FI94170C - Fluidized bed boiler with internal circulation and method for controlling this - Google Patents

Abstract

An internal circulation type fluidized bed boiler in which a fluidized bed primary combustion chamber is formed by providing above the portion of an air distributing plate from which the air having a higher mass velocity is ejected an inclined partition wall which is adapted to intercept an upward flow of the fluidization air ejected from this air ejection portion, and turn this upward flow of the air toward the position above the portion of the air distributing plate from which a gas having a low mass velocity is ejected, with a heat recovery chamber formed between the inclined partition wall and a furnace wall. The inclined partition wall is formed so as to have an angle of inclination of 10 DEG -60 DEG with respect to a horizontal plane, and a horizontal projection length of 1/6-1/2 of the horizontal length of the furnace bottom. The method of controlling this fluidized bed boiler consists of the steps of controlling the quantity of heat recovered from the heat recovery chamber in compliance with the request by the users of recovered heat by suitably regulating the flow rate of the air ejected from a diffuser for the heat recovery chamber, and controlling the feed rate of the fuel supplied to the fluidized bed primary combustion chamber, on the basis of the temperature of the fluidized bed primary combustion chamber.

Description

94170

Fluidized bed boiler with internal circulation and method for controlling this

The present invention relates to an apparatus for the incineration of coal, anthracite, coal concentrate, petroleum coke, bark, bagasse, industrial waste, municipal waste and other combustible substances using the so-called a circulating fluidized bed, and for recovering thermal energy from said fluidized bed, and a method for controlling the amount of diffusion gas blown into the thermal energy chamber and the amount of recovered thermal energy and maintaining a constant temperature in the primary combustion chamber of the fluidized bed.

A kiln with a rotating fluidized bed 15 is previously known, which is described, for example, in Japanese Patent Publication Nos. 46988/76 and 5242/68.

An example of the above-mentioned circulating type fluidized bed incinerator will be described with reference to Fig. 1. A diffuser plate 2 is placed on the bottom of the incinerator 1 for the fluidization of the fluidization medium. The diffuser plate 2 is arranged at an angle so that its side wall provided with the waste supply device 3 is higher than the opposite side, the lower part of this opposite side being connected in pieces. 25 for carpet material outlet 4.

The fluidizing air supplied from the fan 8 is blown upwards from the diffuser plate 2 through the air chambers 5, 6 and 7 for the fluidization of the fluidizing medium.

The mass flow of fluidizing air 30 blown from each air chamber is sufficient to form a fluidized bed, with the flow blown from chamber 7 being the largest and the flow blowing from chamber 5 being the smallest.

The amount of mass flow is selected, for example, so that the mass flow blown from the air chamber 7 is 4-20 Gmf, or preferably 6-12 Gmf, the mass flow blown from the air chamber 2 94170 6 is 3-10 Gmf, or preferably 4-6 Gmf, and the chamber 5 is blown air flow 1-4 Gmf, preferably 1 - 2.5 Gmf.

1 Gmf denotes the mass flow by which the fluid-5 dation is initiated.

The state of the fluidizing medium changes from a static state called a static layer to a dynamic state called a fluidized bed, the above-mentioned value being a threshold value between the two states.

Although Figure 1 shows three air chambers, the number of these air chambers is alternative and the mass flow of fluidizing air is made large for the chamber close to the outlet 4 and small for the chamber remote from this outlet.

Just above the air chambers 7 and 6, an inclined wall 9 is placed, which acts as a deflection wall to interrupt the flow of fluidizing air flowing upwards, so that the air is led towards the supply device 3 of combustible materials 20.

An inclined surface 10 is formed above the inclined wall 9, the inclination of which is opposite to the inclination of the wall 9 in order to prevent the accumulation of the fluid medium on it.

The inclination of the diffuser plate is when non-combustible substances are contained in the combustible materials to be removed, preferably of the order of 5 to 15 °; however, when the amount of these non-combustible materials is small, the slope may be non-existent and the plate may be horizontal because the fluidizing medium can be circulated by adjusting the flow rate of air blown from the respective air chambers.

The surface of the wall 9 can be either flat, convex or concave. A flue gas outlet line 12, a supply line 13 for supplying waste liquid generated during the operation of the incinerator 35, and a cooling water supply line 14, etc. are placed in the ceiling 11 of the incinerator.

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During the operation of the incinerator 1, the fluidizing air is supplied to it by means of a fan 8 and sprayed in regular mass flow rates, which decrease according to the successive order of the chambers 7, 6 and 5.

5 In a conventional fluidized bed, the fluidizing medium moves strongly up and down like boiling water to reach a fluidized state. However, the fluidizing medium in the portion near the side wall provided with the combustible material supply device 3 does not move strongly up and down 10, instead forming a moving layer 15 with poor fluidization. The width of this moving bed is small at its lower part due to the difference in mass flow of air sprayed from the respective air chambers. This means that the rear end of said movable layer 15 extends over the air chambers 6 and 7 and thus the fluidizing medium is blown upwards in a large mass flow from these chambers, moving away from them, whereby the part on top of the movable layer 15 descends by gravity. In connection with such a downward movement of the layer 15 20, a fluidizing layer is added to the fluidizing medium following the circulating flow 16 towards the top of the layer 15, and when the above-mentioned operation is repeated in its entirety, a circulating fluidized bed is formed.

The fluidizing medium transferred to the air chambers 6 and 7 is blown upwards towards the inclined wall 9, where it is deflected and rotatably moved towards the side wall equipped with a combustible material feeder, this medium flow descending to the top of the moving layer 15 and then again. is blown into circulation after it has reached the rear end of said layer.

The combustible materials fed from the feeder 3 to the upper part of the movable layer 15 in the incinerator 1, which are in the state 35 described above, follow the descending movable layer 15 moving downwards.

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In a conventional fluidized bed, paper-like combustible materials that are light in weight and contain a lot of exothermic energy are fired on the surface of the fluidized bed alone without heating much of the fluidizing medium. However, such wastage is prevented in a circulating fluidized bed in which these combustible materials are safely combusted in the descending moving bed 15 and the circulating fluidized bed 16, thus allowing efficient heating of these combustible materials to the fluidizing medium.

The non-combustible materials removed together with the combustible materials first settle inside the descending moving bed 15, then move laterally, whereby during this movement the combustible materials (e.g. electrical conductor coatings) attached to said combustion-15 towers and fixedly connected to the materials are burned. The non-combustible materials entering the rear end of the bed are fed to the non-combustible material outlet 4 via a lateral movement of the fluid medium 20 and the inclination of the air diffuser plate 2, passing through the vertical passage 17 and the non-combustible

: 25 The sorted or fresh fluid is fed to the “incinerator 1 by means of a conveying device 20, such as a hoist.

