US3914876A

US3914876A - Fluidized bed apparatus

Info

Publication number: US3914876A
Application number: US443789A
Authority: US
Inventors: Thomas George Callcott
Original assignee: Broken Hill Proprietary Company Pty Ltd
Current assignee: Broken Hill Proprietary Company Pty Ltd
Priority date: 1973-02-22
Filing date: 1974-02-19
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28
Also published as: CA1030730A; JPS5335786B2; JPS5024162A; DE2408720B2; DE2408720A1; FR2218933B1; FR2218933A1; BE811404A; DE2408720C3

Abstract

This specification discloses improvements in fluidized bed apparatus of the type including a treatment channel adapted to contain a bed of particulate material, means at one end of the treatment channel for feeding compacts into the bed of carrier, means for fluidizing the bed of carrier in such a manner as will result in the transport of carrier and compacts to the other end of the treatment channel, a plurality of means for the withdrawal of carrier from the treatment channel, means for reheating and/or mixing the carrier withdrawn from the treatment channel, a plurality of means for the return of carrier from said reheating and/or mixing means to the treatment channel, and means at the other end of the treatment channel for discharging compacts and/or carrier from the treatment channel, and wherein the reheater/mixer is located at an elevated position relative to the treatment channel and the carrier withdrawal means discharge into a carrier collector bin to which is connected a pneumatic carrier lifter which returns the carrier to the reheater/mixer.

Description

[ 1 Oct. 28, 1975 FLUIDIZED BED APPARATUS [75] Inventor: Thomas George Callcott, Mayfield,

Australia [73] Assignee: The Broken Hill Proprietary Co.,

Ltd., Melbourne, Australia [22] Filed: Feb. 19, 1974 [21] Appl. No.: 443,789

[30] Foreign Application Priority Data Feb. 22, 1973 Australia 2374/73 [52] US. Cl. 34/57 A; 34/57 C; 165/107; 432/15 [51] Int. Cl. F26B 17/00 [58] Field of Search 34/57 A, 57 R, 10, 11,

34/10 Z, 57 C; 432/15, 58; 165/107; 23/2883 S, 284

Primary ExaminerKenneth W. Sprague Assistant Examiner-James C. Yeung Attorney, Agent, or Firm-Cushman, Darby & Cushman [57] ABSTRACT This specification discloses improvements in fluidized bed apparatus of the type including a treatment channel adapted to contain a bed of particulate material, means at one end of the treatment channel for feeding compacts into the bed of carrier, means for fluidizing the bed of carrier in such a manner as will result in the transport of carrier and compacts to the other end of the treatment channel, a plurality of means for the withdrawal of carrier from the treatment channel, means for reheating and/or mixing the carrier withdrawn from the treatment channel, a plurality of means for the return of carrier from said reheating and/or mixing means to the treatment channel, and means at the other end of the treatment channel for discharging compacts and/or carrier from the treatment channel, and wherein the reheater/mixer is located at an elevated position relative to the treatment channel and the carrier withdrawal means discharge into a carrier collector bin to which is connected a pneumatic carrier lifter which returns the carrier to the reheater/mixer.

9 Claims, 4 Drawing Figures U.S. Patent Oct.28, 1975 Sheet 1 of3 3,914,876

us; Patent Oct.28,1975 sheet ofs 3,914,876

\ ammntcuumumummigg HIHI FLUIDIZED BED APPARATUS This invention relates to a fluidized bed apparatus, and more particularly to improvements in the apparatus described in co-pending Application Ser. No. 317,765.

The preferred form of apparatus described in the specification of the above application includes a treatment channel containing a fluidized bed of sand and a sand reheater located adjacent the treatment channel, the sand being transferred from reheater to treatment channel and vice versa by fluidized downcomers and downcomer/sand lifters alternating along the division between the treatment channel and reheater. After being heated or otherwise treated in the apparatus, the products are discharged for further treatment. In the case of coal briquettes, the semi-coked briquettes are fully coked in a shaft furnace.

