An O-type water tube boiler represents an alternate way of designing Water Tube Boilers. It is symmetrical, well balanced and very compact compared to D-type Boilers and A-type Boilers.

Capacities for O-type package units can go as high as 300,000 lbs/hr (135 tons/hr) with pressures up to 1750 psi (120 bar) and temperatures up to 1050 oF (565 oC). It is appropriate where space is limited. It can be Field-Erected, if required by site conditions or for size larger than 300,000 lbs/hr (135 tons/hr). It can fire any fuel but may be less appropriate to fire Heavy Fuel Oil than an A-type or D-type Boiler.

Solid fuels like wood wastes cannot be fired in the O-type furnace and if used have to be burned in separate combustion chamber. The boiler then is used as a waste heat recovery boiler.

Super-heaters are radiant and convective type and produce quite stable superheated steam temperatures over all firing range. That design can be built with membrane water walls or with tangent tubes. Furnace sizes are smaller than a D-type or an A-type and will result in higher heat release rates influencing NOx levels. They are also used as heat recovery steam generators. O-types are popular as portable boilers and boilers for rents. They are often use for cogeneration, petrochemical industries, industrial processes etc.

It is a well-balanced boiler design. O-type boilers are easier to ship by road or by train than D-type boilers because of the fact that their shape will ease the passage through.

The Aqua-tube Boiler is one of the Water tube Boilers that used where hot water or steam is required for heating or for the processes like dry cleaners, apartment, building etc., in institutional parts like schools, university campus, airports, hospitals and industrial plants like oil & gas, food industries, textiles, pulp & paper, wood processing,…etc. The Aquatube is also ideal for boiler replacement projects. The boiler may be provided pre-assembled ex-works and ready for start-up or delivered in modules and assembled on site using conventional boiler making techniques.