I. Method for Determining the Thermal Stability of Coal
First, take coal samples with a particle size of 6-13mm, heat them in an air-free muffle furnace at (850±15)℃ for 30 minutes, weigh them, and sieve them. The percentage of residual coke mass with a particle size greater than 6mm to the total residual coke mass of all grades is used as the thermal stability index TS+6. The fraction of the residual coke mass of 3-6mm and less than 3mm respectively accounting for the total residual coke mass of each grade is used as the auxiliary thermal stability indicators TS3-6 and TS-3.
Ii. Instruments and equipment required for the thermal stability of coal
JN-800A high-efficiency energy-saving intelligent ash volatilization tester: The constant temperature zone is no less than 100mm×230mm, equipped with a constant temperature regulation device and can be maintained at (850±15)℃. It is equipped with a thermocouple and a pyrometer. There are volatile matter discharge holes and thermocouple insertion holes left on the rear wall of the furnace.
2. Reciprocating vibrating screen: Reciprocating compound, amplitude (40±2)mm, frequency (240±20)min-1.
3. Round hole screen: A square screen that matches the holes of the vibrating screen. The hole diameters are 6mm and 3mm, and they are equipped with a sieve cover and a sieve base.
4. Industrial balance: Maximum weighing capacity 1kg, sensitivity 0.01g.
5. Equipped with a 100ml porcelain crucible or corundum crucible.
6. Crucible rack: Made of metal materials with a temperature resistance of over 900℃. The crucible rack can be made to hold 5 or 10 crucibles.
Iii. Steps for Determining the Thermal Stability of Coal
About 1.5kg of air-dried coal sample with a particle size of 6-13mm is required. Carefully screen out the pulverized coal smaller than 6mm, then mix it evenly and divide it into two parts.
2. Use a crucible (2)5 to take 500 cubic centimeters of coal samples from each of the two coal samples, weigh them accurately to 0.01g, and ensure that the masses of the two samples are the same (±1g). Put each coal sample into five crucibles respectively, cover the crucible LIDS and place the crucibles on the crucible rack (2)6.
3. Quickly place the rack containing the crucible into the constant temperature zone of the muffle furnace (2)1, which has been heated to 900℃. Manage the furnace door well and adjust the furnace temperature to (850±15)℃; otherwise, the measurement will be invalid.
4. Remove the crucible from the ash content measuring instrument (muffle furnace), cool it to room temperature, and weigh the total mass of each residual coke (accurate to 0.01g).
5. Stack the sieves with aperture sizes of 6mm and 3mm and the sieve base (2)3 on the vibrating screen machine (2)2. Then, pour the weighed one-cent residual coke into the 6mm sieve, preferably with a sieve cover and fix it.
6. Start the vibrating screen and screen for 10 minutes.
7. Weigh the mass of each grade of residual coke with a particle size greater than 6mm, 3-6mm and less than 3mm after screening respectively (accurate to 0.01g).
8. The difference between the sum of the masses of each grade of residual coke and the total mass of residual coke before screening should not exceed ±1g. Otherwise, the formulation will be invalidated.
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