Patent Publication Number: US-2019186836-A1

Title: Conditioning apparatus and method for conditioning a gaseous medium, and installation and method for treating workpieces

Description:
The invention relates to a conditioning apparatus for conditioning a gaseous medium to yield a conditioned gaseous process medium, having
     a) an inlet connection unit and an outlet connection unit, between which is formed a flow path for gaseous medium having one or more conditioning stages, at least one of which comprises a heat exchanger;   b) the heat exchanger has a heat exchange chamber, in which a heat exchange element is accommodated at least in part and to which gaseous medium to be conditioned may be supplied, the heat exchanger comprising regions of sensitive material which may be damaged by the gaseous medium.   

     The invention further relates to a method for conditioning a gaseous medium and to an installation and a method for treating workpieces. 
     Conditioning apparatuses of the above-mentioned type are used for example in the automotive industry in installations for treating vehicle bodies and in this case in particular in treatment booths in which coated vehicle bodies are treated in the context of a painting process. These include in particular paint booths, and also for example evaporation booths, cooling booths and dryers, in each case having a treatment tunnel. 
     The tunnel air is circulated in such treatment booths and to this end is removed from the treatment tunnel as a gaseous medium to be conditioned and, after conditioning in a conditioning apparatus, resupplied to the treatment tunnel as conditioned process medium. However, the tunnel air contains aggressive constituents, which are released during treatment of the vehicle bodies. In a conditioning apparatus, the removed tunnel air passes through different conditioning stages, in which, among other things, aggressive constituents are removed and the humidity and temperature of the tunnel air are adjusted. The latter proceeds via heat exchangers. 
     However, heat exchangers have sensitive regions which may be damaged by the aggressive constituents of the tunnel air before they are removed from the tunnel air. Such sensitive regions are present in particular at heat exchanger tube connection points, which are generally soldered or brazed. 
     Components which are attacked by the aggressive constituents of the tunnel air therefore have frequently to be replaced after only a short service period, which drives up costs. 
     It is an object of the invention to provide a conditioning apparatus and a method for conditioning a gaseous medium and an installation and a method for treating workpieces which take account of these issues. 
     This object is achieved for a conditioning apparatus of the above-mentioned type in that
     c) a heat exchanger protection system is provided by means of which such sensitive regions of the heat exchanger may be exposed to a protective gas.   

     The invention is based on the recognition that effective protection of such sensitive regions of a heat exchanger may thereby be achieved. In principle, the protective gas may be any gas which is economically feasible and does not have any undesired properties. For example, compressed air from external sources, or indeed inert gases such as nitrogen or carbon dioxide may be used. Good use is made of the resources available if gas from the conditioning apparatus is used; this will be addressed in greater detail below. 
     In the simplest variant, the protective gas could be blown directly onto sensitive regions of the heat exchanger for example via one or more nozzles. It is however more effective for the heat exchanger protection system to comprise at least one protective housing, which surrounds one or more sensitive regions of the heat exchanger and to which protective gas may be supplied via a protective gas line. 
     It is particularly resource-efficient for the protective gas line to be connected to the flow path or downstream of the final conditioning stage in such a way that partly conditioned gas or process medium from the conditioning apparatus and serving as protective gas may be conveyed into the protective housing. 
     Advantageously, the protective housing comprises at least one protective gas outlet through which protective gas may flow, after flowing through the protective housing, into the heat exchange chamber. In this way, the protective gas is, as it were, circulated in the conditioning apparatus and may in this way once again contribute to the conditioned process medium. 
     In order to be able to adjust the volumetric flow rate of the protective gas, it is favorable for a protective gas blower and/or an adjusting valve to be arranged in the protective gas line. 
     Such a heat exchanger protection system may be used particularly effectively if sensitive regions of the heat exchanger are formed by tube connection points at which tubes or tube sections of the heat exchanger are joined fluid-tightly together. 
