One of the pulverized coal fired thermal power plants in India intended to find the root cause of frequent boiler tube failures in three 210 MW units. Operation & Maintenance history and feedback from plant O&M team revealed that economizer tube failure was a frequent cause of forced outage. The plant under study used CFS (continuous fin surface) economizer with staggered tube arrangement in the 210 MW units. CFS staggered tube economizers originally appealed to many plant designers because the tortuous path created for the flue gas, enhanced heat absorption and the fins could capture heat and transfer it to the tubing. This made the CFS economizer less costly and easy for installation in a relatively small space. There is increasing use of lower quality high ash coals over the past few decades. Due to this fact an advantage of the CFS economizer design became a disadvantage. The narrow spacing in the tubes proved more susceptible to plugging and fly ash erosion. Literature study and the root cause analysis suggested that CFS staggered arrangement of economizer could be one of the prominent reason of failure of economizer tube bundle due to fly ash erosion. Flue gas flow simulation also highlighted that there is increase in velocity of flue gases across the economizer. A bare tube in-line configuration in place of existing CFS economizer was an alternative. To recommend an alternate economizer as solution, the merits of an in-line bare tube economizer were studied. Bare tubes arranged in-line are most conservative in hostile environments with high ash content, are least likely to plug, and have the lowest gas-side resistance per unit of heat transfer. A bare tube in-line economizer that can replace the existing finned tube economizer in the available space while meeting the existing design & performance parameters is recommended. An attempt was made to model & analyze the new economizer using computational fluid dynamics (CFD) tools in order to get firsthand experience and validate the results obtained using manual calculations. With limited computational resources and not so fine meshing, the performed CFD model analysis showed the expected trend but did not completely match the results.

The aim of study is to develop highly reliable and less time consuming steam dryness fraction measuring experimental setup. This method of dryness fraction measurement is based on throttling process which is obtained by using orifice plate. Calculation of orifice diameter was done by using ISO 5167 for given pressure drop. This paper deals with the conceptual design of orifice in a steam pipe line. The objective of the conceptual design is to obtain throttling process. Three parameters are chosen for the conceptual design: the diameter of the orifice, the aspect ratio between length and diameter and the entrance angle to the orifice. This work also deals with validation of calculated orifice diameter through CFD simulation for pressure drop in pipe line. To simulate the throttling process, the inlet condition of the orifice upstream flow is fixed at 10 bar and 180°C. The temperature and pressure is measured at the outlet of the orifice while steam is flowing through the pipe. An orifice diameter of 11.00mm is selected as the optimal value to keep throttling process. The resulting optimal orifice design will be used in steam pipe line.

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Diesel is extensively used as a fuel in prime movers, boilers and other power generation plants. The higher calorific value of diesel gives a measure of the effective chemical energy stored in a unit amount of fuel. The higher calorific value is required for the efficiency calculation of a machine and hence it directly affects the estimation of the gross turnover of a power plant. Traditionally the higher calorific value of diesel is determined by means of a bomb calorimeter; however, this procedure is time consuming and requires expensive, specialized equipment and oxygen gas. In this paper the authors have developed a unified correlation relating the higher calorific value of diesel with its density and kinematic viscosity both. Kinematic viscosity and density can be measured easily and quickly using standard laboratory instruments. Thus, developing the correlation has quickened the process of the estimation of the higher calorific value of diesel, and correlating two physical properties density and kinematic viscosity has made the estimation more accurate with a correlation coefficient of 0.985444 and a coefficient of determination of 0.9711 with a standard error of 1.012414 J/kg only.