FR3103027A1 - Method of regulating a combustion installation, as well as the corresponding combustion installation - Google Patents

Abstract

Method of regulating a combustion plant, as well as corresponding combustion plant In this method of regulating a combustion plant (1), solid fuels (C) are introduced into a combustion chamber (10) and therein burn according to primary combustion in the presence of primary air (P) which is introduced into the combustion chamber with a flow of primary air. To control the primary combustion carried out in this installation, provision is made for the primary combustion of solid fuels to have a temperature which is measured in the combustion chamber by one or more optical pyrometers (50.1 to 50.5) which are arranged laterally to the combustion chamber. combustion, and that the primary air flow is controlled according to the measurements of the pyrometer (s). Figure for abstract: Figure 1

Description

Method for controlling a combustion plant, as well as corresponding combustion plant

The present invention relates to a method for regulating a combustion installation. It also relates to a combustion installation.

The invention relates in particular to combustion installations integrated into a boiler which transfers the heat given off by combustion to a heat transfer fluid, generally water.

Whatever the field of application of the invention, the combustion plants concerned use, as fuel, 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. Thus, the solid fuels considered here typically form a flow of matter, the exact composition of which is both inhomogeneous at a given instant and liable to vary over time.

In such combustion installations, the solid fuels are introduced into a combustion chamber in order to undergo therein a combustion, called primary combustion, in the presence of air called primary air, this primary combustion leading to the fact that, on the one hand, the non-volatile part of the solid fuels is completely burned, except for particulate unburnt matter, 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, is partially burned. This primary combustion can in particular be carried out on a grate, which delimits the combustion chamber downwards and onto which the solid fuels are loaded to undergo the primary combustion there, 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. In order for the volatile part of the solid fuels to be completely burned and thus to operate a so-called secondary combustion, it is often provided that air called secondary air, consisting of air and/or recirculated fumes, is admitted into the combustion chamber. , being injected above the grid in one or more levels.

In all cases, all the chemical and physical reactions, which will condition the composition of the combustion gases and the particles fluidized by these gases in the combustion chamber and then downstream of it, in particular in the heat exchangers of the boiler, are initiated by primary combustion. It is therefore desirable to control as much as possible the conditions under which the primary combustion is carried out. In particular, the primary air intake conditions are critical, in the sense that they influence in particular the primary combustion temperature and the partial pressures of the volatile compounds in the combustion gases, which affects the reactions. physical and chemical factors of primary combustion, as well as the entrainment of particles in the combustion gases.

Solid fuels of the waste or biomass type are characterized by high heterogeneity both in size of the solid fragments composing them, and in composition and humidity. This strong heterogeneity leads, at the same time, to a strong disparity, in time and in space, for the physico-chemical properties of combustion relating to these solid fuels, such as their calorific value, their stoichiometric air requirement, their kinetics combustion, etc., and poor physical distribution of these solid fuels in the combustion chamber, in particular on the grate of the latter. This heterogeneity often leads to combustion being voluntarily carried out with a large excess of air compared to the stoichiometric requirement, in order to limit unburnt matter. This excess air is often all the greater as the heterogeneity of the solid fuels is important, in order to ensure that the primary combustion is as complete as possible. The heterogeneity of solid fuels also frequently leads to the admission of primary air into the combustion chamber, typically through the grid of the latter, being poorly distributed in space, due to the inhomogeneity the pressure drop generated by the layer formed by the solid fuels on the grate. The inhomogeneity relating to this layer results in particular from the variability in the size and density of the solid fragments present in the fuels, from the system for depositing solid fuels on the grate, and from the disparity for the combustion kinetics relating to these solid fuels.

In practice, excess and/or poorly distributed primary air intake leads to many disadvantages:

- The formation of nitrogen oxides, by oxidation of the nitrogen contained in the primary air, is favored by poor control of the admission of primary air into solid fuels, either due to an excess too much air overall, or by a local lack of primary air leading to a local temperature that is too high and thus promoting the oxidation of nitrogen in the air.

- If the formation of molten salts is unavoidable, taking into account the temperature of the primary combustion, the oxides whose melting temperature is between 1100 and 1400°C are partly molten and partly solid. The distribution between solid matter and molten matter depends of course on the composition of the solid fuels but also, for a given composition, on the temperature of the primary combustion and therefore on the conditions of the primary air intake.

- The greater the excess primary air, the greater the speed of the gases generated by the primary combustion, thus promoting the entrainment of solid particles and liquid droplets, which will participate in fouling, corrosion and erosion of equipment downstream of the combustion chamber, in particular the heat exchangers of the boiler.

- The poor distribution of the primary air under the grate of the combustion chamber affects the homogeneity of the thickness of the layer of ash present on the grate, while this layer of ash provides effective protection against direct radiation from primary combustion, which can generate undesirable heating and, therefore, the destruction of the components of the grate. Indeed, the protective layer of ash, especially when the solid fuels are biomass which usually generates less ash than household waste or coal, can quickly disappear from a significant portion of the grate, due to 'too rapid combustion and/or flights of ash under the effect of too high speeds for the primary air at this portion of the grate. This last phenomenon of flights is moreover accentuated by the fact that if the layer of ash disappears or decreases locally, the corresponding portion of the grid sees its loss of load decrease, generating at the level of this portion a flow of larger and faster primary air.

- the insufficient control of the primary combustion forces the addition of a significant quantity of secondary air to operate the secondary combustion mentioned above. This secondary air is stirred with the gases resulting from the primary combustion in order to complete the combustion reactions and thus oxidize the partially oxidized compounds, such as carbon monoxide, pyrolysis gases and, more generally, the compounds unburned organic matter, whether gaseous or particulate. Admission of secondary air increases the flow of fumes leaving the combustion plant, which requires sizing the combustion plant and, where applicable, the entire boiler, as well as the treatment of the fumes in downstream of the boiler. In particular, the air present in the secondary air in excess beyond the stoichiometric quantity necessary for secondary combustion generates a higher volume of fumes and therefore a larger size for the combustion chamber in order to maintain the times of combustion. stay necessary for secondary combustion. Similarly, the recirculated fumes, present in the secondary air, increase the volume of fumes, without supplying oxygen for the secondary combustion, and therefore increase the size of the combustion chamber. In any case, the secondary air intake leads to an increase in electrical consumption for the secondary air supply fans and the draft fans. In addition, the admission of secondary air tends to reduce the residence time in the combustion chamber, which, on the one hand, is unfavorable to the reduction of nitrogen oxides by compounds, such as ammonia or urea, injected into the combustion chamber and, on the other hand, delays the vitrification of molten oxides, leading to fouling downstream of the combustion chamber, in particular in the boiler exchangers.

