Flameless thermal oxidation apparatus and methods

Abstract

A thermal oxidizer is provided in which off-gases in a process stream are thermally oxidized within substantially the entire interior volume of an oxidation chamber. The thermal oxidation is conducted without the presence of a flame or with only a minor portion of one or more fuels being combusted in a flame.

1 . A method for thermally oxidizing components in an oxidation chamber having an internal lining, said method comprising the steps of:
 (a) initially heating said oxidation chamber lining; and   (b) then delivering said components to said oxidation chamber under conditions to initiate thermal oxidation of said components as a result of heat transfer from said heated oxidation chamber lining.   
     
     
         2 . The method of  claim 1 , wherein said step of delivering said components to the oxidation chamber includes the step of delivering said components to said oxidation chamber in a fluid stream. 
     
     
         3 . The method of  claim 2 , including the step of flowing said fluid stream through said oxidation chamber during or following said thermal oxidation of said components. 
     
     
         4 . The method of  claim 3 , including the steps of providing one or more fuels among said components in said fluid stream and maintaining conditions within said oxidation chamber to thermally oxidize said one or more fuels in said fluid stream as a result of said heat transfer from said oxidation chamber lining while said fluid stream is passing through said oxidation chamber. 
     
     
         5 . The method of  claim 4 , wherein the step of maintaining conditions within said oxidation chamber to thermally oxidize said one or more fuels in said fluid stream comprises providing said one or more fuels in said fluid stream at local concentrations below the lower flammability limit while said fluid stream is passing through said oxidation chamber. 
     
     
         6 . The method of  claim 5 , including the step of reheating said oxidation chamber lining by changing said conditions within said oxidation chamber to cause combustion of said one or more fuels in said fluid stream. 
     
     
         7 . The method of  claim 6 , wherein said step of changing said conditions within said oxidation chamber comprises changing the local concentrations of said one or more fuels to above said lower flammability limit. 
     
     
         8 . The method of  claim 4 , wherein the step of maintaining conditions within said oxidation chamber to thermally oxidize said one or more fuels in said fluid stream comprises flowing said fluid stream through a reduced diameter passageway at a flow rate above a turbulent flame speed for said one or more fuels. 
     
     
         9 . The method of  claim 8 , including the step of reheating said oxidation chamber lining by changing said conditions within said oxidation chamber to cause combustion of said one or more fuels in said fluid stream. 
     
     
         10 . The method of  claim 9 , wherein said step of changing said conditions within said oxidation chamber comprises changing the flow rate of said fluid stream to below said turbulent flame speed for said one or more fuels. 
     
     
         11 . The method of  claim 1 , wherein said step of initially heating said oxidation chamber lining comprises delivering said components to said oxidation chamber under conditions to cause combustion of said components. 
     
     
         12 . The method of  claim 11 , wherein said step of initially heating said oxidation chamber lining comprises delivering said components to said oxidation chamber in a fluid stream. 
     
     
         13 . The method of  claim 12 , wherein said step of initially heating said oxidation chamber lining comprises the step of providing one or more fuels among said components in said fluid stream. 
     
     
         14 . The method of  claim 1 , including the steps of flowing a fluid stream containing one or more fuels through said oxidation chamber under initial conditions to cause combustion of said one or more fuels to cause said initial heating of said oxidation chamber lining, and then changing said conditions to cause said thermal oxidation of said components as a result of heat transfer from said oxidation chamber lining. 
     
     
         15 . The method of  claim 14 , wherein said step of delivering said components to said oxidation chamber comprises delivering said components comprising said one or more fuels. 
     
     
         16 . The method of  claim 15 , including further changing said conditions to cause combustion of said one or more fuels and reheating of said oxidation chamber lining. 
     
     
         17 . The method of  claim 16 , including the steps of cycling between said step of thermal oxidation of said components and said step of reheating of said oxidation chamber lining. 
     
