Principal Research Results

The Functions and the Characteristics of Combustion and Flue Gas Treatment onthe Coal Combustion Characteristic Evaluation Test Facility− The Role on the Development of the Advanced Pulverized CoalCombustion Power Generation Technology−
BackgroundIn a pulverized coal-fired power generation, the diversification of the coal type, the reduction of generation cost and further
improvement are an extremely important task. To perform these tasks for the advancement of pulverized coal combustion power generation technology, two research subjects were set in CRIEPI. One is the development of the combustion technology for up-gradingash quality, which reduces unburned carbon concentration of the ash and the fluctuation of the concentration, controlling the generation of NOx to various coals. The other is the development of the integrated evaluation technology for coal adaptation to power plants,
which makes the adaptability of unused coals to power stations clear. To advance this project, the coal combustion characteristic evaluation test facility (Coal feed rate: 300kg/h , the name commonly called: MARINE facility, Figure 1) that was able to simulate thecombustion of actual power plants and the operating conditions of the flue gas treatment system was set up in 2002.

Objectives
To contribute to the development of the advanced pulverized coal combustion technology, the combustion characteristic andthe flue gas treatment characteristic of the MARINE facility are clarified.

Principal Results(1) The main features and functions of MARINE facility
・The MARINE facility has the vertical furnace where three burners are arranged in the upper, middle and lower stage. The operating
condition and the blending coal ratio of each burner can be changed to develop mono-coal and blending coal combustion technology of the low rank coal (sub-bituminous coal) in multi-burner system. Moreover, the combustion in the multi-burner system of theactual boiler can be simulated by enabling the change in the two staged combustion ratio and the air injection position. In addition,
there are the burner functions that can adjust the fuel feed rate, the operating condition, the kinds of fuel, and the blending fuel ratioetc.
・To study on the behavior of various materials such as NOx, SOx, ash and trace elements etc in the plant. , NOx removal equipment(SCR method ＊ 1), the electrostatic precipitator and the desulfurization equipment (limestone- gypsum method) similar to actual
power plants are adopted.
(2) Combustion and flue gas treatment characteristics
The influence of the two staged combustion air ratio and the air injection position on the characteristics of NOx emission
and unburned carbon concentration (Figure 2), and the relationship between NOx concentration and unburned carbon concentration,
Uc (Figure 3) were clarified. These characteristics of the MARINE facility were similar to those of the existing coal combustion test
facility (the name commonly called: BEACH furnace ＊ 2) where huge test data and the correlation with actual power plants were obtained. In addition, it was confirmed to be able to simulate the combustion characteristic of actual power plants and to have the possibility of the direct evaluation of the unburned carbon concentration, shape and specific surface area of ash because the unburned carbon concentration of the MARINE facility is almost the same as actual power plants at the same NOx concentration (Figure 3). For theflue gas treatment, the basic performance of the NOx removal equipment, the electrostatic precipitator and the desulfurization equipment (Figure 4 and Figure 5) were clarified, and also it was shown that there is the great possibility to evaluate the behavior of various
materials such as NOx, SOx, coal ash and trace elements etc.

Future Developments
The MARINE facility will be used for the developments of the combustion technology for up-grading ash quality to various
coals, the integrated evaluation technology for coal adaptation to power plants and detailed investigation for the behavior of trace elements.
Main Researcher: Hiromi Shirai, Ph.D.,
Senior Research Scientist, Fuel and Combustion Engineering Sector, Energy Engineering Research Laboratory
Reference
H. Shirai et.al, 2004, “The functions and the characteristics of combustion and flue gas treatment on the coal combustion characteristic
evaluation test facility”, CRIEPI Report, W03025＊1： Selective Catalytic Reduction method: NOx is decomposed to N2 and H2O on the catalyst using NH3＊2： Horizontal furnace with single burner (Coal feed rate: 100kg/h)

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C. Harmonization of energy and environment

Main characteristics
Functions
The temperature profile in actual boilers can be ・The vertical-type furnace with three burners (CI-α burner, 100kg/h×3) was installed.
simulated.
・Two different kinds of fuel can be supplied for each burner (Each burner has two bins.）
Coal, biomass and other solid fuels can be
・The burners have tilting mechanism (±10deg), and clearance between burners can be changed
supplied, and advanced burner systems can be(±100mm).
developed by optimizing the burner position,・Size of pulverized fuel can be changed (50%size : 10〜70μm).
size of pulverized fuel, co-firing conditions ,・Distribution of temperature and gas compositions (O2, CO, CO2, NOx, SO2) can be changed.
etc.
・The fouling test sections and heat flux probes were installed.
・De-NOx equipment with SCR method was installed.
The exhaust gas treatment equipments, which
・The charging method and operating temperature of the electric static precipitator can be changed.
are operated in various temperature conditions,・Desulfurization equipment with limestone-gypsum method was installed.
were installed, and the behaviors of・Ash can be sampled from each exhaust gas treatment equipment.
environmental pollutants can be evaluated.
・HCl, HF and mercury can be monitored continuously.
The Emulsion fuels can be evaluated.
・Three heavy oil burners were installed.

Fig.1 The process flow, features and functions of MARINE facility

125

0.8

20
Two-staged combustion
ratio : 30%

0.6

150.4

100.2

50

Unburned carbon concentration in fly ash Uc [%]30
NOx (MARINE facility)
NOx (BEACH furnace）
Uc (MARINE facility）
Uc (BEACH furnace)

Uc(two-staged)/Uc(Non-staged) [-]NOx(two-staged)/NOx(Non-staged) [-]1.200

10203015Newlands coal
MARINE facility
BEACH furnace
Large scale test furnace (1.5t/h single burner)

10Emission area on actual boilers
500200z/D, [-]z ： Distance from burner to two-staged combustion air port [m]D ： Diameter of burner [m]

9796
9590
130
Operating temperature [℃]

At 90 ゜C, the efficiency at
continuous charging ishigher than that atintermittent charging. At130 ゜
C, the efficiency atcontinuous charging islower than that atintermittent because
electric resistance of ash
becomes higher.

Desulfurization efficiency [%]Collection efficiency [%]98800

1000Fig. 3 Emission characteristics of NOx and unburned
carbon concentration in fly ash

Fig.2 Effect of position of two-staged combustion air
port on NOx and unburned carbon concentration

99600

Unburned carbon concentration is almost the same as
actual power plants.

The characteristics of NOx and unburned carbon atchanging air injection position are similar to those theBEACH furnace

Continuous charging
In100
termittent charging

400

NOx Concentration(O26%) [ppm]

100
9080
L/G=27
L/G=22Example on an actual plant

7060
3.5

44.555.5
66.5
pH of slurry in absorption tower [-]The efficiency of more than 90% is obtained at the same pH
range with actual plants. The efficiency becomes higher as theratio (L/G) of sprayed absorbent L[r/ｈ] to treated gas G[m3/h]
increase.

Fig.4 Effect of charging method on collection efficiency

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Fig.5 Relationship between pH of absorbents
and desulfurization efficiency