| 摘要 |
The EPA Cluster Rules for cellulose pulp mills are complied with by first collecting foul condensate including hazardous air pollutants (HAPs), such as methanol, at a temperature of between about 140-180° F., and passing the foul condensate into direct contact with heated vapor at a plurality of series connected stations to gradually heat the foul condensate to a temperature desirable for steam stripping. Then the heated foul condensate is steam stripped to produce a high temperature (e.g. about 250-350° F., preferably about 300°) clean condensate. Then the high temperature clean condensate is flashed in a plurality of flash stations to produce a heated vapor in a lower temperature clean condensate, and the heated vapor is used to heat the foul condensate in each of the direct contact heat exchangers. Typically the highest temperature is used to heat the highest temperature foul condensate, with progressively lower temperature vapors used to heat progressively lower temperature condensate stations. A vapor is produced during steam stripping, and using low pressure steam the vapor is reboiled to produce a discharge containing the majority of HAPs, and the HAPs in the discharge are destroyed in a conventional thermal destruct unit or in another conventional manner.
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