Análise da sulfidez no processo kraft em uma indústria de celulose

Abstract

The Brazilian industry of pulp is one of the most industries that gives great financial returns to the country because of the lowest production costs in the world. In the past years, these industries have been investing in technologies aimed to reduce the specific consumption of wood and chemical inputs for pulp production. These investments are also used to minimize the disposal of Total Reduced Sulfur - TRS - gases to atmosphere and also maximize the consumption of biomass and chips for power generation. Besides investing in technologies, it is necessary to study about the variables of the process that have most influence at these factors. So, it is important to identify their behavior at the process and to figure out which value will show a great performance without bringing new issues. One of the most important variable in the cooking process is the sulfidity. It is a process variable present in the white liquor, which is responsible for the cooking of the chips inside the digester, and interferes basically in the consumption of chemicals inputs of the process, in the consumption of the wood, in the gases emission and in the energy generation. The objective of the present work is to evaluate, through a case study, the impact of the sulfidity in the pulping process for eucalyptus wood using the technology of Lo-Solids ® type. For that, some analyzes of cellulosic pulps were performed with sulfidity between 32 to 42% and kappa number of 18 ±1. From the collected data, it was studied the relationship between sulfidity and kappa number, viscosity, yield, consumption of chemicals inputs, specific consumption of wood, TRS emission and energy generation. Some of them were made with the aid of Minitab-18 statistic software, using the linear regression analysis simple or multiple. In addition, an economic analysis was carried out regarding the cost of the wood, oil cost, soda cost and lime cost to conclude the best sulfidity value to be worked in the industry, reducing the cost without losing the quality of the final product. After all results obtained from the analyses, it was concluded that the good sulfidity to be used in the industry are 38,5% and 39,5%.