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In distillation, transient behavior cannot be completely eliminated, even with the application of advanced controllers, because the operation in stages imposes the propagation of corrective action throughout whole unit. In previous studies, a control strategy was proposed that uses a combined action between reboiler and heating tray in stripping section of the column aiming to minimize transient operation in distillation. In this work, using the commercial simulator Aspen HYSYS Dynamics, the application of this control strategy was evaluated and it was compared with one testing a distributed cooling action applied to a tray of the rectifying section. Both strategies were also compared with a conventional dual temperature control system when disturbances in the feed temperature were performed. Results had demonstrated a reduction in transition time in bottom and top temperature control loop when distributed strategy was use, either when heating or cooling actions were taken. Internal variables were analyzed in order to verify alterations in flows. Steady state profiles of temperature and ethanol composition were not modified in relation to that obtained with conventional actions, indicating that the proposed distributed strategy only influences transition time.

Among lignocellulosic materials, the waste generated in banana cultivation, such as the discarded fruit, peels, leaves and pseudostem demonstrates great potential for ethanol production. After hydrolysis, a concentration step of the hydrolyzate material is carried out to increase the amount of sugar available for the subsequent fermentation process, which is directly related to ethanol production. Despite being widely employed, the concentration continues to demonstrate certain limitations with respect to its use for cellulosic materials in second generation ethanol production due to the high energy consumption. Besides, the use of banana waste is not completely established, so studies concerning this process are important to evaluate all productive routes. Based on this, simulations of concentration of sugar from hydrolyzed lignocellulosic banana waste were carried out using the software Aspen HYSYS ®, aiming to obtain a concentrated broth containing 65 g/L of sugars with a simple evaporation system operating an atmospheric pressure. Same conditions were used to compare these results with a multi-effect evaporation system. Glucose concentration, the total amount of available sugars and inhibitors concentration were evaluated. Results have demonstrated that the energy consumption with multi-effect evaporator system is low with all residues: discarded fruit (636 kJ/h), banana peels (720 kJ/h) and pseudostem (734 kJ/h). Similar behavior was found for steam requirement: respectively 0, 2397 kg/h 0.3317 kg/h 0.3385 kg/h. As it is known, this is due to the fact that the steam generated in the first effect is used as heating fluid of the next effect. Even the multi-effect system proposed did not reach the 65 g/L of glucose with all residues, it is considered better than a single evaporator because the hydrolyzate streams contain additional sugars that can also be metabolized to ethanol during fermentation.

Lignocellulosic wastes have stood out in the study and development of processes aimed at producing biofuels. Brazil is one of the world’s largest food producers and ranks fifth in world production of bananas with an average production of seven million tons per year. For each ton of bananas harvested, around four tons of lignocellulosic wastes are generated, among which 75% consists of banana plant pseudostem. This work investigated the production of bioethanol by Saccharomyces cerevisae using this residue (pseudosteam) as a fermentation substrate previously hydrolyzed under the following conditions: (a) 250 g/L of fresh biomass (equivalent to 11.75 g/L of dry matter) cut into about 1 mm long pieces and (b) 70 g/L of dry and milled biomass (drying in 60 ºC forced air draft tray dryer and milling in Solab knife mill until particles of size smaller than 30 mesh). The biomass pre-treatments with H2SO4 2% m/m and NaOH 3% m/m, both conducted at 120 °C, 15 min were evaluated. For saccharification of the pre-treated biomass, enzymatic hydrolysis (24 h, pH 5.5, 45 °C) using Novozymes® enzymatic complex composed of cellulase, beta-glucosidase and xylanase was used. The experiments were conducted in Erlenmeyer flasks containing 100 mL of work volume. The greatest percent yield in glucose (YRS = 79.5±4.4 %), calculated based on the theoretical yield of cellulose hydrolysis to glucose (1.1 g/g), was obtained with fresh biomass pre-treated with NaOH. This value was 84% higher than the percent yield resulting from the pretreatment of 70 g/L of dry biomass with the same type of hydrolysis catalyst (YRS = 43.2±1.2 %) and 31% higher than the value reached in the pretreatment of this same biomass with H2SO4 (YRS = 60.7±6.7%). The maximum RS value in hydrolyzed liquor (without prior concentration by evaporation) was obtained from dry biomass saccharification with H2SO4 (26.6±1.1 g/L). The fermentation of this liquor, after concentrating to RS = 62.1 g/L, resulted in an ethanol production of 22.1±0.8 g/L with respective values of YP/RS = 0.47±0.03 g/g, ethanol productivity (QP) 1.83±0.12 g/L.h and effectiveness of alcoholic fermentation (EP) 80.4±0.12 %.

