pulsed bag filter with its handling of large air volume, the system resistance is small, clean thoroughly, some desulfurization and fluoride function, high efficiency dust removal, favored by the majority of users in the dust market has been widely used.
however, many dust collectors in the use of the process are more or less there is condensation phenomenon. such as improper solution, will make the corrosion of the precipitator intensified, filter bag hydrolysis, shorten the life of the precipitator, serious dust can be bonded to the bag surface clogging the pores of the filter bag, resulting in dust resistance increased sharply until can not run.
first, the cause of condensation analysis
the so-called condensation, in layman's terms, refers to the wet air in a certain pressure and temperature, precipitation of saturated water phenomenon. the temperature of the precipitation of water is called dew point.
the higher the gas pressure in the saturated state, the lower the dew point. the higher the moisture content in the air, the higher the dew point temperature. when the moisture content in the air is constant, the temperature of the humidified air is lower than the temperature of the dew point, the water will precipitate in the supersaturated air, that is, the condensation will occur; when the air temperature is higher than the dew point will not precipitate water, does not produce condensation phenomenon. in addition, if the flue gas contains so2 components, the more so2 content, the higher the dew point of the flue gas.
second, the pulse bag filter condensation causes
1. there is leakage phenomenon of dust collector
due to the existence of leakage phenomenon of dust collector, the outside will be a lot of cold air into the dust collector, the precipitator local air temperature dropped sharply, the air in the water precipitation, resulting in condensation phenomenon.
resulting in a lot of dust leakage causes, there is a dust collector shell in the production process there is leakage caused by the phenomenon of leakage caused by leakage of the device caused by leakage of air leakage, non-standard pipeline in the installation process there is leakage caused by leakage phenomenon, there are dust and non-standard pipe flange connection caused by tight air leakage and so on.
2. the moisture content in the flue gas is too high
when the moisture content of the treated flue gas is too high, the supersaturated water is precipitated, resulting in condensation. this phenomenon is particularly prominent in the kiln dust collector of the dry line of cement. since the flue gas in the dry kiln of the cement is usually cooled and quenched and tempered by the humidification tower, when the amount of water sprayed is too large, moisture produces condensation when condensation occurs.
3. the flue gas temperature is too low
dust can also produce condensation when the temperature of the flue gas itself is close to or below the dew point.
4. pulse injection gas temperature is too low
the dust collector uses compressed air during the pulse jet cleaning process, while the compressed air itself is saturated air with a relative humidity of 100%. because of its air pressure is greater than atmospheric pressure, conversion to atmospheric pressure dew point than the ambient dew point is low, there is a tendency from the condensation. when the compressed air temperature and the internal temperature of the dust collector is not much difference, generally do not produce condensation phenomenon.
but in the winter, especially in the northern part of china's winter temperatures are usually in the minus ten or several degrees, the pulse of compressed air and dust inside the flue gas temperature difference is too large, in the compressed air instantly into the filter bag the temperature also will drop significantly, usually white mist spray condensed water mist high-speed airflow, the nozzle below a certain distance within the low temperature, the formation of low temperature zone.
as the compressed air in the nozzle is saturated air, the temperature drop after the gas is discharged will cause the area to be precipitated and cause condensation. at this time the condensation is mainly concentrated in the surface of the bag, the dust attached to the surface of the filter bag due to absorption of condensation of water and produce adhesion, and then plug the pores of the filter bag, resulting in dust can not work properly.
5. the dust collector shell is not insulation or poor insulation measures
the shell of the precipitator is generally made of steel plate, and the thermal conductivity of the steel plate is very large. when the temperature of the outside air is different from the temperature of the inside of the precipitator, the dust of the dust collector will produce condensation. if the dust collector's case does not take thermal insulation measures, or although the use of thermal insulation measures, but the effect is poor, the dust condensate condensation phenomenon is inevitable.
third. the pulse bag filter condensation solution
1. to reduce the dust leakage phenomenon
(1) dust collector in the production and installation process, to strictly enforce the jc / t532 welding standards for welding, to prevent the phenomenon of less welding, leakage welding.
(2) the discharge of the dust collector should be used to seal the good performance of the wind lock device, the current mainly to pneumatic or electric lock valve-based. if necessary, a two-stage locking device can be used.
the air leakage rate of a pulse bag filter should be controlled within the range of ≤ 3%.
2. strictly control the amount of water spray tower
when the cooling line of cement dry kiln is used in the humidification tower, it is not possible to strictly reduce the water spray of the humidification tower in the case of ensuring the temperature of the dust collector. humidification tower as far as possible the use of high-quality spray gun, so that the water spray fine uniform, with the least amount of water to achieve the best cooling and tempering effect.
3. stable flue gas temperature in a small range
when dealing with the high temperature of the flue gas, must immediately take to reduce the operating temperature, put the cold wind and other cooling measures; when the flue gas temperature is low, must immediately take to increase the operating temperature and other measures. so that the flue gas temperature can be stabilized within the specified range, to ensure the normal and stable operation of the dust collector to reduce the condensation phenomenon.
4. to reduce the pulse jet gas and the internal temperature of the dust filter and dehumidification treatment
the current domestic compressed gas commonly used air supply route is mainly: compressed air - gas tank - gas triple - air bag - pulse valve. this gas supply has the advantage of less investment and simple equipment, but when the outside air temperature is too low, the compressed gas is not fully treated and easy to be dew.
when the outside air temperature is too low and the air pressure station is far away, the air supply route can be used: compressed air - gas tank - air supply triple - air dryer - air heater - air bag (gas covered with insulation materials) - pulse valve. this gas supply way to wet full, thoroughly, pulse injection gas and dust inside the dust of the small temperature difference, not easy to produce condensation.
when the air pressure station is not far away, air source triple air filter can meet the needs of dehumidification, as long as the attention of the air filter near the air bag can be, so you can save the air dryer this link. when the temperature is too low, the gas pipeline, air bag and pulse valve must take insulation measures to prevent the condensation of compressed air and dust generated condensation.
5. to strengthen the dust collector insulation measures
dust collector shell must take thermal insulation measures, dust collector insulation generally used rock wool, aluminum silicate, pearl expansion rock and other thermal conductivity is low, good insulation performance, low water absorption, good heat insulation properties of insulation materials. the thermal conductivity of the material is generally not more than 0.23w / m. k. the thickness of the insulation material should be based on the geographical location, the local minimum temperature, the annual average temperature may be, according to the "control unit heat loss method" calculation formula to determine.
four, summary
in short, the pulse bag filter condensation for many reasons, we have to fully study the causes of dust condensate condensation, fully aware of the dangers caused by condensation to the dust, and effectively take effective insulation measures, and strive to dust the condensation phenomenon is controlled in the lowest range, so that the pulse bag filter can be long-term, stable operation.
(editor: kongxue ling)
article source: http://www.ccement.com/
