Optimized Design of Water Walls of Supercritical and Ultra Supercritical Boilers

The following design details of supercritical and ultra supercritical boilers water walls are being delineated: adoption of rifled tubes in the lower radiation zone's water wall, lowering the mass flow rate, well mastering the thermophysical characteristics of the supercritical fluid, reducing enthalpy increments of the working medium, diminishing the heat delivery and temperature deviations of the water walls, lowering local heat load, raising the safety margin, optimally selecting the minimal once-through circulation load by comprehensively considering expenditures required by the starting system, the load variation range as well as the load following capability during swift load variations, for meeting the set's cyclic operation requirements. A theoretical analysis of the medium's flow characteristics in the vertical water wall tubes of a 1000MW ultra supercritical boiler is presented, and it is pointed out that, during operation, much attention should be paid to the influence of coal quality variation and to the strict control of water quality.