Economic and environmental benefits by improved process control strategies in HCl removal from waste-to-energy flue gas.

The control of HCl emission in waste-to-energy (WtE) facilities is a challenging flue gas treatment problem: the release of HCl from waste combustion is highly variable in time and the HCl emission standards are typically far lower in WtE than in any other industry. Traditional process control approaches in dry HCl removal processes are generally based on feeding a large excess of solid reactants to the system, to ensure robustness and a wide safety margin in the compliance to environmental regulations. This results in the production of a high amount of unreacted sorbents, strongly increasing the generation of solid wastes that need to be disposed.

Techno-economic performance of HCl and SO removal in waste-to-energy plants by furnace direct sorbent injection.

With the impending release of Best Available Techniques (BAT) conclusions on waste incineration, existing European waste-to-energy (WtE) plants will be required to achieve a higher efficiency in the removal of several target pollutants, such as acid gases (above all, HCl and SO). The direct injection of a sorbent in the furnace as a primary deacidification stage may be a cost-effective option to achieve the required performances. The present study investigated the furnace injection of a specific dolomitic sorbent, with the aim of identifying the techno-economic optimum for the sorbent feed rate considering different scenarios of flue gas composition.

Comparison of alternative flue gas dry treatment technologies in waste-to-energy processes.

Acid gases such as HCl and SO2 are harmful both for human health and ecosystem integrity, hence their removal is a key step of the flue gas treatment of Waste-to-Energy (WtE) plants. Methods based on the injection of dry sorbents are among the Best Available Techniques for acid gas removal. In particular, systems based on double reaction and filtration stages represent nowadays an effective technology for emission control.

The assessment of the damage probability of storage tanks in domino events triggered by fire.

An approach aimed to the quantitative assessment of the risk caused by escalation scenarios triggered by fire was developed. Simplified models for the estimation of the vessel time to failure (ttf) with respect to the radiation intensity on the vessel shell were obtained using a multi-level approach to the analysis of vessel wall failure under different fire conditions. Each vessel "time to failure" calculated by this approach for the specific fire scenario of concern was compared to a reference time required for effective mitigation actions and related to the escalation probability.

A methodology for the quantitative risk assessment of major accidents triggered by seismic events.

A procedure for the quantitative risk assessment of accidents triggered by seismic events in industrial facilities was developed. The starting point of the procedure was the use of available historical data to assess the expected frequencies and the severity of seismic events. Available equipment-dependant failure probability models (vulnerability or fragility curves) were used to assess the damage probability of equipment items due to a seismic event.

The assessment of risk caused by domino effect in quantitative area risk analysis.

A systematic procedure for the quantitative assessment of the risk caused by domino effect was developed. Escalation vectors, defined as the physical effects responsible of possible accident propagation, were identified for the primary scenarios usually considered in the QRA procedure. Starting from the assessment of the escalation vectors, the methodology allows the identification of credible domino scenarios and the estimation of their expected severity.