Analysis of fan modification by Shengyuan Technology:
The outlet pressure of the primary fan is controlled at around 56kPa for a long time, the flame is weak, the working conditions are not ideal, the air regulation of the coal pipe is limited, and there are often severe sand flying in front of the kiln, high temperature at the kiln tail, poor quality of clinker, severe skin formation in the preheater system, and frequent blockage. The negative pressure fluctuation at the kiln head is large, and the power consumption of the primary fan is as high as 110kW or more.
After analysis, it is believed that the main reasons for the above problems are the high amount of head coal and insufficient combustion of coal powder. The incomplete combustion of coal powder causes a severe reducing atmosphere in the kiln, and the FeO reduced from Fe ₂ O3 is prone to form low melting point compounds with other oxides, resulting in the formation of rings and continuous detachment of the secondary kiln skin, causing thermal system disorder.
Firstly, improvements were made in the ingredients and process operations, appropriately increasing the clinker saturation ratio and silica content. While ensuring the kiln condition, the amount of head coal was appropriately reduced, and the fineness of coal powder entering the kiln was lowered. After taking the above measures, the situation of system crust blockage has improved to some extent, but the problems of high kiln tail temperature and severe reducing atmosphere caused by incomplete combustion of coal powder still exist. Insufficient air pressure, poor coal powder dispersion effect, and poor air coal mixing are the fundamental reasons for incomplete combustion of the head coal. Therefore, it is necessary to increase the outlet air pressure of the fan. At present, the primary fan is operating at full load. In order to reduce the power consumption of the fan, considering the mechanical characteristics of the Roots blower that the higher the speed, the greater the air volume and shaft power consumption. After comparison and evaluation, the company has decided to use an air suspension fan for energy-saving transformation, increase the air pressure and speed, and reduce operating power consumption. This can not only make the flame bright and powerful, fully burn coal powder, but also increase flame toughness and stiffness, reduce secondary air impact, reduce negative pressure fluctuations at the kiln head, and improve system production quality.
During the renovation process, the backup fan of the original primary fan will be removed, and an air suspension fan will be installed on the original fan base. The original backup fan pipeline will be removed, and the overall design and installation of the suspension fan outlet pipeline will be carried out. When starting the air suspension fan, a high speed of 24000 r/min must be maintained, and the speed during operation should be controlled between 24000 and 27000 r/min. Therefore, two air discharge pipeline valves, namely the residual air exhaust pipeline and the bypass pressure relief pipeline, will be added to the air suspension fan. The function of the residual air exhaust pipeline is to automatically open the exhaust valve when the fan pressure sensor fails or the outlet valve is excessively operated to close, preventing damage to the internal structure of the fan caused by high air pressure. At the beginning of ignition, the fuel volume is relatively small. To prevent the outlet air pressure from being too high when the fan runs at a high speed of 24000r/min, the pressure relief valve needs to be manually opened to adjust the outlet pressure of the fan and create a strong and powerful flame. In the process of gradually increasing the coal consumption at the kiln head to normal operation, the opening of the pressure relief valve should be gradually reduced to zero. The existence of the pressure relief valve is crucial for the ignition and heating system of the kiln and should not be cancelled. Install silencers on two air discharge pipelines to reduce noise pollution, and use the original primary fan as a backup fan for the air suspension fan.
The transformed air suspension centrifugal blower takes the dynamic air bearing technology as the core, high-speed fluid machinery as the support, and adopts the design of dynamic air bearing, high-speed permanent magnet motor, high-efficiency impeller and automation system, which perfectly solves the problems of great energy loss and noise caused by the friction of the flash machine, and can provide sufficient air pressure and wind speed for the kiln burner. The air suspension fan is integrated and compact, easy to install and operate, and has the characteristics of advanced technology, reliable performance, simple structure, small size, energy saving and convenient maintenance.
