1,721,004 research outputs found
Bilanci energetici di impianti di termoutilizzazione in sistemi integrati di gestione dei RSU
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Simulation of the influence of flue gas cleaning system on the energetic efficiency of a waste-to-energy plant
No full textMunicipal solid waste incinerators are designed to enhance the electrical efficiency obtained by the plant as much as possible. For this reason strong integration between the flue gas cleaning system and the heat recovery system is required. To provide higher electrical efficiencies acid gas neutralization process has the major importance in flue gas cleaning system. At least four technologies are usually applied for acid gas removal: dry neutralization with Ca(OH)2 or with NaHCO3, semi-dry neutralization with milk of lime and wet scrubbing. Nowadays, wet scrubbers are rarely used as a result of the large amount of liquid effluents produced; wet scrubbing technology is often applied as a final treatment after a dry neutralization. Operating conditions of the plant were simulated by using Aspen Plus in order to investigate the influences of four different technologies on the electrical efficiency of the plant. The results of the simulations did not show a great influence of the gas cleaning system on the net electrical efficiency, as the difference between the most advantageous technology (neutralization with NaHCO3) and the worst one, is about 1%
Influence of flue gas cleaning system on the energetic efficiency and on the economic performance of a WTE plant
No full textGas cleaning systems of MSW (Municipal Solid Waste) incinerators are characterised by the process employed to remove acid gases. The commonly used technologies for acid gas removal are: (1) dry treatment with Ca(OH)2 or (2) with NaHCO3, (3) semi-dry process with Ca(OH)2 and (4) wet scrubbing. In some recent plants beside a wet cleaning system, a dry neutralization with Ca(OH)2 is used. The goal is to reduce the amount of acid to be removed in the wet treatment and the liquid effluents produced. The influence of these different technologies on the electrical efficiency was investigated by a detailed simulation of a WTE (Waste To Energy) plant with a capacity of about 100,000 t/y of MSW. The effects of the different gas cleaning systems on electrical efficiency were significant. The difference of efficiency between the most advantageous technology, which is dry treatment with NaHCO3, and the least advantageous technology which is semi-dry treatment, is about 0.8%. A simple economic analysis showed that the few advantages of dry technologies can often be lost if the costs of chemicals and the disposal of products are considere
Operational analysis of natural gas combined cycle CHP plants: energy performance and pollutant emissions
Full text linkThe natural gas-fired combined cycle (NGCC) plants are among the best technologies for power production, especially when operating in combined heat and power (CHP) generation feeding a district heating (DH) network. Even if usually designed to operate with very high utilization factors, thus satisfying mainly the base load, nowadays these plants are often used also as backup power. This is due mainly to the necessity to compensate the nonprogrammable renewable energy sources (RES) production, and it can be done, thanks to the good flexibility of these plants. However, in off-design conditions, the energy performance and the pollutant emissions may not be as good as the expected nominal ones. In this paper, the real operation of three NGCC units has been analysed in detail by considering mean hourly data over several years. A gas turbine efficiency curve at partial loads has been obtained, showing a decrease of conversion efficiency at lower unit loads. The CO emissions during the start-up and shut-down procedures of the plant reached values that are some orders of magnitude higher than in normal operation. This criticality should not be forgotten when using these units for frequent on-off operations
Analysis of an LPG accidental release
No full textAn industrial LPG storage accident due to the release of propane from a tanker is described in this paper and the sequence of events that led to the collapse of a storage tank is examined using simulation software. A model taking both released flows into account as a radiant thermal contribution in the presence of flames is presented. The progression of the accident is assessed through digitalization and processing of the film of the fireball produced by about 500 L of LPG, whose diameter was calculated as approximately 50m
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