Definition of coking terms

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Definition of coking terms: Gas explosion: The normal propagation of a flame occurs under certain conditions, at speeds ranging from a few centimeters per second to 10–15 centimeters per second. If ignition takes place inside a closed container, adiabatic compression causes the pressure and temperature of the combustible mixture within that container to rise sharply. At this point, the speed of flame propagation reaches several kilometers per second, and the intense reaction of the combustible mixture within the container results in tremendous destructive force, leading to an explosion. Heat transfer: The process by which heat moves automatically from an object with a higher temperature to an object with a lower temperature, due to the difference in their temperatures. Secondary decomposition: The products of coal thermal decomposition (referred to as primary pyrolysis products) inevitably undergo further chemical changes as they pass through the high-temperature coke, furnace body, and furnace roof area; this is known as secondary decomposition. Gas calorific value: refers to the amount of heat released upon the complete combustion of a unit volume of gas. Heat required per kg of wet coal: The amount of heat that must be supplied to convert 1 kg of wet coal into coke. Heat consumption per kg of dry coal: The heat required to produce coke from 1 kg of dry coal. Short circuit: The rising air stream, gas, and air do not pass through the vertical flue for combustion, but are instead introduced directly into the descending air stream chute through the circulation holes to burn there. Center temperature of the coke cake: During the coking process, it starts near the furnace samples in the carbonization chambers on both sides and gradually spreads toward the center surface of these chambers. The temperature of the feed material on the center surface of the carbonization chamber remains the lowest, and this can be used as an indicator of the degree of maturity of the coke cake. The temperature of the furnace sample on the center surface at the end of the coking process is referred to as the center temperature of the coke cake. Expansion pressure: The higher temperatures at the bottom and top of the carbonization chamber, as well as in the area near the furnace sample, cause a plastic layer to form around the coal material. This layer acts like a membrane bag; the pyrolysis of the coal within this bag generates gaseous products that cause the bag to expand, thereby exerting pressure on both sides of the carbonization chamber through the semi-coke layer and the coke layer. 26. High-temperature carbonization: The process in which bituminous coal is heated to 950–1050°C in an air-free environment, going through stages such as drying, pyrolysis, melting, bonding, and solidification/shrinking, to ultimately produce coke is called high-temperature carbonization. 27. Crush strength: When coke is subjected to impact forces, the cracks or defects appear on its surface; the ability of coke to resist such damage is known as its crush strength. 28. Wear resistance: When the frictional force acting on the surface of coke exceeds the strength of the pore walls in the coke, surface separation occurs, resulting in the formation of fragments and powder. The ability of coke to resist such damage is known as its wear resistance. 29. Coal blending for coking: This refers to the process of combining two or more types of coal in a uniform manner, at appropriate proportions, so that the advantages of each type of coal can complement one another. This approach enables the production of high-quality metallurgical coke while also allowing for more efficient use of coal resources and an increase in the production of chemical products. This process is known as coal blending for coking. 30. Coke ratio: refers to the weight of coke required to produce 1 ton of pig iron. 31. Screening: refers to the process of dividing mixed coke into several grades based on different particle size ranges. 32. Metallurgical coke: A general term for coke used in iron smelting, the melting of ferroalloys, and other metals. 33. Coke quenching: The coke oven operation process of cooling the red-hot coke to a temperature suitable for transportation and storage. 34. Coking time: The period from when coal is loaded into the carbonization chamber of the coke oven to when the coke cake is removed; it is generally defined as the time interval from when the coal pushing rod is inserted into the carbonization chamber until the tip of the coke pushing rod comes into contact with the coke cake. 35. Turnaround time: In coke oven operation, the time interval between two pushings of coke (leveling the coal) in the same carbonization chamber. 36. Coke oven machinery: The main specialized mechanical equipment used in coke oven operations during coke production. 37. Flammability limit: The range of proportions in which air mixed with gas or other flammable gases can explode is known as the flammability limit. 38. Explosion: When a combustible material mixes with air and catches fire in a confined space, it burns rapidly, releasing a large amount of heat in an instant, which causes a sharp increase in temperature and pressure. The speed at which the flame spreads can reach several hundred meters per second, or even several kilometers per second; this phenomenon is known as an explosion. 