4.2. Estimation of fugitive emissions and process area
Fugitive emissions from the six MMA production routes are quantified using the simple PFD-based estimation method (Hassim et al., in press and Hassim and Hurme, 2008). The emission rate calculation based on simple PFDs utilizes precalculated standard submodules representing subprocesses in the route (Table 3). Example of standard module determination is shown in Fig. 3 for the first subprocess of the C2/PA route. This subprocess comprises of the following submodules: tubular reactor, compressor, flash system, and distillation. Since exact mass balance data is still unavailable at this earliest design stage, the most toxic chemical in each process stream is determined to represent the stream emission rate. Fugitive emissions of each substance throughout the route are added up. Also the process areas are estimated based on the number of standard modules involved in the route. The estimated fugitive emissions and process areas are summarized in Table 4.