Coking Battery I. has been operating since 1956 and has 55 chambers, with a volume of 20 m³ each; in order to increase production, it became necessary in the 1980s to install a new battery. The construction of Coking Battery III. and service facilities was finished in November 1986, and the battery has 65 chambers, with a capacity of 41.6 m³ each. By 2000, the condition of battery III. deteriorated to such an extent that its overhaul could not be avoided. The overhaul was carried out in two phases. The overhaul of Coking Battery I. finished in 2003; that of Coking Battery II. ended in 2006. In order to extend the lifetime of Coking Battery I., the head ends of the heating wall were overhauled between 2006 and 2008. Taking the technical condition into consideration, the degasification time was increased to 20 - 24 hours.
Good quality coke can be produced from a mixture of coals with various coking characteristics. Coals for coking arrive at the Coal preparation plant from abroad (today, 2/3 of which comes from overseas) by rail. The carbon charge is prepared using the belt scales installed on the feed bunker line according to the parameters of the component carbons measured in the lab. The carbon charge is crushed to the appropriate grain size and homogenized, then transported via conveyors first to the coal towers of the Coking Batteries, and then to the chambers. If necessary, flue ash tar, pitch and coke powder can also be added to the coal charge, and organic sludge from the biological wastewater treatment plant is also included.
In the Furnace Plant, two PVR type (double heating duct, recirculating, regenerative heating) coking batteries are in operation. These are heated using coke oven gas. In the heating walls between the chambers there are heating ducts equipped with burners, and below the chambers there are regenerators that preheat the air. Depending on degasification time, the heating walls are continuously kept at a temperature of 1150 - 1350 °C. During the dry distillation (pyrolysis) of coal, it is kept separated from oxygen while heated to produce gases, liquid products and solid residues (coke). The high-temperature pyrolysis of coal is called carbonization. In the airtight chambers, the coal charge is heated for 16 - 24 hours; in the meantime, volatile materials are removed, and then the coke is pushed through the shield carriage into the extinguisher (battery I.) and into the container (battery III.). The coke produced in battery I. is cooled intensively by water spray, and then transferred via conveyor belts to coke screen I. The coke from battery III. is cooled below 150 °C by inert gas (CO₂ and N₂) circulated in countercurrent direction in the dry coke quenching chambers. The heated inert gas is used by heat recovery boilers to generate high pressure steam and - with the help of a turbine - electricity.
The coke screens separate the coke according to particle size and whether they were cooled by wet or dry quenching. The blast furnace coke fraction above 25 mm produced for ISD DUNAFERR Zrt. is transferred to the coke bunkers of the blast furnace directly via conveyors.
During the coking process, the crude gas exiting the burned coal at 700 - 750 °C and at a volume of 60 000 m³N/h is cooled down by water spray to 80 - 85 °C, sucked out of the gas collection system via separators, pre-coolers and electric tar separators by exhausters, and transferred for further gas cleaning to the Chemical Plant. The cruse tar separated from the gas is sold. The crude gas is transferred into washing towers. The washing liquid is distilled to remove ammonia and hydrogen sulfide. Ammonia is broken down into its constituents at 1100 - 1200 °C. The resulting flue gas produces steam. The hydrogen sulfide vapors are converted into high purity liquid elemental sulfur in Claus catalytic reactors. Crude benzene is then recovered from the coke oven gas in the washing and distillation towers of the benzene extraction plant, and loaded onto trucks to be delivered to customers.
45 % of the cleansed coke oven gas is led back into the system to heat the batteries. The remainder is delivered to ISD DUNAFERR Zrt. users. Storage and pressure equalization is ensured by a gas tank with a storage capacity of 150 000 m³.
Annual production volumes are: tar – 45 thousand tons, benzene – 10 thousand tons and sulfur – 1 thousand tons.
The commissioning of the Biological Wastewater Treatment Plant constructed in 1985 for the treatment of effluent water is of environmental significance. The plant is capable of treating 2000 m³ process waste water per day. Since the 2012 upgrade, nitrification/denitrification processes have been added to the process in order to meet stringent emission limits.
The total coking capacity of the Coking Plant is 0.9 million tons per year.
