Abstract:
A method for determining fractions of coolants emitted into the atmosphere in processes using coolants, in particular in the metal processing industry. Here, samples of the atmosphere polluted with fractions of coolants in droplet and vapor form are fed to an evaporator. In the evaporator, the fractions of coolants in droplet form contained in the samples are evaporated and subsequently the vapor resulting from the fractions of coolants in droplet form is fed to an analysis unit, in particular a flame ionization detector, together with the fractions of coolants in vapor form contained in the samples. In the analysis unit the concentrations of the coolants contained in the samples are ascertained.

Description:
BACKGROUND OF THE INVENTION  
     FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method for determining the fractions of coolants emitted into the atmosphere in processes using coolants, in particular in the metal processing industry, and to a device for carrying out the method.  
         [0002]     Metal processing requires the use of coolants which lubricate the contact surfaces in order to reduce friction, to dissipate the heat occurring in the processing, and also to convey away chips and the like. Mineral oils, natural oils or synthetic oils or water/oil emulsions containing from 2% to 10% of oil are used as coolants. Coolant emulsions are particularly advantageous on account of their high cooling capacity and the fact that they do not cause risk of fire or explosions.  
         [0003]     With the use of coolants in metal processing the atmosphere is, however, polluted with fractions of coolants in droplet and vapor form emitted into the atmosphere. With respect to this pollution, standardized values for the exposure limits at the workplace apply to the concentration of fractions of coolants in droplet and vapor form, which values relate to the oil fractions and must not be exceeded. This is why the concentrations of emissions polluting the atmosphere need to be determined for different types and compositions of coolants, in different processes, under different conditions and the like, first in order to ensure that existing standards are complied with, and second in order to achieve optimizations with regard to minimizing pollution of the atmosphere when coolants are used.  
         [0004]     It is known to determine emissions from coolants by filtering off the fractions in droplet form from samples of the atmosphere polluted by coolants via filters and by binding the fractions in vapor form by use of adsorber resins, the fractions of coolants contained in the waste air being ascertained by weighing the filters and eluting the adsorber resins and analyzing the eluate. It is, however, not possible to determine the sizes of the fractions in droplet form by these methods, notwithstanding the fact that these are complicated and time-consuming methods.  
         [0005]     It is furthermore known to determine the number and sizes of the fractions of coolants in droplet form contained in the atmosphere using a light scattering particle counter. This method is advantageous when compared to filtration as quick results are possible. However, this method fails to meet requirements as in many respects it yields incorrect results. This is because, if the emissions of coolants which are not emulsified in water are determined, the measurement results for the fractions in droplet form emitted into the atmosphere are correct. However, only the fractions in droplet form, and not the fractions in vapor form are measured using a light scattering particle counter.  
         [0006]     If, on the other hand, the emissions of coolants emulsified in water are to be determined, which is usually the case in view of the special advantages of coolant emulsions, this method not only has the disadvantage that the fractions in vapor form are not detected, but this method has the further disadvantage that only the number and sizes of the fractions in droplet form are detected. But no statements can be made with regard to the amounts of coolants in volume units, since the fractions in droplet form contain different contents of coolants.  
       SUMMARY OF THE INVENTION  
       [0007]     It is accordingly an object of the invention to provide a method and a device for determining the fractions of lubricants emitted into the atmosphere in coolant processes that overcome the above-mentioned disadvantages of the prior art methods and devices of this general type, by which a total content of coolants contained in one volume unit in the samples as fractions in droplet and vapor form can be measured, and in which the measurement result is available quickly.  
         [0008]     According to the invention, the objects are achieved in that the samples of the atmosphere polluted with fractions of coolants in droplet and vapor form are fed to an evaporator. In the evaporator, fractions of coolants in droplet form contained in the samples are evaporated and in that subsequently the vapor resulting from the fractions of coolants in droplet form is fed to an analysis unit, in particular a flame ionization detector, together with the fractions of coolants in vapor form contained in the samples. The analysis unit then determines the concentrations of the coolants contained in the samples.  
         [0009]     Preferably the number of hydrocarbon atoms contained in volume units of the samples is determined in the analysis unit. Furthermore it is preferred to heat the samples in the evaporator to 300° C. to 400° C., as a result of which the fractions of coolants in droplet form contained therein are evaporated, whereupon the samples are fed to the analysis unit, in particular the flame ionization detector, at a temperature of approximately 300° C.  
         [0010]     The method makes it possible to quickly check samples of atmosphere loaded with coolants for the amounts of the fractions of coolants contained therein. The measurement results being independent of whether the fractions are fractions of coolants in droplet or vapor form, and it furthermore being irrelevant whether the samples involved are pure coolants (not mixed with water) or coolant emulsions.  
