Comrades, how is the wall temperature of the Shell gasifier measured?

1. The temperature of the shell water wall cannot be measured. Due to the protection provided by slag accumulation, the temperature on the inner surface of the water wall is normally below the ash melting point. Both the outer surface of the water wall and the interior surface of it are at the temperature of saturated water. I don’t think it’s necessary to measure the temperature of the pressure-bearing components 2. Due to the harsh operating conditions inside the gasification furnace, there are currently no reliable thermometers available for measuring the temperature.

The measurement of the furnace wall temperature is primarily used to monitor the operation of the furnace. For Texaco gasifiers, it is possible to detect the degree of thinning of the refractory bricks, which is crucial for safe operation. The measurement of the temperature in the annular space of the Shell gasifier also reflects the operating condition of the water-cooled wall tubes. It can be said to be important. “The water-coal slurry gasifier is a pressure vessel, with a normal temperature inside of around 1300°C, or even as high as 1500°C. The refractory bricks lining the interior of the furnace melt at such high temperatures; coupled with the erosion caused by hot gases and slag, the refractory bricks thin out or even fall off, and hot gases entering through the gaps between the bricks can raise the surface temperature of the gasifier’s walls. The strength of the metal shell of the gasification furnace under pressure decreases, and its allowable stress drops rapidly, posing a threat to the safe operation of the equipment; therefore, it is necessary to monitor the surface temperature of the gasification furnace and issue alarms when necessary. Another reason is that the surface temperature of the furnace reflects the degree of thinning of the refractory bricks inside it, allowing for the predetermined timing of their replacement. Due to the different pressures used in the gasification furnaces, as well as the varying metal materials used for the pressure vessel shells, the requirements regarding the surface temperature of these shells differ. Vaporization furnaces with a value of 4.0 MPag or less, whose surface temperature ranges from 200 to 280°C, with around 230°C under normal conditions. The vaporization furnace has a capacity of 6.5 MPa, with a surface temperature ranging from 400 to 450°C, typically around 425°C. ”

Is it possible to do it indirectly? For example, through flue gas analysis and so on.

At 4.0 MPa, the temperature of Texaco is 200–240 degrees; at 6.5 MPa, the wall temperature is 230–260 degrees – it is not possible to reach 425 degrees. This is also related to the amount of coal fed into the gasification furnace, as the heat load varies. 400-450 is the design temperature for SA387 material.

Hello, Koolar friend. The temperature you mentioned is a bit low; it’s true that it should not exceed 425 degrees. However, the actual wall temperature is 260–275 degrees at 6.5 MPa, and 240–255 degrees at 4.0 MPa.

Shell calculates the reaction temperature inside the furnace as well as the wall temperature of the furnace based on the temperature of the fluid flowing within the water-cooled tubes. I am currently working on more precise calculation methods, but a simpler approach involves using the heat transfer calculations for those tubes; this can be done by referring to the methods used for calculating boiler wall temperatures. I recommend the book “Boilers” published by Xi’an Jiaotong University Press, which explains that such calculations are carried out through iterative processes. I’ve done a rough calculation: if the heat load isn’t particularly high, the external wall temperature won’t be much higher than the temperature of the medium; 50 degrees is already quite high. Calculating the reaction temperature inside the furnace is much more complicated, as there are too many factors involved

If heat transfer deteriorates, the situation will be different

I’m a beginner; I didn’t realize there was so much to knowing how to measure the wall temperature of a furnace. Thank you

The furnace temperature of SHELL cannot be measured directly; the calculation formula takes many factors into account.

No one mentioned that it was measured using thermocouples (from the automation field); infrared thermometers can also be used (from the process engineering field). Use a 40-meter-long CTTT thermocouple wrapped around the surface of the vaporization furnace, and manage it in sections to enable over-temperature alarms. As for thermocouples, they are of course made from special materials; they only display the temperature value at the highest temperature point, providing selective output to achieve the purpose of temperature measurement.

It is not measured directly, as temperature is not a direct parameter of control. It is necessary to know the FT of coal in advance; by controlling the oxygen-to-coal ratio and amount, the gasification reaction in the reaction chamber can be regulated so that, after a complete layer of slag forms on the water-cooled walls, the liquid slag can still flow well. The temperature can be calculated from the heat of the water wall. The discharge of slag can indicate whether the reaction is proceeding normally and whether the temperature in the gasification chamber is too high or too low; this is controlled by the system through interlock reactions. GE’s furnaces need temperature control due to the refractory bricks. The water wall is a membrane wall, and it’s impossible to reach the temperature measurement points inside the reaction chamber in order to take temperature readings!