Bogie type furnace

Abstract

 This invention relates to a bogie type furnace having a bogie 4 movable into and out of a furnace chamber zone 3 between opposed furnace walls 1 of a main furnace structure. Known furnaces have poor sealing systems.
According to the present invention the bogie 4 has an outwardly extending edge portion with a downwardly facing surface and the main furnace structure has inwardly extending downwardly facing surfaces 9 at or in proximity to said opposed walls 1, said respective downwardly facing surfaces 9 being formed and arranged so as to be at substantially the same level and to define a small clearance 8 between their opposed free edges in an inserted operational position of the bogie 4 in the firing chamber zone 3. At least one of said bogie 4 and main furnace structure 1 is provided with a sealing means support 12 supporting an upwardly facing heat resistant sealing means 10 so as to be movable between a sealing position with said sealing means 10 in sealing engagement with said downwardly facing surfaces 9 of both the bogie 4 and main furnace structure 1 to seal the clearance 8 therebetween and an open position in which said sealing means 10 is spaced from said downwardly facing surfaces 9.

Description

[0001] This invention relates to bogie type furnaces and in particular to such furnaces with improved bogie-to-furnace seals.

[0002] In bogie type furnaces the floor of the furnace chamber is constituted at least partly by a bogie which is movable into and out of the furnace between opposed furnace walls. In order to enable the bogie to be able to move relatively easily between the opposed furnace walls it is necessary to provide a clearance between the bogie and the furnace walls. On the other hand during firing in the chamber it is necessary to closely seal this clearance to prevent the escape of heat and gases therethrough and possible damage to unprotected parts of the bogie structure and/or other elements in the vicinity.

[0003] In conventional furnaces of the above type there are used sand seals comprised by channels provided at the outside edges of the bogie and filled with sand, the furnace being provided with downwardly depending flanges disposed so as to extend downwardly into the sand and plough through the sand in the channels as the bogie passes in the furnace. These seals are however on the one hand unable to provide a close gas-tight seal or withstand any elevated pressure and on the other hand are subject to substantial disturbance during opening and closing and movement of the bogie and thus require constant monitoring and topping-up to replace lost sand.

[0004] It is an object of the present invention to provide a bogie type furnace with an improved bogie-to-furnace sealing means.

[0005] The present invention provides a bogie type furnace having a bogie movable into and out of a furnace chamber zone between opposed furnace walls of a main furnace structure, characterised in that
said bogie has an outwardly extending edge portion with a downwardly facing surface and said main furnace structure has inwardly extending downwardly facing surfaces at or in proximity to said opposed walls, said respective downwardly facing surfaces being formed and arranged so as to be at substantially the same level and to define a small clearance between their opposed free edges in an inserted operational position of the bogie in the firing chamber zone, at least one of said bogie and main furnace structure being provided with a sealing means support supporting an upwardly facing heat resistant sealing means and movable between a sealing position with said sealing means in sealing engagement with said downwardly facing surfaces of both the bogie and main furnace structure so as to seal the clearance therebetween and an open position in which said sealing means is spaced from said downwardly facing surfaces.

[0006] Advantageously the heat resistant sealing means is of a flexible ceramic fibre material.

[0007] Preferably the sealing means support is mounted on the main furnace structure and is provided with remote drive means operable from the exterior side of the furnace walls for moving said support and sealing means between said open and sealing positions.

[0008] By means of the present invention it is possible to achieve a very close sealing between the bogie and the main furnace structure by virtue of the flexible nature of the highly heat resistant ceramic fibre seal which is readily able to accommodate minor irregularities in the surfaces of the flanges and can be tightly clamped against these surfaces. At the same time the seal is substantially maintenance free and has an extended life.

[0009] Further preferred features and advantages of the present invention will appear from the following description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawings in which:

Fig. 1 is a schematic plan view illustrating a sealing means of the invention and its mode of installation in a bogie type furnace; and

Fig. 2 is a detail transverse quasi-sectional view of the arrangement of Fig. 1.

Fig. 1 is a schematic plan view of a bogie type furnace but with most of the main furnace body and the whole of the bogie itself omitted in order to clearly show the construction of the sealing means and support structure and clamping arrangement.

Fig. 2 is a detail end view showing the clearance between the main furnace body and the bogie and the disposition of the sealing means and support therefor, relative to the clearance gap.

[0010] More specifically Fig. 2 shows part of one side wall 1 of a main furnace body with a refractory lining 2 in the region of a firing chamber zone 3. Part of a bogie 4 is shown in an inserted position between said side wall 1 and the opposed side wall.(not shown), the main platform 5 of the bogie 4 which has a refractory lining 6 forming the floor 7 of said firing chamber zone 3.

[0011] As may be clearly seen in Fig. 2 the bogie is dimensioned relative to the main furnace body so that 'there is a small clearance 8 on each side between the outer edge of the bogie platform 5 and the bottom of the opposed side wall lining 2 and an adjacent support flange 9. These clearances 8 enable free movement of the bogie 4 into and out of the firing chamber zone in the furnace.

