You are hired as a consultant to solve the following problem in a pilot-scale batch granulation process. The system under study is a 250 -litre mixer loaded with 75kg of dry powder. During normal production, the impeller speed is set to 45rpm and water is added at a rate of 0.5L/min through a nozzle that produces an average droplet size of 200m. The pilot-scale batch lasts for 30 minutes. Due to an incorrectly tuned controller an 'out of specification' product is produced. This is due to the set-point for the water flow being changed to 1.5L/min by a new employee. The average drop size in this instance is now estimated to be 300m. The powder surface velocity and spray width remain fixed at 35cm/s and 25cm respectively in both cases. (a) Determine the dimensionless spray flux for both normal operation and when the offspecification product is produced. Comment on your answer and explain why the product no longer meets specification when the water flow is changed. (b) It has been decided to scale up the granulation process to handle 500kg of dry powder per batch in an industrial mixer. The water to powder ratio and spray time will be maintained the same as for the normal operation of the pilot-scale process. If the spray width for the industrial process is 1 metre and the droplet size is 500m, determine the required velocity of the powder bed to maintain the same spray flux as for normal pilot-scale operation. What fraction of the nuclei formed will be from a single spray droplet in this case and what does this suggest about the industrial scale granulation