FR2761458A1 - LIQUID, PASTY AND SOLID WASTE INCINERATOR - Google Patents

Abstract

The invention concerns an incinerator for liquid, pasty and solid waste, characterised by its architecture with operating stages comprising, from the top downwards: a fourth level (N4) comprising means (5, 11) for introducing waste and means for maintaining, inside said fourth level (N4) constituting the incinerator top part, a temperature less than the flammability temperature of the waste to be incinerated; a third level (N3) arranged for ensuring said waste combustion at high temperature; a second level (N2) arranged for completing solid waste combustion; a first level (N1) comprising means (25, 26) for receiving and evacuating ashes.

Description

Liquid, pasty and solid waste incinerator
The present invention relates to an incinerator of liquid, pasty and solid waste, such as industrial waste, agricultural waste, hospital waste, medical care waste and household waste.

 Current waste incinerators of the aforementioned type are most often produced in the form of large and complex industrial units comprising specialized ovens or boilers for waste disposal according to their nature: liquid, pasty or solid. Such waste incineration plants require large spaces and considerable investment for their construction and operation. Their design and volumes make them poorly integrated into the urban or rural environment.

 An object of the invention is to provide a multipurpose incinerator that complies with legislative and regulatory standards and allows the elimination of all kinds of waste (liquids, pastes and solids), while being simple in construction, operation and maintenance.

According to the invention, this objective is achieved thanks to a remarkable incinerator by an architecture with function stages comprising successively and from top to bottom:
- A fourth level arranged for the reception of waste or fuel and for maintaining a low temperature (lower than the combustion temperature of the waste to be incinerated, for example of the order of 1500 to 200 C);
- A third level arranged to ensure combustion at high temperature of the waste (for example of the order of 600 "C to 1200"C);
- A second level arranged to complete the combustion of solid products (in which, for example, a temperature of the order of 800 "to 900 C is maintained);
- and a first level arranged for the reception and the evacuation of the ashes.

 This multi-stage incinerator allows the destruction of liquid, pasty and solid waste with very low calorific value and which can contain up to 70% humidity.

It has a faster destructive capacity than in a conventional incinerator and still has, in particular, the following advantages:
- simple and quick start-up,
- reduced energy consumption during the ignition time of the waste;
- a great autonomy of non-stop walking,
- high operational safety;
- total combustion of the waste, the ultimate residues being reduced to the state of dust;
- simplified maintenance;
- compliance with anti-pollution standards in force, with gases released into the atmosphere, harmless, odorless and invisible.

 - a better possibility of integration into the urban or rural landscape.

The aims, characteristics and advantages above, and others still, will emerge more clearly from the description which follows and from the appended drawings in which:
Figure 1 is a front view, schematic in vertical section, of the functional stage incinerator according to the invention.

 Figure 2 is a schematic view, in vertical section and on a larger scale, of the upper stage of the incinerator.

 Figure 3 is a top view and schematic of the top of the incinerator.

 Figure 4 is a detail view showing one of the cooling devices of the upper part of the internal side wall of the device.

 Figure 5 is a top view of the liquid or pasty waste distribution device installed in the upper part of the device.

 Figure 6 is an axial sectional view and schematic of the third level of the incinerator.

 Figure 7 is a detail view, on a larger scale and in section, of a retarder device installed in the lower part of the third level of the device.

 Figure 8 is a sectional view along line 8-8 of Figure 1.

 Figure 9 is a sectional view along line 9-9 of Figure 1.

 Figure 10 is a sectional view along line 10-10 of Figure 1.

 Figure 11 is a cross-sectional view illustrating the profile of the charging grid arranged in the lower part of the third stage, above the retarder and the ignition burner.

 FIG. 12 is a detail view, on a larger scale, of FIG. 11.

 Figure 13 is a schematic view in median section of the lower part of the device comprising the second and first levels thereof.

 Figure 14 is a plan view of Figure 13.

 Reference is made to said drawings to describe an interesting, although in no way limiting, embodiment of the waste incinerator according to the invention.

 This incinerator comprises an outer vertical wall or envelope 1 and an inner vertical wall or body 2, between which an annular space is reserved; these walls, as well as the various essential component parts of the device described below, being advantageously made of refractory stainless steel. The walls 1 and 2 may have a circular cross section, as illustrated, but they could also have a square, rectangular or other horizontal section.

