WO2007009334A1

WO2007009334A1 - FLUlDIZED BED REACTOR

Info

Publication number: WO2007009334A1
Application number: PCT/CN2006/001197
Authority: WO
Inventors: Sebastian Zimmer
Original assignee: Sebastian Zimmer
Priority date: 2005-06-03
Filing date: 2006-06-02
Publication date: 2007-01-25
Also published as: NZ564804A; CA2610826C; BRPI0611328A2; CN100528323C; RU2008100026A; RU2403966C2; AU2006272299B2; CN101189061A; NZ588976A; AU2006272299A1; CA2610826A1; CN1712121A; AU2011200770A1

Abstract

A fluidized bed reactor (1), which can also be called constant flow velocity reactor, contains a fluidizing chamber comprising a conical casing (3) which houses an insert (2) of conical shape. By this design, an annular space (4) is created between the casing (3) and the insert (2), which functions as fluidizing chamber and produces a gas flow velocity, which either remains constant or decreases or increases, depending on the geometry of the two components. The reactor can be used for stabilizing the gas flow passing through the fluidizing chamber of the reactor, optimizing gas/solid distribution, improving agglomerate discharge to optimize the processes in the reactor.

Description

FLUlDIZED BED REACTOR

FIELD OF THE INVENTION

The invention relates to a fluidized bed reactor with a fluidizing chamber and a gas inlet and a gas outlet. If required, the gas inlet as well as the gas outlet can be designed into several ducts.

BACKGROUND INFORMATION

During the operation of such a reactor, a so-called fluidized bed is formed in the fluidizing chamber. This is to be understood as a gas/solid matter mixture, which is in turbulent condition. Due to the turbulences in the fluidized bed, the solid matters, the gases and the water fed to the fluidized bed are mixed perfectly, whereby an optimal mass transfer or adsorption is made possible. Classical fluidized bed, circulating fluidized bed or so-called reflux circulating fluidized bed reactors are used for various chemical processes. In most cases, a gas passes through the reactor from bottom to top. After the gas inlet, the reactor has a constriction area that consists either of a fluidization plate (perforated plate), a single nozzle or a multiple nozzle (following described as nozzle bottom). In the area of the constriction the gas velocity should be high enough to prevent the solids above it from falling through. Above the constriction, there is the fluidizing chamber, which is either cylindrical, conical or has a conical section part followed by a cylindrical section part. Above the fluidizing chamber, most reactors have a gas outlet duct in the lateral wall of the reactor points the lateral side, which points to the side. Other designs provide for a centrally arranged gas outlet pipe which points to the top. The essential disadvantage of the known fluidized bed reactor designs is that gas of varying flux (caused for example by upstream systems)frequently lead to fluctuations in the fluidized bed, which

- l - reduce the efficiency of the process and/or cause continually disturbances of the operation, e.g. the operation of the upstream system. Countermeasures are gas recirculation (gas return) or the addition of auxiliary air to the inlet gas flow, so that the minimal gas flow rate passing through the reactor does not fall below 60% of the full load rate in the majority of cases. Since the systems connected to the reactor often require a fluctuation of the flow rate between 30% and 100%, considerable expenses of increased energy consumption and additional apparatuses are caused in order to stabilize the process in the reactor, (increasing the gas flow rate velocity to bigger than 60%).

CONTENT OF THE INVENTION

The first goal of the invention is to create a fluidized bed reactor, whose fluidized bed can be operated with nearly constant parameters (in particular constant gas velocity) and which can be optimally adjusted even with varying inlet gas flow rates (e.g. 30% - 100%).

To realize the above first goal, the fluidizing chamber (4) of the reactor (1) comprises a conical or parabolic casing (3), which houses an insert (2), which also has a conical or parabolic shape. By this design, an annular space 2, which functions as a fluidizing chamber is created between the casing (3) and the insert (2), and which produces a gas flow velocity, which either remains constant, decreases or increases, depending on the geometry of the two components. Therefore, such a reactor can also be called constant flow velocity reactor.

