(1) One of the key factors influencing the lifespan of bag-type dust collectors is the control mode for back-blowing and dust removal frequency and intensity. Given the significant fluctuations in the load of power station boilers and the quality of coal combustion, the volume and dust concentration of flue gas can vary considerably. Consequently, when designing a back-blowing and cleaning system, it’s essential to incorporate multiple operational modes based on the pressure differential between the upper and lower chambers of the dust collector (the purified gas chamber and the filter chamber). This flexibility allows the system to adapt to the changing operating conditions of coal-fired boilers, thereby extending the service life of the dust collector.
(2) A common issue with bag-type dust collectors is the blockage of the ash hopper. These systems typically use a water-flush ash discharge method, where ash falls into the hopper and is transported via an electric airlock into an ash water tank before being discharged through a ditch. During winter, particularly when the boiler has been recently started or restarted after a prolonged shutdown, the ash hopper often becomes blocked. Analysis reveals this is due to condensation within the hopper and poor sealing of the electric airlock. In colder climates, the outdoor temperatures are low, causing the hot flue gas to condense on the cooler walls of the hopper. This creates a stagnant area where the flue gas cannot heat the hopper quickly, leading to ash sticking to the walls and causing blockages. Additionally, if the electric airlock isn’t tightly sealed, moisture from the ash tank can be drawn into the hopper, further exacerbating the problem. Condensation around the ash outlet is another contributing factor. To address these issues, careful consideration must be given during the design phase to calculate the appropriate power and placement of the hopper heating devices, factoring in local temperatures and ash discharge methods. A preheating sequence should be integrated into the bag start-up control. Moreover, a reliable and well-sealed airlock should be chosen, and the insulation of the hopper should be enhanced.
(3) Common errors in the back-blowing and dust-cleaning system include malfunctioning back-blow solenoid valves, water accumulation in compressed air lines, and jamming of the rotary mechanism. The primary cause of solenoid valve failure is often a quality issue with the valve itself. However, the quality of the compressed air used (especially moisture and dust content) and the stability of the power supply can also impact the valve's performance. In northern regions during winter, the low outdoor temperatures can lead to water accumulation or freezing in exposed compressed air pipes. Thus, when designing such systems, drainage points and insulation measures should be incorporated, with additional heat tracing added in extremely cold areas. The rotary mechanism experiences varying temperatures, operating partly in high-temperature flue gas and partly in ambient conditions. This large temperature differential can lead to deformation and jamming, so thermal considerations must be thoroughly addressed in the design process.
In conclusion, optimizing the control of back-blowing cycles, ensuring proper hopper design, and addressing mechanical issues are critical steps in maintaining efficient and reliable operation of bag-type dust collectors, especially in challenging environmental conditions.
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