Previously, we discussed and demonstrated how plasma arc plasma gasification nearly eliminates dioxin formation, this entry looks to address semi-volatile heavy metal compounds and other air emissions.

The high temperatures at which the plasma-arc plasma gasification processes operate can result in the generation of volatile inorganic constituents (i.e. metals and metal oxides), sometimes at a higher level than compared to convention thermal treatment processes, particularly if the waste feedstock comes in direct contact with the very hot plasma-arc plasma gasification plume as these compounds may become volatilize and carried downstream with the syngas generated. While many are removed by the gas cleaning and conditioning systems, in plasma-arc plasma gasification processes where the off gases are not cooled (i.e. plasma combustion, which is not utilized by PEAT) these heavy metal compounds could be carried out in the stack gases, increasing the levels of potential contaminants that are emitted.

Downstream of any quench system or syngas cooler, any entrained particulate matter and/or acid gases (H2S, HCl, etc.) are scrubbed with water typically using either a packed-bed tower/Venturi scrubber or through a dry filtration system. Additional equipment in the form of HEPA or baghouse filters may also be utilized.

The results presented in the below reflect emissions from PEAT International plasma-arc plasma gasification waste-to-energy systems where the syngas was not utilized and ultimately processed in a thermal oxidizer or secondary reaction chamber.

Last week, we discussed and demonstrated how plasma-arc gasification nearly eliminates dioxin formation, this entry looks to address semi-volatile heavy metal compounds and other air emissions.

The high temperatures at which plasma gasification processes operate can result in the generation of volatile inorganic constituents (i.e. metals and metal oxides), sometimes at a higher level than compared to convention thermal treatment processes, particularly if the waste feedstock comes in direct contact with the very hot plasma gasification plume as these compounds may become volatized and carried downstream with the syngases generated. While many are removed by the gas cleaning and conditioning systems, in plasma gasification processes where the off gases are not cooled (i.e. plasma combustion, which is not utilized by PEAT) these heavy metal compounds could be carried out in the stack gases, increasing the levels of potential contaminants that are emitted.

Downstream of any quench system or syngas cooler, any entrained particulate matter and/or acid gases (H2S, HCl, etc.) are scrubbed with water typically using either a packed-bed tower/Venturi scrubber or through a dry filtration system. Additional equipment in the form of HEPA or baghouse filters may also be utilized.

The results presented in the below reflect emissions from PEAT International plasma gasification waste-to-energy systems where the syngas was not utilized and ultimately processed in a thermal oxidizer or secondary reaction chamber.

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A lot has been reported regarding the EPA going after GHG emissions, specifically CO2. Initially the thought was the EPA would just focus on the largest facilities (ones that release more than 25,000 tons per year), but it appears that this mandate may be expanded to other industries. Further while it appears this threshold may be increased (between 75-100,000 tpy – the EPA still intends to regulate at the 25,000 ton number – it just may give more time to those facilities to around 2013 possibly.

One in particular is the refineries, where the EPA may propose a new NSPS this summer that is expected to include GHG emissions.

One way a refinery can offset these emissions is using a PTDR system for industrial waste treatment whereabouts it could potentially reducing the carbon footprint associated with the industrial waste stream disposal process.

Carbon footprint reductions could be realized in the following areas:

• Elimination of transportation as waste would no longer travel hundreds of miles for treatment and/or storage leading to reductions in carbon dioxide (CO2), nitrous oxide (NOx) and methane (CH4) emissions

• Alternative waste-to-energy processing as waste would not longer be landfilled or incinerated leading to reductions in carbon dioxide, nitrous oxide and methane emissions

Further, when the syngas is consumed in gas engines as a fuel source (i.e. waste to energy), the emissions of the resulting flue gases are significantly lower than those generated by other methods such as landfilling and/or incineration.

PTDR facilities offer distinct advantages over conventional incinerator systems used for the thermal destruction of waste:

• High operating and uniform temperatures preventing the formation of furans and dioxins (no “cold spots” in a PTDR)

• A controlled processing atmosphere

• No fly or bottom ash generated, requiring further treatment and disposal

• A PTDR system produces a gas volume that is significantly less than the total combustion gas produced by an incinerator processing the same amount of waste

• The minimization of outside air used in the sealed pyrolysis process reduces the potential for emission control problems, particularly those associated with nitrous oxides and other pollutants.

PEAT International designs advanced waste to energy & resources systems. PEAT’s waste treatment plants converts waste into energy and other useful end products. Industrial Waste Treatment Plants, Hazardous Waste Treatment Plants, Toxic Waste Treatment Plants with Plasma Thermal Destruction Recovery (PTDR) Technology.