Another example of a conventional fluidized bed type incinerator 30 will be described below with reference to Fig. 2.

As shown in Fig. 2, a diffuser plate 22 for fluidizing air is placed in the inner bottom portion of the incinerator.

The opposite edge portions of this air diffuser plate 22 are set lower than its central portion, said diffuser plate 35 being formed in a brush-like cross-section I »H i III! I! ! 81-94170 5 ("Nazi-like") approximately symmetrically with respect to the centerline 42 of the incinerator, the non-combustible outlet 24 being connected to each of the opposite edge portions.

The fluidizing air supplied from the fan 28 is sprayed upwards from the air diffuser plate 22 through the air chambers 25, 26 and 27. The mass flow of fluidizing air sprayed from the opposite air portions of each of the air chambers 25 and 27 is large enough to form a fluidized bed, however, the mass flow of the fluidized air sprayed from the central air chamber 26 is smaller.

For example, the mass flow of fluidizing air sprayed from air chambers 25 and 27 is selected to be 4-20 Gmf, preferably between 6-12 Gmf, while the fluidizing air sprayed from air chamber 26 is selected to be 0.5-3 Gmf, preferably between 1-2.5 Gmf. .

The number of air chambers can be selected from three or more. With a number greater than three, the mass flow of fluidizing air is made small in the chambers near the center and large in the chambers near the opposite edge portions.

Just above the air chambers 25 and 27, sloping walls 29 are formed in the opposite edge portions as deflection walls to disturb and direct the fluid flow towards the center of the incinerator.

. Above the inclined walls 29, inclined surfaces 30 are placed, the inclination of which is opposite to the inclination of the walls 29, to prevent the accumulation of the fluid medium thereon.

The slope of the diffuser plate 22 is preferably of the order of magnitude of 5 to 15 ° when non-combustible materials are associated with the combustible materials.

This slope is not required when no non-combustible materials are associated with the combustible materials.

The surface of the inclined walls 29 can be either flat, convex or concave.

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A combustible material outlet 34 in the opposite direction to the central air chamber 26, as well as an exhaust gas outlet 32, is formed in the roof portion 31 inside the incinerator in communication with the outlet 33 of the combustible material supply device 23.

The inclined wall 29 can be made as a wall structure comprising metal wires through which the fluidizing air passes for preheating.

In connection with the operation of this incinerator, the fluidizing air 10 is fed to it from the fan 28, and the air is sprayed as a high mass flow from the air chambers 25 and 27 and a low mass flow from the air chamber 26.

In a conventional fluidized bed, the fluidizing medium moves strongly up and down like boiling water to form a fluidizing state; however, in the case shown in Figure 2, the fluidizing medium above the air chamber 26 does not make this strong upward movement, but forms a moving layer with poor fluidization. This movable layer is narrow at its top, spreading 20 outwards laterally at opposite ends towards the portions of the fluidized beds, with the portion of the movable layer coming on top of the air chambers 25 and 27 being blown upwards, subjecting the fluidizing medium to a large mass flow of fluidized air. Thus part. The fluidizing medium at the rear end 25 moves upwards therefrom, whereby the layer just above the air chamber 26 descends under the effect of gravity. Above this moving bed, as mentioned above, material from the fluidized bed 30 is added to the fluidized bed following the circulating flow 36. In view of the above, a certain portion of the fluidizing medium above the air chamber 26 is formed into a mass which forms a gradually descending and dispersing moving layer 35.

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The fluid medium transferred above the air chambers 25 and 27 is blown upwards against the inclined walls 29, where its direction is deflected and rotated in an upward direction 5 towards the kiln, however, due to a sudden increase in the cross-sectional area of the kiln, it loses its upward downward velocity. 35 for moving on and gradually descending, again being blown up for the rotational movement 10 after entering the rear end of the moving bed. A portion of the fluid medium circulates as circulating streams in the 36 fluidized bed.

When the combustible materials are removed from the combustible material outlet 34 of the incinerator in the fluidization state 15 described above, these combustible materials fall on the descending moving bed 35. Because the fluidizing fluid near the top of the moving bed behaves to flow toward the center away from the sides, the combustible materials follow these flows 20 and come on top of the descending moving bed 35. Thus, lightweight materials, such as papers, will certainly follow the downwardly descending moving layer 35 and will be prevented from burning solely on top of the conventional fluidized bed, thereby not heating the fluidization medium. Instead, they are safely combusted within the descending moving bed 35 and the circulating streams 36, thereby effectively heating the fluid medium. The heat of the combustible materials is partially dissipated within the moving bed 35 to form a combustible gas. In this case, since the resulting combustible gas spreads horizontally as the fluidizing medium descends and disperses and becomes combusted within the fluidized bed, the exothermic energy caused by the combustion of the gas effectively heats the fluidizing medium.

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Even when heavy and large materials such as bottles and pieces of metal or the like are removed from the surface of the descending layer 35, they do not immediately fall onto the air chamber 26 but gradually descend through the downwardly moving layer 35 towards the non-combustible material outlet 24 together with the fluid medium flows.

Thus, relatively large combustible materials are dried, gassed, or burned within the downwardly moving moving bed 35 during a gradual downward movement, and are burned to an almost completely small size by the time they reach the rear end of the moving bed without interfering with the formation of the fluidized bed. .

Thus, it is not necessary to pre-tear the combustible materials into pieces by means of a tearing device, but it is sufficient to break the sacks containing the combustible materials by means of the combustible material supply device 23. Thus, the tearing device or step can be omitted, which simplifies the hardware.

The combustible materials removed to the descending moving bed 35 are dispersed in the fluidizing medium and thus the combustion efficiency is increased.

Medium-sized non-combustible materials fed through the combustible material feeder 23 first move downward and sideways within the descending moving bed 35, and during this movement combustible materials (e.g., electrical conductor coatings) attached to or bonded to these non-combustible materials become burned. The non-combustible materials entering the rear end are fed to the non-combustible material outlets 24 via the lateral movement of the fluid medium and the diffuser plate 22 and are discharged through the vertical passages 37.

The non-combustible materials are then fed through a conveyor 38 to a screen (not shown) and the fluidization medium is sorted.

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In the circulating type Lei bed incinerator shown in Figures 1 and 2, the fluidizing medium comprises solid granules generally about 1 mm in size, and the incinerator is operated at a fluidization medium temperature of 500 to 800 ° C, with an exhaust gas temperature of 750 to 950 ° C.

