Oxycombustion Circulating Fluidized Bed Reactor and Method of Operating Such a Reactor

Abstract

An oxycombustion circulating fluidized bed reactor includes a reactor chamber and a gas distribution arrangement provided in a bottom section of the reactor chamber for introducing gas into the reactor chamber. The gas distributor arrangement includes a first gas feeding system and a second gas feeding system for introducing oxygen-rich gas into the reactor chamber. The first gas feeding system includes a first wind box and the second gas feeding system includes a second wind box. The first wind box has a common wall with the reactor chamber and the second wind box is arranged under the first wind box and has a common wall with the first wind box.

1 . An oxycombustion circulating fluidized bed reactor comprising:
 a reactor chamber; and   a gas distribution arrangement provided in a bottom section of the reactor chamber for introducing gas into the reactor chamber, the gas distributor arrangement comprising a first gas feeding system and a second gas feeding system for introducing oxygen-rich gas into the reactor chamber, wherein (i) the first gas feeding system comprises a first wind box and the second gas feeding system comprises a second wind box and (ii) the first wind box has a common wall with the reactor chamber and the second wind box is arranged under the first wind box and has a common wall with the first wind box.   
     
     
         2 . An oxycombustion circulating fluidized bed reactor according to  claim 1 , wherein the surfaces of the second wind box are made of a fireproof material in the circumstances of elevated oxygen content gas, prevailing in the second wind box. 
     
     
         3 . An oxycombustion circulating fluidized bed reactor according to  claim 1 , wherein the second wind box has its inner walls lined with a refractory material. 
     
     
         4 . An oxycombustion circulating fluidized bed reactor according to  claim 1 , wherein the second wind box is in connection with the reactor chamber via a plurality of conduits extending from the second wind box through the first wind box into the reactor chamber. 
     
     
         5 . An oxycombustion circulating fluidized bed reactor according to  claim 4 , wherein the conduits are removably arranged. 
     
     
         6 . An oxycombustion circulating fluidized bed reactor according to  claim 1 , wherein the reactor chamber is provided with a particle separator for separating fluidized particles which are entrained with the gases resulting from reactions taking place in the reaction chamber, the particle separator is provided with a gas outlet and an outlet for separated particles, and the gas outlet is arranged in flow communication with the first wind box and the second wind box via a recycling conduit. 
     
     
         7 . An oxycombustion circulating fluidized bed reactor according to  claim 6 , wherein the recycling conduit is in connection with a first mixing element in the first gas feeding system through a conduit provided with a first flow control device and with a second mixing element in the second gas feeding system through a conduit provided with a second flow control device. 
     
     
         8 . An oxycombustion circulating fluidized bed reactor according to  claim 7 , wherein the gas distribution arrangement is in connection with a source of oxygen-rich gas. 
     
     
         9 . An oxycombustion circulating fluidized bed rector according to  claim 8 , wherein the source of oxygen-rich gas is in connection with the first mixing element through a conduit provided with a third control device and with a second mixing element through a conduit provided with a fourth control device. 
     
     
         10 . A method of operating an oxycombustion circulating fluidized bed reactor that includes a reactor chamber and a gas distribution arrangement provided in a bottom section of the reactor chamber, the method comprising:
 introducing gas into the reactor chamber through the gas distribution arrangement, the gas distributor arrangement comprising a first gas feeding system and a second gas feeding system through which gas is introduced into the reactor chamber; and   introducing oxygen-rich gas into the reactor chamber through a first wind box of the first gas feeding system, and through a second wind box of the second gas feeding system such that the oxygen-rich gas introduced through the second wind box is introduced through a plurality of conduits extending through the first wind box into the reactor chamber.   
     
     
         11 . A method of operating an oxycombustion circulating fluidized bed reactor according to  claim 10 , wherein the gas introduced into the reactor chamber contains recycled gas, which recycled gas is divided into streams comprising a stream that is controllably introduced into the first gas feeding system and a stream that is controllably introduced into the second gas feeding system, the method further comprising:
 introducing oxygen-rich gas into the stream of recycled gas in the first gas feeding system so that the oxygen content of the gas in the first gas feeding system is, at most, a first oxygen content, and that oxygen-rich gas is introduced into the stream of recycled gas in the second gas feeding system so that the oxygen content of the gas in the second gas feeding system is at least the first oxygen content.   
     
     
         12 . A method of operating an oxycombustion circulating fluidized bed reactor according to  claim 10 , wherein the first oxygen content is more than twenty-three volume percent. 
     
     
         13 . A method of operating an oxycombustion circulating fluidized bed reactor according to  claim 10 , wherein the oxygen content of the gas in the first gas feeding system is less than the oxygen content of the gas in the second gas feeding system. 
     
     
         14 . A method of operating an oxycombustion circulating fluidized bed reactor according to  claim 10 , wherein the oxygen-rich gas in the second gas feeding system is fed to the second wind box and is subjected to heat flow from the reactor chamber, which heat flow is decreased by heating the gas in the first wind box. 
     
     
         15 . A method of operating an oxycombustion circulating fluidized bed reactor according to  claim 10 , wherein the oxygen-rich gas in the second wind box is introduced through a plurality of pipes extending through the first wind box into the reactor chamber and is simultaneously heated by the gas in the first wind box. 
     
     
         16 . A method of operating an oxycombustion circulating fluidized bed reactor according to  claim 10 , wherein the temperature of the oxygen-rich gas in the second wind box is maintained to be lower than the temperature of gas in the first wind box. 
     
     
         17 . A method of operating an oxycombustion circulating fluidized bed reactor according to  claim 10 , further comprising adjusting the first oxygen to minimize a risk of self ignition of any combustible material present in the gas distribution arrangement.