Análisis y mejoras de la automatización del evaporador Scheffers en una industria láctea
Analysis and enhacement of Scheffers evaporator automation in a dairy industry
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AuthorClaver Sánchez, Amador
The milk powder facilities of the factory Nestle La Penilla covers from the reception of the milk to the dryer and dry mix of the different products. Milk from Nestle farmers is analyzed to check its quality, if everything is correct the milk undergoes thermization, which consists of a heat treatment to reduce the microbial flora for further storage in silos. Milk is standardized and is treated in the evaporator, which aims to reduce the amount of water. In the dairy industry, the evaporation is used to concentrate products like milk, skimmed milk and dairy whey. It is also used as a preliminary treatment before drying. Dissolved solids in milk do not evaporate, so there is an increase of the concentration in the liquid phase. To perform this operation triple effect falling film evaporator plus a finisher is used. The objective of this project is to increase the evaporator capability. There are several points to improve: i) Increase the mass flow treated for each product, in the case of condensed milk from 7.500 L/h to 8.000 L/h and in products like 1% milk Sveltesse and 26% milk from 7.800 L/h up to 8.000 L/h. ii) Reduce the time required for sterilizations. iii) Optimization of operating conditions. However, this objective is subjected to the following restriction: the quality of the product, measured as the amount of total solids at the evaporator outlet, a theoretical 75% for condensed milk and 44% to 1% and 26% milk respectively, has to be maintained. The DMAIC (Define, Measure, Analyze, Improve and Control) methodology, used by Six Sigma, is used systematically in the company Nestle to solve problems appearing during operation. DMAIC methodology is divided into five stages that are solved iteratively. Therefore, this is the methodology employed in the present work. It has been observed and reported that the overall efficiency and production is improved due to automation. So, control loops, process sequences or valves and pumps operation have been modified in this work. The main result of the project has been achieved because the capability of the evaporator has been increased, so now it can be operating 350 hours more. This is due to an increase in the flow of the products to 8.000 L/h and because the sterilization time has been reduced at an average of 47,3 minutes for sterilization. Savings in water consumption have been also obtained, corresponding to 114,5 m3/yr due to reduced sterilizations and 1.260 m3 per year in the automation, which represents 1.374,5 m3/yr. An increase in the temperature of the separator finisher has been achieved up to an average of 52°C, which allows, together with the enhancement in the milk distribution into the evaporation tubes due to the increment of flow, a reduction in the pressure of the thermocompressor about 0,5 bar. All these improvements have been carried out without affecting the quality of the product.