     The exposure to protective gas is particularly effective if tubes or tube sections of the heat exchanger are welded together or soldered or brazed together at tube connection points. Joining may also proceed by adhesive bonding or the like. Such connection points may be effectively protected. 
     If a plurality of conditioning stages are present which comprise a heat exchanger, it is favorable for these heat exchangers to be integrated into the heat exchanger protection system. 
     The above-stated object is achieved in a method for conditioning a gaseous medium in that a conditioning apparatus having some or all of the explained features is used. 
     In an installation for treating workpieces, the above-stated object is achieved in that it comprises a conditioning apparatus having some or all of the explained features. 
     In a method for treating workpieces, the above-stated object is achieved in that the workpieces are treated in an installation having some or all of the features explained above in relation to the installation. 
    
    
     
       Exemplary embodiments of the invention are explained in greater detail below with reference to the drawings, in which: 
         FIG. 1  shows a longitudinal section through a treatment means for treating vehicle bodies having a treatment tunnel, to which conditioned process air, which has been conditioned by means of a conditioning apparatus, is supplied by means of an air supply device, wherein the conditioning apparatus comprises at least one heat exchanger having a heat exchange coil; 
         FIG. 2  shows a longitudinal section through a modified conditioning apparatus; 
         FIG. 3  is a detail view of part of a heat exchanger protection system according to  FIGS. 8 to 11 , taking a heat exchanger as example, wherein a control device is additionally shown; 
         FIG. 4  shows the heat exchanger according to  FIG. 3  in plan view; 
         FIG. 5  is a perspective view of a modified heat exchanger; 
         FIG. 6  is a detail view of a portion of the heat exchanger of  FIG. 5 ; 
         FIG. 7  is a detail view of a plate heat exchanger with a heat exchanger protection system; 
         FIG. 8  shows a longitudinal section through the conditioning apparatus according to  FIG. 1  with a flow layout of the heat exchanger protection system according to a first exemplary embodiment; 
         FIG. 9  shows a longitudinal section through the conditioning apparatus according to  FIG. 1  with a flow layout of the heat exchanger protection system according to a second exemplary embodiment; 
         FIG. 10  shows a longitudinal section through the conditioning apparatus according to  FIG. 2  with a flow layout of the heat exchanger protection system according to a third exemplary embodiment; 
         FIG. 11  shows a longitudinal section through the conditioning apparatus according to  FIG. 2  with a flow layout of the heat exchanger protection system according to a fourth exemplary embodiment; 
         FIG. 12  shows a design of an installation for treating vehicle bodies which has two treatment tunnels arranged in parallel and each having a conditioning apparatus, these being connected together; 
         FIG. 13  shows a modified design of an installation for treating vehicle bodies which has two treatment tunnels arranged in parallel and each having a conditioning apparatus, these being connected together. 
     
    
    
     Reference will be made first of all to  FIGS. 1 and 2 , which show two different designs of conditioning apparatus  10 . 1  and  10 . 2  for conditioning a gaseous medium  12  to yield a conditioned gaseous process medium  14 . Hereinafter, general reference will be made to a conditioning apparatus  10 . 
     Such a gaseous medium  12  may for example contain an exhaust gas arising during a working process. In the exemplary embodiments described below, the gaseous medium  12  is by way of example at least in part exhaust air  16  which arises in a treatment means  18  with a treatment booth  20  of an installation, denoted overall  22 , for treating workpieces  24 . 
     Vehicle bodies are shown as examples of workpieces  24 . The workpieces  24  may however also be other workpieces and in particular add-on or mounting parts of vehicle bodies such as bumpers, side mirrors or the like. Smaller workpieces  24  may optionally be arranged on a workpiece holder, which is not in itself shown. 
     The treatment booth  20  of the treatment means  18  defines a workspace in the form of a treatment tunnel  26  having a tunnel entry  26   a  and a tunnel exit  26   b , through which the workpieces  24  to be treated are conveyed by means of a conveying system  28 , as known per se and which need not be addressed in any more detail. 
