Li

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 84-GT-39

345 E. 47 St., New York, N.Y. 10017
^+ The Society shall not be responsible for statements or opinions advanced in papers or in
C S
J discussion at meetings of the Society or of its Divisions or Sections, or printed in its
(y^ publications. Discussion is printed only if the paper is published in an ASME Journal.
^lL Released for general publication upon presentation. Full credit should be given to ASME,
the Technical Division, and the author(s). Papers are available from ASME for nine months
after the meeting.
Printed In USA.
Copyright © 1984 by ASME

EXPERIENCE IN THE OPERATION OF AIR FILTERS IN GAS TURBINE INSTALLATIONS

T. Zaba, Deputy Manager, Gas Turbines

P. Lombardi, Consulting Engineer, Gas Turbines

BBC Brown, Boveri & Co. Ltd.

CH-5401 Baden/Switzerland

ABSTRACT INTRODUCTION

Industrial gas turbines swallow air at a Air inlet filtration systems are used
rate of approximately 14 to 16 kg/kWh. Even to protect the gas turbine against fouling,
in clean environments the amount of solid erosion, corrosion and foreign object
particle ingestion is significant. A damage.
70.000 kW gas turbine operating in a typical
residential area could ingest 1.3 to 1.5 kg Fouling
of solid contaminants in a 24 hour period.
The same gas turbine operating in a typical Fouling is the degradation of efficiency
mining or oil field region could ingest 33 to and flow capacity caused by the adherence of
39 kg of solid contaminants in a 24 hour particle matter/contaminants to the surface
period. Depending on the composition, size, of the turbomachine blading. Fouling, which
quantity and condition (wet, dry, sticky) of can normally be reversed by cleaning, can
the ingested particles, performance loss, occur in the compressor and/or turbine. The
due to the fouling of the compressor and/or contaminants that cause compressor fouling
turbine and hardware deterioration, due to enter the gas turbine with the inlet air.
erosion, corrosion and/or foreign object The contaminants that cause turbine fouling
damage, can be experienced. can enter the gas turbine with the inlet
air, the fuel, fuel additives or NO x control
To protect against performance loss and injection fluid.
hardware deterioration, industrial gas
turbines are normally equipped with air All compressors are susceptible to foul-
inlet filtration systems. However, the ing with the degree and rate of fouling de-
effectiveness of the filtration system pending on the type and condition of the
depends on how well it is matched to the airborne contaminants, the site environment
contaminants and site conditions. Matching and climatic conditions. Compressor fouling
the filtration system to the contaminants is generally caused by particle matter of
and site conditions is usually a judgement 5 ism in diameter or less. Whether turbine
decision based on experience and available fouling, if it should occur, is caused by
information. This paper was written in an airborne contaminants,depends on the ability
effort to enhance the equipment selection of the airborne contaminants to reach the
process by reviewing BBC's experience with turbine section and on the ability of these
air inlet filtration systems. contaminants (together with fuel ash) to
adhere to the turbine blading.

A theoretical and experience related

review of the impact of fouling on gas
turbine performance can be found in Ref. [1].
Data presented in reference 1 indicates
that fouling which results in a 5 % re-
duction in the compressor flow capacity

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use

 will also yield a reduction of about 2.5 % in the compressor blading is required to protect
compressor efficiency, a reduction of about against wet corrosion; this is particularly
10 o in gas turbine power output and a re- true when gaseous contaminants are present.
duction in gas turbine efficiency of about
5 o Fig. 7. The fouling trends can be assumed The quantity of corrosive elements that
to follow a linear characteristic. can be allowed to enter the gas turbine
through the air stream depends on the choice
Frncinn of fuel. The total amount of corrosive ele-
Erosion is the abrasive removal of mate- ments coming from the air stream, water/
rial by hard particles suspended in the air steam injection and fuel must not exceed the
or gas stream. Particles causing erosion are limits set by the turbine manufacturer's fuel
normally 10 um or greater in diameter. The specification. A discussion on this subject
particles between 5 and 10 um fall in a and related topics can be found in Ref. [21.
transition zone between fouling and erosion.

