CA1316413C

CA1316413C - Internal circulating fluidized bed type boiler and method of controlling the same

Info

Publication number: CA1316413C
Application number: CA000570806A
Authority: CA
Inventors: Shigeru Kosugi; Tsutomu Higo; Takahiro Ohshita; Naoki Inumaru; Hajime Kawaguchi
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 1987-07-17
Filing date: 1988-06-30
Publication date: 1993-04-20
Anticipated expiration: 2010-04-20
Also published as: WO1989000659A1; DK128289A; ATE85682T1; FI94170B; NO168912C; KR950007013B1; AU609731B2; BR8707989A; FI94170C; NO168912B; NO891168L; DK128289D0; EP0369004A4; AU7708887A; RU2059150C1; DE3784174T2; EP0369004A1; NO891168D0; KR890701950A; DK166694B1

Abstract

ABSTRACT OF THE DISCLOSURE
An internal recycling type fluidized bed boiler which comprises: a primary fluidized bed incinerating chamber constructed by an air diffusion plate, and an inclined partition wall provided above the portion of the diffusion plate where the mass flow of the air injected from the diffusion plate is greater than that from the other portion so as to interfere with the upward flow of the fluidizing air injected from that portion and deflect it towards the portion above the diffusion plate where the mass flow of gas injected is smaller; and a thermal energy recovery chamber formed between the inclined partition wall and the side wall of an incinerator; the inclined partition wall being inclined by 10-60° relative to the horizon and arranged such that the length of its projection in the horizontal direction is 1/6-1/2 of the horizontal length of the incinerator bottom, and a method of controlling the above fluidized bed boiler with respect to the amount of thermal energy recovered from the thermal energy recovery chamber by regulating the amount of air injected from the diffuser in the thermal energy recovery chamber based on demands from the user side utilizing the recovered thermal energy, the fuel feeding amount to the primary fluidized bed incinerating chamber being controlled based on the temperature in the primary fluidized bed incinerating chamber.

Description

INTERNAL CIRCULATING FLUIDIZED BED TYPE BOILER AND
MET~OD OF CONTROLLING THE SAME
Technical Field:
1 The present invention relates to a boiler utilizing an apparatus for incineratiny coal, smokeless coal, coal dressing sludge, oil coke, bark, bagasse, industrial waste, municipal waste and other combustibles in a fluidized bed for recovering thermal energy from the fluidized bed, and a method of controlling the amount of diffusion gas to be blown into a thermal energy recovery chamber and the amount of fuel to be supplied in order to regulate the amount of thermal energy recovered and to maintain the constant temperature in the primary incinerating chamber of the fluidized bed.
Brief Explanation of Drawin~s:
Figs. 1 ~nd 2 are sectional views expla~ning the conventional fluidized bed type boiler; Fig. 3 is a schematic illustration e~plaining the principle of the present invention; Fig. 4 is a sectional view of an internal circulating fluidized bed typa boiler explaining in outline the construction according to the present invention; Fig. 5 is a graph showing the relationship between the amount of air for fluidization ~Gmf) at the portion below the inclined partition wall and the amount of the fluidizing medium circulated; Fig. 6 is a graph indicating the relationship between the amount of diffusing air (Gmf) in the thermal energy recovery chamber and the descending rate of the downward moving bed in the thermal energy recovery chamber;
Fig. 7 is a graph indicating the relationship between the mass flow for fluidization (Gmf) and the overall thermal conducting coefficient in the conventional bubbling type boiler; Fig. 8 is a graph indicating the relationship between the diffusion mass ilow ~Gmf) in the thermal energy recover~ chamber and the overall thermal conducting coeffi--2- 1 31641') 1 cient in the internal circulating fluidized bed type boiler according to the present invention; Fig. 9 is a graph ~how-ing the relationship between the mass flow for fluidization and the abrasion rate of the thermal conducting conduit;
Figs. 10 and 11 show variations in the fuel feeding amount, vapor pressure and the fluidized bed temperature relative to the lapse of time without and with regulation of the fluidizing mass flow for the thermal energy recovery chamber in response to stepwise change of the vapor flow rate; Fig.
12 shows similar variations relative to the lapse of time in response to lumpwise change of the vapor flow rate; Figs. 13 and 14 are sectional drawings explaining other embodiments of the internal recycling type fluidized bed boiler accord-ing to the present invention; Fig. 15 is a sectional side view of an internal recycling type fluidized bed boiler explaining still another embodiment of the present invention which is particularly adapted or use as a small boiler;
Fig. 16 is a section taken in a plan view on a line shown by the arrows A - A in the drawing of the embodiment shown in Fig. 15 which particularly illustrates the section in plan view of an internal recycling type fluidized bed boiler - adapted for use in a circularly pac~aged boiler; and Figs. 17 - 19 illustrate fluidizing patterns in a primary fluidized bed incinerating chamber with the relationship between the horizontal length L of the incinerator bottom and the projection length Q of the inclined partition wall in the horizontal directlon.
Prior Art:
With respect to a conventional f luidizing bed type boiler, there are three kinds as noted below which can be distinguished from each other by giving consideration to the arrangement of the thermal conducting portion and the incineration of minute unburnt combustibles that are scattered from the fluidlzed bed.
(1) a fluidized bed boiler of non-recycling type (referred to as a conventional fluidized bed boiler or bubbling type bo~ler), and -2a-1 (2) a fluidized bed boiler of recycling type.
In the non-recycling type shown in Fig. 1, thermal conducting conduits are arranged within the fluidized bed and the heat transfer is effected under high heat transfer efficiency by virtue of physical contact between the conduits and the burniny substances or fuels at the high temperature and the fluidizing medium. However, unburnt substances are discharged outside without being burnt. In the recycling types such as shown in Fig. 2, a part of the ~inute combustibles which are not yet burnt, as well as ash or fluidi~ing medium (a recycling solid), merges into a flow of combustion gas and is directed to a heat transferring portion (external heat exchanger) provided independently of the combustor where incineration of the unburnt substances is continued, the solid after this heat transfer being returned to the combustor together with a part of the combustion gas . This type of boiler being given on account of the kind of recycling noted above.

(3) intern~l recycling type fluidized bed boiler As to an lnternal recycling type fluidlzed bed boiler, a fluldized bed lncinerator provided with a deflectlng strUCtUre pro~ecting from a wall of the furnace for alding the circulat~on of fluidi~ing medlum and a non-fluidlzlng thermal e~ergy recovering chamber between ~urnace walls is disclosed in the specificatlon oi U.K.
Patent No. 1604314. However, the transferring movement o~ the fluidlzing medium ~rom the thermal ener~y recovery chamber to the fluidiæed bed lncinerating chamber ln the fluidlzed bed incinerator disclosed ln thls speeificatlon ls e~ected by a feed screw at the bottom o~ the thermal energy recovery chamber independently or by mi~lng wlth fuel supplled from a fuel supply chamber disposed in the lower portion o~ the thermal energ~ recovery chamber.
~`
/

_ 3 _ 1 31 641 3 In the fluidized bed type boiler, a variety of fuels having different characteristics may be incinerated according to the particular incineration process but s~veral drawbacks have recently been noticed. In regard to the bubbling type, its loading capacity, the complexity of the fuel feeding system, the requirement for a large quantity of lime for denitration, and the abrasion of thermal conducting conduits, etc. have been recognized as drawbacks inherent thereto. It has been realized that the recycling type is capable of solving these inherent drawbacks. However, further technical developments remain to be achieved with respect to maintaining proper temperatures in the circulating system, scaling-up of the apparatus and solving the problem of restarting a boiler once it has been stopped.

