(1) online cleaning and offline cleaning.
what is the function of cyclone separator? Two methods of online or offline cleaning can be used. On-line ash cleaning means that the filter bag is still filtered for dusty gas when pulse injection is carried out. The injection system needs to use a relatively high injection airflow to block the filter flue gas, and at the same time make the dust layer on the filter bag peel off into the ash hopper with instant pulse oscillation. The inside of the online dust collector is a large space static air chamber, the air distribution is more uniform, so that the filter load under the filter material does not change too much, which can extend the service life of the bag.
The off-line dust cleaning system needs to divide the dust collector into several sealed bag rooms, and the air outlet on the flower plate of each bag room is independently installed with the shutoff valve, cylinder and solenoid valve and other compressed gas control systems. Before pulsed cleaning spray is performed on each bag chamber, the damper is first controlled to remove the flue gas filtration from the bag chamber. Therefore, the off-line cleaning mechanism is more complex, and there are related broken valves, so the cost and maintenance of the off-line dust collector is relatively higher than that of the online dust collector.
In fact, according to the nature of flue gas and process requirements, flexible selection of online or offline ash cleaning system design. In some special processes, such as waste incineration, the dust is loose and not easy to form cake, and it is difficult to effectively remove the ash. Using the method of dust removal can reduce the "secondary dust", make the dust removal stage more perfect, to reduce the effect of equipment resistance.
But on the other hand, after the dusting of a bag chamber is completed by the off-line dust collector, the filter bag resistance of the bag chamber will be lower than that of other air chamber filter bags being filtered. At this time, open the shut-off valve, the bag indoor filter bag will bear a high filtration load, resulting in a high load change cycle of the filter material, which will also shorten the service life of the filter material. While online cleaning only reduces the resistance of a line of filter bags each time, a large number of other bags inside the dust collector will continue to filter, so that the change of filtration load borne by the filter bag after just spraying is relatively mild. Therefore, if the dust collector treatment air volume is small, the internal structure can not be divided into 4 ~ 10 more bag room number, it is not suitable to use off-line dust cleaning. For the smoke flow covelocity, that is, the filter wind speed in the large dust collector, is generally below 1.5m/min. Compared with the inlet concentration of the dust collector, "secondary dust" is not a very serious phenomenon, so it is advisable to use online dust cleaning. For the general small and medium-sized dust collector (less than 100,000 m3/h treatment air volume) unit using online dust cleaning and timing or fixed pressure difference pulse control to ensure the dust collector resistance is more feasible.
(2) Pipe spray and box spray.
Tubular injection means that a spray pipe is set above each row of filter bags, and ash cleaning air is sprayed into each filter bag through the nozzle on the pipe. The spray aperture is different, which can ensure the uniform cleaning strength of each filter bag. Sometimes the nozzle aperture is the same to facilitate machining.
Box type injection does not have a blast pipe, cleaning air by pulse valve directly into the upper box and pressurized, and then transfer energy to each filter bag in the chamber to achieve cleaning. The experimental results show that the cleaning strength of each filter bag in different parts is different. The actual application of box type jet bag type dust collector generally has a large pressure gas consumption; Filter bag length is limited; The cleaning effect depends on the air tightness of the off-line valve. So box type jet is used for small and medium-sized bag type dust collector. But the advantage of box type injection is that bag changing operation saves the process of disassembling and installing the spray pipe, which can realize the rapid replacement of filter bag.
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