Faced with these difficulties, several techniques have been developed so far.

One of these techniques consists in regulating the total flow of the primary air according to the oxygen content in the fumes from the combustion installation. In practice, the measurement of this oxygen content is carried out in the "cold" flue gases, typically at the boiler outlet, to ensure the resistance of the measurement sensor over time. Taking into account, on the one hand, the distance between the combustion chamber and the "cold" zone where the measurement sensor is located and, on the other hand, the response time of this measurement sensor being at least five seconds, the measurement of the oxygen content has a reaction time of more than half a minute, which significantly limits the regulation performance for the admission of the primary air. Moreover, this measurement of the oxygen content does not accurately reflect the heterogeneity of solid fuels. In addition, the measurement of the oxygen content in wet flue gases is affected by the dilution induced by the water vapor present in the flue gases, which depends on the humidity and the hydrogen content of the solid fuels. To circumvent this difficulty, the oxygen content can be measured on "dry" flue gases, which requires taking and drying samples of flue gases before measuring the oxygen content. But the reaction time is then lengthened to allow the implementation of this sampling and this drying, typically of the order of twenty to forty additional seconds.

Another technique, which can be combined with the previous one, consists in distributing the primary air by means of several boxes, which are arranged under the grille and which are each equipped, on their air inlet, with a flow adjustment device to control the primary air flow through the box. The adjustment devices thus make it possible to distribute the total flow of primary air between the respective outlets of the boxes. In practice, the adjustment of the adjusting members is often carried out only occasionally by an operator, for example according to the average calorific value of solid fuels, determined over a long period of time, or according to a known variation the composition of solid fuels. In more sophisticated installations, 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. However, apart from the expensive nature of such an infrared camera and the associated image processing, this infrared camera does not provide information on the actual temperature of the primary combustion of solid fuels, but only delivers a partial indication of the surface temperature of the the whole of the layer of solid fuels, this partial indication being moreover disturbed by the particles and the dust, present vertically between the layer of solid fuels and the infrared camera. As a result, the total primary air flow is often intentionally increased to prevent primary combustion from being incomplete.

Thus, the performance of the various existing techniques is limited.

The object of the present invention is to propose an improved regulation of a solid fuel combustion installation, in order to control the primary combustion carried out in this installation.

To this end, the subject of the invention is a process for regulating a combustion installation, in which solid fuels are introduced into a combustion chamber and burn there according to a primary combustion in the presence of primary air which is introduced into the combustion chamber with a flow of primary air. According to the invention, the primary combustion of solid fuels has a temperature which is measured in the combustion chamber by one or more optical pyrometers which are arranged laterally to the combustion chamber, the primary air flow being controlled as a function of the measurements of the pyrometer(s).

The invention also relates to a combustion installation, comprising a combustion chamber, adapted so that solid fuels are introduced therein and burn therein according to a primary combustion in the presence of primary air, and an intake device, adapted to supplying the combustion chamber with the primary air according to a primary air flow. According to the invention, the combustion installation further comprises one or more optical pyrometers, which are arranged laterally to the combustion chamber and which are suitable for measuring a temperature of the primary combustion in the combustion chamber, and means of regulation adapted to, from the measurements of the pyrometer or pyrometers, control the primary air flow of the intake device.

One of the ideas underlying the invention is to use one or more optical pyrometers, which, by definition, provide temperature measurements based on the intensity of the wavelengths emitted by a radiating body. These pyrometers are arranged laterally to the combustion chamber so as to measure a temperature of the primary combustion, by carrying out their measurement as close as possible to the solid fuels being burned in order to know the intensity of the radiation of the primary combustion, in in particular the radiation of the combustion gases at the time of their generation by the primary combustion and the radiation of the particles which these combustion gases contain. The measurements provided by the or each pyrometer are representative, in real time, of the temperature of the primary combustion, in the sense that these measurements are instantaneous and integrate the thermal conditions on the optical path between the pyrometer and the solid fuels, in particular without be affected by fouling or wall effects. The temperature thus measured by this or these pyrometers can be qualified as the radiative temperature of the primary combustion.

The invention also provides for using this radiative temperature to control the flow of primary air and, advantageously, the distribution of this flow of primary air in the combustion chamber. Indeed, without wishing to be bound by a theory, the inventors have established that this radiative temperature is an indicator close to the adiabatic temperature of the primary combustion, that is to say the theoretical temperature for the primary combustion to be complete. , in the sense that, like the adiabatic temperature, the radiative temperature of the primary combustion is very sensitive to both the amount of air consumed by the primary combustion and the amount of fuels burned in the primary combustion. Thus, for a given zone of solid fuels, pointed by the or one of the pyrometers, the temperature measured by this pyrometer is an excellent indicator of the ratio between the quantity of solid fuels actually burned and the flow of air actually consumed in the zone of combustion. Thanks to the invention, the flow of primary air admitted into the combustion chamber is regulated according to the temperature measurements provided by the pyrometer(s), in particular by comparison with a temperature setpoint, as explained in more detail below. . Advantageously, the invention provides for measuring the temperature of the primary combustion in several zones of the solid fuels, by respective pyrometers, and for adjusting the primary air flow zone by zone. In all cases, the invention makes it possible to control in real time the admission of primary air into the combustion chamber so as to provide, advantageously zone by zone, the quantity of primary air necessary and sufficient for combustion primary is complete, in other words so as to optimize, advantageously zone by zone, the ratio between the primary air admitted and the quantity of fuel burned. This mastery of primary combustion, made possible by the invention, has many advantages, as detailed below.

The invention is applicable to combustion installations in the combustion chamber of which the solid fuels form either a fluidized bed or a moving bed on a grate. In the second case, the invention is of remarkable interest, in connection with the possibility of dividing the bed of solid fuels into several successive zones in the direction of advance of the bed, as explained in more detail below.

According to additional advantageous characteristics of the control method and of the combustion installation in accordance with the invention, taken in isolation or in all technically possible combinations:

- The combustion chamber is delimited downwards by a grate on which the solid fuels form a bed which is movable in a direction of advance in the combustion chamber, and the primary air is admitted under the grate, with a flow rate of primary air, before passing through the grate to enter the combustion chamber and reach the bed of solid fuels.

