Problems with the initial drying process of 75t/h fluidized bed boilers

Here is a method for the red route that you can refer to: Section 6.1 General Provisions, 6.1.1 For newly installed or newly overhauled furnaces, it is necessary to carry out drying operations in order to prevent the furnace walls from losing moisture too rapidly, which could lead to cracks or even damage, and also to ensure the integrity and safety of the equipment. 6.1.2 The furnace drying process must be carried out in strict accordance with the provisions of these regulations; the drying time and temperature must be carefully controlled, and temperature changes in various parts must be thoroughly monitored during the drying period. 6.1.3 To remove rust and other dirt formed during the manufacturing, handling, storage, installation, and maintenance of the boiler, it is necessary to conduct a boiler boiling process depending on the degree of dirt and rust on the boiler. 6.1.4 The boiler’s boiling process can be carried out separately or at the later stage of drying; the boiling process remains a continuation of the drying process. 6.1.5 Oven drying should be carried out after the wall construction is completed and after it has dried naturally for a period of time. 6.2 Conditions and preparatory work required for furnace drying 6.2.1 The boiler and its auxiliary equipment must be fully assembled, overhauled, and tested successfully; the air leakage test of the furnace walls must also pass. 6.2.2 The boiler itself and its associated water system must pass hydrostatic tests. 6.2.3 The water system, as well as the oil and gas systems, must be ready for operation at any time. 6.2.4 Prepare all temperature measurement points and sampling points in the furnace properly, and verify their accuracy. 6.2.5 Prepare all necessary items before heating the furnace. 6.2.6 All instruments are in good condition and records are complete. 6.2.7 Operators must be well familiar with the furnace drying plan to have a clear understanding of it. 6.2.8 Have the conditions for starting the furnace ready, and complete all preparations prior to starting it. 6.2.9 The softened water used before furnace drying must pass testing before it is allowed to be used for starting the furnace drying process. 6.2.10 Before heating the furnace, empty the superheater; open the vent valve of the steam drum and close the blowdown valve. 6.3 Technical requirements and specifications for furnace drying 6.3.1 This boiler can be dried using wood or gas, as well as steam or fuel oil. If a boiler is in operation, the drying process can be adjusted using steam. At the beginning, regardless of the fuel used, it is not allowed to use intense heat for heating, in order to prevent the furnace walls from losing water too quickly and developing cracks. 6.3.2 Before starting the boiler, fill it with water slowly until the water level reaches 1/3 of its capacity. 6.3.3 Ignite in accordance with the boiler ignition procedure. 6.3.4 During furnace drying, the bubble level should always be maintained at half of the normal range. 6.3.5 The temperature rise rate and duration of furnace drying shall follow the furnace drying curve. 6.3.6 The combustion intensity and temperature rise are controlled by the flue gas temperature after the superheater; during the heating up of a light-type furnace wall, the temperature rise on the first day should not exceed 80°C, and the temperature increase should not exceed 25°C per day thereafter. The flue gas temperature in the later stages should not be higher than 160°C, and this highest temperature level should be maintained for at least one day and one night. 6.3.7 If the furnace wall is particularly moist, the rate of temperature increase should be appropriately reduced. 6.3.8 The opening and closing positions of the valves used for furnace drying are as follows: ① The air valves at the superheater outlet header and the steam drum are opened. ② The drain valve at the superheater header is opened. ③ The main steam valve at the steam outlet and all sampling valves are closed. ④ All blowdown valves are tightly closed. 6.3.9 The time and temperature required for furnace drying are shown in Table 2.1. Table 2.1: Furnace Drying Time and Temperature. Furnace wall type: Light furnace wall, Heavy furnace wall. Furnace drying time (days): 0.5–6, 10–14; this step can be skipped. Temperature before and after heating with coal: On the first day of drying, the temperature is <80°C