While the apparatus described works satisfactorily, it is not the most advantageous arrangement where the shaft furance can accept more briquettes than can be treated by one or two fluidized bed carbonisers. Here it would be advantageous to have a battery of carbonisers side by side with a spacing less than the width of the reheater between the adjacent carbonisers.

Furthermore, the arrangement of the transfer means between the bed and reheater renders difficult access to the transfer means for servicing and other purposes.

It is one object of this invention to provide a fluidized bed-reheater arrangement by means of which a battery of carbonisers may be formed with a minimal spacing between adjacent carbonisers.

It is another object to provide an improved means of transferring the sand or other carrier between the fluidized bed treatment channel and the reheater.

In one aspect the invention provides in a fluidized bed apparatus comprising a treatment channel adapted to contain a bed of particulate carrier, means at one end of the treatment channel for feeding compacts into the bed of carrier, means for fluidizing the bed of carrier in such a manner as will result in the transport of carrier and compacts to the other end of the treatment channel, a plurality of means for the withdrawal of carrier from the treatment channel, means for reheating and/or mixing the carrier withdrawn from the treatment channel, a plurality of means for the return of carrier from said reheating and/or mixing means to the treatment channel, and means at the other end of the treatment channel for discharging compacts and/or carrier from the treatment channel; the improvement comprising said means for reheating and/or mixing the carrier withdrawn from the treatment channel being located at an elevated position relative to said treatment channel, and a carrier collector/lifter common to at least a plurality of said withdrawal means for returning the carrier to said reheater and/or mixer means.

A preferred form of the invention will now be described with reference to the accompanying partly schematic drawings in which:

FIG. 1 is a sectional end elevation through the apparatus at one sand introducing downcomer;

FIG. la is a sectional view of the apparatus of FIG. 1 taken along lines A--A of FIG. 1.

FIG. 2 is a similar elevation at one sand withdrawal downcomer and schematically showing part of the sand collection means, and

FIG. 3 is a sectional side elevation through the reheater and schematically showing the collection means and the sand lifter.

Referring to the drawings the sand reheater l is located at an elevated position with respect to the treatment channel 2, both of which are similar in principle to the same parts of said co-pending application, being fluidized by gas distributor pipes 4. The treatment channel 2 has a product and cool sand introduction section 5 (FIG. 3) similar in principle to the alternative arrangement described in said co-pending application. Details described in said co-pending application have been omitted from the present drawings and it is to be understood that the apparatus is basically the same except for the position of the reheater l and the means by which sand is transferred.

The side wall 6 of the channel 2 extends upwardly to define one side wall 7 of the reheater 1. At a plurality of spaced positions along the length of the channel 2 and reheater 1, the

walls

6 and 7 are formed with a downcomer passage 8. The passage 8 extends from the top of wall 7 to the position in wall 6 adjacent the floor of channel 2. A sand entry opening 9 to the reheater 1 is formed in wall 7 while an exit opening 10 to the bed is formed in wall 6. Both openings can be inspected through ports P, as can passage 8, and a gas distributor pipe 11 extends through the bottom port to fluidize the downcomer passage 8 between openings 9 and 10. Thus, sand is transferred by fluidized dense phase flow between the reheater 1 and the channel 2 via the downcomer when the downcomer 8 and the bed in the treatment channel 2 are fluidized.

The side wall 6 of the channel is also formed with downcomer passages 12 at a plurality of positions along the bed, alternating with passages 8. A sand entry opening 13 into the bed is formed in the wall 6, and again an inspection port P is provided. Each passage 12 opens through the bottom of the side wall 6 where it is connected to a pipe 14.

The pipes 14 discharge through a fluidized valve V to a collector trough 15 that is formed with weir windows 16 at each pipe position. When the fluidized valve V is activated, sand flows through weir windows 16 and into a fluidized sand slide 17.

