SMANJENJE EMISIJE PRAŠKASTIH MATERIJA POSLE

REKONSTRUKCIJE ELEKTROFILTERSKIH POSTROJENJA NA BLOKU

A6 TE ’’NIKOLA TESLA’’

M. Erić*, Z. Marković

*, P. Škobalj

*, D. Cvetinović

*, P. Stefanović

*,

M.Petković**

, D Stanković**

*Univerzitet u Beogradu, Institut za nuklearne nauke Vinča, P. fah 522, 11001 Beograd, Srbija

**JP EPS PD TENT 11500 Obrenovac, Serbia

Apstrakt: Ratifikovanjem Ugovora o energetskoj zajednici zemalja JI Evrope, Republika Srbija je

2006. godine prihvatila obavezu da do 2017. godine smanji emisiju gasovitih (SOx i NOx) i

praškastih materija u vazduh iz velikih postrojenja (>50 MWth) za sagorevanje fosilnih (čvrstih,

tečnih i gasovitih) goriva u saglasnosti sa zahtevima Evropske Unije tj. prema Direktivi

2001/80/EC. Shodno tome je izvršen prenos evropske regulative u domaće zakonodavstvo: Zakon o

zaštiti vazduha (Sl. Glasnik RS br. 36/09) i Uredba o graničnim vrednostima emisija zagađujućih

materija u vazduhu (Sl. Glasnik RS br. 71/10) a JP Elektroprivreda Srbije je kao društveno

odgovorna firma, već od 2005. godine intenzivno započela sa rekonstrukcijom i modernizacijom

elektrofilterskih postrojenja na svojim blokovima u cilju smanjenja emisije praškastih materija na

dozvoljeni nivo. U PD TENT, posle rekonstukcije elektrofilterskih postrojenja na blokovima TE

Nikola Tesla A: A5 (2004), A1 (2006), A2 (2005) i revitalizovanom bloku A4 (2007), tokom 2010.

godine izvršena je i rekonstrukcija EF na bloku A6 povećane snage (sa 308 MW na 348 MW).

Sredstva za rekonstrukciju EF na bloku A6 povećane snage većim delom su obezbeđena iz

pristupnih fondova EU a manjim delom iz sopstvenih sredstava JP EPS-a. Prema međunarodnom

tenderu i ugovoru izvođač rekonstrukcije EF TENT A6 je bio u obavezi da obezbedi da pri svim

uslovima rada u preostalom radnom veku bloka od 15 godina a naročito pri povećanoj snazi bloka,

obezbedi izlaznu konentraciju praškastih materija ≤ 50 mg/Nm3.

U radu su prikazani rezultati merenja parametara rada kotla/bloka i izlaznih koncentracija praškastih

materija tokom garancijskih ispitivanja rekonstruisanog elektrofilterskog postrojenja koje je kao

nezavisna institucija, prihvaćena od svih zainteresovanih strana iz ugovora, izvršio Institut za

nuklearne nauke Vinča, Laboratorija za termotehniku i energetiku, 2011. godine u saglasnosti sa

standardima ISO 9096 i EN 13284-1.

Ključne reči: praškaste materije, emisija, elektrofilter, rekonstrukcija, modernizacija.

REDUCTION OF PARTICULATE MATTER EMISSION AFTER

ELECTROSTATIC PRECIPITATORS RECONSTRUCTION AT UNIT A6

OF THE TPP “NIKOLA TESLA”

M. Erić*, Z. Marković

*, P. Škobalj

*, D. Cvetinović

*, P. Stefanović

*,

**M.Petković,

**D Stanković

*University of Belgrade, Institute of Nuclear Sciences Vinča, P.O. Box 522, 11001 Belgrade,

Serbia

**JP EPS PD TENT 11500 Obrenovac, Serbia

Abstract: Republic of Serbia as a country signatory (from 2006) of the TREATY establishing

ENERGY COMMUNITY of the SOUTH EASTERN EUROPE (ECSEE) adopted obligations to

reduce emission of SOx, NOx and particulate matter-dust from Large Combustion Plants (>50

MWth) up to 2017. in compliance with EU requirements i.e Directive 2001/80/EC. According to

obligations, transposition of the Directive 2001/80/EC into state legislation have been performed:

Low on air protection (Sl. Glasnik RS br. 36/09) and the Directive on Limitation emission values

for the pollutations emited in air (Sl. Glasnik RS br. 71/10) were addopted by the Parliamanent,

while Electric Power Industry of Serbia (JP EPS) as a socially responsible company have started

with reconstructions and modernization of the electrostatic precipitators on all their units since