According to a characteristic arrangement of the invention, the incinerator is arranged so as to present function stages comprising successively, from top to bottom:
- A fourth level N4 comprising means for introducing waste and means making it possible to maintain, inside said fourth level constituting the upper part of the apparatus of the incinerator, a temperature below the flammability temperature of the waste to be incinerated;
- a third level N3 arranged to ensure the high temperature combustion of the waste;
a second level N2 arranged to complete the combustion of the solid products;
- and a first level N1 arranged for the reception and evacuation of the ashes.

 The arrangement of these four stages is described below in succession.

 The upper end of the fourth level N4, that is to say the upper end of the apparatus, is closed. The upper end of the annular smoke collector C1 constituted by the space formed between the side walls 1 and 2 is closed by a horizontal wall 3 in the form of a circular crown, while the upper end of the upper chamber C2 delimited by the inner wall 2 is closed by a dome-shaped wall 4.

 In the upper wall 4 is provided at least one inlet and, preferably, a plurality of inlets 5 (five inlets according to the example illustrated), for the introduction of liquid or pasty waste into the incinerator. These inlets which can have different and adjustable flow rates, due to their allocation (introduction of liquid or pasty products) are mainly constituted by pipes passing through the wall 4 and provided with solenoid valves or other shutters for adjusting the inlet of the products.

 The pipes 5 for the arrival of solid or pasty waste pass through the upper wall or cap 4 and open into the chamber C2, above a distribution device 6 making it possible to disperse said liquid or pasty waste flowing from said pipes. The inlet pipes 5 are for example assembled in the central part of the upper cap 4 and they open out above a dispersing device 6 constituted by a convex circular sheet (in the form of a cone or spherical cap). To promote this dispersion, the disperser is provided with corrugations 6a at its periphery (Figure 5).

 The upper wall or cap 4 of the device is also provided with cooling means advantageously constituted by at least one inlet and, preferably, by a plurality of cooling water inlets 7. According to the example illustrated, L ' device is provided with four cooling water inlets 7 spaced 90 "apart and arranged near the periphery of said cap.

 These cooling water inlets are, for example, constituted by pipes passing through the upper cap 4 and equipped with solenoid valves or other shutters allowing their flow to be adjusted. The internal end of these pipes, provided with an appropriate nozzle (spray nozzle or the like), is directed towards the internal surface 2a of the internal side wall 2, so that the jet of cooling water is projected against this surface (Figure 4).

The cooling means 7 have a double function:
- on the one hand, avoid igniting liquid or pasty waste before it arrives in the incinerator's fireplace; and,
- on the other hand, prevent an excessive rise in temperature in the upper stage of the device, which would cause damage to the equipment fitted to the upper cap 4 of the incinerator.

 The cooling water introduced into the upper part of the incinerator is not necessarily pure water, it can be, in fact, water pumped into the settling tank of a washing device for smoke, which eliminates the sludge produced by this device, by incinerating it.

 The method and the cooling means 7 make it possible to maintain, inside the level N4, a temperature below the combustion temperature of the waste to be incinerated, which is for example between 1500 and 200 "C.

 In applications where the implementation of the cooling means described above would not make it possible to maintain a temperature below 200 "C in the upper part of the device, provision is made to cool said upper part (upper cap 4, upper wall 3 and side wall 1), by means of a water jacket 29, with inlet 29a and outlet 29b allowing circulation of the cooling water.

 The upper cap 4 is also provided with a central water inlet 8 which is constituted by an axial pipe passing through said upper cap and also the dispersing device 6.

 This central water inlet has the function of allowing the rapid extinction of the appliance hearth, when it is necessary to stop the operation of the incinerator.

 The upper cap 4 can be provided, externally, with gussets 9 allowing the attachment of a lifting device sling.

Laterally, the upper stage N4 of the device is provided
- On the one hand, a smoke outlet 10 shaped to be able to be connected, in any known manner, to a smoke duct, by means of a smoke washing system; and,
- on the other hand, an inlet 11 for the introduction of solid waste.

