REMOVAL OF VOLATILE ORGAN COMPOUNDS (VOC) THROUGH FILTRATION, CONCENTRATION AND COMBUSTION WITH REGENERATIVE HEAT RECOVERY
1. Type of technology
Adsorption on activated carbon or zeolites, followed by desorption with hot air or thermal oxidation of the desorbed substance with regenerative heat recovery.
2. Contaminants which can be removed
Volatile organic compounds of any type with boiling point below 160 °C and inlet concentration range between 0 and 1000 mg/Nm3.
3. Emission limits possible
Overall collection efficiency lying between 90 e 99%. Emission limits lower than 20 mg/Nm3 of TOC (total organic carbon).
4. Description of the technical solution
A new concentration and combustion system with regenerative heat recovery
Amboso has developed a fully automatic plant based on a concentration system for emissions through adsorption of the VOC on activated carbon and subsequent regeneration through heating, and desorption with hot air and combustion of the organic substances in a incinerator with regenerative heat recovery. With reference to the enclosed diagram: in this system the VOC-laden air is first filtered in collectors for the removal of any suspended solid particles, then it flows with motion from bottom towards top through filter units arranged in parallel, divided into various sectors and packed with adsorbent material. On flowing through these sectors, the organic substances are captured by the adsorbent material and the air, cleaned well below the regulatory emission limits, is discharged into the atmosphere. During the adsorption phase, such sectors are regenerated one-at-time with the heated atmospheric air in a direct hot air generator with natural gas burner (burner 2). The so-heated air flows through the sector of filtering units concerned with regeneration on a reversed flow basis (opposite to the adsorption flow, from top towards bottom). The hot air, on flowing through the bed of adsorbent material, heats it and causes the organic substances captured inside the pores to evaporate (desorb). After desorbing the air and organic substanced with a gaseous flow about 10 ÷50 times lower overall than that in the adsorption phase, they are thermally oxidized in a thermal type incinerator with heat recovery type i.e.: in which the contaminating organic compounds are converted, by effect of the temperature and oxidation reaction with the oxygen in the air, into carbon dioxide and water, with efficiency over 99%. The process achieves the highly important result of reducing by 30 to 40 times (depending on the initial concentration) the volume of gas to be incinerated, likewise increasing the concentration of VOC contained in the gas; in this way thermal oxidation of the VOCs does not require any type of auxiliary fuel, because the heat that is generated by flameless oxidation of the organic substances contained in the desorbed gas is sufficient to hold the minimum combustion temperature. The natural gas burner (burner 1) is only used to start-up the plant for the time strictly necessary to bring the ceramic masses to the work temperature (from 15 to 30 minutes). The reconcentrator on activated carbon is a treatment unit of very compact size, fully preassembled and ready for use, complete with control panel, PLC and supervisory computer for constant and continuous monitoring of the operating data.