SZL series boiler includes SZL6-1.25/1.6-A II, SZL8-1.25/1.6-AII, SZL10-1.25/1.6-A II, SZL12-1.25/1.6-A II, SZL15-1.25/1.6-A II, SZL20-1.25/1.6-A II  so on. The series is double drum longitudinal boiler, chain grate as burning equipment. Coal dropping on grate from coal funnel is pushed into the furnace by grate to burn. The furnace arch apply Ultra-low long rear arch and front arch laid tie. The first two products are horizontal, three pass, water-fired tube combination boiler. Layout fire tube in drum. Water-cooling tube lay in the two sides of furnace. High temperature smoke enter into front smoke box through the second return from rear smoke box, then come back to rear smoke box through the third return ,  After flowing  into Economizer and precipitator, it will be exhausted to the air by introduced draft fan from Chimney; The last product is quickly package water tube boiler. Ontology is single Drum longitudinal A type. High temperature smoke entering into lower Convection Flue from both sides of the back of the combustion room flow into the front of stoker, then enter into up convection tube, after Convergence, passed through Economizer and precipitator, exhausted out into the air from chimney. The series boiler has much advantage: 1. the adaptability of combustion fuel is large, (adapt all kinds of Bituminous, anthracite, lignite and lean coal) 2. High thermal efficiency, low noise, small volume, less emission of smoking and dust.  3. Easy maintenance and overall installation. 4. Mechanized operation reduces the labor intensity of stoker worker.