 The smoke outlet 10 communicates with the upper part of the smoke collector C1, while the solid waste inlet 11 opens into the chamber C2, this inlet comprising, for example, a cylinder passing through the annular smoke collector C1 and communicating with room C2.

 Solid waste is, for example, brought to inlet 11, by means of a worm conveyor, itself supplied by a crusher, after sorting said waste.

 In the smoke collector C1 and at the level of the lower part of the chamber C2, a horizontal partition 12 is installed in the form of a crown and provided with holes 13 arranged around the inner wall 2. These holes 13 are slightly spaced and their diameter is barely less than the distance between the outer 1 and inner 2 walls.

 The perforated partition 12-13 serves to disperse the heat around the internal chamber C2, the mixture of hot air and burnt gases being unable to rush directly towards the flue, this mixture being distributed uniformly through the holes 13 in all points of the upper part of the smoke collector C1.

 This arrangement also makes it possible to avoid the flashback.

 The upper stage of the apparatus is equipped, externally or internally, with various devices known per se and necessary for the perfect functioning of said apparatus, such as electro-valves for opening and closing and adjusting the flow rate, temperature sensors, regulators, pollutant control sensors, safety valves, etc.

 In the upper part N4 of the incinerator can be provided, laterally, an opening provided with an airlock for the introduction of contaminated waste, so that the latter cannot be heated with release of toxic vapors before the complete closure of said opening .

 The third stage N3 comprises a central combustion chamber C3 delimited by the internal side wall 2 and communicating freely with the chamber C2. The central combustion chamber C3 is surrounded by the lower part of the smoke collector C1 which communicates with the upper part thereof, through the holes 13 that the horizontal wall 12 presents.

The lower part of the high temperature combustion chamber C3 communicates with the smoke collector C1, through a retarder assembly 14 installed at said lower part, which aims to slow the escape of the air / combustion gas mixture in it imposing a chicane course in the lower part of the room
C3. This retarder assembly can advantageously be constituted by a plurality of perforated cylindrical belts 14a, 14b, 14c, 14d, arranged concentrically around the axis of the chamber C3 and spaced from one another. The perforations 14a ', 14b', 14c ', 14d' of these belts have diameters which decrease from the center outwards, as shown in Figure 7.

 The smaller diameter perforations 14d ′ of the outer perforated belt 14d open into the lower part of the smoke collector C1.

 At least one burner 15 is installed at the height of the retarder assembly. This burner passes through the set of perforated belts 14a, 14b, 14c, 14d, so that its combustion head is located in the space delimited by the internal perforated belt 14a of said set of belts.

 The burner 15 can be gaseous fuel or liquid fuel. It is used for starting ignition of the incinerator.

 It allows the combustion to start at the different desired temperatures and stops at the programmed temperature.

 Above the retarder assembly is mounted an inclined grid 16 consisting of bars, one or more of which can be cooled by circulation of water or other cooling fluid.

 Advantageously, this grid consists of tubular bars 16a, 16A and bars 16b having a very open V profile, preferably arranged alternately. The tubular bars 16A, 16a preferably have a square section and they are oriented so as to have two upper faces 16a 'inversely inclined.

The inclined faces 16a ′ of the central bar 16A have an overhanging lateral part 16a "ending above one of the wings of the neighboring bar 16b (FIG. 12). In this way, there is no vertical passage between the central bar 16A and the two V-shaped bars placed on either side of the latter. The ignition burner 15 is disposed below the central bar assembly 16b-16A-16b and is therefore protected by this assembly
Vertical passages 30 are provided between the other bars 16a, 16b of the grid 16.

 The tubular bars 16A, 16a are connected, respectively, to an inlet pipe and to an outlet pipe (not shown) allowing the circulation of a cooling fluid (water or other) inside said bars.

 It is observed that during the operation of the incinerator, a layer of ash is deposited on the inclined surfaces 16b 'of the V-shaped bars 16b, this layer of ash constituting a protection of said bars against the effects of the high temperature maintained in the chamber C3 .

 The upper central part of the grate 16 is disposed above the burner 15 as indicated above, while its lower part leads to an outlet hatch 17 fitted to the side wall of the incinerator. This grid has many functions.