By lowering or lifting the insert (2) (in the direction of the double arrow(5)), the gas velocity can be increased or decreased in the fluidizing chamber. So when the gas flow velocity fed to the reactor changes, a nearly constant gas flow velocity can be achieved in the annular space by lowering or lifting the insert.

The reactor can be designed in a way that the cross sections of the fluidizing chamber(4) having a annular space can be diminished or extended(see figure 1 or

2).

The invention makes the previously known expensive countermeasures superfluous.

Moreover, the invention creates stable operating conditions over broad load ranges as they are normally only possible with constant gas flow rates. The impact on up- or downstream systems is minimized by the use of a constant annular space reactor.

An annular space fluidized bed reactor, by its geometry casing and inserts according to the invention, makes it possible to optimize the operation of fluidized bed processes - in particular when the gas flow rates passed through the fluidized bed reactor vary - whereby strong negative impacts on systems up- or downstream of the reactor are avoided.

Another known problem of fluidized bed reactor is that, inside "circulating fluidized beds" as well as inside static fluidized beds which are not operated with constant gas flow rates, agglomerates may sink or fall within the fluidizing chamber, mostly along the wall. When the agglomerates reach the constricted area, they are torn apart by the high velocity gas, which may lead to considerable pressure peaks, particularly within load ranges of the maximum gas flow rate < 70% - 80% such pressure peaks may result in considerable disturbances of plant operation, which in turn impede proper operating of the plant.

The solution to this problem is the second goal of the invention. To solve this problem, the inventor provides for an agglomerate separator(see Fig. 4), which is designed as an annular space opening (6) or as a large number of staggered openings arranged across the circumference of the fluidizing chamber of a fluidized bed reactor or as an outlet situated in the center of the reactor. The openings can be situated either in the conical enlargement below the cylindrical part of the fluidizing chamber, immediately at the junction between the conical enlargement and the cylindrical section; in the cylindrical section of a conventional fluidized bed reactor; at any point of the nozzle bottom or at any point of the outer wall or of the inner cone of an annular space fluid bed.

Described is an agglomerate separator which optimizes fluidized bed reactors in such a way that the agglomerates can be discharged from the fluidizing chamber through openings located at the circumference or a discharge outlet located on the nozzle bottom. In particular for fluidized bed processes which are operated with varying loads, the invention results in more stable operating conditions and in a considerable reduction of impacts on connected systems. It is the function of the agglomerate separator to lead out the recirculating agglomerates and conglomerates from the fluidizing chamber (4). Then the solid matters can be fed to the fluidized bed again by means of controlled or uncontrolled feeders (8). Figure 4 shows such an agglomerate separator with an annular space opening (6). Here, the solid matters are fed to a floating trough (7), from which they can be re-fed to the fluidized bed reactor in a controlled way, e.g. via several lines evenly distributed across the circumference.

By the agglomerate separator, the expenditure which have previously been necessary are reduced. Moreover, the agglomerate separator creates more stable operating conditions over broad load ranges as they are normally only possible within a smaller load range (gas flow rates). The impact on systems arranged up- or downstream of the reactor is minimized by the use of an agglomerate separator. Another also known problem of fluidized bed reactor is, flue gas outlet. In the case of the conventional reactor head design, the solid-laden gas is discharged centrally to the top, or to the side in one direction. Since the gas normally has a higher core flow in this area than in other areas of the reactor, so-called roller flows occur, which result in a solid reflux along the reactor walls. If the principle of a central outlet towards the top is applied, the roller flow is even, but there may be a concentration of solids, which will then sink as agglomerates down the wall. With a lateral outlet on one side, such a concentration is partially avoided and there is not such a pronounced roller formation, but the gas flow is still inhomogeneous and there are more pronounced local agglomerate formations. Above impact to be avoided is the third goal of the invention. The invention provides that the product-laden gas can be discharged in radial direction and then downwards, i.e. via annularly arranged openings(preferably evenly distributed across the circumference of the reactor) or a ring space opening (11)with completely open(see Fig.3). Therefore, Solids that reach the reactor head with the core flow are evenly discharged via the shortest route radially in all directions. By this measure, the formation of agglomerates as well as the size of the agglomerates is reduced. In particular for fluidized bed processes operated with varying loads (gas flow rates), the invention leads to more stable operating conditions and the impact on systems arranged up- or downstream of the reactor is reduced considerably.

