Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/50—Control or safety arrangements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B30/00—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber
  • F23B30/02—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts
  • F23B30/06—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel supporting surfaces that are specially adapted for advancing fuel through the combustion zone
  • F23B30/08—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel supporting surfaces that are specially adapted for advancing fuel through the combustion zone with fuel-supporting surfaces that move through the combustion zone, e.g. with chain grates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B30/00—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber
  • F23B30/02—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts
  • F23B30/06—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel supporting surfaces that are specially adapted for advancing fuel through the combustion zone
  • F23B30/10—Combustion apparatus with driven means for agitating the burning fuel; Combustion apparatus with driven means for advancing the burning fuel through the combustion chamber with movable, e.g. vibratable, fuel-supporting surfaces; with fuel-supporting surfaces that have movable parts with fuel supporting surfaces that are specially adapted for advancing fuel through the combustion zone with fuel-supporting surfaces having fuel advancing elements that are movable, but remain essentially in the same place, e.g. with rollers or reciprocating grate bars
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B60/00—Combustion apparatus in which the fuel burns essentially without moving
  • F23B60/02—Combustion apparatus in which the fuel burns essentially without moving with combustion air supplied through a grate
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/002—Incineration of waste; Incinerator constructions; Details, accessories or control therefor characterised by their grates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
  • F23G5/002—Incineration of waste; Incinerator constructions; Details, accessories or control therefor characterised by their grates
  • F23G5/004—Incineration of waste; Incinerator constructions; Details, accessories or control therefor characterised by their grates with endless travelling grates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
  • F23G7/10—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of field or garden waste or biomasses
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L1/00—Passages or apertures for delivering primary air for combustion 
  • F23L1/02—Passages or apertures for delivering primary air for combustion  by discharging the air below the fire
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L13/00—Construction of valves or dampers for controlling air supply or draught
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L3/00—Arrangements of valves or dampers before the fire
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
  • F23M9/00—Baffles or deflectors for air or combustion products; Flame shields
  • F23M9/02—Baffles or deflectors for air or combustion products; Flame shields in air inlets
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N5/00—Systems for controlling combustion
  • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
  • F23N5/08—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements
  • F23N5/082—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/08—Measuring temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2229/00—Flame sensors
  • F23N2229/20—Camera viewing

Definitions

• the present invention relates to a combustion installation.
• the invention relates in particular to combustion installations integrated into a boiler which transfers the heat released by combustion to a heat transfer fluid, generally water.
• the combustion plants concerned use, as fuels, household or industrial waste, hazardous waste, biomass or similar solid materials, which, more generally, corresponds to solid fuels, in particular inhomogeneous in time and space.
• solid fuels considered here typically form a material flow, the exact composition of which is both inhomogeneous at a given instant and liable to vary over time.
• the solid fuels are introduced into a combustion chamber in order to undergo combustion therein, called primary combustion, in the presence of air, called primary air, this primary combustion leading to the fact that, on the one hand, the the non-volatile part of the solid fuels is burned entirely, except for particulate unburnt particles, and, on the other hand, the volatile part of the solid fuels, released during the heating of the latter and the combustion of their non-volatile part, or partially burned.
• This primary combustion can in particular be carried out on a grate, which delimits the combustion chamber downwards and on which the solid fuels are loaded to undergo the primary combustion therein, while the primary air is admitted under the grate before passing through this last to enter the combustion chamber and thus reach the solid fuels.
• secondary air consisting of air and / or recirculated fumes
• the distribution of the primary air by the boxes can be adjusted according to the infrared radiation emitted by the layer formed by the solid fuels in the combustion chamber.
• This infrared radiation is measured by an infrared camera installed on the ceiling of the combustion chamber.
• this infrared camera does not provide information on the effective temperature of the primary combustion of solid fuels, but only provides a partial indication of the temperature at the surface of the solid fuels. the whole of the solid fuel layer, this partial indication being furthermore disturbed by particles and dust, present vertically between the solid fuel layer and the infrared camera.
