| 摘要 |
<p>A gaseous stream comprising nitrogen and solvent vapor istaken from a curing oven (not shown), is passed through preliminary heat exchangers 13 and 23, and enters a first heat exchanger 33 through conduit 30. Remaining vapor is condensed in the heat exchanger 33 by heat exchange with chilled medium entering the heat exchanger from conduit 52 and leaving via conduit 37. The medium then enters a second heat exchanger 43 via conduit 42 where it is chilled by liquid nitrogen supplied via conduit 47, the chilled medium being recycled to the first heat exchanger. The resulting vaporised nitrogen is supplied to form gas curtains at the entrance and/or exit of the oven. This nitrogen leaving the first heat exchanger 33 is used to supply a return stream to the interior of the oven at a rate that substantially matches that at which nitrogen is withdrawn from the oven. This enables a mass balance to be maintained in the oven atmosphere.</p> |
