GB2268261A

GB2268261A - Fluid used bed reactor with removable heat exchanger

Info

Publication number: GB2268261A
Application number: GB9313029A
Authority: GB
Inventors: Hans-Juergen Weiss; Juergen Emmel; Wolfgang Frank; Wladislaw Lewandowski; Wolfgan Scheler
Original assignee: Metallgesellschaft AG
Current assignee: GEA Group AG
Priority date: 1992-06-26
Filing date: 1993-06-24
Publication date: 1994-01-05
Anticipated expiration: 2013-06-24
Also published as: AU4149793A; DE4220952C2; DE4220952A1; GB2268261B; GB9313029D0; AU666016B2

Abstract

A fluidized bed reactor comprises at least two heat exchanger units, each of which comprises a pipe plate 9, which is separably fitted in an aperture 15 in the reactor wall. The inlet and outlet ends of a plurality of fluid- conducting pipes 10, 11 extend through each pipe plate. At least one of the pipe plates is preferably provided with an entrance chamber 10b, 11b adjacent to the inlet ends of the pipes and with an exit chamber 10c, 11c adjacent to the exit ends of the pipes. <IMAGE>

Description

2268261 FLUIDIZED BED REACTOR FOR COOLING OR HEATING GRANULAR SOLIDS BY AN

INDIRECT HEAT EXCHANGE This invention relates to a fluidized bed reactor for the thermal treatment of granular solids, comprising piping contained in the reactor within the fluidized bed and serving to conduct a heating or cooling fluid for effecting an indirect heat exchange between the heating or cooling fluid and the solids.

Such a fluidized bed reactor is known, e.g., from German Patent 29 01 723 and the corresponding U.S. Patent 4,295,281, and from German Patent 36 44 806. In the known fluidized bed reactors, granular solids, particularly brown coal, are heated and are thus substantially dried. The reactors comprise fixedly installed piping, through which flows a heating fluid, such as steam, in order to supply the required energy to the fluidized bed.

It is an object of the invention so to design the fluidized bed reactor described first hereinbefore that individual sections of the piping can be disconnected and can be replaced without a large expenditure. This is accomplished in accordance with the invention in that the reactor comprises at least two spaced apart pipe plates, which are detachably fitted in apertures in the reactor wall, the inlet and outlet ends of a plurality of fluidconducting pipes extend through each pipe plate, and each pipe plate and the associated pipes constitute a heat exchanger unit.

A fluidized bed reactor in accordance with the invention may be used to cool or heat the granular solids of the fluidized bed. If the fluidized bed is to be heated, a heating fluid, such as a hot gas, steam or a hot liquid, will be conducted through the pipes. If the fluidized bed 2 is to be cooled, a cooling fluid, such as water, will be supplied to the pipes.

At least one of the pipe plates is desirably provided adjacent to the inlet ends of the pipes with an entrance chamber and in that case at least one of the pipe plates is provided with an exit chamber adjacent to the outlet ends of the pipes. Adjacent pipes of a given heat exchanger unit are desirably approximately evenly spaced apart. The pipes which are associated with different pipe plates, and therefore belong to different heat exchanger units, need not be parallel but may extend at any desired angle to each other.

According to a further feature of the invention at least two adjacent heat exchanger units comprise pipe plates fitted in the reactor wall in apertures which are obliquely opposite to each other. Briefly stated, such heat exchanger units extend approximately opposite to each other. If it is desired to accommodate in the reactor as many pipes as possible per cubic meter of fluidized bed volume, alternate heat exchangers arranged on the same level will extend opposite to each other. In that case it will be possible to provide on a given level, e.g. 10 to 50 heat exchanger units which extend alternately opposite to each other.

The invention will now be described further with reference to the accompanying drawings, in which: Figure 1 is a schematic longitudinal sectional view showing a fluidized bed reactor in accordance with one embodimentof the present invention; 30 Figure 2 is a longitudinal sectional view taken on line A-A in Figure 3 and showing two heat exchanger units; 3 Figur;a 3 is a transverse sectional view taken on line B-B in Figure 2; and Figure 4 is a longitudinal sectional view taken on line C-C in Figure 3.

The fluidized bed reactor 1 shown in Figure 1 comprises vertical outside walls la and lb, which enclose a fluidized bed 2. Fluidizing gas is supplied under pressure through a line 3 and is distributed into the fluidized bed 2 through a grate 4 provided with orifices. The granular solids which are to be thermally treated are supplied to the fluidized bed through line 5. Treated solids are withdrawn from a collecting chamber 6 below the orificed grate 4 and are removed in a line 7 from the reactor.

Solids-containing fluidizing gas leaves the reactor in a duct 8 and enters dedusting means, which are known per se and are not shown and which may consist e.g., of a cyclone and/or an electrostatic precipitator. The solids which have been separated from the fluidizing gas may be removed as treated solids from the process or may be recycled to the fluidized bed 2 entirely or in part; this has also not been shown in the drawing.

