The boiler efficiency programme module may be applied to boilers fired pulverised coal, oil, gas, biomass, as well as to fluidised bed boilers and heat recovery steam generators. The module software enables also calculations to be performed for simultaneous combustion of several fuels.
Fluidised bed boiler efficiency screen graphics
The module calculates thermal balance, heat loss and efficiency on the basis of current measurements that have been taken from a database or from the control system. The results in each calculation cycle are made available to operators in the form of screen graphics. The data obtained from these calculations are also recorded in the database and can be analysed at a later date.
Depending on the boiler size and fuel type, the calculations are carried out either by the direct method or by the loss method. For coal fired boilers, the efficiency is calculated by determining the main heat loss. In addition, the flue gas composition necessary for calculations is determined by iterative procedures.
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The applied calculation methodology is based on the relationships described in standard PN-EN 12952-15 of 2006 "Water-tube boilers and auxiliary installations. Part 15: Acceptance tests." Also other methods may be applied for efficiency calculations, including the method described in the ASME standard.
The operators are informed of the current value of heat loss, the thermal balance components, the fuel chemical energy used for steam generation and a number of parameters, of which some are listed below.
The fuel composition. This is determined on the basis of chemical analysis of individual fuels (for simultaneous combustion of basic fuel and additional fuels). In addition, the current composition of the fuel composite burned is determined on the basis of the measurements taken of the outlet flue gas composition.
The dependency of the boiler flue gas loss on the excess combustion air and the flue gas temperature. This dependency is calculated based on the current conditions, i.e., for the current flue gas composition, the oxygen content in the flue gas and the flue gas temperature at the boiler outlet.
The dependency due to unburned carbon loss on the combustion conditions. The unburned parts in fly ash and slag are systematically estimated with neural models. The current loss value, and its dependency on the factor that currently has the strongest influence on this loss are then determined. A simpler solution is when the fuel composition laboratory analysis result is used instead of the neural model.
The operators, having quantitative information on the influence of individual parameters on the boiler efficiency, are then able to individually take cost-effective measures during the boiler operation. |
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