Summary of the Invention The inventors of this application have been investigating the above problems in order to seek appropriate solutions thereto and have found the following matters to be effective. That is, in a circulating fluidized bed type incinerator, an inclined partition wall is provided on the inside of the incinerator wall and above the end portion of the diffusion plate to form a primary incinerating chamber of the fluidized bed and provision for a thermal energy recovery chamber is also made between the back side of the inclined partition wall and the incinerator wall or between the rear sides of the two partition walls so that the recovery chamber communicates at the upper and lower portions thereof with the primary incinerating chamber of the fluidized bed, thermal conducting conduits adapted to pass heating medium therethrough being inserted into the thermal energy recovery chamber and a diffuser for the thermal energy recovery chamber being provided at the lower part of the recovery ~ ., -4- t 3 1 6 4 1 , chamber and al~ng the back side of the partition wall. The heated fluidizing medium introduced into the thermal energy recovery chamber beyond the upper portion of the inclined partition wall is subjected to the fluidizing gas blown from the diffuser and regulated in an amount of 3 - 3 Gmf or preferably 0 - 2 Gmf to form a static bed or a descending moving bed of the fluidizing medium so that the thermal energy of the fluidizing medium is recovered ky the heating medium passing through the thermal conducting conduits. The inventors found that, by the arrangement noted above, it is possible to easily control the temperature of the primary incinerating chamber of the fluidized bed in the incinerator above explained while effectively recovering the thermal energy by the thermal conducting conduits in the fluidized zone where the degree of abrasion of the thermal conducting conduits is small.
The inventors have further investigated and developed an internal recycling type fluidized bed boiler provided with the thermal energy recovery chamber that accompanies the inclined partition wall and the method for recovering thermal energy and controlling the feeding rate of the fuel and found it possible to form an effective circulating fluidized bed using the fluidizing medium heated in the primary chamber and to introduce a sufficient amount of the heated fluidizing medium re~uired in the thermal energy recovery chamber by arranging the inclination of the inclined partition wall to be 10 - 60 or preferably 25 -45 relative to the horizon and the projection length of the inclined partition wall in the hori~ontal direction on the bottom of the incinerator to be 1/6 - 1~2 or preferably 1/4 - 1/2 of the horizontal length of the ~ottom of the incin-erator. Also the inventors found it possible not only to fully meet the demand from users utilizing the recovered thermal energy but also to limit the degree of temperature variation in the primary chamber within a small range by controlling the amount of thermal energy recovered ~rom the thermal energy recovery chamber by regulation of the thermal calories of the- heating medium passed through the thermal ~0 , conducting conduits, for example by regulating the flow rate, pressure and temperature of the vapor or the temperature, etc. of the hot water, at the same time as regulating the amount of air blown from the diffuser in the thermal energy recovery chamber in response to variations in the demands from the users, for Pxample those regarding the vapor pressure and temperature and the regulation of the amount of fuel supplied, such being determined in response to the demands from the users or based upon the temperature in the primary chamber.
lo The internal recycling type in this specification and appended claims, refers to an arrangement in which a space is provided within a combustor or incinerator so as to be separated from a primary incinerating chamber and a thermal conducting portion is dispersed within the space so that the recycling is effected within the incinerator.
That is, the present invent~on is directed to an internal recycling type fluidized bed boiler comprising: a primary fluidized bed incinerating chamber constructed by an air diffusion plate provided at the bottom of an incinerator and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at one side than that at another side; and an inclined partition wall provided above a side of said diffusion plate where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said another side of said diffusion plate where the mass flow is smaller; a thermal energy recovery chamber formed between said inclined partition wall and a side wall of the incinerator or between the two inclined partition walls; a heat exchanging surface means provided within said thermal energy recovery chamber for the passage of a heat sink fluid therethrough; and an air diffuser provided at a lower portion of said thermal energy recovery chamber and at a back side of said - 6 - l 31 ~4 1, inclined partition wall; said thermal energy recovery chamber being communicated at upper and lower portions thereof with said primary fluidized bed incinerating chamber, said inclined partition wall being inclined by 10-60 relative to the horizontal and the projection length thereof in the horizontal direction being 1/6-1/2 of the horizontal length of the incinerator bottom, a moving bed being formed above the portion of said diffusion plate where the injected mass flow is smaller so that a fluidizing medium descends and diffuses within the moving bed, and a circulating fluidized bed being formed above the portion of said diffusion plate where the mass flow of the fluidiæing air is greater so that said fluidizing medium is actively fluidized and whirled towards a position above said moving bed and a part of said fluidizing medium being introduced into said thermal energy recovery chamber beyond an upper portion of said inclined partition wall, the formation of said moving bed and said whirling fluidized bed being effected by regulation of the amount of air injected upwardly from said diffusion plate and regulation of the amount of fluidizing air injected from said diffuser in said thermal energy recovery chamber causing the fluidizing medium within said recovery chamber to descend in the state of a moving bed for circulation.
The invention is also directed to a method of controlling an internal recycling type, fluidized bed boiler constructed by comprising: a primary fluidized bed incinerating chamber constructed by an air diffusion plate provided at the bottom of an incinerator and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at one side than that at another side; and an inclined partition wall provided above a portion of said diffusion plate where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said another side of said diffusion plate where the mass flow is smaller; thermal energy recovery chambers formed between - 7 - 1 31641~
said inclined partition wall and a side wall of the incinerator and between the back sides of two inclined partition walls; a heat exchanging surface means provided within said thermal energy recovery chamber for the passage of a heat sink fluid therethrough; and an air diffuser provided at a lower portion of said thermal energy recovery chamber and a back side of said inclined partition wall; said thermal energy recovery chamber being communicated at a upper and lower portions thereof with said primary fluidized bed incinerating chamber; said method comprising regulating the amount of air injected from said diffusion plate so that a moving bed is formed above the portion of said diffusion plate where the injected mass flow is smaller with a fluidizing medium descending and diffusing within said moving bed, and circulating fluidized bed is formed above the lS portion of the diffusion plate where the mass flow of the fluidizing air is greater with said fluidizing medium being actively fluidized and circulated towards a position above said moving bed and a part of said fluidizing medium being introduced into said thermal energy recovery chamber beyond an upper portion of said inclined partition wall, the fluidizing air being injected from said diffuser in said recovery chamber so as to cause said fluidizing medium within said recovery chamber to descend and recycle in the state of a moving bed, controlling the amount of thermal energy recovered by said thermal energy recovery chamber by the regulation of the amount of gas injected from said diffusor in said recovery chamber based on demands from a user side utilizing generated vapor and hot water, and controlling the amount of fuel supplied to the primary fluidized bed incinerating chamber based on the temperature of said primary fluidized bed incinerating chamber.