     The treatment tunnel  26  has an air outlet  30  and an air inlet  32 , between which the conditioning apparatus  10  is arranged, such that exhaust air  16  may be drawn out of the treatment tunnel  26 , passed through the conditioning apparatus  10  and, once conditioning is complete, recycled to the treatment tunnel  26  as process air  34 . The recycled process air  34  is guided to the workpieces  24  to be treated in a manner known per se via nozzles which are not in themselves illustrated. 
     This makes it possible to maintain the temperature and treatment conditions needed for effective treatment in the treatment tunnel  26 . In a modification which is not in itself shown, the treatment tunnel  26  may also be subdivided into a plurality of tunnel sections, which each have a separate air outlet and air inlet which are connected to the conditioning apparatus  10 . Optionally, each tunnel section present may also be associated with its own conditioning apparatus  10 , such that different temperatures and treatment conditions may be established in each tunnel section, as is in each case most favorable for the treatment procedure. 
     The conditioning apparatus  10  comprises an inlet connection unit  36  and an outlet connection unit  38 , between which a flow path is formed for gaseous medium  12  having a plurality of conditioning stages  40 , and multiple flow chambers  42  arranged between the conditioning stages  40 . In the exemplary embodiments according to  FIGS. 1 and 2 , six conditioning stages  40  are present, by way of example, which comprise a preheating device  40 . 1 , a first filter device  40 . 2 , a cooling device  40 . 3 , a reheating device  40 . 4 , a humidifier  40 . 5  and a second filter device  40 . 6 . 
     The conditioning apparatus  10  comprises a feed line  48  for gaseous medium  12  to be conditioned, which line leads into the inlet connection unit  36  and is connected on the inlet side with the air outlet  30  of the treatment means  18 . A valve  50  is arranged in the feed line  48 , such that the volumetric flow rate of the exhaust air  16  to the inlet connection unit  36  may be adjusted. 
     In the inlet connection unit  36 , the exhaust air  16  firstly flows into an inlet chamber  52 . The inlet connection unit  36  of the conditioning apparatus  10  is moreover connected with a fresh air line  54 , via which fresh air  56  may be guided from a fresh air source  58  into the inlet chamber  52 . A valve  56  is arranged in the fresh air line  54 , such that the volumetric flow rate of the fresh air  56  to the inlet connection unit  36  may also be adjusted. The conditioning procedure for the gaseous medium  12 , i.e. here the exhaust air  16  from the treatment tunnel  26 , consequently also includes admixing with the gaseous medium  12  a proportion of an admix gas, in the present case thus a proportion of fresh air  56 . As a consequence, a mixture of the gaseous medium  12  and fresh air  56  constantly flows through the conditioning apparatus  10 ; for the sake of simplicity, reference is made hereinafter however merely to the gaseous medium  12 . 
     From the outlet connection unit  38  of the conditioning apparatus  10 , a process medium line  62  with a valve  64  leads to the air inlet  32  of the treatment means  18 . Furthermore, a secondary process medium line  66  with a valve  68  leads away from the outlet connection unit  38 . 
     In the conditioning apparatus  10 . 1  shown in  FIG. 1 , the conditioning stages  40  downstream of the inlet chamber  52  are arranged in the following sequence in the direction of flow: preheating device  40 . 1 , first filter device  40 . 2 , cooling device  40 . 3 , reheating device  40 . 4 , humidifier  40 . 5  and second filter device  40 . 6 ; the blower  46  is located between the humidifier  40 . 5  and the second filter device  40 . 6 . In general terms, the blower  46  is here arranged on the outlet side of the conditioning apparatus  10 ; in a modification that is not in itself shown, it may also be arranged downstream of the last conditioning stage  40 , i.e. here downstream of the second filter device  40 . 6 . All the conditioning stages are here arranged in series, such that the entire gaseous medium  12  flows through them in succession. 