2005. TPP Nikola Tesla A performed reconstruction of the electrostatic precipitators at units: A5

(2004), A1 (2006), A2 (2005), A4 (2007) and, at unit A6 with increased power level (from 308,5

MW to 348 MW) during 2010. Most of the investment for the Upgraded Electrostatic Precipitator at

unit A6 were financed by the EU grant while part of the investment was financed by the JP EPS,

too. By the international tender and the Contract, the contractor (RAFAKO) had the obligation to

reconstruct the ESP in that way that the emission of particulate matter should be below 50 mg/Nm3

in all workig conditions of the boiler and ESP, especially under increased power level of the Unit,

during the prolonged life of next 15 years.

Paper presents results of the measurements of boiler/Unit parameters and outlet concentration of

particulate matter during the guarantee investigations for the reconstructed electrostatic precipitators

performed by Institute of Nuclear Sciences Vinča, Laboratory for Thermal Engineering and Energy

as an independent institution, accepted by all parties of the Contract and performed in accordance

with standards ISO 9096 and EN 13284-1.

Key words: particulate matter, emission, electrostatic precipitator, reconstruction, modernization.

1. INTRODUCTION

Republic of Serbia as a country signatory (from 2006) of the TREATY establishing

ENERGY COMMUNITY of the SOUTH EASTERN EUROPE (ECSEE) adopted obligations to

reduce emission of SOx, NOx and particulate matter-dust from Large Combustion Plants (>50

MWth) up to 2017 in compliance with EU requirements i.e Directive 2001/80/EC. PE Electric

Power Industry of Serbia as a socially responsible company has adopted a long-term plan of

modernization for pollution reduction [1]. TPP Nikola Tesla A performed reconstruction of the

electrostatic precipitators at units: A5 (2004), A1 (2006), A2 (2005), A4 (2007) and, at unit A6 with

increased power level (from 308,5 MW to 348 MW) during 2010 to diminish emission of

particulate matter below the referent value of 50 mg/Nm3 [2, 3]. Periodic emission measurements

performed in accordance with standards ISO 9096, have shown that the emission of particulate

matter at unit A6 before reconstruction of electrostatic precipitators, was over referent value (157

mg/Nm3 in 2008

th [1]). With the increase of power level of the Unit A6, emission of particulate

matter after the old ESP should be expected to be further increased due to increased flue gas flow

rate i.e. increased velocity through ESP.

Electrostatic Precipitator System of the unit A6 of Thermal Power Plant ''Nikola Tesla A''

was reconstructed and modernized by Rafako S. A. Poland, in the period from 15.09.2009 to

10.12.2010. Most of the investment for the Upgraded Electrostatic Precipitator at unit A6 were

financed by the EU grant while part of the investment was financed by the JP EPS, too. By the

international tender and the Contract, the contractor (RAFAKO) had the obligation to reconstruct

the ESP in that way that the emission of particulate matter should be below 50 mg/Nm3 in all

workig conditions of the boiler and ESP, especially under increased power level of the Unit, during

the prolonged life of next 15 years.

Test A of upgraded ESP, performed by Institute of Nuclear Sciences „Vinča“, Laboratory

for Thermal Engineering and Energy according to ISO 9096, in period May 25÷27 2011, have

shown that emission of particulate matter is over guarantee value (54 ÷ 131 mg/Nm3), due to

problems with dust removal from the ESP, problems with automated measuring system (AMS) and

ESP working parameters optimization problems [4].

After the correction, improvement and optimization of Electrostatic Precipitator System

working parameters have been done in period June-August 2011 by RAFAKO and TPP Nikola

Tesla, on August 31st and September 1st, performed Control Test: one series of measurements of

dust concentration in the flue gas ducts cross sections before and after ESP in accordance with

standards ISO 9096 and EN 13284-1. During Control Test all measured concentrations at the exit of

Upgraded ESP were much lower than guaranteed value (12 ÷ 28 mg/Nm3) but electrical parameters

of the ESP were at the maximum due to problems with automated measuring system (AMS)

necessary for ESP optimization working mode [5].

After installation of new AMS (Durag 290), its calibration and arrangement of the

optimization working mode of the ESP, repeated guarantee TEST A was performed in period 28÷30

November 2011.

