Project GREEN SITE
“Supercritical fluid technologies for
river and sea dredge sediment
remediation”
Ing. Ruggero Corazza – ALLES S.p.A.
remediation”
– LIFE 10 ENV/IT/343 –
Definition:
Super-critical state: in conditions over theircritical temperature and pressure, fluids andtheir behaviours become partly like liquids(p.e. density) and partly like gas (p.e.propagation).Water and Carbon dioxide, in supercritical
What’s a supercritical fluid
Water and Carbon dioxide, in supercriticalconditions, are able to dissolve organiccompounds.
Sub-critical state: in conditions of temperatureand/or pressure a little below its critical ones,only some properties of a supercritical fluidhave been acquired.
Inlet: Polluted sediment, H2O, CO2
Outlet: H2O, CO2 , pollutants and
cleaned sediment
Process Temperature 250°C
Process Pressure 300 bar
1st Phase: Extraction of the pollutants
using supercritical CO2 and subcritical H2O
Process Pressure 300 bar
CO2 has Tcritical 31°C, Pcritical71 bar
H2O has Tcritical 374°C, Pcritical220 bar
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Inlet: H2O + Pollutants extracted
in Phase 1, air 300 bar
Outlet: CO2, H2O and salts, heat
Process Temperature 800°C
2nd Phase: Supercritical Oxidation of the pollutants
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Process Temperature 800°C
Process Pressure 300 bar
Extraction Reactor (left), Oxidation Reactor (right)
• Over 90% abatement of organic solvents.
• Over 95% abatement of washing liquor.
• Extraction times for the target compounds: 60’ – 90’ (max 5kg)
Oxidation times of 1 l of the target compounds: 1’ – 5’
• Absence of any residual solvents and micro-organisms in the dredged
Project targets
• Absence of any residual solvents and micro-organisms in the dredged
sediments.
Layout of the plant (Extraction + Oxidation)
Green Site’s plant front view
Green Site’s plant back and side view
Extraction layout during a test
Fase di Estrazione: Esecuzione
During the testing activity 2 kinds of samples have been used with 2 differentconcentration levels of contaminants: one with 50mg/kg and one with100mg/kg.
For each test about 2 kg of sediments have been treated.
Carbon Dioxide, used for extraction, has been re-used every time, while the
Extraction phase: test running
Carbon Dioxide, used for extraction, has been re-used every time, while the
liquid phase exiting from the separators has been collected and analized.
Oxidation layout during a test
Oxidation tests have been carried out introducing, at first, a liquid mixture ofwater and isopropyl alcohol to bring the reactor to the optimum processconditions; then, the first mixture has been replaced by a mixture of waterand hydrocarbons (polluttants)
Oxidation phase: inlets
For the oxidation tests we’ve used a mixture of water and aboput 7% ofhydrocarbons, in fact we wanted to verify the oxidation reaction using as fule,only hydrocarbons. So, we needed to concentrate the liquid phase obtainedfrom the extraction tests separing some cleaned water from the moreconcentrated mixture. In case of an industrial scale plant, for thisconcentration, we are thinking about a system based on a union of floatingsystems and filtration on membrane.
The performed oxidation tests have shown the ignition of an hydrotermal
Oxidation phase: test running
The performed oxidation tests have shown the ignition of an hydrotermalflame at the expected conditions (400°C and 300 bar) and its stablemaintenance (about at 800°C and 300 bar) both with the water and isopropylalcohol mixture and with the water and hydrocarbons mixture.
THANK YOU FOR YOUR
KIND ATTENTIONFor other informations:
www.green-site.netwww.alles.it
e-mail [email protected]