The exhaust gas is cooled to approximately 300 ° C by means of a gas cooling chamber or air preheater, and the gas is removed through a chimney after removal of small components or heat recovery from the exhaust gas outlet by means of through which more and more thermal energy is recovered, 15 or the gas is cooled in connection with dust extraction.

When the exothermic energy of the combustible materials is high and the fluidizing medium is heated above a predetermined temperature, for example above 800 ° C, it is possible to sinter the fluidizing medium to render the Lei-20 layer ineffective if the combustible substances contain alkali metal alloys. In such cases, it has been customary to lower the temperature of the fluidizing medium to a predetermined temperature by spraying water on the medium.

• 25 Attention has thus been drawn to cases in which: in which the thermal energy contained in the fluidizing medium is recovered by placing thermally conductive lines inside the fluidizing medium; however, there are several problems if several thermally conductive conductors are placed in the fluidized bed because fluidization is prevented by: non-combustible substances and the fluidizing medium rubs against the thermally conductive conductors, and a heat recovery operation must always be performed to protect the conductive conductors even when 35 Poor energy recovery is not required. These disadvantages have thus occurred in practice.

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On the other hand, in the case of a conventional fluidized bed type digester, there are two apparatus arrangements which can be distinguished by considering the arrangement comprising the combustion of a thermally conductive part and non-combustible combustible materials dispersed in a fluidized bed as follows: (1) and a 10 (2) recycled fluidized bed digester.

In the type of cooker without recirculation, the thermally conductive lines are placed inside the fluidized bed and the heat transfer is performed in a very efficient manner between these lines, the high temperature combustible fuels and the fluidizing medium. In the type of recirculated digester, some of the small combustible material particles that have not yet burned and the ash or fluidization medium (recirculating solid material) merge into the flue gas flow and travel independently toward the return portion of the heat transfer furnace. after this heat transfer to the combustion furnace together with a part of the combustion gas, the type of digester 25 being called by the name according to the recirculation process described above.

(3) Fluidized bed digester with internal circulation

The fluidized bed incinerator used in connection with the fluidized bed digester with an internal circulation, equipped with a deflection structure projecting from the wall of the furnace 30 to assist in the recycling of the fluidizing medium, and a non-fluidizing heat energy recovery chamber between the furnace walls is described in U.K. in Patent Publication No. 1604314. However, the transfer of the fluidizing medium from the thermal energy recovery chamber to the furnace chamber of the fluidized bed furnace described in this specification is with the fuel fed.

In a vortex sintering type, several fuels with different characteristics can be burned according to a special combustion process, however, many disadvantages have recently been observed. The load capacity of the bubbling type 10, the complexity of the fuel supply system, the large amount of quicklime required for denitration and the abrasion of the thermally conductive wires, etc. However, it has not yet been technically possible to solve the problems associated with maintaining suitable temperatures in a recirculation system containing an incinerator and a cyclone, descaling the digester-20, and a long time requiring a cold start.

The applicants of this patent application have studied the above-mentioned problems in order to find suitable solutions to them, and have found the following measures to be effective. In a circulating fluidized bed incinerator, a sloping partition is used inside the furnace wall and above the end portion of the diffuser plate instead of the sloping wall forming the primary combustion chamber of the fluidized bed, the heat recovery chamber also being located on the rear sides or two of the sloping partition wall. between the two inclined partitions so that the recovery chamber communicates at the top and bottom with the primary combustion chamber of the fluidized bed, the thermally conductive lines arranged to pass the heating medium 35 through the heat recovery unit along the back of the partition. The heated fluidization medium fed to the thermal energy recovery chamber over the sloping septum 5 is under the influence of a fluidizing gas blown from the diffuser and is dispensed in an amount of 0-3 Gmf or preferably 0-2 Gmf of fluid medium to form a static or descending fluid energy layer, through conductive wires. The inventors have found that the above arrangement makes it possible to easily control the temperature of the primary combustion chamber of the fluidized bed in the above-mentioned incinerator while efficiently recovering thermal energy via heat conducting lines in a fluidized zone with low degree of abrasion of heat conducting lines.

The present inventors have researched and further developed a circulating fluidized bed type furnace equipped with a thermal energy recovery chamber 20 connected to a sloping inner wall, as well as a method for recovering thermal energy and controlling the fuel feed rate, and found in the intake chamber, by adjusting the inclination of the inclined partition to 10 to 60 ° or preferably 25 to 45 ° with respect to the horizontal plane, and by selecting the extent of the inclined partition in the horizontal direction at the bottom of the kiln to 1/6 to 1/2 or preferably 1/4 to 1/2 calculated from the horizontal length of the scale 30 of the bottom of the incinerator. The inventors have also found that in addition to fully meeting the requirements of recovered heat users, limiting the degree of temperature variation in the primary chamber to a small area by controlling the amount of heat recovered from the heat recovery chamber 13 94170 etc. by controlling the temperature, etc. while controlling the amount of air blown from the diffuser to control the settling rate of the fluid medium in the thermal energy recovery chamber according to varying user requirements such as steam pressure and temperature and the amount of fuel fed by these users. requirements or based on the primary to its chamber temperature.

The present invention therefore relates to a fluidized bed waste boiler comprising: an incinerator comprising a primary fluidized bed, air diffuser means and a sloping wall arranged above the diffuser means, the diffuser means producing an upward mass flow greater on at least one side than the other side; comprising heat exchange surface means for the passage of a fluid medium, the heat energy recovery chamber further comprising a heat energy recovery layer and additional diffuser means, said inclined wall being an inclined partition separating the primary fluidized bed from the thermal energy recovery layer from the upper and lower ends of the inclined partition wall, whereby part of the medium can be led to the thermal energy recovery chamber 30 through the inclined partition wall; above the top, • · the amount of medium gas fed from the additional diffuser means to the heat recovery chamber causes the medium in the recovery chamber to settle in the state of the moving medium layer, • · 14 94170 with the inclined partition inclined 10-60 ° to the horizontal. The fluidized bed boiler according to the invention is characterized in that the inclined partition wall is shaped so that its horizontal projection length is 1/6 to 1/2 of the horizontal length of the bottom of the incinerator.

The invention further relates to a method for controlling a fluidized bed waste boiler, the boiler comprising: an incinerator comprising a primary fluidized bed and air diffuser means, a thermal energy recovery chamber having a thermal energy recovery layer and additional diffuser means, a sloping partition separating the primary fluidized bed separating the primary fluid and the thermal energy recovery layer communicating with the upper and lower ends, heat exchange surface means adapted to the thermal energy recovery layer for passing the fluid, and wherein: an ascending layer is formed at the partition wall and a descending layer is formed opposite the inclined partition wall, whereby 25 ascending and descending layers m form a circulating layer, the medium gas supplied by the diffuser means is directed to the area of the inclined partition wall, the mass flow being such that a part of the circulating layer medium rises upwards to the thermal energy recovery chamber. The control method according to the invention is characterized in that the fuel supply stage is controlled in the method.

