ISOTHERM PWR® - An innovative technology which secures high

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The Technology


ISOTHERM PWR® - An innovative technology which secures high



The flameless combustion performs low emission and high efficiency energy recovery from brown fuels. It has been extensively tested with hazardous residues (petrochemical, pharmaceutical industries, etc.), as well as conventional low rank fuels like coal, shale oil, biomass, etc.

The innovative process proposedshows an ensemble of benefits which make it unique on the waste disposal and energy market. ISOTHERM PWR® process is extremely flexible both in terms of waste/fuel composition and fuel feed rangeability.

In stationary conditions, reactor outlet stream is quenched by a quota of recycling gas, so that the mixed stream enter a pressurized heat recovery fire?tube steam generator. The flue gases, which are mainly constituted of CO2 and H2O, exit the boiler at a temperature of about 250?300°C. The reactor outlet temperature is in the range 1550?1700°C. A flue gas quota (called long recycling line) is addressed into the reaction chamber in order to control the reaction temperature, while another flue gas quota (short recycling line) is redirected towards the reactor outlet and it is mixed with the reactor outlet flow in order to get a mixture temperature in the range 650?750°C.

A third quota of the flue gas is expanded in a chocked valve to the ambient pressure. The fume post treatment and dry acidic compound neutralization takes place in a socket filter.

The industrial waste treatment occurs in a reactor where a very fast oxidation reaction between waste and pure oxygen takes place at temperatures in the range of 1350-1450°C (temperature of the reactor inner wall) and pressure of 4 bar absolute. Oxy combustion occurs in the presence of a high concentration of triatomic gases such as water and carbon dioxide (they represent 90% of the flue gases) which are opaque to infrared radiation. The high concentration of these gases allows the transmission of the heat of reaction, inside the reactor, to occur mainly by radiation. The temperature in the reactor is, in this way, almost high and uniform, therefore the process is called Isotherm.

Thanks to both the uniform temperature (1350–1450°C – measured by the optical pyrometers) in the whole reaction chamber and the flameless combustion, we obtain:

$11)      all the combustible organic compounds are transformed into simple and inert compounds such as carbon dioxide and water, with no toxic by-products such as Dioxins, Furans, Polyaromatic hydrocarbons

$12)      the resulting ashes melt and settle on the bottom of the reactor (they are produced solely by the incombustible substances contained in the industrial waste).

The vitrified beads form the so-called “slag” which is vitreous and inert. If heavy metals should be present in the waste, they will be encapsulated in the slag with the other incombustible substances, without being released in the environment.

This feature is typical of the so-called flameless combustion.

More specifically, we drive the attention on the following peculiarities of the innovative process:

$1          high Temperature Pressurized Oxy-Combustion;

$1          compact hardware per unit power;

$1          reactor is tailored to process, irrespective of burner requirements;

$1          combustion reaction takes place over the whole combustor volume;

$1          the high concentration of Infrared-opaque tri-atomic molecules (CO2, Water) secure the very fast, gas-to-gas, heat transfer by irradiation;

$1          the process is completely controlled by DCS, distributed control system ;

$1          the combustion design is focused on the process, no longer on flame pattern;

$1          minimal flue gas post-treatment: neutralization only;

$1          high yield heat recovery, 100% at high energy level;

$1          fly ashes are quantitatively segregated under the form of molten vitreous zero carbon slags.


Markets Addressed


Coal Related

Waste- to-energy related

Combustion technology for waste-to-energy and efficiency energy recovery from different fuel market

Water treatment equipment and waste disposal systems

Energy recovery from biomass, waste, etc.


Stage of development

Development Phase

Comments: None

Intelectual Property status

Pantent(s) applied for but not yet granted

Comments: None