Method for Treating Hydrocarbon Effluent from Hydrothermal Liquification of Plastic Waste

Abstract

A method for treating effluent from hydrothermal liquification of feedstock that contains plastic oil, pyrolysis oil, synthetic oil or hydrocarbons distillates in a plastic recycle process using supercritical water as a reaction medium into a finished liquid hydrocarbon fuel by removing impurities such as i.e. silicon, chlorides, metals, heteroatoms, etc., in a pre-treatment zone and may be passed into a feed drum or a continuous mixed settler vessel. The feed is introduced into a hydrogen atmosphere reactor. The reactor effluent is passed to a separator for extracting product mixture by addition of make-up or recycled hydrogen to the separator. The overhead product mixture is water washed to remove sour water or salt. The separator effluent is passed to a distillation section for extracting a liquid fuel product stream. A portion of the hydro processing product stream may be recycled to the feed drum or the continuous mixed settler vessel, which reduces concentration of diolefins.

I/We claim: 
     
         1 . A method for treating hydrocarbon effluent from hydrothermal liquification of plastic waste into a clean liquid fuel product comprising:
 a) removing impurities in a hydrocarbon effluent stream through a pre-treatment section to yield a pre-treated hydrocarbon effluent;   b) passing the pre-treated hydrocarbon effluent to a feed drum;   c) feeding the pre-treated hydrocarbon effluent to at least one reactor in the presence of hydrogen at a temperature between 18° and 500° C., and a hydrogen partial pressure between 20.0 to 180.0 barg to obtain a hydrogenated effluent;   d) passing the reactor effluent to a separator consists of hot high pressure and a cold high pressure separators;   e) introducing a make-up or recycled hydrogen along with the reactor effluent to the hot high pressure separator at a temperature 180 to 380° C., and a hydrogen partial pressure between 15.0 to 170.0 barg;   f) passing overhead stream of the hot high pressure separator with water to the cold high pressure separator;   g) removing salt dissolved sour water from the cold high pressure separator;   h) passing the effluent to a distillation section;   i) recycling a portion of hydro treated product to the feed drum to reduce concentration of diolefins.   
     
     
         2 . The method for treating effluent from hydrothermal liquification to a clean liquid fuel as claimed in  claim 1  wherein the feed is a Plastic Oil, Pyrolysis oil, synthetic oil or distillate from plastic recycle process. 
     
     
         4 . The method for treating effluent from hydrothermal liquification to a clean liquid fuel as claimed in  claim 1  wherein the reactor is in hydrogen atmosphere reactor, Guard bed or trickle bed. 
     
     
         5 . The method for treating effluent from hydrothermal liquification to a clean liquid fuel as claimed in  claim 1  wherein the product is suitable for use as a transportation fuel or stream cracker feedstock. 
     
     
         6 . The method for treating effluent from hydrothermal liquification to a clean liquid fuel as claimed in  claim 1 , wherein the method further comprising:
 passing the pre-treated hydrocarbon effluent to a continuous mixed settler vessel; and   recycling a portion of hydro treated product to the continuous mixed settler vessel to reduce concentration of diolefins.   
     
     
         7 . The method for treating effluent from hydrothermal liquification to a clean liquid fuel as claimed in  claim 6 , wherein the continuous mixed settler vessel is a vertical vessel having a conical bottom to enable removal of fine solid particles. 
     
     
         8 . A system for treating effluent from hydrothermal liquification to a clean liquid fuel product comprising:
 a) a contaminant removal unit, which reduces impurities from a hydrothermal liquification effluent;   b) a feed drum, which receives low severe impurities feed stock from the contaminant removal unit;   c) a reactor, which receives low impurity feed stock from the feed drum treated with fresh or make-up hydrogen;   d) a separator unit consists of a Hot and Cold high-pressure separators, which receives the reactor effluent with fresh or make-up hydrogen and water to convert into liquid fuel product and sour water;   e) a stripping unit, which receives the separator effluent for extracting a clean liquid fuel product stream, the sour water and off-gas.   
     
     
         9 . The system for treating effluent from hydrothermal liquification to a clean liquid fuel as claimed in  claim 8 , further comprising recycling a portion of the liquid fuel product from separator to the feed drum, which reduces concentration of diolefins. 
     
     
         10 . The system for treating effluent from hydrothermal liquification to a clean liquid fuel as claimed in  claim 8 , further comprising:
 a continuous mixed settler vessel that receives low severe impurities feed stock from the contaminant removal unit and to recycle a portion of the liquid fuel product from the separator unit which reduces concentration of diolefins.