Fire-tube type waste heat boiler with three shells sharing noly steam pocket

The utility model relates to a fire pipe type residual heat boiler of which three boiler cylinders share one steam dome. The utility model comprises the boiler cylinders, the steam dome, lift pipes and drop pipes. The utility model is characterized in that the boiler cylinders which are connected in parallel share the steam dome and are respectively provided with one group of independent lift pipes and one group of independent drop pipes, and the lifting pipes and the drop pipes are connected with the steam dome; the front ends of the three boiler cylinders which are connected in parallel are connected with a share front smoke box, and the rear ends of the boiler cylinders which are connected in parallel are connected with a share rear smoke box. The utility model can reduce the diameters of the boiler cylinders, simplifies manufacturing technique, reduces manufacturing cost and has convenient installation and transportation.