Study On The Flocculation Process And Fractal Characters Of Floc In The Water System Of Entrained-flow Coal Gasification

The simulated blackwater samples of kaolin suspension and fine slag of coal gasification are used in the paper. With the CPAM flocculant, the condition of the optimum CPAM addition, temperature and pH are tested. The fractal theory is introduced to analyze the floes images of flocculation process.The results of experiment show that the average diameter of kaolin suspension floe gets the maximum when the CPAM addition is 6 ppm and the environment temperature is 60 ℃, which is a good flocculation. When the CPAM addition is 6 ppm, the temperature reaches 50℃ and the pH is 5, the average chord length of fine flag floc black water of coal gasification is quite big, which shows a good flocculation. Acidic environment helps to make CPAM play its flocculation effect.No matter to the kaolin suspension or the water sample of fine slag, the fractal dimension has positive relation to the turbidity of the supernatant by changing the CPAM addition, temperature and pH, that is, the fractal dimension of floc enlarges and turbidity of the supernatant drop with the increase of CPAM addition, temperature and the decrease of pH. However, after reaching the peak, as CPAM addition, environment temperature and pH value continue to increase, the fractal dimension tends to decrease, the structure of floc becomes loose and the turbidity of water system increase. Thus, the fractal dimension of the flocculant has better representation in reflecting the flocculation effect.Through experiment and derivation, the relation between fractal dimension and floe settling velocity and structure is eatablished in the paper. So we can have a direct judgment of settling performance by floc fractal dimension. It can be compared with the fractal dimension of the fractal to judge settleability of the floc.