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Preferred embodiments of the fluidized bed boiler and control method according to the invention appear from the appended dependent claims 2 to 4 and 6.

Figures 1 and 2 show sectional views showing 5 a conventional circulating type fluidized bed incinerator; Fig. 3 schematically shows a principle according to the present invention; Fig. 4 shows a sectional view of a fluidized bed digester with internal recirculation, showing in general terms its structure according to the present invention; Fig. 5 is a graphical representation of the relationship between the amount of fluidizing air (Gmf) in the portion below the sloping septum in the primary fluidized bed combustion chamber and the amount of recycled fluidizing medium; Fig. 6 shows graphically the relationship between the amount of diffusion air (Gmf) in the heat energy recovery chamber and the rate of settling of the downwardly moving bed in this chamber; Fig. 7 shows graphically the relationship between the fluidization mass flow (Gmf) and the total heat-conductivity coefficient in a conventional bubble cooker; Fig. 8 shows graphically the relationship between the diffusion mass flow (Gmf) in the heat recovery art chamber and the total thermal conductivity layer present in a fluidized bed digester with internal recirculation according to the present invention. Fig. 9 shows graphically the relationship between the fluidization mass flow and the abrasion rate of the thermally conductive line; Figures 10 and 11 show changes in fuel feed rate, vapor pressure, and fluidized bed temperature over time with the fluid mass flow for the heat energy recovery chamber 30 adjusted according to a stepwise change in vapor flow rate; Fig. 12 shows similar changes over time with a one-time change in steam flow rate; Figs. 13 and 14 show 35 sectional views showing embodiments of a fluidized bed mold with internal recirculation according to the present invention; Fig. 15 shows a sectional side view of a fluidized bed digester with internal recycling, showing another embodiment of the present invention which is particularly well suited for use as a small digester; Fig. 16 is a plan view of a section of the embodiment of Fig. 15 taken in the direction of arrows A to A, showing in particular a fluidized bed digester with internal recycling used as a circular digester; and Figures 17 to 19 show fluidization patterns in the primary fluidized bed combustion chamber showing the relationship between the horizontal length L of the bottom of the incinerator and the horizontal dimension 1 of the inclined partition.

The present invention will now be described with reference to the accompanying drawings.

The diffuser plate 52 shown in Figure 3 is positioned at the bottom of the incinerator 51 to direct the fluidizing air supplied by the fan 57 through the fluidizing air supply line 53 20, the diffuser plate 52 being made approximately symmetrically bristle ("nasal") about the furnace centerline. The fluidizing air supplied from the fan 57 is sprayed upward from the air diffusion plate 25 52 through the air chambers 54, 55 and 56, the fluid flow of fluidizing air sprayed from the air chambers 54 and 56 at opposite ends sufficient to form a fluidized bed of fluidized bed reduced without. as described above in connection with previously known application examples.

The inclined partitions 58 are placed above the air chambers 54 and 56 at opposite ends as transverse walls intended to interfere with the air flow upwards and to direct the air to flow towards the center of the kiln, thereby creating circulating currents in the direction of the arrows. due to the mass flow of sprayed fluidizing air. On the other hand, thermal energy recovery chambers 59 are formed between the rear side surfaces of the inclined partitions 59 and the side walls of the incinerator to conduct a portion of the fluidization medium over the upper ends of the inclined side walls 58 during operation.

In the context of the present invention, the inclined part of the inclined partition wall is set at an inclination of 10 to 60 °, or preferably 25 to 45 ° with respect to the horizontal plane, its extent 1 in the horizontal direction with respect to the bottom of the furnace device being 1/6 to 1/2, or preferably 1/4 - 1/2 of the horizontal length L of the bottom of the incinerator.

The angle of inclination of the inclined sidewall with respect to the horizontal plane and the extent of the horizontal direction are both factors influencing the fluidization state of the fluidizing medium in the primary fluidized bed combustion chamber, also affecting the amount of granules fed to the thermal energy recovery chambers. The effect of dimensions "L" and "1" and the flow patterns of the fluid medium are shown in Figure 17.

When the angle of inclination of the inclined part is less than 25 10 ° and greater than 60 ° with respect to the horizontal plane, • satisfactory circulating flow is not achieved and the conditions under which the fuel is burned deteriorate. This angle is preferably between 25 and 45 ° and can be set particularly advantageously to 35 °.

When the inclination of the inclined partition portion 1 in the horizontal direction with respect to the bottom of the kiln is more than 1/2 of the length L of the kiln bottom, as shown in Fig. 18, the amount of fluidized fluid deviated from the inclined partitions and falling into the center of the kiln becomes smaller, thus adversely affecting the formation of the moving bed. in the central part of the kiln and also in the manner of landing and dispersing of the fuel fed to the central part of the kiln.

On the other hand, in a situation similar to that shown in Fig. 19, where the inclination of the inclined partition 1 with respect to the furnace bottom 1 is less than 1/6 of the furnace bottom length L, circulating current formation also adversely, when the deflected flow of the fluid medium into the recovery chamber becomes insufficient.

A diffuser device 15 is provided in the lower part of the heat energy recovery chamber 59 and on the rear side of the inclined partition 58 for the heat energy recovery chamber to conduct gas, such as air, from the fan 60 through the supply line 61. An opening 63 is formed in a portion 63 of the heat recovery chamber 59 near the setting point of the diffuser 62, whereby the fluidizing medium introduced into the heat recovery chamber 59 20 is continuously or intermittently deposited with the moving bed to be formed depending on the mode of use.

Figure 4 shows an embodiment based on the principle of Figure 3.

The descending amount of the fluidizing medium for recirculation in the thermal energy recovery chamber is controlled by the amount of diffusion air for the thermal energy recovery chamber and the amount of fluidizing air for the combustion section. This means that the amount of fluidizing medium (G1) fed to the thermal energy recovery chamber increases as shown in Figure 5 as the amount of fluidizing air 94470 19 sprayed from the diffuser plate 52, especially from the terminal chambers 54 and 56, increases to cause fluidization in the combustion section. Further, as shown in Fig. 6, the amount of fluidizing medium landing in the heat recovery chamber changes approximately directly proportional to the change in the amount of diffusion air blown into the heat recovery chamber when this change is of the order of 0 to 1 Gmf, becoming approximately constant if the heat recovery to a value greater than 1 Gmf. This constant amount of fluidization medium is almost the same as the amount of fluidization medium (G1) fed to the thermal energy recovery chamber, and thus the amount of fluidization medium descending in the thermal energy recovery chamber becomes a value corresponding to G1. By controlling the amount of air for both the combustion section and the recovery chamber, the descending amount of fluid in the heat recovery chamber 59 can be adjusted.

