Calculations for the sterilization by direct injection of steam culture medium used in the production of HeberNem

Abstract

At present, the process to obtain of HerberNem is in an increase in production capacity. Given the influence of the sterilization process in the current process and the need to find another sterilization method in the new plant it is necessary to establish a methodology to perform energy balances during the process. For this purposes, basic equations of heat transfer and the calculations proposed by the company Spirax-Sarco were used. The "solver" tool of Excel was used to complete the calculations depending on the setting of physical and energy parameters of the system. It was determined that the thermal stress on the current scale of production is equivalent to 76.9 °C h, being the most influential obtained during the sterilization equal to 48 °C h. In the sterilization by injection of direct steam, it was found that had the greatest influence was the inlet steam pressure. During heating, heat stress values obtained were equal to 105,1 °C h, 42,5 °C h and 26,8 °C h, to values of vapor pressure of 2, 5 and 8 bar respectively. While, during cooling a twofold increase in the mass flow of cold water only reduced the 28, 2 % of cooling time. The obtained methodology allows adjustment of the thermal stress on both scales to technological variations during increasing production scale.