     
         18 . The method of  claim 14 , wherein said step of changing said conditions comprises changing local concentrations of said one or more fuels from within a flammability range to outside said flammability range for said one or more fuels. 
     
     
         19 . The method of  claim 18 , including the step of increasing the mixing of said one or more fuels in said fluid stream to cause said step of changing local concentrations of said one or more fuels from within a flammability range to outside said flammability range for said one or more fuels. 
     
     
         20 . The method of  claim 14 , wherein said step of changing said conditions comprises changing the flow rate of said fluid stream from below a turbulent flame speed to above said turbulent flame speed for said one or more fuels. 
     
     
         21 . The method of  claim 4 , including the step of including volatile organic compounds, semi-volatile organic compounds, and/or hazardous air pollutants as said components in said fluid stream. 
     
     
         22 . The method of  claim 21 , including the step of adding said volatile organic compounds, semi-volatile organic compounds, and/or hazardous air pollutants to said fluid stream from a process stream. 
     
     
         23 . The method of  claim 22 , including the step of adding at least a portion of said process stream to said fluid stream at a location within said oxidation chamber. 
     
     
         24 . The method of  claim 22 , including the step of adding at least a portion of said process stream to said fluid stream prior to delivering said fluid stream to said oxidation chamber. 
     
     
         25 . The method of  claim 5 , including the step of premixing at least a portion of said one or more fuels with combustion air in said fuel stream prior to delivering said fluid stream to said oxidation chamber. 
     
     
         26 . The method of  claim 25 , including introducing another fluid stream containing one or more of said fuels to said oxidation chamber and combusting said one or more fuels in said another fluid stream in said oxidation chamber to add supplemental heat to said oxidation chamber. 
     
     
         27 . The method of  claim 1 , including the step of maintaining said thermal oxidation for a period of time greater than one hour. 
     
     
         28 . The method of  claim 4 , wherein said step of providing one or more fuels among said components in said fluid stream comprises providing a fuel selected from one or more of the group consisting of natural gas, refinery fuel gas, hydrogen, methane, ethane, propane, butane, other hydrocarbons, carbon monoxide, and blends thereof. 
     
     
         29 . The method of  claim 28 , including the step of adding one or more diluents in said fluid stream. 
     
     
         30 . The method of  claim 4 , wherein said step of providing one or more fuels among said components in said fluid stream comprises including natural gas as one of said one or more fuels. 
     
     
         31 . The method of  claim 3 , including the step of preheating at least a portion of said fluid stream before said step of flowing said fluid stream through said oxidation chamber. 
     
     
         32 . The method of  claim 4 , wherein said step of initially heating the oxidation chamber lining comprises heating the oxidation chamber lining to a temperature within the range of 1,800 to 3,000° F. 
     
     
         33 . The method of  claim 32 , wherein the step of providing one or more fuels comprises the step of including natural gas among said components in the fluid stream. 
     
     
         34 . The method of  claim 1 , wherein the step of initially heating said oxidation chamber lining comprises the steps of creating hot flue gases by burning one or more fuels in a burner which is in fluid-flow communication with said oxidation chamber, and delivering the hot flue gases into said oxidation chamber to heat said lining to a preselected temperature. 
     
     
         35 . The method of  claim 34 , including the steps of introducing said one or more fuels into an interior chamber of said burner at a first location and introducing combustion air or other oxidant into said interior chamber at a second location a preselected distance upstream from said first location during said step of initially heating said lining in the oxidation chamber. 
     
     
         36 . The method of  claim 35 , including the step of causing more complete mixing of said one or more fuels and said combustion air to cause said thermal oxidation of said components in the oxidation chamber. 
     
     
         37 . The method of  claim 2 , including the step of preventing recirculation of said fluid stream. 
     
