Giorgio Ficco

Size distribution and number concentration of particles at the stack of a municipal waste incinerator.

A large number of particles and gaseous products are generated by waste combustion processes. Of particular importance are the ultrafine particles (less than 0.1 microm in aerodynamic diameter) that are emitted in large quantities from all the combustion sources. Recent findings of toxicological and epidemiological studies indicate that fine and ultrafine particles could represent health and environmental risks. Quantifying particulate emissions from combustion sources is important: (i) to examine the source status in compliance with regulations; (ii) to create inventories of such emissions at local, regional and national levels, for developing appropriate management and control strategies in relation to air quality; (iii) to predict ambient air quality in the areas involved at the source and (iv) to perform source apportionment and exposure assessment for the human populations and/or ecological systems involved. In order to control and mitigate the particles in the view of health and environmental risk reduction, a good understanding of the relative and absolute contribution from the emission sources to the airborne concentrations is necessary. For these purposes, the concentration and size distribution of particles in terms of mass and number in a waste gas of a municipal waste incineration plant were measured in the stack gas. The mass concentrations obtained are well below the imposed daily threshold value for both incineration lines and the mass size distribution is on average very stable. The total number concentrations are between 1 x 10(5) and 2 x 10(5)particles/cm(3) and are on average relatively stable from one test to another. The measured values and the comparison with other point sources show a very low total number concentration of particles at the stack gas, revealing the importance of the flue gas treatment also for ultrafine particles. Also in respect to linear sources (high and light duty vehicles), the comparison shows a negligible emission in terms of the total number of particles.

Influential parameters on ultrafine particle concentration downwind at waste-to-energy plants.

A numerical investigation on the parameters influencing the ultrafine particle concentrations downwind an incinerator plant has been carried out on a three-dimensional full scale model. The simulation was based on a modified version of the k-ε turbulence model in order to take into account the thermal buoyancy effect of the plume, and reproducing a stable and neutral atmospheric boundary layer by setting appropriate values of velocity, turbulent kinetic energy and turbulent dissipation rate. The ability of the model to reproduce and maintain a stable atmospheric boundary layer was evaluated by analyzing the turbulent characteristics of the flow along the domain. A parametric analysis made on the basis of different plant operational, environmental, and flue gas treatment parameters was carried out in order to evaluate the impact of incinerator plants on the background concentration of ultrafine particles. The evaluation was made at 5 km downwind the chimney in a breathable area, showing that the most significant impact is due to the flue gas treatment section, with a variation on the background concentration up to 370% for a plant hypothetically working without controls on ultrafine particles emission. Operational and environmental parameters determine variations of the concentrations ranging from 1.62% to 4.48% for the lowest and highest chimney, from 1.41% to 4.52% for the lowest and highest wind speed and from 2.48% to 4.5% for the lowest and highest flue gas velocity, respectively. In addition, plume rise evaluation was carried out as a function of wind speed and flue gas velocity from the chimney.

The influence of the uncertainty on monitoring stack emissions in a waste-to-energy plant

Managing the result of a comparison between measured values and a threshold is usually a relevant issue. An area in which this issue is even pressing is the monitoring of pollutants emitted by plants for the disposal and incineration of waste. This paper proposes a method of comparison that, taking into account both measurement uncertainty and measurand variability, allows to estimate the level of risk that a wrong decision is being taken. The application of the method to the problem of tracking pollutants in the waste-to-energy plant of San Vittore del Lazio (Italy), after a brief description of the plant, is described through some experimental results.

Critical aspects of new domestic static gas meter

To promote the diffusion of smart metering, several National Authorities defined strict roll-out procedures of the existing meters with new smart meters. In such scenario, even if new static technologies in gas metering offer very significant potential (such as digital output, absence of moving parts, direct mass measurement), their reliability in some critical conditions typical of natural gas distribution networks (i.e. zero flow, minimum flow-rate, gas quality changes, presence of dust and contaminants, etc.) still has to be demonstrated. A very promising technology for natural gas domestic measurements is represented by thermal mass flow meters, but, unfortunately, gas quality is expected to significantly affect metrological performance of such meters. The authors conducted several metrological tests aimed to verify the sensitivity of such meter with natural gas quality changes. The results of these tests show a not full reliability when CO2 content increases and when gas composition varies.

Metrological characterization of a new direct heat accounting device

The new Energy Efficiency Directive leads to a strong incentive to the installation of heat accounting systems as an essential tool to increase energy efficiency of buildings. This is also facilitated by the spreading of district heating networks more and more extended and to the return to central heating plants in buildings, more efficient and less polluting than traditional individual ones. Heat metering and accounting is now carried out by the so-called direct systems (i.e. heat meters) and indirect (i.e. heat cost allocators, insertion time counters compensated whit flow temperature or with the degree-days). On the other hand, both the metrological characteristics of such systems and the constraints in terms of installation and managing of heating plants lead direct and indirect systems to uncertainties in heat accounting sometimes far above the accuracy limit of 5%. In this paper the authors present the results of an experimental characterization of an innovative integrated system for heat accounting made up of an electronic valve, a static flow-meter and a temperature sensor pair. The system can be installed on the return pipe of each radiator of the heating plant and connected with a remote control unit and with a single temperature sensor installed on the feed pipe immediately below the central boiler.