Coking - the process of processing liquid or solid fuels by heating without oxygen. The decomposition of fuels produces a solid product — petroleum or coal coke and volatile products. The main amount of coke is obtained from coal  .
The production of coal coke arose in the 18th century  when it was necessary to replace the increasingly scarce charcoal for blast furnaces . The first industrial coke smelting was performed in Great Britain in 1735. By 198Z, global coke production amounted to about 360 million tons  .
A widespread technological process consisting of the following stages: preparation for coking, actually coking, trapping and processing of volatile products  .
The preparation includes the enrichment (for removal of mineral impurities) of low-sulfur, low-ash, coking coal, grinding to grains about 0.3 mm in size, mixing several grades of coal, drying the resulting mixture.
For coking, the charge is loaded into a slit-like coke oven (width 400–450 mm, volume 30–40 m 3 ). The channels of the side walls of furnaces lined with refractory bricks are heated by the combustion products of gases: coke (most often), blast-furnace , generator , their mixtures, etc.
The duration of heating is 14-16 hours. The process temperature is 900–1050 ° C. The resulting coke (75–78% by weight of the original coal), in the form of a so-called “coke cake” (baked plastic mass), is pushed out by special machines (“coke pushers”) into railway cars, in which it is cooled (“extinguished”) with water or gas ( nitrogen ).
At 250 degrees Celsius, water evaporates from coal, carbon monoxide and carbon dioxide evaporate, hydrocarbons disappear at 350 degrees, nitrogen and phosphorus compounds evaporate, sintering occurs at 500 degrees, semi-coke is formed at 700 degrees, and coke is formed more and coke  .
Gas-vapor mixture of evolved volatile products (up to 25% by weight of coal) is discharged through the gas collector for capture and processing . For separation, volatile products are cooled by spraying sprayed water (from 70 ° C to 80 ° C) - most of the resins are separated from the vapor phase, further cooling of the vapor-gas mixture is carried out in shell-and-tube refrigerators (up to 25-35 ° C). The condensates are combined and, by settling, they emit over- resinous water and coal tar . Then the crude coke oven gas is successively purified from NH 3 and H 2 S, washed with absorbing oil (to trap raw benzene and phenol ), and sulfuric acid (to trap pyridine bases). Purified coke oven gas (14–15% by weight of coal) is used as a fuel for heating a coke oven battery and for other purposes.
From over-resin water (9-12% by weight of coal) by distillation with steam, the following are separated: NH 3 (in the form of concentrated ammonia water ), phenols, pyridine bases. After dilution with technical water, the purified water is directed to quenching coke or to biological treatment of wastewater to the treatment plant.
Coal tar (3-4% by weight of coal) is a complex mixture of organic substances (currently only ~ 60% of the resin components are identified — more than 500 substances). The resin by the method of rectification is subjected to separation into fractions: naphthalene, absorption, anthracene and coal tar. Of these, in turn, crystallization, filtration, pressing and chemical cleaning produce: naphthalene , anthracene , phenanthrene , phenols and coal oil.
Coke plants are one of the largest consumers of coal - up to of world production  .
Solid fuel coking
Method of processing solid combustible fuels by heating to 500–600 ° C without air access. The most common is the coking of combustible shale and brown coal. For the process using a continuous apparatus with external or internal heat supply. As a result of the process: semi-coke (50–70% of the mass of the initial fuel), primary resin (5–25%), primary gas , podmolnaya water are formed .
Coking heavy oil residues
Petroleum coke is obtained by coking liquid petroleum residues and pitches, by cracking and pyrolysis of petroleum distillation products, electrode pitch coke by coking high-melting coal tar pitch. Oil and electrode pitch coke is the main raw material for the production of electrodes . Petroleum and electrode pitch coke have a very low ash content, as a rule, not higher than 0.3% (up to 0.8% for petroleum coke) as compared with coal  .
Coking of heavy petroleum residues is a type of deep thermal cracking of hydrocarbons to produce petroleum coke and gas oil fractions. It is carried out at 420-560 ° C and pressures up to 0.65 MPa. The duration of the process varies from tens of minutes to tens of hours. The raw materials for the process are: heavy fractions of oil distillation, residues of deasphalting , thermal and catalytic cracking , pyrolysis of gasolines and gas oils.
The essence of the process consists in the successive reactions of cracking, dehydrogenation , cyclization , aromatization , polycondensation and compaction with the formation of a solid “coke cake”. The evolved volatile products are subjected to rectification to isolate the target fractions and their stabilization, the VAT residue is returned to the process. The finished coke is periodically discharged, dried and calcined .
According to the instrumentation, they are distinguished: delayed coking in unheated chambers (for producing low-ash coke), heated cubes (for producing electrode and special types of coke), coking in a “ fluidized bed ” powdered coke (so-called “thermal contact cracking”). When combining the latter method with gasification of coke, natural asphalt and bitumen may be involved in the process, in addition to oil residues.
- Dry distillation
- Coke battery
- Kozlovsky, 1985 , p. 49.
- Coke and coking // Encyclopedic dictionary of the young chemist. 2nd ed. / Comp. V. A. Kritzman, V. V. Stanzo. - M .: Pedagogy , 1990. - S. 117-118 . - ISBN 5-7155-0292-6 .
- Ch. ed. E. A. Kozlovsky. Mountain Encyclopedia in five volumes. Volume 2. - Moscow: Soviet Encyclopedia, 1985. - 575 p.