Treatment Systems

Regenerative Thermal Oxidizer (RETOX)

VOC: Common Problem in Industrial Plants

Volatile organic compounds (VOC) which are one of the main components used in many industrial process suddenly evaporates when contacted with the air and causes serious health effects and adverse environmental effects.

Although there are several definitions for VOCs, which are one of the main components in many industrial processes, they can simply be defined as organic chemicals that suddenly evaporate when contacted with the air even at room temperatures. In literature, European Union defines VOC as any organic compound having at 293,15 K 20 oC)a vapour pressure of 0,01 kPa or more.

VOCs may result from different activities including thermal processes, use of organic solvent in production processes, transport and handling of liquid fuels and organic compounds such us petrol and its derivatives, refineries and organic chemical industries. In general, all industries using solvents and organic petrochemical products cause VOC emissions.

Inside a processing plant, there are two main locations which can be a VOC emission source. The first one is the process activities itself inside the mixers, storage tanks and so on. Since these are considered as point sources, determination of the VOC emission is relatively easy. A piping system shall be placed into these sources in order to collect the VOCs and send them to the treatment unit. The second source is the fugitive emissions from the process equipment leaks. These fugitive emission sources include emissions during the transportation of the chemicals/solvents within the plant. Therefore, these cannot be point sources and directly increases indoor VOC concentration. Hence, in order for the treatment of those VOCs, a good air ventilation is required inside the plant.
Considering that many industries are using solvent based raw materials or petrochemical compounds in their production, VOC emissions is a common problem for most of the industry sectors. The main industries facing this problem are:
  • Paint industry,
  • Solvent producers,
  • PET and PET film manufacturers,
  • Packing industry,
  • Printing & lamination,
  • Chemical processing,
  • Aluminum extrusion painting,
  • Can/coil coating,
  • Pharmaceutical product manufacturers,,
  • Metal finishing & recycling,
  • Plastic finishing & recycling,
  • Surface cleaning production

Reduce Your Operation Cost with Proper Selection of the Technology!

The selection of the technology is a very important step in VOC abatement since the selection of the applicable technology will affect the operation cost of the system.

In adsorption technology, all the process is physical rather than the chemical which results as a limited performance when compared with the other technologies and it is not suitable for all kinds of pollutants. The initial cost of the system is very low; on the other hand the constant requirement of the activated carbon increases the operation costs.

Thermal oxidation systems depend on the chemical oxidation of the compounds and convert the VOC’s to CO2and H2O at very high temperatures (about 850 oC). The destruction efficiency of this technology is very high whereas the fuel consumption is also very high.

Santes provides a cost effective solution with high destruction efficiency having low fuel consumption called RETOX.

VOC Abatement Technologies:

Adsorption     Thermal Oxidation   RETOX
Heat Recovery - - +
Recovery Type - - Packed Bed
Heat Recovery Efficiency (%) - - 95
Stack Temperature 30-100 oC 850 oC 70-150 oC
Maximum DRE (%) 40 98-99.99+ 95-99+
Operation Cost Average High Low

 

Comparison of VOC Abatement Technologies for Different Parameters:

rto_tablosu-01

Santes provides a cost effective solution with high destruction efficiency having low or no fuel consumption called RETOX.

In an RETOX system a ceramic packed bed stores heat from hot gases coming from the combustion chamber while another ceramic packed bed releases heat into the cold gases flowing into the combustion chamber. A burner using natural gas or diesel as fuel maintains the temperature of the combustion chamber between 750 – 850 °C as required. The combustion chamber residence time is 1 second for the complete destruction of VOCs.

The inside of the combustion chamber is lined with a special insulation material having high insulation property to keep the heat losses to a minimum. The outside of the combustion chamber is covered with carbon steel. The inside temperature of the combustion chamber is measured with a thermocouple which is connected to automatic control unit. By means of thermocouple and continuous measurement of the inside temperature, the continuity of the combustion is enabled and guaranteed.

rto-01

A stream cycle time of 60 seconds is utilized. At the same time, the temperature of the ceramic beds is measured in order to optimize the cycle time. The heat recovery efficiency of the RETOX is estimated above 95%.

RETOX can typically work auto thermally with solvent concentrations above 2 – 3 g/m3. At waste air volumes of up to 100.000 Nm3/h, the installations achieve emission values of <20 mg C/Nm3 (half hourly mean value). The thermal energy of the outgoing air of the waste gas treatment system is utilized for warming up of the crude gas by alternating the heat transfer beds. With concentrations of 4 – 6 g/m3 the excess heat can be recovered and, for example, used in production processes.

RETOX technique is commonly applied to an airflow in the range of 1.500 - 70.000 Nm3/h for one dual bed unit. For flows >70000 Nm3/h, multi-bed systems are more economic. The maximum inlet temperature is 400 ºC. The maximum VOC inlet concentration will be limited by a 25 % LEL value for safety reasons, typically 12 g/m3.

Advantages of Santes RETOX Systems:

  • No fuel consumption when there are enough VOC in the stream,
  • Very high removal efficiencies of 99+%,
  • Lowest possible operating costs,
  • Minimal maintenance requirements,
  • Low electricity consumption due to special heat recovery media,
  • High thermal recovery efficiency up to 95%,
  • Cost effective design and low capital cost,
  • Ability to design and manufacture 2 can and 3 can systems,
  • Operator friendly solution with PLC integrated system
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