2. BASIC DATA OF UNIT A6

Pulverized coal steam boiler of Unit A6 TPP Nikola Tesla, produced by RAFAKO, Poland

(commissioned in the 1978 year) is of tower type with forced circulation, and nominal unit power

level 308.5 MW. Unit is used as based load (for continuous power generation ~6500 h/year)

according to power demand by Electric Power System of Serbia.

Boiler and the turbine of the unit A6 were upgraded in two phases: in 2008 and 2009/2010.

The reconstruction goals were prolonged life cycle, and increased power level to 350 MW.

Technical parameters of the upgraded steam boiler are presented in table 1.

Table 1. Basic techical characteristic of the upgraded steam boiler for the increased unit power 350 MW

Parameter Unit Value

Nominal HP steam flow t/h 1050

Steam pressure at the boiler outlet Bar 183

HP steam temperature °C 543

Nominal flow of reheated steam t/h -

Steam pressure at RH1 inlet Bar -

Temperature of reheated steam °C 543

Thermal Power Plant ”Nikola Tesla A” is burning lignite supplied from open pit mines Kolubara

coal basin, with a wide range of quality. Typical range of Kolubara lignite quality characteristics

and Guarantee values for the Upgraded Electrostatic Precipitator System operation are presented in

table 2.

The flue gas design parameters at the inlet of the ESP for the guarantees of the Upgraded ESP are

presented in the table 3.

Table 2 Range of Kolubara lignite quality and Guarantee values for the Upgraded ESP

Unit Range Guarantee value

Lower Calorific Value kJ/kg 5860÷7300 6700

Ash % 22% (±3%) 20% (±2%)

Combustible % 32 (±3%) 30

Moisture % 45 ÷ 53 48

Sulphur % 0.52 0.52

Table 3 Basic design flue gas parameters at the inlet of the upgraded ESP TENT A6

Parameter Unit Value

Load MW 350

Flue gas volumetric flow rate through two ESPs,

burning reference lignite (0 ºC, 1013 mbar, dry) Nm

3/h 1,800,000

Flue gas temperature °C 170

Flue gas Under Pressure Pa 3189

O2 content in the flue gas mixture % 6.0

CO2 content in the flue gas mixture % 12.5

H2O content in the flue gas mixture % 20

Dust concentration in flue gas upstream the ESPs (0

ºC, 1013 mbar, dry, O2=6%) g/Nm

3 52

Pressure drop across ESP Pa 250

Temperature drop across ESP K 10

The Electrostatic Precipitators (ESP) at the exit of boiler Unit A6 were produced and

installed in 1978 by ELWO, Poland. Upgraded (reconstructed and modernized) Electrostatic

Precipitator System by RAFAKO, Poland, is shown on Figure 1. Basic technical characteristics of

the upgraded Electrostatic Precipitators System are presented in table 4.

Modernization of Electrostatic Precipitator System at unit A6, TPP ’’Nikola Tesla’’

included following improvements: spacing between electrodes is increased from 300 mm to 395

mm, and the length of electrodes is increased Discharge Electrode rapping system is displaced over

above electrodes which enabled extending of each active field for up to 4.5 m, too. The height of

the existing ESP chamber is raised by 8350 mm during reconstruction.

Upgraded ESP has 16 independent electrical fields arranged in 4 parallel series (two in the

left ESP chamber and two in the right ESP chamber). Each series has 3 collection zones; the first

zone is electrically divided in two independent fields so that both left/right chamber of the ESP have

8 HV T/R Units, in total 16 for whole ESP.

Due to increased height of the ESP chamber, completely new flue gas ducts with shut-off

dumpers (of the louvers type) and expansion joints as well new inlet hoods and outlet hoods were

installed. Exit flue gas ducts are refurbished and upgraded. The flue gas ducts and hoods are

equipped with new gas distribution devices to improve flue gas distribution i.e. to obtain uniform

flue gas distribution profile and to decrease the erosive effect of the dust particles.

