1. Development History of Coke Oven
A coke oven, also known as a coking oven, is the core equipment for coal coking and a key facility in coking technology. Coal coking technology has a history of more than 200 years, and the structural form of coke ovens has been continuously upgraded with the development of the industry. In the early stage, the coking process imitated charcoal burning and adopted heap carbonization to produce coke. In the mid-18th century, coking equipment was gradually improved into brick-built semi-enclosed long kilns. In 1763, fully enclosed circular kilns (honeycomb ovens) were officially put into operation.
The early heap carbonization and kiln carbonization both adopted an internal heating mode, in which carbonization and combustion were integrated. Part of the raw coal and carbonization gas were burned to heat the remaining coal for coking. In the mid-19th century, coke oven technology underwent a transformative upgrade to external-heating carbonization chamber coking, with the emergence of the reverse-flue oven. This equipment separates the carbonization chamber from the combustion chamber via a partition wall with upper passages. The carbonization gas generated in the carbonization chamber flows into the combustion chamber through the passages, mixes with air supplied from the top flue, and burns downward, forming the basic characteristics of modern coke ovens.
In the 1870s, coke ovens capable of recovering chemical products were successfully developed, transforming the coking industry from single coke production to comprehensive multi-product production. In 1883, regenerative coke ovens were put into use to fully recover waste heat from flue gas. Since then, the overall structure and process of modern coke ovens have been basically finalized.
2. Structural Composition and Process Parameters of Modern Coke Oven
The main body of a modern coke oven consists of three core parts: carbonization chambers, combustion chambers and regenerators. The whole oven is built with silica bricks featuring excellent high-temperature resistance, and the maximum flue temperature can reach 1400℃. The conventional dimensions of a carbonization chamber are 0.4～0.5 m in width, 10～17 m in length and 4～7.5 m in height. Coal charging holes and gas ascension pipes (arranged on the machine side or coke side) are set on the top, and both ends are sealed by oven doors, forming the core area for coal carbonization and coking. Combustion chambers are symmetrically arranged on both sides of carbonization chambers and composed of multiple vertical heating flues to provide stable heat for coking. Regenerators are located at the lower part of the oven body, divided into air regenerators and lean gas regenerators, which are mainly used to recover and utilize flue waste heat to improve energy efficiency.
The coke oven adopted in this project is a single-heat type oven with superior structural advantages, including twin flue design, waste gas circulation, wide carbonization chambers, wide regenerators and bottom injection of coke oven gas, ensuring high process adaptability and production stability. The coking cycle ranges from 13 to 18 hours, depending on the carbonization chamber width and flue temperature. With the upgrading of industrial technology, modern coke ovens are developing toward large-scale design, and the effective volume of a single carbonization chamber has reached 50 m³. Measures such as optimizing oven wall structures are adopted continuously to improve the overall production capacity of coke ovens.
3. Production Process and Supporting Facilities of Modern Coke Oven
Modern coke ovens are equipped with a complete set of special mechanical equipment, mainly including coal charging cars, coke pushers, coke guide cars and coke quenching cars, realizing full-process mechanized coking operation. In production, proportioned raw coal is charged into the carbonization chamber by a coal charging car. After high-temperature carbonization, the formed coke is pushed out of the oven by a coke pusher. The red-hot high-temperature coke falls into the coke quenching car through the guidance of the coke guide car, and is cooled by wet coke quenching, while dry coke quenching with waste heat recovery is also available. The quenched coke is transported to the coke bench, screened and graded before being delivered as finished products.
To optimize production conditions and realize green production, modern coke ovens adopt full mechanization and automatic control systems, equipped with flue dust control and sewage treatment facilities, and apply computer technology for intelligent and precise operation. Ground dust removal stations are specially installed for coal charging and coke pushing processes to effectively control production dust and ensure clean production.
4. Production Process of Coal Preparation Workshop
As a pre-core process of coking production, coal preparation covers four major links: coal stockpiling, coal blending, crushing and conveying, which provides qualified raw materials for the continuous and stable operation of coke ovens.
Coking coal raw materials are divided into purchased external clean coal and local clean coal. External purchased clean coal is transported to the plant by railway, unloaded through discharge chutes, and conveyed to the clean coal stockyard by belt conveyors. Local clean coal is directly delivered to the stockyard by trucks from mining area coal washing plants. The coal stockyard is mainly used for classified storage of various coking coals.
After a certain period of stockpiling, coking coal achieves uniform quality and natural dewatering, avoiding the adverse impact of coal quality fluctuation on coking production. It not only ensures continuous, balanced and stable operation of coke ovens, but also stabilizes the quality of finished coke. The designed capacity of the proposed coal yard is 35,000 tons, and the operating capacity is 27,000 tons. Calculated based on the use of four types of coking coal, it can meet the 15-day coal consumption demand of the coke oven.