Full text
| |
| Author(s): |
Marcos Augusto Stolf Brasil
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB) |
| Defense date: | 2021-05-05 |
| Examining board members: |
Marcos Yassuo Kamogawa;
Antonio Sampaio Baptista;
Eduardo Poggi e Borges;
Ivo Milton Raimundo Junior
|
| Advisor: | Marcos Yassuo Kamogawa |
| Abstract | |
This work was focus on the study of the conditions, compounds and processes involved in the formation of fouling in the evaporators of sugar mills, their chemical - morphological constitution, ways to reduce their concentration and dissolution. Initially, analyzes of the composition of mixed, clarified row sugarcane juice and incrustations of two plants were carried out in order to evaluate their composition and characteristics. This initial study determined four major elements in the composition offoulings: calcium, phosphorus, magnesium and sulfur. It also determined the existence of a significant variation in the concentration of the juice composition. In a period of 6 hours a variation of 70% in the concentration of calcium was observed. The work continued to seek to correlate the relevance of each of the stages of the juice and input treatment process for the concentration of the elements responsible for the foulings. An automatic flow analysis system was developed to determine calcium and phosphorus suitable to operate in solutions containing a high percentage of suspended and dissolved solids. The system obtained a detection limit of 0.48 and a linear band of 0.50 - 50.00 mg L-1 for calcium and 1.13 and 1.20 - 50.00 mg L-1 for phosphorus, with a frequency analytical of 16 determinations per hour for both.Special attention was given to the lime input, responsible for introducing, through the limeing procedure, the calcium element in the juice, which corresponds to 70% of the composition of the foulings. Eight samples of lime from plants and commercials were studied, as to the composition and important attributes for the treatment of the juice and the formation of foulings. In an experiment, supported by a complete factorial design on two levels (2 ^ 4), the treatment of row sugarcane juice samples was carried out under the standard conditions recommended by the literature and used in the Plants. The independent variables of the study were phosphating, sulfitation, limeing and decanting and aimed to determine the value of the most significant responses in the process. The row sugarcane juice was analyzed prior to treatments for pH parameters, Total Soluble Solids (SST%), Percentage of Oligosaccharides (POL (S)), Turbidity (NTU), Color ICUMSA, Ca and P (mg L-1). The statistical analysis of the data offered a privileged view of the panorama. The juice treatment study and its results served as a basis for another study of the reduction of foulings precursors, which through specific interventions sought to reduce the percentage of foulings precursors. In the process improvement studies, changes in concentrations and partial substitutions of inputs, tests of inhibitors and complexing agents were initially evaluated. These studies obtained a 56% reduction in the concentration of calcium in the juice compared to the standard treatment.The foulings formation study that followed sought to evaluate and compare the fouling effect of a juice clarified by the standard procedure with those obtained by the most promising methodologies for reducing fouling precursors determined in the juice treatment study. Within this study, the action of scale inhibiting agents was also evaluated. In the study of characterization of incrustations detailed chemical and morphological analyzes were carried out by digital microscopy and x-ray fluorescence on the components of the incrustations in order to determine the structure and possible processes involved in their formation. The final stage of the work involved the study to dissolve the incrustations, the efficiency of dissolving agents was evaluated in isolation, in compositions and determined the fractions removed from the incrustation in each study and the remaining active compounds in the tested solutions (AU) | |
| FAPESP's process: | 17/05701-8 - Incrustations in evaporators / concentrators of sugar mills: prognosis of formation, prevention and chemical solubilization |
| Grantee: | Marcos Augusto Stolf Brasil |
| Support Opportunities: | Scholarships in Brazil - Doctorate |