- The bed of solid fuels is divided into several zones which follow one another according to the direction of advancement, each of the zones is associated with at least one of the pyrometers so that, for each zone, the pyrometer(s) associated with the zone measure the temperature of the primary combustion of solid fuels in this zone, and the primary air is admitted under the grate being divided into primary air flows which are respectively associated with the zones in such a way that, for each zone, the flow of primary air associated with the zone is sent to this zone with a flow rate which is controlled according to the measurements of the pyrometer(s) associated with this zone.

- The zones are at least three in number and include: - a drying zone for solid fuels,
- a gasification zone for a volatile part of the solid fuels and a combustion zone for a non-volatile part of the solid fuels, and
- a cooling and combustion finishing zone for the non-volatile part of the solid fuels.

- The primary air is admitted under the grille by being distributed by separate boxes which are respectively associated with the zones so that, for each zone, the primary air flow associated with the zone is formed at an air outlet of the box associated with this zone while an air inlet of the box associated with the zone is provided with a flow control member controlled according to the measurements of the pyrometer(s) associated with this zone.

- The primary air is admitted under the grid by a single box which:
- has an air inlet divided into several subdivisions, which are respectively associated with the zones and in which separate respective primary air streams flow, each subdivision being provided with a flow adjustment member, controlled according to the measurements of the pyrometer(s) associated with the corresponding zone, and

- is provided with internal fittings which direct the air streams leaving the air inlet, towards the grille to form the primary air flows respectively.

- Secondary air is admitted into the combustion chamber above the grate to effect secondary combustion of gases generated by the primary combustion of solid fuels, and the pyrometer(s) are located at a vertical distance from the grate, which is between half and two thirds of the gap between the grille and the secondary air intake.

- To measure the temperature of the primary combustion of solid fuels, the or each pyrometer emits at least one bichromatic laser beam into the combustion chamber.

- To measure the temperature of the primary combustion of solid fuels, the or each pyrometer emits two laser beams into the combustion chamber which intersect substantially in the plane of a wall of the combustion chamber, on which the pyrometer is provided.

- The combustion installation further comprises a grate which delimits the combustion chamber downwards, which is adapted to support a bed which is formed by the solid fuels and which is movable in a forward direction in the combustion chamber , and under which the intake device opens so that the primary air supplied by the intake device according to the primary air flow enters the combustion chamber through the grille; the intake device is suitable both for distributing the primary air into primary air flows, and for sending these primary air flows respectively to associated regions of the grid, which follow one another in the direction advancement; and the regulating means are adapted to control the flow rate of each of the primary air flows from the measurements of the pyrometer(s) measuring the primary combustion temperature of a zone of the bed, which is supported by the region of the grid, to which the intake device sends the primary airflow.

The invention will be better understood on reading the following description, given solely by way of example and made with reference to the drawings in which:

FIG. 1 is a diagram of a combustion installation according to the invention;

Figure 2 is a partial schematic section along line II-II of Figure 1;

FIG. 3 is a view similar to FIG. 1, illustrating another embodiment of a combustion installation according to the invention; And

Figure 4 is a view on a larger scale of a box IV of Figure 3, illustrating a variant of the corresponding part of the combustion installation.

In Figure 1 is shown a combustion plant 1 suitable for burning solid fuels C.

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.

Combustion installation 1 typically belongs to a boiler which makes it possible to produce steam by using the heat of the fumes from the combustion installation.

The combustion installation 1 comprises a combustion chamber 10 adapted so that the solid fuels C are introduced therein and burn there according to a primary combustion in the presence of air, called primary air P. The combustion chamber 10 is delimited laterally by:

- a rear wall 11, through which the solid fuels C are loaded inside the combustion chamber by, for example, an external chute 20,

- by a front wall 12, through which the solid fuels C, once burned, leave the combustion chamber via an outlet 21, and

- by two side walls 13, which are horizontally distant from each other and which each connect the rear 11 and front 12 walls, only one of these two side walls 13 being visible in figure 1.

The combustion chamber 10 is designed so that, once the solid fuels C are loaded therein, these solid fuels C 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 10 is designed to channel these gases, until they exit from the combustion chamber 10 from which escape fumes F circulating in equipment of the boiler, such as heat exchangers.

In the embodiment considered in Figure 1, the combustion chamber 10 is provided to admit secondary air S, consisting of recirculated air and/or fumes. As shown in Figure 1, the secondary air intake S in the combustion chamber 10 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 primary combustion of solid fuels C, without including secondary air S, while the mixture between these gases G and the secondary air S is referenced GS in FIG. 1 and forms the fumes F at the outlet of the combustion chamber 10 In practice, the secondary air can thus be introduced in several vertical levels, as shown 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 entirely burned, except for the particulate unburnt 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, or partially burned, forming the gases G. The secondary air S supplies secondary combustion, namely the combustion of the gases G to form the gases GS, thus completely burning the volatile part of the solid fuels C.

In the embodiment considered here, the combustion chamber 10 comprises a grid 14 which delimits the bottom of the combustion chamber. This grate 14 is designed to support the solid fuels C inside the combustion chamber 10 in such a way that, as illustrated in FIG. 1, these solid fuels form a bed which rests on the grate 14, extending from the rear wall 11 to the front wall 12. At the level of the rear wall 11, the bed is supplied with solid fuels to be burned, for example by the outer chute 20, while, at the level of the front wall 12, the bed is evacuated, in particular by falling into the evacuation 21. Between the rear 11 and front 12 walls, the bed of solid fuels C is movable in a direction of advancement Z in the combustion chamber 10. Thus, the direction of advancement Z extends from the rear wall 11 to the front wall 12, while being parallel to the grid 14. In practice, the grid 14 may as well be inclined with respect to a horizontal plane, as in FIG. extend in a horizontal plane. In all cases, the grid 14 has two side edges, which are opposite each other in a horizontal direction perpendicular to the direction of advancement Z and which extend respectively along the two side walls 13 of the combustion chamber 10. The arrangements of the combustion chamber 10, which drive the bed of solid fuels C along the direction of advancement Z, are not limiting of the invention: in a manner known per se, the grate 14 can be provided inclined to allow the gravity drive of the bed and/or be provided mobile to act on the drive of the bed, while being then animated by a movement allowing a slow movement of the solid fuels from their point of arrival on the grate, where they are not yet burnt, to their point of exit from the grate, where they are completely burnt. In the case where the grid is mobile, various drive systems are known, so that, for example, the grid rotates like a conveyor belt, or the bars of the grid move alternately, etc.

