1. Reducing Mercury Emission from Coal Combustion
in the Energy Sector in Thailand
Presented by
Faculty of Public Health, Thammasat University
November 7, 2017

2. Topics I. Introduction II. Coal information
III. Coal-fired power plant information
IV. Coal sampling and analysis
V. Future mercury emission estimation

3. I. Introduction

4. I. Mercury Cycle
Source:

5. I. How do Coal-Fired Plant Work?
Coal Supply
Conveyer
Pulveriser /Mill
Boiler
Ash Systems
Water Purification
Stack
Condenser
Substation/ Transformer
Generator
Steam turbine
Electricity
Source:

6. II. Coal Information

7. II. Coal information : Type of coal and its utilization in Thailand
Lignite
Bituminous
Sub-bituminous
Anthracite
Lignite is the most common coal produced in Thailand. It is commonly used for electricity generation, but not widely used in industry because it contains lower energy and higher pollution comparing with other coal types.
Anthracite, bituminous, and sub-bituminous which are used in industrial processes and electricity generation are mainly imported from Indonesia and Australia (Thai Custom Department, 2017).

8. II. Coal information : Coal consumption in Thailand
In 2016, coal and lignite are consumed around 38,457,405 tons, with 64% for electricity, and the rest for industry. Most of domestic lignite (97%) was used in electricity generation, whereas imported coal (60%) was mainly used in industrial processes.
Industry
Electricity
The share of coal consumption for electricity generation was significantly increased to 35% in 2016, lignite is still the main material for Thai coal power plant (around 65%).
The amount of lignite used in coal-fired power plant is stable within around 16,000,000 to 18,000,000 tons per year during the last decades.

9. III. Coal Fired Power Plant Information

10. III. Coal fired power plant
: Situation of electricity generation in Thailand
Main electricity producers are the EGAT (Electricity Generating Authority of Thailand), the IPPs (Independent Power Producers), the Small Power Producers (SPPs) and the Very Small Power Producers (VSPPs).
Total capacity of the existing coal-fired power plants in Thailand with the rate of 8,704 MW.
The two largest power plants operated in the country belong to the Mae Moh power plant and the BCLP power plant with the total installed capacities of 2,180 and 1,434 MW, respectively.
Electricity production capacity sorted by Producer

11. III. Coal fired power plant
: National and Provincial Air Pollution Control and Operational Efficiency
List
Air Pollutants
NOx
SO2 PM
APC Technology
Low NOx Burner (LNB),
Over Fired Air (OFA)
Selective Catalytic Reduction (SCR)
Flue Gas Desulfurization (FGD) using Limestone or Seawater
Electro Static Precipitator (ESP)
Bag Filter
Operational efficiency
63.6%-95.0%.
77.5%-97.0%
99.3%-99.9%.

12. IV. Coal Sampling and Analysis

13. Oxygen Bomb Combustion/ Ion Chromatographic Method
IV. Coal sampling
: Analysis Methods for Coal Sample
Parameter
Analysis Method
1) Proximate Analysis
Total Moisture
ASTM D3302/D3302M-12
Inherent Moisture
ASTM D
Volatile Matter
Fixed Carbon
Ash
2) Ultimate Analysis
Carbon(C)
ASTM D
Hydrogen(H)
Nitrogen(N)
Sulfur(S)
ASTM D
Oxygen(O)
Calculation
Parameter
Analysis Method
3) Chemical Composition
Mercury (Hg)
ASTM D
Arsenic (As)
ASTM D
Selenium (Se)
Sodium (Na)
Calcium (Ca)
Barium (Ba)
Chlorine (Cl)
ASTM D
Bromine (Br)
Oxygen Bomb Combustion/ Ion Chromatographic Method

14. IV. Coal sampling
: Analysis Methods for mercury in coal and coal combustion product
Substance
Analysis Method
Pulverized coal
ASTM D
Bottom ash
Fly ash
Limestone and gypsum
U.S.EPA 1631
Stack emission
U.S. EPA Method 29