Figure 1. Photo of the left part of the upgraded ESP - side view

Table 4 Basic techical characteristic of the upgraded ESP after reconstruction

Characteristic Unit Value

Effective field high M 16,00

Effective field length M (2,5+2,0 +2 x 4,5)

Number of gas passages 2x50

Gas passages spacing Mm 395

Collecting surface m2

2x21600

Flue gas forward flow velocity m/s 1,61

treatment time S 8,4

Outlet flow control baffling Yes, screen plates

Discharge electrode / Collecting electrode Tube with spikes / SIGMA VI

Collection zone

Electric field

Zone I

Field 1

Zone I

Field 2

Zone II

Field 3

Zone III

Field 4

Max continuous voltage at the electrode kV 106

Max continuous current at the electrode mA 800 800 1400 1400

Max continuous power kVA 85 85 148 148

Hopper slope angle in corner valley. Deg 30

Capacity of hoppers to the Height Level

Alarm m

3 38

3. TEST RESULTS

Repeated guarantee test A of the Electrostatic Precipitator System (ESP) of the unit A6 of

Thermal Power Plant ''Nikola Tesla '' was performed by Institute of Nuclear Sciences „Vinča“,

Laboratory for Thermal Engineering and Energy according to ISO 9096 in the period 28÷30

November 2011.

Three tests have been performed at approximately 100 % nominal unit power for both

precipitators at the same time. Totally, six tests have been performed. Test results of particulate

matter emission for both electrostatic precipitators at unit A6 are shown in Table 5 and Figures 2÷5

[6].

Electrostatic precipitators manufacturer guarantees that emission of particulate matter is

under guarantee value 50 mg/Nm3 (dry gas, O2=6%), only if gases are dedusting from electrostatic

precipitator under conditions with parameters which are shown in Tables 1÷3.

Table 5 Results of the ESP Guarantee test A at unit A6 of TPP ''Nikola Tesla''

Parameter

Test 1

Left

ESP

Test 1

Right

ESP

Test 2

Left

ESP

Test 2

Right

ESP

Test 3

Left

ESP

Test 3

Right

ESP

Averaged

value for 3

series

Power level [MW] 348 347 346 347

Coal/Low calorific

value [MJ/kg] 7560 7701 7496 7586

Coal/Moister content

[%] 47.8 47.6 47.8 47.7

Coal/Ash Content [%] 18.3 17.3 17.9 17.8

Particulate matter

emission [mg/Nm3]

69.5 53.8 13.7 16.9 32.6 16.6 33.85

Electrostatic

precipitator efficiency

[%]

99.86 99.90 99.97 99.97 99.94 99.97 99.935

Particulate matter

emission [kg/h] 49.8 36.1 10.0 11.5 23.0 10.9 23.55

Particulate matter

emission [mg/MWh] 0.143 0.104 0.029 0.033 0.066 0.032 0.068

During the Test 1 the electric working parameters of the UESP were relatively low (<60%)

due to low “setup” value of the factor correlating signal from the Automated measuring system

(AMS) with electric parameters of the UESP in the optimization working mode and as a result

particulate matter emission were (69.5 mg/Nm3 at the left ESP and 53.8 mg/Nm

3 at the right ESP)

higher than guaranteed value. After the correction of “setup” value of this factor in the Test no 2

and 3, electric working parameters of the UESP were increased and the measured particulate matter

emission was much lower than guaranteed value.

Avaraged mean particulate concentration at the exit of Upgraded ESP for the perfomed 3

tests during Guarantee Test A was 33.85 mg/Nm3 i.e. it was below gurantee value (50 mg/Nm

3).

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

Limit value

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

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

Pa

rti

cu

late

ma

tter e

mis

sio

n [

mg

/Nm

3]

Av

era

ged

valu

e f

or

3 s

eri

es

Figure 2. Particulate matter emission test results of ESP at unit A6

99.80

99.82

99.84

99.86

99.88

99.90

99.92

99.94

99.96

99.98

100.00

Guaranteed value

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

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

Ele

ctr

ost

ati

c p

recip

ita

tor e

ffic

ien

cy

[%

]

Av

era

ged

va

lue f

or 3

serie

s

Figure 3. Electrostatic percipitator effiency at unit A6

0

5

10

15

20

25

30

35

40

45

50

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

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

Pa

rti

cu

late

ma

tter e

mis

sio

n [

kg

/h]

Av

era

ged

va

lue f

or 3

serie

s

Figure 4. Particulate matter emission test results in kg/h at unit A6

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

0.14

0.15

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

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

Pa

rti

cu

late

ma

tter e

mis

sio

n [

kg

/MW

h]

Av

era

ged

va

lue f

or 3

serie

s

Figure 5. Particulate matter emission test results in kg/MWh at unit A6

According to the Contract Additional Guarantee Test of the Electrostatic Precipitator System

at Unit A6 TPP “Nikola Tesla A” was performed to simulate the case when one T/R is off, when

emission of particulate matter should be below 100 mg/Nm3. This additional Test no. 4 was

performed on November 30, 2011 with one T/R off. Based on simultaneous measurements of the

particulate matter emission in the exit cross section of the left and the right part of the UESP, the

average value of mean particulate concentration in the test no 4 was 16.9 mg/Nm3, much more

below gurantee value (100 mg/Nm3).