39. Protective grounding: It involves connecting the metal casing of electrical equipment to ground, thereby providing protection for operators’ safety in case the casing becomes charged due to a fault in the circuit equipment. 40. Safe voltage: If the current passing through the human body exceeds 0.05A, it can be life-threatening. Generally, when in contact with a voltage of 36V, the current flowing through the body does not exceed 0.05A; therefore, 36V is considered a safe voltage. In humid environments, the safe voltage must be set even lower, typically at 24V or 12V. 41. Element analysis: When the chemical composition of coke is determined based on elements such as C, H, O, N, S, and P, it is called element analysis. 42. Industrial analysis: The determination of the chemical composition of coke based on fixed moisture, ash, and volatile matter is referred to as industrial analysis of coke. 43. Coke sorting and inspection: refers to the process of first screening out coke lumps larger than 80 mm in size before grading mixed coke, breaking these lumps using a coke cutter, and then screening them together with the mixed coke. 44. Charring chamber taper: To facilitate coke pushing, the width of the charring chamber on the coke side is greater than that on the machine side, and the difference between these two widths is referred to as the taper. 45. Coke pushing sequence: The order in which coal is charged and coke is removed from each carbonization chamber of a coke oven is called the coke pushing sequence. 46. Pushing time: The time when the tip of the pushing rod comes into contact with the surface of the coke cake, marking the start of the coke pushing operation. 47. Coal loading time: The time when the coal leveling rod is inserted into the small furnace door to start the coal leveling operation. 48. Coal loading time: the interval from when the gate of the coal car is opened to when the coal leveling rod moves away from the small furnace door. 49. Total furnace operation time ； The sum of the operation times for each segment within a turnaround time. 50. Carbonization chamber treatment time: The interval from coke pushing time to coal charging time in the carbonization chamber. 51. Major cycle: The time interval for advancing carbonization chambers with the same sign at the same time on different dates. 52. Coal fineness: refers to the weight percentage of particles smaller than 3 mm in the coal material after it has been crushed; generally, the fineness of coal material is around 80%. 53. Coking property of coal: It refers to the ability of coal to form molten coke during coking. When crushed coal is heated in an air-free environment, pyrolysis of organic substances results in the formation of gums. Through the interaction among the gas, liquid, and solid phases of these gums, the degree of strength with which deformed particles stick together or with inert particles determines the coking property of coal. 54. Coking property of coal: Refers to the properties of the metallurgical coke formed during coal coking. Coal with certain binding capacity, after being pyrolyzed to a certain extent and gradually hardening to form semi-coke, continues to be heated; through thermal decomposition, heating, and polycondensation, more gases are released, the carbonaceous material becomes increasingly dense, and contraction cracks appear. The coking property of coal includes its cohesion before the formation of semi-coke and its shrinkage after the formation of semi-coke. 55. Combustion: The phenomenon in which a fuel undergoes rapid oxidation in air, producing light and heat. 56. Complete combustion: During combustion, the chemical reaction occurs completely, resulting in no combustible residues and the release of all heat. 57. Heat transfer: The process by which heat moves automatically from an object with a higher temperature to an object with a lower temperature, due to the difference in their temperatures. 58. Heat required per kilogram of wet coal: The amount of heat that must be supplied to convert 1 kg of wet coal into coke. 59. Heat consumption per kg of dry coal: The heat required to produce coke from 1 kg of dry coal. 60. Center temperature of the coke cake: During the coking process, it starts near the furnace samples in the carbonization chambers on both sides and gradually spreads toward the center surface of these chambers. The temperature of the feed material on the center surface of the carbonization chamber remains the lowest, and this can be used as an indicator of the degree of maturity of the coke cake. The temperature of the furnace sample on the center surface at the end of the coking process is referred to as the center temperature of the coke cake. 61. Expansion pressure: The higher temperatures at the bottom and top of the carbonization chamber, as well as in the area near the furnace sample, cause a plastic layer to form around the coal material. This layer acts like a membrane bag; the pyrolysis of the coal within this bag produces gaseous products that cause the bag to expand, thereby exerting pressure on both sides of the carbonization chamber through the semi-coke layer and the coke layer.