Natural circulation waste heat boiler

The utility model discloses a natural circulation waste heat boiler, which is designed for solving the problems such as high energy consumption, high investment, high possibility of damage to equipment and the like of the existing forced circulation waste heat boiler. Front and rear evaporator outlets are connected with a steam drum through an ascending tube, and front and rear evaporator inlets are connected with the steam drum through a descending tube, therefore, a water circulation system is formed. Through adjusting the height between the steam drum and a rear evaporator, the natural circulation technology is adopted, the density difference between the ascending tube and the descending tube is used for pushing a medium to flow inside a whole system, no forced circulation pump is needed to serve as a power source, no electricity is consumed, the maintenance work is less, an adjusting mechanism is simple, the water circulation is safe and reliable, a boiler tube cooling effect is good, and the purposes of saving energy and investment and improving system safety can be achieved. The technology has important implications for safe and long-period running and stable operation of the boiler.