Detailed Description ~f the Preferred Embodiments 1 Hereinafter, the present invention will be explained in detail referring to the accompanying drawings.
In Fig. 3, a diffusion plate 52 is provided at the bottom of an incinerator 51 for introducing fluidizing air fed by a blower 57 through a fluidizing air feeding conduit 53, the diffusion plate 52 being configured in the shape of a hill (chevron shape) approximately symmetrical about the center line of the incinerator so that the opposite end portions are lower than the center portion thereof. The fluidizing air fed from the blower 57 is arranged to be injected upwardly from the air diffusion plate 52 through air chambers 5~, 55 and 56 and the mass flow of the fluidiz-ing air in;ected from the opposite end air chambers 54 and 56 is arranged to be sufficient to form the fluidized bed of the fluidizing medium within the incinerator 51, while the mass flow of the fluidlzing air injected from the center air chamber 55 is selected to be smaller than that from the former.
Inclined partition walls 58 are provided above the opposite end air chambers 54 and 56 as a deflecting wall means designed to interfere with the upwardly directed passage of fluidizing air and to deflect the air towards the center of the incinerator, the whirling flows in the directions of the arrows shown being generated due to the presence of the inclined partition walls 5~ and the difference in the mass flow of the inJ'ected fluidizing air.
On the other hand, thermal energy recovery chambers 59 are formed between the back side surfaces of the inclined parti-tion walls 5g and side walls of the inclnerator so that a part of the fluidizing medium may be introduced during the ~,"' operation into the thermal energy recovery chambers 59 beyond the upper ends of the inclined partition walls 58.
In the present invention, the inclined portion of each inclined partition wall 58 is arranged to incline by 10-60, or preferably 25-45, relative to the horizontal and the projection length thereof in the horizontal direction relative to the incinerator bottom is arranged to be 1/6-l/2, or preferably 1/4-l/2, of the horizontal length L of the respective half of the incinerator bottom.
The angle of the inclination relative to the horizontal and the projection length in the horizontal direction of the inclined partition wall are both factors which influence the fluidizing state of the fluidizing medium and the amount of grains introduced into the thermal energy recovery chambers.
Incidentally, the meaning of "L" and "~" and the flowing modes of the fluidizing medium are shown in Fig. 17.
If the angle of inclination of the inclined portion is either smaller than 10 or greater than 60 relative to the horizontal, a satisfactory whirling flow is not produced and the condition under which the fuel is incinerated deteriorates. This angle is preferably in the range between 25 and 45 and it is particularly preferable if it is set at approximately 35.
In the case where the projection length ~ of the inclined partition wall in the horizontal direction relative to the incinerator bottom is greater than 1/2 of the incinerator bottom length L as shown in Fig. 18, the amount of fluidizing medium deflected from the inclined partition walls and caused to fall on the center of the incinerator becomes smaller thereby adversely affectiny the formation of the moving bed at the incinerator center as well as the descending and diffusing mode of the ~uel charged into the incinerator center.

1 3 1 6~ 1 `
~ n the other hand, .in a case such as that shown in Fig.
19 where the projection length ~ of the inclined partition wall relative to the incinerator bottom is smaller than 1/6 of the incinerator bottom length L, the formation of the whirling flow and particularly the forming mode of the . . . 1 0 -lo- 1 3~ 6~ 1 ~
moving bed at the incinerator center is caused to deterio-rate whereby the fuel entraining effect is also affected adversely and the deflected flow of fluidizing medium into the recovery chamber becomes insufficient.
~t the lower portion of the thermal energy recovery chamber 59 and the back side of the inclined partition wall 58, a diffuser 62 for the thermal energy recovery chamber is provided for introducing gas such as air from a blower 60 through a feeding conduit 61. At the portion in the thermal energy recovery chamber 59 adjacent to the place where the diffuser 62 is disposed, an opening port 63 is provided and the fluidizing medium introduced into the thermal energy recovery chamber 59 is caused to continuously or intermit-tently descend, depending on the operating mode, and recycled into the incinerating portion through the opening port 63.
Fig. 4 shows an embodiment based on the principle of Fig. 3.
The descending amount of the fluidizing medium in the thermal energy recovery chamber for recycling is regulated by the amount of diffusing air for the thermal energy recovery chamber and the amount of fluidizing air for the incinerating portion. That is the amount of fluidizing medium (Gl) introduced into the thermal energy recovery chamber is increased as shown in Fig. 5 if the amount of fluidizing air injected from the diffusion plate 52, partic-ularly that from the end air chambers 54 and 56 which is intended to cause fluidization at the incinerating portion, is increased. Further, as shown in Fig. 6, the amount of fluidizing medium descending in the thermal energy recovery chamber is changed approximately proportional to the change in the amount of diffusing air blown into the thermal energy recovery chamber when in the range 0 - l Gmf and it becomes approximately constant if the amount of diffusing air for the thermal energy recovery chamber is increased beyond 1 Gmf. This constant amount of fluidizing medium is almost equivalent to the amount of fluidizing medium (Gl) intro-duced into the thermal energy recovery chamber and thus the 1 6 4 1 ) amount of fluidizing medium descending in the thermal energy recovery chamber becomes equivalent to a value corresponding to G,. By controlling the air amount both for the inciner-ating portion and the recovery chamber, the descending amount of fluidizing medium in the thermal energy recovery chamber 59 may be regulated.
The descent of the fluidizing medium in the static bed when in the range of O - 1 Gmf is due to the difference in weight of the fluidizing medium (the difference in height of the fluidized bsds) as between the thermal energy recovery chamber and the primary fluidized bed incinerating chamber and, in the case where the mass flow is over 1 Gmf, the height of the moving bed portion becomes slightly higher or approximately equal to the other. The recycling of the fluidizing medium is assisted by a deflecting flow with a sufficient amount of fluidizing medium brought about by the inclined partition wall.
Now, the relationship between the height of the fluidized bed and the recycling amount of the fluidizing medium (the deflecting flow) will be explained in detail.
In the case where the surface of the fluidized bed is lower than the upper end of the inclined partition wall, the air flow moving upwardly along the inclined partition wall is given its direction by that wall and injected along the inclined partition wall from the fluidized bed, the fluidiz-ing medium being accompanied therewith. The injected air flow is put in a state different from that in the fluidized bed and freed from the fluidizing medium with which the fluidized bed is filled, and the sectional area of the air flowing passage is suddenly enlarged whereby the injected air flow is diffused and its speed is reduced to a few meters per second, becoming a gentle flow~ and is exhausted upwardly. Therefore, the fluidizing medium that accompanies the injected air flow loses its kinematic energy to fall due to gravity and the friction with the exhaust gas as the grain size of the fluidizing medium is too large (approxi-mately 1 mm) to be carried with the air flow.

