The DZH type boiler is a horizontal three-return water-fire tube type boiler. A row of water-cooled wall tubes are arranged on the left and right sides of the furnace, and two sets of tube bundles are arranged in the drum to form two return paths. The boiler has sufficient heating surface and is equipped with a tail heating surface economizer. It is equipped with drums and induced draft fans for mechanical ventilation. Layered combustion. The coal has wide adaptability and good smoke elimination effect. The medium-resistance high-efficiency cyclone dust collector is equipped with the dust emission concentration reaching the environmental protection requirements of the second-class area. The flue gas passes through the upper combustion chamber of the rear arch, and the combustion chamber passes upwards, and the shed tube smoke chamber enters the first tube bundle to the front cigarette box, and then the front cigarette box is folded into the second bundle to the rear smoke box, and is drawn into the smoke through the induced draft fan. Roads, dust collectors and chimneys are finally discharged to the atmosphere. The boiler has high automation level, automatic adjustment of boiler feed water, high and low water level alarm, low water level interlock protection, and interlocking protection of lead and blower. Auxiliary auxiliary equipment is complete.