Clay processing Plants and gear Lubrication

Clays are the basis for a number of products, but the equipment necessary for processing the clay is much the same in each instance; consequently, lubrication problems have much in common. Clay based industries include brick manufacture, ceramics and tile. The earth may either be prepared at the point of consumption or crushed and ground at the mine for shipment. Normally, clay come from the mines or quarries as hard lumps which may be fed to a jaw or single roll crusher. The nature of the clay determines the method of crushing or grinding. Soft, friable earths require only crushing; while others have the particles partially cemented together and must be ground. Most of the drives for either purpose are by motors and reduction gears. These gears may be enclosed or open. The enclosed gears throughout the plants may be lubricated with oil 300 to 500 SUS at 100 degree F. This can be either a straight mineral oil or one containing a mild EP additive. Dust is almost certain to work into gear cases and, therefore, with large installations, circulating oil which can be filtered is desirable. Where this is not practical, the gear boxes should be drained every two to six months, flushed out and refilled. Open gears may be lubricated with a residuum of about 2000 viscosity SUS at 210 degree F which can be warmed for application. Frequent use will help flush off dust which becomes mixed with the lubricant. Following crushing or grinding, the clay is screened and the entire process may be repeated to obtain the desired fineness. Most clay is next mixed with water in pug mills and then are extruded or formed into desired articles. From such operations most clay based products are handled on conveyors unless placed on carts or cars for drying and burning or vitrifying. Even then, if the kilns are of the tunnel variety, further conveyor chains may move the carts through the kiln. Much of this equipment is driven by reduction gears, often enclosed. Therefore the same type and grade of lubricants as were mentioned earlier can be used throughout the plant. Gears should not be present in kilns and, therefore, are not subjected to any great heat. Other types of equipment, if present, can receive similar lubrication. These might include drives for elevators, augers, cutting machines and fans.     

Continuous Automatic Bending

Continuous  automatic blending of  gear  oils  is  accomplished  by  synchronizing  a  series  of pumps  and  meters  so that  desired  proportions  of  ingredients are  fed  to a  blender  or  homogenizer  where  the  mixing  is  completed. Such  a  blender  is of  rather  small   cubical  capacity, perhaps  holding  a  barrel  of  fluid; therefore , the  entire  system  contains  a minimum of  fluid at any one time. For this reason changes from one grade to another necessitates very little rejection of oil. Several  equipment  manufacturers  offer  systems  to  accomplish  the above  purpose  and most  compounders  rely  on  such  firms  rather  than  design their  own  blending  equipment. Details of such systems, which include “Bowser Blending Systems”, “Cornell Proportioning Units” or    “Proportioneers Oils Bending Unit”, can be obtained from the distributers.

                                                                                        

One such unit which is used for blending gear oils is shown. In this  instance  the  supply  of oil  comes  from storage tanks  outside  the  building, and  the  pumps at the tanks  are remotely  controlled at the  blending  unit. The oil passes through air eliminators, pressure controlled, and automatic temperature compensating proportioning meters. From  the  three  meters  the  fluid  goes  into  a common  header, through  a  master    meter, and  then  into the  blender from which  it can  go to  storage  or   through a small  surge  tank  to  package. This  unit is installed      over  a  great  which  allows  any  spillage  to  drain to a waste  tank  in the  basement of the  building. With  such  systems  two  to  six  or  eight  different  components can be  blended. While  there  are  variations  in the  different  systems, a typical  one  uses  a series  of  positive  displacement  piston   type  meters in which  a  selector  at the  top  of the  meter  sets a train  of  gears  to  determine   the  delivery. The flow rates of a ¾ in. meter can be varied   from 0.4   to 15 gpm and of a 3 in. size from 10 to 250 gpm. 

Where  a  single  additive is    to be  introduced  into    an oil  and  no further  blending  is  desired, a  continuous  system of injection   mixing  can be used. One  of the  most  positive  means for  injection  mixing  is to  use  an  injection   pump  driven  by  a motor  which  is controlled  by  an  interlocking  switch  connected  to that  of the oil  line  pump  motor. The  injection  pumps  are  generally  adjustable  over  a 10  to  1  capacity range and have capacities  varying from 5 cc/min to 40 gpm. No pump is required if the additive is introduced by the pressure of a closed tank. In  this case  a flow  indicator, such  as a “Rotometer ,”  can  be  included in the  additive  line  and  a  calibration point arrived  at  by  checking  the  consumption  of  the  additive  over  a given  period  with  the  gallonage  of oil  pumped.

In  these   automatic  blending  units  provision  is made  to  either  stop  the  flow  or  continuously  recycle  the  mixture  without  delivery  if  the  flow  of  one  or  more  of the  ingredients cease. Also, when  changing  blends  the  mixer  can  be  either  sucked  or blown  dry to  prevent  contamination. Since  continuous  automatic  blending  of gear  oils  decreases  the  labor  and  supervision  of such  operations  and   also  affords  considerable  saving  in space  requirements, such  methods  should  have  consideration   in all  new  installations  of any   magnitude.

   

Turbine Oils

In many turbine installations the oil must  serve  not only the bearings  but  also  the  reduction  gearing and  perhaps the  thrust  elements. Therefore, consideration of this type of lubricant is necessary. The viscosity of the oil used in geared turbines is generally a compromise since the bearings would require a lower viscosity than the gearing. The base oil should be in the range of 300 to 500 SUS at 100 degree F. This oil should be  well refined  so that  it  will  have  long  life  and  so that  any naturally  occurring  compounds which might  contribute  to  emulsions are  removed. All of these points to solvent refined oils.

Alkyl  phenols, such as 2, 6-ditertbutyl – 4 – methyl phenol, or “Ionol” in a  proportion of 0.1 to 1 per cent are  satisfactory  oxidation  inhibitors for  most  turbine  oil formulations.

Rust  inhibitors should  be  of a nature  which  will not  contribute  to  emulsions nor  be  removed  from the oil by water. Or this reason “Lubrizol 850” or “Alox 1832” can be used. The former is effective in concentrations o 0.05 to 0.10 per cent and the latter in amount up to 2.5 per cent.

An  antifoaming  agent,  such  as a dimethyl  silicon polymer, in  a  concentration of about 0.001  per cent, should  be  present  in turbine  oils.

According to Landis et al. the emulsive tendencies of antirust turbine oils can be reduced by the addition of small amounts of aryl sulfonic acids or their salts. A typical composition  consists of : a solvent  refined  oil having  a viscosity  of 350 to 600 SUS  at  100 degree F  and  containing  0.25  per cent  by  weight  of  2, 6 – ditertbutyl -4 – methylphenol; 0.1 per cent  of  phenyl  alpha  naphthylamine; 0.1 per cent  of an  antitrust  agent obtained   by  reacting  oleic  acid  with  triethylenetetramine, in a molar ratio of 1.3  to 1, to  produce an  intermediate  product  which  is  then  reacted  with  triisobutenyl  succinic  acid  anhydride in a molar  ratio of 2.3 to 1; and  0.02 per cent  of sodium  petroleum  sulfonate. As  a  substitute  for  the  last  ingredient, 0.02 per cent  of either barium  or zinc  petroleum  sulfonate  or  0.05 per cent  of  ammonium  petroleum sulfonate, can  be used. The proportion of such demulsifies is critical and an excess defeats the purpose.