-12-- 131641~, In the case where the surface of the fluidized bed is higher than the upper end of the inclined partition wall, a part of the fluidizing medium accompanied with air masses gathered by the partition walls is injected along the deflecting partition wall with the direction imparted in a manner similar to that in the circulating fluidized bed type incinerator, while the other part, due to a sudden boiling phenomenon derived from the explosion of bubbles, is boiled upwardly like fire works just above the upper end of the inclined partition wall and falls all around the periphery.
Accordingly, a part of the fluidizing medium is introduced in a large amount towards the ~ack side of the partition wall, i.e. the thermal energy recovery chamber.
That is, the moving direction of the injected fluidizing medium becomes closer to upright as the surface becomes higher above the upper end of the inclined partition wall. Therefore, the amount of fluidizing medium introduced into the thermal energy recovery chamber becomes large in the case where the surface is slightly above the upper end of the inclined partition wall.
In Fig. 5 is shown the relationship between the amount of fluidizing air in the portion below the inclined partition wall in the primary fluidized bed incinerating chamber and the amount of fluidizing medium recycled through the thermal energy recovery chamber.
For example, during the operation under the state Ll, if the height of the fluidized bed is lowered due to the scattering of the abraded fluidizing medium, the recycling amount of the fluidizing medium is suddenly reduced to, for example, below l/lO of that of the former and thermal energy recovery cannot be performed. Thus, what is important is the amount of the fluidizing air and, if it is arranged to be more than 4 Gmf and preferably more than 6 Gmf, the value of Gl/Go is maintained over l and the required and suffi-cient amount of the recycling fluidizing medium may beobtained even if the height of the fluidized bed is chang~d.
Further, by arranging the mass flow of the air injected from the diffuser in the bottom of the thermal 1 ~ 1 6~ ~ `

energy recovery chamber to be O - 3 Gmf, or preferably 0 -~ Gmf, and the mass flow of the fluidizlng air in~ected from the diffu~ion plate disposed below the inclined partition wall to be 4 - 20 Gmf or preferably 6 - 12 Gmf, that is by always keeping the mass flow to be larger at the incinerat-ing chamber side than at the thermal energy recovery chamber, the amount of fluidizing medium fed back to the primary fluidized bed incinerating chamber from the thermal energy recovery chamber may be adequately assured.
As to the moving bed in the thermal energy recovery chamber, it is referred to in the academic sense as a static bed in the case where the mass flow is O - 1 Gmf and a fluidized bed in the case where the mass flow is over 1 Gmf and it is commonly known that a minimum mass flow of 2 Gmf is required for generating a stable fluidized bed. On the other hand, in the case of the moving bed according to the present invention which is always descending and moving, the descending moving bed is satisfactorily formed until the mass flow is increased to th0 order of 1.5 - 2 Gmf without causing the destruction of the moving bed by the bubbling phenomenon. It is assumed that the grains of the fluidizing medium gradually descend and move under a vibrating mode whereby the fluidiziny air is converted into small air bubbles uniformly flowing upward towards the upper portion 2S of the fluidized bed.
Inside the thermal energy recovery chamber 59, thermal conducting conduits 65, through which a heat sink fluid such as vapor or water, etc. is passed, are arranged so that the thermal energy is recovered from the fluidizing medium by effecting a heat transfer with the fluidizing medium downwardl~ moving in the thermal energy recovery chamber. The thermal conducting coefficient in the thermal energy recovering portion is greatly varied as shown in Fig. 8 in a case where th~ amount of the diffusing air in the thermal energy recovery chamber is changed in the range of O - 2 Gmf.

131641 ~

Now the characteristics such as the load response characteristics brouyht about by the formation of the moving bed in the thermal energy recovery chamber will be explained The general relationship between the overall thermal conducting coefficient and the mass flow for fluidization is shown in Fig. 7. Between the values of the mass flow in the range of 0 - l Gmf, the increase in the thermal conducting coefficient is small and it suddenly increases when the mass flow becomes over l Gmf. AS a method for turning down the fluidized bed boiler utilizing the above phenomenon, the "Wing Panel Type" was introduced in DOE Report, 6021 (2), 655 - 633 (1985) and the thermal conducting coefficient in response to the variation of the fluidizing mass flow is stated to be insensitive (static bed) or too sensitive (fluidized bed).
Incidentally, upon reviewing certain foreign patent specifications, several cases are found which seem to be similar to the present technology in the point that the incinerating chamber and the thermal energy recovery chamber are separated; however, all the partitions disclosed therein are constructed with a vertical orientation and the fluidiz-ing medium in the thermal energy recovery chamber is in the mode for being changed to the static bed and to the fluidiz-ing bed, it being the static bed when the thermal energy recovery is small in amount and the fluidizing bed in which the medium is blown upwardly from the lower portion when the thermal energy recovery is large iIl amount. This is because it is difficult to produce a deflected flow with a verti-cally oriented partition as compared to the case where the partition is inclined. It is therefore inevitable in the case of the vertically oriented partition that the fluidiz-ing medium is arranged in both the incinerating chamber and the thermal energy recovery chamber to be in a fluidized state (similar to water) so that the fluidizing medium is caused to flow between the two chambers.
~ he relationship between the overall thermal conduct-ing coefficient and the mass flow for fluidization is shown in Fig. 8. As shown in Fig. 8, it changes almost linearly and, thus, the amount of thermal energy recovered and the 1 31 64 ~ j temperature of the primary fluidized bed incinerating chamber may be controlled optionally. Further, such control may be easily effected simply by regulation of the amount of diffusing air in the thermal energy recovery chamber.
Also it is said that the abrasion rate of the thermal conducting conduits in the fluidized bed is proportionate to the cube power of the mass flow for fluidization and such relationship is shown in Fig. 9. Accordingly, the problem of abrasion regarding the thermal conducting conduits may be solved by arranging the amount of diffusing air blown into the moving bed in the thermal energy recovery chamber to be O - 3 Gmf or preferably O - 2 Gmf.
In order to regulate the amount of thermal energy recovered, regulation of the amount of recycling fluidizing medium is effected, as explained before, while effecting simultaneous regulation of the thermal conducting coeffi-cient. That is, if the amount of fluidizing gas in the air chambers 54 and 56 for the primary fluidized bed incinerat-ing chamber is made constant and the amount of diffusing air in the thermal energy recovery chamber is increased, the amount of recycling fluidizing medium is increased and the thermal conducting coefficient is simultaneously increased to greatly increase the amount of thermal energy recovered as the effect of a combination of the two factors. From the viewpoint of the temperature of the fluidizing medium in the fluidized bed, the above corresponds to the effect of preventing the temperature of the fluidizing medium from being raised above the predetermined temperature.
As a means for introducing the diffusing gas into the thermal energy recovery chamber 59, several means may be considered but it is generally disposed such as to be inclined at the back side of the inclined partition wall (the side facing the thermal energy recovery chamber) so as to effectively utilize the thermal energy recovery chamber.
Also, in the diffuser, the open ports for injecting the diffusing air are made smaller as their location becomes closer to the tip end of the diffuser taS the height of the 131G~1 ) bed becomes smaller) so that the diffusing air is prevented rom being injected in large amounts at the tip end portion.
The respective sizes of the open ports are preferably determined so .hat an approximately uniform diffusing amount is injected over the full length of the diffuser 62 with the diffusing air amount being 2 Gmf. That is, when the above is met, it is possible to obtain the maximum amount of thermal energy recovered by all the thermal conducting surfaces in the thermal energy recovery chamber and the abrasion rate of the thermal conducting surfaces may be kept small over all the surfaces.
In Fig. 4, numeral 66 is a combustible charge inlet provided at the upper portion of the incinerator 51 and 67 is a steam drum for forming a circulating passage (not shown) with the thermal conducting conduits 65 in the thermal energy recovery chambers 59. Numeral 69 represents incombustible discharge outlets coupled to the opposite end sides of the air diffusion plate 52 in the bottom of the incinerator 51 and 70 is a screw conveyor provided with screws 71 each having a helex opposite to the other.
Incidentally, the location of the combustible charge inlet is not limited to the upper portion of the incinerator and it may be disposed at the side of the incinerator as a spreader 56' for charging coal, etc. therethrough.
The combustibles F charged through the combustible charge inlet 66 or 66' are whirled and incinerated in the fluidizing medium which is circulating under the influence of the whirling flow caused by the fluidizing air. At this time, tha fluidizing medium at the upper center above the air chamber 55 is not accompanied by a violent up-and-down motion thereof and forms a descending moving bed which is in a weak fluidizing state. The width of this moving bed is narrow at the upper portion thereof and the trailing ends thereof are extended in the opposite directions to reach the portions above the air chambers 54 and 56 at the opposite side ends, thus being subjected to the fluidizing air injected at a greater mass flow from both air chambers and blown upwardly. Accordingly, a portion of each trailing end 1 3 1 64 1 , ~ 17-is displaced and, t~us, the bed just above the air chamber 55 descends under gravity. Above this bed, the fluidizing medium piles up having been supplemented from the fluidizing bed, as explained later, and the fluidi~ing medium above the air chamber 55 forms a gradually and continuously descending moving bed with the repetition of the above modes.
The fluidizing medium moved above the air chambers 54 and 56 is blown upwardly and deflected and whirled by the inclined partition walls 58 towards the center of the incinerator 51 and falls on the top of the central moving bed and is circulated again as explained before, a part of the fluidizing medium being introduced into the thermal energy recovery chambers 59 beyond the upper portions of the inclined partition walls. In the case where the descending rate of the fluidizing medium in the thermal energy recovery chamber 59 is slow, the angle of repose for the fluidizing medium is formed at the upper portion of the thermal energy recovery chamber and the excess fluidizing medium falls from the upper portion of the inclined partition wall to the primary fluidized bed incinerating chamber.
The fluidizing medium introduced into the thermal ener~y recovery chamber 59 forms a gradually descending moving bed due to the gas injected from the diffuser 62 and it is returned to the primary fluidized bed incinerating chamber from the opening portion 63 after the thermal transfer is effected with the thermal conducting conduits.
The mass flow of the diffusing air introduced from the diffuser 62 in the thermal energy recovery chamber 59 is selected from values in the ran~e of O - 3 Gmf or preferably - 2 Gmf The reason for the above is that, as shown in Fig. 8, the thermal conducting coefficient varies from the minimum to the maximum below the value of 2 Gmf and the abrasion rate can be controlled, as shown in Fig. 9, within a small range~
Further, the thermal energy recovery chamber is out of the strong corrosive zone of the primary fluidized bed incinerating chamber under the reducing atmospheres and, -18- l 31 641 ~
thus, th~ thermal conductlng conduits ~5 are subjected to less corrosion as compared to the conventlonal ones and the degree of abrasion of the thermal conducting conduits 65 is made quite small because the fluidi~ing rate in this portion is, as explained before, low. As to the speed of air flow in the fluidizing air mass flow range O - 2 Gmf, it is q~ite low, such as O - 0.4 m/sec. ~superficial velocity), for example while it practically depends on the temperature and grain size of the fluidizing medium.
In a case where the co~bustibles are mixed with incombustibles having a size greater than the grain size of the fluidizing medium, the incineration residue is dis-charged together with a part of the fluidizing medium bv the screw conveyor 70 disposed at the bottom of the incinerator.
Regarding the thermal conduction in the thermal energy recovery chamber 59, in addition to the thermal conduction that takes place due to the direct contact between the fluidizing medium and the thermal conducting conduits 65, there is another form of thermal conduction that utilizes the rising gas moving upwardly as the conduct-ing media, the gas moving up with irregular vibrat~on as the fluidizing medium moves. In the latter case, there is substantially no boundary layer between the solid articles prohibiting the thermal conduction, in contrast to the ordinary contact thermal conduction between gas and solid articles, and the fluidizing medium is well agitated so that the thermal conduction within the grains of the fluidizing medium may be neglegible, which fact may not be disregarded in a case where the medium is stationary; thus, quita substantial thermal conducting characteristics may be obtained. Accordingly, in the thermal energy recovery chamber according to the present invention, it is possible to obtain a large thermal conducting coefficient almost e~ual to ten times that obtained in the conventional incinerating gas boiler.
~ s explained above, the thermal conducting phenomenon that occurs between the fluidizing medium and the thermal conducting surfaces largely depends on the strength or , ~
~ .. .

