Andrej Senegačnik

Influence of lignite composition on thermal power plant performance: Part 2: Results of tests

Abstract The results of measurements and experiments on two power plant units are presented. The treated coal is lignite with lower heating values ranging between 9 and 10 MJ/kg and with contents of ash about 20% and moisture about 38%. The influences of significant lignite composition components on heating value, boiler losses, boiler specific production of steam, own consumption of electric power, power consumption for coal grinding and flue gas desulphurisation etc. are discussed. The results of analyses and measurements are graphically presented.

Influence of lignite composition on thermal power plant performance: Part 1: Theoretical survey

Conversion of energy with the highest possible efficiency is of primary importance in processes with high intensity of energy flows, among which the most significant are those in thermal power plants. The paper deals with the influence of coal composition on the conversions taking place in power plants. The analysis of energy conversions treats, above all, the heat loss due to the exhaust flue gas. The analyses of the power plants use of electric powers are focused on the processes of coal pulverising and exhaust flue gas cleaning. The results of the analyses are graphically presented.

The Characterization of Pulverized-Coal Pneumatic Transport Using an Array of Intrusive Electrostatic Sensors

Fan/impact mills are commonly applied in the grinding and dilute-pneumatic transportation of lignite or brown coals with high moisture contents to the furnaces in large steam boilers. Each of the two to eight mills feeds pulverized coal into two or more burner nozzles. An online detection of the pulverized-coal mass flow distribution among the burners is vital for the control of the combustion process. Knowing the distribution, measures for the redistribution of the coal or, alternatively, for the adjustment of the combustion air flow according to the actual distribution can be employed. Determining the characteristics of a gas-solid two-phase flow using an electrostatic principle is a promising online method of measurement because it is robust and inexpensive. Furthermore, due to their better spatial sensitivity, rod sensors are more suitable for large rectangular ducts related to fan/impact mills than ring-, pin-, or arc-shaped sensors. Sets of 1-D and 2-D electrostatic sensor arrays with a corresponding data acquisition system were employed to determine the mass flow distribution in the cross section of the duct that feeds the pulverized lignite to the four burner nozzles. Various operating regimes for the fan/impact mill were tested. The time series of the signals from the electrostatic sensors were analyzed statistically. It was shown that the skewness, kurtosis, and autocorrelation time delay at the characteristic value can indicate different grinding qualities of the coal.

Operating reliability of a conventional power plant

Abstract A Markov model is a mathematical model of reliability. This article discusses its adaptation to power plant operations. It is demonstrated that this model is a successful tool for time-dependent reliability determination. The adapted model was compared with available statistical data from major power plant operations. It is shown that power plant behaviour is well described by the analytical solution, which is also a good prediction of short- and long-term reliability.

Influence of temperature profile in an annular shaft kiln on calcination

The paper discusses an experimental measurement of the vertical temperature profile and kiln gas composition in an annular shaft kiln. The results obtained confirm that calcination in the kiln begins at a temperature between 820°C and 830°C. From energy balance, kiln gas composition and the samples of partially burned stones from the kiln the average heat transfer coefficient from kiln gases to the stones is determined, as well as the calcination distribution within the kiln. Modelling of the calcination process in an annular shaft kiln was performed on the basis of the measured temperature profile. The results of this model were in good agreement with those for samples of partially calcinated stones taken from the area of the lower and upper burners.