CA2740506C - Fluidised bed device with quick fluidisation and saturated flow of circulating solids - Google Patents

Abstract

The invention relates to a fast fluidized bed device comprising a reactor (1, 1 '), a solid separation cyclone (2, 2') at the outlet of this reactor, comprising a top wall (2A, 2'A) called ceiling, a return line of solids (4, 4 ') to the reactor at the outlet of solids of said cyclone and exchangers (5) associated with the flue gas circuit at the outlet of said cyclone, a pipe (6, 6') partially connecting high said cyclone audit reactor. According to the invention, said pipe (6, 6 ') opens into said ceiling (2A, 2'A) of the cyclone.

Description

FLUIDIZED FLUIDIZED BED DEVICE WITH RAPID FLUIDIZATION AND
SATURE FLOW OF CIRCULATING SOLIDS
The invention relates to a fluidized circulating fluidized bed device fast and saturated flux of circulating solids.
A circulating fluidized bed device has a loop configuration drastic solids associating a reactor, a cyclone, a return of solids, of the exchangers and a set of operating parameters in terms of gas velocity in empty cask, of circulating granulometry and in flow of solids.
EP 0 147 445 discloses a fluidized bed device circulating at fast fluidization. If with a solid mufti device such as described in this document, the fluidization velocity reaches relatively high, the pressure drop in the solids flow zone when dense bed is relatively weak. The concentration of the flow of circulating solids is therefore relatively weak.
However, it is desirable to have a high concentration and even a saturated flux of circulating solids, for many reasons and applications, whose some are discussed below.
In case of combustion in a circulating fluidized bed, it is desired to maximize the oxygen content in the fuel oxidant, which in turn reduces proportion of flue gas flow and equipment size but requires extracting most of the heat of combustion in the loop circulating solids. It is then necessary to circulate quantities of solids well superior to those obtained by conventional fluidized bed technology flowing The nearby enriched air combustion technology reduces flow rates fumes and possibly boost the power of an existing installation or the combustion temperature for minerals to be calcined but it remains a content nitrogen in the fumes containing carbon dioxide and water that is to process downstream if only carbon dioxide is to be produced for storage final

2 after condensation of the water vapor.
Carbon dioxide absorption technology on solid and regeneration of these before recycling was proposed as early as 1999 using of the fluidized beds, as described in patent document EP 1 448 876. The problem technique is to circulate enough solids to capture the dioxide of carbon and get rid of solid support deactivations as and when measured absorption / desorption cycles. It is then necessary to circulate quantities of solid far superior to those achieved by conventional bed technology fluidized flowing.
The technology of producing carbon dioxide almost pure from carbonaceous substances by circulation of alternately oxidized oxides and recycled between two fluidized bed reactors goes back to the 1950s and was applied to different concepts, such as the one described in document US Pat. No. 5,509,362. In order to use oxygen carriers from of natural ores to save the process, the technical problem is to achieve complete conversion of carbonaceous substances and to circulate sufficient solid oxygen carriers with much higher fluxes than those obtained by conventional circulating fluidized bed technology.
Cement raw pre-calcination technology, using the bed fluidized circulating fluid, is well known since 1982, for example from the EP 0 059 508. The problem is to be able to achieve a great homogeneity of temperature in the solids mud so as to maximize the operating temperature and pre-convert to the maximum the calcined fraction in calcium silicate which provides hydraulic properties. For obtain a Intense internal mixing gas solids without segregation of flow, it takes so circulate amounts of solids much higher than those obtained by the conventional fluidized bed technology.
Bed reactor technology for flue gas treatment fluidized circulating is well known since 1983, as described in document of EP 0 084 469. For dry desulfurization, the problem

