Combustion Method and System

Abstract

A method of combustion for pulverized hydro-carbonaceous fuel includes the steps of injecting an oxidant/fuel stream into a burner, causing a low-pressure zone; directing a flow of a high-temperature combustion gas from a combustion chamber into the low-pressure zone in the burner; mixing the high-temperature combustion gas with the injected oxidant/fuel stream to heat the injected oxidant/fuel stream, and injecting the heated oxidant/fuel stream from the burner to the combustion chamber, wherein the oxidant/fuel stream is rapidly devolatilized and combusted in a flame that has a high temperature; sensing a combustion parameter; and based on the sensed combustion parameter, controlling combustion to achieve at least one of a desired NOx reduction and a desired distance from the burner to a flame front.

1 - 49 . (canceled) 
   
   
       50 . A method of combustion for pulverized hydrocarbonaceous fuel, the method comprising:
 injecting an oxidant/fuel stream into a burner, causing a low-pressure zone;   directing a flow of a high-temperature combustion gas from a combustion chamber into the low-pressure zone in the burner;   mixing the high-temperature combustion gas with the injected oxidant/fuel stream to heat the injected oxidant/fuel stream, and injecting the heated oxidant/fuel stream from the burner to the combustion chamber, wherein the oxidant/fuel stream is rapidly devolatilized and combusted in a flame that has a high temperature;   sensing a combustion parameter; and   based on the sensed combustion parameter, controlling combustion to achieve at least one of a desired NOx reduction and a desired distance from the burner to a flame front.   
   
   
       51 . A method according to  claim 50 , wherein the step of controlling the combustion includes controlling the pressure of the low-pressure zone. 
   
   
       52 . A method according to  claim 51 , therein the step of controlling the pressure of the low-pressure zone includes controlling a tertiary gas fed into the low pressure zone to control the pressure of the low-pressure zone. 
   
   
       53 . A method according to  claim 52 , wherein a feeding pipe for feeding the tertiary gas is located in the first two-third of the burner measured from its entrance for the oxidant/fuel stream. 
   
   
       54 . A method according to  claim 50 , wherein the step of controlling the combustion includes controlling the flow rate of the high-temperature combustion gas from the combustion chamber into the low-pressure zone in the burner. 
   
   
       55 . A method according to  claim 50 , wherein the step of controlling the combustion includes controlling at least one of the flow rate and oxidant/fuel ratio of the injected oxidant/fuel stream. 
   
   
       56 . A method according to  claim 50 , wherein the oxidant/fuel stream is a concentrated oxidant/fuel stream. 
   
   
       57 . A method according to  claim 56 , wherein the concentrated stream has a weight ratio of oxidant to fuel in the range of 0.08 to 2.2. 
   
   
       58 . A method according to  claim 56 , wherein the concentrated stream is heated to a temperature of 700° C. to 1200° C. in a distance between 250 mm and 1950 mm as measured from the entrance of the burner for the high-temperature gas. 
   
   
       59 . A method according to  claim 56 , wherein the concentrated stream has a weight ratio of oxidant to fuel in the range of 0.7 to 1.8. 
   
   
       60 . A method according to  claim 56 , wherein the concentrated stream is injected into the burner at a speed from 10 to 60 m/s. 
   
   
       61 . A method according to  claim 56 , wherein the concentrated stream is injected into the burner at a speed from 15 to 50 m/s. 
   
   
       62 . A method according to  claim 50 , wherein a cross-sectional area of the injected oxidant/fuel stream at the entrance to the burner is a fraction of a cross-sectional area of the burner. 
   
   
       63 . A method according to  claim 62 , wherein the cross-sectional area of the injected oxidant/fuel stream at the entrance to the burner is less than 50% of the cross-sectional area of the burner. 
   
   
       64 . A method according to  claim 50 , wherein the fuel is at least one of coal and petroleum coke. 
   
   
       65 . A method according to  claim 56 , further comprising separating a primary oxidant/fuel stream into the concentrated oxidant/fuel stream and a diluted oxidant/fuel stream, and feeding the diluted stream into the combustion chamber. 
   
   
       66 . A method according to  claim 65 , wherein the step of controlling the combustion includes controlling the feeding of the diluted stream into the combustion chamber. 
   
   
       67 . A method according to  claim 65 , wherein the separating of the primary oxidant/fuel stream into the concentrated stream and the diluted stream is performed by a bent pipe. 
   
   
       68 . A method according to  claim 67 , wherein the winding angle of the bent pipe is between 60° and 120°. 
   
   
       69 . A method according to  claim 65 , wherein the primary stream contains 10% to 35% of stoichiometric oxygen. 
   
   
       70 . A method according to  claim 50 , wherein the combustion parameter includes at least one of a pressure sensor, a temperature sensor, and a chemical sensor for sensing the content of a gas. 
   
