Talking about the new environmental standards baghouse dust emissions standards
Talking about the new
baghouse dust emissions
-- ZG Boiler
ZG is one of the largest CFB boiler company now, the company runs 30 plants in 25 using
baghouse. With the CFB boiler operating cycle increases, the gradual emergence of baghouse dust
emission concentration, increased the number of damaged bag, repair and maintenance costs of a
large, partially unit facing new environmental emission standards issues.
ZG have a project in China 4 × 200MW circulating fluidized bed boilers, low-pressure pulse bag
filter for dust removal system for the power unit configuration. Each furnace dust bag filter area of
24805 m2, designed to ensure that dust outlet dust concentration ≤50mg / m3.
Four sets of coal-fired circulating fluidized bed boiler precipitator bag limit reached almost
30,000 hours service life cycle, especially # 1, # 2 furnace is running higher than the average load,
longer running time, the bag elastic failure occurs in varying degrees , cracking the bag leaks, a
direct result of increased dust emissions. In Unit Level Maintenance and routine maintenance,
replacement of numerous other domestic manufacturers sporadic bag, bag filter dust poor
operating results, can not meet the national goal of the new environmental standards soot
emissions 30mg / m³ below. From visual inspection of the bag and the bag have been running
most of the data recorded on-site requirements can not be met, with the bag after changing
concentration of dust emissions can be reduced to between 30-40mg / Nm3 in the short run three
months later, the gradual concentration of dust emissions increases.
A chemical plant 2 × 150MW coal gangue power plant supporting the low-pressure pulse bag
filter has a flue gas channels, each two bags of room on each side, a total of four entire filter bag
house, each room a bag bag beam, each bag filter total number of 4944, total filtration area
16315.2 m2 / Taiwan. # 1 unit in October 2009 and put into production, in June 2011 flue dust
emission concentrations exceeding 586 check and replace the bag; October 2011 C-class
maintenance, replacement bag 133; May 2012 A-level repair, replacement damaged bag 250. # 2
boiler into operation in December 2009, April 2011 No.2 furnace repair, four bags of room to
replace the bag 613. Boiler during operation will often fall off the bag, resulting in poor ash.
According to two plants baghouse operating conditions, bag check and replace the previous
inspection and testing situation analysis, filter dust emission concentration shortly after the
overhaul increased primarily bag damage.
Causes damage to the bag
Failure and dust bag design, installation, operation, bag quality, scope and matching bag of smoke
conditions and other factors. The main reason for the failure outstanding performance: chemical
corrosion, mechanical damage and wear.
Chemical corrosion. Mainly due to the smoke-temperature, high oxygen content of flue gas into
the baghouse of SOx / NOx concentration is high, combined with water vapor, as shown in the
oxidation caused by corrosion of the bag, as shown in Figure 3. Another major form of chemical
attack is low acid condensation corrosion
Mechanical damage and wear is mainly due to the uneven distribution of flue gas, bag cage
installed incorrectly collision between each other, the injection tube is aligned relative errors
bag, bag breakage caused by high flue gas velocity.
(1) fly ash, smoke and wear. After the smoke into the bag unit chamber, in part due to the collision
of space between each other to produce a vortex of dust particles, the eddy current effect in the
majority of the outermost layer of the bag and the bottom of the vertical plane of the majority of
the bag, resulting in the majority of the bottom of the bag damaged, bag bag bag house edge than
the room in the middle of the bag breakage probability of large, gas entrance bag easily damaged
than the distance.
(2) replacement of sporadic no protective dust bag surface layer, it is vulnerable to ash erosion, oil
and other substances adhesion, resulting in blockage bag, the other bag output load increases
relatively accelerated bag damage.
(3) High Level cause bag breakage. Material level is too high, swamp bag, to a certain speed of
the flue gas flow through the bag to make contact with the Department of fouling generated
disturbances, so close to the bag at different levels of vortex formation gray ash concentration at
the contact coupled with relatively High exacerbated bag wear.