3 technique is to circulate enough solids to capture the dioxide of sulfur by sulphate formation and minimize injected calcium, which reduces the quantity of sub-products that can not be upgraded. To minimize calcium flow to the quasi stoichiometry, it would be necessary to circulate quantities of solids well higher those obtained by conventional circulating fluidized bed technology and ensure a adequate residence time for very fine solids suitable for absorption gas.
It is conventional to connect a circulating fluidized bed reactor with the cydone separator associated by a lateral horizontal pipe to the reactor and at cyclone, as for example it is described in the US patent document 5,339,774.
With such a connection arrangement between reactor and cyclone, this is the internal recirculation to the reactor which is favored. Indeed, in the upper part of reactor, particle packets are formed which only partially engage in the horizontal line connecting to the cyclone, the other part relatively significant downward down the reactor where it is fluidized again by the fluidization gas.
Gold for specific applications of such fluidized bed installations fast, such as thermochemical cycle conversions, it's a better recirculation external to the reactor which is sought, that is to say a best Reactor / cyclone / return pipe / reactor and so a passage a maximum of particles from the top of the reactor to the cyclone.
The object of the invention is to provide a rapid fluidized bed device who achieves external circulation rates in solid three to five times superior to those of circulating fluidized bed conventional technology, while lowering the cost of equipment by improved compactness.
In this way, the invention provides a rapid fluidized bed device.
having a reactor, at least one exit solid separation of this reactor, comprising an upper wall called ceiling, a pipe of return of solids to the reactor at the solids outlet of said cyclone and exchangers associated with the flue gas circuit at the outlet of said cyclone, a pipe

4 connecting in the upper part said reactor to said cyclone, characterized in that said conduct opens into said cyclone ceiling.
The invention also relates to a method of implementing such a bed device fluidized fast, characterized in that a fuel and / or a carrier of reaction of particle size less than 100 microns for 90% of its quantity is injected in said reactor.
The invention relates to a method for implementing such a bed device fast fluidized, comprising the step of injecting into said reactor a fuel and / or a support of reaction of particle size less than 100 microns for 90% of its quantity.
The invention relates to a method for implementing such a bed device fast fluidized, characterized by the same axial gas velocity of between 7 and 9 m / s in said reactor and in said cyclone.
The invention relates to a method for implementing such a bed device fast fluidized, comprising the step of applying to said reactor and said cyclone a same speed axial gas between 7 and 9 m / s.
The invention finally relates to a method of implementing such a device for fluidized bed fast, characterized by a concentration of solids at the place where said driving leads in said cyclone ceiling, between 20 and 60 kg / Nm3 at full load.
The invention finally relates to a method of implementing such a device for fluidized bed fast, including the step of obtaining a concentration of solids at the location where said conduct leads into said cyclone ceiling, between 20 and 60 kg / Nm3 at full charge.
The invention is described below in more detail with the aid of FIGS.
representing that preferred embodiments of the invention.
FIG. 1 is a vertical sectional view of a fluidized bed device fast, consistent with the invention.
FIG. 2 is a partial perspective view of a bed device circulating fluidized according to the invention.
FIG. 3 is a partial view in vertical section of a bed device circulating fluidized according to the invention.

4a FIG. 4 is a vertical sectional view of a fluidized bed device circulating according to the invention, according to another embodiment, in particular under pressure.
Figures 5 and 6 are partial sectional views of a reactor according to the invention.
FIG. 7 is a half sectional view of another embodiment of a reactor according to the invention. FIG. 8 is a top view of a set of reactors according to the invention.
=

FIG. 8 is a view from above of a set of compliant reactors to the invention.
Figures 9 and 10 are views in vertical and horizontal section of a variant embodiment.

Fig. 11 is a vertical sectional view of a variant of production.
Figures 12 and 13 each represent an installation according to FIGS. 14A to 14C show a detail in vertical section, with a view to front and in horizontal section, according to a first variant of production.
FIG. 15 represents a detail in vertical section, according to a second variant embodiment.
FIGS. 16A to 16C show a detail in vertical section, with a view to front and in horizontal section, according to a third variant of production.
FIG. 1 represents a fast fluidized bed device, comprising a reactor 1, a pipe 6 connecting with a cyclone 2 for separation of solid at the outlet of this reactor, comprising a top wall 2A called a ceiling, a solid return line 4 to the reactor at the solids outlet of the cyclone 2 and exchangers 5 associated with the flue gas circuit at the outlet of cyclone 2.
reactor walls, pipes and cydone are preferentially with walls tubed, covered with refractory but can be sheet metal with lining refractory thick.
A line 6 connects reactor 1 to cyclone 2 at the top and opens into the ceiling 2A of the cyclone.
As also illustrated in FIG. 2, this line 6 is substantially axial to the reactor 1 in a first section 6A in the upper part of reactor, with upwardly directed flow, aligned with the vertical axis of symmetry of reactor or parallel to it. This first section 6A, where a speed of solid and gas of 25 to 35 can be obtained at the output of this section 6A, is connected to the reactor 1 by a frustoconical portion of acceleration 1A forming the reactor ceiling, inclined from 15 to 600 with respect to a horizontal plane. This