In practice, the embodiment of the grid 14 can also be linked to the device for introducing solid fuels C into the combustion chamber. Indeed, rather than supplying the combustion chamber 10 with solid fuels through the rear wall 11 by means of the external chute 20 as in FIG. 1, the solid fuels C can be introduced through another wall of the combustion chamber, in particular through the front wall 12, the introduction device then being an external injector, mechanical and/or pneumatic, which is able to project the solid fuels into the combustion chamber, from the wall front to the region of the grid 14, adjoining the rear wall 11.

Whatever the embodiment of the grid 14, the primary air P is admitted under the grid and this grid 14 is designed to let the primary air P cross from bottom to top to allow the latter to enter in the combustion chamber 10 and thus reach the bed of solid fuels C.

The combustion installation 1 also comprises an intake device 30 making it possible to supply the combustion chamber 10 with the primary air P. In the example embodiment considered here, the intake device 30 is, at least for its downstream outlet, arranged below gate 14.

As seen in Figure 1, the intake device 30 comprises several separate boxes, which are here five in number, being respectively referenced 31.1, 31.2, 31.3, 31.4 and 31.5, and which are arranged under the grid 14, in succeeding each other in the direction of advance Z. Each of the boxes 31.1 to 31.5 is designed to form, from the primary air P, a flow of primary air P1 to P5. To this end, each box 31.1 to 31.5 is designed to receive primary air P via an air inlet 32.1 to 32.5 of the box and to channel the air passing through it to an air outlet 33.1 to 33.5 d where emerges the corresponding primary air flow P1 to P5. The flow rate of primary air P admitted into the combustion chamber 10 by the intake device 30, in other words the total flow rate of the primary air P passing through the intake device 30, corresponds to the sum of the respective flow rates of the primary air flow P1 to P5.

The air inlets 32.1 to 32.5 are provided to be supplied with the primary air P, being connected, upstream of the boxes 31.1 to 31.5, to a common supply line 35, carrying the primary air P.

The air outlets 33.1 to 33.5 are arranged under the grid 14, being respectively located vertically plumb with corresponding regions 14.1 to 14.5 of the grid, which follow one another in the direction of advancement Z. Thus , each of the boxes 31.1 to 31.5 opens upwards, via its air outlet 33.1 to 33.5, on the underside of the corresponding region 14.1 to 14.5 of the grid 14 and sends its primary air flow P1 to P5 respectively towards the regions 14.1 to 14.5 of the grid, as illustrated in FIG. 1. It will be understood that the regions 14.1 to 14.5 of the grid 14 are fixed in the combustion chamber 10, and this regardless of the embodiment of the grid 14: thus, when the grid 14 is fixed in the combustion chamber 10, each of the regions 14.1 to 14.5 corresponds to a part of this grid, which is unchanged during the operation of the combustion installation 1; when the grate 14 is mobile, each of the regions 14.1 to 14.5 is, at each moment of the operation of the combustion installation 1, occupied by a part of the grate 14, this part being able to change region during the movement of the grate 14 In FIG. 1, region 14.1 is, among regions 14.1 to 14.5, closest to rear wall 11 while region 14.5 is closest to front wall 12, this region 14.5 succeeding region 14.4 which itself succeeds region 14.3 which itself succeeds region 14.2 which itself succeeds region 14.1 in the direction of advance Z.

Zones of the bed of solid fuels C are denoted Z1 to Z5, which follow one another in the direction of advancement Z and which are respectively located vertically plumb with the regions 14.1 to 14.5 of the grid 14. In other words, the zone Z1 of the bed of solid fuels C rests on region 14.1 of grid 14, zone Z2 rests on region 14.2, and so on, up to zone Z5 of the bed, which rests on region 14.5 of grid 14. Similarly to regions 14.1 to 14.5 of grid 14, zones Z1 to Z5 of the bed of solid fuels C are fixed in combustion chamber 10. It is therefore understood that, at a given moment of operation of the combustion installation 1, each of the zones Z1 to Z5 of the bed consists of a part of the solid fuels C and that, at a later moment of the operation of the combustion installation, each of the zones Z1 to Z5 of the bed is occupied by another part solid fuels C, at least partially different from the aforementioned part of these solid fuels C, due to the displacement of the bed in the direction of advancement Z. Thus, during their primary combustion, the solid fuels C pass progressively, in the combustion chamber 10, through zone Z1 of the bed formed by these fuels C on grid 14, then through zone Z2, then through zone Z3, then through zone Z4, and finally through zone Z5 of the bed. Progressing in this way through zones Z1 to Z5, the solid fuels C undergo the progressive effects of primary combustion, namely first their drying, then a gasification for their volatile part and a combustion for their non-volatile part, and finally a cooling and a combustion finish for their non-volatile part. By way of example, zone Z1 is provided to correspond to a drying zone for the solid fuels C, zones Z2 and Z3 are provided to correspond to a gasification zone for the volatile part of the solid fuels and combustion for the non-volatile part of the solid fuels, and zones Z4 and Z5 are provided to correspond to a combustion finish zone for the non-volatile part of the solid fuels and cooling.

As shown schematically in Figure 1, each of the air inlets 32.1 to 32.5 of the boxes 31.1 to 31.5 is provided with a flow control member 34.1 to 34.5. The embodiment of these flow adjustment members 34.1 to 34.5 does not limit the invention, as long as each of these flow adjustment members 34.1 to 34.5 makes it possible to control the flow rate of the primary air flow P1 to P5 associated with the corresponding subwoofer. The flow control members are for example valves, dampers, etc.

In all cases, each of the flow adjustment members 34.1 to 34.5 is designed to be controlled by a control unit 40 of the combustion installation 1. The control unit 40 comprises electronic and/or electromechanical components, to even to generate control signals, which are transmitted to the flow adjustment members 34.1 to 34.5 in order to individually actuate the latter to control the respective flow rates of the primary air flows P1 to P5. Here again, the material specificities of the control unit 40, as well as those of the connection between the latter and the flow adjustment members 34.1 to 34.5 are not limiting of the invention.

