Process for the production of petroleum tar pitch for use as a binder in the production of electrodes

Abstract

A process for the production of petroleum tar pitch with the using a fresh hydrocarbon feedstock, preheating it, treating the heated feedstock and passing fractionating the treated feedstock into gases, light distillates and a bottom fractionation stream, then dividing the bottom fraction stream into a recycle stream and a cracked fraction stream and using the cracked fraction stream in a reduced pressure distillation tower so that the light cracked fraction is fractionated light vacuum gas oil, heavy vacuum gas oil and a high quality petroleum tar pitch.

What is claimed is: 
     
         1 . A process for the production of petroleum tar pitch comprising:
 a. providing a fresh hydrocarbon feedstock;   b. pre-heating at least a portion of the feedstock in a furnace to a temperature of about 380° to 480° C.;   c. feeding at least a portion of the heated feedstock to a reactor and treating at least a portion of the heated feedstock in the reactor under controlled conditions so as to promote condensation and polymerization reactions;   d. passing at least a portion of the treated feedstock to a fractionating tower wherein at least a portion of the treated feedstock is fractionated into (1) gases, (2) light distillates and (3) a bottom fractionation stream;   e. dividing the bottom fraction stream into a recycle stream and a cracked fraction stream;   f. feeding the cracked fraction stream to a reduced pressure distillation tower wherein the light cracked fraction is further fractionated into (1) light vacuum gas oil, (2) heavy vacuum gas oil and (3) a high quality petroleum tar pitch;   g. recycling the recycled stream and admixing the recycle stream with the fresh feedstock; and   h. mixing the petroleum tar pitch with a refining element in the form of anode grade coke, to create a petroleum tar pitch product.   
     
     
         2 . A process according to  claim 1  wherein the feedstock is a highly aromatic hydrocarbon selected from the group consisting of catalytic cracking decanted oil, lubricant extract, Heavy Coker Gasoil (HCGO), Heavy Vacuum Gasoil (HVGO) and mixtures thereof and has the following composition and properties:
 [Density@15° C., (gr/cc) 0.8-1.15 
 Solids Content, (wt. %) 0-0.1 
 Aromatics, (wt. %) 54-85]. 
 
     
     
         3 . A process according to  claim 1  wherein the light vacuum gas oil has the following properties:
 [ASTM D-86 Initial Boiling Point, ° C. 170-220 
 ASTM D-86 Final Boiling Point, ° C. 300-360 
 API Gravity 18-28 
 Aromatics, wt. % 45-80]. 
 
     
     
         4 . A process according to  claim 1  wherein the heavy vacuum gas oil has the following properties:
 [ASTM D-1160 Initial Boiling Point, ° C. 250-320 
 ASTM D-1160 Final Boiling Point, ° C. 450-520 
 API Gravity 0-9 
 Aromatics, wt. % 45-95]. 
 
     
     
         5 . A process according to  claim 1  wherein the petroleum tar pitch has the following properties:
 [Conradson Carbon, (wt. %) 40-60 
 Density@15° C., (gr/cc) 1.20-1.25 
 Mettler Softening Point, (° C.) 100-125 
 Quinoline Insoluble, (wt. %) 0-10]. 
 
     
     
         6 . A process according to  claim 1  wherein the refining element added is anode grade coke and it is added in an amount of between 5 to 20 wt. % of the petroleum pitch. 
     
     
         7 . A process according to  claim 1  wherein the finely divided anode grade coke has the following properties:
 [Average Particle Size, microns 12-110 
 Apparent Bulk Density, gr/cc 0.46-0.65 
 Water Content, wt. % 0-0.2 
 Oil Absorption, cc/100 gr 60-75]. 
 
     
     
         8 . A process according to  claim 1  wherein the petroleum tar pitch product is delivered to a finishing station to be shaped. 
     
     
         9 . A process according to  claim 1  wherein at least a portion of the feedstock is filtered to produce a feedstock having a solid content of 100 ppmw. 
     
     
         10 . A process according to  claim 9  wherein the filtering is done by centrifugal, electrostatic or mechanical techniques. 
     
     
         11 . A process according to  claim 9  wherein the filtering removes at least 99% of solids. 
     