• the pressure drop due to this layer is generally inhomogeneous, due to the system for depositing solid fuels on the grid, as well as the relative disparity in the kinetics of combustion of solid fuels and heterogeneities of solid fuels, both in size of their solid fragments and in composition and humidity, in particular for solid fuels of the waste or biomass type.
• This inhomogeneity of the pressure drop at the level of the grid has the consequence of favoring the passage of primary air in the least dense zones of the layer, in other words the zones having less solid fuels and therefore requiring in theory less primary air, to the detriment of the densest areas of the layer, in other words areas with more solid fuels and which in theory require more primary air. In the densest areas of the layer, primary combustion may be incomplete.
• the primary combustion may be pushed to excess so that the resulting ash may be in less quantity, or even fly away under the effect of the fire. speed of the air passing through the grid directly above these areas.
• Such untimely flights of ash can affect the equipment downstream of the combustion chamber and can also lead to the destruction of the grate because the latter is then deprived of the protection conferred by the thickness of the ash against direct radiation from the combustion chamber. primary combustion.
• GB 2,077,892 discloses a combustion plant for solid fuels.
• This combustion installation has three adjacent grids, which are separated two by two by refractory walls.
• Primary air is supplied to the installation's combustion chamber, being admitted under each of the three grilles.
• three independent channels are provided which are delimited by watertight partitions.
• the primary air is, at an upstream inlet, divided into three distinct air flows which, under the corresponding grid, flow to this grid independently of each other due to the separation carried out. through watertight bulkheads.
• the aim of the present invention is to provide a combustion installation which, without resorting to a group of boxes under the grate, improves the conditions for the admission of the primary air.
• the subject of the invention is a combustion installation, as defined in claim 1.
• the idea at the base of the invention is to keep a single primary air distribution volume under the grille, but to integrate specific aeraulic features in this volume capable of forcing the distribution of the primary air under the grid, without significantly affecting the size, in particular the vertical dimension, of this volume.
• the invention thus provides for subdividing the air inlet of a single chamber, to form therein streams of primary air, the flow rate of which is individually adjustable.
• the invention also makes it possible to act on the aeraulics of these primary air streams, thanks to dedicated internal arrangements of the single chamber, in order to send these primary air streams to respective regions of the grille. These arrangements are advantageously provided to prevent the accumulation of ash under the grate.
• the combustion installation according to the invention thus makes it possible to control the spatial and quantitative distribution of the primary air intake, thanks to compact and economical arrangements.
• the actuation of the flow rate regulators can be manual or automatically controlled.
• the corresponding control can advantageously be provided from measurements of the temperature of the primary combustion, carried out by pyrometers, as detailed below.
• FIG. 1 is a diagram of a combustion installation according to the invention
• FIG. 2 is a view on a larger scale of a box II of FIG. 1, illustrating a variant of the corresponding part of the combustion plant;
• FIG. 3 is a partial schematic section taken along the line III-III of FIG. 1.
• Figure 1 is shown a combustion installation 101 suitable for burning solid fuels C.
• the solid fuels C are in particular household or industrial waste, hazardous waste, biomass, or similar solid materials, that is to say, more generally, solids exhibiting heterogeneity. in size, composition and / or humidity, as mentioned in the introductory part of this document.
• the combustion plant 101 typically belongs to a boiler which makes it possible to produce water vapor by using the heat of the flue gases from the combustion plant.
• the combustion installation 101 comprises a combustion chamber 110 adapted so that the solid fuels C are introduced into it and burn there according to a primary combustion in the presence of air, called primary air P.
• the combustion chamber 110 is delimited laterally by:
• the combustion chamber 110 is designed to, once the solid fuels C are loaded therein, allow these solid fuels C to stay for a time necessary, typically several minutes, to carry out the primary combustion. During their primary combustion, the solid fuels C generate gases which, in the immediate vicinity of the solid fuels C, are referenced G in FIG. 1.
• the combustion chamber 110 is designed to channel these gases, up to their exit from the combustion chamber 110 from which escapes fumes F circulating in the boiler equipment, such as heat exchangers.
• the combustion chamber 110 is provided to admit therein a secondary air S, consisting of air and / or recirculated fumes.
• a secondary air S consisting of air and / or recirculated fumes.
