Mercury Speciation Transformation During Coal Combustion - Mercury Emission and its Control in Chinese Coal-Fired Power Plants - page 72

and two-stage air-heater are laid out alternatively. The designed parameters of the
boiler are as in Table 4.15.

Table 4.15 Main designed operating parameters of boiler
Name Data

Number HG-410/9.8-YM15

Rated evaporation capacity 410 tons/h

Rated steam temp. 540 °C

Rated steam temp. 9.81 MPa

Steam drum operating pressure 11.28 MPa

Water temp. 220 °C

Cold temp. 20 °C

Air temp. 330 °C

Inlet temp. of air heater 30 °C

Exhaust gas temperature 134 °C

Excess air coefficient (the furnace exit) 1.2

Excess air coefficient (airheater exit) 1.39

Annual operational time 6000 h

Operational time at full load 5000 h

Boiler effeciency 92.07%

Furnace (width×depth) 9,980 mm×9,980 mm

Height from platform 39,000 mm

Height from drum centerline 42,600 mm

122 kW/m 3

Furnace volumetric heat load

3.1 MW/m 2 Sectional heat load

In general, the tangentially fired pulverized coal boiler is a typical case in China.
The tangential combustion system used here is to create well-arranged air circula-
tion and an even layout of the burning nozzle from up to down as follows: down-
draft secondary air, downdraft primary air, mid-downdraft secondary air,
mid-downdraft primary air, mid-updraft secondary air, updraft primary air, updraft
secondary air, OFA and tertiary air. As requested, the rotation of primary air keeps
in consistent rotation with the secondary air. Thus the imaginary tangential circle
diameter is 800 mm obtained accordingly. Exhaust gas from milling, considered as
tertiary air only, is injected from the upper side of the burner. The adjustable hori-
zontal bias burner with blunt body is adopted for use in primary air. As is
well-known, the parameters of air distribution in a furnace including primary,
secondary, tertiary air are necessary to do the simulation work equivalent to realistic
operational conditions. Other parameters involved in the ratio, temperature, veloc-
ity and height vary with the different kinds of air, and are described in detail in Table
4.16, which is substantially important for simulation investigation of mercury