Papers by Author: Priciane Martins Parreira

Abstract: Milk of lime is used in the sugar industry for pH correction and as auxiliary of flocculation in bleaching of the sugar solution. Despite its intense use in sugar cane industry, the milk of lime is rudimentarily produced. The milk of lime badly produced adds great quantities of incrustation in process pipelines and equipments and increases its specific consumption in the process. To mitigate these undesirable effects it is necessary to prepare a milk of lime with appropriated chemical, physical and morphological characteristics. In this paper, several different suspensions of milk of lime were tested in bleaching of the sugar solution. These suspensions were characterized chemical, physical and morphologically and the results were correlated with the performance of the bleaching of the sugar solution. Experimental results showed chemical composition, reactivity, particle size, surface area and slaking process of quicklime affect greatly the quality of the milk of lime.

Abstract: The use of biomass for energy generation has aroused great attention and interest because of the global climate changes, environmental pollution and reduction of availability of fossil energy. This study deals with pyrolysis of four agricultural wastes (sawdust, sugarcane straw, chicken litter and cashew nut shell) in a fixed bed pyrolytic reactor. The yields of char, liquid and gas were quantified at 300, 400, 500, 600 and 700oC and the temperature and pressure effects were investigated. Pyrolytic liquids produced were separated into aqueous and oil phases. XRF spectroscopy was used for qualitative and quantitative elemental analysis of the liquids and solids produced at whole temperature range. Calorific value analysis of liquids and solids were also performed for energy content evaluation. Experimental results showed sawdust, sugarcane straw and cashew nut waste have very good potential for using in pyrolysis process for alternative fuel production.

Abstract: Phosphogypsum or chemical gypsum is a by-product generated in the manufacture of phosphoric acid, generated in the proportion of 4 to 6 tons for every ton of acid produced by the fertilizer industry. Its reuse is important from the economic, social and environmental point of view. The purpose of this paper is to investigate the thermodynamic condition of sulfur dioxide recovering from thermal decomposition of phosphogypsum. The main advantage of this process is to return the sulfur dioxide to sulfuric acid manufacturing. In this case, sulfur demand by fertilizer industry and phosphogypsum generation could be greatly reduced. Experimental results were obtained from a lab scale rotary kiln. Theoretical approach and experimental setup were validated by using the actual data from thermal decomposition of limestone. Theoretical and experimental results showed the thermal decomposition of phosphogypsum is thermodynamically feasible only at high temperatures.

Abstract: Slaked lime is a suspension of hydrated lime in water that can contain up to 40% of solids in suspension. The quality of the suspensions of slaked lime depends on the quality of lime used and on a careful choice of the conditions during the hydration process. A high quality slaked lime is a product with a small quantity of insoluble residues, high specific surface area, high alkaline content and small particle size. Therefore, the objective of this work was to study the best conditions of temperature and concentration to produce a superior slaked lime. A statistic analysis was performed using the experimental results in order to optimize the operational conditions of the hydration process. The use of hydration water around 74 °C, of small particles of CaO (0.144 mm) and of a CaO/H2O ratio around 220 g/L contributed to the production a slaked lime suspension of fine quality.

Abstract: Scrap tire is considered an environmental concern with inadequate final disposal. A good alternative can be to use the tire as an energy source. Pyrolysis is a thermal process that can transform the rubber portion of used tires into oil, gas and pyrolytic carbon. This type of carbon can be converted into carbon black (CB). The lime industry that demands great amount of energy could be one of the ways to take advantage the scrap tires adequately as energy source. This work aimed to study the operational conditions of the pyrolysis process as well as investigating the possibility to use the pyrolysis products from used tires as industrial fuel. A batch pilot-scale pyrolysis unit was built. Temperatures from 400 to 600oC and relative pressures from 0 to -500 mmHg were investigated in order to evaluate product distribution and quality. Experimental results showed that as the reactor temperature was increased the pyrolytic carbon yield remained constant with a mean of 39.8 wt % and the pyrolytic oil yield reached a maximum value of 45.1 wt % at 500 °C. It is also possible to show that the pyrolytic oil can be used as liquid fuels because of its high heating value (40-42 MJ/kg), excellent viscosity (1.6-3.7 cS), and reasonable sulfur content (0.97-1.54wt %). In addition, chemical and physical characterization was made in order to compare the pyrolytic carbon and oil with currently fuels used in Brazilian lime industries (wood charcoal and coke of petroleum).