6 ceiling A may be of circular or square section. A deflector transverse 6C is disposed near the entrance of the first section 6A of the pipe 6 connecting the reactor and the cyclone. This 6C deflector allows to accelerate and to concentrate the diluted solids in a concentrated layer. This first deflector 6C is followed by a second 6D directional deflector which allows of concentrate the solids again.
This first section 6A has at its entrance a restriction skirt of section 7, ensuring a section 3 to 7 times smaller than the section transversal reactor 1, where air or reactive fluid can be injected at a speed of 80 at 150 m / s to allow control of the external circulation of solids at desired level by the operating load of the installation and therefore by times of stay of solids in the conversion zones of two reactors interconnected, for example. This skirt 7 is therefore flared, horizontal section lower than its lower end and advantageously comprises injections fluidization at this lower end and expansion joints at near its upper end.
This pipe 6 is inclined in a last section 68 in the upper part cyclone, downwardly directed flow, the inclination being at least 35 by compared to a horizontal plane. This inclination of 35 can be reduced to 20 if this section has auxiliary fluidizations. So, he's got a flow in the dense phase at the bottom of this last section 68 and a gravitational flow in Mass of solids is favored.
According to the embodiment illustrated in FIG. 2, this first section 6A
and this last section 68 is connected by an intermediate section 6E with a background inclined bottom providing a flow angle of at least 20.
The pipe 6 opens into the ceiling 2A of the cydone near the periphery of the latter by a slot 3 in an arc of a circle, of width constant. The outer peripheral edge of this slot 3 is arranged in continuity with the wall cylindrical of cydone 2, so as not to reduce the speed of solids and contributes at an optimum solid gas separation efficiency in the cyclone.

WO 2010/04961

7 PCT / FR2009 / 051964 Cyclone 2 has a side smoke outlet 2B, by its cone lower, or central 2ile, by its ceiling, bringing these fumes to the heat exchangers 5. A flow heat recovery boiler horizontal, posed, can thus be installed, as illustrated in FIG.
In the case of a lateral exit 2B, the cyclone is provided with a skirt cylindrical 2B "internal which is facing the end of the output 2B with a distance between them. The purpose of this skirt 2B "is to prevent a direct passage of solid circulating towards exit 2B.
The solid return line 4 at the outlet of the cydone is frustoconical at less on its lower part, flared from an overall angle of 5 to 100, its section increasing downstream of the cyclone exit to its other end more low.
Its lower end is connected to a device 8 in the shape of a U, to angles rounded internal. In a variant shown in FIG. 3, this device 8 may be U-shaped, at angles formed by faces 8A inclined 450.
This return sheath solids 4 can be vertical or inclined at most 300 with respect to a vertical plane.
This line 4 may include a branch 8B to a reactor adjacent and means for introducing by gravity 8A of fuels and / or fresh reaction solids. It may also include injections of fluid in walls and perforated 4A ventilation canes located in the heart of flow to lubricate the walls and reduce the coefficients of friction.
The U-shaped device 8 ensures a blockage of the direct passage of gas from from the bottom of reactor 1 at higher pressure to the return line of solid 4.
It comprises a feed 8A by gravity in fuels and / or supports solid reaction. Its uphill part is of a height h, of value range between the value of its diameter and three times this diameter value, so of minimize losses.
FIGS. 9 to 11 represent variant embodiments of this device U and the return of solids to the reactor (s).

