Water-fired tube boilers are drawn towards the furnace by pulling part of the riser tubes on the headers on both sides. Then it is introduced into the bottom of the drum side and supplemented by heat insulation at the bottom of the drum to form the heating surface of the furnace top. The horizontal three-return boiler successfully solves the problem that the bottom of the drum is directly irradiated by high-temperature flames with a novel furnace structure. Avoid “bulge” defects.

The setting of the two-wing flue of this series of steam boilers enables the flue gas to enter the front smoke box smoothly. Keep the previous tube sheet temperature the same to avoid tube sheet cracks due to temperature stress. The single-return threaded smoke pipe is used in the drum to enhance the heat transfer effect. At the same time, the threaded smoke pipe has the function of self-cleaning, which avoids the accumulation of dust in the smoke pipe. The front and rear arches of the 10t/h series boilers adopt an integral casting structure supported by water-cooled wall tubes to form arches. The rear arch is low and long, the exit section is reverse inclined, and the front arch inclination angle of 45° echoes the rear arch, forming an obvious inverted “α” flame, which is conducive to the combustion of inferior coal and has strong adaptability to coal types.

The design of the sealing structure on the grate side of the horizontal three-return boiler is advanced and reasonable. It avoids the defect that the side seal is stuck on the grate and the air distribution on both sides of the grate is uneven and the side seal is burned out. Boilers of 4t/h and below adopt the side-sealed cold-added angle iron rib structure. The boiler above 6t/h adopts the contact-type side-sealing and lower-sealing structure. DZL series horizontal boiler grate has an independent air chamber under the grate, and the air is fed from both sides. A new type of crank arm screw adjustment structure is adopted, so that the air-conditioning ventilation cross-section ratio can be adjusted flexibly and the air distribution is uniform. A push-pull gate ash cleaning device is designed, and the gate adopts heat-resistant cast iron finish machining and sealing structure. So as to effectively prevent secondary combustion deformation and grate air leakage.

The raw materials of this type of boiler products are widely distributed, and the processing technology is advanced. The biomass energy pellets are known as green coal, which is a kind of clean energy. As the fuel of the boiler, it has a long burning time, high temperature of the intensified combustion furnace, and is economical. At the same time, it does not pollute the environment. It can replace firewood, coal and natural gas. It is an environmentally friendly product with high efficiency and energy saving.

The combustion equipment and furnace structure of the horizontal three-return boiler are reasonably designed. Compatible with the designed fuel varieties to ensure safe, stable and efficient combustion. The heating surface of the water and fire tube boiler is reasonably arranged. Select a reasonable and economical flue gas flow rate to reduce the resistance on the flue gas side. Reasonably set access doors (holes) to facilitate cleaning, cleaning, maintenance and repair of the heated surface. When the convective heating surface is prone to ash accumulation, a ash cleaning device should be installed. Boiler doors (holes), peep holes, and slag outlets should be sealed to ensure that the boiler air leakage coefficient is within the design requirements.