Prediction of sulfur content in diesel fuel using fluorescence spectroscopy and a hybrid ant colony : Tabu Search algorithm with polynomial bases expansion

It is widely accepted that feature selection is an essential step in predictive modeling. There are several approaches to feature selection, from filter techniques to meta-heuristics wrapper methods. In this paper, we propose a compilation of tools to optimize the fitting of black-box linear models. The proposed AnTSbe algorithm combines Ant Colony Optimization and Tabu Search memory list for the selection of features and uses l1 and l2 regularization norms to fit the linear models. In addition, a polynomial combination of input features was introduced to further explore the information contained in the original data. As a case study, excitation-emission matrix fluorescence data were used as the primary measurements to predict total sulfur concentration in diesel fuel samples. The sample dataset was divided into S10 (less than 10 ppm of total sulfur), and S100 (mean sulfur content of 100 ppm) groups and local linear models were fit with AnTSbe. For the Diesel S100 local models, using only 5 out of the original 1467 fluorescence pairs, combined with bases expansion, we were able to satisfactorily predict total sulfur content in samples with MAPE of less than 4% and RMSE of 4.68 ppm, for the test subset. For the Diesel S10 local models, the use of 4 Ex/Em pairs was sufficient to predict sulfur content with MAPE 0.24%, and RMSE of 0.015 ppm, for the test subset. Our experimental results demonstrate that the proposed methodology was able to satisfactorily optimize the fitting of linear models to predict sulfur content in diesel fuel samples without need of chemical of physical pre-treatment, and was superior to classic PLS regression methods and also to our previous results with ant colony optimization studies in the same dataset. The proposed AnTSbe can be directly applied to data from other sources without need for adaptations

Food waste biorefinery advocating circular economy : bioethanol and distilled beverage from sweet potato

The exponential growth rate of the global population has been causing a threat to finite resources and also increasing the amount of waste generated. The global quantitative food waste for tubers is 45% per year, which in Brazil would amount to 350,000 tons of sweet potato wasted annually. Food waste causes 10% of the emissions of greenhouse gases. In this work, food waste biorefineries are the proposed solution. Integrated processing via a combination of different technologies to produce both ethanol and distilled beverage was evaluated to valorize sweet potato waste profitably within the circular economy concept. No works concerning the integrated production of both products simulating different real market scenarios were found. Five different scenarios varying the production percentage of each product were evaluated. The higher the production of the distilled beverage, the more profitable the scenarios are. Economic results began to be positive when the production for sale of each product reaches 40%, plus 20% of ethanol for domestic consumption. The scenario with 80% of beverage production presented NPV of US$ 1,078,500.18, IRR of 51%, and discounted payback of 1.06 years. The sweet potato waste biorefinery is a sustainable model and contributes to the development of the agriculture and food sector by providing new businesses and consequent job creation. It also leads to the reduction of greenhouse emissions by producing renewable resources and marketable products, thus reaching the goals of the circular economy

A simple equation for total reducing sugars (TRS) estimation on sweet potato and ethanol yield potential

Sweet potato is an attractive feedstock for ethanol production due to its high starch content and favorable agronomic characteristics. This paper proposes a simple equation to estimate the total reducing sugars (including glucose from starch) in sweet potatoes based on their moisture content (low cost and simple measurement). It allows the calculation of the ethanol production potential of a given sweet potato mash. According to the equation, the ethanol potential increases non-linearly with increasing concentrations of sweet potato mash in the fermenting medium (w/v), reaching a constant value for high concentrations (22 % of ethanol to 10 kg: L of a sweet potato with a moisture content of 66 %). Additionally, the ethanol yield potential is very sensitive to the sweet potato moisture, increasing linearly when the moisture decreases. We emphasize that the relations proposed in this paper can be used by other researchers, who can apply them to their specific cases

Economic evaluation of sweet potato distilled beverage produced by alternative route

