the top in the annular space 41 between the outer casing 14

  and the dispensing jacket 17. The dispensing spoons

  18 which are attached to the lower end of the dispensing jacket 17, are at the height of the opening of the feed tube 1 and distribute the substances to be treated uniformly on the periphery of said annular space. The dispenser liner 17 is rotated at a speed of twenty revolutions / hour by

  a motor not shown in Figure 2.

  Said motor drives a transmission mechanism, corresponding to the transmission mechanism defined below for driving the feed jacket 19. A ring gear 46 is thus set in motion; said ring gear 46 is fixed by

  compared to the dispensing folder 17.

- 10 -

  An engine not shown in Figure 2 entrains the transmission mechanism 45 which in turn drives a ring gear 47. The latter is

  fixed relative to the feed jacket 19.

  The speed of rotation of the feed jacket 19 is three revolutions / hour. In contrast to the dispensing jacket 17, the feed jacket 19 descends to the lower edge of the inner wall 16. The feed jacket 19 is located

  furthermore immediately adjacent to said inner wall 16.

  Dispensing spoons 20 are spirally distributed on the part located below the dispensing jacket 17, on the outer face of the feed jacket 19. Said spoons have a shape such that they exert during the rotation of the liner. supply 19, a downward pressure on the substances that are in the space 42 between said portion of the feed jacket 19 and the outer casing 14. Said settlement spoons 20 repel

  therefore uniformly down the waste materials.

  Supply spoons 21 are attached to the lower end of the feed jacket 19 and push the substances to be burned out of the space 42, in the combustion space 43 itself, between

the bottom 15 and the bell 29.

  Said substances form on said bottom 15, a cone or funnel with a natural slope, whose opening

connects to the opening 5.

  The main burner 3 starts the combustion of the waste materials within the combustion space 43 and maintains as necessary this combustion. The refractory walls of the bell 29 reflect during combustion, the

- 11 -

  thermal radiation to the cone with natural slope formed by the materials on the bottom 15. Therefore is reached within the combustion space, a temperature which is a function of the fuel flow that is burned by the burner 3, and flow and composition

  waste materials that are supplied by the screw 4.

  This temperature is in the range of 1300 to 1600 C. In any case, this temperature must be above the melting point of incombustible waste materials, so that the upper layer

  cone with a natural slope reaches this melting point.

  At the upper surface of the naturally sloping cone are formed droplets of liquid which flow downwards through the opening 5 and, as already described above, are transformed into solid granules.

in the granulator 8.

  The waste materials themselves and their liquid upper layer in the combustion space 43 isolate the bottom 15 from the heat, so that the temperature of this bottom, also thanks to the fact that said bottom is cooled on its underside ,born

hardly rises above 70 C.

  The combustion air that is provided by the openings 36 in the bottom 15, in the space 43, passes through the burning materials. Thus, four mutually connecting zones are formed inside the cone with a natural slope on the bottom 15, which consist respectively of a lower layer where the substances are dried by combustion air, a pyrolysis layer or a pre-heating layer. combustion o thermally unstable waste materials are broken by heat from the overlying layers and from which the gases formed are entrained with the combustion air, a layer

- 12 -

  Combustible components and pyrolytic gases react with oxygen in the air, and a molten layer where incombustible waste materials and ashes are melted into a basic slag. The combustion gases can leave the furnace only through the opening 5, that is to say through the liquid layer on the surface of the cone with natural slope, which layer acts as a filter and retains a large amount of substance. Because of this flow of flue gases, the waste materials burn with

a turbulent flame.

  The separation of the liquid and gaseous combustion residues takes place, as already described, inside the

auxiliary combustion chamber 6.

  After the combustion gases have been separated from the liquid combustion residues, the combustion

  gas is complete inside the post-chamber

combustion 11.

  During operation of the furnace, nitrogen under a slight overpressure is supplied by the feed tube 1 to the combustion furnace. This prevents combustible or explosive gases from rising

spaces 42 or 41.

  The invention is in no way limited to the embodiment described above and in the context of the patent application, numerous modifications can be made to the embodiment described, in particular as regards the shape, the composition, arrangement and number of components that are used to carry out the invention. The dispenser liner and the feed jacket need not necessarily have the

- 13 -

  aforementioned speeds. These shirts need not necessarily turn in the same direction. Wide ranges of advantageous speeds are indicated above.

