Regenerative Thermal Combustors
Regenerative thermal combustors – CORAL Engineering, Milano
The CTR Regenerative Thermal Combustors are used for the removal of Volatile Organic Compounds (VOCs) present in air flow extracted from production departments.
The combustion of VOCs occurs in a thermally insulated chamber at a temperature of 750-800°C, TOC output values in the order of 5-20 mg / Nm3can be obtained. The heat required is supplied by fuel, usually natural gas or LPG.
The Regenerative Thermal combustors owe the adjective "regenerative" to the fact that the heat of exhaust smoke from the combustion chamber is transferred to the ceramic mass contained in a first heat exchange tower; the incoming fumes, already warm, pass through a second exchange tower and receive the heat accumulated and supplied by the outgoing fumes. A third room in stand-by ensures that there are no polluting fluctuations coming out of the stack during the inversion phase of the rooms.
The design criteria is defined by what is stated in prospectus 1 "Minimum requirements for thermal and catalytic combustion systems" UNI 11304-2: 2008 regulation, implemented in PC.T: 02 profile of BAT Lombardia (Regional Council Resolution 30 May 2012 - no. 3552), in particular:
- Calculated lenght of time that the smoke remains in the burner zone between the masses of the two towers in the absence of chlorinated VOCs: t> 0.6 s
- Minimum operating temperature ≈ 750° C in the absence of chlorinated volatile organic compounds VOCs.
The Regenerative Thermal combustors can be of various types:
- Bicameral: have two heat exchange towers, at the time of the inversion of the IN / OUT cycle there is a moment in which the fumes do not pass through the combustion chamber and so there is an emission peak in the funnel. This drawback can be obviated by inserting a compensation chamber where to store fumes at the time of chamber reversal.
- Three-compartments: Have three recovery towers, the third tower, in stand-by, allows to send purified fumes to the stake, in the combustion chamber.
When to use the CTR Regenerative Thermal Combustor:
- Processing (and emission) continuous cycle for 24h, and at least 5 days a week.
- The concentration of the polluting volatile organic compounds VOCs is high (even in the order of 1-2 g / Nm3) and flow rates are low.
- Flow of powder less than 5 mg / m3 and a flammable VOC content lower than 25% at LEL point (lower explosion limit). Also if there are organic substances in the form of steam at emission time and condensable at room temperature, they must be separated with appropriate inertial filters and cyclones.
- It is possible to pre-treat the emissions in order to reduce the dust content: it is possible to have coalescing or scrubber systems.
- You may need the protection of the suction lines and combustor with suitable ATEX protection systems.
- INLET fumes temperature: it depends on the type of dust separator system.
- Fuel consumption: on 10,000 Nm3 / h existing systems consumption will be 18 - 22 Nm3/ H of methane gas, standard use, with no pollutant.
- Combustion temperature 750-800° C
- OUTLET fumes temperature: ≈ 80-100° C higher than the inlet temperature.