4. CONCLUSION

After initial working period, necessary for the correction, improvement and optimization of

the Upgraded Electrostatic Precipitator System TENT A6 working parameters (done by RAFAKO

and TENT), Institute of Nuclear Sciences, Laboratory for Thermal Engineering and Energy

performed (in period 28÷30 November 2011), particulate emission Guarantee Test A in the flue gas

ducts cross sections after ESP in accordance with standards ISO 9096.

Obtained results of Guarantee Test A of the Upgraded Electrostatic Precipitator System at

Unit A6 TPP “Nikola Tesla A” was:

average particulate matter emission value of the UESP for Test No.1 = 61.65 mg/Nm3,

average particulate matter emission value of the UESP for Test No.2 = 15.3 mg/Nm3,

average particulate matter emission value of the UESP for Test No.3 = 24.6 mg/Nm3,

During the Test 1 the electric working parameters of the UESP were relatively low (<60%)

due to low “setup” value of the factor correlating signal from the Automated measuring system

(AMS) with electric parameters of the UESP in the optimization working mode and as a result

particulate matter emission were higher than guaranteed value (69.5 mg/Nm3 at the left ESP and

53.8 mg/Nm3 at the right ESP). After the correction of “setup” value of this factor in the Test no 2

and 3, electric working parameters of the UESP were increased and the measured particulate matter

emission was much lower than guaranteed value.

Avaraged mean particulate concentration at the exit of Upgraded ESP for the perfomed 3

tests during Guarantee Test A was 33.85 mg/Nm3 i.e. it was below gurantee value (50 mg/Nm

3).

Additional Guarantee Test of the Electrostatic Precipitator System at Unit A6 TPP “Nikola

Tesla A” was performed to simulate the case when one T/R is off, when emission of particulate

matter should be below 100 mg/Nm3. Simultaneous measurements of the particulate matter

emission in the exit cross section of the left and the right part of the UESP during additional Test

no. 4 with one T/R off, have shown that the average value of mean measured particulate

concentration, was 16.9 mg/Nm3, much more below gurantee value (100 mg/Nm

3).

ACKNOLIGMENT

This work as a part of the Project III 42010 “Reduction of Air Pollution from Thermal Power Plants

of the PE ELECTRIC POWER INDUSTRY OF SERBIA” was financially supported by Ministry of

Education, Science and Technological Development of the Republic of Serbia.

REFERENCES

[1] Gavrić, M., Vlajčić, A., Čeperković, B.: Green Book of the Electric Power Industry of Serbia,

Belgrade 2009, www.eps.rs

[2] Erić, M., Stefanović, P., Kisić, D.: Reduction Verification of the Particulate Matter Emission

after Electrostatic Precipitators Reconstruction at Units A1, A2 and A4 of the TPP Nikola Tesla,

TERMOTEHNIKA, 2010, XXXVI, 1, 173-180.

[3] Kisić, D., Žbogar Z., Milić, M., Ćeran, N., Strugar, G., Stefanović, P., Erić, M.: Reduction of

Particulate Matter Emission after Electrostatic Precipitators Reconstruction at the TPP Nikola

Tesla A, Proceedins, International Symposium Power Plants 2008, Vrnjačka Banja, 2008.

[4] Stefanović, P., Erić, M., Erić, A., Spasojević, V., Škobalj, P.: Particulate Emission Test A of

The Upgraded ESP at Unit A6 Of TPP “Nikola Tesla” Obrenovac, Report NIV LTE 479,

Institute of Nuclear Sciences Vinča, Vinča, 2011.

[5] Stefanović, P., Erić, M., et all: Particulate Emission Control Test of the Upgraded ESP at Unit

A6 Of TPP “Nikola Tesla” Obrenovac, Report NIV LTE 486, Institute of Nuclear Sciences

Vinča, Vinča, 2011.

[6] Stefanović, P., Erić, M., et all: Particulate Emission Guarantee Test A of the Upgraded ESP at

Unit A6 Of TPP “Nikola Tesla” Obrenovac, Report NIV LTE 490, Institute of Nuclear Sciences

Vinča, Vinča, 2011.