     In the conditioning apparatus  10 . 2  shown in  FIG. 2 , the blower  46  is arranged in the inlet chamber  52 . In general terms, the blower  46  is here arranged on the inlet side of the conditioning apparatus  10 ; in a modification not in itself shown it may also be arranged upstream of the inlet chamber  52 . Then, the preheating device  40 . 1 , the first filter device  40 . 2  and the reheating device  40 . 4  follow in series, such that the gaseous medium  12  flows as a whole through these conditioning stages  40 . The cooling device  40 . 3  and the humidifier  40 . 5  are arranged downstream of the reheating device in the direction of flow, but here in parallel, such that the stream of gaseous medium  12  is subdivided downstream of the reheating device  40 . 4  and one sub-stream  70 . 1  of the gaseous medium  12  flows through the cooling device  40 . 3  and one sub-stream  70 . 2  of the gaseous medium  12  flows through the humidifier  40 . 5 . Thereafter, the sub-streams  70 . 1 ,  70 . 2  are recombined in a mixing flow chamber  42   a  and the gaseous medium  12  flows through the second filter device  40 . 6  to the outlet connection unit  38  of the conditioning apparatus  10 . 2 . A flow chamber  42  is in each case provided up- and downstream of the reheating device  40 . 4  in the sub-stream  70 . 2 . 
     The preheating device  40 . 1 , the cooling device  40 . 3  and the reheating device  40 . 4  serve to adjust the temperature of the gaseous medium  12  and are designed as heat exchangers  72 , as illustrated by way of example in  FIGS. 3 and 4 . 
     The heat exchanger  72  comprises a heat exchange chamber  76  defined by a housing  74 , which chamber accommodates a heat exchange element in the form of a heat exchange coil denoted overall  78 . 
     The heat exchange coil  78  comprises an inflow tube  80  and an outflow tube  82 , apparent only in  FIG. 4 , for a heat exchange medium  84 , which may be gaseous or liquid. The inflow tube  80  and the outflow tube  82  are connected together by a plurality of heat exchanger tubes  86 , which are arranged spaced from one another. In general, a heat exchange element is a component of a heat exchanger through which heat exchange medium  84  may flow. 
     The heat exchanger tubes  86  take a serpentine course and to this end comprise tube sections  88  extending parallel to one another in a common plane, adjacent pairs of which are connected together in each case at alternate ends by a connecting tube in the form of a U-tube  90 . In the present exemplary embodiment, each heat exchanger tube  86  comprises four parallel tube sections  88  and three U-tubes  90 . The heat exchange medium  84  is supplied to the inflow tube  80  and flows from there through the heat exchanger tubes  86  into the outflow tube  82 , via which the heat exchange medium  84  is then carried away and subjected to its own conditioning procedure. 
     The inflow tube  80 , the outflow tube  82 , the tube sections  88  and the U-tubes  90  are generally made of copper and connected together in a fluid-tight manner in a manner known per se at the respective tube connection points, just a few of which are denoted  92 . The tubes may for example be soldered or brazed together, wherein solders or brazing metals known per se are accordingly likewise used. The tube connection points  92  may optionally also be formed by welding, for example if the tubes of the heat exchanger  72  are made from special steel. 
     The housing  74  has an inlet  94  and an outlet  96  for the gaseous medium  12 , which are only shown in  FIG. 4 , such that the gaseous medium  12  requiring temperature adjustment may flow through the heat exchange chamber  76  and in the process over the heat exchanger tubes  86 , such that the desired heat exchange with the gaseous medium  12  may proceed in conventional manner. 
       FIG. 5  shows a modified heat exchanger  72  in which the inflow tube  80  and the outflow tube  82  are connected together not via multiple, but rather in each case via one connecting tube in the form of a 90° elbow  98  at tube connection points  92  via a single heat exchanger tube  86 , which forms a relatively large number of parallel tube sections  88  defined as the heat exchanger tubes  86  of the heat exchanger  72  according to  FIGS. 3 and 4 . The direction of flow of the gaseous medium  12  perpendicular to the plane defined by the tube sections  88  is shown in  FIG. 5  by a plurality of arrows. 