1 3 1 64 1 7) weakness of the fluidi~ation and the amount of recycling fltlidizing medium can be controlled by regulating the amount of gas introduced from the diffuser 62. Also, by arranging the thermal energy recovery chamber 59 with its moving bed to be independent from the primary incinerating chamber within the incinerator, it is possible to construct a compact thermal energy recovery apparatus in which the turning down ratio is large and the fluidized bed may be easily controlled.
In a boiler using combustibles having a low inciner-ating rate su~h as coal or oil cokes as fuels therefor, it is impossible in most cases to rapidly vary the vaporizing amount except for varying the vaporizing amount alone in correspondence with the incinerating rate. In a bubbling type boiler, the situation becomes still inferior compared to that in the former boi~er because the thermal energy recovery is effected based on the temperature of th0 fluidized bed.
However, in the present invention the thermal conducting amount is instantaneously varied in the range between several times and several fractions by changing the amount of diffusing air in the thermal energy recovery chamber. Therefore, the variation in the thermal energy input into the fluidized bed due to the variation in the feeding amount of the combustibles depends on the incinera-tion rate and causes a time lag; however, the amount of thermal energy recovery taking place in the thermal energy recovery chamber according to the present invention can be rapidly varied by varying the amount of diffusing air in the thermal energy recovery chamber and the response difference between the thermal input and the thermal recovery can be absorbed as a temporary change in the temperature of the fluidizing medium due to the heat sinking capacity of the fluidizing medium forming the fluidized bed. Accordingly, the thermal energy can be utilized without waste thereof and the regulation of the vaporizing amount having good response characteristic, which cannot be achieved with a conventional boiler such as one incinerating coal, can be obtained.

131641~, Incidentally, the locations o~ the incombustibles discharge openings 69 areJ as shown for example in the drawing, preferably determined at positions near the opening ports 63 and the opposite side ends of the air diffusion plate in the incinerator 51; however, the location is not limited to that explained above.
In Fig. 4, the air diffusion plate 52 is illustrated as having the shape of a hill; however, if the amount of the fluidizing air injected from the air chambers 54 and 56 is arranged to be more than 4 Gmf, the whirling flow is formed in the primary fluidized bed incinerating chamber due to the effect of the inclined partition walls and, therefore, the air diffusion plate 52 may be made a horizontal one in the case where combustibles such as coal containing a few incombustibles are incinerated. Also, the incombustible discharge opening may be omitted.
As explained above, the capability of the fluidized bed boiler according to the present invention to recover thermal energy is quite superior. Now, the method of controlling the boiler according to the present invention will be explained below.
In the present invention, the amount of thermal energy recovered from the thermal energy recovery chamber is controlled, in response to the demands of the user utilizing the recovered thermal energy, by regulating the amount of gas injected from the diffuser into the thermal energy recovery chamber. Also, the regulation of the temperature in the primary fluidized bed incinerating chamber is effected by controlling the fuel charging amount based on said temperature or the vapor pressure and, in the boiler according to the present invention, the thermal conducting coefficient can be optionally adjusted and the variation of the amount of thermal energy recovered in the present invention is aksorbed as variation in the sensible heat of the fluidizing medium whereby the boiler can be controlled instantaneously to meet the demands of the user and can be operated under stable conditions.

