Denitrator

A denitrator for removing nitrogen oxide in flue gas generated from a combustion furnace by injecting a reducing agent into the flue gas, the denitrator comprising:

• a housing disposed above the combustion furnace,
• wherein the housing comprises a discharge port for the flue gas at one end of the housing,
• wherein a cross-sectional area of flow of the flue gas gradually increases toward the discharge port,
• wherein the housing gathers and guides the flue gas to the discharge port,
• wherein the denitrator injects the reducing agent into another end of the housing, and
• wherein the housing comprises a ceiling that is inclined downward from the one end toward the another end.