     
         12 . A process according to  claim 9  wherein the filtered feedstock has the following composition and properties:
 [Conradson Carbon, (wt. %) 0-7 
 Density@15° C., (gr/cc) 0.8-1.1 
 Solids Content (wt %) 0-0.01 
 Aromatics, (wt. %) 54-85]. 
 
     
     
         13 . A process according to  claim 9  wherein the filtered feedstock is heated to a temperature of between 380 and 480° C. to provide a heated feedstock. 
     
     
         14 . A process according to  claim 13  wherein the heated feedstock is passed to a soaker reactor, plug flow reactor or batch reactor, and wherein the feedstock is treated in the reactor at condensation and polymerization conditions to provide a treated feedstock. 
     
     
         15 . A process according to  claim 14  wherein the conditions include a temperature between 360 and 460° C., a pressure between 1480 and 1825 kpA, the conditions are oxygen free and inert and are held between 0.25 and 5 hours. 
     
     
         16 . A process according to  claim 14  wherein the treated feedstock is passed to a fractionating tower wherein the treated feedstock is fractionated into (1) gases, (2) light distillates and (3) a bottom stream. 
     
     
         17 . A process according to  claim 1  wherein step (d) takes place under the following conditions:
 [Temperature, ° C. 330-430 
 Pressure, kPa 101-850 
 in an inert environment and substantially oxygen free]. 
 
     
     
         18 . A process according to  claim 16  wherein the treated feedstock is fractionated to yield:
 2 to 8 wt. % C 4 -gases 
 3 to 8 wt. % light distillates having an ASTM D-86 cut point of between 92° C. and 220° C. based on fresh feed and a bottom stream. 
 
     
     
         19 . A process according to  claim 16  wherein the bottom stream is divided into a recycle stream and a cracked fraction bottom stream. 
     
     
         20 . A process according to  claim 19  wherein the cracked fraction bottom stream has the following composition and properties:
 [Conradson Carbon, (wt. %) 10-18 
 Density@15° C., (gr/cc) 1.1-1.15 
 Solids Content, (wt. %) 0-0.01 
 Aromatics, (wt. %) 70-95 
 Softening Point, (° C.) <25]. 
 
     
     
         21 . A process according to  claim 19  wherein the recycle stream is admixed with the filtered feedstock in a preferred ratio of between 2:1 and 3:1 by volume of recycle stream to fresh feedstock. 
     
     
         22 . A process according to  claim 19  wherein the recycle stream is mixed with the filtered feedstock. 
     
     
         23 . A process according to  claim 19  wherein the recycle stream is mixed with the filtered feedstock in a ratio of up to 3:1 by volume recycle stream to fresh feedstock. 
     
     
         24 . A process according to  claim 19  wherein the cracked bottom stream is further fractionated to yield Light Vacuum Gas Oil, Heavy Vacuum Gas Oil and a high quality petroleum tar pitch. 
     
     
         25 . A process according to  claim 24  wherein the cracked bottom stream is further fractionated under the following conditions: bottom fractionator temperature 300-380° C., 0.3-15 kPa pressure, in an inert and a substantially oxygen free environment. 
     
     
         26 . A process according to  claim 24  wherein the cracked bottom stream is further fractionated to yield the following products:
 [ASTM D-1160 End Point Wt. % 
 Light Vacuum Gas Oil 300-360° C. 15-25 
 Heavy Vacuum Gas Oil 450-570° C. 30-50 
 Petroleum Tar Pitch 15-50]. 
 
     
     
         27 . A process according to  claim 24  wherein the Heavy Vacuum Gas Oil is recycled into the filtered feedstock in a ratio from about 0.25:1 by volume recycle stream to fresh feedstock. 
     
     
         28 . A process according to  claim 24  wherein the heavy vacuum gas oil is recycled into the filtered feedstock in a ratio of about between 0.5:1 to 0.8:1 by volume recycle stream to fresh feedstock. 
     
     
         29 . A process according to  claim 1  wherein the refining element further comprises fine divided carbon black. 
     
     
         30 . A process according to  claim 1  wherein the refining element further comprises anode grade coke and low metals and sulfur content coke.