Shochu is the most consumed distilled beverage in Japan, produced from sweet potato, one of the most cultivated vegetables in Brazil. Tchêchu is a similar distillate, produced by an innovative process, whose economic viability is the object of study of this work. The cost of producing a bottle (750 mL) of Tchêchu was estimated at US$2.56. The economic evaluation was based on economic indicators that resulted in positive net present value (US$ 530,501.42), internal rate of return (26% p.y.) higher than the minimum acceptable rate of return (9.25% p.y.) and payback of 2.44 years, indicating that the implantation of the distillery is economically viable

Study of rice husk continuous torrefaction as a pretreatment for fast pyrolysis

Rice husk (RH) is one of the most available biomasses in southern Brazil. One possible solution is to carry out the fast pyrolysis of RH. To improve the quality of liquid products biomass can be torrefied before being pyrolyzed. The influence of torrefaction on the physical and chemical properties of pyrolysis products was explored. Both torrefaction and pyrolysis reactions were performed in a fluidized bed reactor in a continuous mode. Sample with torrefaction and pyrolysis at 500 ◦C presented the highest biochar yield (44.2 wt.%). The torrefaction step produced a lower yield of bio-oil. In contrast, the highest bio-oil yield (43.6 wt.%) was achieved in the sample without torrefaction at 500 ◦C. The increase in temperature to 750 ◦C provided a specific area of 16.7 m2 /kg for biochar. The highest value of HHV for bio-oil, 28 MJ/kg, was obtained via direct pyrolysis at 750 ◦C, which also led to the lowest water content of 5.9 wt%. According to the NMR analysis, the torrefaction liquid (TL) presented a high quantity of water and alcohols in its composition (92.5 %)

Reliable and straightforward PID tuning rules for highly underdamped systems

Proportional-Integral-Derivative (PID) controllers reign absolute when automatic control is applied. There is an expressive number of tuning rules for these controllers in literature. However, for highly oscillatory (or highly underdamped) systems, such as the ones found in oil production and polymerization reactors, the available methods provide poor closed-loop performance and robustness. Besides, most of these tuning rules are developed for systems based on a frst-order with pure time delay (FOPTD) transfer function and for parallel form PID controllers. Therefore, the focus of this paper is the development of appropriate tuning rules for highly underdamped systems through non-cancellation of dominant poles and easily adjustable robust performance, making them applicable for both series and parallel PID controllers, since the proposed tuning only places the controller zeros at the real axis. The new tuning rules were developed for these systems and were tested on 15,000 diferent transfer functions described by a second-order with pure time delay (SOPTD) expression. Additionally, a recommendation interval is also provided in which the controller gain can be varied online or by simulations to achieve the desired trade-of between performance and robustness. The proposed rules are also validated using two case studies: the suppression of slugging in oil production and the temperature control of an industrial gas phase polyethylene reactor

An overview of different approaches in hydrogen network optimization via mathematical programming

Goal: Hydrogen has shown increasing demand in oil refineries, due to the importance of its use as a sulfur capture element. As different oils and products require different amounts of hydrogen, their use optimally is an essential tool for refinery production scheduling. A comparison was made between the different approaches used in optimization via mathematical programming.Design / Methodology / Approach: One of the most used methods for hydrogen network optimization is through mathematical programming. Linear and non-linear models are discussed, positive aspects of each formulation and different initialization techniques for non-linear modeling were considered.Results: The optimization through the linear model was more satisfactory, taking into account the payback of the new proposed design, combined with the use of compressor rearrangement, which reduces the investment cost.Limitations of the investigation: The objective function chosen is based on the operational cost, but another approach to be considered would be the total annual cost. In addition, the parameters related to costs are obtained from the literature and may change over the years.Practical implications: The proposal is to discuss the main aspects of each model, showing which models more robust and easier to converge are capable of providing competitive results. Also, different initialization techniques that can be used in future works.Originality / Value: The main contribution is the relationship between hydrogen management and production scheduling and for that, a discussion is made about possible formulations. Linear model is sufficient to optimize the problem, due to its main characteristics discussed