The settling rate of the fluid medium in the static bed, on the order of 0-1 Gmf, is due to a difference in weight of the fluid medium (fluid bed height difference) between the thermal energy recovery chamber and the primary fluidized bed combustion chamber. Fluid recirculation is aided by a deflection flow in which a sufficient amount of fluid is passed through a sloping septum.

The relationship between the height of the fluidized bed and the amount of fluidized bed recirculation (descending flow) is described in detail below.

In the case where the surface of the fluidized bed is lower than the upper end of the inclined septum, the upwardly moving air flow along its inclined septum is sprayed along the inclined septum 35 from the fluidized bed followed by the fluidizing medium.

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The sprayed air flow is brought into a different state compared to the fluidized bed and released from the fluidizing fluid with which the fluidized bed is filled, the cross-sectional area of the airflow passage suddenly expanding, dispersing the sprayed airflow and decreasing its velocity to a few meters per second. removed in the upward direction. Thus, the fluidizing medium following the sprayed air flow loses its kinetic energy, falling down under the influence of gravity, whereby friction occurs in the exhaust gas when the grain size of the fluidizing fluid accompanying the air flow is too large (about 1 mm).

When the surface of the fluidized bed is above the upper end of the inclined bulkhead, a portion of the fluidizing medium collected by the bulkheads is sprayed along the deflection bulkhead in a direction determined in the same manner as a rotary fluidized bed incinerator. above the upper end of the sloping septum, falling all around. Thus, a portion of the fluid medium is fed in a large amount from the back side of the septum, i. per heat recovery chamber.

Thus, the direction of movement 25 of the sprayed fluidization medium approaches the vertical direction as the surface becomes higher above the upper end of the inclined septum. The amount of fluidizing medium fed to the heat energy recovery chamber thus becomes large when said surface is slightly above the upper end of the inclined partition.

Figure 5 shows the relationship between the amount of fluidizing air in the primary fluidized bed combustion chamber in the portion below the sloping septum and the amount of fluidizing medium recycled through the thermal energy recovery chamber.

35 For example, during an operation under space Lx, if the height of the fluidized bed decreases due to the dispersion of the abrasion fluid, the amount of fluidized medium recycled is suddenly reduced to, for example, less than 1/10 of the previous amount and thermal energy cannot be recovered. Thus, the amount of fluidizing air 5 is important, and if it is set above 4 Gmf and preferably above 6 Gmf, the value of the ratio Gj / G ,, remains greater than 1, so that the required and sufficient amount of recyclable fluidizing medium can be obtained even when the fluidized bed height changes. .

Further, by adjusting the air mass flow sprayed from the diffuser at the bottom of the thermal energy recovery chamber to 0-3 Gmf, or preferably 0-2 Gmf, and the mass flow of fluidized air sprayed from the diffuser plate placed below the inclined septum to 4-15 20 Gmf, or Gmf, i.e. always keeping said mass flow higher on the combustion chamber side than on the thermal energy recovery chamber side, the amount of fluidizing medium 20 fed from the thermal energy recovery chamber back to the primary fluidized bed combustion chamber can be sufficiently ensured.

The moving bed in the thermal energy recovery chamber is theoretically called a static layer when the mass flow is 0 to 1 Gmf, and a fluidized bed with a mass flow greater than 1 25 Gmf, and it is well known that a minimum mass flow of 2 Gmf is required for a solid fluidized bed. On the other hand, in the case of a moving bed according to the present invention which always moves and descends downwards, this descending layer is satisfactorily formed until the mass flow increases to about 1.5 to 2 Gmf without the mobile layer being destroyed by the bubbling phenomenon. In this case, it is assumed that the granules of the fluidizing medium gradually settle downwards and move in an oscillating manner, whereby the fluidizing air is converted into small air bubbles which flow uniformly upwards towards the top of the moving bed.

22 94170 Inside the heat energy recovery chamber 59, thermally conductive lines 65 are inserted, through which a flowing heat sink medium, such as steam or water, etc., passes, whereby heat energy is recovered from the fluidization medium 5 by causing heat transfer in the heat energy recovery chamber. The thermal conductivity coefficient of the thermal energy recovery section varies greatly, as shown in Fig. 8, as the amount of diffusion air in the thermal energy recovery chamber 10 varies between 0 and 2 Gmf.

The load-dependent properties caused by the moving layer formed in the thermal energy recovery chamber are described below.

The relationship between the total thermal conductivity coefficient and the fluid flow of the fluidizing mass-15 is shown in Figure 7. With a mass flow value between 0 and 1 Gmf, the increase in the thermal conductivity layer is small, increasing abruptly when the mass flow exceeds 1 Gmf. As a method for changing the operation of a fluidized bed digester using the above 20 phenomena, DOE Report, 6021 (2), 655-633 (1985) describes a "wing panel type" in which the thermal conductivity coefficient responsive to a change in fluidized mass flow is found to be insensitive (static layer) or hypersensitive (fluidized bed).

25 Looking at some foreign patents, a number of cases can be found which appear to be similar to the present technology in that the combustion chamber and the thermal energy recovery chamber are spaced apart; however, all of the partitions described herein are arranged vertically, with the fluidizing medium in the thermal energy recovery chamber being convertible to a static layer and a fluidized bed, having a small amount of thermal energy recovered as a static layer, and up to a large amount of recovered at the bottom. This is because it is difficult to obtain a deflected flow in connection with a vertical partition as compared with the case where the partition is inclined. In the case of a vertical partition, it is thus necessary for the fluidizing medium to be arranged in a fluidized state (which is similar to water) in both the combustion and heat energy recovery chambers, whereby the fluidizing fluid is made to flow between the two chambers.

The relationship between the total thermal conductivity coefficient and the mass flow for fluidization is shown in Figure 8. As shown in Figure 8, this ratio changes almost linearly and thus the amount of thermal energy recovered and the temperature of the primary fluidized bed combustion chamber 15 can alternatively be monitored. In addition, such monitoring can be performed easily and simply by adjusting the amount of diffusion air in the heat energy recovery chamber.

It is also said that the abrasion rate of the thermally conductive lines 20 in the fluidized bed is directly proportional to the third power of the mass flow for fluidization, as shown in Figure 9. Thus, the abrasion problem of the thermally conductive lines can be solved by adjusting the thermal energy recovery chamber. The amount of diffusion air blown into the moving bed in the die is 0-3 Gmf, or preferably 0-2 Gmf.

