Recycling lye extracted from cellulose@ mfg. plant - has recycling system incorporated to separate valuable material from lye for re-use in plant

摘要

A process to recycle the lye extracted from a cellulose mfg. plant. There are several stages of recycling and distn. of the volatile fluid, using equipment which is integrated in the plant. ADVANTAGE - There is a saving of energy for the process as the products are re-usable. The cellulose is made from wood chippings, having an initial process with alcohol, methanol or similar fluid with a low b.pt., heated with water for a specified time. Then follows a caustic soda treatment, on similar lines, and as the cellulose prod. is washed, the weak lye is extracted and passed to the expansion chambers to reduce the temp. and pressure. A pre-heater takes treated lye back to the condenser with steam to concentrate the fluid to a high viscosity, with a percentage of lignin. This extract is then burned in the process boilers. Concd. lye is also re-used. Vapour from the unit is combined with that extracted from the expansion chambers and passed into the vaporiser, which again separate the volatile material with a lower b.pt. Condensate is also extracted at this stage. Clean water, steam and vapour condensate are then passed along the system. The vaporisers have separate heating arrangement, with either plates or tubes in each stage. A regenerative system and a columnar unit allow further sepn. and distn. when gas is cooled and extracted to be burned in the boilers. Pure methanol for re-use is also produced. Condensate and water used in the washing process of the cellulose is extracted at the points indicated