ISPITIVANJE RADNIH USLOVA VENTILATORA HLADNIH DIMNIH...
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ISPITIVANJE RADNIH USLOVA VENTILATORA HLADNIH DIMNIH
GASOVA KOTLA TE ''UGLJEVIK''
M. Erić, Z. Marković, P. Škobalj, D. Cvetinović, V. Spasojević, P. Stefanović
Univerzitet u Beogradu, Institut za nuklearne nauke Vinča, P. fah 522, 11001 Beograd, Srbija
Apstrakt: Blok ''Ugljevik'' I je u pogonu od 1985 godine kada je blok pušten u rad. Postojeće
elektrofiltersko postrojenje u TE ''Ugljevik'' je projektovano za efikasnost otprašivanja od 99,68 %.
Pri nominalnom radu od 300 MW, elektrofilteri izdvajaju oko 110 t/h pepela. Projektovana
koncentracija ukupnih praškastih materija u dimnom gasu na izlazu iz elektrofiltera je 150 mg/Nm3,
što je danas znatno pogoršano u odnosu na početni period.
U uslovima povećane koncentracije čestica letećeg pepela radni vek ventilatora hladnih dimnih
gasova je znatno snižen usled abrazije lopatica radnog kola. Zbog toga je ugrađena konstrukcija
vetilatora hladnih dimnih gasova koja može da radi u radnim uslovima povećane koncentracije
praškastih materija do 2000 mg/Nm3. Novi ventilatori su pohabani pre predviđenog broja radnih
sati.
Proizvođač opreme je angažovao Institut za nuklearne nauke ’’Vinča’’, Laboratoriju za
termotehniku i energetiku. da izvrši ispitivanja koncentracije praškastih materija u dimnom kanalu
na izlazu iz elektrofiltera, a pre mesta izdvajanja hladnih dimnih gasova. Pored zahtevanih
ispitivanja Institut za nuklearne nauke ’’Vinča’’ je izvršio i dodatna ispitivanja.
U radu će biti prikazani rezultati merenja koncentracija praškastih materija, sadržaja SO2 u dimnom
gasu i ispitivanja sastava kristalnih jedinjenja u uzorcima letećeg pepela.
Ključne reči: koncentracija praškastih materija, ventilator hladnih dimnih gasova, kristalna
jedinjenja, Rendgenska strukturna analiza.
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INVESTIGATION ON WORKING CONDITIONS OF COLD FLUE GASES
FANS AT STEAM BOILER OF THE TPP “UGLJEVIK”
M. Erić, Z. Marković, P. Škobalj, D. Cvetinović, V. Spasojević, P. Stefanović
University of Belgrade, Institute of Nuclear Sciences Vinca, P.O. Box 522, 11001 Belgrade,
Serbia
Abstract: The unit ''Ugljevik'' I has been in operation since 1985, when the unit put into operation.
Existing electrostatic precipitators in TPP ''Ugljevik'' are designed for dust removal efficiency of
99.68%, At the nominal operation of 300 MW electrostatic precipitators separate about 110 t/h of
flying ash. Total designed concentration of particulate matter in the flue gas at the outlet of the
electrostatic precipitator 150 mg/Nm3. Today concentration is significantly higher than in earliar
period.
In conditions of increased concentration of particulate matter lifetime of cold flue gases fan is
significantly reduced due to the abrasion of turbine blades. Therefore, the new design of cold flue
gases fans are mounted, which can work in the working conditions of increased concentrations of
particulate matter up to 2000 mg/Nm3. New fans are worn before the scheduled hours of work.
Institute of Nuclear Sciences ''Vinca'', Laboratory for Thermal Engineering and Energy was
engaged by equipment manufacturer to perform tests of dust concentration in the flue channel at the
outlet of electrostatic and before segregation of cold gases. In addition to the required tests for the
Institute of Nuclear Sciences ''Vinca'' was conducted additional tests .
The paper presents the results of the following tests: measurement of particulate matter
concentration and the SO2 content in the flue gas and tests of the composition of crystalline
compounds in samples of fly ash.