In the subsequent description it will be assumed that heat is indirectly supplied to the fluidized bed 2 by a heating fluid, which flows in the fluidized bed through pipes 10 and 11. Analogously, a cooling fluid might be conducted through the pipes. The heating fluid is supplied from the outside in lines 10a and 11a and then f irst enters an entrance chamber 10b or 11b before it f lows through the associated pipes. At the outlet end of the pipes, an associated exit chamber loc or 11c is provided, from which the cooled heating fluid is discharged in lines 10d and 11d. The components designated by the reference characters 10, 10a, 10b, 10c and 10d belong to the upper heat exchanger unit, and the components designated by the 4 reference characters 11, lla, llb, ilc and lid belong to a second heat exchanger unit disposed below the first. The pipes of both units have a gradient throughout their length so that a liquid contained therein will always be drained.

Figures 2 and 3 illustrate how two or more heat exchanger units may be designed and how they may be arranged, e.g. in the reactor. Each unit can be separately turned on and off and when the reactor has been shut down each unit can be removed from the reactor. As a result, servicing work can be performed more quickly and will be simplified. In Figure 2 a part of the lower unit comprising the pipes 11 has been removed from the reactor.

Each unit comprises a pipe plate 9, see Figures 2 and 3, through which the inlet and outlet ends of the pipes associated with the unit extend. In Figure 1 the pipe plates 9 have been omitted for the sake of simplicity.

The pipe plate is f itted in an aperture 15 in the side wall of the reactor and is separably joined to that wall, e.g. by bolting or welding. The pipe plate 9 is so shaped that it will entirely fill the aperture 15 so that the inside surface of the reactor wall is as smooth as possible there. In case of such a smooth inside surface, the formation of crusts as well as disturbances in the distribution of the fluidizing gas will be avoided. The entrance chambers 10b and llb and the exit chambers 10c and llc explained with reference to Figure 1 are provided on the outside of the tube plate 9.

The pipes are schematically represented as simple lines in Figures 1 to 4. It will be understood that the number of pipes included in a heat exchanger unit may be selected substantially as desired.

It is apparent from Figures 2 and 3 that the tube plates 9 of adjacent, i. e. juxtaposed or superposed, heat exchanger units 9 are f itted in the reacto r walls la and 1b in apertures 15 which are obliquely opposite to each other so that the distance between adjacent units may be rather small.

Figure 3 shows an important modification of the invention. Alternate heat exchanger units disposed on the same level extend opposite to each other and may be stated to alternate on the same level. In that case the pipes 10 of the upper unit in Figure 3, the pipes 12 of the intermediate unit and the pipes 13 of the lower unit in Figure 3 can be closely packed in the fluidized bed on the same level.

It may be suf f icient in practice to provide only juxtaposed units (corresponding to pipes 10, 12 and 13 in Figure 3) in the fluidized bed reactor and to omit other, lower units (pipes 11 of Figures 1 and 2).

If the pipes have a gradient throughout their length, the most closely adjacent pipes 12, 13 of adjacent units will be very close to each other at certain locations indicated by a circle 2 0 in Figure 4. Care must be taken in practice that the distance between adjacent pipes at said locations is larger than the largest particle diameter which may occur in the fluidized bed so that particles will not be clamped and retained between the pipes.

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Claims

CLAIMS:

1. A fluidized bed reactor for the thermal treatment of granular solids, comprising piping contained in the reactor within a zone thereof in which a fluidized bed is to be formed and serving to conduct a heating or cooling fluid for effecting an indirect heat exchange between the heating or cooling fluid and the solids of the fluidized bed, characterized in that the reactor comprises at least two spaced apart pipe plates which are detachably fitted in apertures in the reactor wall, the inlet and outlet ends of a plurality of fluid-conducting pipes extend through each pipe plate, and each pipe plate and the associated pipes constitute a heat exchanger unit.

2. A fluidized bed reactor according to Claim 1, characterized in that at least one of the pipe plates is provided with an entrance chamber adjacent to the. inlet ends of the pipes.

3. A fluidized bed reactor according to Claim 1 or Claim 2, characterized in that at least one of the pipe plates is provided with an exit chamber adjacent to the outlet ends of the pipes.

4. A fluidized bed reactor according to any of Claims 1 to 3, characterized in that adjacent pipes of a heat exchanger unit are spaced a pproximately equal distances apart.

5. A fluidized bed reactor according to any of Claims 1 tc;'4, characterized in that the pipe plates of at least two adjacent heat exchanger units are fitted in the reactor wall in apertures which are obliquely opposite to each other.

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6. A fluidized bed reactor according to Claim 5, characterized in that adjacent heat exchanger units disposed on the same level extend opposite to each other.

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7. A fluidized bed reactor, substantially as hereinbefore described with reference to the accompanying drawings.