The use of agricultural and agro-industrial waste as biomass fuel for power generation like briquettes can be an alternative solution to the problems related at their disposal. Briquettes produced from lignocellulosic waste, through a simple process and low cost are an excellent source of cheap energy and environmentally correct, in many cases, ideal for replacing fossil fuels in use today, with significant economic and environmental advantages. The banana cultivation generates a significant amount of waste, but little used, it would be important to add value to them. In this work banana semi-dried leaves were crushed to particles with sizes between 2 and 5 mm and its moisture content was determined. The briquettes were produced in a hydraulic press with compaction pressure of 18 MPa and two different compression times and were evaluated by proximate and ultimate chemical analysis, high heating value (HHV), thermogravimetric analysis (TGA), differential thermal analysis (DTA), linear shrinkage, mechanical compressive strength, bulk and energy density. Briquettes presented moisture content of 7.2%, high contents of carbon (44.3 %) and volatile matter (75.3 %), low sulphur and nitrogen contents and HHV of 17.7 MJ/kg. These results are similar for other biomass used to produce briquettes. Under combustion in TGA and DTA analysis, the briquettes showed high loss mass and maximum energy release between 200 and 500 °C. The mechanical compressive strength for 1 second compression was 5.3 MPa and the briquettes density was 0.99 g/cm3. The thermal properties and physicochemical characteristics of the banana leaves briquettes demonstrate its potential for use as biomass fuel.

New alternatives for alcohol production from low-cost feedstocks, such as lignocellulosic biomasses, have been proposed. Banana wastes are an example of these substrates. Existing applications involve the use of the fruit, leaves and other residues, such as the pseudostem. Centrifugation is commonly used for the separation of the solids in the fermentation broth. However, due to the presence of banana residues in the broth, it is necessary to evaluate whether the solid-liquid separation method interferes with the composition of the clarified broth (wine) that is sent to ethanol recovery by distillation. Based on this scenario, the objective of this study was the characterization of the liquid and solid phases for three separation methods: centrifugation, vacuum filtration and microfiltration. Centrifugation was performed at 3800 rpm.min-1 for 20 min and vacuum filtration was conducted with the fermentation broth poured through a filter paper in a Buchner funnel. Microfiltration was performed using a capillary membrane module (polyimide) at room temperature with a flow rate of 90 L.h-1. The loss of ethanol in the liquid phase was evaluated for each method; no differences among the methods were observed. Few differences in the clarified broth composition were verified after centrifugation compared with vacuum filtration and microfiltration. For the removal of solids, microfiltration resulted in a minor presence of total solids in the liquid. These results support microfiltration as a potential method for the separation of solids and liquids in fermentation broth from banana waste. Similarly, the moisture content, Chemical Oxygen Demand (COD), Total Nitrogen (TN) and pH were determined for the solid phase that was discarded after the separation. The highest COD and moisture contents and the lowest value of TN were obtained with microfiltration. The solid residue should be characterized with respect to other constituents and properties to assess their use in processes such as biogas production.