To control the amount of recovered thermal energy, the amount of recycled fluidization medium is adjusted, as described above, while also adjusting the thermal conductivity factor. In this case, if the amount of fluidizing gas in the air chambers 54 and 56 for the primary fluidized bed incinerator is kept constant and the amount of diffusion air in the thermal energy recovery chamber is increased, the amount of recycled fluidization medium . From the point of view of the fluidizing medium in the fluidized bed, the above corresponds to the effect obtained by preventing the temperature of the fluidizing medium from rising above a predetermined temperature.

A variety of devices can be used to introduce the diffusion gas into the heat recovery chamber 59, but are generally positioned so as to be in an inclined position along the rear side of the sloping septum (opposite the heat recovery chamber) for efficient use of the heat recovery chamber.

The openings in the diffuser for supplying diffusion air 15 are also made smaller as their position approaches the tip end of the diffuser (as the bed height decreases), whereby the spraying of large amounts of diffusion air in the tip end part is prevented.

The corresponding sizes of the orifices are preferably determined so that an approximately uniform amount of diffusion is sprayed over the entire length of the diffuser device 52, this amount of diffusion air being 2 Gmf. This means that when the above conditions are met, it is possible to achieve the maximum amount of thermal energy recovered by all the thermally conductive surfaces in the thermal energy recovery chamber, and the abrasion rate of these thermally conductive surfaces can be kept low on all surfaces.

In Fig. 4, the combustible material feeder 66 at the top of the incinerator 51 and 67 comprises a steam drum which forms a recirculation passage (not shown) together with the heat conducting lines 65 in the heat energy recovery chambers 59. Numeral 69 denotes non-combustible exhaust passages connected to opposite ends of the air diffuser plate 52 at the bottom of the incinerator 51, and numeral 70 denotes a screw conveyor with screws 71, each screw 71 having a helical line opposite each other. The location of the combustible material feeder is practically not limited to the top of the digester, but can also be placed on the side of the digester as a spreader 66 'for feeding coal, etc. through it.

The combustible materials F fed through the combustible material feeder 66 or 66 'are recycled and polished in a fluidizing medium which circulates under the influence of the circulating current caused by the fluidizing air. In this case, the fluidizing medium on the air chamber 55 in the upper central part does not follow its strong upward movement, but forms a descending moving layer which is in a weak fluidization state. This movable layer is narrow at its top and its rear ends extend in opposite directions to reach the portions above the air chambers 54 and 56 at opposite side ends, subjecting it to a higher mass flow of fluidized air sprayed from both air chambers and blown upwards. Thus, a portion of each rear end moves and the layer just above the air chamber 55 descends under gravity. Fluidization medium accumulates above this layer after receiving additional material from the fluidized bed, as will be described later, with the fluidization medium above the air chamber 55 forming a gradually and continuously descending moving layer upon repeating the above procedures.

The fluidizing fluid transferred above the air chambers 54 and 56 is blown upward, deflected and swirled by the inclined partitions 58 to flow towards the center of the incinerator 51 as it falls onto the central moving bed, after which it is recirculated as described above. as it is conducted to the thermal energy recovery chambers 59 over the tops of the inclined partitions. When the settling rate of the fluidization medium in the thermal energy recovery chamber 59 is low, a resting angle is formed for the fluid-5 storage medium at the top of the thermal energy recovery chamber, with excess fluid medium falling from the top of the sloping septum to the primary fluidized bed combustion.

The flu-10 data medium fed to the heat energy recovery chamber 59 forms a gradually descending moving bed due to the gas sprayed from the diffuser 62 and is returned to the primary fluidized bed combustion chamber from the orifice portion 63 after heat transfer together with the heat conducting lines.

The mass flow of diffusion air supplied from the diffuser device 62 to the thermal energy recovery chamber 59 is selected to be in the range of 0-3 Gmf or preferably 0-2 Gmf.

The reason for the above is that, as shown in Fig. 8, the thermal conductivity coefficient varies from a minimum to a maximum of 20 g below 2 Gmf, and the abrasion rate can be controlled, as shown in Fig. 9, with a small range.

In addition, the heat recovery chamber is subjected to reducing atmospheres outside the highly corrosive zone 25 of the primary fluidized bed combustion chamber, and thus the heat conducting wires 65 are subject to less corrosion than the conventional wires. in accordance with the minor. The air flow rate at a fluid flow mass flow of 0-2 Gmf is quite low, for example 0-0.4 m / s (surface velocity) at 800 ° C, depending in practice on the temperature and grain size of the fluidization medium.

Il au i 111> I I! »I I

94170 27

When non-combustible materials larger than the grain size of the fluidizing medium are mixed with the combustible materials, the combustion waste is removed together with a portion of the fluidizing medium by means of a screw conveyor 70 placed on the bottom of the incinerator.

With respect to heat conduction, in addition to the heat conduction due to direct contact between the fluidizing medium and the heat conducting lines 65, there is another form of heat conduction in the heat energy recovery chamber 59 using an upwardly moving gas acting as a heat conducting medium with ascending fluid oscillation. In the latter case, there is no significant boundary layer between the non-thermally conductive solids, unlike conventional thermal conductivity contact between the gas and the solids, with the fluidizing medium becoming well mixed, whereby thermal conduction within the fluidization granules may be limited. These 20 facts should not be disregarded while the medium remains in place, whereby quite good thermal conductivity properties can be achieved. Thus, in the thermal energy recovery chamber of the present invention, it is possible to achieve a high thermal conductivity coefficient of almost. 25 times the thermal conductivity • achieved in a conventional flue gas cooker.

As described above, the heat conduction phenomenon between the fluidizing medium and the thermally conductive surfaces is highly dependent on the strength or weakness of the fluidization, so that the amount of recycled fluidizing medium can be controlled by adjusting the amount of gas fed from the diffuser 62. By also placing the thermal energy recovery chamber 59 so that its movable layer is independent of the primary combustion chamber 35 inside the incinerator, it is possible to manufacture a compact thermal energy recovery device having a high efficiency and a fluidized bed that can be easily monitored.

In a digester using slow-burning combustible materials, such as coal or petroleum coke, it is impossible in most cases to rapidly change the amount of evaporation other than by changing it only in a manner corresponding to the burning rate. In a bubbling digester, the situation becomes even worse compared to the above-mentioned digester, because the thermal energy is then recovered on the basis of the temperature of the fluidized bed.