   
       71 . A method according to  claim 50 , wherein the sensing step is performed by a sensor that is placed in the burner or combustion chamber or embedded in a wall of the burner or combustion chamber. 
   
   
       72 . A method according to  claim 50 , further comprising injecting at least one additional oxidant and fuel stream. 
   
   
       73 . A method according to  claim 72 , further comprising heating one of the at least one additional oxidant and fuel stream by an additional reflow of a high-temperature combustion gas from the combustion chamber. 
   
   
       74 . A method according to  claim 72 , wherein one of the at least one additional oxidant and fuel stream is an over-fire oxidant, wherein the over-fire oxidant is 0 to 30% of the total oxidant fed to the combustion chamber. 
   
   
       75 . A method according to  claim 74 , wherein the step of controlling the combustion includes controlling the feeding of the over-fire oxidant. 
   
   
       76 . A method according to  claim 72 , wherein one of the at least one additional oxidant and fuel stream is a secondary diluted oxidant and fuel stream. 
   
   
       77 . A method according to  claim 76 , further comprising feeding the secondary stream to the combustion chamber adjacent to the periphery of the exit of the burner for the first oxidant/fuel stream. 
   
   
       78 . A method according to  claim 76 , wherein the step of controlling the combustion includes controlling the feeding of the secondary stream. 
   
   
       79 . A method according to  claim 76 , wherein the secondary stream is one of a straight flow or a swirling flow. 
   
   
       80 . A method according to  claim 79 , further comprising dividing the swirling secondary stream into an inner secondary stream and an outer secondary stream. 
   
   
       81 . A method according to  claim 80 , wherein the swirling strength is between 0.1 and 2.0. 
   
   
       82 . A method according to  claim 72 , wherein the first oxidant/fuel stream is a first concentrated oxidant/fuel stream, and wherein one of the at least one additional oxidant and fuel stream is a second concentrated oxidant and fuel stream. 
   
   
       83 . A method according to  claim 82 , wherein the second concentrated oxidant/fuel stream is heated. 
   
   
       84 . A method according to  claim 50 , wherein the step of controlling combustion includes controlling combustion to maximize NOx reduction without impermissible slagging. 
   
   
       85 . A combustion system for pulverized hydrocarbonaceous fuel, the device comprising:
 a burner that is designed to receive an oxidant/fuel stream;   a combustion chamber that is connected to the burner to send to the burner a flow of a high-temperature combustion gas to heat the oxidant/fuel stream, and to receive the heated oxidant/fuel stream from the burner for combustion;   a sensor for sensing a combustion parameter; and   a controller for controlling combustion based on the sensed combustion parameter to achieve at least one of a desired NOx reduction and a desired distance from the burner to a flame front.   
   
   
       86 . A system according to  claim 85 , wherein the controller controls the pressure of the low-pressure zone. 
   
   
       87 . A system according to  claim 86 , therein the controller controls a tertiary gas fed into the low pressure zone to control the pressure of the low-pressure zone. 
   
   
       88 . A system according to  claim 85 , wherein the controller controls the flow rate of the high-temperature combustion gas from the combustion chamber into the low-pressure zone in the burner. 
   
   
       89 . A system according to  claim 85 , wherein the controller controls at least one of the flow rate and oxidant/fuel ratio of the injected oxidant/fuel stream. 
   
   
       90 . A system according to  claim 85 , wherein the oxidant/fuel stream is a concentrated oxidant/fuel stream. 
   
   
       91 . A system according to  claim 85 , wherein the combustion parameter includes at least one of a pressure sensor, a temperature sensor, and a chemical sensor for sensing the content of a gas. 
   
   
       92 . A system according to  claim 85 , wherein at least one additional oxidant and fuel stream is injected into the combustion chamber. 
   
   
       93 . A system according to  claim 87 , wherein the tertiary gas is any gas including atmosphere air, oxygen, hydrogen, nitrogen, carbon dioxide, carbon monoxide, ammonium, noble gases, steam, methane, ethane, ethylene, or any combinations of those gases. 
   
   
       94 . A system according to  claim 92 , wherein one of the at least one additional oxidant and fuel stream is heated by an additional reflow of a high-temperature combustion gas from the combustion chamber. 
   
   
       95 . A system according to  claim 92 , wherein one of the at least one additional oxidant and fuel stream is a secondary diluted oxidant and fuel stream. 
   
   
       96 . A system according to  claim 92 , wherein the first oxidant/fuel stream is a first concentrated oxidant/fuel stream, and wherein one of the at least one additional oxidant and fuel stream is a second concentrated oxidant and fuel stream. 
   
   
       97 . A system according to  claim 96 , wherein the second concentrated oxidant/fuel stream is heated using reflow gas from the combustion chamber 
   
   
       98 . A system according to  claim 85 , wherein the controller controls combustion to maximize NOx reduction without impermissible slagging.