The pilot plant, supplied by Metener Ltd. (Finland), was located
at the Mustankorkea landfill in Jyväskylä in Central Finland. The
pilot upgrading facility contained an absorption column (500 l,
height 185 cm, diameter 60 cm), desorption column (500 l, height
155 cm, diameter 65 cm), closed water storage tank (volume
500 l) with a membrane expansion system maintaining water
feed-in pressure for a high pressure pump and gas drying unit
(Fig. 1). Both absorption and desorption columns were packed
with pall-ring (4 4 cm) filling material for high internal surface
area. A more detailed system description can be found in Rasi
et al. [8]. Contrary to that study Rasi et al. [8], in the present
set-up absorbent water was recycled back to the process after
desorption. The drying unit was a Bauer Kompressoren Securus
standard drying cartridge for pressurized gases, eliminating
odours, oil removal and drying (filling material weight 2098 g, order
number 060036). Filling material included activated carbon
and other (information not available) compound for removing
moisture. The volume of the drying unit was 2.85 l. These units
are widely used natural gas filling stations to lower the dew point
of the gas. The drying unit was operated at the same pressure as
the absorption vessel. The desorption vessel had a 0.3 bar of under
pressure relative to atmospheric pressure and this was maintained
with a pump.