- It retains liquid or pasty waste which has not been burned when it enters the high temperature hearth, so as to allow their combustion;
- It retains solid waste for the time necessary for their calcination, while allowing the waste of calcined waste in the underlying stage N2 to fall;
- It allows the routing of refractory waste towards the outlet hatch 17;
- it protects the burner 15.

 In the lower part of the combustion chamber, opens at least one compressed air injector 18. Preferably, the incinerator is equipped with a plurality of injectors and, for example, four injectors 18 spaced 90, opening out above the retarder assembly 14.

 These injectors are connected to a compressor or other blower system and allow the introduction of compressed air into the fireplace. Their number and flow rate depend on the capacity of the incinerator.

 This injection of compressed air is used to regulate the temperature of the hearth, that is to say to maintain the temperature necessary to destroy certain molecules, that is, depending on the nature of the waste to be eliminated, a temperature between 600 "and 1200" vs.

 To allow total oxidation and complete destruction of the waste, high heating temperatures can be reached and modulated, depending on the nature of the said waste, by injecting a variable quantity of air, in particular into the high temperature fireplace C3, using the air inlet solenoid valves of different diameters.

 The air / burned waste gas mixture burned, is pushed down under the pressure of the compressed air injected into the combustion chamber C3, and escapes into the annular smoke collector C1 under the suction effect created by the chimney, passing through the perforations of the set of perforated belts 14a, 14b, 14c, 14d, which make it possible to slow down its circulation by lengthening its path.

Thanks to the implementation of this incineration process, certain apyrious molecules are stationed in the lower part of the high temperature upper hearth, for the time necessary (four seconds or more, at 1200 C) to their complete destruction.

 The incinerator can be equipped, at the level of the compressed air injectors 18, with injectors (not shown) of gaseous waste which can thus ignite instantly, as soon as they enter the upper hearth C3.

 The side wall 2 of the combustion chamber C3 is cooled by means of a water jacket disposed around the lower part of said wall.

For this purpose, an annular chamber C4 with at least one water inlet 19 and at least one water outlet 20, surrounds the lower part of the wall 2, this chamber being delimited, externally, by a wall 21 arranged, concentrically , around the wall 2 and at a distance from it,
The annular space formed between these walls being closed at its upper and lower ends.

Laterally and at a level above the grid 16,
The incinerator is equipped with a door 22 for manual loading. This large door is intended for the introduction of bulky solid waste whose reduction into fragments of reduced size, by means of a grinder, is not possible or very difficult. It is pivotally mounted around a lower horizontal axis a-a ', by means of hinges (not shown).

 The second stage of the incinerator consists of a set of superimposed grids 23 comprising at least two superimposed grids 23a, 23b.

 This set of superimposed grids 23 is advantageously of the kind described in the document WO 93119324, that is to say an assembly whose grids are formed by flat bars 23a ′, 23b ′ inclined around their longitudinal axis, the flat bars 23a 'of one of the grids having an inverse inclination to that of the flat bars 23b' of the other.

 The purpose of this set of grids is to retain partially calcined solid waste until it is completely incinerated.

 This arrangement makes it possible to maintain a temperature of the order of 800 "C to 900 C in the lower hearth constituted by the second stage of the incinerator.

 The first stage N1 is arranged for the reception and the evacuation of the ashes.

 This stage comprises a movable ashtray 25 in the form of a funnel, arranged below the set of grates 23 and at the bottom of which is installed a device for extracting the ashes (ultimate residues), for example constituted by a screw without end of extraction 26 associated with a suction system making it possible to convey the ashes to a storage silo.

 The ashtray 25 is, for example, equipped with rollers 28 on two of its opposite sides, these rollers resting on parallel raceways 27 rigidly secured to the lower part of the carcass of the device.

 Cold air inlets 24 are provided in the side wall of the appliance, around the ash tank, which makes it possible to cool the ashes and to oppose the descent of the air introduced to the upper part (3rd floor) of the appliance.

 A smoke washing device (not shown) can advantageously be installed between the smoke outlet 11 and the smoke duct. The washing effluents are collected in a settling tank and, as indicated above, these effluents can be pumped and introduced into the upper part of the incinerator to participate in the cooling of the upper stage of the latter, in addition, this process eliminates sludge from the smoke washing device.

