For the analysis of the heat applied to equipment outside the system boundary

the energy utilized was outside the GB/T 10184 standard

and the boiler efficiency calculation could not take advantage of the existing standard. The external heat loss of hot air was divided into two categories: hot air reuse and hot air non-reuse. Based on the GB/T 10184 calculation framework

the calculation methods of these two categories of external heat loss of hot air were proposed. Taking a 350 MW boiler as a practical example

under the same load

continuous operation of hot air external use and shutdown of hot air external use were compared. According to the actual test data and analysis results

the calculation method was used to compare the actual operating conditions. The influence of external loss of hot air on boiler efficiency was analyzed. The results showed that the test results of combustible materials in two working conditions were basically the same. The external loss of hot air in T01(cold air recovery)was 0.82%

the external loss of hot air(cold air nonrecovery) was 0.13%

and the external loss of hot air in T02 was 0. The measured boiler efficiency in T01 and T02 conditions was 93.10% and 94.00% respectively. The operation of external hot air system reduced the boiler efficiency by about 0.9 percentage point.