Unification of Design Solutions for Two Groups of Drum-Type Gas-Fired Boilers with Different Capacities and Steam Parameters

Difficulties in implementing methods for unification of design solutions for power-generating boilers of different capacities are considered. The unification of the designs could result in cost reduction at all stages of boiler manufacturing. Approaches are described that were used to search for solutions for two groups of drum-type gas-fired boilers with capacities of 75–150 and 200–320 t/h that function at different values of the superheated steam pressure and temperature. The selection of the design solutions for the boiler-flow diagrams and the method for the arrangement of the burning process common for all boilers, as well as the evaluation of the efficiency and reasonability of the adopted solutions, have been validated. Considering the experience of manufacturing and operating the boilers and the reliability and efficiency of the heating surfaces, the design solutions are set forth and justified, which include the selection of the material of the tubes and their diameters and wall thickness, the number of parallel coils from one cross section, the coil spacing, and the arrangement of the coils. The criteria for determining the geometry of the heating surfaces for the basic boilers of each group have been established. The possibility of extending the geometric parameters on the boilers of other capacities is considered. The variants of the thermal designs for the boilers operating at 100, 50, and 30% loads calculated using the Boiler Designer and Furnace software programs are provided. The causes as to why the required superheated steam temperature cannot be achieved in all boilers at low loads at the excess air coefficients at the furnace exist specified in the current normative documents have been analyzed. Depending on the parameters that determine the arrangement of swirl burners in the furnace, two different but stable burning process patterns are possible.