Simulation Experiment And Numerical Research On Deposition And Scaling On Blade Surface Inside Flue Gas Used For Fluid Catalytic Cracking Unit

Recent years,with a significant change of the Fluid Catalytic Cracking(FCC)technological conditions,scaling on the flue gas turbine blade is becoming increasingly common in the FCC energy recovery system.It is important for R&D of the scale inhibition technology to figure out the interaction mechanism between the catalyst particles and the blade.Theoretical analysis,numerical computation as well as simulation experiment were carried out in this paper in order to investigate the scaling on the balde surfaces.Firstly,we hypothesize that the catalyst particles are ideal elastic and plastic balls.With the help of elastic-plastic mechanics and the impact contact theory,a new deposition model was discussed and presented in Section 3.Secondly,with this model written into a User Defined Function(UDF)and imported into the Computational Fluid Dynamics software Fluent,the discussion of gas-solid flow field inside a two stage flue gas turbine was presented in Section 4.A simulation experiment was carried out and the scale samples similar to the actual ones was acquired due to a series of methods adopted in order to guarantee the interaction forces between the catalyst particles and the blade surfaces to be true.Based on the simulation experiment,a brief discussion of the influence of factors as Na,Ca,Fe,and S on the scaling with the multiple factor analysis method was described in Section 5.The experiment makes up for the the shortage of the computational method as the latter cannot take the chemical change of the particels into consideration.Furthermore,the influence of factors such as temperature and particle diameter on the scaling was discussed and described into equations which could provide key parameter to the theoretical analysis and the simulation.All the works done in the past three years could provide the theoretical and methodological guide to further study of the scale inhibition.The results showed that: the model established in this paper was in good consistent with the actual conditions.The first stage of the two stages plays a main role in the energy converting process.However,in the second stage stator,the foliage morphological parameter needs improvement since the old one has some flaw.The deposition curve showed a "U" style pattern,in another word,there would be more particles depositing on the leading and trailing edge,and less on the middle section.The importance of the four kinds of elements ranks in the order as iron,sulfur,sodium,calcium.What's more,there is strong interaction between sodium and sulfur,that is to say these two kinds of elements should be avoided to show up at the same time.With the temperature grows,the possibility of scale increases,and the relationship between them is described in an equation in this paper.The diameter with which the catalyst particles are inclined to scale range below 15 micrometers and from 20 micrometers to 25 micrometers as the results show.