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Estudo da melhoria do desempenho do processo dos lavadores de superfosfatos
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Esta dissertação tem como foco a zona de lavagem dos superfosfatos da SOPAC. A reação de produção de superfosfatos produz gases de flúor que necessitam de ser tratados antes serem libertados para a atmosfera. A limpeza dos gases poluentes na empresa é realizada através de 3 torres de lavagem ocas e um multiventuri, com recurso a água.
A absorção química do flúor com água leva à formação de ácido hexafluorossilícico (H2SiF6) e de dióxido de silício sólido (SiO2).
Foram realizadas análises às variáveis desconhecidas do processo como a temperatura, pressão e concentração de H2SiF6 de forma a desenvolver um modelo explicativo sobre o funcionamento de todo o processo. Através do modelo, o valor das emissões de flúor varia entre os 1 e 4,4 mg/Nm3 e apresenta um erro de ± 5% quando comparado com as análises históricas realizadas pela empresa.
Apesar da instalação se encontrar dentro de especificação ambiental, <5 mg/Nm3 de flúor, através do modelo proposto foi possível simular o pior cenário de 239 mg/Nm3.
De forma a garantir que a empresa nunca esteja em risco ambiental, foi dimensionada uma coluna de enchimento de absorção com uma eficiência de 98,3% modificando o intervalo de emissões de flúor em condições normais para 0,02 a 0,075 mg/Nm3 e no pior cenário para 4,5 mg/Nm3 garantindo sempre o cumprimento da legislação em vigor.
Atualmente não existe nenhum equipamento de remoção dos sólidos formados de SiO2 na zona de lavagem. A acumulação é mais notória e prejudicial no tanque 1 e R onde, no mínimo, 78% dos sólidos totais do processo se acumulam. Foram propostos e dimensionados, através de ensaios de filtração e sedimentação, um filtro de prensas e um decantador de alta taxa com o intuito de minimizar este problema.
O decantador tubular hexagonal revelou-se ser a hipótese mais viável, com uma eficiência na diminuição da concentração de sólidos nos tanques 1 e R de 99%. Este equipamento retira a necessidade de paragens para limpeza, aumentando a produtividade, reduz a variabilidade do processo, a necessidade de mão de obra especializada e mantem a eficiência da zona de lavagem.
This dissertation focuses on the superphosphate washing zone at SOPAC. The superphosphate production reaction produces fluorine gases that need to be treated before being released to the atmosphere. The cleaning of the pollutant gases is carried out in the company by means of 3 hollow washing towers and a multiventuri with the use of water. The chemical absorption of fluoride with water leads to the formation of hexafluorosilicic acid (H2SiF6) and solid silicon dioxide (SiO2). Analyses of the unknown process variables such as temperature, pressure, and concentration of H2SiF6 were performed to develop an explanatory model of how the whole process works. According to the model, the value of fluoride emissions varies between 1 and 4.4 mg/Nm3 and presents an error of ± 5% when compared to the historical analyses performed by the company. Although the facility complies with the environmental specification, <5 mg/Nm3 of fluoride, through the proposed model it was possible to simulate the worst case scenario of 239 mg/Nm3. In order to ensure that the company is never at environment risk, an absorption packed column was proposed with an efficiency of 98.3% modifying the values of fluoride emissions under normal conditions to 0.02 to 0.075 mg/Nm3 and in the worst case scenario to 4.5 mg/Nm3 always ensuring compliance with the legislation in force. Currently there is no equipment to remove the SiO2 formed in the wash zone. The accumulation is more notorious in tank 1 and R where at least 78% of the total solids of the process accumulate. A press filter and a high-rate decanter were proposed and sized, through filtration and sedimentation tests, to minimize this problem. The hexagonal tubular decanter proved to be the most successful hypothesis, by efficiently reducing the concentration of solids in tanks 1 and R by 99%. This equipment eliminates the need for cleaning stops, increasing productivity, reduces process variability, the need for skilled labour and maintains washing efficiency.
This dissertation focuses on the superphosphate washing zone at SOPAC. The superphosphate production reaction produces fluorine gases that need to be treated before being released to the atmosphere. The cleaning of the pollutant gases is carried out in the company by means of 3 hollow washing towers and a multiventuri with the use of water. The chemical absorption of fluoride with water leads to the formation of hexafluorosilicic acid (H2SiF6) and solid silicon dioxide (SiO2). Analyses of the unknown process variables such as temperature, pressure, and concentration of H2SiF6 were performed to develop an explanatory model of how the whole process works. According to the model, the value of fluoride emissions varies between 1 and 4.4 mg/Nm3 and presents an error of ± 5% when compared to the historical analyses performed by the company. Although the facility complies with the environmental specification, <5 mg/Nm3 of fluoride, through the proposed model it was possible to simulate the worst case scenario of 239 mg/Nm3. In order to ensure that the company is never at environment risk, an absorption packed column was proposed with an efficiency of 98.3% modifying the values of fluoride emissions under normal conditions to 0.02 to 0.075 mg/Nm3 and in the worst case scenario to 4.5 mg/Nm3 always ensuring compliance with the legislation in force. Currently there is no equipment to remove the SiO2 formed in the wash zone. The accumulation is more notorious in tank 1 and R where at least 78% of the total solids of the process accumulate. A press filter and a high-rate decanter were proposed and sized, through filtration and sedimentation tests, to minimize this problem. The hexagonal tubular decanter proved to be the most successful hypothesis, by efficiently reducing the concentration of solids in tanks 1 and R by 99%. This equipment eliminates the need for cleaning stops, increasing productivity, reduces process variability, the need for skilled labour and maintains washing efficiency.
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Superfosfatos emissões de flúor acumulação de sólidos coluna de absorção filtro de prensas decantador de alta taxa