Method and device for treating process air
The invention relates to a method for treating process air from an industrial process involving a main flow, wherein at least a proportion of the process air is treated using the following method steps: a first condensation step, in which a first condensate is separated out of the process air and is fed to a first recovery process; and a second condensation step, which takes place after the first condensation step and in which a second condensate is separated out of the process air and is fed to a second recovery process, wherein the lowest process air temperature that is reached in the second condensation step is lower than the lowest process air temperature that is reached in the first condensation step.
1 . A method of treatment of process air from an industrial process having a main stream and a secondary stream, with a respective volume flow in the main stream and in the secondary stream, wherein at least a portion of the process air is treated by the following method steps:
a first condensation step in which a first condensate is separated out of the process air and fed to a first recovery process,
a second condensation step that takes place after the first condensation step, in which a second condensate is separated out of the process air and fed to a second recovery process,
wherein the lowest process air temperature attained in the second condensation step is lower than the lowest process air temperature attained in the first condensation step
wherein a portion of the process air is branched off after the first condensation step from the main stream in a branch into the secondary stream for treatment by the second condensation step; and
wherein the volume flow branched off into the secondary stream is smaller than the volume flow present in the main stream downstream of the branch.
2 . The method as claimed in claim 1 for recovery of at least one solvent, wherein the first condensate includes a first solvent and the second condensate includes a second solvent, wherein first and/or second solvent comprise a hydrocarbon compound.
3 . The method as claimed in claim 1 , in which at least a portion of the process air is subjected to further treatment after the first condensation step in a first further treatment step,
wherein the first further treatment step comprises at least one selected from the group consisting of: a supply of heat, a lowering of pressure, and a second feed of air outside the main stream,
wherein at least a portion of the process air, after the first further treatment step, is returned to an industrial process.
4 . The method as claimed in claim 3 , in which the first further treatment step takes place downstream of the branch.
5 . The method of claim 4 , in which the first further treatment step takes place downstream of the branch with supply of heat in the first further treatment step.
6 . The method as claimed in claim 1 , in which at least a portion of the process air is subjected to further treatment in a second further treatment step downstream of the second condensation step,
which second further treatment step comprises at least one selected from the group consisting of: a supply of heat, a lowering of pressure, a filtering operation, a third condensation step, and an adsorbing operation.
7 . The method as claimed in claim 6 , in which at least a portion of the process air downstream of the second further treatment step is fed to an environment.
8 . The method as claimed in claim 6 , in which at least a portion of the process air downstream of the second further treatment step is returned to an industrial process.
9 . The method as claimed in claim 1 , in which at least a portion of the process air from the industrial process is guided into the main stream and at the same time filtered.
10 . The method as claimed in claim 1 , in which the industrial process comprises a drying process.
11 . The method as claimed in claim 1 , wherein the method comprises collecting the first condensate in the first recovery process and/or collecting the second condensate in the second recovery process for recycling into an industrial process.
12 . The method as claimed in claim 1 , wherein the method comprises recovery of heat in the first and/or second and/or third condensation step.
13 . The method as claimed in claim 1 , in which a deicing step takes place in the second condensation step, wherein the deicing step comprises at least one selected from the group consisting of:
intermittently interrupting the feed of at least a portion of the process air to the second condensation step, bypassing at least a portion of the process air from the second condensation step, and dividing the feed of the process air to the second condensation step into a plurality of substreams, wherein the deicing takes place in one of the plurality of substreams.
14 . An apparatus for treatment of process air from an industrial process, with
a main stream,
a first condenser comprising a first cooling element, a first heating element, and a first separator, wherein the process air is guided in the main stream to the first condenser, cooled by the first cooling element within the first condenser, and then passed through the first separator, wherein a first condensate is separated out of the process air and fed to a first recovery process,
a second condenser, connected downstream of the first condenser, comprising a second cooling element and a second separator,
wherein the process air is cooled by the second cooling element within the second condenser and then passed through the second separator,
wherein a second condensate is separated out of the process air and fed to a second recovery process
a branch from the first separator, wherein a portion of the process air, upstream of the first heating element, is branched off from the main stream in the branch into a secondary stream to the second condenser.
15 . The apparatus as claimed in claim 14 , having a diversion apparatus, wherein at least a portion of the process air is branched off into a secondary stream downstream of the first separator in a branch, wherein the diversion apparatus comprises at least one selected from the group consisting of: a first valve and a fan for guiding at least a portion of the process air.
16 . The apparatus as claimed in claim 14 , wherein the first cooling element comprises a first heat exchanger for recovery of heat in the first condenser, wherein at least a portion of the process air is subjected to further treatment in the first condenser after the first condensation step,
wherein a first air heater is disposed downstream of the first condenser.
17 . The apparatus as claimed in claim 14 , wherein the second cooling element comprises a second heat exchanger for recovery of heat in the second condensation step, wherein at least a portion of the process air is subjected to further treatment in the second condenser after the second condensation step,
wherein the second condenser comprises a second heating element for heating of the process air.
18 . The apparatus as claimed in claim 14 , wherein a second further treatment apparatus is disposed downstream of the second condenser, wherein the process air is subjected to further treatment by the second further treatment apparatus, wherein second further treatment apparatus comprises at least one selected from the group consisting of:
a filter,
a third condenser, and
a concentrator.
19 . The apparatus as claimed in claim 14 , having
a first condensate collector,
wherein the first condensate is collected in the first recovery process for recycling into the industrial process,
a second condensate collector,
wherein the second condensate is collected in the second recovery process for recycling into the industrial process.
20 . The apparatus as claimed in claim 14 , wherein the second condenser has a deicing apparatus.
21 . The apparatus as claimed in claim 14 , wherein the industrial process comprises the coating of a conductive carrier material, with a solvent-containing substance mixture as coating and drying after application of the coating on the carrier material, forming solvent-containing process air which is fed to the apparatus.