15. IV. Coal sampling : Summary of coal samples Code: Plant/Source
The ASTM D procedure (Standard Practice for Collection of Channel Samples of Coal in a Mine) were modified for coal sampling in this study.
Code: Plant/Source
Type of coal
Number of sample
Plant 1 (source 1)
BC: (Bee Creek), Australia
HV: (Hunter Valley), Australia
SU: (Suek), Russia
Bituminous
15 samples 5
Plant 2 (source 2)
CS1: (Lignite mine: Spec 1), Thailand
CS2: (Lignite mine: Spec 2), Thailand
Lignite
10 samples

16. III. Coal sampling : Summary of coal samples Code: Plant/Source
Type of coal
Number of sample
Plant 3 (source 3)
JM: SM 300 (PT Jembayan muarabara), Indonesia
KP: SM 301 (PT Kaltim Pruma coal) ), Indonesia
KM: SM 302 (PT Khotia Makmur insan Abidi), Indonesia
Bituminous
15 samples 5
Plant 4 (source 4)
BP: (Indominco), Indonesia
LH: (Lanna Harita), Indonesia
10 samples
Total 50

17. III. Results of Coal analysis
Blue bars: Coal source 1
Red bars: Coal source 2
Green bars: Coal source 3
Yellow bars: Coal source 4
III. Results of Coal analysis
: Properties of coal samples
Proximate analysis of feed coals (Unit: %)
Percentage (%)

18. III. Results of Coal analysis
Blue bars: Coal source 1
Red bars: Coal source 2
Green bars: Coal source 3
Yellow bars: Coal source 4
III. Results of Coal analysis
: Properties of coal samples
Ultimate analysis of feed coals (Unit: %)
Percentage (%)

19. III. Results of Coal analysis
Blue bars: Coal source 1
Red bars: Coal source 2
Green bars: Coal source 3
Yellow bars: Coal source 4
III. Results of Coal analysis
: Properties of coal samples
Chemical analysis of feed coals
Unit: mg/kg
Unit: g/kg
ND < 1.00

20. III. Results of Coal analysis
Blue bars: Coal source 1
Red bars: Coal source 2
Green bars: Coal source 3
Yellow bars: Coal source 4
III. Results of Coal analysis
: Properties of coal samples
Chemical analysis of feed coals
Unit: mg/kg
Unit: μg/kg

21. III. Results of Coal analysis
Blue bars: Coal source 1
Red bars: Coal source 2
Green bars: Coal source 3
Yellow bars: Coal source 4
III. Results of Coal analysis
: Properties of coal samples
Chemical analysis of feed coals
Unit: g/kg
Unit: μg/kg

22. III. Results of Coal analysis
Blue bars: Coal source 1
Red bars: Coal source 2
Green bars: Coal source 3
Yellow bars: Coal source 4
III. Results of Coal analysis
: Properties of coal samples
Chemical analysis of feed coals
Unit: g/kg
Unit: g/kg

23. III. Results of Mercury analysis
: Mercury concentration and speciation in coal fired power plant
Mercury was sampled from two power plants (four units) in Thailand and there are six types of sample to be collected at each power plant as follows:
Sample types
Sampling points
Pulverized coal
Bottom ash
Fly ash
Seawater
Lime and Gypsum
Stack gas 1 2 3 4 5 6
PC boiler
ESP
FGD
Bottom ash
Fly-ash
Sea water- out/Gypsum
Flue gas in stack emission
Coal: Pulverized
Sea water-in /Limestone

24. III. Results of Mercury analysis
: Mercury concentration in coal fired power plant
Mercury concentration
Mercury concentration

25. III. Results of Mercury analysis
: Mercury concentration in coal fired power plant
Mercury concentration
Mercury concentration

26. III. Results of Mercury analysis
: Mercury concentration in coal fired power plant
Mercury concentration
Mercury concentration

27. III. Results of Mercury analysis
: Mercury concentration in coal fired power plant
Mercury concentration
Mercury concentration

