Study On Slurrying Performance Of Coal Water Slurry From Simulated Wastewater In Lurgi Gasification

Lurgi gasification wastewater is an organic industrial wastewater with complex composition,difficult treatment and high calorific value.The pollutants are mainly ammonia,carbon dioxide,phenol,fatty acids,oil and a small amount hydrogen sulfide,etc.If it is discharged without treatment,it will easily cause water pollution and damage the ecological environment.In the past,most of the treatment methods for Lurgi gasification wastewater were costly and ineffective.Therefore,it is necessary to develop a new technology for recycling and utilization of Lurgi gasification wastewater with simple process and low cost.Coal water slurry(CWS)is a relatively mature gasification raw material and slurry fuel instead of oil.And it has the characteristics of high combustion efficiency and low pollution discharge,and it has good adaptability to pulping water.Thus,this paper uses Lurgi gasification wastewater to prepare CWS directly,that is,coal Lurgi water slurry(CLWS),which not only reduces wastewater discharge,but also saves clean water for pulping,and achieves the purpose of resource utilization of refractory organic industrial wastewater.In this paper,the slurry forming characteristics of Lurgi gasification wastewater and coal slurry are studied in the laboratory to explore the feasibility of this new type of slurry.In order to study the slurry forming characteristics of the preparation of CWS in Lurgi gasification wastewater,the parameters of CLWS prepared from Lurgi gasification wastewater and CWS from deionized water such as the apparent viscosity,concentration and shear rate were determined.And it was found that the incorporation of Lurgi gasification wastewater can increase the fixed viscosity of coal water slurry by comparing and analyzing the fixed viscosity and "viscosity-concentration" characteristic curves of the two slurries.The rheological characteristics of CLWS and CWS were compared and found that the incorporation of Lurgi gasification wastewater did not change the rheological properties of CWS,but reduced the viscosity of the slurry,which was more conducive to storage,transportation and atomization of CWS.Observing the degree of water-loss,the stability of CLWS and CWS was studied.The results show that the water-loss level of CLWS is lower,indicating that the incorporation of Lurgi gasification wastewater can improve the stability of slurry.In order to study the influence of the main components of Lurgi gasification wastewater on the slurry characteristics of CWS,different concentrations of organic waste liquid(phenol,ammonia nitrogen)were simulated,and the parameters of coal wastewater slurry(CWWS)made from waste liquid such as the apparent viscosity,concentration and shear rate were determined.It was found that phenol can increase the fixed viscosity concentration of the CWS and the ammonia nitrogen will decrease the fixed viscosity concentration of CWS by comparing and analyzing the fixed viscosity and the “viscosity-concentration” characteristic curve of the CWWS and the CWS.The rheological properties of waste water coal slurry and conventional coal water slurry were compared and found that phenol and ammonia nitrogen did not change the rheological properties of coal water slurry.Phenol can reduce the viscosity of coal water slurry and improve the fluidity of slurry.Ammonia nitrogen increases the viscosity of the coal water slurry and destroys the fluidity of the slurry.Through the study of the degree of water-loss of CWWS and CWS,it can be found that the higher the phenol concentration,the better the stability of the slurry;the ammonia nitrogen can improve the stability of the slurry.The slurry formation mechanism of CLWS was studied by determining the zeta potential of CWS and coal-water contact angle.The results of Zeta potential show that phenol has little effect on the zeta potential of the slurry,indicating that phenol has little effect on the stability of CWS;ammonia nitrogen enhances the absolute value of zeta potential of CWS,and with the increase of ammonia nitrogen concentration,the absolute value of the zeta potential of the slurry increases,indicating that ammonia nitrogen can improve the stability of the slurry.Through the determination of the contact angle,it can be found that phenol can enhance the wettability of the surface of the coal particles and reduce the viscosity of the CWS,which is beneficial to slurry formation;ammonia nitrogen can enhance the hydrophobicity of the coal particle surface and increase the viscosity of the slurry,which is not conducive to pulp.