- 14 -

Claims (17)

  1. Installation for treating a mixture of substances, with an incineration furnace (2) which comprises: - an outer wall which is formed by an external envelope (14) and - a bottom (15) with an opening of evacuation (5), - an inner body (16,29,30,32) which descends to a certain distance from the bottom (15), delimits together with the outer casing (14), an annular space (41-42 ), and internally forms a bell (29), the space between the lower edge of the bell (29) and the bottom (15) forming a combustion chamber (43), - a lid (26) which closes at the top. annular space (41-42)   - a burner (3) which is arranged inside the top of the bell (29) of the inner body (16,29,30,32), - a device (1,4) for supplying the substances to be treated, which emerges at the top in the annular space (41, 42), - means (30, 31, 37 and 25, 36) for supplying combustion air to the oven (2), - a dispensing jacket (17) which located inside the annular space (41), at the point where the delivery device (1,4) opens and below, and - means (46) for rotating said dispensing jacket (17). ), characterized in that - the incineration furnace (2) is further provided with: - a feed jacket (19), which is located inside the annular spade - 15 -   between the inner body (16, 29, 30, 32) and the dispensing jacket (17), extends below the dispensing jacket (17), and is provided adjacent to the lower edge of the inner body (16, 29, 30,32), feeding spoons (21), and - means (45-47) for rotating said feed jacket (19), and - the lid (26) completely closing the annular space (41,42) at the top.   2. Installation according to claim 1, characterized in that the feed jacket (19) is provided below the dispensing jacket (17) but above the feed spoons (21), spoons   packing (20) on its outer face.   3. Installation according to one or the other   claims 1 and 2, characterized in that the shirt   dispenser (17) and the feed jacket (19) are rotatably suspended from the cover (26), a first water seal (27) is arranged between the upper edge of the dispensing jacket (17) and on the one hand , the outer casing (14) and, on the other hand, the feed jacket (19), and a second water seal (27) is located between the upper edge of the feed jacket (19) and the internal body (16,29,30,32).   4. Installation according to any one   claims 1-3, characterized in that the means   to rotate the dispenser sleeve (17), rotate it at a speed in the range of zero to fifty turns per hour.   5. Installation according to any of the   Claims 1-4, characterized in that the means for - 16 -   rotating the feed jacket (19), rotate it at a speed in the range of a quarter to nine turns per hour.   6. Installation according to any one   claims 1-5, characterized in that the body   internal (16, 29, 30, 32) includes a cylindrical inner wall (16) and a tapered refractory liner (29) mounted there.   7. Installation according to claim 6, characterized in that the means (30,31,37 and 25,36) for supplying combustion air to the oven (2), comprise a wind boot (30) which is mounted to the upper end of the bell (29) of the inner body (16,29,30,32), an air supply pipe (31) which opens onto said wind box (30) and at least one pipe (37). ) which connects the wind boot (30) to the inner side of the   bell (29) and passes through the refractory lining (29).   8. Installation according to any of the   claims 1-7, characterized in that the means   (30,31,37 and 25,36) for supplying combustion air to the oven (2) comprise at least one feed (25,36) which opens on the bottom (15).   9. Installation according to any one   Claims 1-8, characterized in that the oven   of incineration (2) comprises means (24,25) for bottom cooling (15).   10. Installation according to claim 9,   characterized in that the means (24,25) for the re-   cooling of the bottom (15) of the outer wall (14, 15) comprise channels for a coolant,   which are fixed against the underside of the bottom (15).   11. Installation according to one or the other   claims 9 and 10, characterized in that the means - 17 -   (24, 25) for cooling the bottom (15) of the outer wall (14, 15) comprise a wind box (25) which is   fixed against the underside of the bottom (15).   12. Installation according to claims 8   and 11, characterized in that the wind boot (25) is part of the means (30, 31, 37 and 25, 36) for supplying combustion air to the furnace (2) and communicates by means of   openings (36) with the interior of the oven (2).   13. Process for the treatment of a mixture of combustible and non-combustible substances, according to which said mixture is supplied at the top to a closed space at the top consisting of a mainly vertical annular upper part and a mainly horizontal lower part connected thereto. said mixture filling the horizontal part at least to the level of the vertical part and forming inside said horizontal part, a cone with a natural slope which opens at the bottom in an opening made in the horizontal part, a combustion thus occurring at the interior of the horizontal part and the complete evacuation taking place through the opening, characterized in that a first series of rotating means distributes the mixture at the top inside the vertical part, over the entire periphery, and other rotating means tamp the mixture at a lower level within said portion   vertical and drive the mixture to the horizontal part.   14. Process according to Claim 13, characterized in that the combustion gases leaving   the horizontal part through the opening, are filtered.   15. Process according to one or other   Claims 13 and 14, characterized in that a mixture   from 10 to 90% by weight of combustible substances and   10% by weight of incombustible substances is treated. - 18 -   16. Process according to claim 15, characterized in that a mixture of 80 to 90% by weight of combustible substances and 20 to 10% by weight of   incombustible substances is treated.   17. Process according to any one of   Claims 13-16, characterized in that the combustion   inside the horizontal part takes place at a   temperature in the range of 1300 to 1600 C.