Thoroughly cleaned
In mid-2007 De Jong Thermal Engineering received an order from Theo Pouw Secundaire Grondstoffen in Utrecht to design and install two post-combustion (TNV) plants and several industrial gas burners for use at various points in the production process.
With the two production lines Theo Pouw Secundaire Grondstoffen processes contaminated soil and granular asphalt containing tar. The process gas released during the evaporation process contains a high level of combustible components. To convert these components into heat Theo Pouw Secundaire Grondstoffen has opted to install advanced post-combustion units combined with heat exchangers. These systems were installed in the first half of 2008 and delivery ready for operation took place at the end of 2008.
Theo Pouw Secundaire Grondstoffen is one of the few businesses in the Netherlands that have established a specialist process for this specific market segment. The process of purifying (concentrating) soil and granular asphalt containing tar is a continuous process. The process gas released is treated in various stages, each with its specific process conditions and properties. These specific process stages require specific installations, which have to be capable of performing their task reliably and optimally under all conditions: custom designs therefore.
The solution
The basis of conversion of the combustible components is formed by the post-combustion process, in which the ‘fuel’ is burned at a high temperature using air. The system of recuperative post-combustion has been chosen because of the characteristics of the process gas. At the same time extensive attention has been devoted to the rapid, efficient mixing of the gas and air flows, resulting in optimum conversion. The energy generated in this context (in the form of hot flue gases) is reclaimed by means of heat exchange and (partially) re-used within the primary process. The flue gases are odourless and contain no hydrocarbons. The flue gas undergoes further treatment in the downstream flue-gas scrubbing facility. The overall process consists of several linked sub-installations, including an evaporation drum and a dust drum, which are also equipped with client-specific, industrial burner systems from DJTE. Even under severe operating conditions, these burners are highly reliable and versatile. Here again environmental and business objectives have been balanced against each other.
Result
The installations supplied comply with the process and emission conditions established by the client.
Key figures for TNV
process gas flow | 15.000 Nm3/h @ ca. 400 °C |
exhaust temperature | 850 °C |
burner capacity | 10 MW (opstartvermogen) |
production cycle | 24 uur per dag / 7 dagen per week |
Soil decontamination | TAG-reiniging |