Multi-stage decorative burner

Abstract

The invention provides systems and methods for multi-stage burners. The burner may accept a variable input fuel stream, which may be divided into a plurality of output fuel streams. The fuel stream may be divided by a pressure-actuated flow separator that may distribute an increasing amount of fuel to a secondary flow stream as the input flow rate of the input fuel stream increases. One or more of the output streams may be conditioned to provide a desired flame characteristic. The multi-stage burners may be decorative burners, and may be used for theatrical displays or other fire displays.

1 . A multi-stage burner with variable output, comprising:
 a fuel input stream;   a proportioning system that divides the fuel input stream into multiple fuel output streams;   a passage that introduces air into at least one of the fuel output streams; and   an outlet that combines the fuel output streams in a common atmospheric combustion zone.   
     
     
         2 . The burner of  claim 1  wherein the proportioning system changes the relative proportions of fuel flowing in the fuel output streams with respect to the total fuel flowing through the burner. 
     
     
         3 . The burner of  claim 2  wherein the fuel output streams include a primary fuel output stream and a secondary fuel output stream, and the proportioning system diverts an increasing proportion of the total fuel to the secondary with increasing total fuel flow. 
     
     
         4 . The burner of  claim 3  wherein the proportioning system comprises a spring-loaded relief that blocks fuel from flowing to the secondary fuel output stream until a threshold upstream pressure is exceed, thereby causing the relief to open, permitting fuel to enter the secondary stream. 
     
     
         5 . The burner of  claim 3  wherein the proportioning system comprises
 a spring-loaded relief movable between (a) a closed position that blocks most fuel from flowing to the secondary fuel output stream, and (b) an open position that permits an increased amount of fuel to flow to the secondary fuel output stream, and 
 a channel that circumvents the relief to allow fuel to flow to the secondary fuel output stream when the relief is in the closed position. 
 
     
     
         6 . The burner of  claim 3  further comprising an inspirator that is configured to draw air into the primary fuel output stream through an air passage. 
     
     
         7 . The burner of  claim 3  wherein the outlet is configured such that the primary fuel output stream exits through a smaller cylindrical tube that is co-axial with a larger cylindrical tube that conveys the secondary fuel output stream. 
     
     
         8 . The burner of  claim 7  wherein the smaller cylindrical tube extends past the plane of the larger cylindrical tube. 
     
     
         9 . The burner of  claim 3  further comprising a third pilot stream that is used to ignite the flame fed by the primary and secondary fuel output streams. 
     
     
         10 . The burner of  claim 3  further comprising a diffuser in the secondary fuel output stream to uniformly slow the fluid flow. 
     
     
         11 . The burner of  claim 3  further comprising a laminizer configured to divide the secondary fluid output stream into a series of smaller channels. 
     
     
         12 . The burner of  claim 3  wherein the secondary fuel output stream has a larger cross-sectional area at its outlet than the primary fuel output stream at its outlet. 
     
     
         13 . A method for producing a flame comprising the following steps:
 controlling an input flow rate of a fuel input stream;   separating the flammable gas input stream into multiple output streams, wherein a first output stream carries the majority of the fuel output flow for a first range of input flow rates and a second output stream carries the majority of the fuel output flow for a second range of input flow rates;   conditioning at least one output stream to obtain desired flame properties at different input flow rates; and   introducing the first and second output streams into a common atmospheric combustion region.   
     
     
         14 . The method of  claim 13  wherein the conditioning of the at least one output stream includes using a diffuser to uniformly slow the fluid flow. 
     
     
         15 . The method of  claim 13  wherein the conditioning of the at least one output stream includes using one or more laminizer to divide the at least one output stream into a series of smaller channels. 
     
     
         16 . The method of  claim 13  wherein said separating is performed by a spring-loaded relief that is in a first position for the first range of input flow rates and in a second position for the second range of input flow rates. 
     
     
         17 . A method for producing a flame comprising the following steps:
 controlling the flow rate of a flammable gas input stream;   diverting some of the flammable gas input stream through an orifice to a primary output stream;   sending remaining flammable gas from the flammable gas input stream to a secondary output stream via a relief valve that opens when the pressure upstream of the relief valve is above a specific design pressure; and   introducing both streams into a common atmospheric combustion region.   
     
     
         18 . The method of  claim 17  further comprising entraining air into the primary output stream using an inspirator. 
     
     
         19 . The method of  claim 17  further comprising conditioning the secondary output stream to be a substantially uniform, laminar flow. 
     
     
         20 . The method of  claim 17  wherein the secondary output stream surrounds the primary output stream.