CA1063960A

CA1063960A - Binder pitch from petroleum-base stock

Info

Publication number: CA1063960A
Application number: CA274,365A
Authority: CA
Inventors: Harold Unger; Morgan C. Sze; Thomas M. Bennett
Original assignee: Lummus Co
Current assignee: CB&I Technology Inc
Priority date: 1976-03-22
Filing date: 1977-03-21
Publication date: 1979-10-09
Also published as: DE2711635A1; JPS5747954B2; SE433085B; FR2345506B2; JPS52141828A; FR2345506A2; GB1576066A; SE7703225L; DE2711635C2; IT1116718B

Abstract

ABSTRACT

A process for the preparation of binder pitch is described. The process includes cooling and depressurizing treated pyrolysis fuel oil to a pressure of from 10 to 100 psig and at temperature of from 500 to 750°F and distilling the liquid from the pyrolysis fuel oil to provide a binder pitch residue.

Description

018-l ~.()6396 This invention relates to the preparation of carbon elec-trode binder pitch, and in particular to the preparation of carbon electrode binder pitch by producing an improved feedstock from which the carbon electrode binder pitch is prepared.
Our pending patent application No. 236,849 , filed October 1, 1975 , describes the preparation of a constant quality feedstock for the production of needle coke and/or high quality carbon black. In accordance with this Application, the feedstocks are prepared by converting hydrocarbon materials contain-ing unstable components by: (a) the addition of sulphur into the pyrolysis fuel oil prior to introduction into a soaking tank or drum, (b) the maintenance of the pyrolysis fuel oil at above 450F
for at least 5 minutes in the soaking tank, and (c) heating the pyrolysis fuel oil at a te~perature of about 850 to about 1100F
for a residence time from between 8 seconds and 110 seconds and at an outlet pressure of from 350 to about 600 psig.
The present invention is an improvement on the process of the above Application, which makes it possible to convert effi-cient--ly and speedily the feedstock so obtàined to carbon electrode binder pitch. The present improvement generally comprises the fractionation of the pyrolysis fuel oil and the direct quenching with a pressurized stream.
More particularly, the present invention provides a process for the preparation of binder pitch, which comprises cooling and depressurizing treated pyrolysis fuel oil to a pressure of from 10 to 100 psig and a temperature from 500 to 750F and distilling the liquid from the pyrolysis fuel oil to provide a binder pitch residue.
The inventibn further provides, as an additional aspect of the invention, the inclusion of a quenching step to quench the depressurized pyrolysis fuel oil in order to reduce or arrest further polymerization.

~ .

.~ la63s60 Binder pitch is used for the manufacture of electrodes from calcined coke. These electrodes are used in metallurgical processes such as steel furnaces and aluminum reduction, For this purpose, binder pitch is combined with calcined coke in order to blnd the coke particles and to mold them to the desired electrode shape. They can then be baked, in the course of which the pitch is converted to coke.
It is therefore desirable for the binder pitch to have the following properties:
1. Sufficient fluidity to wet and penetrate the coke particles at temperatures which can be readily attained with steam obtained from power stations;

2. A relatively high coke yield when the binder pitch is pyrolyzed or when the electrode is bake~,and

3 High aromaticity which would produce a coke of the needle type.
The present invention is particularly concerned with the preparation of binder pitch from a petroleum base which could not hitherto be satisfactorily prepared. It is the advantage of the process of the invention that it permits the preparation of binder pitch from a petroleum base to meet the stringent requirements in steel furnaces and aluminum reduction.
The invention will now be particular~illustratedby Fig. 1 of the drawings.
Referring now to Fig. 1, a pyrolysis fuel:oil, such as the heavy high boiling fraction obtained in the cracking of petroleum distillates in the presence of steam to produce olefins, is introduced into the unit through line 101.
slipstream of the feed is passed through a pot 102 containing elemental sulfur wherein sufficient sulfur is dissolved in the slipstream so that upon blending with the main stream, the sulfur content will be from about 30 to about 200 ppm.- The sulfur containing pyrolysis fuel oil is then passed through ~063960 i heat exchan~er 103 to effect heatin~ thereof, with the heated oil in line 104 bein~ introduced into soaking drum 105 wherein the pyrolysis fuel oil is treated at the conditions hereinabove described. Vapor from the soaking drum 105 passes into the fractionator 106 through line 107.
The liquid from soaking drum 105 is withdrawn through ¦ .
line 108 and introdt~ced under pressure (for example, by a pump, not shown) into a heater 109 wherein the liquid is heated at the temperatures and pressures hereinabove described to pro-duce a treated pyrolysis fuel oil having the hereinabove described characteristics.
The treated fuel oil is withdrawn from the heater 109 through line 111 and is cooled to a temperature in the order of from about 500F to about 750F, preferably from about 550F
C to about 700F, by direct quenching with.a pressurized stream in line 112; in particular, gasoline, obtained from fractionator 106. The cooled combined stream is then depressurized to a pressure in the order of from about 10 psig to about 100 psig, preferably from about 25 psig to about 40 psig (a pressure essentially that prevailing in the fractionating tower), by passage ~hrough a control valve 114 and introduced into the fractionating tower 106 through line 115.
The fractionator 106 is operated to recover binder pitch as bottoms through line 116; a distillate oil sidestream through line 117; and gasollne and gas overhead through line 118. A portion of the gasoline recovered from.the overhead is pressurized and employed in line 112 to effect quenching of the effluent from heater 109.
~ The invention will now be further illustrated by means of the following example:
Example A pyrolysis fuel oi.l having 25-50 parts per million, as elemental sulfur, added thereto was charged to a soaking tank and held there at a temperature of about 500F fo~ a period of about 15 minutes. The lighter boiling liquid was drawn off as a vapor, and the higher boiling liquid, after the 15 ~ 063960 minute soaking period, was p~mped to a furnace and heated to a temperature of about 900F for a period of 17 seconds and an outle~ pressure of ~50 psig. After cooling-and-pressure redu(~tion followed by flashing of lighter materials, the liquid remaining, comprising a 99.6% yield, based on the original charge, was distilled leaving a residue of 31.4 weight percent having the following properties:
Gravity, API -9.43 Softening Po;nt, F 223 Viscosity, Saybolt Furol, sec. at 360F 311 " " , sec. at 400F 61.5 Distillation of a pyrolysis fuel oil, without treatment as hereinabove described, which will leave a residue or pitch of 34.7 weight percent resulted in a pitch having the follow-C ing properties:
Gravity, API -6.68 Softening Point, F 232 Viscosity, Saybolt Furol, sec. at 300F 2122 -" . " sec. at 350F 440 " " , sec. at 400F 105 (extrapolated) A comparison of the pitches indicates that the pitch produced in accordance with the present invention has an in-creased aromaticity, as evidenced by a lower API gravity and a lower viscosity.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED OR DEFINED AS FOLLOWS:

1. A process for the preparation of binder pitch, which comprises cooling and depressurizing treated pyrolysis fuel oil to a pressure of from 10 to 100 psig and at tempera-ture of from 500 to 750°F and distilling the liquid from the pyrolysis fuel oil to provide a binder pitch residue.

2. The process claimed in Claim 1, which includes the step of quenching the depressurized pyrolysis fuel oil to reduce further polymerization.