Alternative process for production of sweet potato distilled beverage

Shochu is the most widely consumed spirit in Japan. In its manufacture is used koji, a solid fungus culture traditional of the Asian countries, but that makes the production process slow. Shochu can be produced from a variety of starchy sources, including sweet potato. About 7% of the world’s sweet potato production is wasted due to imperfections that make it unsuitable for consumption. However, this material can be used in ethanol production. Considering the high productivity of sweet potato in Brazil, an opportunity to add value to this raw material is perceived. An alternative process for the production of sweet potato distillate similar to shochu was proposed. Koji was replaced by a mixture of alpha-amylase and glucoamylase. Process time was reduced from 14 to only 1 day. Composition analyses were performed by HPLC and GC. The experimental yield of alcoholic fermentation using pectinase enzyme reached 67.31-73.65%, but methanol was above the limits of the legislation. Without the addition of pectinase, no methanol was formed. However, there was a decrease in yield (51.65-54.75%), due to the incomplete disintegration of sweet potatoes. The distillate produced and the commercial shochu presented the same absorption bands in FTIR analysis, identifying the similarity between them

MILP formulation for solving and initializing MINLP problems applied to retrofit and synthesis of hydrogen networks

The demand for hydrogen in refineries is growing due to its importance as a sulfur capture element. Therefore, hydrogen management is critical for fulfilling demands as efficiently as possible. Through mathematical modeling, hydrogen network management can be better performed. Cost-efficient Mixed-Integer Linear Programming (MILP) and Mixed-Integer Nonlinear Programming (MINLP) optimization models for (re)designing were proposed and implemented in GAMS with two case studies. Linear programming has the limitation of no stream mixing allowed; therefore, to overcome this limitation, an algorithm-based procedure called the Virtual Compressor Approach was proposed. Based on the MILP optimal solution obtained, the streams and compressors were merged. As a result, the number of compressors was reduced, along with the inherent investment costs. An operational cost reduction of more than 28% (example 1) and 26% (example 2) was obtained with a linear model. The optimal MILP solution after rearranging compressors was then provided as a good starting point to the MINLP. The operating costs were decreased by more than 31% (example 1) and 32% (example 2). Most of the cost reduction was obtained only with the usage of the MILP model. Besides, a higher level of cost reduction was only obtained when the linear model was used as the starting point

A circular economy model for ethanol and alcohol-based hand sanitizer from sweet potato waste in the context of COVID-19

Goal: The goal of the present work is to analyze the techno-economic viability of a biorefinery to generate ethanol and alcohol-based hand sanitizer from sweet potato waste within the concept of a circular economy.Design / Methodology / Approach: A survey of expenses for a 1000 L.day-1 distilled plant was carried out, and five different market scenarios were evaluated, varying the rate of production of each product.Results: Results show that the higher the production of the hand sanitizer, the more lucrative the scenarios are. The economic breakeven point occurs when the percentage of the alcohol-based hand sanitizer production is equal to 34%. However, the project becomes economically attractive from the production rate of 39%. The scenario for 80% of alcohol-based hand sanitizer production resulted in NPV of US$ 913,140.92, IRR of 64%, with a discounted payback of 0.72 year.Limitations of the investigation: It was considered that all the production was sold, which is in line with the current market demand. However, if the market slows down, the sales and the revenue obtained may be lower.Practical implications: The production of hand sanitizer from sweet potato waste is an opportunity to meet the market needs in scenarios such as the COVID-19 pandemic. Besides, the proposed biorefinery promotes the development of the circular economy through waste minimization.Originality / Value: No studies about the production of ethanol and alcohol-based hand sanitizer from sweet potato waste in an integrated way and the simulation of different real market scenarios were found