Regeneration Method And Process Design Of Waste Activated Carbon Of Glycine Production

Natural gas method is also known as hydrocyanic acid method, which is one of the glycine production technical routes attracting most attention at home and abroad currently. This glycine production method has the feature of low cost and high quality, with a purity quotient generally up to 99%.In the production by natural gas method, to obtain the refined aminoacetic acid, it generally applies active carbon for adsorption bleaching in technique. But the spent carbon after bleaching is generally discarded or burnt without reuse, and it not only pollutes environment but also wastes resources, meanwhile, it causes a further increase of the production costs of glycine. So it needs to recycle the spent carbon produced after glycine bleaching, which can not only recover the glycine products attached on the spent carbon, but also improve the production efficiency of the enterprise, and also achieve the recycling of resources to reduce environment pollution.By analyzing the colored group substances absorbed by the spent carbon, this thesis indicated that: dilute sulphuric acid was added in the reaction process of HCN and HCHO to synthesize glycolic cyanide, and ferrous iron was inducted in the stainless steel reactor, so the excessive HCN compounded with the iron ion and formed the ferrocyanide complex ion [Fe(CN)₆]^4- , which could produce ion [Fe(CN)6]3- after oxidation. [Fe(CN)6]3- then compounded with elements like Fe,Cr,Ni,Mo of the stainless steel and produced brown-black substance. So the main materials absorbed by active carbon are ferrocyanide and ferricyanate.The thesis discussed the various regeneration methods of spent active carbon and the influencing factors. In thermal regeneration, it inspected the effects of temperature and regeneration time on it , figuring out the optimum condition of thermal regeneration is: temperature at 600℃and time in 180min; in solvent regeneration, it discussed the mass fraction of acid, the proportion to active carbon and the effect of other regeneration conditions, getting the result that the optimum condition of solvent regeneration is: the mass fraction of sulphuric acid at 70%, intimate mixing with spent active carbon with a mass ratio greater than 1.5:1, while the optimum condition in autoclave is: temperature at 600℃and pressure at 0.6181MPa, with a 4 hour reaction in it; in microwave regeneration, it inspected the time of microwave irradiation and the effects of power and loading on regeneration, which showed that the optimum condition of microwave regeneration is: ZnCl₂ ( in the concentration of 3 mol/L) mixes with active carbon(5g) with 7min's irradiation in the microwave field, which shall yield the best result.By comparison of the regeneration effects of the three methods, active carbon has the highest regeneration rate in the condition of acid regeneration, with its absorption performance 94.15% of that of the fresh active carbon, and it can be regenerated for many times with a good effect. The absorption performance after three times'regeneration can still reach up to 80% of that of the fresh active carbon.Based on the experimental data of acid regeneration, the thesis made a preliminary technical design of the regeneration of 15ton's spent active carbon per day.