Learning distillation by a combined experimental and simulation approach in a three steps laboratory : Vapor pressure, vapor-liquid equilibria and distillation column

Distillation is one of the most important separation process in industrial chemistry. This operation isbased on a deep knowledge of the fluid phase equilibria involved in the mixture to be separated. In par-ticular, the most important aspects are the determination of the vapor pressures of the single compoundsand the correct representation of the eventual not ideality of the mixture. Simulation science is a fun-damental tool for managing these complex topics and chemical engineers students have to learn andto use it on real case-studies. To give to the students a complete overview of these complex aspects, alaboratory experience is proposed. Three different work stations were set up: i) determination of vaporpressure of two pure compounds; ii) the study of vapor-liquid equilibria of a binary mixture; iii) the useof a continuous multistage distillation column in dynamic and steady-state conditions. The simulation ofall these activities by a commercial software, PRO II by AVEVA, allows to propose and verify the thermo-dynamic characteristics of the mixture and to correctly interpret the distillation column data. Moreover,the experimental plants and the data elaboration by classical equations are presented. The students arerequest to prepare a final report in which the description of the experimental plants and experimentalprocedure, the interpretation of the results and the simulation study are critically discussed in order toencourage them to reason and to acquire the concepts of the course.Two different questionnaires each with 7 questions, for the course and for the laboratory, are proposedand analyzed. The final evaluation of the students was strongly positive both for the course as a wholeand for the proposed laboratory activities

Biogas upgrading by physical water washing in a micro-pilot absorption column conducted at low temperature and pressure

The European Energy Policy has currently two main goals to reach: to minimize exposure to volatility of fossil fuel prices and to reduce of greenhouse gas (GHG) emissions. To reach these targets a practical way, among the others is represented by the biogas production by anaerobic digestion (Bonoli et al., 2014) (AD) and its upgrading to biomethane. In this work the absorption of CO2is studied using a column working at atmospheric pressure and low temperature (599%) and a stream of methane (>99.9 %) in order to reproduce a typical raw biogas composition, i.e. molar fraction of methane of about 0.6. The internal temperature was monitored by a thermocouple and the inlet and outlet flow of biogas (G) was measured using a mass flowmeter while the water flow rate (L) was monitored using a magnetic induction flowmeter. The compositions were determined using a 3000A micro-Gas Chromatograph Agilent, previously calibrated. The temperature was varied between 6.5 and 20 °C and the water flow rate between about 0.5 and 5 L/h. The composition of the gas exiting the micro-pilot plant was monitored every 5 minutes until the stationary condition

Use of a sol-gel hybrid coating composed by a fluoropolymer and silica for the mitigation of mineral fouling in heat exchangers

The technology of the organic/inorganic hybrid coating was employed in the preparation of a hydrophobic coating (contact angle higher than 140\ub0) for fouling mitigation on stainless steel heat transfer surfaces. A commercial triethoxysilane perfluoropolyethers was combined with a sol-gel silica network with the aim to increase the mechanical and thermal resistance of the films when exposed to aggressive liquid environments as the heat exchanging fluids. The experimentation on a shell and tube heat exchanger pilot plant confirmed the ability of the hybrid coating to prolong the crystallization fouling induction period of 200 h in respect to an uncoated heat exchanger, operating in the same conditions. Moreover, the fouling particles deposited on the coated heat transfer surfaces had only slight adhesion strength toward the coated surfaces and were easily removed by inducing higher wall shear stresses inside the tubes of the plant

Studying oven technology towards the energy consumption optimisation for the baking process

A recent guideline from the European Commission declared that several highly energy consuming domestic equipment should be better regulated or avoided at all in the near future. Together with this, several EU nations are abandoning the gas ovens in favour of the electric ones, also due to the home energy rating regulations, that make impossible to get the highest rating with gas ovens. Due to this fact, the study of the technologies related to the energy efficiency in cooking is increasingly developing. The combination of several energy sources (e.g. forced convection, irradiation, microwave, etc.), as well as optimisation of each of them, is an emerging target for oven manufacturers, in matter of oven design and better use of the oven capabilities. Within this context, an energy consumption analysis and optimisation is targeted in this work, by the application of a bread baking model, validated on experimental data. Each source of energy is given the due importance and the practically applicable process solutions are compared. A basic quality standard is guaranteed by taking into account some quality markers, which are relevant on the basis of a consumer point of view. This work is a part of a more comprehensive study on oven cooking and energy integration, and could lead to practical applications in the design of energy efficient cooking programs

Optimisation of a Doherty power amplifier based on dual-input characterisation

The success of the Doherty architecture compared to other efficiency enhancement techniques derives mainly from its simple design and full-RF nature, not requiring complex digital signal processing to achieve high back-off efficiency. In this work we propose a design strategy for the optimisation of a Doherty power amplifier to mitigate the typical practical issues of this architecture related to inaccuracy of the non-linear model and of the manufacturing. The approach is based on the experimental characterisation of a dual-input Doherty prototype without input section. This test structure is obtained from a single-input Doherty amplifier, designed only through non-linear simulations, by removing the input section and allowing for separate control of the two RF inputs. From the collected data, approximated functions for the phase shift and power splitting versus frequency are identified to be realizable in hardware with RF networks. Compared to the reference single-input Doherty stage, a significantly improved behavior is registered in terms of output power (up to 2.7 dB), efficiency at saturation and back-off (30 % and 15 % respectively) and power gain (2 dB)

On the topological index of irregular surfaces

We study the topological index of some irregular surfaces that we call generalized Lagrangian. We show that under certain hypotheses on the base locus of the Lagrangian system the topological index is non-negative. For the minimal surfaces of general type with q = 4 and pg = 5 we prove the same statement without any hypothesis

Hybrid Risk-based LCA: An innovative holistic approach to improve the acid gas to syngas (AG2S) process

The sustainable development has recently become the cornerstone of the environmental policy worldwide and a leading principle for resource management. The philosophy lies in a continuous demand of innovative choices able to ensure the existing productive systems survival through a new design paradigm shift. In this regard, the technological innovation should be always driven by the sustainability concept: the economic, societal and environmental impact ought to be continuously fostered to the systems\u2019 sustainable improvement. This demanding goal can be accomplished with a blended Life Cycle (LCA) and Life Risk (LRA) Assessment to highlight the process potential health and environmental impacts. LRA is the process in which imposed risks by the inherent hazards linked to a process are continuously assessed (quantitatively or qualitatively). LCA instead is the process that analyses and assesses the environmental impact of a material, product or service throughout its entire life cycle. LCA and LRA are typically driven by two different approaches, respectively a deterministic and a stochastic approach. This usually drives an unconnected use of LCA and LRA in the quantification of products and processes potential impact and determines controversial decisions with respect to a balance between environmental impacts and operational risks. The new paradigm suggests a unified blended LCA \u2013 LRA approach that is applied at a preliminary stage to an innovative Acid Gas to Syngas (AG2S) process for CO2 emission reduction and on-site reuse, avoiding the costly and hazardous transportation step