The compressor blading shown in figure 1 Foreign Object Damage

exhibits particle erosion and fouling. Refer-
ring to figure 1, severe erosion of the blade Foreign object damage is caused by large
tips, location A, can be observed in the objects impacting the internal components of
first rotating blade row. The blade rows the engine. The objects enter the gas turbine
that follow display a lessened degree of through the air inlet and normally cause
erosion, location C, on the blade tips, but damage to the early stages of the compressor.
erosion of the blade tips can increase in However, there have been cases where a for-
the last stages as the particles are centri- eign object worked its way through the early
fuged outward. The portions of the blades stages of the compressor and caused damage
close to the rotor have a rough coating, in later stages. The amount of damage an
location B, that was intensified by the high object can cause depends on the size and
moisture content in the air. composition of the object, on the blade
construction, and on the location on the
blade the object strikes. Foreign object
damage can lead to direct failure and exten-
sive secondary damage.

ACHIEVABLE RESULTS

With the proper application of air inlet

filtration the following positive results
can be achieved.

1. Elimination of foreign object damage.

2. Reduction in erosion.

3. Reduction in high temperature corrosion.

4. Reduction in wet corrosion caused by

Fig. 1 Compressor rotor with erosion and salt and other solid particles.
fouling at different regions of (The filtration system will offer little
blading protection against the attack of gaseous
contaminants.)

('n r fin cinn 5. Reduction in the fouling rate of the

Corrosion is the loss of material caused compressor or turbine.
by chemical reaction between engine compo-
nents and contaminants which can enter the 6. Increase in the time period between clean-
ing or washing the compressor or turbine.
gas turbine through the air stream, fuel
system or water/steam injection system.
Elements such as sodium, vanadium and lead, 7. Lessening of the possibility of fouling
in metallic or compound form can lead to induced surge.
high temperature corrosion, especially in
the turbine blading. Salts, mineral acids 8. Better utilization of the engine power
capacity and efficiency.
and aggressive gases, such as C12, in combi-
nation with water can cause wet corrosion
accompanied by pitting, especially in the 9. Extension of component life, especially
compressor blading. Quite often coating of compressor and turbine blading.

10. Overall reduction of maintenance cost.

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use

 Hi

The elimination of foreign object damage Recently, use has been made of self-
and erosion are the only absolute gain that cleaning filters, referred to as pulse fil-
can be achieved with air inlet filtration. ters. In addition to high efficiency separa-
All other gains are less than absolute be- tion, these filters are reported to have
cause existing air inlet filtration systems longer life expectancy than other air inlet
are not able to eliminate 100 % of the air- filter systems.
borne contaminants.
Electrostatic filters have also been
used successfully in the past. BBC employed
HISTORICAL OVERVIEW electrostatic filters on gas turbine in-
stallations burning low BTU blast furnace
The effect of fouling of an axial com- gas.
pressor was first measured in 1936. A coating
of about 0.1 mm was applied to the blading
of a relatively small machine. The reduction ELEMENTS OF THE AIR INTAKE SYSTEM
in flow capacity was found to be about 10
and the reduction in compressor efficiency Figure 2 schematically shows the most
about 5 %, very similar to current experi- important elements of the air intake system
ence. for stationary gas turbines. Normally the
weather shield and inlet silencing baffles
The first air filters used on gas turbine are always included.
installations were stationary oil-coated The screen element should also be in-
elements. They required a great deal of main- cluded to protect against bird ingestion
tenance and a shift was soon made to oil- and other large foreign object ingestion.
coated endless rotating belts of metal The bypass arrangement is used when there
elements. Contaminants are removed from the is a danger of icing or filter clogging. If
filter elements and the oil coating replaced there is a threat of icing, the inlet air,
by the rotating oil bath filters. wherever possible, is preheated before it
reaches the filtration system i3I. In certain
In conjunction with the development of cases evaporative cooling, not shown in
plastics, the next generation of filters figure 2, is used to reduce the inlet air
introduced were the moving media roll-type. temperature.
These filters consist of two reels. One reel
containing the unused rolled filter media
and the other reel, the take-up reel, con- THE EFFECT OF HUMIDITY
taining the used media. The filter media ad-
vances as a function of the pressure drop A high relative humidity can accelerate
registered across the media. the process of fouling. In front of the first.
Inertial filters were developed in rotating row in the compressor, the air is
parallel with the roll-type filters. The accelerated to about 200 m/s, which entails
primary purpose of these filters is to remove a reduction in static temperature of about
large, 10 um or greater, particles from the °
20 C f31.
air stream to reduce the possibility of
erosion.