• the admission of the secondary air S into the combustion chamber 110 is located vertically at a distance from the solid fuels C present in the combustion chamber, so that the aforementioned gases G are only generated by the gas.
• primary combustion of solid fuels C, without including secondary air S, while the mixture between these gases G and secondary air S is referenced GS in Figure 1 and forms the fumes F at the outlet of the combustion chamber 110
• the secondary air can thus be introduced in several vertical levels, as indicated in figure 1.
• the primary combustion leads to the fact that, on the one hand, the non-volatile part of the solid fuels C is completely burned, except for unburned particles fluidized in the gases G, and, on the other hand, the volatile part of the solid fuels, released during the heating of the latter and during the combustion of their non-volatile part, that is to say partially burnt, by forming the gases G.
• the secondary air S feeds a secondary combustion, namely the combustion of the gases G to form the gases GS, thus completely burning the volatile part of solid fuels C.
• the combustion chamber 110 comprises a grid 114 which delimits the bottom of the combustion chamber.
• This grate 114 is designed to support the solid fuels C inside the combustion chamber 110 so that, as illustrated in FIG. 1, these solid fuels form a bed which rests on the grate 114, extending from the rear wall 111 to the front wall 112.
• the bed is supplied with solid fuels to be burnt, for example by the outer chute 120, while, at the level of the front wall 112, the bed is supplied. evacuated, in particular by falling into the evacuation 121.
• the bed of solid fuels C is movable in a direction of advance Z in the combustion chamber 110.
• the direction of advance Z extends from the rear wall 111 to the front wall 112, while being parallel to the grid 114.
• the grid 114 may equally well be inclined with respect to a horizontal plane, as in FIG. 1, as well as s' extend in a horizontal plane.
• the grid 114 has two side edges, which are opposite to each other in a horizontal direction perpendicular to the direction of advance Z and which extend respectively along the two side walls 113 of the combustion chamber 110.
• the grate 114 may be provided inclined to allow the gravity drive of the bed and / or be provided movable to act on the drive of the bed, while being then animated with a movement allowing a slow displacement of the solid fuels from their point of arrival on the grate, where they are not yet burnt, to their outlet point of the grate, where they are completely burnt.
• various drive systems are known, such that, for example, the grid rotates like a conveyor belt, or the bars of the grid move alternately, etc.
• the embodiment of the grid 114 can also be linked to the device for introducing the solid fuels C into the combustion chamber.
• the solid fuels C can be introduced through another wall. of the combustion chamber, in particular through the front wall 112, the introduction device then being an external, mechanical and / or pneumatic injector, which is able to project the solid fuels into the combustion chamber, from the wall front to the region of the grille 114, abutting the rear wall 111.
• the primary air P is admitted under the grid and this grid 114 is designed to be passed from bottom to top by the primary air P to allow the latter to enter. in the combustion chamber 110 and thus reach the solid fuel bed C.
• the combustion installation 101 also comprises an intake device 130 making it possible to supply the combustion chamber 110 with the primary air P.
• the intake device 130 is, at least for its downstream outlet, arranged below the gate 114.
• the intake device 130 comprises a single box 131 having an air inlet 132 provided to be supplied with the primary air P.
• the air inlet 132 opens into a casing 133 of the box. 131, arranged below the grid 114.
• the air inlet 132 is divided into several subdivisions, which, in the example considered here, are three in number and which are respectively referenced 132.1, 132.2 and 132.3.
• Each of the subdivisions 132.1 to 132.3 connects a supply line 135, which carries the primary air P and which is common to the various subdivisions, to the casing 133, opening into the internal volume of this casing 133.
• the subdivisions 132.1 to 132.3 all open into a single and the same primary air distribution volume, which is arranged under the grille 114 and which is formed by the internal volume of the casing 133.
• the subdivisions 132.1 to 132.3 respectively transport primary air streams V1 , V2 and V3, which are distinct from each other. Each of these air streams V1 to V3 thus flows, in the corresponding subdivision 132.1 to 132.3, from the supply line 135 to the internal volume of the housing 133.
• each of the subdivisions 132.1 to 132.3 is provided with a flow rate adjustment member 134.1 to 134.3 making it possible to control the flow rate of the corresponding primary air stream V1 to V3.
