Oxy/fuel combustion system with little or no excess oxygen

Abstract

The disclosure includes a combustion system including a primary reactor arranged and disposed to receive a solid fuel and a first oxygen stream and deliver a first substantially gaseous product and a substantially solid or molten product, a secondary reactor in fluid communication with the primary reactor, and a furnace in fluid communication with the secondary reactor.

1 . A combustion system comprising:
 a primary reactor arranged and disposed to receive a solid fuel and a first oxygen stream and deliver a first substantially gaseous product and a substantially solid or molten product;   a secondary reactor in fluid communication with the primary reactor; disposed to receive a second oxygen stream thereby converting the first substantially gaseous product from being oxygen deficient upon entering the secondary reactor to oxygen rich upon exiting the secondary reactor; and   a furnace in fluid communication with the secondary reactor.   
   
   
       2 . The system of  claim 1 , wherein at least one of the oxygen streams is substantially devoid of fluids selected from the group consisting of air, nitrogen, and combinations thereof. 
   
   
       3 . The system of  claim 1 , wherein at least one of the oxygen streams comprises at least about 30% by weight O 2 . 
   
   
       4 . The system of  claim 1 , wherein the primary reactor is configured to operate with a stoichiometric ratio of less than 1.0. 
   
   
       5 . The system of  claim 1 , wherein the secondary reactor is configured to operate with a stoichiometric ratio of greater than 1.0. 
   
   
       6 . The system of  claim 1 , wherein the combustion system is configured to measure one or more properties of the combustion gases that can be correlated with the overall stoichiometric ratio of the system. 
   
   
       7 . The system of  claim 1 , wherein the primary reactor is configured to operate with a stoichiometric ratio of less than 0.95. 
   
   
       8 . The system of  claim 1 , wherein the secondary reactor is configured to operate with a stoichiometric ratio of between 1.0 and 1.10. 
   
   
       9 . The system of  claim 1 , wherein the secondary reactor is configured to operate with a stoichiometric ratio of between 1.0 and 1.05. 
   
   
       10 . The system of  claim 1 , wherein the partially combusted gaseous product is substantially surrounded by an oxidizing gas within at least a portion of the secondary reactor. 
   
   
       11 . The system of  claim 10 , wherein the oxidizing gas includes oxygen. 
   
   
       12 . The system of  claim 10 , wherein the oxidizing gas includes recycled flue gas. 
   
   
       13 . The system of  claim 10 , wherein the oxidizing gas comprises both oxygen and recycled flue gas. 
   
   
       14 . The system of  claim 1 , wherein the second oxygen stream is mixed with the partially combusted gaseous product as it exits the secondary reactor. 
   
   
       15 . The system of  claim 1 , wherein the primary reactor is configured to permit a residual solid material in a molten state and substantially free of residual carbon to be removed from it. 
   
   
       16 . The system of  claim 1 , further comprising a recirculator arranged and disposed to permit a flue gas to be transported from a flue to the primary reactor. 
   
   
       17 . The system of  claim 1 , wherein a local combustion instrument is arranged and disposed to provide information on conditions within the secondary reactor and/or of an expellant fluid from the secondary reactor. 
   
   
       18 . The system of  claim 1 , further comprising at least one additional secondary reactor in fluid communication with the primary reactor; wherein the additional secondary reactor and the first secondary reactor are arranged and disposed to communicate at least one stream of an oxidizing gas to the first substantially gaseous product, wherein the additional secondary reactor and the first secondary reactor are in fluid communication with the furnace, wherein the primary reactor is configured to operate with a stoichiometric ratio of less than 1.0, wherein the secondary reactor is configured to operate with a stoichiometric ratio of greater than 1.0, and wherein the combustion system is configured to measure at least a property of the combustion gases that can be correlated with the overall stoichiometric ratio of the system. 
   
   
       19 . The system of  claim 1 , wherein the furnace is arranged and disposed to receive a fluid selected from the group of fluids consisting of oxygen, recycled flue gas, and combinations thereof, wherein the furnace is arranged and disposed to receive the fluid in a portion of the furnace substantially removed from the secondary reactors thereby permitting an overall stoichiometric ratio of the system greater than 1.0. 
   
   
       20 . A combustion system as in  claim 1 , further comprising:
 a local combustion instrument arranged and disposed to provide information selected from the group consisting of conditions within the secondary reactor, conditions of an expellant fluid from the secondary reactor, and combinations thereof;   a global combustion instrument arranged and disposed to provide information on conditions within the flue gas at a point downstream from the furnace; and   a controller arranged and disposed to controllably provide oxygen streams in response to the information.   
   
   
       21 . A method of operating a combustion system comprising:
 providing a primary reactor arranged and disposed to receive a solid fuel and a first oxygen stream and deliver a first substantially gaseous product and a substantially solid or molten product;   providing a secondary reactor in fluid communication with the primary reactor; disposed to receive a second oxygen stream converting the first substantially gaseous product from being oxygen deficient upon entering the secondary reactor to oxygen rich upon exiting the secondary reactor;   providing a furnace in fluid communication with the secondary reactor; and   determining a stoichiometric ratio selected from the group consisting of the stoichiometric ratio of the primary reactor, the stoichiometric ratio of the secondary reactor, the stoichiometric ratio of the furnace, and combinations thereof.   
   
   
       22 . The method of  claim 21 , further comprising:
 providing a controlled amount of oxygen to the primary reactor to maintain a stoichiometric ratio of less than about 1.0; and   providing a controlled amount of oxygen to the secondary reactor to maintain a stoichiometric ratio of greater than about 1.0.   
   
   
       23 . The method of  claim 22 , further comprising operating with the stoichiometric ratio of the primary reactor below 0.95. 
   
   
       24 . The method of  claim 22 , further comprising operating with the stoichiometric ratio of the secondary reactor between 1.0 and 1.10. 
   
   
       25 . The method of  claim 22 , further comprising operating with the stoichiometric ratio of the secondary reactor between 1.0 and 1.05.