Furnace having toroidal fluid flow heating zone

Details Furnace having toroidal fluid flow heating zone Furnace having toroidal fluid flow heating zone

1999-10-04

2000-10-31

Wilson, Pamela

Heating

With heating gas conveying, agitating, scattering or...

432 77, 432101, 34179, F27B 1502

Patent

active

061393134

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to furnaces. In particular, it relates to furnaces of the kind in which a toroidal fluid flow heating zone is established. Such furnaces are described, for example, in U.S. Pat. No. 4,479,920.
Generally, a hot gas is passed through gaps between angled blades or vanes in a ring of blades or vanes provided in an operational chamber of the furnace. The blade ring is formed in an annular gap between the wall of the chamber and a central block, for example, an upwardly pointing conical portion, located on the axis of the chamber. Gas flow is caused to follow a rotary path in a doughnut shaped region around the block and in individual swirls within the rotary path. This ensures efficient residence of, and heat transfer to, material, such as particulate material, to be heated in the gas flow.


SUMMARY OF THE INVENTION

Furnaces of the said kind may be used for the heat treatment of particulate material. However, it has been found that where the feed particulate material comprises material which fluxes at temperatures at which it is to be heat treated, unwanted build up of the fluxed material occurs in various parts of the furnace, especially on or around the ring of angled blades and on or around the central block. As illustrated hereinafter, such build up can cause a back pressure to occur which impedes the particulate feed system and/or extinguishes the burner employed to provide the hot gas. Furthermore, such build-up of material requires removal before the furnace can be suitably operated again. This necessitates terminating the use of the furnace and undesirably limits the duration of that use. Such limitations make prior art furnaces of the above kind unsuitable for some continuous heat treatment processes.
According to a first aspect of the present invention there is provided a furnace of the kind in which a toroidal fluid flow heating zone may be established, the furnace including a chamber in which there is provided an inner block, and a ring of angled blades between the inner block and an inner wall of the chamber; means for delivering fluid into the chamber in such a way that the fluid passes through gaps between the blades and establishes a toroidal fluid flow heating zone in the chamber above the ring of angled blades; means for injecting feed particulate material into the chamber in a region where the toroidal fluid flow is to be established; and means for injecting fuel into the chamber in a region above the ring of angled blades such that the region in the chamber at which the heating zone in the chamber is established is elevated above the ring of angled blades.
The fuel injected by such means may be reacted with a reacting fluid delivered into the chamber in the usual manner through the gaps between the angled blades. For example, the fuel may be a combustible fuel and the reacting fluid may be air or an oxygen containing fluid, whereby, if sufficient oxygen is available at a suitable elevated temperature, spontaneous reaction of the fuel and oxygen takes place to provide the required heating zone. This may constitute a plasma in part of, for example, in the upper part of, the toroidal flow.
One advantage of this aspect of the present invention is that the delivery of excessively hot gas to the operational chamber via the ring of angled blades can be avoided. This avoids damage to the ring of angled blades and neighbouring components and also avoids unwanted accretion of material being processed on the hot surfaces. By contrast, in prior art furnaces where a rapid throughput of material is required to be processed, the energy demands of the furnace are considerably raised and hot gas at a temperature as high as 1600.degree. C. to 1700.degree. C. might need to be delivered via the ring of angled blades. Such high temperatures can cause damage to the ring.
In a preferred embodiment of the present invention the reacting fluid may be delivered at a temperature in the range from 700.degree. C. to 900.degree. C., and especially from 700.degre

REFERENCES:
patent: 3889393 (1975-06-01), Thomas et al.
patent: 4025293 (1977-05-01), Beckenbach
patent: 4076493 (1978-02-01), Gardner
patent: 4559719 (1985-12-01), Dodson

Affiliated with

Also associated with

Rating

Furnace having toroidal fluid flow heating zone does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Furnace having toroidal fluid flow heating zone, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Furnace having toroidal fluid flow heating zone will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2044866