[500675] Page 3 of 5 [Continues…] Particle Technology (50 Marks) Answer all questions. Please note that full marks will only be awarded when answers show the detailed supporting calculations and...

3 questions of seperation process and 3 questions of particle technology


[500675] Page 3 of 5 [Continues…] Particle Technology (50 Marks) Answer all questions. Please note that full marks will only be awarded when answers show the detailed supporting calculations and assumptions (if any) Question 1 You are dealing with the storage of biomass powder in a storage hopper of conical bottom (silo). You are the responsible engineer for the efficient and continuous discharge of the biomass powder on a conveying belt which leads the solid particles to the combustion unit of a power station feeding with biomass. a) Describe the common problem that may occur during discharging of biomass powder from storage hoppers of conical bottoms (silos), and in particular the phenomenon of caking. [3 marks] b) Draw a schematic diagram that represents the caking phenomenon. [3 marks] c) Which kind of solid fuels and under which weather conditions as most susceptible to flushing? [2 marks] d) State two other examples of any other solid particles susceptible to flushing during their discharging from their storage silos. [2 marks] [500675_Main Exam] Page 4 of 5 [Continues…] Question 2 A lab-scale leaf filter has a leaf area of 0.1 m2 and when operated at a constant pressure drop conditions of 400000 Pa produced the experimental results depicted in Figure 2, below: Figure 2 Experimental results of a leaf-filter operation with leaf area of 0.1 m2 and constant operating pressure of 400000 Pa. Calculate the: a) Time (in min) required to collect 5 m3 of filtrate during filtration of the same slurry at operating conditions of constant pressure drop of 400 kPa [7 marks] b) The time (in min) required the same amount of filtrate but in a new scaled up leaf filter press with a leaf area of 0.3 m2 and the same constant pressure conditions as above. [5 marks] c) Calculate the percentage of change in the time of filtration of the slurry when there is a change of the filter leaf area from 0.1 m2 to 0.3 m2. [5 marks] [500675] Page 5 of 5 [END] Question 3 You are a R&D engineer which has just designed a crystallizer and produced the first batch of crystals. By optical characterization of a sample, by using microscopy, you found out that the crystals are of cube shape with edge length of 3 μm. a) Discuss briefly what the equivalent circle diameter (dα) of a solid particle is. [2 marks] b) Calculate the Heywood’s volumetric shape factor (k) of this particle. [9 marks] c) In which type of applications of Chemical Engineering practise this factor finds applicability? [2 marks] d) Briefly state why it is important to estimate the sphericity (ψ) of a solid particle. [2 marks] e) Calculate the sphericity (ψ) for the solid particle mentioned above. [8 marks]