8 Figures 9 and 10 show an embodiment of returns multiple solids to multiple reactors. The return sheath of solids 4 in cyclone 2 exit opens into a chamber 18 provided on its bottom inferior of fluidization injection and carrying on its upper part four pipes indinées two of which, 19, 20 may be connected to the reactor 1, of which a 21 can be connected to another reactor and one of which 22 can be connected at an exchanger. The arrangement of U previously described here is shaped so three-dimensional around the return duct 4.
Figure 11 shows an arrangement of U 28 attached to the lower part 12 of the reactor 1. It is then a wall portion of the reactor that forms the U.
This arrangement comprises fluidization injections 29 on its lower bottom.
The the lower part of the reactor 1 has in turn an inclined wall provided with primary fluidization injections 30.
According to another embodiment illustrated in FIG. 4, such a device fast fluidized bed can be pressurized, by moderate pressurization of the order of 6 to 10 bars, the cased walls being then completed by a second external metal enclosure resistant to internal pressure. The driving 6 'of The connection of the reactor 1 'and the cyclone 5' then presents only a first axial section 6'A, in the upper part of the reactor, with flow directed towards the high and a last section 613 inclined, in the upper part of the cyclone, with a flow directed downwards, the inclination being at least 20 O with respect to a plane horizontal.
Such a pipe arrangement 6 'therefore has no section intermediate horizontal direction, as seen in Figure 2. It is Note that even in the case of a non-pressurized device, an arrangement according to the figure can be used and is even advantageous because removing a transfer of direction horizontal solids between the reactor and the cydone.
As also shown in FIG. 1, a reactor 1 for a bed fluidized fast according to the invention comprises a chamber 10 substantially cylindrical for pressure applications, of polyhedral section, preferably square or rectangular, a high part 11 of connection to

9 the entry of the solid separation cyclone 2 and a low part 12 of connection to the cyclone solids outlet pipe 4, of shape corresponding frustoconical.
The enclosure 10 may be of substantially constant section, as illustrated, or be flared at an angle of about 5, its lower section being in upper part.
The enclosure 10 comprises re-mixing profiles 13 in the form of ribs, internal annular of constant section, for example trapezoidal, spread over at least part of its height and preferably, as represented, all the way up the speaker. These ribs 13 have dimensions dependent on the dimensions of the reactor and have a thickness between 50 and 400 mm and are spaced from each other a distance from 1 at 4 m.
As illustrated by arrows in FIG. 5, these ribs 13 have as their function to take off the downward axial annular flow layer of solid which forms at the top of the reactor and deflects it towards the core high velocity gaseous flow central loaded with solids more purposes.
Thus it is obtained a homogeneity of the radial temperatures between the center and the annular periphery of the flow and an optimal transfer of mass and heat between the gases and the different types of solids present in the reactor.
Three embodiments of the re-mixing ribs are shown in Figures 14 to 16.
FIGS. 14A to 14C show cased ribs 102 which are created by tubes deported according to a certain periodicity, for example a tube on two, from a wall consisting of common tubes 101 and fins welded These ribs are coated with a refractory lining 103.
FIG. 15 shows ribs on anchors 106 welded to a wall consisting of common tubes 101 and welded fins 100, on which is cast or tamped with a refractory lining 103 which gives the desired geometry.

Figures 16A-16C shows ribs on metal shelves horizontal perforations 104 supported by vertical stiffenings 105 welded periodically to a wall consisting of common tubes 101 and fins welded A refractory lining 103 provides the desired geometry.
The lower part 12 of the reactor, shown in FIG.
input 14 substantially axial, that is to say aligned with the vertical axis of symmetry of reactor, frustoconical solids, multi-frustoconical or conical.
So is minimized the kinetic energy loss of solids flow rates in circulation and therefore avoided an accumulation of solids at the bottom of the reactor that is a

Typical characteristic of the circulating fluidized bed. It is no longer necessary to use as much fluidization energy and the internal erosions of refractories and fluidization nozzles are also minimized. The speeds of fluidization are between 10 and 40 m / s in this lower part.
The reactor 1 may therefore be devoid of nozzle fluidization grid multiple, which is a complex and expensive investment component, subject to clogging and erosion.
The reactor 1 comprises injections 15 of fluidization means on three to five levels in walls of the enclosure 10 and the lower part 12.
This lower part also has at least one gravity inlet 8A of fuel and / or solid reaction supports, located downstream of the U-shaped device 8 which may also comprise an injection 15 'of means of fluidization at its base, and an extraction arrangement 16 of solid.
This gravity inlet can be equipped with a concentric axial injection of gas to form a gas screen and avoid collages to the walls.
Injections in fluidization means 15, 15 'make it possible to control precisely the velocity profile of the gases in the primary zone of acceleration of the solids that forms the lower part 12 of the reactor. This acceleration is essential to achieve an appropriate flow of solids circulating in the mud and perform the desired reactions in the reactor 1. These injections of means of fluidization can also control local gas atmospheres by