         [0011]     It is not possible, however, to use the method to determine the sizes of the fractions of coolants in droplet form contained in the polluted atmosphere. If the fractions in droplet form need to be determined according to their size as well, the fractions of coolants in droplet form contained in the samples are furthermore fractionated according to their sizes and the fractions of the samples, which fractions are fractionated according to their sizes, are fed to the evaporator. In this case, fractionation of the fractions according to size can take place using so-called impactors.  
         [0012]     According to the method, in each case those fractions in droplet form which exceed a respectively prespecified size can be separated out in successive steps from the samples of the atmosphere polluted with coolants, whereby in a first step only those fractions in droplet form which do not exceed a certain size and the fractions of coolants in vapor form contained in the relevant sample are detected. In further steps, in each case the fractions in droplet form up to the respective maximum size and the fractions in vapor form are detected. The contents of fractions of coolants in droplet form in the relevant sample in certain size ranges can be detected by subtracting the measurement values obtained in the respectively preceding steps.  
         [0013]     In a final step, a sample which contains all fractions of coolants in droplet and vapor form contained in the sample is fed to the evaporator and the analysis unit. The amounts of the fractions in droplet form in the relevant size ranges can be ascertained by subtracting the measurement values ascertained in the respectively preceding steps. In order to detect the fractions of coolants in vapor form in the samples in the best possible manner, the lowermost size of the fractions in droplet form is selected to be as small as possible.  
         [0014]     Preferably the samples are fed to the evaporator on the one hand, and the light scattering particle counter on the other hand, as a result of which it is also possible to ascertain the size distribution of the fractions in droplet form.  
         [0015]     A device according to the invention for carrying out the process has an evaporator and an analysis unit, in particular a flame ionization detector, to which samples of the atmosphere polluted with coolants can be fed. Preferably a blower for conveying the samples is provided. According to a further preferred embodiment, a plurality of apparatuses for fractionating the samples according to prespecified sizes of the fractions of coolants in droplet form are located upstream of the evaporator, it being possible for only one specific sample to be fed to the evaporator by a control device. Preferably, a light scattering particle counter is additionally provided. Preferably the evaporator is furthermore connected to the analysis unit, in particular the flame ionization detector, via a heated line.  
         [0016]     Other features which are considered as characteristic for the invention are set forth in the appended claims.  
         [0017]     Although the invention is illustrated and described herein as embodied in a method and a device for determining the fractions of lubricants emitted into the atmosphere in coolant processes, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
         [0018]     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is a diagrammatic illustration of a first embodiment of a device for determining fractions of lubricants emitted into the atmosphere in coolant processes according the invention; and  
         [0020]      FIG. 2  is a diagrammatic illustration of a second embodiment of the device for determining fractions of lubricants emitted into the atmosphere in coolant processes according the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown a line  21  leading to an apparatus  2  for fractionating fractions of coolants in droplet form according to their sizes. The line  21  projects into an interior  10  of a channel  1 , in which waste air polluted with fractions of coolants in droplet and vapor form flows. The apparatus  2  has a plurality of parallel channels  23 ,  24 ,  25  and  26  through which samples of the waste air polluted with fractions of coolants in droplet and vapor form are introduced, as desired, via the line  21  by a control device  22  located upstream of the apparatus  2 . In the channels  23 ,  24  and  25  there are apparatuses  23   a ,  24   a  and  25   a , by which the fractions of coolants in droplet form contained in the samples are fractionated based on their sizes. By way of example, all fractions in droplet form whose diameter exceeds the value of 0.3 μm are removed via apparatus  23   a , all fractions in droplet form whose diameter exceeds the value of 1 μm are removed via apparatus  24   a , and all fractions in droplet form whose diameter exceeds the value of 2 μm are removed via apparatus  25   a . These apparatuses contain, for example, so-called impactors.  
         [0022]     By contrast, all fractions of coolants in droplet and vapor form contained in the relevant sample pass through channel  26 . Channels  23 ,  24 ,  25  and  26  issue in line  27  where the waste air polluted with fractions of coolants in droplet and vapor form is discharged by a blower  28 .  
         [0023]     A line  31  projects into an interior of line  27 , which line  31  leads to an evaporator  3 . A heated line  41  leads from the evaporator  3  to an analysis unit  4  which contains, for example, a flame ionization detector. A line  42  in which a blower  43  is situated follows the analysis unit  4 . A line  51  leading to a light scattering particle counter  5  projects into the channel  1 . A line  52  in which another blower  53  is situated branches off from the light scattering particle counter  5 .  