BRIEF DESCRIPTION OF THE DRAWINGS Further explanations to the invention are to be made with thelfgύre^'e^arnple^ in the following.

Fig.1 a structure sketch of principal design (1) of an annular space fluidized bed according to the invention Fig.2 a structure sketch of principal design (2) of an annular space fluidized bed according to the invention Fig. 3 a tridimensional sketch of an annular space gas outlet according to the invention Fig. 4 a tridimensional sketch according to the invention with an agglomerate separator Fig. 5 a simple flow diagram with a reactor according to the invention with a downstream solid matter separator and the solid recirculation passage

DETAILED DESCRIPTION? Concrete Implementation Manner

According to figure 1 or 2, the fluidizing chamber (4) of a reactor (1) consists of a conical or parabolic casing (3), which houses an insert (2), which also has a conical or parabolic shape. By this design, an annular space (4), which functions as a fluidizing chamber is created between the casing (3) and the insert (2), which produces a gas flow velocity, which either remains constant or decreases or increases depending on the geometry of the two components. Therefore, such a reactor can also be called constant flow velocity reactor.

By lowering or lifting the insert (2) in the direction of the double arrow (5) by means of an adjusting device (not displayed in detail),, the geometry of the annular space is changed, and thus the gas velocity in the fluidizing chamber is increased or decreased. So when the gas rate fed to the reactor changes, a nearly constant gas flow velocity can be achieved in the annular space by lowering or lifting the insert (2).The annular space can be implemented in such a way that increase or decrease the cross sections of the fluidizing chamber from bottom to top. (See figure 1 or 2) According to the invention, the reactor has an agglomerate separator (Fig 4), which is designed as an annular space opening(6), or as a large number of staggered openings arranged across the circumference of the fluidizing chamber of a fluidized bed reactor, or as an outlet situated in the center of the reactor. The openings of the agglomerate separator (6) can be situated either in the conical enlargement of the fluidizing chamber, immediately at the junction between the conical enlargement and the cylindrical section, in the cylindrical section of a conventional fluidized bed reactor, at any point of the nozzle bottom or at any point of the outer wall or of the inner cone of an annular space reactor. The agglomerate separator ensures that agglomerates are mainly laterally diverted before they reach the nozzle bottom in an annular trough (7). Remainders of the agglomerate, which reach the openings of the nozzle bottom, are removed from the nozzle bottom by a discharge device, which is not displayed in detail.

It is the function of the agglomerate separator to lead off the recirculating agglomerates and conglomerates from the fluidizing chamber (4). Then the solid matters can be fed to the fluidized bed again by means of controlled or uncontrolled feeders (8).

Figure 4 shows such an agglomerate separator(δ) with an annular space opening. Here, the solid matters are fed to a floating trough (7), from which they can be re-fed to the fluidized bed reactor in a controlled way, e.g. via several lines (8) evenly distributed across the circumference.

By this method, more stable operating conditions are created over broad load ranges as they are normally only possible within a smaller load range (gas flow rates). The impact on systems arranged up- or downstream of the reactor is minimized by the use of an agglomerate separator.

Figure 3 shows a reactor with annularly arranged outlet openings (11), which are preferably evenly distributed across the circumference of the reactor (1), through which the product-laden gas is discharged in radial direction and then downwards

(9), if necessary. Solids that reach the reactor head with the core flow are evenly discharged via the shortest route, and especially radially in all directions. By this measure, the formation of agglomerates as well as the size of the agglomerates is reduced. In particular for fluidized bed processes operated with varying loads (gas flow rates), the invention leads to more stable operating conditions and the impact on systems arranged up- or downstream of the reactor is reduced considerably.

The annular space outlet can be equipped with a gas guiding cone (10) (see Fig 2), which further improves the discharge of the gas / solids mixture.