Key words: particulate matter concentration, cold flue gases fan, crystalline compounds, X-ray
difraction analysis.
1. INTRODUCTION
Thermal Power Plant has been in operation since 1985. During the war in Bosnia and Herzegovina
from 1992 to 1995 year thermal power plant was out of order. Installed capacity of the thermal
power plant Ugljevik I is 300 MW, with 1601 GWh of electrical energy per year. The unit Ugljevik
I has been projected to work 200.000h. The unit has been working 104.500 h or 52% of projected
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lifetime. Thermal power plant is using coal from open pit mine "Bogutovo Selo". Electrostatic
precipitator (Figure 1) has been in operation since 1985 [1-2].
In the conditions of increased concentration of particulate matter at the outlet of electrostatic
precipitator there is problem of abrasion fan blades of cold flue gasses. Because of mentioned
above, new construction of cold flue gasses fan has been installed, which can operate up to
concentration level of 2000 mg/Nm3 of particulate matter. New fans are worn before the scheduled
hours of work.
Figure 1. Electrostatic precipitator and cold flue gas fan at left side of the steam boiler
Manufacturer of equipment engaged Institute of Nuclear Sciences Vinca, Laboratory for thermal
engineering in order to determine work conditions of cold flue gases fans, to perform tests of
particulate matter concentration in dust channel at the end of electrostatic precipitator and before
segregation of flue gasses. Institute of Nuclear Sciences of Vinca has done additional examination
which can explain problems of turbine blades abrasion: determination of SO2 content in flue gas
and determination of flying ash composition by X-ray difraction method.
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2. TEST METHODS AND RESULTS
Particulate matter test of the Electrostatic Precipitator System (ESP) of the unit ''Ugljevik I'' was
performed by Institute of Nuclear Sciences „Vinča“, Laboratory for Thermal Engineering and
Energy according to ISO 9096. Special filters for high level particulate matter concentrations were
used because expected concentration was much higher than standard range from 20 mg/Nm3 to
1000 mg/Nm3. Measuring plane was defined behind electrostatic precipitator and before the
segregation of flue gas for cooling the hot recirculated flue gases.
Three tests were performed during the two days at both ESPs, which results are shown in the Table
1 and Figure 2 [1].
Table 1. Test results of particulate matter content in the flue gas behind ESP
Parameter Unit Value - Left / Right ESP
TEST No.1
Load MW 270
Content O2 in the flue gas % 7.90 / 6.80
Particulate matter content in the flue gas at ESP exit
(pressure 101325 Pa, Temperature 273 K, dry gas)
measured O2
mg/Nm3 2591.2 / 2033.7
Particulate matter content in the flue gas at ESP exit
(pressure 101325 Pa, Temperature 273 K, dry gas) O2=6% mg/Nm
3 2884.6 / 2148.2
TEST No.2
Load MW 270
Content O2 in the flue gas % 7.90 / 6.80
Particulate matter content in the flue gas at ESP exit
(pressure 101325 Pa, Temperature 273 K, dry gas)
measured O2
mg/Nm3 7414.9 / 1513.2
*
Particulate matter content in the flue gas at ESP exit
(pressure 101325 Pa, Temperature 273 K, dry gas) O2=6% mg/Nm
3 8490.4 / 1598.5
*
TEST No.3
Load MW 285
Content O2 in the flue gas % 6.82 / 6.38
Particulate matter content in the flue gas at ESP exit
(pressure 101325 Pa, Temperature 273 K, dry gas)
measured O2
mg/Nm3 2717.7 / 2015.7
Particulate matter content in the flue gas at ESP exit
(pressure 101325 Pa, Temperature 273 K, dry gas) O2=6% mg/Nm
3 2874.9 / 2068.1
* Results of test No. 2 are not considered because of ESP operating mode has been significantly changed during the
sampling
Sulfur dioxide content in the flue gas are measured during particulate matter sampling for all three
tests in accordance with standard ISO 7935. Measurements were performed with Fuji ZKJ3 gas
analyzer by NDIR method. Measuring range of the instrument is from 0 to 14285 mg/Nm3. The
measured SO2 content was much higher than range of instrument for all three tests.