The next step in the development of air

filtration systems was the application of
high efficiency filter elements. High effi-
ciency elements are generally of the deep
bed or surface type.

To extend the life of inlet filtration

systems and reduce maintenance cost,current
practice is to stage filtration elements.
Two and three stage systems have been em-
ployed. Two stage elements normally consist
of a sturdy filter capable of removing large
particles, 10 um and greater, and high effi-
ciency filters. The initial filter reduces
the contaminant load that must be handled Fig. 2 Elements of the Air Intake System
by the high efficiency filter. Three stage
elements normally consist of a sturdy filter, 1. Weather shield 5. Bypass
capable of removing large particles. 10 pm 2. Screen 6. Silencer
and greater, an inexpensive pre--filter and 3. Self-cleaning filter 7. Air preheater
a high efficiency filter. Multi-stage filter 4. Second stage filter 8. housing
elements will be discussed in more detail
later.

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use

 L

Figure 5 shows the relative surface

area of the dust particles as a function
of their diameter. It also shows the change
in the surface area after the filters. It
can be seen that the reduction of the sur-
face area brought about by the filtration
is relatively small, which can be a reason
why a significant reduction in the fouling
of the compressor blading with air filtra-
tion can only be attained with the use of
very high efficiency filters.

FILTER SELECTION CONSIDERATION

Local conditions with regard to dust,

environment and climate place different
demands on the air filtration system. The
shift in seasons, periods of rain, sand-
storms or snowstorms, changes in dust com-
position, insects, organic materials
(pollen, residues of cotton, leaves) must
enter into consideration.

1 23 4 5 z0

airborne dust,

Fig. 3 Change in the Saturation Temperature dust s paration

n prefilter
at the Compressor Inlet
10 dust separation
T asstatic air temperature n postfifter -

T saturation air temperature

dust at
0 relative air inlet humidity compressor-inlet -^

0
0,01 0,1 1 10 µm
Figure 3 shows the change in the static particle size
air temperature, T as , at the entry into the
compressor blading. Figure 3 also shows the
change in the saturation temperature of the
air, T s , with various relative humidities
before the compressor. As an example, when
the relative humidity of the air, 0, is 0.6, Fig. 4 Dust Particle Distribution in the
the air temperature, T as , is lower, shaded Two Stage Filtration System
zone of figure 3, than the saturation tem-
perature T s , and this can cause condensation
of the water vapor. When this happens, the
dust particles serve as nuclei for conden- r-borne dust
sation, and become damp, which speeds up the z0
dust separation
process of forming deposits. During the course n prefilter

of compression, the air becomes warmer and \ dust separation

drier, which leads to a reduction in the Y - in postf"ter

fouling in the last rows. dust at

I
compressor islet
r 10

MULTI-STAGE FILTRATION
a
If a high degree of dust removal is
called for, two or three stages of filtra-
0,01 0,1 1 10 'lm
tion provide advantages with regard to oper- particle size
ating costs. The first filter stage is of a
sturdy structure, and is designed to remove
coarse particles of dust. The high efficiency
filter that follows is designed to remove
fine dust particles. Figure 4 shows the Fig. 5 Particle Surface Distribution in
filtration effect of the two filters as a the Two Stage Filtration System
function of the size of the particles.

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use

 0
2

If all the operating conditions are tion of an air filtration system are dis-
taken into consideration when evaluating cussed below.
various types of filters,the array of para-
meters becomes too large. Several parameters
can be grouped to define typical ambient
conditions to simplify performance compari-
sons. One such grouping is given in Table I. C
In addition to the climatic conditions, '.

specific local conditions, such as wind

direction, local air pollution, elevati-n
of the air inlet above ground level, local
back flows caused by buildings or terrain, C
a,
must be considered. Because of the large
C
number of parameters that effect the opei,. 0
tion of air filtration systems, selection U S D
of the type of filter always entails compro-
mises. V

to
Poole 1 :;ro.nprrw of ;,.,mot•c Con0.tions

Temp Bel Hum Flow of Dust Size Aggressrvity

As oust o
Oiisc Tvpmccl
relative humidity ---
moxlm!n of An dust fine/ of dust. Mater!ol=. Lccotmu
mcx/m rn moe /oon coarse great/small Iergelvmull.
aPm

A 35f-'0 50/90 101001 fine great smolt 000pe.