11 example of ensuring the release of fuel nitrogen from fuel down of reactor, thanks to the pyrolysis created by the heat input of the hot solids entering and therefore reduce the oxides of nitrogen in combustions in the air or at oxygen.
The reactor 1 may contain at least one integrated bed 14 ', as represented in FIG. 7, which can be installed on one or more faces of the reactor.
Secondary air supplies 15 can be set to promote the solid filling of this bed 14 '.
Such an integrated bed can operate in fluidized bed or moving bed and allows to control the inventory in dredging for a given global inventory and to control the flow of solids in external circulation to another reactor. This bed integrated 14 'may include a conduit 14A to another reactor and may ensure a carbon and sulfur barrier role between two reactors interconnected.
Preferably, a method of implementing such a bed device fluidized fast is to inject into the reactor 1 a fuel and / or a reaction medium, depending on the application, with a particle size of less than 100 microns for 90% of its quantity and to inject a fluidization gas at the bottom of reactor 1, at a speed of the order of 10 to 40 m / s at the bottom of the reactor 1, the speed gas being between 7 and 9 m / s in the reactor 1 and in the cydone 2.
The concentration of solids where said pipe 6, 6 'opens in said ceiling 2A, 2'A of the cyclone, between 20 and 60 kg / Nm3 at full charge.
Indeed, the circulating fluidized bed device according to the invention has the optimum characteristics to ensure fast fluidization and one saturated flux of circulating solids.
With regard to the reactor and cyclone connection line, which dassiquement is horizontal and is connected laterally to the reactor and cyclone, as described in patent document EP 0 147 445, the conduit 6 according to the invention has an absence of horizontal section, connecting the first section 6A and the last section 6B, and therefore involves a minimum of

12 loss of speed and kinetic energy and avoids any accumulation of solids who disrupt the flow, while ensuring peripheral entry into the cydone, optimally directed for separation of solids and fumes.
This link driving arrangement also makes it possible to lower substantially the height of the cyclone 2 with respect to the ceiling of the reactor 1 and therefore to reduce the overall height of the installation and the frames of support and therefore very significantly improve compactness and reduce costs investment.
With regard to the cyclone solids outlet pipe, which classically is of constant section, the frustoconical shape of this pipe according to the invention avoids any agglomerate and any stagnant zone, of type bridging, solids.
With regard to the device at the bottom of this line, which classically is U-shaped at right angles, the rounded shape or Chisel of the device 8 according to the invention avoids loss of speed and therefore energy, at these angles.
With regard to the reactor, which classically has cased walls vertical and lateral return in solids, the presence of ribs mix 13 ensures optimal mass and heat transfer between gases and different types of solids present in the reactor and the substantially axial inlet 14 of the solids minimizes kinetic energy loss from solid flows in circulation.
It is thus possible to obtain a fast loop of circulation of the solid, with total homogeneity of gas and solids temperatures and maximization mass fluxes of circulating solids over the entire loop, the speed axial axis being the same in reactor 1 and cyclone 2, and to reach a high concentration of solids, of the order of 20 to 60 kg / Nm3 at the inlet of the cyclone. A more compact and therefore less expensive installation is also obtained, particularly in the case of a pressurized device.
The reactor 1 and cyclone 2 assembly forms a simple modular structure since reactor and cyclone are characterized only by the same speed CA 02740506 2011-04-1.9