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Figure 2. Test results of particulate matter concentration at the exit of ESP
Flying ash composition analysis was determined by X-ray difraction method (XRD method). X-ray
difraction has long been used as a definitive technique for identification of crystalline mineral
components, and represents the most suitable method for identifaying minerals and other crystalline
phases in a wide range of natural and syntetic materials. XRD is reliably method, especially in
materials such as fly ash, where the individual crystals can not be identified by other techniques.
The X-ray diffraction pattern of a pure substance is, therefore, like a fingerprint of the substance.
The powder diffraction method is thus ideally suited for characterization and identification of
polycrystalline phases.
Today about 50,000 inorganic and 25,000 organic single component, crystalline phases, diffraction
patterns have been collected and stored on magnetic or optical media as standards. The main use of
powder diffraction is to identify components in a sample by a search/match procedure. Furthermore,
the areas under the peak are related to the amount of each phase present in the sample [3-4].
Two samples flying ash are sampled at the same measuring plane which was used for particulate
matter concentration sampling. XRD analyses results of two collected samples are given in Figures
3 – 5 [1].
The Mohs scale of hardness (Figure 6) is the most common method used to rank minerals according
to hardness. This scale grades minerals on a scale from 1 (very soft) to 10 (very hard). Mohs scale is
a relative scale, the difference between the hardness of a diamond and that of a ruby is much greater
than the difference in hardness between calcite and gypsum. As an example, diamond (10) is about
4-5 times harder than corundum (9), which is about 2 times harder than topaz (8) [5].
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TE Ugljevik Fly Ash 08.07.2011
01-071-2014 (C) - Iron Sulfate - FeSO3 - S-Q 2.1 %
01-071-1378 (C) - Iron Sulfate - Fe2(SO4)3 - S-Q 2.2 %
01-072-0916 (C) - Anhydrite - Ca(SO4) - S-Q 27.0 %
01-079-1345 (C) - Dolomite - CaMg(CO3)2 - S-Q 16.1 %
01-089-3072 (C) - Corundum, syn - Al2O3 - S-Q 21.1 %
03-065-0466 (C) - Quartz low, syn - SiO2 - S-Q 11.1 %
01-089-8103 (C) - Hematite, syn - Fe2O3 - S-Q 8.1 %
01-074-1226 (C) - Lime - CaO - S-Q 10.5 %
01-089-5957 (C) - Potassium Peroxide - KO2 - S-Q 1.8 %
Operations: Range Op. B-A | Bezier Background 1.000,1.000 | Import
UZORAK1 - File: UZORAK1.raw - Type: 2Th/Th locked - Start: 10.000 ° - End: 90.000 ° - Step: 0.050 ° - Ste
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10 20 30 40 50 60 70 80 90
Figure 3. XRD method test results of particulate matter composition for sample 1
TE Ugljevik Fly Ash 09.07.2011
01-071-2014 (C) - Iron Sulfate - FeSO3 - S-Q 1.5 %
01-071-1378 (C) - Iron Sulfate - Fe2(SO4)3 - S-Q 1.5 %
01-072-0916 (C) - Anhydrite - Ca(SO4) - S-Q 30.2 %
01-079-1345 (C) - Dolomite - CaMg(CO3)2 - S-Q 15.3 %
01-089-3072 (C) - Corundum, syn - Al2O3 - S-Q 20.4 %
03-065-0466 (C) - Quartz low, syn - SiO2 - S-Q 11.4 %
01-089-8103 (C) - Hematite, syn - Fe2O3 - S-Q 6.8 %
01-074-1226 (C) - Lime - CaO - S-Q 10.9 %
01-089-5957 (C) - Potassium Peroxide - KO2 - S-Q 2.0 %
Operations: Range Op. B-A | Bezier Background 1.000,1.000 | Import
UZORAK2 - File: UZORAK2.raw - Type: 2Th/Th locked - Start: 10.000 ° - End: 90.000 ° - Step: 0.050 ° - Ste
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10 20 30 40 50 60 70 80 90
Figure 4. XRD method test results of particulate matter composition for sample 2
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No. Mineral Unit Sample I Sample II
1. Potassium peroxide – KO2 % 1,8 2,0
2. Lime – CaO % 10,5 10,9
3. Hematite – Fe2O3 % 8,1 6,8
4. Quartz – SiO2 % 11,1 11,4
5. Corundum – Al2O3 % 21,1 20,4
6. Dolomite – CaMg(CO3)2 % 16,1 15,3
7. Anhidrite (Калцијум сулфат) – Ca(SO4) % 27,0 30,2
8. Iron sulfate - Fe2(SO4) % 2,2 1,5
9. Iron sulfate – FeSO3 % 2,1 1,5
Figure 5. XRD method test results of particulate matter composition, sampled in the flue gas behind ESP
Three hard minerals, which have major contributin on abrasion of cold flue gases fan blades, were
found in analysed samples: Corundum (~ 21%, Mohs scale 9), Quartz (~ 11%, Mohs scale 7) and
Dolomite (~ 8%, Mohs scale 5.5).
