Purification of impure oil by centrifugation

Abstract

The present invention relates to methods, apparatus and systems of purifying an impure oil by subjecting the impure oil to a disk stack centrifuge at a rate greater than about 80 gallons per minute, to obtain a purified oil. In particular, the purified oil can have an impurity content of less than about 0.3% by weight, or greater than about 2 fold less than the impurity content of the impure oil. In one embodiment, the present invention utilizes a particular type of dick stack centrifuge referred to as a “disk type nozzle centrifuge”.

1 . A method of purifying an impure oil, wherein the method comprises: 
 subjecting the impure oil to a disk stack centrifuge at a rate greater than about 303 liters per minute (LPM), to thereby obtain a purified oil.    
     
     
         2 . The method of  claim 1 , wherein the disk stack centrifuge is a disk type nozzle centrifuge.  
     
     
         3 . The method of  claim 2 , wherein the method further comprises filtering the impure oil prior to subjecting said impure oil to the disk type nozzle centrifuge.  
     
     
         4 . A method of purifying an impure oil, wherein the method comprises: 
 a) heating the impure oil; and    b) subjecting the heated, impure oil to a disk stack centrifuge at a rate greater than about 303 LPM, to thereby obtain a purified oil.    
     
     
         5 . The method of  claim 4 , wherein the impure oil is heated to a temperature in a range between about 79° C. and about 135° C.  
     
     
         6 . The method of  claim 5 , wherein the impure oil is filtered to remove particles that are greater than about 80 microns.  
     
     
         7 . The method of  claim 5 , further comprising cooling the purified oil.  
     
     
         8 . A method of purifying an impure oil having an impurity content, wherein the method comprises: 
 subjecting the impure oil to a disk stack centrifuge at a rate greater than about 303 LPM, to thereby obtain a purified oil having an impurity content that is less than the impurity content of the impure oil prior to being subjected to the centrifuge.    
     
     
         9 . The method of  claim 8 , wherein the impure oil has an impurity content of greater than about 0.1% by weight.  
     
     
         10 . The method of  claim 9 , wherein the impure oil has an ash content of greater than about 0.1% by weight.  
     
     
         11 . The method of  claim 8 , wherein the purified oil has an impurity content that is greater than about 2 fold less than the impurity content of the impure oil.  
     
     
         12 . A method of purifying an impure oil having an impurity content of greater than about 0.1% by weight, wherein the method comprises: 
 subjecting the impure oil to a disk stack centrifuge at a rate greater than about 303 LPM, to thereby obtain a purified oil having an impurity content that is greater than about 2 fold less than the impurity content of the impure oil prior to centrifugation.    
     
     
         13 . The method of  claim 12 , wherein the purified oil has an impurity content of less than about 0.3% by weight.  
     
     
         14 . The method of  claim 13 , wherein the purified oil has an ash content of less than about 0.3% by weight.  
     
     
         15 . The method of  claim 13 , wherein the purified oil has an aluminum content of less than about 0.03% by weight.  
     
     
         16 . The method of  claim 13 , wherein the purified oil has a silicon content of less than about 0.04% by weight.  
     
     
         17 . A method of purifying an impure oil having an impurity content between about 0.5% by weight and about 0.7% by weight, wherein the method comprises: 
 subjecting the impure oil to a disk stack centrifuge at a rate greater than about 303 LPM, to thereby obtain a purified oil having an impurity content that is less than the impurity content of the impure oil prior to being subjected to the centrifuge and a slurry having an impurity content that is greater than the impurity content of the impure oil prior to being subjected to the centrifuge.    
     
     
         18 . The method of  claim 17 , wherein the purified oil has an impurity content of less than about 0.3% by weight  
     
     
         19 . The method of  claim 17 , wherein the slurry has an impurity content between about 1.0% and about 6.0% by weight.  
     
     
         20 . The method of  claim 19 , wherein the slurry is recycled into purified oil having an impurity content of less than about 0.3% by weight.  
     