As shown in Figure 1, the combustion installation 1 further comprises optical pyrometers, five of them being visible in Figure 1. All the pyrometers are arranged laterally to the combustion chamber 10, each being provided on at least one of the rear wall 11, the front wall 12 and the side walls 13. The pyrometers make it possible to take temperature measurements from the wall of the combustion chamber 10, on which they are provided. In the embodiment considered in the figures, all these pyrometers are integrated into the side walls 13: more precisely, the side wall 13, visible in FIG. 1, thus integrates five pyrometers 50.1 to 50.5. These pyrometers 50.1 to 50.5 are respectively associated with the zones Z1 to Z5 of the solid fuel bed C and, thereby, with the regions 14.1 to 14.5 of the grid 14, so that the pyrometer 50.1 measures a temperature of the primary combustion of the fuels solids C in the zone Z1, the pyrometer 50.2 measures a temperature of the primary combustion of the solid fuels in the zone Z2, and so on, up to the pyrometer 50.5 which measures a temperature of the primary combustion of the solid fuels in the zone Z5 . The temperature measurements are carried out by the pyrometers 50.1 to 50.5 closest to the bed of solid fuels C, by pointing in particular to the gases G respectively originating from the zones Z1 to Z5 of the bed and thus measuring the radiation of the gaseous compounds and the solid particles present in these gases G.

In practice, the precise arrangement of the pyrometers 50.1 to 50.5 on the side wall 13 does not limit the invention. This being so, as a preference, in particular to limit the optical path between the pyrometers and the primary combustion, in particular the gases G, and to have maximum integration of the thermal radiation emitted by the primary combustion, the pyrometers 50.1 to 50.5 are distributed over the side wall 13 along the direction of advancement Z, being respectively located vertically plumb with zones Z1 to Z5 of the bed of solid fuels C, as indicated schematically in FIG. 1. Furthermore, along the vertical direction, each of the pyrometers 50.1 to 50.5, which are necessarily above the grid 14, is preferably located at a vertical distance from the latter, which is between half and two thirds of the spacing between the grid 14 and the inlet secondary air S: in this way, the pyrometers 50.1 to 50.5 are located in the upper half of the vertical gap between the grid 14 and the secondary air intake S, to prevent flames generated by the combustion primary do not disturb the radiation measurements carried out by the pyrometers, without however being in the upper third of this spacing, to prevent the "cold" introduced into the combustion chamber 10 by the secondary air S from disturbing the measurements carried out by pyrometers.

Similarly, the type of optical pyrometers 50.1 to 50.5 does not limit the invention, since these pyrometers provide temperature measurements based on the intensity of the wavelengths emitted by a radiating body. Preferably, the pyrometers 50.1 to 50.5 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 10, at least one beam laser with two different wavelengths: pyrometers are less sensitive to dust emissions. For example, the spectral response of these pyrometers is of the order of 1 µm.

Moreover, the specificities relating to the focusing of the pyrometers 50.1 to 50.5 do not limit the invention either. This being so, a preferred embodiment is illustrated in FIG. 2 for the pyrometer 50.1, it being understood that this embodiment is applicable to the other pyrometers 50.2 to 50.5. Thus, as shown in Figure 2, the pyrometer 50.1 is designed, for the purpose of measuring the temperature of the primary combustion, to emit two laser beams into the combustion chamber 10, via an opening 13.1 of the side wall 13. 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 13. This economical arrangement makes it possible to limit the diameter of the opening 13.1, while keeping a large divergent field of view for the pyrometer.

In all cases, the measurements of the pyrometers 50.1 to 50.5 are transmitted, by any appropriate form of link, to the control unit 40 in order to be automatically processed by the latter, in particular by a computer or a similar component of the latter. . Whatever the specifics of the processing which is carried out by the control unit and examples of which will be given later, the control unit 40 is designed to control each of the flow rate adjustment members 34.1 to 34.5, as described above. , from the temperature measurements respectively supplied by the pyrometers 50.1 to 50.5.

Aspects relating to the control of the combustion plant 1 are further described below.

In this context, it is considered that the combustion installation 1 is in normal operation, that is to say that its combustion chamber 10 is fed under normal conditions, both 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. 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 1 are well known in the art and will therefore not be presented here any further. .

While the combustion chamber 10 is operating under normal conditions, the pyrometers 50.1 to 50.5 continuously measure the temperature of the primary combustion of the solid fuels in the zones Z1 to Z5 of the bed, respectively. The temperature measurements taken by the pyrometers 50.1 to 50.5 are sent continuously to the control unit 40 in order to be automatically processed in real time by the latter. According to a preferred embodiment for the processing carried out by the control unit 40, the latter compares in real time the temperature measurements provided by each of the pyrometers 50.1 to 50.5 with a temperature setpoint which is specific to the pyrometer considered, in other words which is specific to the zone associated with this pyrometer among the zones Z1 to Z5 of the bed of solid fuels. According to the result of this comparison specific to each of the zones Z1 to Z5, the control unit 40 transmits in real time to the corresponding flow adjustment member, that is to say to that of the flow adjustment members 34.1 to 34.5 which is associated with the zone concerned, an actuation control so that the flow adjustment member acts on the flow rate of the primary air flow, among the primary air flows P1 to P5, which corresponds to the zone associated with the pyrometer concerned. For example, if, for zone Z2, the temperature measured by pyrometer 50.2 is 5% lower than the temperature setpoint specific to zone Z2 for more than five to ten consecutive seconds, control unit 40 activates the flow rate adjuster 34.2 to increase the flow rate of the primary air flow P2 by 10%.

In practice, the temperature setpoints respectively specific to the zones Z1 to Z5 are provided beforehand to the control unit 40. These temperature setpoints can be prefixed for the combustion installation 1 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 Z5 and which, if necessary, is also linked to the characteristics of the solid fuels S, possibly measured continuously , such as their calorific value, humidity, etc. The aforementioned reference temperature is, for its part, either prefixed, 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.

Of course, other processing than that which has just been described can be implemented by the control unit 40, in particular as long as these other processing compare the measurements of the pyrometers 50.1 to 50.5 with temperature setpoints respective, which are specific to zones Z1 to Z5, in order to individually control the flow rate of the primary air flows P1 to P5. In all cases, it is understood that the control unit 40 and the flow adjustment members 34.1 to 34.5 jointly form regulation means which make it possible, from the measurements of the pyrometers 50.1 to 50.5, to regulate the respective flow rates of the flows of primary air P1 to P5 and, thereby, the total flow of primary air P supplied by the intake device 30 to the combustion chamber 10. The reaction time for these regulation means is very low, almost instantaneous.