• the embodiment of the flow adjustment members 134.1 to 134.3 is not restrictive of the invention.
• each of the flow adjustment members 134.1 to 134.3 comprises a register 136, which is arranged inside the corresponding subdivision 132.1 to 132.3 and which is designed to pivot on itself in order to to adjust the flow rate of the corresponding primary air stream V1 to V3.
• This register 136 is for example a butterfly register.
• FIG. 2 An alternative embodiment for the flow regulator 134.1 to 134.3 is illustrated in figure 2. More precisely, figure 2 shows an alternative embodiment for the flow regulator 134.1, it being understood that this form of alternative embodiment can be applied to the other flow regulators 134.2 and 134.3.
• the flow control member 134.1 comprises two flaps 138A and 138B, which are arranged symmetrically inside the subdivision 132.1, each being articulated with respect to this subdivision . By means of their articulated displacement relative to the subdivision 132.1, the flaps 138A and 138B move away from or approach one another, symmetrically with respect to each other, thus modifying the size of the flow section of subdivision 132.1, while keeping this flow section centered on the central axis of subdivision 132.1, as shown schematically in Figure 2.
• the symmetry of the arrangement and movement of the shutters 138A and 138 makes it possible to control the flow rate of the primary air stream V1 with a low pressure drop, in particular without significantly modifying the flow speed of the air stream V1 in the subdivision 132.1.
• the pressure drop is all the more limited as the flaps 138A and 138B are slightly inclined, typically at less than 45 °, relative to the flow axis of the air stream V1 in the subdivision 132.1 .
• maintaining the speed of the air streams V1, V2 and V3 in the box 130 allows a lower variation in the penetration of the air streams into the box, this penetration being proportional to the quantity of movement, that is to say to the product between the flow rate and the speed, and consequently makes it possible to more easily maintain the distribution of the air flows P1, P2 and P3, defined a little later, between the different zones Z1, Z2 and Z3, also defined a little further.
• the flow rate adjustment member 134.1 comprises an actuator 139, such as a cylinder, which is connected to the flaps 138A and 138B in an appropriate manner, for example by connecting rods, as illustrated. schematically in figure 2.
• the air inlet 132 extends substantially horizontally, by causing the primary air streams V1 to V3 to flow substantially horizontally in the subdivisions 132.1 to 132.3, until it thus emerges into the internal volume of the casing 133 by passing through this casing laterally.
• the casing 133 is not arranged in the vertical upward extension of the air inlet of the casing.
• the subdivisions 132.1 to 132.3 of the air inlet 132 are then advantageously arranged one above the other: in FIG. 1, the subdivision 132.1 is arranged above of subdivision 132.2 which is itself arranged above subdivision 132.3.
• the casing 133 is fitted internally to direct the primary air streams V1 to V3, leaving the air inlet 132, towards respective regions 114.1, 114.2 and 114.3 of the grid 114, which follow one another in the direction of advance Z.
• the internal volume of the casing 133 is provided with arrangements which make it possible to act on the flow primary air streams V1 to V3, once out of subdivisions 132.1 to 132.3, so that these primary air streams form, at the outlet of box 131, respective primary air streams P1, P2 and P3, which are sent, below the grid 114, respectively to the regions 114.1 to 114.3 of this grid.
• each of the regions 114.1 to 114.3 of the grate 114 are fixed in the combustion chamber 110, whatever the embodiment of the grate 114: thus, when the grate 114 is fixed in the combustion chamber 110, each of the regions 114.1 to 114.3 corresponds to a part of this grid, which is unchanged during the operation of the combustion installation 101; when the grate 114 is mobile, each of the regions 114.1 to 114.3 is, at each instant of the operation of the combustion plant 1, occupied by a part of the grate 114, this part being able to change region during the movement of the grate 114
• region 114.1 is, among regions 114.1 to 114.3, closest to rear wall 111 while region 114.3 is closest to front wall 112, this region 114.3 succeeding region 114.2 which itself follows the region 114.1 following the direction of advance Z.
