Although the coal laboratory staff's coal ash determination operation is simple, if they do not pay attention to the following problems, they may not obtain accurate measurement results.

      1. The high-temperature furnace should be well ventilated, and the chimney should be installed. Here it is emphasized that the chimney should be installed correctly. Generally, the inner diameter of the chimney is 25-30mm, depending on the size of the furnace. The chimney should be installed above the back of the furnace, the connection should be tight, and the height of the chimney should be appropriate, generally about 60cm. The furnace door has a ventilation hole with a diameter of 20mm.

      2. The position of the thermocouple should be correct. The thermocouple should not be close to the bottom of the furnace, but should be 20-30mm away from the bottom of the furnace. The thermocouple is equipped with a protective tube to prevent corrosion of the hot end. It is best to fill the end of the casing with alumina powder to reduce thermal hysteresis.

      3. The ash dish should be properly positioned in the furnace, and when quickly measuring the ash content of multiple samples, the coal with high sulfur content should be placed near the back of the furnace, and the coal with low sulfur content should be placed near the furnace door, so as to reduce the "cross-action" of the escaped sulfur oxides in the furnace and affect the measurement results.

      4. The ash dishes should be placed in a constant temperature area. When measuring the coal ash yield of multiple samples at the same time, it should be noted that each ash dish should be in a predetermined constant temperature area to maintain temperature consistency.

      5. The coal sample should be completely ashing. In addition to sufficient air in the furnace, the coal sample should also be weighed and the ash dish should be gently vibrated to spread out the coal sample, and its thickness should not exceed 0.15g/cm2 (0.15g per square centimeter).

      6. The air should be cooled down consistently. When taking out the ash dish with ash from the high temperature furnace, it is necessary to control the cooling time of the ash dish in the air. Generally, it is required not to exceed 5 minutes, and it is moved to the dryer for cooling. Because hot ash is a highly hygroscopic substance, it is easy to absorb moisture, and the time is too long, which increases the quality of ash.