Banana waste has been used to produce bioethanol with the goal of developing a low-cost, sustainable production method. Brazil, which annually generates large amounts of agro industrial waste, has high technological potential in this area. The pseudostem, peel and the fruit can be used and studies are focused on the hydrolysis because it has been proven that this step involves the highest production cost. The goal of this study is to evaluate the acid hydrolysis of banana residues using simulation. It was used the Aspen HYSYS® software simulating the heating, hydrolysis, neutralization and cooling process, from experimental data previously evaluated. A conversion reactor was used and the reactions of cellulose to glucose and that to the hydroxymethylfurfural (HMF) were implemented. Calculation was made in order to obtain the conversion for the optimum conditions of previous work: 120°C, 2 % (weight) H2SO4 and residence time in reactor of 15 min. For these conditions a conversion of cellulose to glucose of 36 % can be obtained when pseudostem was used. Tests were performed with this value for three residues mentioned and then the conversion was increased gradually to the maximum value (100 %). Even known that the conversion of lignocellulosic residues is around 40-60 %, we aimed to corroborate the results previously obtained in the laboratory with data that have not been evaluated experimentally, as the energetic condition of the process and HMF production. The analysis of the energy consumption per sugar produced demonstrated that the hydrolysis of banana fruit residue (pulp) is unattractive as shown experimentally. This behaviour is independent of the increased conversion process. For hydrolysis of the pseudostem was observed that there is a decrease in the amount of energy required in respect of glucose produced to near 80 %, from which the gains with increasing conversion are few.

Steel is widely used in various applications due to its resistance to mechanical stress and its ductility, as well as having other important features such as weldability, paint adhesion, easy molding and recycling, low cost and ferromagnetic properties. With exposure to humidity and high temperatures, however, rust occurs on the steel surface, causing the material to deteriorate. There are various techniques used to protect steel against corrosion, including Hot-Dip Galvanization, which consists of heating a metallic steel sheet in an oven to approximately 600 °C followed by immersing the sheet in a kettle containing an alloy of molten aluminum, iron and zinc. A rectangular metallic structure, known as an electromechanical immersion tunnel (snout), is used for the transfer of the steel metal sheet from the oven to the bath. It is important to prevent the bath oxidation resulting from the contact of the bath with air (dross) because this phenomenon causes a defect visible in the metallic sheet. This can be minimized by controlling the position of the snout. In this study, a mathematical model was implemented to control the angular and linear position of the snout. The automatic reset mode is activated when the rear roller is replaced, while the automatic mode is always used when there are variations in the zinc bath level. The obtained results confirm the effectiveness of the positioning of the equipment showing a minimization of the time required for new adjustments. This proposal reduces the weight of the scrap generated by 27.54 % and 4.75 % for the formation of PGZN (zinc grains) and PBOR (dross), respectively.

The banana culture wastes, leaf and pseudostem, can be used to produce briquettes as fuel for energy generation. The northern region of the Santa Catarina State in Brazil, more precisely in the Joinville city, presents a significant production of bananas, with a harvest of 24,300 t (2010/2011), with 900 hectares of planted area. From the total of harvested bananas 1.5 t of leaves and 2.5 t of pseudostem are generated per ton of produced banana. In this context, this article presents the preparation steps and characterization of banana wastes (leaves and pseudostem) for the production of briquettes. The wastes and briquettes were evaluated by chemical analysis, high heating value (HHV) as well as by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). It was also evaluated the mechanical compressive strength of the briquettes. The moisture content in the wastes for briquetting must be between 8 and 15 %. The banana leaves and pseudostem showed carbon contents of 43.28 % and 38.92 %. The HHV of the leaves was approximately 17.10 MJ/kg and of the pseudostem it was about 13.70 MJ/kg. Under combustion, the wastes showed maximum release of energy at approximately 580 °C and briquettes at 300 °C. The briquettes of pseudostem and leaves presented compressive strength of 15 MPa and 5.3 Mpa, respectively. The thermal properties and physicochemical characteristics of these wastes demonstrate that they are potential candidates to produce briquettes as fuel in several applications.

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