• zone Z1 of solid fuel bed C rests on region 114.1 of gate 114
• area Z2 rests on region 114.2
• area Z3 rests on region 114.3 of gate 114.
• regions 114.1 through 114.3 of gate 114 areas Z1 through Z3 of bed solid fuels C are fixed in the combustion chamber 110.
• each of the zones Z1 to Z3 of the bed consists of a part of the solid fuels C and that, at a later instant in the operation of the combustion installation, each of the zones Z1 to Z3 of the bed is occupied by another part of the solid fuels C, at least partially different from the aforementioned part of these solid fuels C, of the made the displacement of the bed in the direction of advance Z.
• the solid fuels C progressively pass, in the combustion chamber 110, through the zone Z1 of the bed formed by these fuels C on the grid 114, then by zone Z2, and finally by zone Z3 of the bed.
• solid fuels C undergo the progressive effects of primary combustion, namely first their drying, then gasification for their volatile part and combustion for their non-volatile part, and finally a cooling and a combustion finish for their non-volatile part.
• the aforementioned internal arrangements of the box 101 comprise plane deflectors 137.1 and 137.2.
• Each deflector 137.1, 137.2 forms with the vertical an angle of between 0 and 20 °, which amounts to saying that each of the deflectors 137.1 and 137.2 extends either strictly vertically or at a slight inclination relative to the vertical.
• the deflectors 137.1 and 137.2 are arranged inside the casing 133 in a fixed manner or in a slightly movable manner by manual adjustment.
• this arrangement of the deflectors 137.1 and 137.2 has a somehowlic and practical advantages: on the one hand, the deflectors 137.1 and 137.2 can thus modify the direction of the air flows inside the casing 133, from the substantially horizontal flow direction for the primary air streams V1 to V3 to the substantially vertical flow direction for the primary air stream P1 to P3; on the other hand, the deflectors 137.1 and 137.2 prevent the accumulation of ash which falls on them from the grid 114. Furthermore, to act selectively on the various primary air streams V1 to V3, the deflectors 137.1 and 137.2 are arranged in a stepped manner: more precisely, the respective lower ends of the baffles 137.1 and 137.2 are stepped relative to each other.
• the lower end of the deflector 137.1 is located, vertically, substantially at the same level as the separation between the subdivisions 132.1 and 132.2 and, horizontally, in half of the internal volume of the casing 133, turned to the air inlet 132; as for the lower end of the deflector 137.2, it is located, vertically, substantially at the level of the separation between the subdivisions 132.2 and 132.3 and, horizontally, in half of the internal volume of the casing 133, opposite the air inlet 132.
• the specific features of the stepping of the lower ends of the deflectors 137.1 and 137.2 may differ from what has just been described in connection with the example of FIG. 1.
• this staging can be optimized by preliminary computations of computational fluid mechanics, by considering the combustion installation 101 in a nominal operating regime.
• the staging of the respective lower ends of the deflectors 137.1 and 137.2 is provided so that the deflectors 137.1 and 137.2 interact selectively on the primary air streams V1 to V3 to orient the latter respectively towards the corresponding regions 114.1 to 114.3 of the grille 114: in the example of FIG. 1, the primary air stream V1 is deflected by the deflector 137.1, the primary air flow V2 escapes the deflector 137.1 but is deflected by the deflector 137.2, and the duct air V3 escapes the deflectors 137.1 and 137.2.
• these primary air flows P1 and P3 are, as indicated above, respectively associated with portions 114.1 to 114.3 of grid 114 and, thereby, respectively associated with corresponding zones Z1 to Z3 of the bed formed by solid fuels C on grid 114.
• the zone Z1 of the bed of solid fuels in the combustion installation 101 corresponds to a drying zone for the solid fuels C
• the zone Z2 corresponds to a gasification zone for the volatile part of the solid fuels and of combustion for the solid fuels.
• non-volatile part of these solid fuels and zone Z3 corresponds to a cooling and combustion finishing zone for the non-volatile part of solid fuels.
