Avaliação técnico-econômica do branqueamento segundo a sequência ADP
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Data
2017-06-27
Autores
Santos, Rafael dos [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Diferentes sequências e condições de branqueamento têm sido exploradas ao longo dos últimos anos, nos quais o processo em múltiplos estágios tornou-se prática comum nas indústrias. A produção de celulose como um todo é uma atividade industrial que requer alto investimento e produz grande impacto ambiental. Sendo assim, alternativas que auxiliem na sua realização de forma socialmente responsável, economicamente viável e ambientalmente correta são de grande interesse. Este estudo teve como objetivo avaliar a viabilidade técnicoeconômica de uma nova sequência de branqueamento sob condições diferenciadas, em relação às comumente empregadas nas empresas do setor de celulose e papel. Para tanto, uma sequência de branqueamento utilizada em uma indústria do setor foi tomada como referência, sendo os estudos a priori conduzidos em laboratório com finalidade de ser possivelmente implementados em escala industrial. Os estágios que compõem a sequência proposta neste estudo são uma hidrólise ácida a quente (AHT), uma dioxidação (D) e uma peroxidação (P), ao passo que os estágios que compõem a sequência referência são uma hidrólise ácida a quente seguida de dioxidação (AHT/D), uma extração alcalina oxidativa com peróxido de hidrogênio (E+P) e uma dioxidação (D). Os branqueamentos foram conduzidos baseados nas condições industriais praticadas pela empresa parceira, bem como pelas condições descritas pela sequência proposta. Foram utilizadas as técnicas de valor presente líquido e payback como ferramentas de auxílio à tomada de decisão para a análise de viabilidade econômica. Os resultados obtidos mostraram a potencialidade do uso da tecnologia de branqueamento ADP, uma vez que a sequência descrita por esta tecnologia produziu polpa branqueada de qualidade similar à obtida pela sequência referência. A sequência proposta mostrou-se ainda mais econômica, principalmente no que tange a demanda por dióxido de cloro, principal reagente utilizado em fábricas que trabalham sob a premissa de branqueamento livre de cloro elementar (ECF). A polpa branqueada pela sequência ADP apresentou melhores resultados quanto à estabilidade da alvura do que a polpa branqueada pela sequência AHT/D(E+P)D. Do ponto de vista econômico, a implementação desta nova tecnologia de branqueamento em três estágios a nível industrial é completamente viável, sendo os seus resultados de viabilidade econômica destacadamente favoráveis à sua utilização.
Different bleaching sequences and conditions have been explored along the last years, in which the process in multiple stages has become common practice at the mills. The pulp production is an industrial activity that requires high investments and promotes a great environmental impact. Hence, alternatives which help its accomplishment in a responsible social way, economically feasible and environmentally correct are quite desirable. This study aimed to evaluate the technical-economic feasibility of a novel bleaching sequence under differential conditions, in relation to those commonly applied in pulp and paper mills. Therefore, a bleaching sequence used in a mill has been taken as reference, being the studies a priori carried out in laboratory with the intention of being possibly implemented in industrial scale. The stages that make part of the sequence proposed in this study are hot acidic hydrolysis (AHT), dioxide stage (D) and peroxide stage (P), while the stages that make part of the reference sequence are hot acidic hydrolysis followed by a dioxide stage (AHT/D), oxidative alkaline extraction with hydrogen peroxide (E+P) and a dioxide stage (D). The bleaching processes were carried out based on industrial conditions practiced by the partner company, as well as by the conditions described by the proposed sequence. Net present value and payback techniques were used as making-decision supporting tools in the economic feasibility analysis. The obtained results show the potentiality of the ADP bleaching technology usage, once the sequence described by this technology produced bleached pulp of similar quality to the reference sequence. The proposed sequence is also more economic, mainly regarding the chlorine dioxide demand, the main reagent used in mills that work under the premise of elemental chlorine free (ECF) bleaching. Pulp bleached by ADP sequence presented better results regarding brightness stability than pulp bleached by A/D(E+P)D sequence. Over economic point of view, the implementation of this novel bleaching technology in three stages at industrial level is completely feasible, being its results of economic feasibility quite favorable to its utilization.
Different bleaching sequences and conditions have been explored along the last years, in which the process in multiple stages has become common practice at the mills. The pulp production is an industrial activity that requires high investments and promotes a great environmental impact. Hence, alternatives which help its accomplishment in a responsible social way, economically feasible and environmentally correct are quite desirable. This study aimed to evaluate the technical-economic feasibility of a novel bleaching sequence under differential conditions, in relation to those commonly applied in pulp and paper mills. Therefore, a bleaching sequence used in a mill has been taken as reference, being the studies a priori carried out in laboratory with the intention of being possibly implemented in industrial scale. The stages that make part of the sequence proposed in this study are hot acidic hydrolysis (AHT), dioxide stage (D) and peroxide stage (P), while the stages that make part of the reference sequence are hot acidic hydrolysis followed by a dioxide stage (AHT/D), oxidative alkaline extraction with hydrogen peroxide (E+P) and a dioxide stage (D). The bleaching processes were carried out based on industrial conditions practiced by the partner company, as well as by the conditions described by the proposed sequence. Net present value and payback techniques were used as making-decision supporting tools in the economic feasibility analysis. The obtained results show the potentiality of the ADP bleaching technology usage, once the sequence described by this technology produced bleached pulp of similar quality to the reference sequence. The proposed sequence is also more economic, mainly regarding the chlorine dioxide demand, the main reagent used in mills that work under the premise of elemental chlorine free (ECF) bleaching. Pulp bleached by ADP sequence presented better results regarding brightness stability than pulp bleached by A/D(E+P)D sequence. Over economic point of view, the implementation of this novel bleaching technology in three stages at industrial level is completely feasible, being its results of economic feasibility quite favorable to its utilization.
Descrição
Palavras-chave
Branqueamento livre de cloro elementar, Sequências curtas, Estabilidade de alvura, Avaliação econômica, Payback, Elemental chlorine free bleaching, Short sequences, Brightness stability, Economic evaluation