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 chloride 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. The method and system for producing refined hydrocarbons according to the present disclosure may have excellent refining efficiency and may implement a long-term operation of a process because a catalyst used in the process is prevented from being deactivated, and may produce lightened and refined hydrocarbons having a low content of impurities and a low content of olefins from waste plastics.

What is claimed is: 
     
         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 obtained by mixing the waste plastic pyrolysis oil, washing water, and a demulsifier to dehydrate the first mixed solution;   a hydrotreating operation hydrotreating a second mixed solution obtained by mixing the first mixed solution dehydrated in the dehydration operation and a sulfur source to produce refined oil from which impurities are removed; and   a dewaxing operation dewaxing the refined oil from which impurities are removed.   
     
     
         2 . The method of  claim 1 , wherein in the dehydration operation, the waste plastic pyrolysis oil is mixed 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 mixed 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 mixed 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 first mixed 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 first mixed solution dehydrated in the dehydration operation is 1:0.0001 to 1:0.9. 
     
     
         10 . The method of  claim 1 , wherein the first mixed solution in the dehydration operation 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 first mixed solution dehydrated in the dehydration operation. 
     
     
         14 . The method of  claim 1 , wherein the sulfur source includes one or two or more sulfur-containing organic compounds selected from 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 hydrotreating 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 a molybdenum-based metal, or a metal including one or two or more selected from nickel, cobalt, and tungsten, and a molybdenum-based metal are supported on a support. 
     
     
         17 . The method of  claim 1 , wherein the hydrotreating operation is performed under a pressure condition of 50 bar to 150 bar. 
     
     
         18 . The method of  claim 1 , further comprising, after the hydrotreating operation, subjecting a stream including the refined oil from which impurities are removed to gas-liquid separation and then washing the gas-liquid separated stream with water. 
     
     
         19 . The method of  claim 1 , wherein the dewaxing operation dewaxes a refined fraction separated by distilling the refined oil from which impurities are removed. 
     
     
         20 . The method of  claim 1 , wherein the dewaxing operation dewaxes mixed oil obtained by mixing the refined oil from which impurities are removed and petroleum hydrocarbons.