Drying requirements for furnace lining

The drying curves for refractory materials vary depending on the different types of equipment, the various kinds of refractory materials, and the way in which these materials are combined; for example, there are significant differences in the drying curves between bricks and castables, as well as between plasticizable refractories.

This question is difficult to answer as it is too broad. The lining material is chosen based on varying working temperatures, different types of working media, and various other operational conditions – materials such as refractory bricks or unfired refractory products may be used. It is also necessary to determine the structural design and lining thickness that suit the working environment. Different lining thicknesses, structural designs, and material types require distinct drying procedures (heating curves). Therefore, it would be helpful if the question could be specified more precisely, so that we can discuss it better and improve together.

Drying and heat treatment schedule for casting materials: Temperature range in °C, Rate of temperature rise/fall in °C/h, Required time in hours. Normal temperature to 110: 5–10, 9–18; 110±5: 0, 24. 110 to 315: 10–15, 14–21; 315±5: 0, 24. 315 to 540: 20–25, 9–12; 540±5: 0, 24. 540 to normal temperature: ≤25, ≥21. Last edited by mingjiazhao on 2008-1-18 16:28

The main methods for drying furnace linings are as follows: 1. Removing moisture from the lining by heating the furnace with steam through the water-cooled walls in the lining. 2. Heating the furnace using flames; this can be achieved by burning wood, coal powder, natural gas, oils, etc. In whatever method is used, it is necessary to control the intensity and temperature of the flame in order to ensure proper drying of the lining. 3. The drying process must be carried out in accordance with the design specifications – there are specific requirements regarding the time required for heating, the time needed to maintain a constant temperature, the rate of cooling, and the desired temperature levels. The exact details depend on the actual characteristics of your company’s lining.

I’ve checked relevant information; it’s related to both ventilation and the thickness of the lining material. I’m currently gathering more information on this

Well, that’s a good suggestion. I collect too

For air-hardening linings, it is not necessary to carry out baking; chemical agents such as aluminum phosphate can be used as binders, and sufficient curing time at room temperature makes baking unnecessary. For water-hardening linings, since cement is used as the binder, the lining contains a large amount of moisture, which must be removed through heat. The typical temperatures required are: 150°C to remove free water, 320°C to remove crystalline water from the surface layer of the lining, and 500°C to remove crystalline water from within the lining along its thickness. To avoid damage to the lining, it is better to use a low heating rate and a long period of constant temperature, but this needs to be balanced with the manufacturing or commissioning schedule. It should be noted that it is impossible to remove all the moisture from the lining using a baking curve; removal only occurs within a certain thickness of the lining’s surface layer. It generally takes more than one month to remove most of the moisture

The design operating temperature for the conversion reactor of the Klaus process S is 300 degrees; according to the requirements of the design institute, the lining should be heated to 500 degrees. Is this necessary?

The temperature in the S-producing furnace exceeds 1000 degrees; the process gas emerging from this furnace undergoes a second-stage low-temperature Claus conversion to further increase the sulfur recovery rate. There are no flames in these two-stage conversion reactors, and the reaction temperature is generally around 270 degrees.

Which type of furnace is the poster referring to, and what kind of lining is used? For processes such as Claus converters, gasifiers, boilers, and gas generation furnaces, the temperature requirements for the linings vary

The furnace drying curve is usually provided by the material manufacturer, but it is also necessary to draw such a curve during the drying process. During this process, both the rate of temperature increase and decrease are strictly controlled; that is, when cooling down, forced cooling is not allowed, and there must be a time interval for this process

1. When using steam for oven drying, the air vents and flue doors should be opened to enhance natural ventilation； Steam supply must not be interrupted during furnace drying. 2. The flame baking method: The burning flame should be at the center of the furnace, with even combustion; the temperature should rise slowly, without sudden changes in temperature, and it is not allowed to use intense flames at one time and then reduce the heat intensity at another. 3. 2 to 3 days after starting the furnace heating, the continuous blowdown valve can be opened intermittently to remove floating contaminants. During the middle and later stages of furnace drying, the regular sewage discharge valve should be opened every 4 hours to discharge waste water. When draining wastewater, the water level in the furnace should be raised to a high level; once the level drops back to the normal level after drainage, the drain valve should be closed. 4. After the furnace reaches a certain temperature, steam generation can cause the water level to drop, so water should be added promptly to prevent an incorrect water level reading from occurring. During the furnace drying process, the emergency drain valve can be used to maintain the water level in the boiler drum, preventing very dirty furnace water from entering the superheater. 5. When drying the coal furnace, try to minimize the opening of inspection doors, viewing ports, manholes, etc., to prevent cold air from entering the furnace and causing cracks in the furnace walls. 6. During the furnace drying process, it is necessary to regularly inspect the furnace walls and the drying progress, control the temperature in accordance with the requirements of the drying curve, and monitor the temperature rise of the furnace walls. Regular observation, inspection, and recording are essential to prevent cracks and bulging deformations in the furnace walls. 7. In the later stage of furnace drying, when the moisture content in the refractory brick mortar reaches 7%, and that in the red brick mortar reaches 7%~10%, the furnace can be boiled simultaneously.