Siti Sarah Ain Fadhil

The effect of loading condition on the formation of residual swirl in tangentially-fired boiler

This paper presents an investigation of the behavior of reacting flow in industrial boiler with particular interest given towards the effect of boiler load conditions to the velocity and temperature distributions in the furnace chamber. The map of three-dimensional velocity in the furnace domain is manipulated with appropriate mathematical relations to give a clear and concise representation on the swirl effect under the influence of boiler loading condition. From the investigation, it is clear that the residual swirl formed in the furnace is highly influenced by the loading condition. High load condition results in strong combustion gas velocity and vice versa. As opposed to the velocity magnitudes, it is also interesting to notice that the swirl condition is hardly influence by the loading condition.

Influence of furnace cross section on the flow and velocity distribution in tangential firing furnace

This paper presents an investigation on the influence of different furnace cross sectional configurations on the flow and velocity distribution in a small-scale tangential firing furnace. The flow and combustion of natural gas in three furnaces of different cross section are simulated numerically using CFD. The results show that velocity distribution is non-uniform along the width and depth of the furnace in rectangular furnace while square cross section gives uniform distribution. The effect of furnace cross section on the tangential velocity is more obvious when the length difference of the width and depth of the furnace is larger. The axial velocity is found to be highly influenced by the furnace cross section.

CFD analysis of temperature imbalance in superheater/reheater region of tangentially coal-fired boiler

This paper presents a CFD analysis of the flow, velocity and temperature distribution in a 700 MW tangentially coal-fired boiler operating in Malaysia. The main objective of the analysis is to gain insights on the occurrences in the boiler so as to understand the inherent steam temperature imbalance problem. The results show that the root cause of the problem comes from the residual swirl in the horizontal pass. The deflection of the residual swirl due to the sudden reduction and expansion of the flow cross-sectional area causes velocity deviation between the left and right side of the boiler. This consequently results in flue gas temperature imbalance which has often caused tube leaks in the superheater/reheater region. Therefore, eliminating the residual swirl or restraining it from being diverted might help to alleviate the problem.

CFD Investigation of Pollutant Emission in Can-Type Combustor Firing Natural Gas, LNG and Syngas

CFD investigation of flow, combustion process and pollutant emission using natural gas, liquefied natural gas and syngas of different composition is carried out. The combustor is a can-type combustor commonly used in thermal power plant gas turbine. The investigation emphasis on the comparison of pollutant emission such in particular CO2, and NOx between different fuels. The numerical calculation for basic flow and combustion process is done using the framework of ANSYS Fluent with appropriate model assumptions. Prediction of pollutant species concentration at combustor exit shows significant reduction of CO2 and NOx for syngas combustion compared to conventional natural gas and LNG combustion.

Temperature Distribution Analysis on Syngas Combustion in Microgas Turbine

Gas turbines are capable to utlize variety of fuel including natural gas, fuel oils and synthetic gas. It has environmental advantages and thus gas turbines are favourable in the power generating industries. The use of synthetic gas or syngas may reduce the CO2 and NOx emissions. The efficiency of syngas is comparable with natural gas. With the current constrain on the environmental issues, the use of syngas in gas turbines has been increasing. Despite its many advantages, the study on the combustion characteristics still remains a challenge, due to its variety fuel components. This paper aims to discuss the CFD analysis on the flame and flue gas temperature distribution in a full scale microgas turbine operating on syngas. Three cases were simulated with variety of natural gas concentration. A base case firing natural gas (100% methane) was first established using actual operation. Validation on the combustion model is made by comparing the flame temperature distribution of methane with reasonable accuracy. Simulation results with syngas show similar flame temperature distribution as natural gas combustion. The average temperature is much dependent on the composition of methane in syngas. The highest temperature given by syngas is made from the highest methane composiotion.

CFD Analysis of Temperature Imbalance in Full Scale Tangentially Fired Coal Boiler

Tangentially fired boilers are widely used in generating electricity power due to its advantage of distributing heat evenly to all furnace walls. However, this type of boiler poses common temperature deviation at the upper furnace which may lead to temperature imbalance. This consequently may reduce the performance of the boiler which cannot be simply ignored. This paper investigates the flow and temperature imbalance in a 700 MW coal-fired boiler at full load and reduced load conditions. The effect of loading condition towards the temperature imbalance is investigated. It is observed that temperature imbalance occurs at the reheater plane between left wall and right wall where higher temperature was found near the left wall. Temperature imbalance is influenced by the loading condition, the higher the loading the higher the imbalance.