Hot blast heater recycling low-heating-value gas and combustion method

The invention discloses a combustion method recycling low-heating-value gas. The method comprises the following steps that coal powder is ignited and combusted through a coal powder combustion chamber (2) at the bottom of a hot blast heater (1), high-temperature hot smoke is generated, the temperature of a hearth of the hot blast heater (1) can be increased through the hot smoke so that the temperature can reach the ignition point of pyrolysis gas or above; pyrolysis gas is conveyed into a pyrolysis gas combustion chamber (3) in the middle of the hot blast heater (1), heat is supplied to the pyrolysis gas combustion chamber (3) through the hot smoke generated in the coal powder combustion chamber (2), ignition combustion is carried out on the pyrolysis gas in the high-temperature and low-oxygen environment, and high-temperature smoke is generated; high-temperature smoke generated in the pyrolysis gas combustion chamber (3) and supplemented low-heating-value gas are mixed in a mixing chamber (4) on the top of the hot blast heater (1) so as to form low-dust and low-oxygen high-temperature smoke exhausted out of the hot blast heater (1). According to the hot blast heater recycling low-heating-value gas and the combustion method, the purpose of stable combustion of the ultra-low-heating-value gas is achieved, and the combustion of the hot blast heater is stable.