The invention relates to a bidirectional environment-friendly energy saving boiler with three return strokes, which comprises a boiler body, an inner
water jacket and an outer
water jacket, wherein a heat collecting plate and a heat collecting tube are extended at the upper part of the inner
water jacket; a heat collecting tube is additionally installed in a bent
flue; and a dust falling chamber and a dust removing door are arranged at the lower part of a
flame outlet. In the invention,
combustion chambers of the bidirectional environment-friendly energy saving boiler with three return strokes comprise a reverse
combustion chamber and a secondary
combustion chamber, and a double-layer water tube grate is arranged below the reverse
combustion chamber, thereby having larger heat
absorption capacity and fastest
heat energy transmission. The invention has the advantages that the
flue with three return strokes is used, thus the
flue is lengthened in the boiler body so as to be convenient for heating the heat collecting plate and the heat collecting tube; and in addition, the
flame in the reverse
combustion chamber goes downwards from the gap of the first layer of the double-layer water tube grate, and the tongue of
flame directly goes to the second layer of the water tube grate, so the boiler has high heating speed and more heat utilization, saves
coal by more than 45%, and can burn industrial and household garbage. The boiler of the invention can be widely applied to large factories and mines, organizations, districts and hotels for heating and
bathing. Thus, the boiler of the invention is ideal equipment for meeting the current national requirements of energy saving and emission reduction.