30/-00 5017 011001 free smelt la-:

Fig. 6 BBC Practice of Filter System
B .. -

I. __
Selection; Recommended Areas of
C 501 0 20/80 much /0l coarse small smell
fine Application
D 50/20 70/90 011001 fine small -rn-I
1. High efficiency filters
2. Roll and mat type filters
Aggressivmty reloimve ccmporson e g cement dust. N 0 1. `- 9 ,- ._ _.,, 3. Pulse and bag filters
Amount of miscellaneous mater / eq insects, fotmoy-rornimonO.,„ .._ 4. Oil bath filters
particles that re00ily adhere 5. Electrostatic filters
6. Inertial separators
7. Wet separators

Table I Grouping of Climatic Conditions Past experience tells us that when there
is fouling of the compressor, the gas turbine
process behaves in a manner similar to when
Figure 6, which conforms to BBC prac- there is an increase in the pressure drop in
tice,demonstrates a method of selecting the air inlet system, i.e., with a loss in
filters for air filtration systems. Two power output of Ap/p = 1 %, the specific
examples are indicated on the figure. Both heat rate Aw/w increases by 0.5 0.
result in the selection of a two stage fil- To justify the use of air filtration,
tration system. Point A has been selected as the additional costs that arise due to the
the initial condition for the first example. installation and maintenance of the filters
According to Fig. 6, an inertial separator should be less than the capitalized losses
can be selected as the first stage filter. due to fouling, erosion and corrosion.
The amount of dust in the inertial separator
will be reduced to Point B. It can be seen It is not yet possible to calculate the
that a dry filter is quite suitable for the losses in power output and efficiency due to
second stage. In the second example, the fouling of the compressor for a given flow
air is relatively moist. The initial condi- and composition of dust. Experience tells us
tion is located at Point C. A wet separator that a large flow of dust, a high humidity,
or an oil-bath filter would enter into con- and a high percentage of fine dust parti-
sideration for the first stage filter. The cles encourage fouling. The measurement of
amount of dust in this filter will be re- dust at the site [2J and operating experience
duced to Point D. An electrostatic filter with regard to losses due to compressor
would be advantageous for the second stage. fouling, figure 7, can be used as an example.
In reference 2, the measured dust flow, on
In addition to selecting the filtration an average, was 0.048 ppm. Assuming a grain
system for optimum operation, consideration size distribution similar to that in figure
must also be given to the customer's specific 4, and filter efficiency of 70 % a dust flow
situation, such as, the availability of of about 0.015 ppm is obtained after the
trained personnel, economic constraints and first filter. The compressor was washed
the planned duty cycle for the gas turbine. about every 5000 hours with practically a
The economic aspects involved in the selec- 100 a recovery in power output. Attempts
were also made to clean the compressor in

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use

 operation using nut-shells with only a planning of a gas turbine plant, the main
20-30 o recovery in losses. The average loss direction of the wind and the location of
in power output over about 15000 hours in those industries that produce dust are to
operation was approximately 6 0, and the be taken into consideration.
thermal efficiency was about 3 % lower than
that for a clean machine. 4. Inertial filters drastically reduce
the danger of erosion due to the coarse
The remaining dust could be removed to particles. In the fine particle range, the
a large extent using a high efficiency second degree of separation is not sufficient to
stage filter. With a dust flow of approxima- prevent fouling of the compressor blading.
tely 0.015 ppm, the life expectancy of such Fouling can be significantly reduced by
a filter is about 10.000 to 12.000 hours. using multistaged filters. Whether such a
Comparison of the investment and maintenance system should actually be built depends on
costs for high efficiency filters with the climatic conditions and on the investment
gain in power output and efficiency makes costs required.
the solution attractive.
5. Since filters reduce the rate of foul-
ing in the compressor, provisions should be
10C made for cleaning the compressor during
operation and during shut down. In most
cases, this solution is optimum from the
point of view of economy.