     As explained above, the tube connection points  92  in particular define regions of material in heat exchange coils  78  which are sensitive and may be damaged by the gaseous medium  12 . The exhaust air  16  from the treatment tunnel  26 , which flows through the conditioning apparatus  10 , entrains aggressive constituents which attack the tube connection points  92  of the heat exchange coil  78  and endanger the tightness of the system. 
     To reduce and ideally to eliminate this harmful effect, a heat exchanger protection system  100  is provided. This comprises one or more protective housings  102 , which each define a protective chamber  104  and which surround one or more such sensitive regions, i.e. in the present exemplary embodiment one or more of the tube connection points  92 . Each protective housing  102  has a protective gas inlet  106 . The protective gas inlet  106  is connected with an outlet connection  108   a  of a protective gas line  108 , which is not shown in all the figures and via which a protective gas  110  may be supplied to the protective chamber  104 . At the end thereof remote from the protective gas inlet  106 , the protective gas line  108  has an inlet connection  108   b . If multiple protective housings  102  are present, as is the case in  FIG. 3 , each protective housing  102  may be connected with a separate protective gas line  108  or the protective gas line  108  may be branched into a number of distribution arms  108   c , each of which leads to a protective housing  102 ; the latter is shown in  FIG. 3  through the example of two protective housings  102  and two distribution arms  108   c  of the protective gas line  108 . 
     As an overarching concept, sensitive regions of the heat exchanger  72  may be exposed to the protective gas  110  by means of the heat exchanger protection system  100 . 
     As a result of this measure, it is possible to prevent the sensitive regions from coming into contact with other media. 
     The protective housing  102  comprises a plurality of passage openings  112 , through which the tube sections  88  of the heat exchange coil  78  extend, such that the connecting tubes thereof, i.e. in this case the U-tubes  90  and/or the 90° elbow  98  and above all the tube connection points  92 , are arranged inside the protective housing.  FIG. 6  illustrates this concept through the example of the heat exchanger  72  according to  FIG. 5 . 
     These passage openings  112  are not sealed relative to the tube sections  88  or connected rigidly therewith, so making allowances for thermal expansion of the components, which might otherwise lead to material stresses. Instead, an annular gap  114  remains between the passage openings  112  and the tube sections  88 , through which gap, after flowing through the protective housing  102 , the protective gas  110  may flow into the heat exchange chamber  76  of the heat exchanger  72 , where it mixes with the gaseous medium  12  flowing therein. The passage openings  112  of the protective housing  102  or the annular gap  114  in this way form protective gas outlets for the protective housing  102 . If a sealed joint or at least largely sealed joint is possible between the protective housing  102  and the tube sections  88 , the protective housing  102  has one or more separate protective gas outlets. Alternatively, a static pressure may be maintained in the protective housing  102  even without further outlets. 
       FIG. 7  again shows a modified heat exchanger  72 , which is designed as a plate heat exchanger  116  and comprises as heat exchange elements a plurality of heat exchanger plates  118  through which heat exchange medium  84  may flow and which are connected fluidically together via connecting tubes  120  and on the inlet side with the inflow tube  80  and on the outlet side with the outflow tube  82 . Each connecting tube  120  has a connection point  92  at each end. In this case a protective housing  102  with a protective gas inlet  106  is present for each connecting tube  120 , wherein in addition to each connecting point  92  a passage opening  112  of the protective housing  102  is present through which a respective connecting tube  120  exits from the associated protective housing  102  at both ends of the protective housing  102 . In this embodiment, an annular gap  122  remains between a heat exchanger plate  118 , the connecting tube  120  joined thereto and the protective housing  102 , through which gap protective gas  110  may flow out of the protective housing  102  and into the heat exchange chamber  76 . 
