Study On Ammonia Recovery Process From Coal Gasification Wastewater And Liquid-liquid Equilibrium Of Phenol In Synergistic Extraction

The scale of modern coal chemical industry is expanding year by year,but there are still some restricting factors,among which water resources and water treatment problems have been the obstacles to the development of coal chemical industry.Coal chemical production consumes large amounts of fresh water and produces nearly 1 billion tons of wastewater each year.Different kinds of coal and the production process of coal chemical industry make the wastewater different,and the characteristic of high concentrated phenolic ammonia is the common fault of coal chemical industry wastewater.The existing coal chemical wastewater treatment process lacks ammonia purification,and the content of phenol in the phenol ammonia recovery section is too high,which affects the subsequent biochemical treatment.In this paper,the coal gasification wastewater from a plant in Inner Mongolia is taken as the representative,and the water quality of the wastewater is analyzed.The results of water quality show that the COD is as high as 27000 mg/L,and the concentration of total phenol is about 12000 mg/L,including 8800 mg/L of unit phenol,8200 mg/L of total ammonia,7900mg/L of free ammonia,and 8000 mg/L of hydrogen sulfide.There is a small amount of hydrogen sulfide in the ammonia after three-stage coagulation in the existing process,which makes the crude ammonia can not be used in the factory and can not achieve the purpose of recycling.And the extractant diisopropyl ether is difficult to treat.In view of the above situation,this paper analyzes the current process of ammonia removal,and uses Aspen Plus software to simulate the logistics table data to realize the potential of the factory and increase efficiency.On the basis of the research team,developed a new synergistic extraction agent is given priority to phenol extraction unit,and the key to the experimental results show that the ether glycol hydroxyl has synergistic extraction effect,and60% diisopropyl ether and 40% n-pentanol had the best effect,be able to increase the distribution coefficient of unit of phenol to 80,and the single extractant diisopropyl ether in comparison,the distribution coefficient of the 2 times as much.The unit phenol consists of phenol,p-methyl phenol and 2,4-dimethyl phenol,etc.The distribution coefficients of the unit phenol in different proportions were investigated by using synergistic extractant.On this basis,the selection of phenol unit of phenol as a representative material,determination of diisopropyl ether-n-pentanol-phenol-water liquid-liquid equilibrium,and by using UNIQUAC and NRTL activity coefficient model to simulate the experimental data,the results of regression namely relative root mean square error(RMSD)is within 2%,and the return of all the data have been respectively two sets of binary interaction parameters,provide basic data for process simulation.The recovery process of synergistic extractant was studied.Under the precondition of achieving the separation conditions,the theoretical plate number of solvent stripper and solvent recovery column,the optimal feeding position and the output of tower kettle at the top of the column were optimized.