Via Raibano 32, Coriano (RN)
The waste-to-energy plant is located at Via Raibano 32 in Coriano, in the province of Rimini. It has been operating since 1976, and began with two incineration lines, to then increase to three incineration lines in the definitive configuration in 1991, equipped with an energy recovery system.
The plant remained unchanged until 2008, when the old lines 1 and 2 were dismantled, and construction began on the new line 4, which began operating halfway through 2010.
During the transition phase, only line 3 remained operating; it was then shut down in the second half of 2010 for a planned upgrade to update its technology to that of the new line 4, equipped with an energy recovery system.
Aside from waste recovery (R1), the plant is authorised for recovery (R12) inside the pit. For this last activity, the total maximum quantity of waste sent to other destinations, including outside the province, is 30,000 metric tonnes per year.
The maximum quantity of waste authorised for incineration is 150,000 metric tonnes per year.
Page updated 26 August 2015
Environmental compatibility with current regulations (Legislative Decree 152/06)
The waste-to-energy plant makes it possible to dispose of a variety of waste through combustion. The heat this generates is exploited to produce heat and electricity.
1 - Waste receipt and storage.
The plant is equipped with a storage pit completely made of waterproofed reinforced concrete, which is 8.5 m deep. The waste is moved and the incinerators are loaded with hydraulic buckets connected to two bridge cranes found at the top of the building.
2 - Combustion.
The plant is equipped with a water-cooled moving grate incinerator, which is able to incinerate up to 16 metric tonnes of waste per hour with a lower calorific value of 2,500 kcal/kg. The alternating movement of the rungs of the moving grate ensures that while the waste progresses to the combustion chamber, it is mixed to facilitate combustion and decrease the amount of uncombusted materials in the remaining slag. The air needed for the incineration process enters the combustion chamber through the grate (primary air) and through the openings located on the side walls (secondary air). The primary air is suctioned from within the waste storage pit in order to keep the pit in a vacuum, thereby preventing the spread of odours to the outside air. In addition, to increase energy efficiency, before the primary air enters the combustion chamber it is pre-heated through heat exchangers which use the steam generated by the boiler. To ensure that combustion is complete, the residues are then conveyed to the post-combustion chamber, the size of which ensures that fumes remain at a temperature above 850°C for at least two seconds. Two methane-fuelled support burners which turn on automatically based on the fume temperature ensure that this temperature is maintained, even if there is waste with a low calorific value. Also in the post-combustion chamber, the first fume purification phase is carried out with the injection of an ammonia solution for nitrogen oxide abatement (selective non-catalytic reduction process - SNCR).Once the slag from the combustion reaches the end of the grate, it falls into a tank of water to ensure it is no longer burning, and is subsequently transferred to the storage pit by way of extraction and transport systems.
3 - Steam generation.
To produce electricity, after the fumes generated by combustion have passed through the post-combustion chamber, they are sent to a heat recovery boiler (steam generator) which produces superheated steam at a pressure of 47 bar and a temperature of 400°C. The water-tube boiler has the dual function of recovering the heat contained in the fumes and cooling them for the subsequent purification phases. The fumes enter the boiler at approximately 950-1,000°C and exit at approximately 180°C, to then be sent for purification.
4 - Fume purification.
The line is equipped with a completely dry fume treatment system, consisting of different devices placed in succession for each line: a first purification stage with the abatement of the solid particulate in the bag filter which uses hydrated lime and active carbon as reagents, and a second stage entailing the injection of reagents such as sodium bicarbonate and active carbon, with an additional passing of the fumes through the bag filter for solid particulate abatement and a final section for the further reduction of NOx with a catalytic system (SCR) through the injection of an ammonia solution.
5 - Cogeneration of electricity and heat.
The superheated steam generated by the boiler is transformed into electricity by a turbine with nominal electric power of 10.5 MW. Part of the steam injected into the turbine is used to fuel the sludge drying plant. The project entails installing an exchanger which, in a second phase, will be connected to a district heating network serving Coriano´s manufacturing industry.
The plant is equipped with a Continuous Emissions Monitoring System (CEMS) which has automatic analysers functioning 24 hours per day to continuously monitor the quality of atmospheric emissions.
A suitably heated sample probe continuously transports a sample of the gas from the plant´s chimney to the analysis booth where the instrumentation is installed. The sample is put into the Fourier transform infrared spectroscopy (FTIR) analyser, which continuously detects the absorption spectra of the compounds to be measured. A mathematical process is used to compare the spectra with the typical spectra of the substances being investigated. The comparison makes it possible to determine the quantitative values (concentrations) of the elements and compounds analysed. Besides the FTIR system, there are other continuous analysers and meters needed to complete the fume analysis by determining other parameters such as: particles, organic compounds, mercury, oxygen, temperature, flow and pressure.
A data acquisition system (SADE) also continuously provides the values obtained by calculating the half-hourly and daily averages of the concentrations measured, which are compared with the maximum admissible limit values set by the Control Bodies. These data are also provided on the group´s website, where they are automatically updated every half hour.