[0012] In order to seal these clearances 8 there are provided respective sealing means in the form of ceramic fibre seals 10 mounted in upwardly facing U-shaped channel sections 11 which in turn are supported on a plurality of outwardly extending support arms 12 at inner ends 13 thereof. The outer ends 14 of the support arms 12 on each side of the furnace are non-rotatably secured to a respective drive connection rod 15 with the aid of keys 16.

[0013] The connection rods 15 extend along the outside walls of the furnace on which they are supported via suitable bearing means 36. On each side of the furnace a connecting arm 17 has a first end 18 likewise non-rotatably connected to a respective connecting rod 15 with the aid of a key. (not shown) and a second end 19 pivotally connected 20 to the distal end 21 of a piston rod 22 of a pneumatic piston and cylinder drive means 23. The cylinder 24 of the drive means 23 is pivotally connected 25 to a support bracket 26 provided on the respective outside wall of the furnace. As may be seen in Fig. 2 the support arms 12 and connecting arms 17 though laterally displaced from one another along the length of the rod function together as a bell crank lever so that in the extended position of the piston and cylinder 23 with the outer end 19 of the connecting arm held downwardly the inner ends 13 of the support arms 12 exert an upward pressure on the channel 11 to hold the seal tightly against the undersides of the opposed outer edges 5 of the bogie platform and the inward bottom edge of the refractory lining 2 and adjacent flange 9 bridging the clearance 8 therebetween and thus sealing it against the passage of hear or gases from the firing chamber zone therebetween. Due to the flexible nature of the ceramic fibre seal 10 it is possible to obtain a substantially tight sealing even in the presence of minor surface imperfections in the seal engaging surfaces of the bogie and main furnace body. In order to facilitate this close sealing the seal lO projects upwardly from the channel 11 for a short distance - approximately 38mm in the embodiment shown.

[0014] When it is desired to withdraw the bogie from the firing chamber zone the piston rods 22 are retracted on each side of the furnace to swing the support arms 12 down and bring the seal 10 into a position well clear of the bogie. The bogie can now be freely withdrawn without the risk of damage to the seals 10. In order to prevent any such damage occurring inadvertently the control means for the piston-and-cylinder drive means 23 are interlinked with the bogie drive means so as to prevent operation of the latter when the seals 10 are in their upper, sealing, positions.

[0015] The ceramic fibre door seal means used in accordance with the invention is a known material used at present for lining the interior of furnaces. In general it is in the form of a more or less densely packed arrangement of upstanding ceramic fibres on a flexible backing of for example a heat resistant cloth which may be cemented to the channel or directly or indirectly on a more or less rigid heat resistant substrate which may be conveniently bolted to the channel. This type of material is commercially available from Messrs. Clinotherm Ltd. of Dewsbury, Yorkshire, England and is made in various thicknesses e.g. from 40 to 125mm and various temperature grades e.g. heat resistant up to 1100°C and heat resistant up to 1500°C.

Claims

1. A bogie type furnace having a bogie.(4) movable into and out of a furnace chamber zone.(3) between opposed furnace walls.(1) of a main furnace structure, characterised in that said bogie.(4) has an outwardly extending edge portion with a downwardly facing surface and said main furnace structure has inwardly extending downwardly facing surfaces.(9) at or in proximity to said opposed walls.(l), said respective downwardly facing surfaces.(9) being formed and arranged so as to be at substantially the same level and to define a small clearance.(8) between their opposed free edges in an inserted operational position of the bogie (4) in the firing chamber zone.(3), at least one of said bogie.(4) and main furnace structure.(1) being provided with a sealing means support.(12).supporting an upwardly facing heat resistant sealing means.(lO) and movable between a sealing position with said sealing means (10) in sealing engagement with said downwardly facing surfaces (9) of both the bogie . (4) and main furnace structure.(1) so as to seal the clearance (8) therebetween and an open position in which said sealing means .(10) is spaced from said downwardly facing surfaces.(9).

2. A furnace as claimed in claim 1 wherein the heat resistant sealing means.(10) is of a flexible ceramic fibre material.

3. A furnace as claimed in claim 2 wherein the sealing means.(10) is supported in a channel.(11) so as to project upwardly from said channel.

4. A furnace as claimed in claim 2 or claim 3 wherein the sealing means.(10) is in the form of a more or less densely packed arrangement of upstanding ceramic fibres on a flexible backing.

5. A furnace as claimed in any one of claims 1 to 4 wherein the sealing means support.(12) is mounted on the main furnace structure and is provided with remote drive means (15, 23) operable from the exterior side of the furnace walls.(1) for moving said support.(12) and sealing means (10) between said open and sealing positions.

6. A furnace as claimed in claim 5 wherein said drive means comprises a pressurised fluid operated piston and cylinder means.(23) and a mechanical linkage.(17) therefrom to the sealing means support.(12).

Drawing