Here is a method for furnace drying that you can refer to: Section 6.1 General Provisions, 6.1.1 For newly installed or recently overhauled furnaces, it is necessary to carry out furnace drying in order to prevent the furnace walls from losing moisture too rapidly, which could lead to cracks or even damage, and also to ensure the integrity and safety of the equipment. 6.1.2 The furnace drying process must be carried out in strict accordance with the provisions of these regulations; the drying time and temperature must be carefully controlled, and temperature changes in various parts must be thoroughly monitored during the drying period. 6.1.3 To remove rust and other dirt formed during the manufacturing, handling, storage, installation, and maintenance of the boiler, it is necessary to conduct a boiler boiling process depending on the degree of dirt and rust on the boiler. 6.1.4 The boiler’s boiling process can be carried out separately or at the later stage of drying; the boiling process remains a continuation of the drying process. 6.1.5 Oven drying should be carried out after the wall construction is completed and after it has dried naturally for a period of time. 6.2 Conditions and preparatory work required for furnace drying 6.2.1 The boiler and its auxiliary equipment must be fully assembled, overhauled, and tested successfully; the air leakage test of the furnace walls must also pass. 6.2.2 The boiler itself and its associated water system must pass hydrostatic tests. 6.2.3 The water system, as well as the oil and gas systems, must be ready for operation at any time. 6.2.4 Prepare all temperature measurement points and sampling points in the furnace properly, and verify their accuracy. 6.2.5 Prepare all necessary items before heating the furnace. 6.2.6 All instruments are in good condition and records are complete. 6.2.7 Operators must be well familiar with the furnace drying plan to have a clear understanding of it. 6.2.8 Have the conditions for starting the furnace ready, and complete all preparations prior to starting it. 6.2.9 The softened water used before furnace drying must pass testing before it is allowed to be used for starting the furnace drying process. 6.2.10 Before heating the furnace, empty the superheater; open the vent valve of the steam drum and close the blowdown valve. 6.3 Technical requirements and specifications for furnace drying 6.3.1 This boiler can be dried using wood or gas, as well as steam or fuel oil. If a boiler is in operation, the drying process can be adjusted using steam. At the beginning, regardless of the fuel used, it is not allowed to use intense heat for heating, in order to prevent the furnace walls from losing water too quickly and developing cracks. 6.3.2 Before starting the boiler, fill it with water slowly until the water level reaches 1/3 of its capacity. 6.3.3 Ignite in accordance with the boiler ignition procedure. 6.3.4 During furnace drying, the bubble level should always be maintained at half of the normal range. 6.3.5 The temperature rise rate and duration of furnace drying shall follow the furnace drying curve. 6.3.6 The combustion intensity and temperature rise are controlled by the flue gas temperature after the superheater; during the heating up of a light-type furnace wall, the temperature rise on the first day should not exceed 80°C, and the temperature increase should not exceed 25°C per day thereafter. The flue gas temperature in the later stages should not be higher than 160°C, and this highest temperature level should be maintained for at least one day and one night. 6.3.7 If the furnace wall is particularly moist, the rate of temperature increase should be appropriately reduced. 6.3.8 The opening and closing positions of the valves used for furnace drying are as follows: ① The air valves at the superheater outlet header and the steam drum are opened. ② The drain valve at the superheater header is opened. ③ The main steam valve at the steam outlet and all sampling valves are closed. ④ All blowdown valves are tightly closed. 6.3.9 The time and temperature required for furnace drying are shown in Table 2.1. Table 2.1: Furnace Drying Time and Temperature. Furnace wall type: Light furnace wall, Heavy furnace wall. Furnace drying time (days): 0.5–6, 10–14; this step can be skipped. Temperature before and after heating with coal: On the first day of drying, the temperature is <80°C

I have some concerns regarding the heating time and temperature for preheating the furnace mentioned above; the heating curve for the furnace should be determined according to the information provided by the manufacturer of the refractory coating, rather than being fixed in advance

Using a professional oven drying machine for drying is an option; one can also hire a specialized oven drying company to do the job, which helps save time, fuel, and money. For heating with fuel or gas, just choose one type of fuel – there is no need to switch midway. Heating can be done at low, medium, or high temperatures: low-temperature heating ranges from 20 to 200°C, medium-temperature heating from 200 to 350°C, and high-temperature heating from 350 to 850°C (this is carried out when the boiler is started up). The maximum temperature achievable with a heating device is 350°C. Generally, the heating time is between 5 and 7 days, depending on the heating curve provided by the manufacturer of the refractory material. The fuel consumption is also related to this heating curve; generally, a 75 t/h boiler requires around 30 tons of fuel for heating. This post was last edited by *anpangpang on 2009-3-5 at 17:02

Our plant uses wood to heat the circulating fluidized bed boilers; wood is added through the furnace door, and it burns for about 8 days – the requirements aren’t very strict.

Generally speaking, a 75t/h boiler requires about 30 tons of fuel for drying. Are you referring to the fuel consumption per hour?