ispitivanje radnih uslova ventilatora hladnih dimnih...

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.

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

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.

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


(pressure 101325 Pa, Temperature 273 K, dry gas) O2=6% mg/Nm

3 2884.6 / 2148.2

TEST No.2

Load MW 270




measured O2

mg/Nm3 7414.9 / 1513.2

*



3 8490.4 / 1598.5

*

TEST No.3

Load MW 285




measured O2

mg/Nm3 2717.7 / 2015.7



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.

0

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Guaranteed value

Test number (L-left ESP / R-right ESP)

1L 1R 2L 2L 3L 3R

Pa

rti

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late

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tter e

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mg

/Nm

3]

Av

erag

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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].

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

Lin

(C

ou

nts

)

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2-Theta - Scale

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

Lin

(C

ou

nts

)

0

100

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400

500

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1200

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1400

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1700

2-Theta - Scale

10 20 30 40 50 60 70 80 90

Figure 4. XRD method test results of particulate matter composition for sample 2

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

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:



Test No.3:



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.

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.

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