- 2l -The explanation is made in relation to Fig. 4. For example, in a case where the temperature of the vapor withdrawn from the thermal conducting conduits 65 is insufficient, a diffusing air regulating valve 93 is regulated in its opening direction by a regulator 92 for the valve 93 based on the temperature sensed by a thermo-sensor 91 on a vapor withdrawing conduit 90 so as to increase the amount of diffusing air injected so that the amount of thermal energy recovered is increased and the vapor temperature is raised to that demanded by the user.
The temperature of the primary fluidized bed incinerating chamber is controlled within a certain range by regulating the amount of fuel fed to the primary fluidized bed incinerating chamber and/or by regulating the amount of air fed to the air chambers 54, 55 and 56 based on the fluidized bed temperature sensed by a thermo-sensor 94.
There is another method wherein the amount of fuel fed to the primary fluidizing bed incinerating chamber is controlled by a pressure signal, for example in the case where the amount of vapor demanded is varied due to a load variation on the user's side, since vapor pressure is the factor which most rapidly changes in response to a change in the demand.
The response characteristics are shown in Figs. 10 and 11 wherein the vapor flow rate is changed by +30% stepwise from 70% to 100%.
Fig. 10 shows test results obtained when the amount of air from the diffuser in the thermal energy recovery chamber was maintained constant while the vapor flow rate was varied by +30 stepwisely, and Fig. 11 shows test results obtained in a case where the amount of diffusing air was regulated in response to the +30% stepwise variation in the vapor flow rate. Upon .~

- 21A 1 31 6'-~ I 3 comparing the two, it is found that the fluidized bed temperature and the vapor flow rate are constrained to predetermined values within a short time and the variation range is also made small in the case (Fig. 11) where the diffusing air amount is regulated -22- 1 31 64 1 7~
accordin~ to th~ present invention in response to the varia-tion in the vapor flow rate, as compared with the results for the conventional method shown in Fig. 10.
Incidentally, the variation range of the fluidized bed temperature was approximately ~12C and that of the vapor pressure was approximately below +0.3 kg/cm2 (0.029 MPa) in the case where the regulation was effected according to the present invention as shown in Fig. 11.
The responding characteristics are also shown in Fig. 12 when the vapor flow rate is varied lumpwisely by -60~ wherein the diffusing air amount of in the thermal energy recovery chamber is regulated in response to the above variation in accordance with the present invention. In this case also, it ls found that the fluidized bed temperature is almost constant and the variation range of the vapor pressure is small.
Next, another embodiment according to the present invention will ba explained referring to Fig. 13. The embodiment shown-in Fig. 13 corresponds to the case wherein the present invention is applied to the incinerator in which a single whirling fluidized bed is present, the reference numerals being the same as those used in Fig. 3 with respect to the meaning and function thereof.
Fig. 14 shows an embodiment to be used when a large size boiler is required. The embodiment shown in Fig. 14 is constructed by combining the two internal recycling type fluidized bed boilers shown in Fig. 4.
As shown in Figs. 4 and 14, the operation is effected without difficulty by charging fuels from the charge inlet provided in the ceiling~ In the case where solid fuels such as coal having a grain size below several centimeters are incinerated, it is preferable to charge the fuel into the incinerating portion from a relatively low position instead of from the ceiling and yet still higher than the surface of the fluidized bed by using a suitabla type of equipment such as a spreader adapted to scatter the fuel by means of a rotary blade.

,,~^~4 -23- 1 3 ~ 6 4 1 ') Accordingly, in a case where the apparatus is used solely for incinerating solid fuels such as coal, it is possible to provide the inlet at a position other than the ceiling and simply to provide a spreader of the above type.
Also it is possible to charge combustibles containing large size objects from the ceiling and to charge solid fuels from the spreader just explained so as to incinerate them both mixed together.
The internal recycling type fluidized bed boilers herein above explained are the sort that are preferably applied to boilers that are medium or large in size. As for small pac~age boilers, it is desirable for them to be made more compact and, thus, an embodiment designed to such end is illustrated in Fig. 15. In the embodiment shown in Fig. 15, the thermal conducting conduits 65 shown within the bed in Fig. 4 are oriented in an almost vertical direction and are extended to an exhaust gas heat conducting portion provided above the thermal energy recovery chamber so that this group of thermal conducting conduits is arranged to also serve as means for unitarily coupling a top water chamber 91 and a bottom water chamber 92.
By arranging the approximately vertical evaporating conduits in a plural number in a free board at the upper portion of the primary fluidized bed incinerating chamber and around the thermal energy recovery chamber, it is possible to utilize them as members for reinforcing the boiler body as well as to eliminate the need for auxiliary devices such as a forcible circulating pump and associated conduits, etc. because the fluid in the thermal conducting conduits including that in the conduits within the bed is automatically circulated.
Further, a fluidized bed boiler and an exhaust gas boiler can be combined as a unitarily structure so that an internal recycling type fluidized bed boiler can be made economically available in a small size.
The construction and function of the present inven-tion are further described hereinbelow in detail. The exhaust gas generated after the incineration in the primary _~4_ 1 31 6~1 3 fluidized bed incinerating chamber is passed upwardly through the free board at the portion above the incinerating chamber and thence introduced into the group of thermal conducting conduits formed around the periphery from the upper portion of the group. It is then moved downwardly in a flow moving in a direction that is nearly normal relative to the thermal conducting conduits while effecting heat transfer. At this occasion, a part of the unburnt ash collected by means of baffle plates 93 due to the inertia-gravity is caused to fall towards the moving bed in thethermal energy recovery chamber so that the unburnt ash is then completely incinerated due to its long dwelling time in that moving bed, thereby improving the incinerating efficiency.
The above situation is particularly effective when coal is used, the unburnt carbon of which needs a long time to be incinerated. However, in other cases where a fuel other than coal is employed and the unburnt ash thereof may not scatter widely, means for recycling the unburnt ash may not be needed, As to the fuel charge inlet, if it is arranged, for example as a type allowing charging from the top as illustrated, it is preferable to blow the secondary incin-erating air towards the primary fluidized bed incinerating chamber. By the arrangement above, an air curtain effect brought about the secondary air is expected to prevent fine fuel particles such as minute powdered coal from being scattered together with the incineration exhaust gas as well as to perform an effective agitation and mixing operation in the free board portion so that it may also contribute to effect sufficient contact between oxygen in the secondary air and the unburnt ash in the exhaust gas, thereby improv-ing the incinerating efficiency and lowering the density of NOx and C~, etc.
3~ Fig. 16 is a planar sectional view taken along the line shown by the arrow A - A in Fig. 15 and it particularly illustrates an example of a circular type boiler. In a case ` -2S- 1 316~
where it is a small size package boiler, it is not parti-cularly necessary to make it a circular type as shown ln Fig. 16, but manufacturing the arrangement of the thermal conducting conduits is made easy if it is made circular.
Incidentally, in the ~mbodiments shown in Figs. 4, 13 and 14, etc., it ls preferable to arrange them in a rectangular configuration from the construction viewpoint.
The effect and advantages of the present invention may be summarized as noted below.
~ Because of the inclination of the partition wall, it is possible, by controlling the amount of air inJected from the air diffuser (62) disposed at the rear of the partition wall of the thermal energy recovery chamber to cause descending and circulation of the fluidizing medium in the state o~ a moYing bed within the thermal energy recovery chamber as well as to control the amount o~
fluidlzing medium circulatlng so as to optionally regulate the amount of thermal energy recovered.
Also, lt is possible to put the fluldlzing ~edium withln the thermal energy recovery chamber ln the sta-tionary state by regulating the amount of air in~ec~ed from the alr diffuser (62) of the thermal energy recovery chamber so that It is zero.
~ Because of the fact that a boundary wall separat-lng the thermal energy recovery chamber and the primary fluldized bed lncinerating chamber ls an lnclined partition wall and the mass flow of the fluidixing air ln~ected from the portlon below the inclined partition wall is large, ~t is posslble to make the amount of fluidizing medium introduced from the primary fluidizing bed incinerating chamber into the thermal energy recovery chamber large.
~ Relatlve to the Gmf of the alr ln~ected from the alr diffuser of the thermal energy recovery chamber lnto the thermal energy recovery chamber, the Gmf of the alr injected to the primar~ incinerating chamber at the ~`

