Coal-fired steam boiler adopts horizontal single drum chain grate structure, the boiler body is longitudinal arrangement of single drum, drum and water wall tube on both sides of the furnace radiation heating surface. The water pipe bundles on both sides of the boiler series are composed of the convection heating surface of the water pipe, and the threaded smoke pipe in the boiler drum is composed of the convection heating surface of the fire pipe. The tube plate shall be low stress arched tube plate without tension support. The coal fired boiler is composed of the upper body and the lower grate, and the economizer is arranged at the back of the boiler. The whole is in the form of quick installation, compact structure, small footprint, short installation period, less installation cost and less capital investment. The flue gas temperature of the tube plate of the steam boiler series is low, the single return tube plate of the tube is heated evenly, the low stress of the tube pla...