## 3 Materials and Methods  
The first step in determining the optimal operating parameters of the burner began with separately measuring the velocities of the secondary air, primary air, and the mixture of primary air and pulverized coal within the pipe. Next, the primary air and pulverized coal mixture sample was taken from the pipe according to the ASME PTC 4.2 Coal Sampling Standard [22]. Pulverized coal samples taken from the pipe were prepared under laboratory conditions for analysis according to the ASTM D 2013 coal sample preparation standard [23]. The proximate analyses of the pulverized coals prepared for analysis, including moisture (ASTM D 3173), ash (ASTM D 3174), volatile matter (ASTM D 3175), and gross calorific value (ASTM D 5865), were performed according to the analysis methods specified in the standards [23]. Additionally, a sieve analysis was performed to determine the particle size distribution of the pulverized coal. The optimal operating parameters of the burner were determined based on the evaluation of the data obtained from the analyses. Figure 2: A schematic representation of the industrial experimental setup. The velocity of the pulverized coal and primary air mixture was measured at the measurement port, indicated as number 9 in Figure 1, which is mounted at the burner inlet. Figure 3 shows the pipe cross-section, differential, and static pressure measurement equipment. The differential pressure probe shown in Figure 3a was inserted into the pipe through the measurement port, perpendicular to the flow of the pulverized coal-air mixture according to the ASME PTC 4.2 standard [22]. As shown in Figure 3b, the interior of the circle is divided into circles with equal areas on the axial axis. The differential pressure values measured by the probe at the points where the outer circumference of these equal-area circles intersect the radial axis of the pipe were recorded. After the measurement, the average of the differential pressure values measured along the radial axis was taken. The static pressure and temperature values inside the pipe were measured using the static pressure probe shown in Figure 3c. The probe was inserted into the pipe through the measurement port perpendicular to the flow of the pulverized coal-air mixture and pushed to the center of the pipe. The static pressure and temperature values were recorded from the manometer connected to the probe. The air density inside the pipe was calculated by applying the measured static pressure and temperature values to the ideal gas equation in (1). The air velocity inside the pipe was determined by applying the air density, the average differential pressure value, and the probe's k correction factor to the Bernoulli equation in (2). The airflow rate was obtained by multiplying the air velocity inside the pipe by the pipe's cross-sectional area. \[\rho=\frac{\mathrm{P}}{\mathrm{RT}}\, \tag{1}\]  
where,  
P: Static Pressure (Pa),  
R: Universal gas constant (R = 287 J/kgK),  
T: Fluid Temperature (K),  
\(\rho\): Fluid Density (kg/m\({}^{3}\)). The simplest form of the Bernoulli Equation (2) is:  
\[\mathrm{P_{1}}+\frac{1}{2}\rho{V_{1}}^{2}+\rho\mathrm{gh_{1}}=\mathrm{P_{2}}+ \frac{1}{2}\rho{V_{2}}^{2}+\rho\mathrm{gh_{2}}, \tag{2}\]  
Figure 3: The cross-section of the pipe entering the burner. (**a**) Differential pressure probe and measurement equipment, (**b**) view of the differential pressure measurement at 12 points along the radial axis of the coal pipe, and (**c**) static pressure probe. In the Bernoulli Equation (2), when the initial velocity is zero and the differential pressure measurement probe moves along the x-axis, the fluid's velocity at the second point is calculated according to Equation (3): (h\({}_{1}\), h\({}_{2}\) = 0, V\({}_{1}\) = 0).