Boiler startup under conditions of convective heating of the highly reactive coal dust

Abstract

Experimental research of conditions and characteristics of ignition of the pulverized coal (with a particle size of approximately 80 μm) of different-type brown coals (1B, 2B, and 3B) during convective heating by a heated airflow (at a temperature of 425–600°С and velocity of 1–5 m/s) is carried out. The use of low-inertia thermocouples, a high-speed video camera, and dedicated software has made it possible to determine the minimum oxidizer parameters needed for coal dust ignition, and the approximation dependences of a main characteristic of the process under study―ignition delay time―on the air temperature. Results of experimental studies provide a basis for developing an optimal scheme of the boiler startup without heavy oil, which differs from the known schemes by the relatively low energy consumption for fuel-burning initiation. By example of the BKZ 75-39FB boiler, the economic usefulness of applying the boiler startup without heavy oil is shown. This scheme can be implemented using the proposed ignition burner that functions as a part of the direct system of pulverized-fuel preparation.