Otimização do processo de segundo aquecimento do caldo de cana em aquecedores tubulares de uma usina açucareira para organização de um cronograma de limpeza

Abstract

In the sugar-energy sector, the efficiency of industrial operations is one of the most relevant factors, because it is from this that the entire transformation process is impacted. The manufacture of crystal sugar involves several heat exchanges processes, and after the cane is milled, the sugarcane juice goes through the first heating process, aiming to reach 60 ºC to enter the sulfitation stage. Subsequently, the second heating process takes place, aiming to reach a temperature of 105 °C in the broth to be taken to decantation. The equipment used is tubular heaters and tube damage is the main problem, either by irreversible incrustation or corrosion, and for this reason, with a certain frequency the tubular heaters are stopped for cleaning, but the industrial process doesn’t stop, which naturally impacts the heating system as a whole, because when the stop is made, the heat exchange area available for the operation is reduced. Thus, the study aimed to evaluate the relationship between the sugarcane juice final temperature and the heat exchange area available in the second heater, in order to establish a qualitative model of the system behavior, to structure a cleaning schedule of 13 tubular heaters of a sugar mill located in a city in the state of São Paulo. The methodology applied in the development of the work shortened four stages: hypothesis of result, elaboration of the model, validation of data, definition of the best work system. It was based on a theoretical hypothesis of the expected linear effect. It was evidenced that the model didn’t represent the real values, exhibiting second order polynomial behavior. The analysis and treatment of data by arithmetic means served as the basis for establishing a real system behavior model. The validation ensured that it can be used for decision-making in an industrial process, as it presented reliability 98.65%. Thus, a schedule of cleaning of tubular heaters was structured, obtained by the best combinations of stops of heaters, based on the double sets of stationary equipment that reflects in similar conditions of response in the temperature of the sugarcane juice.