     Overall, the protective gas  110  acts as a barrier gas, in the case of air therefore as barrier air, relative to the gaseous medium  12  in the heat exchange chamber  76 . Conditioned process medium  14  or partly conditioned gas from the conditioning apparatus  10  serves as the protective gas  110  for the heat exchanger protection system  100 . Partly conditioned gas is gas which is removed from the conditioning apparatus  10  before it flows into the process medium line  62 , wherein this gas is conditioned such that it can no longer damage sensitive regions of the heat exchanger  72  or at least to a lesser degree than the gaseous medium  12 . 
       FIGS. 8 to 10  show various exemplary embodiments of a flow layout of the heat exchanger protection system  100 , wherein in  FIGS. 8 to 10  only the basic components and parts have reference signs. 
     In the exemplary embodiment according to  FIG. 8  with the conditioning apparatus  10 . 1 , the inlet connection  108   b  of the protective gas line  108  is connected downstream of the blower  46  with the conditioning apparatus  10 . 1 , such that protective gas  110  is conveyed into the protective gas line  108  by means of the blower  46 . Specifically, the protective gas line  108  is connected to the flow chamber  42  between the blower  46  and the second filter device  40 . 6 . 
     In a modification not in itself shown, the protective gas line  108  may also be connected downstream of the final conditioning stage  40 , for example to the outlet connection unit  38  or to the process medium line  62 . In this case, conditioned gas, i.e. here the conditioned, gaseous process medium  14 , serves as protective gas  110 . 
     As illustrated in  FIG. 3 , an adjusting valve  124  may be arranged in the protective gas line  108 , such that the proportion of the gas flowing through the conditioning apparatus  10 . 1  which is removed as protective gas  110  may be adjusted. 
     The protective gas line  110  leads to the preheating device  40 . 1 , where it is connected with the protective housings  102  provided therein of the heat exchanger protection system  100 ; this is not visible in  FIG. 8 . In general terms, the protective gas line  108  is connected with the heat exchanger  72  of the inlet-side conditioning stage  40 , irrespective of whether cooling or heating is taking place at that point. The gaseous medium  12  to be conditioned has its most highly aggressive and corrosive action at the inlet of the conditioning apparatus  10 , since at that point the gaseous medium  12  has not undergone any treatment of any sort, apart from any addition of fresh gas. If the aggressive and corrosive action of the gaseous medium  12  has accordingly been eliminated once it has flowed through the first filter device  40 . 2 , in subsequent conditioning stages  40  the heat exchangers  72  do not have to be integrated into the heat exchanger protection system  100 ; protective housings  102  are then accordingly not provided there. 
     However, one or more further conditioning stages  40 , in which a heat exchanger  72  is present, may also be integrated into the heat exchanger protection system  100 , and the protective housings  102  may in this case be connected with the protective gas line  108 , to which end these are then branched into a corresponding number of side arms which then in turn optionally fork again as required into distribution arms  108   c . In a modification, a separate protective gas line  108  may also lead to each conditioning stage  40  in question. 
     To clarify this, in the exemplary embodiment according to figure all the conditioning stages  40  present in the conditioning apparatus  10 . 1  which have heat exchangers  72  are integrated into the heat exchanger protection system  100 . In this case, these are therefore the preheating device  40 . 1 , the cooling device  40 . 3  and the reheating device  40 . 4 . The side arms just discussed above of the protective gas line  108  are denoted  108   d.    
     Unlike in the exemplary embodiment according to  FIG. 8 , the inlet connection  108   b  of the protective gas line  108  is connected with the conditioning apparatus  10  upstream of the blower  46 . Specifically, the protective gas line  108  is there connected with the flow chamber  42  between the reheating device  40 . 4  and the humidifier  40 . 5 . In addition, a separate protective gas blower  126  is also arranged in the protective line  108 , so that protective gas  110  may be drawn off from the conditioning apparatus  10 . 2  and conveyed to the connected conditioning stages  40 . The protective gas blower  126  is also shown in  FIG. 3 . 