• an advantageous optional arrangement consists in providing that the subdivisions 132.1 to 132.3 of the air inlet 132 do not have the same cross section, but have cross sections whose respective sizes are different from the from each other : in the example illustrated in figure 1, the subdivision 132.2 is provided with a larger size, of the order of double, than that of the section of each of the subdivisions
• each of the flow rate regulators 134.1 to 134.3 is designed to be controlled by a control unit 140 of the combustion plant 101.
• the control unit 140 comprises electronic and / or electromechanical components, able to generate control signals, which are transmitted to the flow rate regulating members 134.1 to 134.3 in order to actuate the latter individually to control the respective flow rates of the primary air flow P1 to P3.
• the combustion plant 101 further includes optical pyrometers, three of them being visible in Figure 1. All the pyrometers are arranged laterally to the combustion chamber 110, each being provided on at least one of the rear wall 111, of the front wall 112 and of the side walls 113. The pyrometers make it possible to carry out measurements of temperature from the wall of the combustion chamber 110, on which they are provided. In the exemplary embodiment considered in the figures, all these pyrometers are integrated into the side walls 113: more precisely, the side wall 113, visible in Figure 1, thus integrates three pyrometers 150.1 to 150.3. These pyrometers 150.1 to 150.3 are respectively associated with zones Z1 to Z3 of the bed of solid fuels C and, therefore, to regions 114.1 to 114.3 of the grid 114, so that the pyrometer
• the pyrometer 150.1 measures a temperature of the primary combustion of solid fuels C in zone Z1
• the pyrometer 150.2 measures a temperature of the primary combustion of solid fuels in zone Z2
• the pyrometer 150.3 measures a temperature of the primary combustion of solid fuels in zone Z3.
• the temperature measurements are carried out by pyrometers 150.1 to 150.3 as close as possible to the bed of solid fuels C, in particular by pointing the gases G respectively coming from zones Z1 to Z3 of the bed and thus measuring the radiation of the gaseous compounds and of the solid particles present in these G.
• the precise arrangement of the pyrometers 150.1 to 150.3 on the side wall 113 is not restrictive of the invention.
• each pyrometer 150.1 to 150.5 is parallel or substantially parallel, that is to say parallel to within a few degrees, to the plane of the grid 114.
• the pyrometers 150.1 to 150.3 are distributed on the side wall 113 according to the direction of advance Z, while being respectively located vertically plumb with zones Z1 to Z3 of the bed of solid fuels C, as shown schematically in FIG. 1.
• each of the pyrometers 150.1 to 150.3 which are necessarily above the grid 114, is preferably located at a vertical distance from the latter, which is between half and two-thirds of the grid. distance between the grid 114 and the secondary air intake S: in this way, the pyrometers 150.1 to 150.3 are located in the upper half of the vertical gap between the grid 114 and the secondary air intake S, to prevent the flames generated by the primary combustion from disturbing the radiation measurements made by the pyrometers, without being in the upper third of this gap, to prevent the "cold" introduced into the combustion chamber 110 through the secondary air S does not interfere with the measurements made by the pyrometers.
• the type of optical pyrometers 150.1 to 150.3 is not limiting on the invention, since these pyrometers provide temperature measurements based on the intensity of the wavelengths emitted by a radiating body.
• the pyrometers 150.1 to 150.3 are bichromatic laser pyrometers, that is to say that, for the purposes of measuring the temperature of the primary combustion, each pyrometer emits, in the combustion chamber 110, at least one beam laser with two different wavelengths: pyrometers are therefore less sensitive to dust emissions.
• the spectral response of these pyrometers is of the order of 1 ⁇ m.
• the pyrometer 150.1 is designed, for the purpose of measuring the temperature of the primary combustion, to emit two laser beams in the combustion chamber 110, via an opening 113.1 of the side wall 113.
• Each of these two laser beams can be bichromatic, as mentioned above. In all cases, these two laser beams intersect substantially in the plane of the side wall 113. This economical arrangement makes it possible to limit the diameter of the opening 113.1, while keeping a large divergent field of view for the pyrometer.
• the measurements from the pyrometers 150.1 to 150.3 are transmitted, by all appropriate forms of connection, to the control unit 140 in order to be processed automatically by the latter, in particular by a computer or a similar component of the latter.
