■ Coal-water mixture fired steam/hot water boiler is the new-generation environmental-protection product. It features Iow fuel cost and less contamination emission. Therefore it is the ideal substitution of oil and coal boiler.                                                                              ■ It is the free-circulation, inside combustion, water tube steam boiler that makes the combustion at little negative pressure and balanced ventilation. There are two boiler cylinders at the upper and lower levels longitudinally. Burner is mounted on the front wall and coal-water slurry fires sufficiently in the hearth (combustion efficiency >98%).                                                                                                 ■ Generated hot fume flushes the convection tube bank adversely via the hearth outlet. Heat of hot fume is exchanged in the air pre-heater at the rear of boiler.Then hot fume is treated with desulfurization dust collector and drained outside with chimney via the draught fan. ■ High combustion efficiency of coal-water slurry (>98%) and design heating efficiency (close to 90%). ■ Emission conforms to the environmental-protection requirements for Class I zone, Emission Standard of Boiler Contaminates. ■ Adopt the front stable-combustion hearth and reasonable section and volume so that boiler is applicable for various coal-water slurries and hearth is protected effectively against coking.