portlon ad~acent the lower openlng of the thermal energy recovery chamber is large, so the circulating amount o-f the fluidiæing medium into the thermal energy recovery chamber is adequately assured. Also, it is possible to easily control the amount of fluldizing medium circulat-ing in the thermal energy recovery chamber by regulating the amount of air diffusing from the air diffuser of the thermal energy recovery chamber.
~ Because the air diffuser of the thermal energy recovery chamber is provided at the rear of the inclined partition wall, the circulation of the fluidizing medium is adequately assured and is easily controlled.
~ Because the primary fluidising bed incinerating chamber constituted an lnternal recycling type fluidized bed, the fluidizlng medium which is introduced from the thermal energy recovery chamber to the primary fluidized bed incinerating chamber after recovery of the thermal energy therein is smoothly dlffused in the primary incineratlng chamber, thereby being heated instantaneously.
~ The fluidizing medium within the thermal energy recovery chamber is caused to descend and circulate in the state of a moving bed with difPusing air in the mass flow range of O - 2 Gmf and, therefore, the abrasion rate of the thermal conductlng surface is made quite small, as is apparent from Fi~. 9, compared to a case wherein the thermal conducting surface under whlch the heat sink fluid is flown is dlrectly disposed within the fluidized medium of a bubbling type boiler.
~ Since the descending rate of the thermal med~um within the thermal energy recovery chamber is regulated in the range of O - 2 Gmf with respect to the mass flow of the difPusing air in the thermal energy recovery chamber, ~he overall thermal energy transmitting coeffi-cient is linearly changed as shown in Flg. 8, so the regulation o~ thermal energy recovery is made easy.

-. ~

Claims

1. An internal recycling type fluidized bed boiler comprising:
a primary fluidized bed incinerating chamber constructed by an air diffusion plate provided at the bottom of an incinerator and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at one side than that at another side;
an inclined partition wall provided above a side of said diffusion plate where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said another side of said diffusion plate where the mass flow is smaller;
a thermal energy recovery chamber formed between said inclined partition wall and a side wall of the incinerator or between the back sides of two inclined partition walls;
a heat exchanging surface means provided within said thermal energy recovery chamber for the passage of a heat sink fluid therethrough; and an air diffuser provided at a lower portion of said thermal energy recovery chamber and a back side of said inclined partition wall;

said thermal energy recovery chamber being communicated at upper and lower portions thereof with said primary fluidized bed incinerating chamber, said inclined partition wall being inclined by 10°-60° relative to the horizontal and the projection length thereof in the horizontal direction being 1/6-1/2 of the horizontal length of the incinerator bottom, a moving bed being formed above the portion of said diffusion plate where the injected mass flow is smaller so that a fluidizing medium descends and diffuses within the moving bed, and a circulating fluidized bed being formed above the portion of said diffusion plate where the mass flow of the fluidizing air is greater so that said fluidizing medium is actively fluidized and whirled towards a position above said moving bed and a part of said fluidizing medium being introduced into said thermal energy recovery chamber beyond an upper portion of said inclined partition wall, the formation of said moving bed and said whirling fluidized bed being effected by regulation of the amount of air injected upwardly from said diffusion plate and regulation of the amount of fluidizing air injected from said diffuser in said thermal energy recovery chamber causing the fluidizing medium within said recovery chamber to descend in a state of a moving bed for circulation.

2. An internal recycling type fluidized bed boiler as claimed in claim 1, wherein the mass flow of the air injected from said diffuser at the bottom of said thermal energy recovery chamber is in the range of 0-3 Gmf, and the mass flow of the fluidizing air injected from said diffusion plate below said inclined partition wall is in the range of 4-20 Gmf.

3. An internal recycling type fluidized bed boiler as claimed in claim 1, or 2 wherein said inclined partition wall is inclined by 25°-45° relative to the horizontal.

4. An internal recycling type fluidized bed boiler as claimed in claim 1, or 2 wherein said inclined partition wall is inclined by 35° relative to the horizontal.

5. An internal recycling type fluidized bed boiler as claimed in claim 1, or 2 wherein said inclined partition wall is formed such that said length of its projection in the horizontal direction is 1/4-1/2 of the horizontal length of said bottom of said incinerator.

6. A method of controlling an internal recycling type fluidized bed boiler constructed by comprising:
a primary fluidized bed incinerating chamber constructed by an air diffusion plate provided at the bottom of an incinerator and adapted to inject fluidizing air upwardly under a mass flow that is at least greater at one side than that at another side;
an inclined partition wall provided above a portion of said diffusion plate where the mass flow is greater so as to interfere with the upward flow of the fluidizing air and thereby to deflect the air towards a portion above said another side of said diffusion plate where the mass flow is smaller;
a thermal energy recovery chamber formed between said inclined partition wall and a side wall of the incinerator or between the back sides of two inclined partition walls;
a heat exchanging surface means provided within said thermal energy recovery chamber for the passage of a heat sink fluid therethrough; and an air diffuser provided at a lower portion of said thermal energy recovery chamber and a back side of said inclined partition wall;
said thermal energy recovery chamber being communicated at upper and lower portions thereof with said primary fluidized bed incinerating chamber;
said method comprising regulating the amount of air injected from said diffusion plate so that a moving bed is formed above the portion of said diffusion plate where the injected mass flow is smaller with a fluidizing medium descending and diffusing within said moving bed, and a circulating fluidized bed is formed above the portion of the diffusion plate where the mass flow of the fluidizing air is greater with said fluidizing medium being actively fluidized and circulated towards a position above said moving bed and a part of said fluidizing medium being introduced into said thermal energy recovery chamber beyond an upper portion of said inclined partition wall, the fluidizing air being injected from said diffuser in said recovery chamber so as to cause said fluidizing medium within said recovery chamber to descend and recycle in the state of a moving bed, controlling the amount of thermal energy recovered by said thermal energy recovery chamber by the regulation of the amount of gas injected from said diffuser in said recovery chamber based on demands from a user side utilizing generated vapor and hot water, and controlling the amount of fuel supplied to the primary fluidized bed incinerating chamber based on the temperature of said primary fluidized bed incinerating chamber.

