The so-called mechanical wear is related to the processing, transportation, installation and steel structure design of the bag filter. Usually problems occur, such as small outer diameter of the dust removal skeleton, small number of vertical bars, large spacing between transverse bars and so on, resulting in squeezing force between the dust removal bag and the bag cage, which will break the dust removal bag during transportation and installation. Scratch and other phenomena are unavoidable in the process; concentricity between the nozzle and the orifice of the pattern can not reach the requirement or the perpendicularity between the nozzle and the pattern is not enough, which leads to compressed air blowing directly to the filter bag during the injection process, which causes the filter bag to be damaged by the impact force on the part of the filter bag; burr on the surface of the bag cage. The separation of the convex part or the connecting part of the two sections leads to intermittent wear and tear on the filter bag during the reciprocating process of filtration and dust removal; the poor matching between the filter bag and the flooring plate, such as the filter bag opening is not fully expanded or there is a gap between the bag opening and the flooring plate, causing the dust to wash the bag opening; the flooring has a notch or concave-convex, dust removal. If the joint of the filter bag is not standardized, it will also appear the phenomenon of "running ash". When the filter bag contacts with the reinforced section steel or the residual lug on the wall, the impact wear will be caused by the swing of the filter bag in the course of cleaning because of the lack of flatness of the ceiling or the inadequate verticality of the bag cage. Solution: The design, processing, transportation and installation process should be carefully organized, the quality of supporting parts should be strictly checked, the dust collector should be thoroughly checked before commissioning, as far as possible to reduce the workload of on-site installation, and equipped with related facilities, the higher quality requirements as far as possible by the production workshop.
Flue gas scour
The flue gas scouring is related to the structure design of the dust collector. The main reason is that the velocity of flue gas reaching the filter bag is too high. The dust carried by the flue gas scouring the filter bag directly leads to the wear of the filter bag. Especially when the dust concentration is high or the dust deposits appear in the inlet passage of the dust collector, this phenomenon will occur more easily. The wear area of the dust collector with downdraft is usually at the bottom of the filter bag. The wear area of the dust collector with horizontal inlet is usually at the front of the filter bag. Although a thickened layer is used at the bottom of the filter bag, this problem can not be fundamentally avoided.
Solution: Establish reasonable flue gas flow field, adopt necessary diversion and equalization measures, adopt multi-directional air inlet mode, form the trend of flue gas spreading over the whole filter area, ensure that the air velocity when flue gas reaches the filter bag is less than 1 m/s, at the same time avoid dust deposit in the inlet channel of the dust collector and the ash caused by poor ash conveyance in the ash hopper. The phenomenon of excessive occurrence occurs.
The blockage failure mainly includes three types: dust blockage, oil mist blockage and dew condensation pouch. Dust blockage is mainly caused by insufficient thorough dust cleaning, especially when the boiler is under low load for a long time not clean dust will also lead to this problem, fine dust swimming on the surface of the filter bag, in the process of filtration due to the dust squeeze between the dust into the filter bag fiber sandwich, resulting in dust immersion, causing With the increase of the local inherent resistance of the filter bag, the uniformity of the whole filter bag has changed, which not only causes the increase of the resistance of the filter, but also changes the filter path of the flue gas, increases the filter load of the unblocked filter bag and aggravates the deterioration of the filter bag condition. It is difficult to solve the problem that the filter bag is not properly protected or not properly protected during boiler start-up or low-load operation. The dew and paste bag is mainly operated below the acid dew point and the condensed acid adheres to the filter bag. This phenomenon mainly occurs on the outside surface of the filter bag when the boiler starts up because of low flue gas temperature or large area tube burst. The condensation paste bag will also increase the inherent resistance of the filter bag, and may also lead to acid corrosion of the filter bag.
Solution: Choose a reasonable structure type of ash removal system, set a reasonable dust removal pressure, dust removal cycle and ash removal control mode, to ensure that the ash removal is relatively thorough, avoid dust blockage phenomenon, especially attention is that excessive ash removal is not desirable, because excessive ash removal will affect the life of the filter bag and dust removal. Filtration performance; dust filter bag should be pre-coated before putting into operation, and a dust layer should be formed on the surface of the filter bag beforehand, which can block the encapsulation of oil mist and acid, avoid the direct contact of oil mist and acid with the filter bag surface, and avoid the phenomenon of oil mist blocking and dewing and pasting bag when the boiler is in low load operation. When oil is needed to assist combustion, the cleaning pressure and frequency should be lowered so that a certain thickness of dust layer remains on the surface of the filter bag to protect the filter bag. When the boiler bursts in a large area, when the humidity is more than 15%, it should consider stopping the furnace or opening the filter bypass.
High temperature damage
High temperature damage is mainly caused by high temperature dust particles on the surface of PPS filter bag. Dusty gas carries dust particles of different sizes. Cooling measures usually only achieve the cooling of gas temperature and fine particles. Because of the high velocity of air flow and limited cooling space, coarse particles often enter the dust removal system without cooling in time. High temperature coarse particles are intercepted and cooled on the surface of filter media. Particles at this temperature are intercepted and cooled. Generally, high temperature Mars causes local thermal damage on the surface of filter material. In case of project, flue gas temperature is always satisfied.