The Moss hybrid boiler is a very versatile pressure vessel used with our coal fired combustion systems. Moss provides two (2) hybrid boiler designs: Conventional: sized from 150 - 800 HP and Traditional: sized from 900 - 1,500 HP (51,750 lbs./hr.). Each system has design pressures from 15 - 250 PSIG. The conventional systems radiant zone is located below the bottom of the HRT section of the boiler with the radiant tubes connected into the belly of the HRT section and sitting directly above the combustion zone. The traditional system has the radiant zone out front of the HRT firetube section with the combustion system located directly under the radian zone. The Moss systems are designed with large combustion zones, providing low furnace BTU heat releases that fires directly into the radiant zone of the boilers. Our three - pass design directs the flue gases through the boiler promoting excellent efficiency and quick response to swings in steam demand. Generally, the boiler pressure vessel incorporates a watertube membrane section in the radiant zone of the boiler and a two-pass HRT firetube pressure vessel in the convection zone.