Method and system for producing refined hydrocarbons from waste plastics

Abstract

Embodiments of the present disclosure relate to a method and system for producing refined hydrocarbons from waste plastics. The method and system for producing refined hydrocarbons from waste plastics according to the embodiments of the present disclosure may minimize formation of an ammonium salt (NH 4 Cl) and may prevent an adhesion phenomenon of impurity particles in a reactor in a refining process of waste plastic pyrolysis oil containing impurities including chlorine and nitrogen. In addition, refined hydrocarbons having excellent quality due to a significantly low content of impurities and a significantly low content of olefins may be produced.

1 . A method for producing refined hydrocarbons from waste plastics, the method comprising:
 a pyrolysis operation introducing waste plastics into a pyrolysis reactor and pyrolyzing the waste plastics to produce pyrolysis gas;   an oil production operation producing waste plastic pyrolysis oil by introducing the pyrolysis gas into a hot filter filled with a neutralizing agent;   a dehydration operation applying a voltage to a first mixed solution comprising the waste plastic pyrolysis oil, washing water, and a demulsifier to provide a dehydrated solution;   a first hydrotreating operation hydrotreating a second mixed solution comprising the dehydrated solution and a sulfur source to produce a first stream comprising refined oil; and   a gas-liquid separation operation separating the first stream to a gas stream comprising hydrogen and a second stream comprising the refined oil; and   a second hydrotreating operation hydrotreating the refined oil in the second stream.   
     
     
         2 . The method of  claim 1 , wherein in the dehydration operation, the waste plastic pyrolysis oil is in a greater volume than the washing water. 
     
     
         3 . The method of  claim 2 , wherein in the dehydration operation, the waste plastic pyrolysis oil and the washing water are in the first mixed solution at a volume ratio of 1:0.001 to 1:0.5. 
     
     
         4 . The method of  claim 1 , wherein in the dehydration operation, the waste plastic pyrolysis oil and the demulsifier are in the first mixed solution at a volume ratio of 1:0.000001 to 1:0.001. 
     
     
         5 . The method of  claim 1 , wherein the voltage is applied as an alternating current or a combination of an alternating current and a direct current. 
     
     
         6 . The method of  claim 1 , wherein the voltage is applied through at least one pair of vertical electrodes. 
     
     
         7 . The method of  claim 1 , further comprising, after the application of the voltage in the dehydration operation, removing a rag layer from the dehydrated solution. 
     
     
         8 . The method of  claim 1 , wherein the dehydration operation is performed under a temperature condition of 20° C. to 300° C. 
     
     
         9 . The method of  claim 1 , wherein a ratio of a content of moisture in the waste plastic pyrolysis oil to a content of moisture in the dehydrated solution is 1:0.0001 to 1:0.9. 
     
     
         10 . The method of  claim 1 , wherein the dehydrated solution is additionally dehydrated by condensation of moisture. 
     
     
         11 . The method of  claim 1 , wherein a weight ratio of nitrogen to chlorine in the second mixed solution is 1:1 to 1:10. 
     
     
         12 . The method of  claim 1 , wherein the sulfur source includes sulfur-containing oil. 
     
     
         13 . The method of  claim 12 , wherein the sulfur-containing oil is included in an amount of less than 0.5 parts by weight with respect to 100 parts by weight of the dehydrated solution. 
     
     
         14 . The method of  claim 1 , wherein the sulfur source includes one or more sulfur-containing organic compounds selected from the group consisting of a disulfide-based compound, a sulfide-based compound, a sulfonate-based compound, and a sulfate-based compound. 
     
     
         15 . The method of  claim 1 , wherein the first hydrotreating operation is performed in the presence of a molybdenum-based hydrotreating catalyst. 
     
     
         16 . The method of  claim 15 , wherein the molybdenum-based hydrotreating catalyst is a catalyst in which molybdenum metal, or molybdenum and one or more of nickel, cobalt, and tungsten are supported on a support. 
     
     
         17 . The method of  claim 1 , wherein the first hydrotreating operation is performed under a pressure condition of 50 bar to 150 bar. 
     
     
         18 . The method of  claim 1 , further comprising, after the gas-liquid separation operation, washing the gas stream with water. 
     
     
         19 . The method of  claim 1 , wherein the refined oil is distilled before the second hydrotreating operation. 
     
     
         20 . The method of  claim 1 , wherein the second hydrotreating operation hydrotreats mixed oil obtained by mixing the refined oil and petroleum hydrocarbons.