Carbon fiber reinforced coke from the delayed coker
A number of properties of polygranular carbon bodies can be improved by small quantities of carbon fibers being incorporated in the formulations for production of such bodies. However, it has proven difficult for carbon fibers to be introduced into the green mixture. Therefore, a high-grade coke, preferably needle coke, in accordance with the invention is used to produce the polygranular carbon bodies. This high-grade coke according to the invention contains the carbon fibers simply as a result of being produced in the delayed coker of a refinery. All the main details of the way in which a coke of this type is mixed into the green mixture correspond to the reliably managed processing of other needle cokes.
1. A carbon fiber-reinforced coke, comprising:
a mixture of:
a proportion of cut carbon fibers being surface-oxidized or non-surface-oxidized or stabilized precursor fibers for forming PAN-based carbon fibers, and at least one of the following being true for said cut carbon fibers or stabilized precursor fibers upon entering the delayed coker, said fibers or precursor fibers:
not being provided with a sizing; or
being provided with a sizing selected from the group consisting of sizings for satisfying objectives of various textile processes; or
being provided with a sizing selected from the groups consisting of:
waxes, montan waxes, and waxes produced synthetically by esterification of fatty alcohols with long-chain fatty acids containing 12 to 40 carbon atoms;
polyurethane, phenolic, polyester, and epoxy resins; and
low-viscosity pitches and pitches dissolved in organic solvents;
feedstock for a delayed coking process, said feedstock including a material selected from the group consisting of highly aromatic residues of vacuum distillation, residues of visbreaking, residues of a fluidized catalytic cracking process, residues of thermocracking, residues of ethylene pyrolysis, soft pitches produced from coal coking or by distillation of highly aromatic coal residues;
the mixture having been coked in a delayed coker;
said feedstock, upon entering the delayed coker, containing at most 4% by weight of said cut carbon fibers or at most 8% by weight of said stabilized precursor fibers; and
the coke having a coefficient of thermal expansion with values of at most 0.15×10 −6 K −1 , measured on specimens produced in accordance with DIN 51930 in an extrusion direction and in accordance with DIN 51909.
2. The carbon fiber-reinforced coke according to claim 1 formed as needle coke.
3. The carbon fiber-reinforced coke according to claim 1 , wherein said cut carbon fibers or stabilized precursor fibers, upon entering the delayed coker, are from 1 to 30 mm long.
4. The carbon fiber-reinforced coke according to claim 1 , wherein said waxes are polyolefin waxes based on polyethylene or polypropylene.
5. The carbon fiber-reinforced coke according to claim 1 , wherein the coke is calcined with a calcining device selected from the group consisting of a rotary tube calciner, a rotary plate calciner, a gas calciner, and an electric calciner.
6. The carbon fiber-reinforced coke according to claim 1 , wherein said proportion of carbon fibers is less than 20% by weight of the coke.
7. A carbon product, comprising a polygranular carbon body formed with the carbon fiber-reinforced coke according to claim 1 and containing at least 70% by weight of carbon.
8. The carbon product according to claim 7 , wherein said carbon fiber-reinforced coke is a needle coke.
9. The carbon product according to claim 7 , wherein said polygranular carbon is amorphous carbon or graphitized carbon.
10. The carbon product according to claim 7 formed as a carbon electrode, as a connection piece for a carbon electrode, as a fine-grain graphite and a reactor graphite, as a blast-furnace brick, or as electrodes for aluminum fused-salt electrolysis.
11. A method of producing carbon fiber-reinforced coke, which comprises:
mixing surface-oxidized or nonsurface-oxidized cut carbon fibers or stabilized precursor fibers for forming PAN-based carbon fibers into a flow of incoming feedstock to a delayed coking process to form a mixture, the feedstock being selected from the group of highly aromatic residues of vacuum distillation, of visbreaking, of the fluidized catalytic cracking process, of thermocracking, of ethylene pyrolysis or soft pitches produced from coal coking or by distillation of the highly aromatic coal residues;
at least one of the following being true for the cut carbon fibers or stabilized precursor fibers upon entering the delayed coker, the fibers or precursor fibers:
not being provided with a sizing; or
being provided with a Sizing selected from the group consisting of sizings for satisfying objectives of various textile processes; or
being provided with a sizing selected from the groups consisting of:
waxes, montan waxes, and waxes produced synthetically by esterification of fatty alcohols with long-chain fatty acids containing 12 to 40 carbon atoms;
polyurethane, phenolic, polyester, and epoxy resins; and
low-viscosity pitches and pitches dissolved in organic solvents; and
coking the mixture in a delayed coker;
the feedstock, upon entering the delayed coker, containing at most 4% by weight of the cut carbon fibers or at most 8% by weight of the stabilized precursor fibers; and
the coke having a coefficient of thermal expansion with values of at most 0.15×10 −6 K −1 , measured on specimens produced in accordance with DIN 51930 in an extrusion direction and in accordance with DIN 51909.
12. The method according to claim 11 , which comprises forming carbon fiber containing needle coke.