Process for pyrolysis of glycerol-containing feedstocks

Abstract

A process and apparatus for producing a hydrogen-containing product gas ( 4 ) from a glycerol-containing feedstock ( 1 ). A product gas ( 4 ) is produced from the glycerol-containing feedstock ( 1 ) by separation of undesirable substances (V) and the pyrolysis of glycerol (P).

1 . A process for producing a hydrogen-containing product gas ( 4 ) from a glycerol-containing feedstock ( 1 ), containing impurities, comprising the steps of (a) separating the impurities from the glycerol-containing feedstock ( 1 ) and (b) subjecting the resultant glycerol (P) to pyrolysis to produce a hydrogen-containing product gas. 
   
   
       2 . A process according to  claim 1 , wherein the step of separating of impurities present in the feedstock and/or produced during the process and the step of pyrolysis of glycerol are conducted simultaneously in one process step. 
   
   
       3 . A process according to  claim 1 , wherein the product gas ( 4 ) is obtained from the feedstock ( 1 ) in at least two successive process steps, whereby in each of the process steps, impurities are separated and/or glycerol is reacted by pyrolysis. 
   
   
       4 . A process according to  claim 1 , wherein the pyrolysis (P) is conducted with water and/or steam and/or an oxidizing agent wherein the oxidizing agent is air or oxygen-enriched air or oxygen. 
   
   
       5 . A process according to  claim 1 , wherein impurities present in the feedstock ( 1 ) are separated by distillation (V) and/or thermal drying and/or filtering on activated carbon and/or membrane and/or chromatography and/or ion exchange and/or ion exclusion and/or precipitation. 
   
   
       6 . A process according to  claim 5 , comprising the thermal drying of the feedstock, said thermal drying being conducted at temperatures sufficient to cause at least a partial pyrolysis of the glycerol contained in the feedstock ( 1 ). 
   
   
       7 . A process according to  claim 1 , wherein an aqueous mixture ( 3 ) accumulates during the separating of impurities from the feedstock ( 1 ) in which the separated impurities are present in dissolved and/or suspended form, and subjecting the aqueous mixture to drying in a thermal drying system (G), to obtain a largely anhydrous solid fraction ( 6 ) and a gas fraction ( 7 ). 
   
   
       8 . Apparatus for producing a hydrogen-containing product gas ( 4 ) from a glycerol-containing feedstock ( 1 ), comprising means for separating from the feedstock by contaminants from a feedstock and means for subjecting resultant contaminant-depleted feedstock containing glycerol to pyrolysis (P) of the glycerol. 
   
   
       9 . Apparatus according to  claim 8 , wherein the pyrolysis system comprises means for thermal drying of the feedstock, in which a gas-free and a largely anhydrous solid fraction can be produced from the feedstock, whereby glycerol that is present in the gas fraction is at least partially pyrolyzed based on the temperatures prevailing in the thermal drying means. 
   
   
       10 . Apparatus according to  claim 8 , wherein the pyrolysis system comprising purification means (V) and a downstream pyrolysis reactor (P), whereby a pyrolysis feedstock ( 2 ) can be produced in the purification system from the feedstock ( 1 ) by separation of contaminants and can be reacted in the product gas ( 4 ) in the pyrolysis reactor (P) by pyrolysis. 
   
   
       11 . Apparatus according to  claim 8 , wherein the purification means (V) comprises a vacuum distillation system and/or a thermal drying system and/or a filtering system with activated carbon or membrane and/or a chromatography system and/or an ion exchanger and/or ion exclusion system and/or a precipitation and separation system. 
   
   
       12 . Apparatus according to  claim 8 , wherein comprising means (G) for reducing the water content of waste water comprising material that accumulates when the glycerol-containing feedstock ( 1 ) is purified. 
   
   
       13 . A process according to  claim 1 , comprising providing a crude glycerol feed containing salt impurities from a transesterification reaction
 subjecting said crude glycerol feed to a distillation so as to provide an overhead of purified glycerol and a bottoms of a liquid waste product containing salts   subjecting the purified glycerol to pyrolysis so as to obtain a hydrogen-containing product   passing the liquid waste product containing salts from the distillation to a fluidized bed granulator   branching a stream of pyrolyzed glycerol containing hydrogen into said granulator so as to provide heat for drying, and withdrawing from said granulator granulated salts and a stream comprising dust and primarily gases,   and scrubbing the stream comprising dust and primarily gases with water so as to provide a water stream containing said dust as a bottoms product and an overhead comprising mostly pyrolysis gas and steam.