Bag failure

The effect of bag failure on bagliouse fractional penetration (or efficiency) can be described by tlie following equation ... 

For a detailed development of tlie above equation, refer to Effect of Bag Failure on Baghouse Outlet Loading, L. Tlieodore and J. Reynolds, JAPCA, August 1979, 870-2. 

Calculate tlie number of bag failures tliat tlie system can tolerate and still remain in compliance ... 

Tlie importance of when to correct/replace a broken bag will depend on tlie type of collector and tlie resultant effect on outlet emissions. In inside bag collection types of collectors, it is very important tliat dust leaks be stopped as quickly as possible to prevent adjacent bags from being abraded by jet streams of dust emitting from tlie broken bag. Tliis is called tlie domino effect of bag failure. Outside bag collection systems do not liave tliis problem, and tlie speed of repair is delennined by wlietlier tlie outlet opacity litis e.xceeded its limits. Often, it will take several broken bags to create an opacity problem mid a convenient maintenance schedule can be employed instead of emergency maintenance. ... 

It is important to note that each bag in a set may have a different life as a result of fabric quality, bag manufacturing tolerances, location in the collector, and variation in the bag cleaning mechanism. Any one or a combination of these factors can cause bags to fail. This means that a baghouse will experience a series of intermittent bag failures until the failure rate requires total bag replacement. Typically, a few bags will fail initially or after a short period of operation due to installation damage or manufacturing defects. The failure rate should then remain very low until the... 

In either type of collector, the location of the broken bag or bags has to be determined and corrective action taken. In a noncompartmentalized unit, this requires system shutdown and visual inspection. In inside collectors, bags often fail close to the bottom, near the tube sheet. Accumulation of dust on the tube sheets, the holes themselves, or unusual dust patterns on the outside of the bags often occurs. Other probable bag failure locations in reverse-air bags are near anticollapse rings or below the top cuff In shaker bags, one should inspect the area below the top attachment. Improper tensioning can also cause early failure. 

Having recently attended a class on the effects of bag failures given by the foremost authority in this field, you are asked to determine if the loss has been caused by broken bags, and, if so, how many have broken every month. 

The baghouse problem appears to be bag failure. Note that the effieiency drops below 90% after just 2 months. 

The reader should consider whether the bag failure distribution with time is reasonable. 

Up to 400MN/m (4000 bar) most isostatic presses work on oil/water emulsions or hydraulic oil for higher pressures, special fluids may have to be used. The tool material must be compatible, which can be achieved, but problems may arise if it becomes necessary to dispose of contaminated fluid. Such contamination can originate from powder adhering to the external tool walls or from tool bag failure. 

The key to baghouse maintenance is the frequent and routine inspection of the filter bags. All bag units have a finite lifetime. Typical causes of bag failure are [42] ... 

The collection efficiency of bag filters for various dust particle sizes is given approximately in Fig. 3.5-13. These collection efficiencies are realized for bags in good condition with miniit holes. The wearing of bag fabric is a severe problem and means should be provided to check the filter performance to detect bag failures before they become catastrc ic. 

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