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

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.

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.

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.