GB1576066A - Manufacture of binder pitch - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO THE MANUFACTURE OF BINDER PITCH (71) We, THE LUMMUS COMPANY, a Corporation organised and existing under the laws of the State of Delaware, United States of America, of 1515 Broad Street, Bloomfield, New Jersey, 07003, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to the preparation of binder pitch, and in particular to the preparation of binder pitch by producing an improved feedstock from which the binder pitch is prepared.

Binder pitch in accordance with the invention may be especially useful in the formation of carbon electrodes.

Our pending patent application No.

42099/75, filed October 14, 1975, (Serial No.

1,521,553) describes the preparation of a feedstock of substantially constant quality for the production of needle coke and/or high quality carbon black. In accordance with this pending Application, there is provided a process for converting hydrocarbon materials containing pyrolysis fuel oils into uniform feedstocks of substantially constant quality, which comprise subjecting said hydrocarbon materials containing pyrolysis fuel oils to the following steps prior to the use thereof in coke or carbon black production:: a) adding sulphur to the materials containing pyrolysis fuel oil prior to their introduction into a soaking drum, b) maintaining of the materials containing pyrolysis fuel oil at above 4500F for at least about 5 minutes in a soaking zone, c) heating the thus treated materials to a temperature of 8500F to 11000F for a residence time from 8 seconds to 110 seconds and at an outlet pressure of from 350 to 600 psig, and d) recovering a uniform quality feedstock.

The present invention seeks to provide an improvement on the process of the above pending Application, which makes it possible to convert efficiently and speedily the feedstock so obtained to carbon electrode binder pitch.

According to this invention there is provided a process for the preparation of binder pitch from hydrocarbon materials containing pyrolysis fuel oils which comprises subjecting said hydrocarbon materials containing pyrolysis fuel oils to the following steps: a) adding sulphur to the materials containing pyrolysis fuel oil prior to their introduction into a soaking zone, b) maintaining of the materials containing pyrolysis fuel oil at above 450"F for at least 5 minutes in a soaking zone, c) heating the thus treated materials to a temperature of 850"F to 11000F for a residence time from 8 seconds to 110 seconds and at an outlet pressure of from 350 to 600 psig, d) recovering a feedstock of substantially constant quality, and e) cooling and depressurizing said feedstock to a pressure of from 10 to 100 psig and a temperature of from 500 to 7500F and distilling the liquid from the feedstock to provide a binder pitch residue.

Advantageously, the added sulphur is in the form of elemental sulphur.

Preferably a process in accordance with the invention also comprises a quenching step to quench the depressurized pyrolysis fuel oil in order to reduce or arrest further polymerization.

According to another aspect of this invention there is provided a process as claimed in any one of claims 1--5 and 7-9 of pending application 42099/75 (Serial No.

1521553) comprising the further steps of cooling and depressurizing said feedstock to a pressure of from 10 to 100 psig and at temperature of from 500 to 7500F and distilling the liquid from the feedstock to provide a binder pitch residue.

The invention also relates to the product of such a process.

Binder pitch is used for the manufacture of electrodes from calcined coke. These electrodes are used in metallurgical processes such as steel furnaces and aluminium reduction. For this purpose, binder pitch is combined with calcined coke in order to bind the coke particles and to mould 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 baked, 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; such a preparation has not been possible in the past. It has been found that a process of the invention permits the preparation of binder pitch from a petroleum base to meet the stringent requirements in steel'furnaces and aluminium reduction.

In order that the invention may be more readily understood and so that further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawing which is a schematic flow diagram of a process in accordance with the present invention.

Referring now to the drawing, 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 to the illustrated apparatus through line 101. A slipstream of the feed is passed through a pot 102 containing elemental sulphur wherein sufficient sulphur is dissolved in the slipstream so that upon blending with the main stream, the sulphur content will be from about 30 to about 200 ppm. The sulphur-containing pyrolysis fuel oil is then passed through heat exchanger 103 to effect heating thereof, with the heated oil in line 104 being introduced into a soaking drum 105 wherein the pyrolysis fuel oil is maintained at a temperature above 450"F for at least 5 minutes. Vapour from the soaking drum 105 passes into a fractionator 106 through line 107.

The liquid from soaking drum 105 is withdrawn through a line 108 and introduced under pressure (for example, by a pump, not shown) into a heater 109 wherein the liquid is heated at a temperature of 850"F to 11000F and at a pressure of from 350 to 600 psig for a residence time of 8 to 110 seconds.

The treated fuel oil is withdrawn from the heater 109 through line 111 as a feedstock of substantially constant quality and is cooled to a temperature of from 5000F to 7500 F, preferably from about 5500F to about 700"F, 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 of from 10 psig to 100 psig, preferably from about 25 psig to about 40 psig (a pressure which is substantially equal to that prevailing in the fractionating tower), by passage through a control valve 114 and the stream introduced into the fractionating tower 106 through line 1l5.

The fractionator 106 is operated to recover binder pitch as bottoms through line 116; a distillate oil sidestream through line 117; and gasoline 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 to the effluent from heater 109.