7. A method of controlling the internal recycling type fluidized bed boilers as claimed in claim 6, wherein the mass flow of the air injected from said diffuser at a bottom of said thermal energy recovery chamber is in the range of 0-3 Gmf, and the mass flow of the fluidizing air injected from said diffusion plate below said inclined partition wall is in the range of 4-20 Gmf.

8. An internal recycling type fluidized bed boiler as claimed in claim 2, wherein the mass flow of the air injected from said diffuser at said bottom of said thermal energy recovery chamber is in the range of 0-2 Gmf, and the mass flow of the fluidizing air injected from said diffusion plate below said inclined partition wall is in the range of 6-12 Gmf.

9. A method controlling the internal recycling type fluidized bed boilers as claimed in claim 7, wherein the mass flow of the air injected from said diffuser at said bottom of said thermal energy recovery chamber is in the range of 0-2 Gmf, and the mass flow of the fluidizing air injected from said diffusion plate below said inclined partition wall is in the range of 6-12 Gmf.

10. A method of controlling a fluidized bed boiler, including an incinerator containing a primary fluidized bed of fluidizing medium and a diffusor means, a thermal energy recovery chamber containing a thermal recovery bed of fluidizing medium and an auxiliary diffusor means, an inclined partition wall separating said primary fluidized bed and said thermal recovery bed with said primary fluidized bed and said thermal recovery bed being in communication with each other at upper and lower ends thereof, a heat exchanging surface means provided within said thermal recovery bed for the passage of a fluid therethrough, said method comprising:
supplying a fluidizing gas from said diffusor means at a higher mass flow rate to a region below said inclined partition wall than to a region opposite said partition wall, and thereby forming a rising bed at said inclined partition wall and a descending bed opposite said inclined partition wall, with said rising and descending beds forming a circulating bed;
controlling the mass flow of said fluidizing gas from said diffusor means to said region of said inclined partition wall such that part of the fluidizing medium in said circulating bed flies upwardly and reaches said energy recovery chamber; and regulating the mass flow of a gas supplied by said auxiliary diffusor means to said thermal recovery bed, thereby controlling the overall coefficient of heat transfer and thus controlling the amount of thermal energy recovered by said fluid passing through said heat exchanging surface means.

11. The method of claim 10, comprising providing said diffusor means at the bottom of said incinerator.

12. The method of claim 10, comprising providing said thermal energy recovery chamber between said inclined partition wall and a side wall of said incinerator or between back sides of two inclined partition walls.

13. The method of claim 10, comprising providing said auxiliary diffusor being at a lower portion of said thermal energy recovery chamber and a back side of said inclined partition wall.

14. The method of claim 10, comprising providing said partition wall to be inclined by 10°-60° relative to the horizontal.

15. The method of claim 14, comprising providing said inclined partition wall to be inclined by 25°-45° relative to the horizontal.

16. The method of claim 10, comprising providing the projection length of said inclined partition wall in the horizontal direction to be 1/6-1/2 of the horizontal length of the bottom of said incinerator.

17. The method of claim 16, comprising providing said projection length to be 1/4-1/2 of said horizontal length of said bottom of said incinerator.

18. The method as claimed in claim 10, comprising injecting said gas from said auxiliary diffusor means at the bottom of said thermal energy recovery chamber at a mass flow in the range of 0-3 Gmf, and injecting said fluidizing gas from said diffusor means below said inclined partition wall at a mass flow in the range of 4-20 Gmf.

19. The method as claimed in claim 16, wherein said mass flow of gas injected from said auxiliary diffusor means is in the range of 0-2 Gmf, and the mass flow of gas injected from said diffusor means below said inclined partition wall is 6-12 Gmf.

20. The method of claim 10, further comprising controlling the rate of flow of fuel to said incinerator.

21. The method of claim 20, comprising regulating the temperature in said primary fluidized bed by controlling the amount of said fuel charged thereto as a function of said temperature in said primary fluidized bed or of the vapor pressure.

22. The method of claim 20, comprising controlling the temperature of said primary fluidized bed within a predetermined range by regulating the amount of said fuel charged thereto and/or by regulating the amount of said gas supplied to said diffusor means.

23. The method of claim 22, comprising sensing the temperature of said primary fluidized bed by a thermo-sensor and conducting said regulating as a function of said sensed temperature.

24. The method of claims 20, comprising controlling the amount of said fuel fed to said primary fluidizing bed as a function of a pressure signal.

25. A fluidized bed boiler comprising:
an incinerator including a primary fluidized bed and a diffusor means for supplying thereto different amounts of a fluidizing gas;
a thermal energy recovery chamber including a thermal recovery bed and an auxiliary diffusor means for supplying thereto a gas;
an inclined partition wall separating said primary fluidized bed and said thermal recovery bed such that said primary fluidized bed and said thermal recovery bed are in communication with each other at upper and lower ends thereof;
heat exchanging surface means, provided within said thermal recovery bed, for the passage of a fluid therethrough;
said auxiliary diffusor means being located at a lower portion of said thermal energy recovery chamber, and said thermal recovery chamber having adjacent said lower portion thereof an opening to enable material of said thermal recovery bed to move downwardly through said opening from said thermal energy recovery chamber to said incinerator; and a portion of said diffusor means being beneath said inclined partition wall and providing an upward mass flow of said fluidizing gas in the area of said inclined partition wall that is larger than the mass flow provided by other parts of said diffusor means.

26. The boiler of claim 25, wherein said diffusor means is positioned at a bottom of said incinerator.

27. The boiler of claim 25, wherein said thermal energy recovery chamber is formed between said inclined partition wall and a side wall of said incinerator or between back sides of two inclined partition walls.

28. The boiler of claim 25, wherein said auxiliary diffusor is positioned at a lower portion of said thermal energy recovery chamber and adjacent a back side of said inclined partition wall.

29. The boiler of claim 25, wherein said partition wall is inclined by 10°-60° relative to the horizontal.

30. The boiler of claim 29, wherein said inclined partition wall is inclined by 25°-45° relative to the horizontal.

31. The boiler of claim 25, wherein said inclined partition wall is formed such that the length of its protection in the horizontal direction is 1/6-1/2 of the horizontal length of the bottom of said incinerator.

32. The boiler of claim 31, wherein said inclined partition wall is formed such that said length of its projection in the horizontal direction is 1/4-1/2 of the horizontal length of said bottom of said incinerator.

33. The boiler of claim 25, wherein the mass flow of the gas injected from said auxiliary diffusor means at a bottom of said thermal energy recovery chamber is in the range of 0-3 Gmf, and the mass flow of the fluidizing gas injected from said diffusor means to beneath said inclined partition wall is in the range of 4-20 Gmf.

34. The boiler of claim 33, wherein the mass flow of the gas injected from said auxiliary diffusor means at said bottom of said thermal energy recovery chamber is in the range of 0-2 Gmf, and the mass flow of the fluidizing gas injected from said diffusor means to below said inclined partition wall is in the range of 6-12 Gmf.