13 axial from 7 to 9 m / s. It is therefore possible to arrange such modules elementary in lines or polygons. We can then build a set of 2, 3, 4, 6, reactors the equivalent of 100 to 800 MWe for a combustion boiler at air at atmospheric pressure. Figure 8 illustrates the case of a set consisting of six elementary modules reactor 1 and cyclone 2.
It is also possible to associate several cyclones with a reactor 1 as illustrated in Figures 12 and 13.
In the two examples shown, two cyclones 21 and 22 are associated 1. According to FIG. 12, the two cydones are shaped according to the invention, with the duct 61 and 62 connecting the reactor and the cydone opening in the ceiling of each cyclone. According to Figure 13, only a cyclone 21 is so realized, the other cyclone 22 being disposed at mid height of the reactor 1 by means of a side exit. There is then withdrawal of solids at mid-height and in part high.
Such a fast fluidized bed device finds many applications and in particular can form:
a combustion system, solid, liquid or gas containing carbon of fossil or non-fossil origin and intended for steam production; this combustion can be carried out in the air, in the air enriched not more than 90% oxygen or recycled smoke enriched by not more than 90%
oxygen;
a combustion system with metal and alkaline oxides in oxygen transport cycle by oxidation and reduction, comprising injections air or enriched air for oxidation of oxides and water vapor / CO2 recycled for the reduction of oxides, solid, liquid or gaseous fuels containing carbon of fossil or non-fossil origin and intended for production of steam;
a system of the same type as the previous ones, but gasification of fuels of any kind;

14 a system of the same type as the previous ones, but pyrolysis of fuels of all kinds;
a system of cracking of oil cuts or bitumens and crude oils;
a system for capturing sulfur oxides, compounds chlorine or carbon dioxide, downstream from existing boilers:
a system of high temperature treatment of tars and higher order hydrocarbons downstream of a gasification unit and / or of cracking and / or pyrolysis;
a system of precakination and clinkerization of raw cement plant.

Claims (15)

15 1) Fast fluidized bed device comprising a reactor (1, 1 '), at least a cyclone of separation of the solids (2, 2 ') at the outlet of this reactor, comprising a wall higher (2A, 2'A) said ceiling, a return line of solids (4, 4 ') to the reactor in solids outlet of said cyclone and the exchangers (5) associated with the circuit of fumes output of said cyclone, a pipe (6, 6 ') connecting in the upper part said audit reactor cyclone, characterized in that said pipe (6, 6 ') opens into said ceiling (2A, 2'A) of the cyclone. 2) Device according to claim 1, characterized in that said pipe (6, 60 is substantially axial to said reactor in a first section (6A, 6'A) in part high reactor, flow directed upwards. 3) Device according to claim 2, characterized in that said first section (6A, 6'A) is connected to said reactor by a frustoconical portion (1A, 1'A) forming the ceiling of said reactor (1, 1 '), inclined from 15 to 60 ° relative to the vertical. 4) Device according to claim 2 or 3, characterized in that cross deflector inlet (60) is disposed at the inlet of said first section (6). 5) Device according to any one of claims 2 to 4, characterized in what said pipe (6, 6 ') is inclined in a last section (6B, 6'B) in part high of cyclone (2, 2 ') with downward flow. 6) Device according to claim 5, characterized in that said tilt is from to minus 20 ° to the horizontal. 7) Device according to any one of claims 1 to 6, characterized in what said pipe (6, 6 ') opens into said ceiling (2A, 2'A) of the nearby cyclone of the periphery of the latter by a slot (3) in an arc. 8) Device according to any one of claims 1 to 7, characterized in what said return pipe of solids (4) is frustoconical at least on its part lower, its increasing section downstream of the exit of the cyclone (2) towards its other more end low. 9) Device according to claim 8, characterized in that said pipe truncated is flared at an overall angle (.alpha.) of 5 to 10 °. 10) Device according to claim 8 or 9, characterized in that said more end bass is connected to a U-shaped device (8) with internal angles rounded. 11) Device according to claim 10, characterized in that said U-shaped device is shaped three-dimensionally around said return line (4), in order to form multiple returns to multiple reactors. 12) Device according to claim 10, characterized in that said U-shaped device (28) is connected to the lower part of said reactor (1), a wall portion of the reactor forming the U. 13) Method for implementing a fast fluidized bed device such as defined in one any of claims 1 to 12, the method comprising the step of injecting in said reactor (1, 1 ') a fuel and / or a reaction medium of granulometry less than 100 microns for 90% of its quantity. 14) Method for implementing a fast fluidized bed device such as defined in one any of claims 1 to 12, the method comprising the step to apply in said reactor (1, 1 ') and in said cyclone (2, 2') a same axial speed gas between 7 and 9 m / s. 15) Method for implementing a fast fluidized bed device according to any one Claims 1 to 12, including the step of obtaining a concentration of solid to where said pipe (6, 6 ') opens into said ceiling (2A, 2'A) of cyclone, between 20 and 60 kg / Nm3 at full load.