As a safety measure, in particular to prevent the flow rate of the primary air flows P1 to P5 from being too low or too high, the actuation of the flow adjustment members 34.1 to 34.5, controlled by the control unit 40, can be expected within a substantial but limited range of variation. The limits of this variation range are predetermined by experience and/or by other operating parameters of the combustion plant 1, such as the tonnage of solid fuels C introduced into the combustion chamber 10, the pressure of the primary air P in the supply pipe 35, the flow rate of steam produced by the exchanger(s) of the boiler, etc. Also by way of control and safety, the reference temperature, mentioned above, can be compared with the instantaneous average of the temperature measurements provided by the pyrometers 50.1 to 50.5, weighted by the size of the zones Z1 to Z5 respectively associated with these pyrometers.

In Figure 3 is shown, as a variant of the combustion plant 1, a combustion plant 101.

Combustion plant 101 is functionally similar to combustion plant 1 and, like the latter, can be integrated into a boiler.

The combustion installation 101 comprises a combustion chamber 110 which is functionally, even structurally similar to the combustion chamber 10 of the combustion installation 1. Thus, the combustion chamber 110 is provided to be fed by solid fuels C , the primary air P and the secondary air S, with a view to effecting the primary combustion of the solid fuels C and the secondary combustion of the gases G, as explained in detail above for the combustion chamber 10. In particular, the chamber combustion chamber 110 comprises a rear wall 111, a front wall 112, side walls 113 and a grate 114, which are respectively functionally, even structurally, similar to the components 11 to 14 of the combustion chamber 10. In addition, the combustion chamber combustion 110 is associated with an external chute 120 and an evacuation 121, which are respectively similar functionally, even structurally, to the external chute 20 and the evacuation 21.

The combustion plant 101 also includes an intake device 130 which is functionally similar to the intake device 30 of the combustion plant 1. The structure of the intake device 130 differs from that of the intake device 30.

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 grid 114.

As shown schematically in Figure 3, 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 pipe 135, which carries the primary air P and which is common to the various subdivisions, to the casing 133, by opening into the internal volume of this casing 133. The subdivisions 132.1 to 132.3 carry thus respectively primary air veins V1, V2 and V3, which are distinct from each other. Each of these air veins 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 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 control members 134.1 to 134.3 does not limit the invention.

In the example considered in FIG. 3, each of the flow adjustment members 134.1 to 134.5 comprises a register 136, which is arranged inside the corresponding subdivision 132.1 to 132.3 and which is provided 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.

An alternative embodiment for the flow control members 134.1 to 134.3 is illustrated in Figure 4. More specifically, Figure 4 shows an alternative embodiment for the flow control member 134.1, it being understood that this form of alternative embodiment can be applied to other flow control members 134.2 and 134.3. In the embodiment illustrated in FIG. 4, the flow control member 134.1 comprises two flaps 138A and 138B, which are arranged symmetrically inside the subdivision 132.1, each being hinged with respect to this subdivision. . By means of their articulated movement with respect to the subdivision 132.1, the flaps 138A and 138B deviate from or approach each other, 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 4. The symmetry of the arrangement and movements of the flaps 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 rate of the air stream V1 in the subdivision 132.1. In order to control the movement of the flaps 138A and 138B, the flow adjustment member 134.1 comprises an actuator 139, such as a jack, which is connected to the flaps 138A and 138B in an appropriate manner, for example by connecting rods, as shown schematically in Figure 4.

According to an optional arrangement, illustrated by FIG. 3, the air inlet 132 extends substantially horizontally, causing the primary air veins V1 to V3 to flow substantially horizontally in the subdivisions 132.1 at 132.3, until it thus emerges in the internal volume of the casing 133 by laterally crossing this casing. In other words, the casing 133 is not arranged in the vertical extension upwards of the air inlet of the box. In addition, for aeraulic reasons which will appear later, the subdivisions 132.1 to 132.3 of the air inlet 132 are then arranged one above the other: in FIG. 3, the subdivision 132.1 is arranged above subdivision 132.2 which is itself arranged above subdivision 132.3.

Whatever the production specifications of the subdivisions 132.1 to 132.3 of the air inlet 132, the casing 133 is arranged internally to direct the primary air veins 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 advancement Z. primary air veins V1 to V3, once out of the subdivisions 132.1 to 132.3, so that these primary air veins form, at the outlet of the box 131, respective primary air flows P1', P2' and P3', which are sent, below the grid 114, respectively to the regions 114.1 to 114.3 of this grid. Thus, for the combustion installation 101, these primary air flows P1' to P3' are, jointly, functionally similar to the primary air flows P1 to P5 described above in connection with the combustion installation 1.

In the embodiment shown in FIG. 3, the corresponding internal fittings of box 101 comprise plane deflectors 137.1 and 137.2. Each deflector 137.1, 137.2 forms with the vertical an angle comprised between 0 and 20°, which amounts to saying that each of the deflectors 137.1 and 137.2 extends either strictly vertically, or slightly inclined with respect 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. In all cases, this arrangement of the deflectors 137.1 and 137.2 has aeraulic 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, passing from the substantially horizontal flow direction for the primary air streams V1 to V3 to the substantially vertical flow direction for the primary air streams P1' to P3'; on the other hand, the deflectors 137.1 and 137.2 avoid the accumulation of ash which falls on them from the grid 114. in a stepped manner: more precisely, the respective lower ends of the deflectors 137.1 and 137.2 are stepped with respect to one another. In the example considered in Figure 3, 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 housing 133, turned to 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. Of course, the specifics of the staging of the lower ends of the deflectors 137.1 and 137.2 can deviate from what has just been described in connection with the example of FIG. 3. In practice, this staging can be optimized by preliminary numerical fluid mechanics calculations, considering the combustion installation 101 in a nominal operating regime. In all cases, the staggering 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 veins V1 to V3 to respectively direct the latter towards the corresponding regions 114.1 to 114.3 of the grid 114: in the example of FIG. 3, the primary air stream V1 is deflected by the deflector 137.1, the primary air stream V2 escapes the deflector 137.1 but is deflected by the deflector 137.2, and the stream of air V3 escapes from the deflectors 137.1 and 137.2.

