Integral economizer steam generator

A bottom supported steam generator for burning a solid fuel comprising:

• a steam drum at an upper elevation;
• a water drum at a lower elevation;
• means for supporting said water drum from the ground;
• a plurality of front wall tubes forming a front wall, and a plurality of rear wall tubes forming a rear wall, said walls connecting said steam drum and water drum and forming a vertical gas pass, the front wall having an inlet opening at only the upper end for the ingress of gases and a rear wall having an outlet opening at only the lower end for the egress of gases;
• a furnace for the burning of fuel therein;
• steam generating tubes lining the walls of said furnace and connected to said steam drum;
• means for conducting combustion gases from said furnace to the inlet opening of said vertical gas pass;
• a plurality of vertical tubes arranged in a plurality of rows within said vertical gas pass, and connecting said steam drum with said water drum, and supporting said steam drum from said water drum;
• a plurality of horizontal economizer tubes forming an economizer bank and arranged in a plurality of rows, said economizer tubes each interspersed between said vetical tubes at elevations below the inlet opening and above the outlet opening;
• and means for conveying water from said economizer to said steam drum.