     In the exemplary embodiment according to  FIG. 10  with the conditioning apparatus  10 . 2 , the protective gas line  108  extends between the flow chamber  42 , which is arranged upstream adjacent the reheating device  40 . 4  and humidifier  40 . 5 , and the first conditioning stage  40  in the direction of flow, in this case the preheating device  40 . 1 . 
     The exemplary embodiment according to  FIG. 11  shows a variant of the conditioning apparatus  10 . 2  in which the inlet connection  108   b  of the protective gas line  108  is connected with the flow chamber  42 , which is placed in this case between the reheating device  40 . 4  and the mixing flow chamber  42   a . The protective gas line  108  leads from there via side arms  108   d  to the first two conditioning stages  40 , which comprise a heat exchanger  72 ; these are in this case the preheating device  40 . 1  and the cooling device  40 . 3 . 
     The statements made above in relation to the conditioning apparatus  10 . 1  apply mutatis mutandis to possible modifications. 
       FIG. 3  additionally depicts a control device  128  of the heat exchanger protection system  100 . This comprises a control unit  130 , by which the adjusting valve  124  and/or the protective gas blower  126  may be controlled, if these are present. Furthermore, the control device  128  comprises sensors  132 , with which predetermined properties of the protective gas  110  may be detected. In practice, these are humidity sensors.  FIG. 3  shows data and control lines dash-dotted and without their own reference signs. 
       FIGS. 12 and 13  show a modified installation  22 , which comprise two treatment means  18 . 1  and  18 . 2  which may be operated in parallel. Each treatment means  18 . 1 ,  18 . 2  comprises its own conditioning apparatus  10 . 
     In the exemplary embodiment according to  FIG. 12 , a secondary line  136  branches off from the protective gas line  108  of the conditioning apparatus  10  of the treatment means  18 . 1  downstream of the protective gas blower  126 , which secondary line leads to the conditioning apparatus  10  of the treatment means  18 . 2  and is there connected to the protective housing  102  for one of the heat exchangers  72  of one of the conditioning stages  40  present. In the protective line  108 , a further adjusting valve  138  may be provided upstream of the branch point, likewise in the secondary line  136 . 
     In a modification, the protective gas line  108  of the conditioning apparatus  10  of the treatment means  18 . 1  may also branch into a plurality of such secondary lines  136 , to which the conditioning apparatus  10  of the treatment means  18 . 2  is connected. 
     In the exemplary embodiment according to  FIG. 13 , the protective gas lines  108  of the two conditioning apparatuses  10  of the treatment means  18 . 1  and  18 . 2  have a common line portion  140 , so establishing a type of crossover arrangement of protective gas lines  108 . The protective gas blower  126  is arranged in this common line portion  140 . In this way, the protective gas  110  from the two conditioning apparatuses  10  may be distributed to the respective heat exchangers  72  or the protective housings  102  present there. 
     Otherwise, the statements made in relation to the other exemplary embodiments with regard to possible modifications of the line arrangements accordingly also apply mutatis mutandis to the variants according to  FIGS. 12 and 13 . 
     As is apparent from  FIGS. 12 and 13 , a protective gas conditioning unit  142  may moreover also be provided in the protective gas line  108 , with which protective gas conditioning unit the protective gas  110  may optionally be additionally conditioned for its intended purpose. This also applies to all the other exemplary embodiments. 
     For example, the protective gas conditioning unit  142  may be designed as a dehumidifier, if the protective gas  110  of the conditioning apparatus  10  is only removed downstream of the humidifier  40 . 5 . An excessively humid protective gas  110  could put unnecessary strain on the tube connection points  92 . However, heating or cooling units or indeed combinations with differently acting units may also be provided.