Abstract
Gross calorific value (GCV), also known as the higher heating value (HHV), refers to the overall
heat output when coal undergoes complete combustion. The measurement or estimation of
the GCV of coal is used in calculations for boiler efficiency, plant production costs, and design
calculations. The measurement or estimation of the GCV of coal is also essential for efficient
power plant operation. The GCV of coal is paramount in analyzing coal fired power plant
(CFPP) performance, therefore it should be easily accessible for efficient plant performance
condition monitoring.
Numerous researchers have developed methods to estimate the GCV of coal using regression
analysis. Regression analysis consists of linear/multilinear regression correlations developed
using the proximate and ultimate analysis of coal as input parameters. The coal samples
utilized to develop these regression models are from specific geographical areas and usually
provide inaccurate results when used on coal from a different geographical area. There are
also experimental methods used to measure the GCV of coal, namely the differential scanning
calorimetry (DSC), which involves sending coal samples for laboratory analysis and requires
the use of expensive equipment requiring skilled operators, which frequently causes delays in
receiving results. Literature review indicated that online monitoring of the GCV of coal has not
been extensively explored, and real-time plant data has not been considered to estimate the
GCV of coal. This gap in literature motivated this study to use real-time plant data to estimate
the GCV of coal.
This study investigated a boiler with a power output of 620 MW, which operates using lowgrade
bituminous coal that has an ash level of up to 42% and a GCV of 15–16 MJ/kg. The study
focused on a dry-bottom furnace coupled with a subcritical drum boiler layout with 36
opposing swirl burners burning pulverized coal, 18 on each of the front and back walls of the
furnace. Static vanes are employed by the burners to swirl the secondary air annulus, thereby
enhancing combustion efficiency. The system generates 477 kg/s of high-pressure steam at
165 bar and 540°C, in addition to low-pressure reheat steam at 40 bar and 540°C...