BENCHMARK PERFORMANCES FOR AUTO SCRAP SHREDDING FUME TREATMENT (VOC)

A new, Danieli-patented system for gas cleaning and controlling Volatile Organic Compound (VOC) emissions was commissioned successfully this year.
The innovative solution achieved all project targets, with total VOC emissions lower than 5 mg/Nm3, proving this new technology position as the new benchmark for dedusting systems for automotive recycling.
The shredder at RMB treats a mixed feedstock of scrap, including compacted vehicles; for this reason the fume-treatment plant was required to treat volatile organic compounds (VOC).

 

It should be noted that the abatement of VOC has only recently become mandatory  in the car recycling industry, and this requirement involves other pollutants, too. One suitable technology for VOC control is oxidation at high temperatures. However, this method was not economically viable in this case as VOC concentration is so low that it cannot support the self-combustion of VOC. As a result, external fuel must be used to increase the fume temperature to approximately 900°C.

Due to the risk of water vapour condensation from the pretreatment stage involving a wet scrubber (which is necessary for dust abatement), it is not possible to treat the air directly with a bed of activated carbon, and dry pre-treatment with a bag filter is not feasible due to the potential fire hazard caused by flying burning materials, which must be quenched with water sprayed in the scrubber.

The Danieli technology involves controlling VOC with a bed of activated carbon and processing the primary air flow from the shredder, together with a secondary flow coming from air separation equipment installed at the fluff separator. The primary fumes are dedusted with a cyclone and then with a wet scrubber, while the secondary flow is pre-filtered with a bag filter and heated by an external fuel burner prior to mixing with the primary air flow (from the shredder). The temperature of the mixed flow is higher than ambient temperature, thus preventing the risk of condensation in the carbon bed. The advantage of this technology is that a free flame can be safely used to heat only the secondary flow of air, which does not contain VOC.

The flow rate of air treated by the activated carbon bed does not increase significantly, because the secondary flow is only around one fifth of the primary flow. The combination of the two lines (primary flow from the shredder and secondary flow from air separation unit) is economically advantageous because it allows using only one induced draft fan and one stack instead of the two which would be required with two independent lines.

The project was successful and all targets have been reached, with total volatile organic compounds lower than 5 mg/Nm3. Due to the innovative solution this technology will become the new benchmark for dedusting systems for the car recycling industry.

RMB shredder DCR 1827 - 2000 HP

RMB shredder DCR 1827 – 2000 HP

RMB plant

Shredding plant

Target values of the fume treatment plant, espresse as pollutants at chimney, compared with the measured values

Coordonnées

Danieli. Plants and equipment for the steel industry

Danieli Team mission is to serve Customers with competitive plant and process technology/automation to produce quality at the lowest depreciation and production cash costs and offer efficient after-sale service. The technology spectrum and relevant process know-how provided by our Product Lines, the well-known tendency towards innovation and high reliability are the best guarantees in reaching this target.

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