The Study On Thermodynamic Calculation Method And The Superheater Numerical Simulation Of The Supercharged Boiler

The steam power plant is one of main marine power plants. Supercharged boiler, as thecore of marine steam power plant, has many advantages, including light weight, small size,high mobility, economy and etc. It is of great importance to study marine superchargedboiler.This thesis takes1.5t/h small test supercharged boiler as main object of study, and thesteam power system and body structure are introduced. The check calculation of the smalltest supercharged boiler at the design full load, full load and75%load after replacing fuel isconducted with73Standard Calculation Method, and calculated results demonstrates thereasonableness of design. The heat transfer performance experiments are conducted under50%、75%and100%loads, and experimental data are obtained. After analyzing, it shows that75%load reflects the thermal properties of the boiler well. Comparing these data with checkcalculation results, calculation methods and selection of thermal performance parameters, andother key issues in73Standard are investigated. The study indicates that burning coefficientM=0.48in73Standard is not suitable for the thermodynamic calculation of this boiler. Theselection method is redefined, and M=0.58. The effectual thermal coefficient of evaporation Tubebundle in the supercharged boiler is re-determined that=0.65, the effectual thermal coefficientof superheater0.635, and that of coal economizer=0.64; The reasonable conclusionswith modified thermodynamic calculation method are gained. The thermodynamiccalculation for boiler is also carried on with "KB76" method, with too high calculated outlettemperature, showing that the method is not suitable for boiler thermodynamic calculation.The overall1:1three-dimensional flow computation model of supercharged boiler isestablished with FLUENT software. The flue gas and steam flow in superheater are described,and heat transfer in it is numerical simulated with N-S equations and Realizale k turbulence model. And the results that the steam flow, temperature, wall heat loads,convective heat transfer coefficient on surface, tube wall temperature distribution areobtained. Through the comparison of the experimental data, improved73standards methodsand results of numerical simulation, it shows that the superheater outlet steam temperaturecalculated by the numerical simulation has deviation of6℃with experimental measurement,which is rather small; fuel gas outlet temperature, the mean convective heat transfercoefficient of external wall and average fuel gas velocity fit well with thermodynamic calculation results. It is feasible to apply numerical simulation method for boilerthermodynamic calculation and the real distribution of the flow field reflects is reflected indetail.