Thermal design of waste heat boiler Shandong flue gas waste heat boiler supports customization

Description :

　　Thermal calculation of waste heat boiler

　　The purpose of thermodynamic calculation

　　waste heat boilerThe purpose of thermodynamic calculation is to select the form and structure based on the given working conditions of the boiler, such as the composition, properties, flow rate, inlet and outlet parameters (temperature, pressure), feedwater temperature, and steam parameters, and to determine the capacity and heat transfer area of the furnace, as well as the layout and size of heat exchange elements.

　　Thermal calculation is the foundation of waste heat boiler design. After completing the thermal calculation, it provides necessary data and conditions for fluid resistance calculation, water circulation calculation, and component strength calculation of the boiler. So thermal calculation is an important component of design.

　　The steps of thermal calculation

　　Physical property calculation

　　Calculate the physical properties related to the mixed gas, such as viscosity, density, thermal conductivity, specific heat capacity, enthalpy, etc., based on the composition and parameters (temperature, pressure) of the hot gas. When calculating, a list should be included, which will make subsequent calculations convenient, time-saving, and easy to check for errors.

　　Heat exchange calculation

　　According to the inlet and outlet conditions of the hot gas, the heat transfer amount is calculated from the thermal balance, and then the evaporation capacity of the waste heat boiler is determined.

　　selection

　　Select the form, structure, and materials of the waste heat boiler based on the temperature and pressure of the hot gas and steam, as well as the physical and chemical properties of the hot gas.

　　Calculation of heat transfer area

　　(1) Preliminary arrangement of heat exchange surfaces, arrangement of tube sides, and drawing of a schematic diagram of the waste heat boiler.

　　(2) Calculate the average temperature difference.

　　(3) Based on experience or referring to the thermal calculation and operating data of similar waste heat boilers, estimate the heat transfer coefficient K, or estimate the total heat transfer K based on the initial estimation of the heat transfer coefficient inside and between pipes, as well as the thermal resistance of scale and fouling.

　　(4) Preliminary calculation of heat transfer area based on the basic heat transfer equation.

　　(5) Calculate the actual heat transfer area based on the schematic diagram of the waste heat boiler. For general waste heat boilers, if the calculated actual heat transfer area is 10% -20% greater than the preliminary calculated heat transfer area in item (4), it is considered that the designed basic dimensions are appropriate, and the heat transfer area calculation is considered complete.

　　If the actual heat transfer area is not within the above range compared to the initially calculated heat transfer area, the tube bundle must be increased or shortened to make the actual heat transfer area 10% -20% larger than the calculated heat transfer area. The use of increasing or shortening the tube bundle to increase or decrease the heat transfer area will not affect the arrangement of the tube bundles and the calculation of K values mentioned above. Otherwise, if the method of increasing the number of tubes is adopted, the tube bundles must be rearranged and the above items must be recalculated.

　　5. Verify heat transfer hazardous areas

　　Perform the following verification based on thermodynamic calculations:

　　(1) Calculate the wall temperature of the waste heat boiler and verify the allowable temperature of the installation pipe;

　　(2) Calculate the critical heat load and verify the heat load on the heat exchange surface.

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• Thermal design of waste heat boiler