2. Secondly, the back box is lengthened, and three short coal-saving furnaces (with a diameter of less than 400 mm) are selected and fixed with frames.
3. Finally, a floor stand is added at the rear end of the trunk to facilitate entry and exit. On the other side of the trunk, the side plate is transformed into a reversible structure, and the side plate is widened for people to use. Repairing details as needed.