PVA/Size Recovery Plant

Polyvinyl alcohol (PVA) desize effluent is a high COD contributor to plant’s Primary Oxygenation Treatment of Water operation, and being non-biodegradable, is a threat to the environment. When all-PVA/wax size is used in weaving, significant incentives exist to recover the synthetic polymer material from the desize wash water stream and reuse it.
A new technology that would eliminate the disadvantage of Ultra filtration (UF) PVA recovery process is Multieffect Evaporator or Mechanical vapor Recompression Evaporation (MVRE). The recovered PVA improves the yarn weave ability. Along with recovered PVA, pure hot water is recovered from the MVRE.
RAFAE Engineering MVRE is an energy efficient process which utilizes a vapor compressor which is used to increase the temperature and pressure of the vapors evaporated from the dilute desizing effluent. These vapors get heated to be condensed in the same evaporator body.
This is an alternate method to recover the size, which utilizes 20 KW/ ton water separated as compared to membrane separation process, which utilize 35KW/ ton water separated.

Advantages:

Saving of approximately 85% of the sizing agents
• Reduction of the costs of size applications by approx. 50%
• Less stoppage of weaving machines
• Therefore higher efficiency of the mill and increase of first quality production
• Reduction of dust generation in the weaving mill by approx. 45%
• No enzymatic or oxidative pretreatment for finishing
• Less demand of fresh water
• Strongly reduced generation of effluent by 50 – 60%
• Decrease of effluent charges or operation costs for waste water treatment