Figure 6. Mohs Mineral Hardnes scale
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3. CONCLUSION
The extremely high concentrations of particulate matter were measured at the outlet of electrostatic
precipitators:
Test No.1:
- average value for left ESP 2884,6 mg/Nm3
- average value for right ESP 2148,2 mg/Nm3
Test No.2:
- average value for left ESP 8490,4 mg/Nm3
- average value for right ESP 1598,5 mg/Nm3
Test No.3:
- average value for left ESP 2874,9 mg/Nm3
- average value for right ESP 2068,1 mg/Nm3
that are over 40 times higher than the emission limit values for plants with thermal capacity of over
500 MW (50 mg/Nm3) and significantly lead to damage to devices and flue channels.
Operation conditions during the Test No. 2 were not regular because of ESP operating mode has
been significantly changed, and the results were not taken into consideration.
Very high content of SO2 was measured in the flue gases (> 14 285 mg/Nm3) that, in low
temperature zones, with no intense flows, reacts with a condensate and create sulfurous acid which
causes corrosion of materials.
X-ray difraction has shown great content of hardest minerals that contribute most to the abrasion of
material:
Corundum – Al2O3 (~ 21%, Mohs Mineral Hardness scale 9),
Quartz – SiO2 (~ 11%, Mohs Mineral Hardness scale 7) и
Hematite – Fe2O3 (~ 8%, Mohs Mineral Hardness scale 5.5),
that in the total sum account for approximately 40% of the total amount of particulate matter which
passes through the electrostatic precipitator.
Modernization and reconstruction of electrostatic precipitators and installation system of
desulphurization processes can increase the service life of thermal power plants and eliminate above
mentioned problems.
ACKNOLIGMENT
This work as a part of the Project III 42010 was financially supported by Ministry of Education,
Science and Technological Development of the Republic of Serbia.
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REFERENCES
[1] Erić, M., Radovanović, P., Working Conditions of Cold Flue Gases Fans at Steam Boiler of the
TPP “Ugljevik” in Ugljevik, Report NIV LTE 481, Institute of Nuclear Sciences Vinča, Vinča,
2011.
[2] Grubor, B., Repić, B., Stefanović, P., Investigation on Electrostatic Precipitators Efficiency of
the TPP “Ugljevik” , Report NIV LTE 172, Institute of Nuclear Sciences Vinča, Vinča, 2000.
[3] Colin, W., D., Relation Between Coal and Fly Ash Mineralogy, Based on Quantitive X-Ray
Diffraction Methods, 2005 World of Coal Ash (WOCA), April 11-15, 2005., Lexington,
Kentacky, USA.
[4] Colin, W., (School of Biological, Eart and Enviromental Sciences), Characteristic of Australian
Fly Ashes Based on Quantitive X-Ray Diffraction Analysis, Cooperative Research Centre for
Coal in Sustainble Development December 2003, Technical Note 21
[5] Schuman, W., Minerals of the World, Sterling Publishing Co. Inc., New York, 2008.