Taming Volatility

The abatement of volatile organic compound (VOC) emissions is compulsory in most global regions today, with corporate, international and regional legislative drivers in place, and action triggered by the quantity of solvents and types that a process uses. Emission limits may vary according to regional legislation, although the use of chlorinated and risk phrase compounds (R40, R45, R46, R49, R60 and R61) generally demand more stringent abatement criteria.

The selection of an abatement solution often involves the review of a number of options, involving iterations considering criteria such as VOC removal efficiency, energy use, off gas generation, sensitivity to solvent types, future process changes, as well as ensuring the selection satisfies best available technology (BAT), a key requirement of legislation.

In the pharmaceutical manufacturing sector, dealing with emissions from a variety of sources is commonplace, whether it be from a primary manufacturing process, such as bulk reactor emissions with small flows of highly intermittent, concentrated, often nitrogen-blanketed emissions, or from secondary operations such as tablet coating and packaging, where flows are generally in air, have larger volumes, with insolvent air concentrations in the range of 1 to 25 per cent lower explosive limit (LEL) and emitting hours being in the thousands per annum. It is one of these secondary processes of tablet coating that will be discussed here.

TABLET COATING OPERATIONS

If we take a tablet coating operation, the solvents used may carry fillers and coating compounds applied to achieve specific medication release characteristics, as well as either using single or multiple solvents throughout the coating process. Gathering data on solvent type, use and process conditions is key to achieving a refined abatement solution that will not affect the process or overburden costs of operation.