33964 - Environmental Impact of Energy Systems M

Learning outcomes

The aim of the course is to learn the main environmental impact sources from stationary energy systems ant the available technologies to control pollutants generated by such energy systems.

Course contents

Requirements/Prior knowledge

A basic course on Energy Systems is a strongly suggested requirement.

Fluent spoken and written Italian is a necessary pre-requisite: all lectures and tutorials, and all study material will be in Italian.

 

COURSE CONTENTS

 

Introduction.

Introduction on the World (and the Italian) Energy Scenario based on latest statistical data. Energy resources, energy conversion and environmental impact. The need of quantitative performance indicators.

 

Environmental impact of power stations cooling systems.

Assessment of Thermal power released by power plants.

Water condenser cooling systems. Wet cooling tower. Water consumption. Concentration cycles.

PM emitted by cooling towers, Drift Rate. EPA and Reisman & Frisbie PM emission models.

Dry and wet/dry hybrid cooling towers. The plume.

Air condenser cooling system and comparison with water cooling systems.

 

Air pollutants and formation mechanisms.

Main unit of measure of air pollutants from energy systems: concentrations, dilution and emission factors.

Dispersion of pollutants in air: vertical thermal gradient and air stability.

Gaussian dispersion model to calculate concentration of pollutants in air and soil deposition; point of max concentration.

Formation mechanisms of NOx, CO, HC, SOx and PM form combustion; influence of operative parameters (fuel/air ratio, temperature, etc.).

Main effects of CO, HC, NOx, SOx, O3 and PM released in the atmosphere.

 

Environmental impact of fluids for refrigeration plants.

Issues related with the use of CFC, HCFC. The Ozone Depletion Potential. The use of HFC fluids.

Environmental impact of CO2. Greenhouse effect; GWP and TEWI of refrigerant and cooling plants.

Cryogenic plants and energy/environmental issues.

 

Combustion.

Basic definitions, ignition, equivalence ratio, flammability limits, rich and lean flames. The flame temperature.

Classification of combustion processes: definition of premixed and non-premixed combustion.

Flame propagation in premixed flames. Laminar and turbulent premixed flames. Turbulent diffusion flames.

 

Gas turbine combustors.

Thermodynamic boundary conditions for a gas turbine combustor.

Main design elements and related functions of a gas turbine combustor. Diffuser and combustor pressure drop. Swirler and aerodynamics. Multi-burner combustor architectures. Conventional GT combustor and emission formation.

Techniques for emission reduction in gas turbine combustors and concentration performance.

NOx reduction with water/steam injection.

Design of dry low emission combustors: staging, rich-lean and lean-lean combustors.

Lean Premix concept and Dry Low NOx combustors.

Examples of advanced DLN combustor design.

Catalytic combustors.

Post-combustion emission reduction techniques: SCR and SCONOX systems.

Part-load emissions of gas turbine combustors.

 

CHP environmental impact.

Methods to estimate the environmental benefit of CHP systems in terms of air pollutants.

 

Steam turbine power plants.

USC and conventional steam turbine plants.

Coal fired power plants. Pulverized coal combustion, burners and emissions; low emission techniques: air staging (OFA and BOOS), fuel staging, Flue Gas Recirculation, water/steam injection.

Post-combustion abatement systems: Wet Scrubber (layout and working principle), Dry Scrubber (layout and working principle), electrostatic precipitator (layout and working principle), fabric filters (layout and working principle), cyclone, SNCR. 

The flue gas line with post-combustion abatement systems.

Fluidized bed combustors. Pollutant emissions of FBC. Limestone injection for abatement of SOx.

Coal gasification. Integrated Gasification Combined Cycle (IGCC) systems. The Air Separation Unit (ASU) as a cryogenic plant.

Clean Coal Technologies. Plant layouts.

 

Renewable energy systems.

Geothermal energy and geothermal power plants. Steam and dominant water wells and steam turbine plants. Thermodynamic diagram of a geothermal power plant with double flash stage.

Geothermal/fuel based hybrid power plants.

Wind energy and the Betz limit. Weibull distribution. Aerodynamic efficiency of a wind turbine. Method to estimate the visual impact of a wind farm in off-shore applications.

Integration of wind and gas turbines.

Organic Rankine Cycle (ORC) for waste heat recovery applications.

Readings/Bibliography

Sistemi Energetici - Impatto ambientale, Vol. 3, Pitagora (in Italian),

Foreign students can ask the teacher for English readings, corresponding to the topics in this text.

Teaching methods

Class Lectures on all the Course Contents.

Lectures attendance is recommended, but it is not mandatory to pass the exam.

Visit to specific plants related with the lecture topics.

Assessment methods

Individual oral exam, on the topics of the carried out lectures, with reference to:

1) functional aspects;

2) schemes of systems;

3) quantitative aspects and demonstrations.

The questions are aimed at the following main learning outcomes:

- knowledge of the main pollutants formation from energy systems;

- knowledge of the technologies to control pollutants formation from energy systems, mainly gas turbines, combined cycles, boilers of steam power plants and renewable energy systems.

Higher grades will be awarded to students who demonstrate an organic understanding of the subject, a high ability for critical application, and a clear and concise presentation of the contents.

To obtain a passing grade, students are required to at least demonstrate a knowledge of the key concepts of the subject, some ability for critical application, and a comprehensible use of technical language.

A failing grade will be awarded if the student shows knowledge gaps in key-concepts of the subject, inappropriate use of language, and/or logic failures in the analysis of the subject.

The exam will be grade over the 0-30 range, with 18 the minimum to pass, 30 the maximum. Honor can be assigned.

If the course is part of the integrated course DYNAMIC, CONTROL AND ENVIRONMENTAL IMPACT OF ENERGY SYSTEMS M I.C., the final grade, that will be recorded, will be given by the arithmetic average, rounded to the next whole number, of the marks that the student will have obtained in the courses which make up the integrated course. The final "30 e lode" (30 and honor) is awarded if the candidate has obtained 30 in both modules and the honor in at least one of them.

Teaching tools

The use of overhead projector and pc is considered in order to show the case of complex layouts of the plants and energy systems related with the course contents.

Office hours

See the website of Andrea De Pascale