The chimney (not shown) into which the smoke washing device opens, is equipped with a blower (turbine) allowing the ejection of the fumes at a speed of the order of 12 m / s, while
creating a depression at the smoke outlet 11, necessary for good
operation of the incinerator.

Claims (16)

1. - Incinerator of liquid, pasty and solid waste, characterized by its architecture with functional stages comprising, from top to bottom: - a fourth level (N4) comprising means (5,11) for introducing waste and means allowing to maintain, inside said fourth level (N4) constituting the upper part of the incinerator, a temperature below the flammability temperature of the waste to be incinerated; - a third level (N3) arranged to ensure the high temperature combustion of this waste; - a second level (N2) arranged to complete the combustion of solid products; and, - a first level (Ni) comprising means (25, 26) for receiving and removing the ashes. 2. - Incinerator according to claim 1, characterized in that the means making it possible to maintain, inside the upper level (N4) of said incinerator, a temperature below the flammability temperature of the waste to be incinerated, consist of a or several devices (7) for spraying cooling water against the internal wall (2) of said upper level (N4). 3. - Incinerator according to one of claims 1 or 2, characterized in that the inlets (5) of liquid or pasty waste are disposed on the cover cap (4) of said incinerator and open above a device for distribution (6) of said liquid or pasty waste. 4. - Incinerator according to claim 3, characterized in that the inlets (5) of liquid or pasty waste are collected on the central portion of the cover cap (4) and in that the distribution device (6) consists by a convex circular disperser, preferably having corrugations (6a) at its periphery. 5. - Incinerator according to any one of claims 1 to 3, characterized in that the third level (N3) comprises: - a high temperature combustion chamber (C3) disposed below the waste introduction chamber (C2) and communicating freely with the latter, this chamber (C3) being delimited by a side wall (2), - a charging grid (16) disposed at the bottom of said chamber (C3); - And one or more compressed air injectors (18) opening into the lower part of said chamber. 6. - Incinerator according to any one of claims 1, 2, 3 and 5, characterized in that it comprises an annular smoke collector (C1) disposed around the waste introduction chamber (C2) and around the high temperature combustion chamber (C3). 7. - Incinerator according to claim 6, characterized in that the high temperature combustion chamber (C3) communicates with the smoke collector (C1) through a retarder device (14) installed at the bottom of said chamber. 8. - Incinerator according to claim 7, characterized in that the retarder device (14) consists of a plurality of cylindrical perforated belts (14a, 14b, 14c, 14d) arranged concentrically and spaced from each other. 9. -Incinerator according to claim 8, characterized in that the cylindrical perforated belts (14a, 14b, 14c, 14d) have perforations (14a ', 14b', 14c ', 14d') whose diameters are decreasing from the center outward. 10. - Incinerator according to any one of claims 1 to 9, characterized in that at least one burner (15) is installed in the lower part of the high temperature incineration chamber for the start-up ignition of said incinerator , this burner (15) preferably opening into the space delimited by the internal grid (14a) of the set of grids (14). 11. - Incinerator according to one of claims 5 or 10, characterized in that the charging grid (16) has an inclined position in the direction of a hatch (17) for evacuating refractory waste. 12. - Incinerator according to one of claims 5 or 11, characterized in that the charging grid comprises tubular bars (16a) cooled by internal circulation of water and bars (16b) provided with a V profile. 13. - Incinerator according to any one of claims 5,11 or 12, characterized in that the bars (16a, 16b) of the charge grid (16) have at least one flat inclined surface (16a ', 16b') waste reception. 14. - Incinerator according to any one of claims 1 to 13, characterized in that its second level (N2) consists of a set of superimposed grids (23). 15. - Incinerator according to claim 14, characterized in that the grids (23a, 23b) of the set of superimposed grids (23) are constituted by flat bars (23a ', 23b') inclined around their longitudinal axis, the flat bars (23a ') of one of the grids having an inverse inclination to that of the flat bars (23b') of the other grid. 16. - Incinerator according to any one of claims 1 to 15, characterized in that a smoke washing device is installed between the smoke outlet (11) of said incinerator and the smoke duct.