• the control unit 140 is designed to control the flow rate regulators 134.1 to 134.3, as described above, from the temperature measurements respectively provided by the pyrometers 150.1 to 150.3.
• the combustion installation 101 is in normal operation, that is to say that its combustion chamber 110 is supplied under normal conditions, at the same time, with the solid fuels C, the primary air P and secondary air S, and that the primary and secondary combustions take place there, as explained above.
• the primary air Apart from the aspects relating to the regulation of the primary air which will be presented in detail below, the other aspects of the operation of the combustion plant 101 are well known in the art and will therefore not be presented here further. .
• the pyrometers 150.1 to 150.3 continuously measure the temperature of the primary combustion of the solid fuels in, respectively, zones Z1 to Z3 of the bed.
• the temperature measurements taken by the pyrometers 150.1 to 150.3 are sent continuously to the control unit 140 in order to be automatically processed in real time by the latter.
• the latter compares in real time the temperature measurements provided by each of the pyrometers 150.1 to 150.3 with a temperature setpoint which is specific to the pyrometer in question, in other words which is specific to the zone associated with this pyrometer among the zones Z1 to Z3 of the bed of solid fuels.
• the control unit 140 transmits in real time to the adjustment member corresponding flow rate, that is to say to that of the flow regulating members 134.1 to 134.3 which is associated with the zone concerned, an actuation command so that the flow regulating member acts on the flow rate of the primary air stream, among the primary air streams V1 to V3, which forms, at the outlet of the box 131, the primary air flow P1, P2 or P3 corresponding to the zone associated with the pyrometer concerned.
• control unit 40 activates the flow rate regulator 34.2 to increase the flow rate of the primary air flow P2 by 10%.
• the temperature set points respectively specific to zones Z1 to Z3 are previously supplied to the control unit 140. These temperature set points can be pre-set for the combustion installation 101 or, preferably, are determined, in particular by calculation. , from a reference temperature to which a correction is applied which is linked to the zone concerned among the zones Z1 to Z3 and which, where appropriate, is also linked to the characteristics of the solid fuels S, possibly continuously measured , such as their calorific value, humidity, etc.
• the aforementioned reference temperature is, for its part, either pre-fixed or determined, if necessary continuously, from the oxygen content in the flue gases F, this content being typically measured at the outlet of the boiler, as mentioned in the introductory part of this document.
• control unit 140 can implement other treatments than that which has just been described, in particular as long as these other treatments compare the measurements of the pyrometers 150.1 to 150.3 with temperature setpoints. respective, which are specific to zones Z1 to Z3, in order to individually control the flow rate of the primary air flows P1 to P3.
• control unit 140 and the flow rate regulating members 134.1 to 134.3 jointly form regulation means which make it possible, from the measurements of the pyrometers 150.1 to 150.3, to regulate the respective flow rates of the flows.
• the reaction time for these regulation means is very low, even almost instantaneous.
• the actuation of the flow rate regulators 134.1 to 134.3, controlled by the control unit 140 can be expected within a substantial but limited range of variation.
• the limits of this range of variation are predetermined by experience and / or by other parameters. operations of the combustion installation 101, such as the tonnage of solid fuels C introduced into the combustion chamber 110, the pressure of the primary air P in the supply line 135, the vapor flow rate produced by the boiler exchangers, etc.
• the reference temperature can be compared to the instantaneous average of the temperature measurements provided by the pyrometers 150.1 to 150.3, weighted by the size of the zones Z1 to Z3 respectively associated with these pyrometers.
• a pair of pyrometers can thus be associated with at least one of zones Z1 to Z3, or even with each of zones Z1 to Z3, the two pyrometers of each pair being provided on respectively one and the other of the two side walls 113, typically facing each other horizontally, which makes it possible to measure the temperature of the primary combustion in the zone concerned from each lateral side of the grate 114.
• the measurements respectively coming from the different pyrometers for a given bed area are then averaged for processing purposes by control unit 140.
• the number, according to which the bed of solid fuels C is distributed into zones and therefore according to which the grid 114 is distributed into regions, may differ from that envisaged for the combustion installation 101.