28. III. Results of Mercury analysis
: Mercury speciation in flue gas streams
Plant 1
Plant 2-Unit6

29. III. Results of Mercury analysis
: Mercury speciation in flue gas streams
Plant 2-Unit 10
Plant 2-Unit 13

30. III. Results of Mercury analysis
: Mercury speciation in flue gas streams
Summary
The oxidized mercury (Hg2+) was most likely bound to gypsum slurry (140.69± ±38.92 μg/kg). However, Hg2+ absorbed in SWFGD was little (0.09±0.02 μg/L).
The total mercury concentration in the flue gas streams (i.e., Hg0, Hg2+ and Hg(p)) is correlated to the mercury content in the coal blends.
The flue gases at stack of the Plant 1 contained all three forms with a similar portion about 32-36%, whereas in the Plant 2, the flue gases contained a significant quantity of Hg0, possessing 67-81% of the total mercury.

31. III. Results of Mercury analysis
: Mercury mass balance in coal fired power plants
The overall Hg balance for each plant was around 38.6% for Plant 1, 82.2% for Plant 2/Unit 6, 109% for Plant 2/Unit 10 and 64.8% for Plant 2/Unit 13.
Plant 1 Bituminous
Plant 2 lignite/Unit 6

32. III. Results of Mercury analysis
: Mercury mass balance in coal fired power plants
The overall Hg balance for each plant was around 38.6% for Plant 1, 82.2% for Plant 2/Unit 6, 109% for Plant 2/Unit 10 and 64.8% for Plant 2/Unit 13.
Plant 2 lignite/Unit 10
Plant 2 lignite/Unit 13

33. V. Future mercury emission estimation

34. IV. Future mercury emission estimation
: Using the measured data from this study
Based on the actual data collected from this study, the emission factor calculations were performed following two scenarios: (1) from the direct stack emission of mercury (actual concentrations) and (2) from the uncaptured emission
Table Emission factors based on two calculation approaches
Calculation scenarios
Mercury emission factor (mg/ton)
Range
Mean±SD
1. Using the direct stack measurement
Plant 1
8.59±4.86
Plant 2
69.67±30.07
2. Using uncaptured Hg estimation
44.31±11.40
85.76±9.91

35. IV. Future mercury emission estimation
: Using the measured data from this study
Scenario 1
Future mercury emission estimated from stack measurement
In 2025, the predicted Hg emission is expected to decrease about 52.8% compared with those in This is because lignite consumption is projected to decline by about 62.5%, even though bituminous consumption is expected to increase about 28.6% compared with bituminous consumed in 2017.

36. IV. Future mercury emission estimation
: Using the measured data from this study
Scenario 2
Future mercury emission estimated from uncaptured mercury emission
In 2025, the predicted Hg emission is expected to decrease about 27.2% compared with those in This findings were slightly different from those in scenario 1 as the EF in this scenario is higher than that in scenario 1.
Mercury emission from bituminous power plant is also found to be higher than scenario 1, resulting in higher total Hg emission rate than the emission rate generated by scenario 1.

37. IV. Future mercury emission estimation
: Using the existing Hg removal efficiency of
relevant APCDs in literatures
Table Reviewed mercury removal efficiency of relevant air pollution control devices
Coal Type
APCDs
Hg removal Efficiency (%)
Country
Reference
Bituminous
PC+CS-ESP 27
China
Wang et al., 2010
PC+CS-ESP+WFGD 21
PC+FF+WFGD 71
USA
ICR, 2010
PC+SCR+CS-ESP+WFGD 66
Cheng et al., 2009
PC+SCR+CS-ESP+SW-FGD 29
Chen et al., 2008
Lignite 39
Table Removal efficiency of broiler
Power plant
Mercury removal efficiency (%)
Range
Mean ± SD
Plant 1
0.03±0.03
Plant 2
0.86±1.10

38. IV. Future mercury emission estimation
: Using the existing Hg removal efficiency of relevant APCDs in literatures
Case 1 Future Hg emission estimated from the removal efficiency of different APCD systems,
which was taken from literatures

39. IV. Future mercury emission estimation
: Using the existing Hg removal efficiency of relevant APCDs in literatures
Case 2 Future Hg emissions of 23 coal and lignite power plants and new power plants which were estimated by using the adopted Hg removal efficiency taken from literatures

40. Thank You