The slide 17 terminates at a weir 18 over which the sand is discharged into a bin 19. The sand is then returned to the reheater 1 via a pneumatic lifter tube 20. The sand feed into the lifter is by fluidized dense phase vertical pipe flow and out of it by lean phase pneumatic transport. The sand travels vertically in the sand lifting pipe by lean phase pneumatic transport and then changes to horizontal lean phase pneumatic transport before returning to the reheater chamber 1.

The apparatus described above was simulated by means of an experimental rig which verified the sand ciculation system shown in the drawings. The test rig incorporated an automatic temperature activated control mechanism for the equivalents of

downcomers

8 and 12. The fluidizing gases in the channel 2, downcomers l2 and air slide 17, as well as the briquette volatile gases from channel 2 were exhausted by a cyclone system. A similar cyclone system was provided for the gases from the reheater downcomers 8 and sand lifter 20. These systems are not shown in the drawings for the sake of clarity.

Means (not shown) may be provided in or near the tube 20 for reheating the sand as it is lifted. For example, a fuel may be combusted with part of the lifting air in the lifter 20 while the sand is pneumatically lifted to reduce the heating necessary in the reheater. In a battery operation, one or more lifters 20 may be arranged to heat the sand as above while others simply lift the cool sand. The two sands would then be intimately admixed in the fluidized reheater. It may be possible to reheat the sand sufficiently in the lifters, the reheater 1 then being used only as a mixer. The reheater may then be operated at a lower temperture, for example 550 to 750C, preferably 650C, than is possible when the reheater is used as such, e.g. 700 to 800C. In this way requirements on structural materials are eased. Part of the cool and/or reheated sand may be discharged from the lifters to the feed section of channel 2.

It will be appreciated that the positioning of the reheater as shown allows access to the downcomers at the inlet and outlet positions. This was not possible with the apparatus of said co-pending application. It will also be appreciated, that independently of the position of the reheater, the downcomer sand lifter arrangement offers advantages over the arrangement described in said copending application in that greater control over sand flow is possible. Furthermore a better balance between supply and removal of carrier to and from the channel is possible through the use of downcomers for both operations.

The reheater 1 need not be arranged at the side of the channel 2 as shown but may be more or less directly above the channel 1, the flue F for off-gas in the channel 2 extending between a space between the channel and reheater.

A battery of two or more of the described arrangements may be arranged in use at either side of the mouth of a shaft furnace for delivering semi-coked briquettes thereto. In an arrangement of three such carbonisers, the sand lifters may discharge into more than one reheater or into a large single reheater arranged above the battery of treatment channels.

Where the battery consists of several treatment channels having reheaters thereabove, there need be no space between adjacent channells. In such a battery the inspection ports for the outermost channels reheater combinations may be directed outwardly while inspection of the inner downcomers may be achieved from the top ports P.

In another arrangement, introducing and withdrawal means may be arranged on either or both sides of the channel 2 and/or reheater 1 with a single reheater servicing two adjacent channels.

I claim:

1. In a fluidized bed apparatus comprising a treatment channel adapted to contain a bed of particulate carrier, means at one end of the treatment channel for feeding compacts into the bed of carrier, means for fluidizing the bed of carrier in such a manner as will result in the transport of carrier and compacts to the other end of the treatment channel, a plurality of means for the withdrawal of carrier from the treatment channel, carrier temperature changing means for changing the temperature of the carrier withdrawn from the treatment channel, a plurality of means for the return of carrier from said carrier temperature changing means to the treatment channel, and means, different from said withdrawal means, at the other end of the treatment channel for discharging compacts and/or carrier from the treatment channel; the improvement comprising said carrier temperature changing means being located at an elevated position relative to said treatment channel and a carrier collector/lifter means common to at least a plurality of said withdrawal means for returning the withdrawn carrier to said carrier temperature changing means.