• this number is preferably of at least three in order to include the three main zones corresponding to the successive physico-chemical effects of primary combustion, namely a drying zone for solid fuels, a gasification zone for a volatile part of the solid fuels and combustion for a non-volatile part of solid fuels, and a cooling and combustion finishing zone for the non-volatile part of solid fuels.
• each of the pyrometers 150.1 to 150.3 is preferably located, above the grid 114, at a vertical distance. between 1.5 m and 5 m opposite this grid.
• the advantages associated with pyrometers 150.1 to 150.3 and the automatic processing of their measurement by the control unit 140 are numerous. Indeed, as the temperature measurements made by the pyrometers are instantaneous and as close as possible to the primary combustion, the regulation of the combustion installation 101 can be carried out in real time, or in any case with very short reaction times, which are adapted to the speeds observed for the complex phenomena linked to primary combustion.
• the response time and the representativeness of the temperature measurements by the pyrometers allow a high precision of the primary air dosage and a good control of the ratio between the quantity of air consumed by the primary combustion and the quantity of solid fuels burned by primary combustion, in different zones of the bed formed by solid fuels, in particular the three main zones mentioned above.
• the radiative temperature measured by pyrometers, is an indicator close to the adiabatic temperature of the primary combustion, that is to say of the theoretical temperature so that the combustion primary is complete, in the sense that, like the adiabatic temperature, the radiative temperature of the primary combustion is very sensitive to both the quantity of air consumed by the primary combustion and the quantity of fuels burnt during combustion primary.
• This adjustment "as closely as possible" to the quantity of primary air induces a reduction in the overall flow of primary air, which is favorable to a reduction in the size of the combustion installation, to its energy efficiency and to a reduction. pollutant emissions.
• Adjusting the quantity of primary air “as closely as possible” also makes it possible to control the temperatures throughout the lower part of the combustion chamber. This makes it possible to improve the performance of the equipment downstream of the combustion chamber, in particular the production of steam by the exchangers of the boiler. This also makes it possible to limit the formation, by melting, of oxides at high temperature, sources of deposits which affect the thermal efficiency and which are difficult to remove by the usual cleaning techniques. This also makes it possible to considerably reduce, or even eliminate, the need for secondary air and / or to reduce the number of vertical secondary air injection levels. The combustion installation is thereby simplified, at least by reducing the volume between the grille and the secondary air intake, which is a source of significant savings.
• Controlling the temperatures in the lower part of the combustion chamber also avoids excessive local temperature peaks and makes it possible to use, for solid fuels with high calorific value, traditional systems generally limited to solid fuels with lower power.
• calorific such as uncooled water grids or standard refractory linings, especially non-nitrided.
• the combustion installation 101 is devoid of the pyrometers 150.1 to 150.3, so that the regulation of the flow rate regulating members 134.1 to 134.3 is modified accordingly, as explained below.
• each flow adjustment member 134.1 to 134.3 is designed to be actuated manually.
• a control unit similar to the control unit 40 is unnecessary.
• the actuation of each of the flow rate regulating members 134.1 to 134.3 is then carried out only occasionally by an operator, for example as a function of the average calorific value of the solid fuels C, determined over a long period of time, or depending on a known variation in the composition of solid fuels.
• the combustion plant 101 comprises a control unit similar to the control unit 140, being able to actuate individually the flow rate regulators 134.1 to 134.3.
• 134.1 to 134.3 can either result directly from dedicated instructions from an operator acting on an interface of the control unit, or be deduced from an automatic processing which is carried out by the control unit from data provided to it.
• the data may relate to solid fuels C, for example relating to their calorific value, type, composition, etc.
• the data supplied to the control unit can also be measurements relating to operating conditions of the combustion chamber 110, for example images provided by an infrared camera observing the interior of the combustion chamber.
• the combustion installation 101 provides, in particular compared to existing combustion plants, economic and compact advantages. Indeed, instead of using a group of several separate boxes, the combustion installation 101 provides only the single box 131 to admit the primary air P under the grid 114, by subdividing its air inlet 132 and the presence of internal aeraulic arrangements of its casing 133, such as the deflectors

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• 2019
  • 2019-11-08 FR FR1912553A patent/FR3103026B1/fr active Active
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