Whatever the internal arrangements of the casing 133 making it possible to form the primary air flows P1' and P3' from the primary air streams V1 to V3, these primary air flows P1' to P3' are, as indicated above, respectively associated with the portions 114.1 to 114.3 of the grid 114 and, thereby, respectively associated with corresponding zones Z1' to Z3' of the bed formed by the solid fuels C on the grid 114. Together, these zones Z1' to Z3' of the bed are functionally similar to the zones Z1 to Z5 described above in connection with the combustion installation 1. Advantageously, and taking into account the explanations given previously in connection with the combustion installation 1, 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 combustion for the non-volatile part of these fuels solids, and zone Z3 corresponds to a zone for cooling and finishing combustion for the non-volatile part of the solid fuels.

In the extension of the above considerations, 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 each other: in the example illustrated in Figure 3, subdivision 132.2 is provided with a larger size, of the order of double, than that of the section of each of subdivisions 132.1 and 132.3, because, in the regime of nominal operation for the combustion installation 101, the quantity of primary air to be transported by the subdivision 132.2, whose corresponding stream V2 is associated with the zone Z2, is planned to be of the order of twice that to be transported by each of the subdivisions 132.1 and 132.3, whose corresponding veins V1 and V3 are respectively associated with zones Z1 and Z3.

The combustion installation 101 also comprises a control unit 140 and three pyrometers 150.1, 150.2 and 150.3, which are respectively functionally similar, even structurally identical, to the control unit 40 and to the pyrometers 50.1 to 50.5 of the combustion installation. combustion 1. Thus, taking into account the explanations given previously in connection with the combustion installation 1, it is understood that the pyrometers 150.1 to 150.3 are respectively associated with the zones Z1 to Z3 of the bed of solid fuels C, by measuring the temperature of the primary combustion in, respectively, the zones Z1 to Z3 and by supplying the corresponding temperature measurements to the control unit 140 which, by automatic processing, controls the individual actuation of the flow adjustment members 134.1 to 134.3, each of these flow adjustment members thus being adjusted according to the measurements of the pyrometer associated with the zone to which the primary air stream is sent, the flow rate of which is controlled by this flow adjustment member.

The regulation of the combustion installation 101 is similar to that of the combustion installation 1, so that the regulation of the combustion installation 101 will not be described here in detail, referring to the considerations developed above for regulation of the combustion plant 1.

Whatever the specificities of production and regulation of the combustion installation 101, the latter can bring, in particular compared to the combustion installation 1, economic advantages and compactness. Indeed, instead of using the multiple distinct boxes 31.1 to 31.5, the combustion installation 101 provides only the single box 131 to admit the primary air P under the grid 114, by means of the subdivision of its air inlet 132 and the presence of internal ventilation arrangements of its casing 133, such as the deflectors 137.1 and 137.2, while controlling the spatial and quantitative distribution of the air admitted into the combustion chamber 110. In addition, by arranging the arrival air vent 132 horizontally and by connecting it laterally to the casing 133, the intake device 130 is even more compact, avoiding a costly elevation of the combustion chamber 110 with respect to the supply pipe 135. D Other advantages are deducible from the foregoing by those skilled in the art.

Beyond what has been described so far for combustion plants 1 and 101, various arrangements and variants of these combustion plants and their regulation process can be considered:

- For a given zone of the bed of solid fuels C, among the zones Z1 to Z5 or among the zones Z1' to Z3', more than one pyrometer can be provided. In particular, a pair of pyrometers can thus be associated with at least one of the zones Z1 to Z5 or Z1' to Z3', or even to each of the zones Z1 to Z5 or Z1' to Z3', the two pyrometers of each pair being provided respectively on one and the other of the two side walls 13, typically facing horizontally from each other, which makes it possible to measure the temperature of the primary combustion in the zone concerned from each lateral side of the grid 14. The measurements respectively coming from the various pyrometers for a given zone of the bed are then averaged for the needs of the processing by the control unit 40 or 140.

- Rather than individually adjusting the respective flow rates of the primary air flows P1 to P5 or P1' to P3', provision may be made to regulate the flow rate of the primary air in the supply line 35 or 135, at the means of an ad hoc flow adjustment device, provided on this supply pipe and controlled by the control unit 40 or 140. The regulation of the combustion installation then makes it possible to adjust the total flow of the primary air P passing through the admission device 30 or 130. In this case, a single pyrometer, similar to the pyrometers 50.1 to 50.5 and 150.1 to 150.3, can be used. Of course, several pyrometers can also be used, their respective measurement being averaged for the needs of the processing of the control unit 40 or 140. The total flow rate of the primary air thus regulated is then distributed in the different zones by the flow settings 34.1 to 34.5 or 134.1 to 134.3.

- The number, according to which the bed of solid fuels C is divided into zones and therefore according to which the grid 14 or 114 is divided into regions, may differ from that envisaged for the combustion installations 1 and 101. This being so, this number is preferably at least three in order to include the three main zones corresponding to the successive physico-chemical effects of the primary combustion, namely a drying zone for the solid fuels, a gasification zone for a volatile part of the solid fuels and combustion for a non-volatile part of the solid fuels, and a combustion cooling and finishing zone for the non-volatile part of the solid fuels.

- It can be envisaged to remove the admission of the secondary air S in the combustion installation 1 or 101. In this case, each of the pyrometers 50.1 to 50.5 or 150.1 to 150.3 is preferably located above the grid 14 or 114, at a vertical distance of between 1.5 m and 5 m vis-à-vis this grid.

Whatever the specificities of the process and the combustion installation in accordance with the invention, the advantages provided by this invention, in particular compared to the current techniques mentioned in the introductory part of this document, are numerous.

Thus, 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 can be carried out in real time, or in any case with reaction times much lower than the techniques existing. This very short reaction time is 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 high precision in the dosage of primary air and good control of the ratio between the quantity of air consumed by primary combustion and the quantity of solid fuels burned by primary combustion, and this, advantageously, in different zones of the bed formed by the solid fuels, in particular the three main zones mentioned above. The invention thus makes it possible to provide almost instantaneously and, advantageously, locally the quantity of air just necessary for the primary combustion.

This adjustment "as close 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 plant, to its energy efficiency and to a reduction pollutant emissions. Indeed, by controlling the kinetics of primary combustion, it is possible to control the formation/transformation of many pollutants, such as carbon monoxide, nitrogen oxides and gaseous organic compounds.

