Design and application of the hottest high tempera

2022-09-19
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Design and application of high temperature axial fan introduction at present, 78% of cement in China is produced by shaft kilns. The flue gas from shaft kilns has the characteristics of large emission, high dust content, high temperature, high moisture content and large fluctuation of gas conditions. The flue gas volume of shaft kiln is 30000 ~ 60000m/h; The dust content of flue gas is 1 ~ 10g/m (usually 5g/m); The flue gas temperature is 50 ~ 200 c, which is higher when the kiln condition is abnormal; The moisture content of flue gas is 5% - 10%, and it is as high as 20% during primer drawing; Due to the high moisture content of the flue gas, the dew point of the shaft kiln flue gas reaches 40 ~ 55 C, even as high as 77. The flue gas dust is relatively coarse. 50% of the flue gas is larger than 40 m in the case of shallow and dark fire operation, and 45% of the flue gas is larger than 40 m in the case of dark fire operation; The flue gas condition changes frequently with the operation of the shaft kiln and raw materials. This kind of experimental machine adopts a large flow servo valve system, which is fast and wide

water dust collector is widely used in shaft kiln dust collector. It has the characteristics of simple process, small investment and low operation cost, but water dust collector has the problem of smoke pouring out. The spray water of the water dust remover increases the resistance of flue gas emission and makes the flue gas of the shaft kiln produce inverted smoke. The more water is sprayed, the more serious the inverted smoke is. On the one hand, it limits the amount of water spraying and makes the flue gas emission difficult to meet the standard; On the other hand, it also makes the operating environment of the worktable on the surface of the shaft kiln bad, and CO poisoning accidents of workers often occur

in order to solve the problem of pouring smoke, people have made a variety of explorations and experiments. Installing axial fans in high-temperature gas flow chimneys will cause the burning of motors and bearings. Axial fans cannot be used in shaft kiln chimneys. Adopting the blower to blow into the chimney to improve the wind speed in the middle of the chimney can not solve the problem of smoke pouring from the chimney. In view of the above problems, a high-temperature axial flow fan with large air volume, high temperature resistance and large specification, which is suitable for shaft kiln water dust removal, is developed

2 determination of performance parameters

Figure 1 is the schematic diagram of installing high-temperature axial flow fan for water dedusting of shaft kiln. Each shaft kiln has two chimneys. Because the diameter of water deduster is large, the water content in flue gas is large, and the top position is high, the high-temperature axial flow fan is installed in front of water dedusting, and each chimney is installed with a high-temperature axial flow fan. In the production process of shaft kiln, the flue gas emission is 30000 ~ 60000 m/h, the total design air volume of two axial fans is set at 60000m/h, and the design air volume of each axial fan is 30000m/h. According to the field measurement, after the air flow passes through the spray tower, the pressure drops by about 220pa, and the air pressure of the axial flow fan is set at 250pa. Because the chimney diameter of most mechanical shaft kilns is Ф About 1.5m, considering the resistance of the pipe and the convenience of pipe connection, the shell diameter is required to be equal to or close to the chimney diameter, so when designing the fan impeller, the impeller diameter should be increased as much as possible. Because the impeller diameter of the fan is large, under a certain air volume and pressure, the speed of the fan will be reduced accordingly. A 6-pole motor with a speed of 960r/min is selected

it can be seen from the above that the performance parameters of the designed high-temperature axial fan should be total pressure P =250pa, flow Q =30000m3/h, speed n =960r/min

3 structural design

the design of high-temperature axial flow fan should consider the requirements of service conditions, reliable fan operation and convenient installation and maintenance. The high-temperature axial flow fan is connected in series in the pipeline, and the flanges at both ends of the casing are connected with the pipeline. The structure of the designed high-temperature axial flow fan is shown in Figure 2. The structural design should mainly address the impact of temperature on the axial flow fan, the cooling and lubrication of bearings, and the cleaning of blade dust. The fan works in high temperature (100 ~ 200C) and corrosive gas. In order to protect the motor, the direct connection between the motor and the fan is not used, but the belt drive is used. The motor is placed outside the casing, and the V-belt and the fan pulley are surrounded by steel plates to avoid direct contact with high-temperature airflow. The fan operates in a gas medium with high dust concentration and high humidity, so it is very easy to bond dust on the fan blade, which is detrimental to the fan operation. In order to remove the dust on the blade, set a cleaning door on the casing corresponding to the fan blade up to its broken piece, and the small door should be sealed with the cylinder wall

the fan bearing operates continuously under high temperature, so the lubrication and cooling of the bearing are very important. In terms of structure, reliable lubrication of bearings shall be ensured and water cooling devices shall be set. Figure 3 shows the cooling lubrication structure of the high-temperature axial flow fan. A cooling water jacket is set around the bearing to pass cooling water for cooling. Due to the vertical installation of the fan, the cooling water enters from the lower part of the fan and drains from the upper part. The main production technology of thin oil circulation for lubricating oil is "rolling embedded" ring lubrication, and the lubricating oil should also be cooled. In order to ensure the lubrication of bearings, a skeleton oil seal is set under each bearing to reduce the loss of lubricating oil

4 fan performance test

the processing and manufacturing of high-temperature axial flow fan was completed in the blower factory. After the completion of manufacturing, the fan performance test was carried out. After many improvements to the geometric parameters of fan blades, it was made to meet the design requirements. The air volume, air pressure and other main parameters of the axial flow fan have reached the design index. Through quality inspection, the processing quality of the prototype meets the technical requirements. The fan motor model is y 132M 2 -6, the power is 5.5kW, the rated speed is 960r/min, and the fan impeller diameter is 1280mm dynamic load testing machine: including impact testing machine, fatigue testing machine and impact Brinell and shore durometer in the hardness tester. Table 1 shows the fan performance test value

5 fan operation

in order to solve the serious pollution of smoke and dust emission to the atmosphere in the production of machine shaft kiln, Suiping cement plant shaft kiln adopts water dedusting technology, However, the spray water of water dedusting increases the flue resistance, and the amount of water spraying is small, which makes the water dedusting produce inverted smoke and cannot meet the discharge standard. After the developed axial flow fan for water dedusting of the shaft kiln is installed on the water dedusting equipment of the plant, the smoke exhaust capacity of the chimney is improved, the operating surface of the shaft kiln is clean, and there is no CO poisoning, which greatly improves the working environment of workers and is highly praised by workers. Increase the amount of water spray, so that the water dedusting can meet the discharge standard. The fan can operate stably under high temperature. The accumulated dust on the fan blades shall be cleaned when the shaft kiln is stopped for maintenance, which will not affect the work of the shaft kiln. The fan has been tested by smoke with high temperature, high humidity and high dust concentration. The practice shows that the fan can be applied to smoke exhaust of shaft kiln, which fills the gap in the application of axial fan in this field

6 conclusion

(1) the developed high-temperature axial flow fan solves the problem of smoke pouring from the water dedusting flue gas of the cement shaft kiln, and provides a good solution for the smoke discharge of the water dedusting flue gas of the shaft kiln

(2) the cooling, lubrication and belt protection structure of the fan enables the fan bearing and belt to operate safely under high temperature, the external motor prevents the motor from burning, and the cleaning door structure enables the fan to operate in high dust smoke, and the fan can operate smoothly under high temperature, high humidity and high dust

(3) the fan has large flow and low pressure, which meets the requirements of dust removal process

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