| Wastewater containing high-concentration phenol is produced from low-grade coal gasification or destructive distillation process,which includes phenol,cresol,dihydric phenol and other organic pollutants.Compared with diisopropyl ether(DIPE),methyl isobutyl ketone(MIBK)as the extractant has attracted more attention due to its higher distribution coefficient for polyhydric phenol and monohydric phenol,and has been successfully applied to industrial extraction and phenol removal process.In practical industrial applications,the preheating heat exchanger clogged seriously by the bonding process of paraffin and other ingredients because the melting point of the paraffin in water is between 55-60 ?.It is necessary to raise the extraction temperature from the original 45-50 ? to 60-80 ? to extend the operation cycle.In this paper,the liquid-liquid equilibrium(LLE)data of MIBK extraction phenol in the high temperature region were studied.The binary interaction parameters were obtained by the activity coefficient equations regression.The phenol removal performance and solvent recovery utility consumption were compared with MIBK as extractant at 70? and 45?,DIPE as extractant at 45?.This paper selected the reasonable extraction temperature for industrial practical applications,provided the comparison of the extraction performance and economic cost of ether and ketone extractant,and thus showed good practical value.MIBK was selected as the extractant,and we determined LLE data for the ternary systems MIBK-phenol-water,MIBK-o-,m-,or p-cresol-water,MIBK-(catechol,resorcinol,or hydroquinone)-water and quaternary system MIBK-phenol-catechol-water at 60?,70? and 80?.Hand and Othmer-Tobias equations were used to test the experimental data,which show a good linear relationship and a higher consistency with the experimental results.In this paper,the classical activity coefficient model(NRTL)and the UNIQUAC equations were used to correlate the experimental results,and the binary interaction parameters of the corresponding systems at different temperatures were obtained.The root mean square deviation(RMSD)of the calculation data and the experimental data was small,indicated that the two activity coefficient models were suitable for the study systems,and provided reliable binary interaction parameters for the extraction of phenol removal and solvent recovery process.The extraction and solvent recovery process at 70 ? were simulated and the operating parameters of extraction,solvent recovery and solvent stripping processes were determined.The energy consumption of the extraction and solvent recovery processes of MIBK as extractant at 70 ? and 45 ?,DIPE as extractant at 45 ? and R=1:8 under the same effluent quality requirements were compared by the simulation,and fond that when treating 130t·hr-1 high-concentration coal chemical phenol wastewater and the extraction grade was three,if the total phenol concentration of waste water was 300 ppm,when using MIBK as extractant,the circulating water comsumption could be reduced by 18% at 70? compared with which by 45?.The steam energy consumption 18.7% higher than MIBK as extractant at 45?,but still lower than the condition that using DIPE as extractant at 45? for 10%.Also,after fixing the phase ratio to 1:8,the steam consumption of the DIPE extraction at 45? could be reduced by 37%,contrast to the MIBK extraction at 70?.Hence,the circulating water consumption of the former will be higher to 10% than latter.However,in this design condition,the treated phenolic wastewater can just be reduced to 807 ppm,which is obviously higher than the industry recognized standard.This will increase the instability of the following biochemical treatments and biochemical cost. |
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