A new recovery technology is developed to recycle

N

N

-dimethyl formamide(DMF)in waste gas from wet type polyurethane synthetic leather industry.Given that the concentration of DMF in waste gas was as low as 325.6-688.3 mg·m

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it was necessary to make sure two phases contact adequately and strengthen the mass transfer by increasing contact area and enhancing the turbulence.Therefore

two-stage countercurrent absorption and two-stage fog removing system were introduced into the technology.The top section of the absorption column was filled with structured wire-ripple stainless steel packing BX500

while the lower section with sting-ripple packing CB250Y.Total height of packing material was 6 m.In addition

there were both two-stage fog removing layer and high efficiency liquid distributor at the column top.All the operating parameters

including temperature

pressure

flow rate and liquid position

could be controlled by computers without manual operation

making sure the outlet gas achieved the national emission standard that the DMF concentration should be below 40 mg·m

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.The whole equipment could recover 237.6 t of DMF each year

with the profit up to CNY 521×10

3

.