|Politecnico di Torino|
|Academic Year 2017/18|
Facilities for chemical and food industry
1st degree and Bachelor-level of the Bologna process in Chemical And Food Engineering - Torino
During the evolution of industrial production systems, chemical processes have gradually become more developed and more refined equipment and plants have been made by the food industry itself, which refines, transforms and combines substances that are objectively identified as chemical, even though they are of purely natural origin.
The course aims to show the students the most common equipment which, from the original logic, dictated by its use in the chemical field, has been adapted for use in the food industry. The course can therefore be seen as the presentation of equipment for chemical engineering unit operations, supplemented by classical observations on the evolutionary processes adopted in the transfer to the food industry and the description of the most widely used modern industrial plants.
A EQUIPMENT FOR THE HEAT EXCHANGE (4 credits)
1 Heat Exchangers without changes of state: chemical and food industries commonly make use of devices such as coaxial tubes and shell and tube; the food industry in particular also makes extensive use of plate fin devices, for example in the dairy sector, because of the possibility of cleaning the plates every day.
1.1 For liquids: two coaxial tubes and shell and tube
1.1.1 For liquid food: plates fin
1.2 For Gases
2 Heat exchangers with two changes of state: the saturated steam allows very hot temperatures to be reached or the equipment size to be reduced. It is frequently used as a technological fluid. Conversely, it is possible for a process fluid to be available in the vapor phase which must be condensed in- specific equipment.
2.1 Use of saturated steam as a heating medium
2.1.1. Steam generators, fire tube and water pipes. Saturated steam distribution. Traps.
3 Evaporators: many goods in chemical and food production are obtained in aqueous solutions which have to be concentrated through evaporation of the solvent; the main appliances are described
short tube, with recycling;
long tube, without recycling
3.1 Thermocompression evaporators. The produced steam, reconditioned, can be reused for the evaporation operations. Mechanical compressor and thermocompressor solutions are described.
3.2 The concentration (by evaporation). Multiple effects: having multiple devices available, and using them at decreasing pressures, it is possible to use the steam produced in the elements at higher pressure as a heating means.
3.2.1 Barometric Condensers.
B EQUIPMENT FOR HEAT EXCHANGE AND MASS TRANFER (1 credit)
1 Crystallizers: solvent evaporation can be made to reach- solute crystallization, this being a typical operation in the sugar sector.
1.1 Discontinuous Crystallizers: nucleation, homogeneous growth, secondary nucleation
1.2 Continuous Crystallizers
2 Dryers: the solid and moist product can be dried through evaporation of the water, adopting a stream of dry, warm air. This is a typical operation in the production of food products with reduced water activity and which are therefore kept for longer periods or for the production of flour, including those used in the brewing industry
2.1 The use of the psychometric chart
2.2 Batch Dryers.
2.3 Continuous dryers.
2.4 Suspension Dryers (example: production of powdered milk)
C EQUIPMENT FOR SIMULTANEOUS HEAT EXCHANGE AND MOMENTUM TRANSFER: MECHANICAL STIRRED REACTORS WITH THERMAL CONTROL DEVICES. (1.5 credits)
Like the chemical industry, the food industry also makes extensive use of mixing equipment both during product- processing (for example in the processing of olive oil), and in the preparation of the product for final consumption (eg in the preparation of sauces and products based on cocoa-chocolate spreads)
1 Apparatus for liquids
2 Apparatus for liquid / solid systems
3 Appliances with gas supply
D EQUIPMENT FOR PHYSICAL OPERATIONS. (1.5 credits)
Purely physical operations are very frequent; the course will only consider the main Equipment
1.1 Press filter (typical in the wine and beer industries)
1.2 Leaf Filters (widespread throughout the food industry)
1.3 Gaseous Filter Bags
2 Equipment for comminution: used in the past for basic chemistry operations, it is now traditionally used in the food processing of raw materials (such as in olive pressing, the grinding of roasted cocoa beans) and the refining of the finished product (eg coffee) .
3 Apparatus for the separation of two-phase systems based on the different density. Widespread in the environmental field, it is also used in the food industry, not only for water management, but also as process equipment, eg for the separation of emulsions in immiscible liquids.
The lessons will be supplemented by 2 laboratory practices of about 3 hours each.
Texts, readings, handouts and other learning resources
Teacher's lecture notes, loaded onto the portal.
D.Q. Kern: Process Heat Transfer. Ed. Mcgraw-Hill
Mc Cabe: Unit Operations of Chemical Engineering. Ed. Mcgraw-Hill
J.M.Coulson, J.F.Richardson: Chemical Engineering, vol 6. Ed. Butterworth-Heinemann.
Assessment and grading criteria
The exam is written oral. Access to the oral is allowed only after passing the written test with a score of more than or equal to 18/30.
Oral Exam: Based on 2 questions that cover the topics described in the program, in order to verify the basic knowledge of the main subjects of the course. Each question has a value of 10/30.
An additional question will be asked in the case of a lack of knowledge concerning either of the previous 2 questions. A deduction of 2 to 5 points will be made from the total sum.
Written examination: two hours without the use of notes or books. Supplementary material (charts, tables, ...) is provided if necessary. This test consists of numerical exercises similar to those performed duirng lectures, which are aimed to determine the ability to perform application calculations. The script has a maximum final value of 10/30.
The sum of the marks obtained in the questions and in the script determines the final score. In the presence of certain qualities of reasoning, and clear articulation of the problems, if the sum is equal to 30, the student will receive - laude.
Programma definitivo per l'A.A.2017/18