6. All filters require monitoring and

Tlth/ good maintenance: in the case of oil-bath
fth o
rotating filters, the oil trough must be
P Po cleaned; in the case of oil-coated roll-type
or dry filters, the pads must be replaced;
in the case of pulse filters, the maintenance
of the compressed air unit and possibly re-
placement of the filter elements is required.
If there can be icing or clogging, the fil-
ters have to be provided with a bypass.
90
90 V/vo % 100 7. The costs for maintenance and re-
placement materials vary sharply depending
on the type of filter and the ambient condi-
Fig. 7 Power, Efficiency and Air Volume tions. The removal of coarse and dry dust
Losses as a Result of Compressor is relatively inexpensive. If the dust is
Fouling damp and sticky, additional measures have to
be taken, and these measures make dust remov-
al more expensive. Increasing the degree of
dust removal involves above all filtering
EXPERIENCE - GENERAL
the fine particles of dust. With this, the
expense for materials and maintenance in-
1. Where there is only a small amount of
creases. Costs for separation per kilogram
dust in the air, a number of gas turbines
of dust likewise increases sharply.
and super chargers for Velox boilers have
been operated without filters. That is also
With certain types of filters, the rate
the case for gas turbines that have been
of separation changes during the course of
used as reserve or peak load units. In the
operating time, caused, for example, by
case of several plants, erosion and a fairly
drying of the filter media, by dust im-
severe fouling have been observed. In some
bedding in the filter media, or other
instances, a close-meshed screen had to be
factors.
put in to protect against insects.
The data shown in the suppliers cata-
2. In the case of gas turbines that were
logs are valid generally for new, or only
equipped with air filters, the climatic
slightly clogged filters.
conditions and the quantity and the composi-
tion of the dust have played an important Table II: Relative Filtration Costs
role. The dangers of snow and icing also had
Example.
to be included in the filter concept. Con-
sideration had to be given to the monitoring Separation rote, in % 90 59 999
and the maintenance of the filter unit. Relative costs of separation per kg
of dust, in % 100 400 1500
3. In desert areas where there are sand-
storms, drawing the air from a fairly good
height, about 10 meters, is helpful. In the Table II Relative Filtration Costs

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use

 8. The leakage flows are frequently not
taken into consideration in the data. Depend-

f"
ing on the quality of manufacture and main- 100
tenance, especially when using high effi- r
P
ciency filters it is important to seal all
leaks. 90

9. In order to avoid any interruptions

in service because of filter replacement 80
washing at tow speed _
taken out and replaced, the life expectancy on line cleaning
for the filter elements should be coordina- 100
ted with the overhauls for the plant. Heavi-
ly contaminated roll filters should not be th

moved during operation, because dust will

90
get into the compressor.

10 15
10. Disposal of the used filter pads or
elements, and of the sludge from oil troughs operation time 103h

causes another problem in connection with

protection of the environment.

11. Filter units have to be taken out Fig. 8 Power and efficiency losses as a
and replaced after fairly short time inter- function of time and loss recovery
vals, particularly when they are in a corro- by different methods
sive atmosphere and there is inadequate
maintenance. Good upkeep, e.g., by restora-
tion of painted surfaces and replacement of 3. A gas turbine plant in a desert area
worn parts, is necessary. with frequent sandstorms was equipped with
an inertial separator inlet filter which was
elevated 10 meters above ground level. After
EXPERIENCE - SPECIFIC about 70.000 hours in operation, only very
little erosion was observed on the compressor
1. In BBC-Review February 1979, Pages blades.
97-103 L21, there are reports on the studies
of the air in the environment of a gas 4. A gas turbine for a cement plant in a
turbine plant. The gas turbine was equipped tropical area with a very heavy amount of
with a roll-type filter. In spite of the air airborne dust was initially equipped with
filtration, a loss in power output was meas- roll-type filters and inertial separators.
ured. The use of these filters produced poor re-
sults. Cement dust, together with humidity,
2. BBC Review, December 1980 [11, showed formed a hard crust on both types of filters.
how the losses changed as a function of time, In addition, the roll-type filters clogged
Figure 8. The compressor was cleaned in because of the fine cement dust. Based on
various ways during operation and while at good experience obtained 30 years earlier in
a standstill. Figure 8 also shows the effect the use of oil-bath rotating filters, oil-
of these cleanings. It also illustrates bath rotating filters were installed. Because
that for this plant, dry cleaning in opera- of the very large amount of dust involved,
tion results in only a small recovery of special precautions had to be taken to remove
losses. Washing at very low rotary speeds the oil sludge from the trough. The oil-bath
is very efficient. Installing a last stage rotating filters resolved the filtration
high efficiency filter could be recommended problems.
as an improvement with respect to the foul-
ing of the blades. Because there is a 5. A gas turbine plant on an island, using
danger, of icing, particularly in winter, fuel contaminated with salt water, displayed
preheating of the inlet air also had to be high temperature corrosion on the turbine
employed. blades. In addition to the dust from the
environment, the air also contained salt in
a dry form. Installing high efficiency filters
with coarser pre-filters has produced good
success with respect to the reduction of the
compressor fouling. In addition, the filter
system, in conjunction with a fuel additive,
has successfully reduced the corrosive attack
on the turbine blades. The life expectancy
of the high efficiency filter is 12.000 to
16.000 hours.