The invention will now be further illustrated by means of the following example: Example A pyrolysis fuel oil having 25-50 parts per million of elemental sulphur added thereto was charged to a soaking tank and held there at a temperature of about 5000F for a period of about 15 minutes. The lighter boiling liquid was drawn off as a vapour, and the higher boiling liquid, after the 15 minutes soaking period, was pumped to a furnace and heated to a temperature of about 900"F for a period of 17 seconds and an outlet pressure of 350 psig. After cooling and pressure reduction 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 Point, OF 223 Viscosity, Saybolt Furol, sec. at 3600F 311 Saybolt Furol, sec. at4000F 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 following properties:: Gravity, "API -6.68 Softening Point, "F 232 Viscosity, Saybolt Furol, sec. at 3000F 2122 Saybolt Furol, sec. at 3500F 440 Saybolt Furol, sec. at 4000 F 105 (extrapolated) A comparison of the pitches indicates that the pitch produced in accordance with the present invention has an increased aromaticity, as evidenced by a lower API gravity and a lower viscosity.

WHAT WE CLAIM IS: 1. A process for the preparation of binder pitch from hydrocarbon materials containing pyrolysis fuel oils which comprises subjecting said hydrocarbon materials containing pyrolysis fuel oils to the following steps: a) adding sulphur to the materials containing pyrolysis fuel oil prior to their introduction into a soaking zone, b) maintaining of the materials containing pyrolysis fuel oil at above 450"F for at least 5 minutes in a soaking zone, c) heating the thus treated materials to a temperature of 850"F to 1 1000F for a residence time from 8 seconds to 110 seconds and at an outlet pressure of from 350 to 600 psig, d) recovering a feedstock of substantially constant quality, and e) cooling and depressurizing said feedstock to a pressure of from 10 to 100 psig and a temperature of from 500 to 750 F and distilling the liquid from the feedstock to provide a binder pitch residue.

2. A process according to Claim 1, wherein said sulphur is in the form of elemental sulphur.

3. A process according to Claim 1 or Claim 2 which includes the step of quenching the depressurized pyrolysis fuel oil to reduce further polymerization.

4. A process according to any one of the preceding claims wherein the feedstock is cooled to a temperature of from 550"F to 700"F.

5. A process according to any one of the preceding claims wherein the feedstock is depressurized to a pressure of from 25 to 40 psig.

6. A process substantially as herein described with reference to the accompanying drawings.

7. A process substantially as herein described in the Example.

8. A process as claimed in any one of claims 1--5 and 7-9 of pending application 42099/75 (Serial No. 1,521,553) comprising the further steps of cooling and depressurizing said feedstock to a pressure of from 10 to 100 psig and at temperature of from 500 to 7500F and distilling the liquid from the feedstock to provide a binder pitch residue.

9. A product of a process according to any one of the preceding claims.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. Saybolt Furol, sec. at 3000F 2122 Saybolt Furol, sec. at 3500F 440 Saybolt Furol, sec. at 4000 F 105 (extrapolated) A comparison of the pitches indicates that the pitch produced in accordance with the present invention has an increased aromaticity, as evidenced by a lower API gravity and a lower viscosity. WHAT WE CLAIM IS:

1. A process for the preparation of binder pitch from hydrocarbon materials containing pyrolysis fuel oils which comprises subjecting said hydrocarbon materials containing pyrolysis fuel oils to the following steps: a) adding sulphur to the materials containing pyrolysis fuel oil prior to their introduction into a soaking zone, b) maintaining of the materials containing pyrolysis fuel oil at above 450"F for at least 5 minutes in a soaking zone, c) heating the thus treated materials to a temperature of 850"F to 1 1000F for a residence time from 8 seconds to 110 seconds and at an outlet pressure of from 350 to 600 psig, d) recovering a feedstock of substantially constant quality, and e) cooling and depressurizing said feedstock to a pressure of from 10 to 100 psig and a temperature of from 500 to 750 F and distilling the liquid from the feedstock to provide a binder pitch residue.

2. A process according to Claim 1, wherein said sulphur is in the form of elemental sulphur.

3. A process according to Claim 1 or Claim 2 which includes the step of quenching the depressurized pyrolysis fuel oil to reduce further polymerization.

4. A process according to any one of the preceding claims wherein the feedstock is cooled to a temperature of from 550"F to 700"F.

5. A process according to any one of the preceding claims wherein the feedstock is depressurized to a pressure of from 25 to 40 psig.

6. A process substantially as herein described with reference to the accompanying drawings.

7. A process substantially as herein described in the Example.

8. A process as claimed in any one of claims 1--5 and 7-9 of pending application 42099/75 (Serial No. 1,521,553) comprising the further steps of cooling and depressurizing said feedstock to a pressure of from 10 to 100 psig and at temperature of from 500 to 7500F and distilling the liquid from the feedstock to provide a binder pitch residue.

9. A product of a process according to any one of the preceding claims.