Study On Increasing The Recovery Of DMF In Low-concentration Waste Gas From The Dry-spinning Acrylic Fiber Unit

The Acrylic Fiber Plant of Fushun Petrochemical Corporation produces acrylic fiber utilizing dry spinning technique owned by DuPont. Poly(acrylonitrile) is produced by polymerization of acrylonitrile, the main monomer, with acrylic acid methyl ester and sodium 4-vinylbenzene sulfonate. The spinning solution is prepared using DMF as the solvent. During the consequent procedures including spinning, water flushing and drawing and drying, low-concentration exhaust gas is emitted and washed with water. The resultant DMF-containing solution is sent to the recycle equipment for reuse. Since the concentration of the exhaust gas is low, only 500 mg/m3, the mass transfer driving force for washing is weak and thus the energy consumption for recycling is rather high. The exhaust DMF gas emitted from the dryer is washed in the washing tower. The washing tower is a sieve-plate tower with low efficiency. In addition, the transport distance of exhaust DMF gas is too long and the position difference is large, resulting in high power consumption. Technical reformations are being carried out in the other dry-spun acrylic fiber plants to increase the DMF recycling efficiency and thus reduce the DMF consumption.Based on theoretical study, in our work, adsorption process using active carbon fiber as the adsorbent is applied to concentrate the exhaust DMF gas before being washed. The mass transfer efficiency is enhanced and the energy consumption is significantly reduced. The energy conservation benefit will be increased and the environmental pollution will be lowered by setting up an online continuous adsorption-desorption equipment filled with active carbon fiber, designing a high-efficiency washing tower and improving the original low-concentration DMF recycling procedure.