Mitsubishi Heavy Industries Technical Review Vol. 54 No. 3 (September 2017)
53Features and Operational Results of South Korea's First
1000 MW Class Coal-Fired Ultra-supercritical Boilers- Korea East-West Power Co. Ltd. Dangjin
Thermal Power Plant Units No. 9 and No. 10 -M i ts u b i s h i H i ta c h i P o w e r S y s t e m s , L t d .

In South Korea, power demand is steadily increasing in response to economic growth. As theconstruction of new power plants is planned in the country, developments in the field have been
attempted one after another, such as increasing the power generation output of the units andimproving their steam conditions. Amid such a trend, Dangjin Thermal Power Plant Units No. 9and No. 10 of Korea East-West Power Co., Ltd. were planned as the first large-capacity 1,000 MWclass ultra-supercritical boilers in South Korea, and have continued stable commercial operation
since the commencement of operations in 2016.

|1. Introduction
As the domestic electric power market has seen sluggish growth, we targeted overseas salesof our high capacity ultra-supercritical boiler technology cultivated through the power plant
market in Japan, and received an order for South Korea's first 1000 MW class coal-fired
ultra-supercritical boilers for Dangjin Thermal Power Plant Units No. 9 and No. 10 in 2010. Thismeans that our company's numerous achievements and technological capabilities are highlyevaluated. This paper presents the features of the Dangjin Units No. 9 and No. 10 boilers thatcommenced commercial operations in 2016, as well as an overview of the applied technology.

|2. Overview of boiler design
2.1Overview

Table 1 shows the planned specifications of the boiler. The steam conditions are equivalent
to the latest power plants in the domestic power generation market, and the boiler was planned to
be used in a highly-efficient plant. The specifications reflect a design that allows for 50% mixed
firing using bituminous coal and subbituminous coal as the fuel.
Table 1 Planned specifications of boiler
Dangjin Power Plant

Item

Unit No. 9Unit No. 10
Ultra-supercritical variable pressure
reheat-type once-through boiler
1,020MW

Boiler typeOutputSteam flow

3,033t/h

Steam condition
Fuel

25.4MPa(g) / 603°C / 603°CBituminous coal and subbituminous coal mixed firing

Operation start

2.2

July 2016

September 2016

Major features

Figure 1 shows the boiler side view. The boiler's design adopts the latest technologies oflarge-capacity ultra-supercritical boilers cultivated in the domestic power plant market, and has thefollowing features.

Mitsubishi Heavy Industries Technical Review Vol. 54 No. 3 (September 2017)
54

Figure 1

Boiler side view(1) Subbituminous coal mixed firing
The characteristics of subbituminous coal are that it has a larger amount of moisture, alower calorific value, and a higher ash adhesion property than bituminous coal. As measuresagainst the high ash adhesion property, a sufficient furnace size is secured, the shape and thepitch of the heating surface are optimized, as is the arrangement of the soot blower.
(2) Adoption of spiral water wall structure
The boiler employs a combination of a spiral water wall structure and the opposed firing
method that has been proven in many domestic and overseas large-capacity boilers. This
realizes a design with a reduced fluid temperature unbalance at the furnace outlet.
(3) Adoption of large-capacity pulverizer
Since subbituminous coal has a lower calorific value, coal consumption is increased incomparison with that of bituminous coal. However, this boiler adopts a large-capacity
pulverizer with a capacity 1.5 times larger than conventional pulverizers to be able to handle
the increased coal consumption using the same number of pulverizers and type as existing
technology.
(4) Adoption of low NOx burnerThis boiler adopts the NR3 burner, which is a low NOx burner with many achievements
including its use in the latest domestic plants, to reduce the environmental burden. This NR3burner enhances the flame stabilizing property to promote in-flame NOx reduction, and alsoenables the reduction of unburned carbon content, which normally impedes NOx reduction.

|3. Operational results
As a result of commissioning, it was verified that this boiler is capable of stable operation inwhich the steam temperature characteristics, combustion characteristics, etc., achieved the planned
values even when subbituminous coal is used as fuel. In terms of the combustion performance,NOx and unburned carbon content were extremely low and good results were obtained. For theboiler performance, it was comfirmed that planned boiler efficiency was achieved. This indicates
our high technological strength and reliability in ultra-supercritical boilers that are designed tomake the use of subbituminous coal possible.

|4. Future development
The boilers for Dangjin Thermal Power Plant Units No. 9 and No. 10 are South Korea's first
1000 MW class coal-fired ultra-supercritical boilers that were adopted due to our highly-evaluatedtechnology and reliability. During commissioning, the high boiler performance was confirmed andfully satisfied the customer's expectations. This boiler will be a model plant for next generation oflarge-capacity 1000 MW class ultra-supercritical boilers that are planned not only in South Korea,
but also elsewhere in Southeast Asia. Reflecting the operational results of this boiler, we willcontinue to supply even more reliable boilers.