         [0024]     The method of operation of the device is now described. Samples of the waste air polluted with fractions of coolants in droplet and vapor form are taken, via line  21 , by use of the blower  28  from channel  1  in which the waste air flows. The samples are guided through one of the channels  23 ,  24 ,  25  and  26  of apparatus  2  by the control device  22 . The apparatuses  23   a ,  24   a  and  25   a  for fractionating the fractions of coolants in droplet form contained in the samples are situated within the channels  23 ,  24  and  25 .  
         [0025]     All fractions of coolants in droplet form whose diameter is larger than 0.3 μm are removed via apparatus  23   a , by way of example.  
         [0026]     All fractions in droplet form whose diameter is larger than 1 μm are removed via apparatus  24   a , by way of example.  
         [0027]     All fractions in droplet form whose diameter is larger than 2 μm are removed via apparatus  25   a , by way of example.  
         [0028]     By contrast, all fractions of coolants in droplet and vapor form contained in the samples pass through channel  26 .  
         [0029]     Furthermore, fractions of the samples are fed to the evaporator  3  via line  31  by the blower  43 , in which evaporator the fractions of coolants in droplet form contained in these samples are evaporated at a temperature of approximately 300° C. to 400° C. The outlet of the evaporator  3  is guided via the line  41 , which is preferably heated, to the analysis unit  4  for determining the amounts of hydrocarbon contained in the samples.  
         [0030]     If a sample contained in the waste air is guided through channel  26  in apparatus  2 , it contains both the fractions of coolants in droplet form and the fractions in vapor form. The analysis unit  4  detects all hydrocarbon atoms, irrespective of whether they were contained in the sample in the liquid or the gaseous phase. Thus the loading of the atmosphere with the fractions of coolants finding their way into the atmosphere on account of coolant processes is determined this way.  
         [0031]     If it is also to be determined what size distribution the fractions in droplet form have and to what extent the fractions in droplet form, on the one hand, and the fractions in vapor form, on the other hand, of the coolants are contained in the samples, samples taken from the waste air are successively passed through the channels  23 ,  24  and  25 , the fractions in droplet form contained in the samples being fractionated according to their sizes.  
         [0032]     Since only those fractions of coolants in droplet form whose diameter is less than 0.3 μm pass through the channel  23  into the evaporator  3 , the content of coolants contained in those fractions in droplet form whose diameter is less than 0.3 μm and in the fractions in vapor form in the relevant sample can be determined in this way.  
         [0033]     Since only those fractions of coolants in droplet form whose diameter is less than 1 μm and the respective fractions in vapor form pass through the channel  24  into the evaporator  3 , and only those fractions of coolants in droplet form whose diameter is less than 2 μm and the respective fractions in vapour form pass through the channel  25  into the evaporator  3 , it is possible to carry out a corresponding analysis in this way.  
         [0034]     All fractions of coolants in droplet and vapor form pass through channel  26 .  
         [0035]     Thus the fractions of coolants in vapor form in the samples, on the one hand, and the contents of the fractions of coolants in droplet form with diameters of less than 0.3 μm, from 0.3 μm to 1 μm, from 1 μm to 2 μm and of more than 2 μm can be ascertained by subtracting the measurement results of the respectively preceding samples. This way it is furthermore possible to ascertain, on the one hand, the fractions of coolants in vapor form on their own, and, on the other hand, all the the fractions of coolants in droplet form on their own.  
         [0036]     In order to detect the fractions of coolants in vapor form, the lowermost threshold value is selected to be as small as possible. By way of example, the lowermost threshold value can lie in the range from 0.1 μm to 0.5 μm.  
         [0037]     If the size distributions of the fractions of coolants in droplet form in the samples are also to be ascertained, fractions of the samples are fed, via line  51 , by a fan  53  to a light scattering particle counter  5 . This makes it possible for the size distributions of the fractions of coolants in droplet form in the individual samples to be ascertained and for them to be related to the measurement results obtained by the analysis unit  4 .  
         [0038]      FIG. 2  illustrates a second embodiment variant of the device according to the invention. Here, the impactor  25   a , via which those fractions in droplet form whose diameters are larger than 2 μm are removed, also the impactor  24   a , via which those fractions in droplet form whose diameters are larger than 1 μm are removed, and the impactor  23   a , via which those fractions in droplet form whose diameters are larger than 0.3 μm are removed, are disposed successively in line  21 .  
         [0039]     Lines  61 ,  62 ,  63  and  64  leading to a control device  60  branch off of line  21 , by which the samples passing through lines  61  to  64  are fed to the evaporator  3  and the analysis unit  4 , which results in the evaluations.  
         [0040]     The method of operation here is as described with reference to  FIG. 1 .  
         [0041]     This application claims the priority, under 35 U.S.C. §119, of Austrian application A 1390/2005, filed Aug. 22, 2005; the prior application is herewith incorporated by reference in its entirety.