Patent ID: 8221634
Filing Date: 2012-07-17
Classification: B01D,C07C,Y10S

Abstract:
1. A process for separating and recovering waste alkali from a cyclohexane oxidation solution, comprising the following steps: (a) a first separation step that comprises sedimentating by gravity a cyclohexane oxidation solution that contains a solution of sodium hydroxide, giving a mixture of the first separation step that includes a cyclohexane oxidation solution removed of over 99% alkali liquor; (b) a second separation step that comprises washing the mixture of the first separation step with water, so that the alkaline species in the feedstock migrate to water and the alkaline species in water are enriched, wherein the resulting mixture of the mixture of the first separation step and water which are mixed thoroughly is subjected to gravity sedimentation to obtain a mixture of the second separation step that includes a cyclohexane oxidation solution further removed of 95%-99% alkali liquor; (c) a third separation step that comprises washing the mixture of the second separation step with water, wherein the resulting mixture of the mixture of the second separation step and water which are mixed thoroughly is subjected to gravity sedimentation to obtain a mixture of the third separation step that includes a cyclohexane oxidation solution further removed of 95%-99% alkali liquor; (d) a fourth separation step that comprises vortex-separating the mixture of the third separation step at a temperature in the range of 50-200° C. and a pressure drop in the range of 0.1-0.25 MPa to further remove alkali liquor comprising alkaline species, giving a mixture of the fourth separation step that includes a cyclohexane oxidation solution further removed of 85%-98% alkali liquor; (e) coalescence-separating the mixture of the fourth separation step at a temperature in the range of 50-200° C. and a pressure drop in the range of 0.05-0.15 MPa to further remove alkali liquor comprising alkaline species, giving a cyclohexane oxidation solution comprising less than 3 mg/L Na (f) recycling 80%-90% of the alkali liquor removed by the steps (a), (b), (c), (d) and (e) to be mixed with the cyclohexane oxidation solution in the step (a) with the remaining 10%-20% expelled; (g) subjecting the remaining 10%-20% of the alkali liquor expelled to incineration in an incinerator to obtain a molten effluent including sodium carbonate, the molten effluent flowing out from the bottom of an incinerator chamber; (h) setting a guide bucket underneath an outlet of the incinerator chamber for the molten effluent to flow out, wherein a saturated solution of sodium carbonate is spurting in the guide bucket, and the molten effluent is crushed by a gas-water mixture from a spurting nozzle before the molten effluent drops into the guide bucket to form a saturated effluent solution; and (i) subjecting the saturated effluent solution comprising solids to a solid-liquid separation, after which solid particles are dried and packaged, while the remaining saturated effluent solution is pressurized and then recycled into the guide bucket.