PURPOSE: To clean air efficiently by a method wherein NOx is removed from polluted air by adsorption, the NOx is desorbed to obtain a concentrated desorbed gas, and the desorbed gas is contact-decomposed to convert the gas into a gas not causing environmental pollution.
CONSTITUTION: Air 1 is led to a dust removing apparatus 3 by a blower 2 and after dust and soot are removed, a gas 5 discharged from a NOx concentrating tower 15 is added to the resulting air to give a NOx adsorbing tower inlet gas 4, and it is supplied to a NOx adsorbing tower 17. In a NOx desorbing tower 18, previously adsorbed NOx is desorbed in a gas side. The desorbed NOx gas 7 is mixed with a recycle gas 16 from a NOx decomposition process and supplied to a NOx concentrating tower 19. In the NOx concentrating tower 19, almost all NOx is adsorbed and removed and almost all gas of nitrogen and oxygen passes through and is returned to the NOx adsorbing tower 17 as a recycle gas 5. As a result, necessary amount of a catalyst for contact decomposition of NOx may be small.
IIDA KOZO
NOJIMA SHIGERU
IZUMI JUN
MURAKAMI NOBUAKI