In the context of the present invention, the amount of heat conduction is abruptly changed between several time periods and fractions by changing the amount of diffusion air in the heat energy recovery chamber. Thus, the change in the amount of thermal energy supplied to the fluidized bed based on the change in the amount of combustible materials fed depends on the burning rate and causes a time delay; however, the amount of thermal energy recovery in the thermal energy recovery chamber of the invention can be rapidly varied by varying the amount of diffusion air in this thermal energy recovery chamber and the reaction difference between heat input and recovery can be attenuated as a temporary change in fluidity Thus, thermal energy can be used without wasting it, and control of the amount of steam with good reaction properties can be achieved, which has not been possible, for example, with a conventional coal burner.

The location of the non-combustible material outlets 69, shown, for example, in the drawing, is preferably determined at locations close to the orifices 63 and at opposite sides of the air diffuser plate in the kiln 51, however, this location is not limited to the above solution.

ia ib> mi »i i m i 94170 29

Figure 4 shows a brushed air diffuser plate 52 in shape; however, if the amount of fluidized air sprayed from the air chambers 54 and 56 is set greater than 4 Gmf, the circulating flow is generated by the sloping partitions in the primary fluidized bed combustor 5, and thus the air diffuser plate 52 can be made as a horizontal plate when burning combustible materials such as slightly non-combustible stones. In this case, the outlet for non-combustible substances can also be omitted.

As described above, the ability of the fluidized bed digester of the present invention to recover thermal energy is quite superior. The following describes a method for monitoring the operation of the cooker of the present invention.

In the context of the present invention, the amount of thermal energy recovered from the thermal energy recovery chamber is controlled according to the requirements of the customer using this recovered thermal energy by adjusting the amount of gas injected from the diffuser device into the thermal energy recovery chamber. Also, the temperature in the primary fluidized bed combustion chamber is controlled by controlling the fuel supply based on the temperature or vapor pressure in said primary fluidized bed combustion chamber, and in addition whereby the kettle can be adjusted immediately according to the user's requirements and can be used under 30 fixed conditions.

Referring to Fig. 4, if, for example, the temperature of the steam from the thermally conductive lines 65 is insufficient, the diffusion air control valve 93 is controlled in its opening direction by the valve 92 the amount of thermal energy increases and the steam temperature rises to the value required by the user.

The temperature of the primary fluidized bed combustion chamber is controlled within certain limits by adjusting the amount of fuel supplied to it and / or the amount of air supplied to the air chambers 54, 55 and 56 based on the temperature of the fluidized bed detected by the heat detector 94.

There is also another method in which the amount of fuel fed to the primary fluidized bed chamber is controlled by a pressure signal, for example where the required amount of steam varies due to user variation, as vapor pressure is the fastest variable in response to the required change.

These reaction properties are shown in Figures 10 and 11, where the steam flow rate changes by + 30% gradually between 70 and 100%.

Fig. 10 shows test results obtained by keeping the amount of air obtained from the diffuser in the thermal energy recovery layer constant with a constant variation of the steam flow rate of + 30%, Fig. 11 shows experimental results obtained in the case where the amount of diffusion air is adjusted in response to a steam flow rate of 30%. % to gradual change. Comparing the two cases, it has been found that the fluidized bed temperature and the steam flow rate are limited to predetermined values over a short period of time, with the range also being small in the case (Figure 11), where the diffusion. the amount of air is adjusted according to the present invention on the basis of the change in the steam flow rate, as compared with the results obtained in connection with the conventional method shown in Fig. 10.

il i> ä. 111. i i i = 1 «94170 31

The temperature range of the fluidized bed was approximately ± 12 ° C and the range of vapor pressure was less than about ± 0.3 kg / cm 2 (0.029 MPa) in the case where the adjustment was performed according to the present invention as shown in Fig. 11.

Fig. 12 also shows the reaction characteristics in the case where the steam flow rate is suddenly changed by -60%, whereby the amount of diffusion air in the heat energy recovery chamber is adjusted based on the above-mentioned change 10 according to the present invention. In this case, it has also been found that the temperature of the fluidized bed is almost constant and the range of the vapor pressure is small.

Another embodiment of the present invention will be described below. The embodiment shown in Fig. 13 corresponds to the case where the present invention is applied to the incinerator with a single rotating fluidized bed according to Fig. 1, the reference numerals being the same as the numbers 20 used in Fig. 3 in meaning and function.

Figure 14 shows an embodiment used when a large size cooker is required. In the embodiment according to Fig. 14, two fluidized bed digesters 25 with internal recirculation shown in Fig. 4 are interconnected.

As shown in Figs. 4 and 14, the operation is performed without difficulty by feeding fuels through a supply opening formed in the ceiling. When burning solid fuels, such as coal with a grain size of less than several centimeters, it is desirable to feed the fuel to the combustion section from a relatively low position instead of the roof, but above the fluidized bed surface using suitable equipment such as a spreader. using the blade 35.

32 t 94170

Thus, when the device is used solely for burning solid fuels, such as coal, it is possible to use only a spreader of the type described without a feed opening in the roof. It is also possible to feed combustible materials containing 5 large pieces from the roof and solid fuels through the above-mentioned spreader to burn both types of materials mixed together.

The internally recycled fluidized bed digesters described above can be most conveniently used in connection with medium and large digesters. For use as small cookers, it is preferable to make them more compact, such an embodiment being shown in Fig. 15. In the embodiment of Fig. 15, the thermally conductive wires 65 included in the layer shown in Fig. 4 are arranged in an almost vertical direction extending beyond the heat recovery chamber. until, this group of heat conducting lines 20 also acts as a means for interconnecting the upper water chamber 91 and the groundwater chamber 92.

By placing a plurality of approximately vertical evaporation lines at the top of the primary fluidized bed combustion chamber and in a free plate around the heat recovery chamber, it is possible to use these lines as reinforcing elements for the cooker body etc., the need for use because the fluid flowing in the thermally conductive lines, including the fluid flowing in the retained lines of the layer si-30, is, automatically recycled.

In addition, the fluidized bed digester and the exhaust gas digester can be combined into a single structural unit, whereby the fluidized bed digester with internal recirculation can be made into a small and economically advantageous embodiment.

94170 33

The structure and operation of the present invention will be described in more detail below. The exhaust gas generated after combustion in the primary fluidized bed combustion chamber is led to flow upwards through a free plate in the part above the combustion chamber and fed from it to the group of thermally conductive lines formed on the periphery of the device, from the top of this group. The gas is then directed to flow downwards in a flow moving almost perpendicular to the direction of said heat conducting lines 10, while the heat transfer is performed. In this case, a part of the unburned ash collected by the guide plates 93 by the inertial gravity is caused to fall towards the moving bed in the thermal energy recovery chamber, after which this unburned ash is completely burned due to its long residence time in said moving bed, thus improving combustion efficiency.