     
         21 . The method of  claim 20 , wherein recycling the slurry comprises: 
 subjecting the slurry to a second centrifuge at a rate of between about 38 LPM and about 568 LPM, to thereby obtain a petroleum product having an impurity content of less than about 0.3% by weight.    
     
     
         22 . The method of  claim 21 , wherein the method further comprises mixing the slurry with one or more mixers prior to subjecting the slurry to the second centrifuge.  
     
     
         23 . The method of  claim 22 , wherein after subjecting the slurry to a second centrifuge, recycling the slurry further comprises: 
 subjecting the petroleum product, one or more times, to a disk stack centrifuge at a rate greater than about 303 LPM, to thereby obtain a purified oil having an impurity content of less than about 0.3% by weight.    
     
     
         24 . The method of  claim 23 , wherein the second centrifuge is a decanter centrifuge.  
     
     
         25 . A method for removing impurities from an impure oil having an amount of one or more impurities, wherein the method comprises: 
 subjecting the impure oil to a disk stack centrifuge at a rate greater than about 303 LPM, to thereby obtain an oil having an amount of one or more impurities less than the amount of the one or more impurities prior to centrifugation.    
     
     
         26 . A method for removing inorganic material from an impure oil having an inorganic material content between about 0.5% by weight and about 0.7% by weight, wherein the method comprises: 
 subjecting the impure oil to a disk stack centrifuge at a rate between about 303 LPM and about  1325  LPM, to thereby obtain a purified oil having an inorganic material content greater than about  2  fold less than the inorganic material content of the impure oil prior to centrifugation, and a slurry having an inorganic material content greater than about  2  fold more than the inorganic material content of the impure oil prior to centrifugation.    
     
     
         27 . A method for removing ash from an impure oil having an ash content, wherein the method comprises: 
 subjecting the impure oil to a disk type nozzle centrifuge at a rate between about 303 LPM and about 1325 LPM, to thereby obtain a purified oil having an ash content of less than about 0.3% by weight.    
     
     
         28 . The method of  claim 27 , wherein the method further comprises heating the impure oil prior to subjecting said oil to the disk type nozzle centrifuge.  
     
     
         29 . The method of  claim 28 , wherein the impure oil is heated to between about 79° C. and about 135° C. prior to subjecting said oil to the disk type nozzle centrifuge.  
     
     
         30 . An oil purified by the method of  claim 1 .  
     
     
         31 . An apparatus for purifying impure oil that comprises: 
 a) a first tank for providing impure oil;    b) a pump connected to said tank;    c) a disk stack centrifuge, connected to said pump, wherein the centrifuge excretes a centrate and a slurry;    d) a heat exchanger, located between the centrifuge and the first tank, wherein the heat exchanger heats the oil to a temperature in a range between about 79° C. and about 135° C.; and    e) a second tank, connected to the centrifuge, for receiving the centrate;    wherein the pump provides impure oil to the centrifuge at a rate greater than about 303 LPM.    
     
     
         32 . The apparatus of  claim 31 , further comprises a filter placed between the tank and the centrifuge, wherein the filter removes particles that are greater than about  80  microns.  
     
     
         33 . The apparatus of  claim 32 , further comprises a second heat exchanger, located between the centrifuge and the second tank, wherein the heat exchanger chills the centrate to a temperature in a range between about 93° C. and about 66° C.  
     
     
         34 . An apparatus for purifying impure oil that comprises: 
 a) a first tank for providing oil;    b) a pump connected to said tank;    c) a first centrifuge, connected to said pump, wherein the first centrifuge is a disk stack centrifuge that excretes a centrate and a slurry;    d) a second centrifuge, connected to the first centrifuge so that the second centrifuge receives the slurry from the first centrifuge; wherein the second centrifuge excretes a second centrate and a second slurry;    e) a recirulation means for moving the centrate from the second centrifuge to the first centrifuge; and    f) a second tank, connected to the first centrifuge, for receiving the centrate of the first centrifuge;    wherein the pump provides impure oil to the first centrifuge at a rate greater than about 303 LPM.    
     
     
         35 . The apparatus from  claim 34 , wherein the second centrifuge is a decanter centrifuge.