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use

 FILTER MEDIA OPERATING DESIGN CONSIDERATIONS :'flNCLUSIONS

1. Inertial separators The dust in the atmosphere causes foul-

When filtering moist, sticky or fibrous ing of the compressor and to a lesser extent,
particles clogging of the turning vanes has a fouling of the turbine as well. Because of
been experienced. When filtering cement dust this, there are losses in power output and
in moist air, a hard coating can form on the efficiency for the plant. The fouling also
vanes. These filters are also susceptible reduces the margin between the operating
to icing. In addition, the scavenging air point and the surge limit. The coarse and
must be ducted away. hard particles of dust erode the blades and
thereby shorten their life expectancy.
2. Oil-bath rotating filters Corrosive materials contained in the dust
These filters are sensitive to uneven flow increase the risk of corrosion to parts in
patterns. The oil must be tailored to the the hot gas path.
type of dust. If the quantity of dust is When selecting a filter, consideration
large, increased sludge removal (by applying should be given to both, the information
centrifuges or settling tanks) is necessary. supplied by the manufacturer of the filter
Oil carry over can also be a problem. The and to operating experience. Economic
filter can ice up. From an environmental aspects should be taken into account by
standpoint the sludge must be properly allowing for investment and maintenance
disposed. costs, by considering how the plant is to
be operated, and by comparing the cost of
3. Oil Coated Roll-Type Filters operation, maintenance and part replacement
Damage has occurred when the rollers were when running with and without inlet air
exposed to high temperatures for an extended filtration.
period of time. Inadequate sealing at the
sides of the mats, drying out of the mats
during long periods at standstill, water ACKNOWLEDGEMENT
retainment and icing are other problems
encountered. The filtering efficiency varies The authors would like to thank all the
with the fouling or drying of the filter people who took active part in the making
media. The used filter rolls have to be dis- of this paper.
carded.

4. Dry Mat Roll-Type Filters REFERENCES

These filters have a low filtering effi-
ciency. Replacing the filter media takes a Ill Zaba, T., "Losses in Gas Turbines
great amount of effort. The pads can hold Due to Deposits on the Blading", Brown Boveri
water and are susceptible to icing. Disposal Review, Vol. 67, December 1980, pp 715-722.
of the dirty filter rolls also must be dealt
with. 12] Felix, P.C. and Strittmatter, W.,
"Analysis Air Pollution on the Erection
5. High Efficiency Filters Site of a Brown Boveri Gas Turbine", Brown
If there is a fairly large amount of dust in Boveri Review, Vol. 66, February 1979,
the air, the filters will have a relatively pp 97-103.
short life. For this reason, these filters
are used with prefilter stages. The filter [3] Romeyke, N. and Stoff, H., "Icing
media can retain water making the filter of Gas Turbine Compressors, and Side Effects
susceptible to icing. The filter elements on Operation", VGB Power Plant Engineering
must be disposed of properly when replaced. 62, Vol. 7, July 1982, pp 552-560.

6. Pulse Filters (Self-Cleaning) [4] Ostrand, Gary G., "Gas Turbine

The filtration system contains a large number Inlet Air Filtration", Sawyer's Turbo-
of elements, such as, filter cartridges, air machinery Maintenance Handbook, First
supply lines and solenoid valves. Poor self- Edition, 1980, Vol. 3, Chapter 10.
cleaning characteristics were experienced
with dust that was moist and sticky. [5] Nordberg, Dennis A., "Air Filters -
Types, Selection and Application", Sawyer's
Gas Turbine Engineering Handbook, Second
Edition, 1972, Vol. 2, Chapter 5.

Downloaded From: https://proceedings.asmedigitalcollection.asme.org on 02/19/2019 Terms of Use: http://www.asme.org/about-asme/terms-of-use