The process described above is particularly effective when using coal, which contains non-combustible coal 20 for a long time to be burned. However, in other cases where a fuel other than coal is used and in which the non-combustible ash of such fuel may not be spread over a large area, a non-combustible ash recycling device 25 may not be required.

If the fuel supply port is formed, for example, as a feed port of the type described enabling top-down supply, it is desirable to blow the secondary combustion air towards the primary fluidized-bed combustion chamber. In such an arrangement, an air curtain effect around the secondary air is expected to prevent fine fuel particles, such as small pulverized carbon granules, from spreading to the combustion exhaust gas and to perform an effective agitation and mixing operation in the free 34 94170 k portion of the plate. between the unburned ash contained in the exhaust gas, thus improving combustion efficiency and reducing NOx and CO densities, etc.

Figure 5 shows a päällisleikkauskuvantoa the direction of arrow 16 of Figure 15 A - A of the line, taken in the direction of its showing in particular a circular digester exemplary embodiment. In particular, this cooker does not need to be made in the shape of a circle on the house shown in Fig. 16, however, the setting of the heat-conducting wires is easy when the cooker is round.

The embodiments shown in Figs. 4, 13 and 14, etc. are preferably made rectangular in shape for structural reasons.

The effects and advantages of the present invention can be summarized as follows.

1. Due to the inclination of the partition wall, by controlling the amount of air sprayed from the air diffuser (62) placed at the rear of the partition wall of the heat recovery chamber, it is possible to cause the fluidization medium to settle and circulate in the moving bed state.

It is also possible to solidify the fluidization medium inside the heat recovery chamber by adjusting the amount of air sprayed from the air diffuser (62) of the heat recovery chamber to zero.

2. Due to the fact that the partition wall separating the thermal energy recovery chamber and the primary fluidized bed combustion chamber is inclined and the mass flow of fluidizing air sprayed from the part below this inclined partition wall is large, it is possible to make the primary Lei

ia iu.i un iii ui e 941 70 35 3. Compared to the Gmf value of the air injected from the air diffuser of the thermal energy recovery chamber into the thermal energy recovery chamber to the primary combustion chamber, the high energy value the amount becomes adequately secured. It is also possible to easily control the amount of fluid medium circulating in the heat energy recovery chamber by adjusting the amount of decomposed air coming from the air diffuser of the heat energy recovery chamber.

4. Since the air diffuser of the heat energy recovery chamber is placed at the rear of the inclined partition, the circulation of the fluidizing medium becomes sufficiently ensured and easily monitored.

5. Since the primary fluidized bed incinerator contains a fluidized bed with an internal circulation, the fluidizing medium fed to the primary fluidized bed combustion chamber becomes uniformly decomposed into the primary combustion chamber immediately after the heat energy is recovered therefrom.

6. The fluidizing medium in the heat energy recovery chamber is caused to descend and circulate in the moving bed state with a mass flow of decomposition air 25 of 0-2 Gmf, whereby the degree of abrasion of the thermally conductive surface becomes quite small, as shown in Fig. 9, compared to current is placed directly inside the fluidizing fluid of the bubbling type.

7. Since the settling rate of the thermal medium in the thermal energy recovery chamber is adjusted to 0-2 Gmf with respect to the mass flow of the decomposition air in the thermal energy recovery chamber, the total thermal energy transfer coefficient changes linearly as shown in Fig. 8.

Claims (6)

A fluidized bed boiler comprising: a) a combustion gun (51) comprising a primary fluidized bed, air diffusion means (52) and a sloping wall disposed above the air diffusion means, the diffusion means generating an upward mass flow, which is greater than on the second screen, b) a heat energy recovery chamber (59) comprising heat exchange surface means (65) for flowing fluid, the heat energy recovery chamber (59) further comprising a heat energy recovery member 62 and an additional layer (62) C) said inclined wall is a inclined intermediate wall (58) which separates the primary fluidized bed from the thermal energy recovery layer such that the primary fluidized bed and the thermal energy recovery layer communicate with each other at the upper and lower ends of the And (d) a portion of the medium may be guided to the v sleeve energy recovery chamber (59) above the upper portion of the inclined partition (58), e) the amount of fluidizing gas being measured. From the additional diffusion means (62) to the heat energy recovery chamber (59) f, the medium contained in the recovery chamber is to sink downwardly into a state of a movable bed, f) the inclined intermediate wall slopes 10 - 60 ° to the horizontal. characterized in that g) the inclined partition is formed such that its projected length in the horizontal direction constitutes 1/6 - 1/2 of the horizontal bottom length of the combustion chamber. 2. A fluidized bed boiler according to claim 1, characterized in that the inclined partition wall (58) is inclined 25 to 45 "in relation to the horizontal plane. 40 941 70 3. A fluidized bed boiler according to claim 1, characterized in that the inclined partition wall (58) slopes 35 ° in relation to the horizontal plane. The fluidized bed boiler according to claim 1, 2 or 5, characterized in that the inclined partition (58) is designed such that the length of its projection in the horizontal direction is 1/4 to 1/2 of the horizontal length of the bottom of the combustion chamber. A method of controlling a fluidized bed boiler 10 comprising a reactor: (a) a primary combustion chamber (51) comprising a primary fluidized bed and air diffusion means (52); (b) a heat energy recovery chamber (59) comprising a heat energy recovery layer. and auxiliary diffusion means (62), c) an inclined partition (58) which separates the primary fluidized bed from the thermal energy recovery layer such that the primary fluidized bed and the heat energy recovery layer communicate with each other at the upper and lower ends) heat exchange surface means (65) arranged in the heat energy recovery layer for flowing through the fluid, in which method under the inclined intermediate wall (58) is measured fluidization gas with a higher mass flow than under the area opposite the intermediate wall, whereby a rising bed is formed the inclined partition (58) and a sinking bed are formed in the middle to the inclined partition, the ascending and descending bed forming a circulating bed, the fluidizing gas supplied by the diffusion means (52) to the area at the inclined partition (58), the mass flow being such that a portion of the the circulating bed medium rises upwardly and reaches the heat energy recovery chamber (59); 5, characterized in that the feed rate of the fuel is controlled in the process. 6. A method according to claim 5, characterized in that the mass flow of the gas of the auxiliary diffusion means (62) arranged at the bottom of the heat energy recovery chamber (62) lies in the range 0-3 Gmf, and the mass flow of the fluidizing air injected from the diffusion means. (52) below the inclined intermediate wall (58) is in the range 4-20 Gmf. «*