Circulating fluidized bed boiler drying process - high strength refractory castable - zibo yuneng kiln

The oven process

Usually refractories have a certain moisture content.It is first from the surface began to evaporate, evaporation rate will be reduced with the moisture content of refractories.In the initial stage, low temperature and large amount of dry smoke should be adopted.The drying rate should be controlled (the maximum drying rate that will be reached at this time). As the temperature rises, the drying rate decreases.In the latter stage, a higher temperature can be maintained in the dry area to maintain a good oven process.

The oven is divided into two stages:

The first stage: oven machine oven;

The second stage: this stage is when the whole boiler is started, the normal operation of the boiler with the main oil gun for further drying of refractory materials.At this stage, in order to protect the boiler reheater, the turbine should be put into operation.

The first stage of temperature measurement control

According to the temperature returned by the thermocouple and the predetermined oven curve, by adjusting the oil content and air distribution of the oven, the temperature of each place meets the requirements of the predetermined oven curve.

The temperature is measured not directly on the surface of refractory, but on the temperature of flue gas.Because the temperature rise of refractory material will lag behind the temperature of flue gas, it is safe to control the temperature of flue gas.Take the average of the corresponding side points for the temperature of each region.

The first stage of the oven process matters needing attention

(1) all temperature measuring points will be recorded and archived during the whole oven process.

(2) in the process of oven, all water wall pipes and heating surface pipes of slag cooler must maintain water circulation.

(3) in the process of oven, cooling water and cooling air must be passed through the ash control valve of the cooler slag.

(4) in the process of oven, sufficient discharge space should be left around the exhaust steam hole on the outlet flue of separator.

The first stage oven bill is signed

Use the same material and thickness of each part, prefabricate test block, put in the corresponding part before the oven should be internal, take out and analyze after the end of the oven insulation, if the moisture content is less than 2.5%, it can be cooled according to the oven curve.After the temperature drops to normal temperature, samples of corresponding parts are taken for analysis according to relevant standards, and the analysis results shall prevail.

Production of test blocks:

(1) furnace bottom: steel fiber wear-resistant refractory castable, specification: 250*250*180(thick), four sides and bottom are sealed with steel plate, quantity: 2.

(2) four sides of lower furnace and hanging screen: wear-resistant refractory plastic, specification: 250*250*34 (thick), four sides and bottom are sealed with steel plate.

(3) feed legs, inlet and outlet flue of separator, slag cooler: wear-resistant refractory castable and temperature maintaining castable, specification 250*250*350(wear-resistant refractory castable thickness l 50, insulation castable thickness 200), four sides and bottom (insulation castable) are sealed by steel plate.

Or the limit sampling method is adopted, namely, 100g insulation castable is taken at the part with the most water content and the opening at the top of the flue, and 50g is respectively loaded into two sealed vessels, and one vessel is gradually heated to 145℃ in the laboratory oven, and measured for 1 hour after insulation. If the moisture content is less than 2.5%, then the oven is qualified.The temperature can be lowered by oven curve.The other vessel was put into the laboratory oven and gradually heated to 110℃. It was weighed for 24 hours after insulation, such as the moisture content was less than 2.5%, that is to check the oven qualified.

First stage oven curve

The heating curve of the oven in the second stage

Language description time of temperature rise curve in the second stage (hours)

Ambient temperature

1) heating to 130℃ for 4 hours at a rate of 25-30℃/h

2) heating to 300℃ for 3-4 hours at the rate of 50℃/h

3) keep it at 300℃ for 6 hours

4) heating to 500℃ for 6 hours at a rate of 50℃/h

5) holding time at 500℃ for 2 hours and 2 hours

6) heated to 670℃ for 3 ~ 4 hours at a rate of 50℃/h

7) keep it at 670℃ for 4 hours

8) heat to the normal operating temperature for 3 hours

The drying process takes about 32 hours