Aerodynamic characteristics of modular cooling wall for a 50 MW coal-fired scCO2 boiler

Abstract

Supercritical carbon dioxide (scCO₂) coal-fired power generation is transitioning from conceptual validation to industrial demonstration. China is planning to build a 50 MW scCO₂ boiler coal-fired power unit. Focusing on the challenges of large mass flow rate and large pressure drop in scCO₂ boilers, this paper takes the scCO₂ boiler as the research object and focuses on the configuration and aerodynamic characteristics of the modular cooling wall. In this paper, the boiler cooling wall is divided into four sections, and the working fluid is split into two streams before entering the boiler, with each flowing through different heat transfer surfaces, thereby reducing frictional pressure drop. To study the aerodynamic characteristics of the boiler in a 50 MW scCO₂ unit, this paper constructs an aerodynamic calculation program based on the loop flow method. Furthermore, it presents a design method for the throttle ring at the loop inlet, and analyzes the flow distribution and tube wall temperature of the vertical tube screen before and after the installation of the throttle ring at the loop inlet. The study found that after installing the throttling ring, the loop flow rates were well matched with the thermal load, and the outlet gas temperatures of the working fluid in each loop were approximately the same. Additionally, the installation of the throttling ring reduced the maximum outer wall temperature of the Part 2 loop by approximately 15 °C, and the outer wall temperature of the entire cooling wall was controlled to within 665 °C.