Exhaust gas treatment method, exhaust gas treatment device, and carbon fiber manufacturing system

Abstract

One object of the present invention is to provide an exhaust gas treatment method for treating exhaust gases discharged from a carbon fiber manufacturing steps which can suppress a cost increase due to an increase in an amount of an exhaust gas treated, the present invention provides an exhaust gas treatment method including: a first combusting step in which a carbonizing step-exhaust gas discharged from a carbonizing step in which the fibrous substance is carbonized in an inert gas atmosphere is treated; and a second combusting step in which a flameproofing step-exhaust gas discharged from a flameproofing step in which the fibrous substance is flameproofed in an air atmosphere and a first combusting step-exhaust gas discharged from the first combustion step are treated; and an air separating step in which nitrogen for producing the inert gas atmosphere in the carbonizing step, and the oxygen-enriched air used in the first combusting step are produced by separating air.

1 . An exhaust gas treatment device which is configured to treat exhaust gases discharged from steps of manufacturing carbon fiber from a fibrous substance,
 wherein the exhaust gas treatment device includes:   a first combustion furnace which is configured to combust a carbonizing step-exhaust gas discharged from a carbonizing step in which the fibrous substance is carbonized in an inert gas atmosphere; and   a second combustion furnace which is provided at a post-stage of the first combustion furnace, and configured to combust a flameproofing step-exhaust gas discharged from a flameproofing step in which the fibrous substance is flameproofed in an air atmosphere and a first combusting step-exhaust gas discharged from the first combustion furnace;   the first combustion furnace and the second combustion furnace communicate through a throttle portion;   the first combustion furnace is provided with a first burner which is configured to combust a carbonizing step-exhaust gas by a fuel and an oxygen-enriched air; and   an air separation device which is configured to produce nitrogen for producing the inert gas atmosphere in the carbonizing step and the oxygen-enriched air supplied into the first burner.   
     
     
         2 . The exhaust gas treatment device according to  claim 2 , wherein the exhaust gas treatment device further includes a second burner which is configured to supply a fuel into the second combustion furnace. 
     
     
         3 . An exhaust gas treatment method for treating exhaust gases discharged from steps of manufacturing carbon fiber from a fibrous substance,
 wherein the exhaust gas treatment method includes:   a first combusting step in which a carbonizing step-exhaust gas discharged from a carbonizing step in which the fibrous substance is carbonized in an inert gas atmosphere is treated; and   a second combusting step in which a flameproofing step-exhaust gas discharged from a flameproofing step in which the fibrous substance is flameproofed in an air atmosphere and a first combusting step-exhaust gas discharged from the first combustion step are treated;   in the first combusting step, the carbonizing step-exhaust gas is combusted at a low oxygen ratio of 0.8 or less by a fuel and an oxygen-enriched air;   in the second combusting step, the first combusting step-exhaust gas and the flameproofing step-exhaust gas are combusted by using heat of the first combusting step-exhaust gas; and   nitrogen for producing the inert gas atmosphere in the carbonizing step, and the oxygen-enriched air used in the first combusting step are produced by separating air.   
     
     
         4 . The exhaust gas treatment method according to  claim 3 , wherein the combustion of the first combusting step-exhaust gas and the flameproofing step-exhaust gas is promoted by supplying a fuel in the second combusting step. 
     
     
         5 . A carbon fiber manufacturing equipment including equipment which is configured to produce carbon fiber from a fibrous substance, and exhaust gas treatment equipment which is configured to treat exhaust gases from the equipment which is configured to produce carbon fiber from a fibrous substance,
 wherein the carbon fiber manufacturing equipment includes:   a flameproofing furnace which is configured to pre-oxidize and flameproof the fibrous substance in an air atmosphere;   a carbonizing furnace which is provided at a post-stage of the flameproofing furnace and configured to carbonize the fibrous substance after flameproofing in an inert atmosphere;   a first combustion furnace which is configured to combust a carbonizing step-exhaust gas discharged from the carbonizing furnace;   a second combustion furnace which is configured to communicate with the first combustion furnace through a throttle portion, and combust a first combusting step-exhaust gas and a flameproofing step-exhaust gas discharged from the flameproofing furnace;   a first burner which is provided in the first combustion furnace so as to combust the carbonizing step-exhaust gas by a fuel and an oxygen-enriched air; and   an air separation device which is configured to produce nitrogen for producing the inert gas atmosphere in the carbonizing furnace and the oxygen-enriched air supplied into the first burner from air.   
     
     
         6 . A carbon fiber manufacturing system including a step in which carbon fiber is produced from a fibrous substance and a step in which exhaust gases discharged from the step in which carbon fiber is produced from a fibrous substance are treated,
 wherein the carbon fiber manufacturing system includes:   a flameproofing step in which the fibrous substance is pre-oxidized and flameproofed at 200° C. to 300° C. in an air atmosphere;   a carbonizing step in which the fibrous substance after the flameproofing step is carbonized at 300° C. to 2,000° C. in an inert gas atmosphere;   a first combusting step in which a carbonizing step-exhaust gas discharged from the carbonizing step is combusted at a low oxygen ratio of 0.8 or less by a fuel and an oxygen-enriched air;   a second combusting step in which a first combusting step-exhaust gas discharged from the first combusting step and a flameproofing step-exhaust gas discharged from the flameproofing step are combusted using heat of the first combusting step-exhaust gas; and   an air separating step in which nitrogen for producing the inert gas atmosphere in the carbonizing step, and the oxygen-enriched air used in the first combusting step are produced by separating air.