     
         38 . A method for thermally oxidizing components of a fluid stream containing one or more fuels in an oxidation chamber having an internal refractory lining, said method comprising the steps of:
 (a) providing a fluid stream comprising thermally oxidizable components, including one or more fuels, and combustion air;   (b) heating said refractory lining in the oxidation chamber to a preselected temperature; and   (c) then passing said fluid stream through said oxidation chamber under conditions to cause thermal oxidation of said components as a result of heat transfer from said refractory lining and without recirculation of said fluid stream.   
     
     
         39 . The method of  claim 38 , including repeating steps (b) and (c) in sequence. 
     
     
         40 . The method of  claim 38 , wherein said step of providing a fluid stream comprises providing a fluid stream comprising methane and combustion air. 
     
     
         41 . The method of  claim 38 , wherein the step of heating said refractory lining in the oxidation chamber comprises the steps of creating hot flue gases by burning said one or more fuels in a burner which is in fluid-flow communication with said oxidation chamber, and delivering the hot flue gases into said oxidation chamber to heat said lining to said preselected temperature. 
     
     
         42 . The method of  claim 41 , including the steps of introducing said one or more fuels into an interior chamber of said burner at a first location and introducing combustion air into said interior chamber at a second location a preselected distance upstream from said first location during said step of heating said lining in the oxidation chamber. 
     
     
         43 . The method of  claim 42 , including the step of causing more complete mixing of said one or more fuels and said combustion air to stop said burning of said one or more fuels in said burner while allowing thermal oxidation of said one or more fuels as initiated by heat transfer from said refractory lining in the oxidation chamber. 
     
     
         44 . The method of  claim 41 , wherein said step of passing said fluid stream through said oxidation chamber under conditions to cause thermal oxidation of said components comprises the step of causing local concentrations of said one or more fuels in said fluid stream to be outside of a flammability range for said one or more fuels. 
     
     
         45 . The method of  claim 44 , including the step of reheating said refractory lining by changing said local concentrations of said one or more fuels in said fluid stream to be within said flammability range for said one or more fuels to cause burning of said one or more fuels. 
     
     
         46 . The method of  claim 41 , wherein said step of passing said fluid stream through said oxidation chamber under conditions to cause thermal oxidation of said components comprises the step of causing a flow rate of said fluid stream to be above a turbulent flame speed for said one or more fuels in said fluid stream. 
     
     
         47 . The method of  claim 46 , including the step of reheating said refractory lining by reducing said flow rate of said fluid stream below said turbulent flame speed to cause burning of said one or more fuels. 
     
     
         48 . The method of  claim 38 , including the step of removing said fluid stream from the oxidation chamber after said thermal oxidation of said components and delivering the fluid stream to downstream equipment. 
     
     
         49 . The method of  claim 48 , wherein said downstream equipment is selected from the group consisting of process heaters, boilers, reactor furnaces, air heaters, dryers, gas turbines, and heat exchangers. 
     
     
         50 . A thermal oxidizer comprising:
 an oxidation chamber comprising a shell defining an open interior volume and having an upstream end and a downstream end and a lining; and   means for heating said lining and for causing thermal oxidation of components in a fluid stream when present in said open interior volume, said thermal oxidation occurring as a result of heat transfer from said lining.   
     
     
         51 . The thermal oxidizer of  claim 50 , wherein said means comprises a burner at said upstream end of the shell for initially combusting one or more fuels in said fluid stream to cause said heating of said lining and for thermally oxidizing said one or more components. 
     
     
         52 . The method of  claim 1 , including maintaining said conditions during said thermal oxidation of said components to obtain NOx levels below 12 ppm dry and CO levels below 1 ppm dry. 
     
     
         53 . The method of  claim 1 , including maintaining said conditions during said thermal oxidation of said components to obtain NOx levels below 5 ppm dry and CO levels below 1 ppm dry. 
     
     
         54 . The method of  claim 1 , including maintaining said conditions during said thermal oxidation of said components to obtain NOx levels below 1 ppm dry and CO levels below 1 ppm dry.