A novel multi-indicator VSBM-boiler model: Assessing the economic-thermodynamic performance of utility boilers

With the increasing integration of renewable energy, coal-fired utility boilers in China are expected to operate frequently at low loads. However, this study revealed that low load could reduce boiler efficiency. The Time-of-use (TOU) price serves as an economic incentive to address this issue. However, operation during valley periods also leads to poor economic returns. In this study, a novel multi-indicator network SBM model is proposed, which allocates weights based on the preference for indicators rather than divisions. By applying the hybrid economic-thermodynamic objective function to 1391 operating conditions, the relative efficiency trends across loads and periods for a supercritical boiler were identified. The application shows that the proposed model has better discrimination in the context of the TOU price, and that operating at a load below 32.46 % could cause a 26.08 % decrease in the thermodynamic efficiency, and operating in Valley periods could lead to a 35.45 % decrease in the economic efficiency. In addition, the average overall efficiency of low-load Valley operating conditions is only 59.71 % of that of all operating conditions. This study is the first to quantify the thermal efficiency of the production frontier.