The issue of coal’s ash fusion point
Thread Content
The ash fusion point of coal is closely related to the operating temperature of the gasification furnace. Whether it is a fluidized bed or a pneumatic bed, whether it is water-coal slurry or pulverized coal. Regarding water-coal slurry, some people say that the ash melting point should not exceed 1300 degrees, and since the slag is discharged in a liquid state, the operating temperature must be above 1300 degrees. I have a question here: 1. Does the gasification furnace have a mechanism to measure this temperature? Is it the surface temperature or the core temperature of the vaporization furnace that is being measured? 2. Does the ash fusion point refer to T1, T2, or T3? I hope the guys here can give some explanations. Thank you! Q
1. Refers to the temperature inside the gasification furnace; the Texaco furnace is equipped with thermocouples for measurement, but they often break. Shell is a calculated value, and high accuracy and reliability are required for the associated gauges. 2. It should refer to FT, i.e., flow temperature. Refers to the temperature of the molten slag at a viscosity of 15–25(40) Pa·S
1. The temperature inside the furnace also depends on the insertion depth; in our plant’s fluidized bed, the length of the refractory material that is exposed is less than 5 cm. Therefore, the temperature inside the furnace varies as well; there are nozzle jets at the Texaco center, so the temperature there is likely higher than that near the wall surface? ? ? Furthermore, perhaps the temperature distribution throughout the entire furnace of the fluidized bed is relatively uniform? ? ? ?
The term \"center temperature\" refers to the reaction temperature. To better understand the ash melting point of coal during reactions, the concept of T4 has been introduced; at this temperature, coal exhibits the best viscosity-temperature characteristics.
Find some information: the ash fusion temperature and the viscosity of molten ash. The coal ash is shaped into a triangular pyramid and placed in a high-temperature furnace, where it is heated under a specific atmosphere. The changes in the shape of the ash pyramid are observed in order to determine the deformation temperature T1, the softening temperature T2, and the flow temperature T3; here, T2 represents the melting point of the coal ash. The viscosity of molten ash is measured using a high-temperature viscometer. The T2 softening temperature is generally considered to be the ash fusion point. In fact, different processes have their own industry-specific terms, which it is necessary to understand; for example, by \"fluidized bed\" we usually mean T2.
What kind of thermocouple can be inserted into the center, withstand high temperatures, and have sufficient strength? The airflow in the center exerts quite strong forces on the particles present there.
Could you please provide a detailed explanation of what T4 is? Thank you
Which temperature point in the gasifier is the most representative? The temperature in the oxidation reaction zone is definitely the highest ； The temperature corresponding to the ash fusion point should first be at the slag outlet; only when the temperature there is higher than the ash fusion point can liquid slag discharge be ensured.
The ash melting point refers to T4, that is, the flow temperature of the ash.
T4 generally refers to the temperature of the slag when it is in a flowing state, specifically the temperature at which the viscosity of the liquid slag is 25 MPas! Now, the high-temperature thermocouples from Chongqing Instrument Research Institute, after being modified, generally have a longer service life as well! The gasification furnace temperature mentioned by Tianya is also used by Texaco! However, without thermocouples, a skilled operator can generally determine this from various indicators; the same was done in previous gasification operations
In fact, the thermocouple can be buried behind refractory bricks; there is no need to expose its tip to the gasification atmosphere. This approach can also extend the service life of high-temperature thermocouples, or slag can be used to achieve self-protection against slag