(4) the amount of wind uneven. Each bag regional uneven air flow, resulting in damage to the bag.
(5) the quality, but off the bag. Due to the poor quality manufacturers, sewing bag of a fracture
line, high-temperature damage, damage caused by the bag.
(6) When the bag is installed, bumps or scratches did not produce in time, lead to bruising running
scratches appear at the damage.
Measures to improve the life of the bag
Strengthen the operation and management of baghouse
After the dust before the repair and replacement bag for a larger number put into operation, must
be pre-spraying work; precipitator inlet flue gas temperature control in the flue gas above the acid
dew point 20-25 ℃, but not higher than 160 ℃, prevent flue gas bag chemical corrosion;
precipitator ash hopper material level can run high, gray level is too high to avoid flooding bag,
dust bag phenomenon leads to scour the bottom of the bag breakage occurs; boiler leaks, a timely
exit precipitator operation.
ESP repair and maintenance should pay attention
Precipitator before overhaul, application phosphors leak test, find out the leak, its total
elimination; for dust blocking plate flower board reserved cancel flower plate blocking plate, all
installation of bag ; bypass damper Mifengbuyan to be seriously improved bypass valve structure
to avoid leakage; carefully check the injection angle of the injection tube and bag, avoid airflow
deflection, resulting in damage to the bag of blow ; precipitator hopper level meter ground
inspection, ground maintenance, eliminate the phenomenon appears distorted; for sporadic
replacement bag, before installing the work should be pre-coated gray; the distribution of the bag
after the installation carefully check the bottom of the bag, on the reverse occurs, collision repair
bag reset; strictly enforce installation specifications when installing to avoid foreign body
transferred bag, bag cage clamp must be a good card, avoid the use of invalid clips; use the
opportunity to overhaul the precipitator ash hopper at about 1.5 m the installation of a large grid,
to prevent clogging after falling out of the bag gray; the boiler air preheater leakage, leakage filter
body to govern, so dust during operation, the oxygen content of not more than 6%; the damaged
filter Bag is unclear due to their own technical strength analysis conducted inspection analysis;
baghouse dust collector or replace the whole entire bag, choose professional installation team,
avoided due to the installation of non-standard bag, causing the bag mouth wear out bags, and
skeleton with the other issues.
Selection and smoke conditions suited to bag
Selection of the bag main factors to consider: temperature, flue gas composition of flue gas (such
as 02 content, NOX, SO2, SO3 content, H2O, etc.), the elemental composition of coal, the
chemical composition of dust, soot particle size distribution , dust concentration, the emission
requirements of the boiler type, soot and cost-effective.
Specification and procurement of innovative bag
When the bag escalation procurement plan, referring to the principle of selection bag, according to
the actual situation of the unit, the technical requirements must be clear; the bag when the material
procurement sector procurement, should manufacturers direct procurement, to select technical,
economic strength Strong and good after-sales service manufacturers to ensure the quality of the
bag; procurement to bag factory after random sampling inspection, the good customs inspection;
at the same time to strengthen the management of the whole life of the filter bag tracking, timely
will not meet the technical requirements of the filter clean out the bag provider vendor library.
Innovation precipitator (including bag) mode of operation and maintenance
Under environmental protection has become a veto power plants operating indicators, the plant
can try innovative bag procurement management practices, the use of retention money and quality
hooks bag use technology to reach agreement requires lifetime reward, etc., to encourage suppliers
Good quality bag. Can also consider the use of "Product + Services" model of cooperation, the
precipitator (including) the overall operation and maintenance of assigned to a certain technical
strength of bag manufacturers, to facilitate unified management.
Selection baghouse selection can achieve flue dust emission concentration <new environmental
requirements 30mg / Nm3 in. At present, our company within the scope of operations of the plant
put into operation baghouse emission standards beyond the design value or the value of new
environmental emission requirements, mainly due to dust bag failure during operation. To change
the current baghouse dust emissions big situation, the focus is to solve the problem of bag failure.