Modelling, control and supervisory optimization of generalized predictive control in catalytic cracking reactor

As gasoline demand increases, the efficiency of operation of Fluidized Catalytic Cracking Unit (FCCU) becomes paramount importance. In this paper, a dynamic model for FCCU is simulated and integrated with yield model in order to estimate the yield of products namely gasoline, light gases and coke. Conventional PI controllers are designed for the control of reactor and regenerator temperature. Since, the complete reaction occurs in a very short duration, the controllers are tuned so as to achieve shorter settling time and minimum overshot. Further in order to increase the yield, optimization of FCCU using Generalized Predictive Controller (GPC) at supervisory level is attempted. Through optimization of objective function, the GPC will provide optimized set point for the PI controller in order to maintain maximum gasoline yield.

Modeling current and future role of agricultural waste in the production of bioethanol for gasoline vehicles

This study addressed the urgent need for biofuels even in countries such as Iran, which has fairly good fossil fuel resources. The problems, necessities of the present, and future demand for biofuels are discussed. As the transportation sector is one of the largest sources of air pollution, this study has focused on this sector. This issue was examined from a global perspective, and then within the context of domestic bioethanol production using agricultural residues and proposing different scenarios. The first step in implementing this policy is the accurate forecast of the demand for second-generation bioethanol in the coming years. A nonlinear auto regressive neural network was applied to predict gasoline demand based on Mackey-Glass chaotic time series. Gasoline demand is forecasted by 2030, based on projected volumes of gasoline in different bioethanol mixture scenarios. Results revealed that using scenarios E10, E15, E25, the volume of bioethanol needed by 2030 will amount to 10.12, 15.16 and 25.31 million L per day which can be produced using agricultural products wastes.

Estimation of a Heterogeneous Demand Function with Berkson Errors

Berkson errors are commonplace in empirical microeconomics. In consumer demand this form of measurement error occurs when the price an individual pays is measured by the (weighted) average price paid by individuals in a group (e.g., a county), rather than the true transaction price. We show the importance of Berkson errors for demand estimation with nonseparable unobserved heterogeneity. We develop a consistent estimator using external information on the true price distribution. Examining gasoline demand in the U.S., we document substantial within-market price variability. Accounting for Berkson errors is quantitatively important. Imposing the Slutsky shape constraint reduces sensitivity to Berkson errors.

Is Sugarcane a Convenient Feedstock to Provide Ethanol to Oxygenate Gasolines in Mexico? A Process Simulation and Techno-Economic-Based Analysis

Sugarcane is a major crop produced in many tropical countries including Mexico and has been the basis of a well-established agroindustry. However, the variation in market prices and health concerns over the consumption of sugar are challenging the economics and sustainability of sugarcane growers and mills. This paper presents a techno-economic assessment of using existing production capacity of sugarcane in Mexico and the correspondent Mexican sugarcane mills for producing ethanol as gasoline oxygenate, in comparison to the export of excess sugar production. Using the most recent statistics, we found out that the bioethanol potential is of 849,260,499 L/year which can cover for 100% of the premium and magna gasoline demand in metropolitan area (MA) and 48% of premium gasoline in rest of the country areas (RoCAs) at 5.8% w/v blending (2.7% O2 w/v). This can be done by diverting the 20% sugar production excess to ethanol with the benefit of a higher gross netback of 308.3 USD/ton of sugarcane in comparison to 222.5 USD/ton of sugarcane when it is exported. Furthermore, a minimum ethanol-selling price (MESP) of 0.5211 USD/L was estimated, showing that ethanol might be competitive against methyl tert-butyl ether (0.50 USD/L FOB Gulf price) as gasoline oxygenate agent. Decarbonizing gasoline in Mexico through the use of ethanol might allow the abatement of 5,766.8 kg CO2/day when 20% sugar is used. Concerning the underconstruction Dos Bocas refinery in Tabasco State, southern Mexico, ethanol blend at 5.8% in gasolines might but also contribute to the abatement of 6.1% of CO2 emissions and the required sugarcane was estimated at 1 million tons per year. All these indicate that sugarcane has a great potential as a feedstock to produce first-generation ethanol as a gasoline oxygenate agent in Mexico.

Energy consumption and atmospheric emissions from refined petroleum in Mexico by 2030

One of the basic needs for a country’s economic development is to cover the major fuel demand, and both energy consumption and environmental impacts resulting from the production of such fuels need to be fast and reliable. The purpose of this paper is to contribute to an estimate of energy consumption and atmospheric emissions of some of the pollutant species reported by Pemex Refinacion under different projections. The predictive estimate model was applied considering four different gasoline demand scenarios, as well as different refining technology options to satisfy fuel consumption needs, based on production yields: four different types of refineries, three types of crude oils and eight different processes. Emission estimates were determined applying emission factors, both for the type of fossil fuel energy source used in the direct heating processes for vapor generation, as well by using electric energy. Results show that the equivalent energy consumption relative to the total processes crude is greater in complex refineries (full conversion); however, a greater conversion efficiency allows a smaller volume of crude consumption needed to satisfy the fuel demand with lower emissions relative to other types of technologies. Mexico’s possible refineries need to adapt themselves to different operation scenarios, such as changes in the crude’s yield, the quality of the product, variations in the prices of the crude and of the refined products. Therefore, is important to develop and apply perspectives than maximize productivity and minimize energy consumption, reducing air emissions, in constant change scenarios. Finally, the problem would then be evaluating which would be more convenient to obtain a greater socio-economic benefit: reduce emissions to the atmosphere or to lower operation costs of the refinery.

Gasoline Demand Elasticities at the Backdrop of Lower Oil Prices: Fuel-Subsidizing Country Case

This study investigates the income and price elasticities of gasoline demand for a fuel subsidizing country case, applying three different time-varying coefficient approaches to the data spanning the period from January 2002 to June 2018. The empirical estimations concluded a cointegration relationship between gasoline demand, income, and gasoline price. The income elasticity found ranges from 0.10 to 0.29, while the price elasticity remains constant over time, being −0.15. Income elasticity increases over time, slightly decreasing close to the end of the period, which is specific for a developing country. In the short run, gasoline demand does not respond to the changes in income and price. The policy implications are discussed based on the findings of the study. Research results show that since the income elasticity of demand is not constant, the use of constant elasticities obtained in previous studies might be misleading for policymaking purposes. An increase in income elasticity might be the cause of the inefficiency of the existing vehicles. The small price elasticity allows to say that if policy makers plan to reduce gasoline consumption then increasing its price would not substantially reduce the consumption. The current situation can be utilized to increase energy efficiency and implement eco-friendly technologies. For this purpose, the quality of existing transport modes can be improved. Meanwhile, to meet households’ needs, policies such as providing soft auto loans need to be formed to balance the recent drop in car sales.