Database of Waste Management Technologies Life

Case Study 12 – Waste to Energy (WtE) with bubbling fluidized bed of SRF

 

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Name: Ecoenergia SRL-Corteolona (Pavia-ITALY) case study 12

Ecoenergia SRL Facility in Corteolona-Plant

Owner: Ecodeco S.r.l-A2A Group
Operator: Ecodeco S.r.l-A2A Group
Technology: WtE
Designed Capacity: 7,5 t/h equal to 60.000 t/year of RDF (equal to 120,000 t / year of MSW)
Cost: 35 million € (2003)
Location: Corteolona, Pavia, Italy
Served Area: -
Commercial Start Up: 2004
Contact Details
Address: Loc.Manzola Fornace
27014 Corteolona (Pavia),
Italy
Phone Number: +39 0382 727 609
Fax: -
Email: b.puglisi@ecodeco.it
Website: www.ecodeco.it

 

Short Description

The Ecoenergia SRL WtE plant is located in Corteolona of Pavia in Italy and has been in operation since 2004. The Plant has first designed to treat 7,5 t/h of Municipal Solid Waste Residual Fraction.

At the Plant the combustion and recovery sections are integrated to each other since furnace walls are of membrane design. In the following a short description of the system is provided.

System Description

In the bubbling fluidised bed boiler (BFB), combustion takes place in a bed consisting of bed material and fuel ash. The bed is held in suspension by an upward flow of combustion air. The air flow and velocity are chosen to give intense mixing of material with minimum of carry-over of particles out of the furnace. The combustion in the BFB takes place in the dense bottom bed except for the fines in the fuel which burn in a particle suspension above the bed.

To further enhance the combustion and reduce the emissions, the front, rear and side walls of the furnace are equipped with asymmetrically placed arches through which combustion air and re-circulated flue gas is introduced. The intense mixing allows the BFB to operate at low excess air levels.

Membrane wall construction provides a fully water-cooled and gas tight furnace enclosure.

To achieve the right bed temperature and to protect the lower part of the furnace from erosion and corrosion, the lower part of the walls are lined with refractory material (rammed or gunned refractory).

To ensure that the temperature of the flue gas is at least 850°C for at least two seconds after the last injection of combustion air, the major part of the upper furnace walls will be covered by refractory lining.

Primary air is fed to the boiler windbox below the furnace and up through the reactor bottom in a large number of aligned erosion resistant nozzles. The overfire air is supplied in several stages. Secondary, tertiary and cross air (side walls) is supplied through nozzles located above the fuel inlet on the front and rear wall to maintain a good penetration throughout the entire load range, The secondary and tertiary air nozzles are directed to promote circulation of bed material above dense bed.

Special flue gas swept plates are located below the fuel chutes in order to provide an increased distribution of the fuel into the combustion chamber.

Downstream furnace an empty pass cavity is installed. The empty pass ( radiation cavity) is made of membrane walls and it is designed to reduce the flue gas temperature prior to the superheaters to avoid sticky components from building up on the tubes. The radiation pass is divided in several parallel gas passes by vertical water cooled tube screens.

Flue gas coming from the empty cavity enters the rear convection pass enclosure. The rear convection path enclosure is of similar membrane wall design as that of the furnace. It contains orizontal exchange surfaces and in particular:

  • Superheater
  • Boiler bank
  • Economiser

Air Pollution Control System

The airpollution control system includes 2 cyclones in parallel and one bag house filter for the removal of particles (dust control) that achives more thatn 99.99% reduction. Moreover the unit is equipped with a semi dry type Scrubbing to conduct chemical gas cleaning. In addition NH3 in water solution is injected in the combustion section by means of compressed air distributing lances to remove NOx. NOx reduction is achieved by 55-60%. Activated carbon is used for Hg removal.

Treatment of the Produced Ash

  • Cyclones ash is treated on line. Cement, water and additives are injected directly in the ash extraction system which is installed on the bottom of the cyclones .Treated ash is discharged in closed container and disposed in the landfill which is available nearby the combustion plant.
  • Boiler ash is disposed in the landfill.
  • Bag house filter treated by external authorized plants.
  • Bottom ash undergoes metal separation (ferrous and non ferrous), sand recovery and recirculation in the fluidized bed.

 

Key Facts

Treatment Capacity: 64,526 tpa (Data of the year 2009)
Input Material: Municipal Solid Waste Residual Fraction 63,929 tpa
Filter-pressed biological sludge 597 tpa
Output Products: Boiler ash 2,536 tpa
Cyclones ash 4,925 tpa
Bag house filter ash 2,129 tpa
Bottom ash 3,334 tpa
Electric production 63 million kWh (2009)
Flue gases 10,300 Nm3/tons iput (84,685 Nmc/h) (2009)

 

Extra Information

Operational Data
Combustion temperature 950-1050 oC
Maximum diameter of material in reactor 150mm
Air supply air: exhaust gases ratio 11% O2
Steam parameters 400 oC (temperature)
40 bar (pressure)
Air Emissions (mean daily values at, T=273,15 oK, P=101.3 kPa & O2=11%)
TSP 0.3 mg/m3
TOC 0.7 mg/m3
HCl 3.6 mg/m3
HF 0.04 mg/m3
SO2 1.8 mg/m3
NOx 172.9 mg/m3
CO 6.9 mg/m3
CO2 0.180 Kg/m3 (9.1% VOL)
Amount of flue gases 10,300 Nm3/tons iput (84,685 Nmc/h)
Temperature of gases 148 oC