The fluid bed reactor gas inlet of the invention has one or several nozzles (e.g. annular space nozzle/nozzles) or a fluidizing bottom.

See figure 5, the fluid bed reactor of the invention, connected with a downstream solid matter separator (12), which is connected with a container or a floating trough

(13) through a slide or combined as one unit (14), the separated solids are to be collected in to the separator. The container or the floating trough(13) is as well connected to the reactor (1) via passage (15), through which the collected solid

matter is returned to reactor (1) and/or discharged.

The fluid bed reactor of the invention, characterized by that the downstream solid matter separator (12) is controlled that the differential pressure of the separator is low when the gas flow is small and high when the gas flow is large.

The fluid bed reactor of the invention can be applied in the followings: a Cleaning of flue gases from furnaces or incineration plants. b Cleaning of gas mixtures of any kind. c Incineration of fuels or waste within the fluidized bed. d Catalytic, adsorptive and/or absorptive processes. e Conversion by means of chemical reactions of the matters contained in the fluidized bed.

Claims

CLAIMS:

1. Fluidized bed reactor(1), characterized by the fact that the fluidizing chamber(4) of it is equipped with inserts which make it possible to modify the cross section of the chamber in such a way that the gas velocity can be adjusted at varying or constant gas flow rates.

2. Fluidized bed reactor according to claim 1 .characterized by the fact that the fluidizing chamber (4) consists of a casing which is conical or parabolic to a vertical axis, and which houses an insert (2), which also is conical or parabolic to a vertical axis, so that an annular space which functions as the fluidizing chamber is created between the inner shell surface of the casing and the outer shell surface of the insert, and that it is provided for adjusting devices in order to adjust the position between the casing (3) and the insert (2) in axial direction to change the cross-section area of the annular space.

3. Fluidized bed reactor (1), characterized by the fact that the gas outlet is designed as annular space opening or as openings (11) distributed across the circumference of the chamber, where the gas is evenly radially discharged from the reactor.

4. Fluidized bed reactor (1), characterized by the fact that the fluid bed chamber of it has an annular space opening (6), or openings evenly distributed across the circumference, or one/several openings of any shape, which makes it possible that refluxing solids, other solids and agglomerates can be discharged out of the fluid bed chamber separately from the gas / gas stream.

5. Fluidized bed reactor (1) according to claim 4, characterized by the fact that the aforementioned opening or openings for discharging can be located inside or above the gas inlet nozzle/nozzles, or located in the bottom (consisting several nozzles or made of a fluidizing bottom) of the fluid bed chamber.

6. Fluidized bed reactor according to any one of the above mentioned claims 1 to 4, characterized by the fact that the gas inlet of the fluidized bed chamber of the reactor (1) has, one or several nozzles (e.g. annular space nozzle/nozzles) or a fluidizing bottom.

7. Fluidized bed reactor according to anyone of the claim 1 to 4, characterized by the fact that it is connected with a downstream solid matter separator(12), which is connected with a container or a floating trough(13) through a shoot pipe or as one unit (14), and where the separated solid is collected. The container or the floating trough (13) is as well connected with the reactor (1) by passage (15,) where the collected solid matter is returned to the reactor (1) and/or discharged.

8. Fluidized bed reactor according to claim 7, characterized by the fact that the aforementioned downstream solid matter separator(12) is controlled that the differential pressure of the separator is low when the gas flow is small while high when the gas flow is large.

9. Fluidized bed reactor according to anyone of the claims 1 to 4, characterized by the fact that the gas outlet of the reactor (1) has a cone-shaped insert (10).

10. Fluidized bed reactor according to anyone of the claims 1 to 4, characterized by the fact that it is set up for the execution of the following processes: a Cleaning of flue gases from furnaces or incineration plants.

b Cleaning of gas mixtures of any kind. c Incineration of fuels or waste within the fluidized bed. d Catalytic, adsorptive and/or absorptive processes, e Conversion by means of chemical reactions of the matters contained in the fluidized bed.