2. The improvement of claim 1, wherein said carrier lifter means comprises a pneumatic lifter tube and means are provided for reheating the carrier as it is lifted to the carrier temperature changing means.

3. The improvement of claim 2 wherein means are provided for combusting a fuel with part of the air used for lifting the carrier in the lifter tube.

4. The improvement of claim 1, wherein said carrier returning means comprise a plurality of generally vertical downcomers fluidized to cause fluidized dense phase flow of the carrier in said downcomers.

5. The improvement of claim 4, wherein said downcomers comprise passages in a side wall of said carrier temperature changing means and a side wall of said treatment channel, said side walls being formed as a common wall.

6. The improvement of claim 1, wherein said carrier collector/lifter means includes a carrier slide into which said withdrawal means discharge, and a carrier collection bin arranged at the outlet end of said slide.

7. The improvement of claim 1, wherein said carrier withdrawing means comprise generally vertical downcomers fluidized to cause fluidized dense phase flow in said downcomers by means of a fluidized valve near the outlet ends of said downcomers.

8. In a fluidized bed apparatus comprising a treatment channel adapted to contain a bed of particulate carrier, means at one end of the treatment channel for feeding compacts into the bed of carrier, means for fluidizing the bed of carrier in such a manner as will result in the transport of carrier and compacts to the other end of the treatment channel, a plurality of means for the withdrawal of carrier from the treatment channel, temperature changing means for changing the temperature of the carrier withdrawn from the treatment channel, a plurality of means for the return of carrier from said temperature changing means to the treatment channel, and means at the other end of the treatment channel for discharging compacts and/or carrier from the treatment channel; the improvement comprising said withdrawal means being connected to a carrier collection means common to at least a plurality of said withdrawal means, and a carrier lifter connected to said collection means for returning said carrier to said temperature changing means.

9. In a fluidized bed apparatus comprising a generally horizontal treatment channel adapted to contain a bed of particulate carrier means at one end of the treatment channel for feeding compacts into the bed of carrier, means for fluidizing the bed of carrier in such a manner as will result in the transport of carrier and compacts to the other end of the treatment channel, a plurality of transfer means of two types disposed along the treatment channel one type being for the removal of carrier from the channel and the other type being for the return of carrier to the treatment channel, a device for changing the temperature of the carrier removed from the treatment channel prior to its return to the treatment channel, said transfer means of said one type including a passage connected to the temperature changdischarging compacts and/or carrier from the treatment channel, the improvement comprising said temperature changing device being located at an elevated position relative to said treatment channel, and a carrier collector/lifter means common to at least a plurality of said transfer means of said one type for returning the withdrawn carrier to said temperature changing de vice.

Claims

9. In a fluidized bed apparatus comprising a generally horizontal treatment channel adapted to contain a bed of particulate carrier means at one end of the treatment channel for feeding compacts into the bed of carrier, means for fluidizing the bed of carrier in such a manner as will result in the transport of carrier and compacts to the other end of the treatment channel, a plurality of transfer means of two types disposed along the treatment channel one type being for the removal of carrier from the channel and the other type being for the return of carrier to the treatment channel, a device for changing the temperature of the carrier removed from the treatment channel prior to its return to the treatment channel, said transfer means of said one type including a passage connected to the temperature changing device and having an outlet opening into the treatment channel at or near the base or floor thereof while the transfer means of said other type includes a passage having its inlet opening to the channel just below the top of the bed, whereby the carrier from the temperature changing device passes upwardly through the channel in a direction which is transverse to the direction of transport of the compacts and carrier, and means at said other end of the treatment channel for discharging compacts and/or carrier from the treatment channel, the improvement comprising said temperature changing device being located at an elevated position relative to said treatment channel, and a carrier collector/lifter means common to at least a plurality of said transfer means of said one type for returning the withdrawn carrier to said temperature changing device.