Abstract
This thesis work is devoted to the study of a machinery for the sterilization and cooling of the tomato, the simulation, the analysis of the process variables and the determination of the control parameters. The entire system is designed and built by the company CFT SpA in which the undersigned has done an internship.
The system called SFC Flash cooler is used to sterilize aseptic large flow of products. The incoming product sterilized at 105 ° C with direct steam injection and flash cooled instantaneously to heat the vacuum chamber. The evaporation for flash causes the cooling of the product up to an equilibrium temperature of about 35 ÷ 38 ° C (application aseptic).
In the first part of the thesis has been reproduced process in the totality of its parts using the software Simulink, more precisely through the blocks library containing the mass and energy balances equations in the various sections. Assign working conditions, introduced several simplifying assumptions and set the various combinations of process variables it was possible to start the simulations.
The whole simulated system was compared with real data taken in the field during the traveling for the launch of the machinery in company Tomate del Sur, Seville. The accuracy of the system was checked and was possible to implement PID feedback on different parts of the machine to determine the best control system.
The simulator has offered the opportunity to fully understand the behavior of the system, showing which are the main variables and suggesting how to intervene in an efficient and effective setting of control technology.
These models have a practical use in the industrial field in fact are set using significant approximations in order to obtain a high processing speed and a great ease of use with the parameterisation of the boundary conditions, and still get a precise model.
The study of the thermodynamic and heat transfer phenomena inherent in the operation of the Flash Cooler formed the basis for the identification of new innovation, both application already controllable than controls with new implementations.
The choice of the values of the gains of the PID is a very important aspect that is adequately accurate in order to characterize the different machines according to the desired response. The knowledge of the particularities of operation, also in relation to the properties of the fluids, has been exploited for the development of computer tools of valid help to the designer, the reliability of which has been ascertained by means of a comparison with the results of a campaign experimental tests.
From the economic point of view is easy realizing that the efficiency achieved through the simple implementation of the control of the modulating valve of the steam present at the input of the thermocompressor. The simulated system and the real system was compared and was calculated by the difference between the flow rate of steam required and superheated steam currently used: in the worst case the surplus reaches more than 100%.
The considerations mentioned briefly suggested guidelines to which the project activity must follow, the purpose is to improve performance, that an improvement of other important aspects, such as compactness, safety, durability, reliability , the low cost. The work carried out, to the extent of the ideas offered, then wants to act as a base for the development of innovative solutions that achieve energy savings compared to traditional solutions.
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