Start-up torch

Abstract

An apparatus includes a tuyere including a tubular chamber having an internal wall defined by a mandrel; a plasma torch assembly including a torch positioned to inject hot gas into the tuyere and having a tubular structure that extends along an axis of the chamber; the plasma torch assembly further including a shroud head configured to inject shroud gas between the internal wall of the chamber and the tubular structure of the torch; a pipe positioned around at least a portion of the mandrel forming a plenum at least partially encircling the mandrel; and a plurality of nozzles in the chamber internal wall configured to inject a combustible material from the plenum to a space between the internal wall of the chamber and the tubular structure of the torch.

What is claimed is: 
     
         1 . An apparatus comprising:
 a tuyere including a tubular chamber having an internal wall defined by a mandrel;   a plasma torch assembly including a torch positioned to inject hot gas into the tuyere and having a tubular structure that extends along an axis of the chamber and includes an end positioned adjacent to an outlet end of the chamber;   the plasma torch assembly further including a shroud head configured to inject shroud gas between the internal wall of the chamber and the tubular structure of the torch in a direction tangentially disposed with respect to the chamber wall;   a pipe positioned around at least a portion of the mandrel forming a plenum at least partially encircling the mandrel; and   a plurality of nozzles in the chamber internal wall configured to inject a combustible material from the plenum to a space between the internal wall of the chamber and the tubular structure of the torch, wherein the plurality of nozzles are configured to deliver the combustible material upstream of a plasma plume produced by the torch allowing premixing of the shroud gas and the combustible material in the space between the internal wall of the chamber and the tubular structure of the torch prior to ignition by the plasma plume.   
     
     
         2 . The apparatus of  claim 1 , wherein the shroud gas follows a helical path in the space between the internal wall of the chamber and the tubular structure of the torch. 
     
     
         3 . The apparatus of  claim 1 , wherein the shroud head includes an annular outlet positioned adjacent to a second end of the chamber farthest from the outlet end, and configured to introduce the shroud gas into the space between the internal wall of the chamber and the tubular structure of the torch. 
     
     
         4 . The apparatus of  claim 1 , wherein the nozzles are circumferentially displaced with respect to each other in the chamber internal wall. 
     
     
         5 . The apparatus of  claim 1 , wherein the nozzles are configured to inject the combustible material in a direction perpendicular to an axis of the chamber. 
     
     
         6 . The apparatus of  claim 1 , wherein the nozzles are configured to inject the combustible material at an acute angle with respect to an axis of the chamber. 
     
     
         7 . The apparatus of  claim 1 , further comprising:
 a cooling coil encircling at least a part of the chamber; and   a refractory material lining a portion of the internal wall adjacent to the outlet end of the chamber, wherein the refractory material lining is tapered such that a downstream end is smaller than an upstream end.   
     
     
         8 . The apparatus of  claim 7 , wherein the refractory material comprises a plurality of refractory liners