Amongst other products, sandwich boards are manufactured from glass-fibre reinforced plastics (GRP). During the production process, styrene emissions are released from the processed resins. These are collected in the exhaust air from the various production areas and must be cleaned in compliance with the 31st Federal Emission Control Act.

Challenge

• Simultaneous low, medium and high solvent concentrations in various exhaust air flows
• High heat demand by emitting system and in the production halls
• Control and monitoring of the LEL according to safety requirements of the EN13849
• Integrated solution for intake of supply air, collection of exhaust air, movement of exhaust air and cleaning of exhaust air is necessary because this is a new system
• Continuous expansion of production

Solution

• Enrichment of the exhaust air with low styrene concentrations and low temperatures in one enrichment pipe, enrichment rate 1 : 8
• Regenerative thermal oxidiser (RTO) for the enriched exhaust air flow and the exhaust air with medium and high styrene concentrations and medium temperatures
• Heat recovery for heating hot water in the hot bypass of the RTO
• Heat recovery in the clean gas for heating the hall supply air
• Redundant LEL monitoring

Period

• 1st system: Commissioned August 2006
• 2nd system: Commissioned April 2008
• 3rd system: Commissioned October 2008
• 4th system: Commissioned December 2014

Facts about the project

• Volume flow of the exhaust air to the respective enrichment 30,000 Nm³/h, 65,000 Nm³/h, 65,000 Nm³/h and 55,000 Nm³/h
• Volume flow of the exhaust air directly to the respective RTO 10,000 Nm³/h, 15,000 Nm³/h, 0 Nm³/h und 15,000 Nm³/h
• Solvent concentration of the exhaust air to the enrichment 650 mg/Nm³ and directly to the RTO 8 g/Nm³
• Temperature of the exhaust air to the enrichment 30°C and directly to the RTO 40 °C
• Solvent styrene and acetone