What does \"reversed coal quality\" mean?
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According to the results from the coking plant’s laboratory, the sulfur content in the coal is even higher than that of the coal fed into the furnace, and this situation persists almost every day. One chief engineer said, “It’s not a problem with the laboratory. Do you know what ‘reversed coal quality’ is?” ” May I ask what exactly causes the lack of quality inversion? What caused it?
It means that the sulfur content in the coke is higher than that in the coal fed into the furnace.
Sulfur in coal is divided into organic sulfur and inorganic sulfur based on its form of existence. Some coals also contain a small amount of elemental sulfur. Sulfur in coal is divided into combustible sulfur and non-combustible sulfur, depending on its ability to burn in air. Organic sulfur, pyrite sulfur, and elemental sulfur can all burn in air; they are all combustible forms of sulfur. Sulfate sulfur cannot burn in air; it is non-flammable sulfur. The sulfur remaining in coke after coal coking (primarily in the form of organic sulfur, calcium sulfide, and ferrous sulfide) is known as solid sulfur. Sulfur that is released along with gas and tar during coal coking is known as volatile sulfur (primarily in the form of hydrogen sulfide and carbon monoxide sulfide (COS)). The fixed sulfur and volatile sulfur in coal are not constant; they vary depending on factors such as coking temperature, heating rate, and the nature and quantity of mineral components. The total amount of sulfur in various forms in coal is referred to as the total sulfur content of coal (St).
During the coking process, part of the sulfur in coal goes into the gas, while another part ends up in the coke. Assuming that 60–70% of the sulfur ends up in the coke, 1 ton of coal can produce k tons of coke (where k is the coking rate, taken as 0.75). Thus, 1 × S_coal × (60–70)% = k × S_coke. Therefore, S_coal : S_coke = 0.75 : (60–70)%; hence, S_coal : S_coke > 1. In other words, under normal circumstances, the sulfur content in coal is higher than that in coke.