What should be done if the impeller of the boiler exhaust fan is frequently covered in ash?

Are your exhaust fans operated in a one-in-one-backup configuration? If so, the flue dampers at the inlet and outlet of these exhaust fans can be closed, after which an access hole can be opened on the fan casing to clean it using high-pressure water. . . Try turning it again to shake out the water. . . This method is for reference only; anyway, that’s how we used to do it

I also want to ask: do your dust collectors use electrostatic dust removal, water film dust removal, or bag dust removal? . ? ? ?

Water film dust removal Water film dust removal Water film dust removal

Original content for discussion: 1) Gravity settling. The measures are to increase the height of the water film tower, or to add gravity sedimentation chambers (tubes) in the flue. Given the actual circumstances, we believe that the renovation work is extensive and costly, and it would also increase the system resistance; therefore, we did not pursue this approach for further actions. 2) Online dust cleaning device. (A patent from Northeast Electric Power Institute in 1996) The solution involves introducing an air supply pipe at the fan inlet, and installing blowing nozzles symmetrically inside the fan to continuously clean the non-working surfaces of the impeller, thereby extending the period between dust accumulation on the impeller. Through physical measurements of the fan impellers currently in use, it was found that if this approach were applied to modify the existing fans, the air supply ducts would be very close to the impellers; any deformation in such ducts could potentially damage the impellers, which is why this modification was not carried out. 3) Adopt a fan impeller structure that is resistant to dust accumulation. Currently, the impeller structure of the exhaust fan is of the backward-curving type; fans with this design have high efficiency, but they are not suitable for use in dust removal systems with high levels of dust. In light of this situation, we contacted Dr. Tan Houzhang, an expert from the School of Thermal Engineering at Xi’an Jiaotong University. Tan has previously modified the impellers of dozens of induced draft fans in China by replacing them with arc-shaped impellers, which enables the imbalance period of the impellers to be extended to over three months while maintaining efficiency. However, a specialist must be on site to carry out the measurements and design, and the cost is 150,000; the renovation is quite expensive. According to available information, the traditional impeller design used in environments with high dust levels is the straight-plate type impeller; the drawback of this design is its lower efficiency. Sichuan Shangfeng Ventilation and Air Conditioning Co., Ltd. (formerly Chuanbei Fan Factory) was commissioned to submit a renovation plan for fan impellers with a slightly curved shape that resembles a straight plate; this plan aims to maintain the efficiency of the fans while effectively extending the period between dust accumulation on the impellers. Discussions regarding this renovation project are currently in progress. 4) Cyclone separation. The measure is to add a cyclone separator in the flue. Based on past usage experience, cyclone separators made of metal tend to wear out easily and are difficult to maintain. The water film tower currently in use is designed based on this concept; we believe that making the most of the existing equipment under current conditions is the key to extending the period between dust accumulation on the impellers. 5) Improving the efficiency of the water film dust removal system may reduce the amount of dust that enters the induced draft fan. Based on the existing two nozzles in the venturi of the water film dust removal system, two additional direction-finding nozzles were added, which improved the atomization effect and reduced dust accumulation in the venturi, thereby also decreasing the amount of dust that reaches the induced draft fan ； Two manholes were installed in the marble flue at the top of the venturi nozzle to facilitate inspection and cleaning without shutting down the furnace ； The wear-resistant baffle has been changed from 300 mm wide to 100 mm wide, which effectively increases the cross-sectional area of the flue without compromising the wear protection effect for DN80 water pipes; this helps to prevent blockages and reduce the energy consumption of the exhaust fans.

When purchasing a fan, it is better to consider a fan with a low rotation speed for this purpose.

It is possible that the dust collector is not working properly; therefore, the ash accumulated on the blades of the induced draft fan should be removed promptly. When doing this, pay attention to changes in the main steam temperature and adjust the amount of water used for temperature reduction accordingly. It is also possible to turn off all the water used for temperature reduction. If two boilers are operating simultaneously, the other boiler can be used to maintain the steam temperature and pressure in the boiler being cleaned. Keep in close contact with the turbine operator, as otherwise, if the steam temperature drops below a certain level, the system will shut down, leading to an accident.

This post was last edited by lhooam on 2018-6-6 at 11:33. Ultrasonic speakers can address the problems of excessive vibration that leads to shutdown of fans due to dust accumulation on the impellers, as well as the need for manual cleaning of air ducts – provided by Liaoyang Kexing Instruments

Absolutely comprehensive. Could you give a brief introduction to the thermodynamic conversion of water films?