The "closer" adjustment of the quantity of primary air also allows temperatures to be controlled throughout the lower part of the combustion chamber. This improves the performance of equipment downstream of the combustion chamber, in particular the production of steam by the boiler exchangers. This also makes it possible to limit the formation, by fusion, 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 simplified, at least by reducing the volume between the grid 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 local temperature peaks which would be excessive and makes it possible to use, for solid fuels with a high calorific value, traditional systems generally limited to solid fuels with a lower calorific value. calorific, such as grids not cooled with water or standard refractory linings, in particular non-nitrided.

Other advantages of the invention have also been mentioned previously or can be deduced from the foregoing by those skilled in the art.

Claims (11)

Method for regulating a combustion plant (1; 101), in which solid fuels (C) are introduced into a combustion chamber (10; 110) and burn there according to primary combustion in the presence of primary air (P ) which is introduced into the combustion chamber with a flow of primary air,
characterized in that the primary combustion of the solid fuels (C) has a temperature which is measured in the combustion chamber (10; 110) by one or more optical pyrometers (50.1 to 50.5; 150.1 to 150.3) which are arranged laterally combustion chamber, and in that the flow of primary air is controlled according to the measurements of the pyrometer(s). Method according to claim 1,
in which the combustion chamber (10; 110) is delimited at the bottom by a grid (14; 114) on which the solid fuels (C) form a bed which is movable in a direction of advance (Z) in the chamber combustion, and
in which the primary air (P) is admitted under the grate, with the primary air flow, before passing through the grate to enter the combustion chamber and reach the bed of solid fuels. Method according to claim 2,
in which the bed of solid fuels (C) is divided into several zones (Z1 to Z5; Z1' to Z3') which follow one another in the direction of advance (Z),
wherein each of the zones is associated with at least one of the pyrometers (50.1 to 50.5; 150.1 to 150.3) so that, for each zone, the pyrometer(s) associated with the zone measure the temperature of the primary combustion of the solid fuels in this area, and
in which the primary air (P) is admitted under the grille (14; 114) being distributed into primary air flows (P1 to P5; P1' to P3') which are respectively associated with the zones so that, for each zone, the primary air flow associated with the zone is sent to this zone with a flow rate which is controlled according to the measurements of the pyrometer(s) associated with this zone. Process according to Claim 3, in which the zones (Z1 to Z5; Z1' to Z3') are at least three in number and include:
- a drying area for solid fuels (C),
- a gasification zone for a volatile part of the solid fuels and a combustion zone for a non-volatile part of the solid fuels, and
- a cooling and combustion finishing zone for the non-volatile part of the solid fuels. Process according to one of Claims 3 or 4,
in which the primary air (P) is admitted under the grille (14) by being distributed by separate boxes (31.1 to 31.5) which are respectively associated with the zones (Z1 to Z5) so that, for each zone, the flow of primary air (P1 to P5) associated with the zone is formed at an air outlet (33.1 to 33.5) of the box associated with this zone while an air inlet (32.1 to 32.5) of the box associated with the zone is provided with a flow control device (34.1 to 34.5), controlled according to the measurements of the pyrometer(s) (50.1 to 50.5) associated with this zone. Method according to one of Claims 3 or 4, in which the primary air (P) is admitted under the grid (114) by a single box (131) which:
- has an air inlet (132) divided into several subdivisions (132.1 to 132.3), which are respectively associated with the zones (Z1' to Z3') and in which flow the respective primary air veins (V1 to V3 ) distinct, each subdivision being provided with a flow control device (134.1 to 134.3), controlled according to the measurements of the pyrometer(s) (150.1 to 150.3) associated with the corresponding zone, and
- is provided with internal fittings (137.1, 137.2) which direct the air streams leaving the air inlet (132), towards the grille (114) to respectively form the primary air flows (P1' to P3'). Process according to any one of Claims 2 to 6,
wherein secondary air (S) is admitted into the combustion chamber (10; 110) above the grate (14; 114) to effect secondary combustion of gases (G) generated by the primary combustion of the fuels solids (C), and
wherein the at least one pyrometer (50.1 to 50.5; 150.1 to 150.3) is located at a vertical distance from the grille, which is between half and two thirds of the distance between the grille and the air intake secondary. Method according to any one of the preceding claims, in which, in order to measure the temperature of the primary combustion of the solid fuels (C), the or each pyrometer (50.1 to 50.5; 150.1 to 150.3) emits at least one bichromatic laser beam in the combustion chamber (10; 110). A method as claimed in any preceding claim, in which, to measure the temperature of the primary combustion of the solid fuels (C), the or each pyrometer (50.1 to 50.5; 150.1 to 150.3) emits into the combustion chamber (10; 110) two laser beams which intersect substantially in the plane of a wall (13) of the combustion chamber, on which the pyrometer is provided. Combustion installation (1; 101), comprising:
- a combustion chamber (10; 110), adapted so that solid fuels (C) are introduced therein and burn therein according to primary combustion in the presence of primary air (P), and
- an intake device (30; 130), suitable for supplying the combustion chamber with primary air according to a primary air flow,
characterized in that the combustion installation further comprises:
- one or more optical pyrometers (50.1 to 50.5; 150.1 to 150.3), which are arranged laterally to the combustion chamber (10; 110) and which are suitable for measuring a temperature of the primary combustion in the combustion chamber, and
- regulating means (34.1 to 34.5, 40; 134.1 to 134.3, 140) suitable for, from the measurements of the pyrometer(s), controlling the flow of primary air from the intake device (30; 130). Combustion plant according to Claim 10,
in which the combustion installation (1; 101) further comprises a grate (14; 114):
- which delimits the combustion chamber (10; 110) downwards,
- which is adapted to support a bed which is formed by the solid fuels (C) and which is movable in a direction of advance (Z) in the combustion chamber, and
- under which the intake device (30; 130) opens out so that the primary air (P) supplied by the intake device according to the primary air flow enters the combustion chamber by crossing the grid,
in which the intake device (30; 130) is suitable both for distributing the primary air into primary air flows (P1 to P5; P1' to P3'), and for sending these flows of primary air respectively to associated regions (14.1 to 14.5; 114.1 to 114.3) of the grid, which follow one another in the direction of advance (Z), and
in which the regulation means (34.1 to 34.5, 40; 134.1 to 134.3, 140) are adapted to control the flow rate of each of the primary air flows (P1 to P5; P1' to P3') from the measurements of the or pyrometers (50.1 to 50.5; 150.1 to 150.3) measuring the primary combustion temperature of a zone (Z1 to Z5; Z1' to Z3') of the bed, which is supported by the region of the grid, towards which the device intake sends primary airflow.