System controls styrene emissions

Citation

(1998), "System controls styrene emissions", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 6. https://doi.org/10.1108/aeat.1998.12770fab.007

System controls styrene emissions

System controls styrene emissions

Keywords Emissions, Environmental regulations, Pera, Styrene

A two-year European development programme, co-ordinated by Pera in the UK, has culminated recently in the introduction of an innovative system for the control of styrene emissions produced during the manufacture of glass fibre reinforced polyester (GRP) components and products (see Figure 1). The distinctive smell of styrene will be a familiar one to anybody who has experienced GRP moulding in action.

The imminent enforcement of tougher health and safety and environmental legislation throughout the European Union, designed to restrict styrene emission levels, prompted the need for the new system which is aimed at GRP moulders of all sizes. A voluntary code of practice currently restricts the workplace exposure level to 50ppm but some EU member states have set a 20ppm level, so many moulders run a real risk of prosecution, especially as future legislation may be even stricter.

Larger manufacturers with higher materials consumption and therefore potentially greater workplace and atmospheric emissions, are likely to be the first to be targeted under tighter legislation and could be the first to benefit from the system.

There are also many small and medium-sized companies which use open moulds in conjunction with traditional spray and hand lay-up techniques which could become liable to prosecution. These traditional methods result in high levels of styrene being emitted during both the lay-up and resin curing stages, increasing exposure in the workplace and creating a potential health risk which has hitherto been largely ignored.

The use of alternative production systems and materials, such as resin transfer moulding and low styrene emission resins, can cut emissions but these are relatively expensive and are not suited to all applications.

Figure 1 Description of operating principles

A prototype of the new system has been in successful operation at a GRP manufacturing company, which is said to have demonstrated cost-effective running and high performance levels (Plate 6). Plans are well advanced for commercial production of the system.

The two-stage system is based on the use of a special regenerative adsorption media, followed by a catalytic oxidation section. In its adsorption mode, extract air from the workshop is passed into an adsorption bed and the cleaned air discharged to atmosphere or returned to the workshop to minimise heat losses. Following an adsorption period, typically 10-12 hours, the system is switched to regeneration mode. In this mode a heater generates a hot air flow which maintains the catalytic oxidation section at its operating temperature. By recycling a proportion of this hot air, the temperature of the adsorption bed is raised and the styrene carefully desorbed, typically over 6-8 hours. This means that the process can take place overnight so that the system is ready for the following day's production. The desorbed styrene passes through the catalytic oxidation section where it is oxidised to water and carbon dioxide.

Styrene discharge levels from the system on both adsorption and regeneration are reported to be significantly lower than current or anticipated future European legislative levels.

A consortium comprising 11 organisations was involved in the system's two-year development programme, which was established under the European Commission Craft initiative, co-ordinated in the UK by Pera at its Technology Centre in Melton Mowbray (Leicestershire), with the University of Newcastle as the second research centre, specialising in the development of the adsorption media. Selected to provide a balance of complementary technical expertise and end-user experience, the other partners are: Fibrecast, Klargester, Northern Plastics, PICA, Camfil, AirProtekt, Reichhold, ETA, Matrasur, NCRL and Tolsa.

Plate 6 The prototype of the new system

Further details are available from Pera. Tel: +44 (0) 1664 501501 (UK); or Matrasur. Tel: +33 1 69 19 17 10 (France).