Package boiler

A package boiler is a factory-made boiler. Package boilers are available in a range of standard designs. Package boilers are used for heating and act as a steam generator for small power purposes such as self-powered industrial plants. Package boilers are low pressure designs. A low pressure means low temperature water in the heat exchanger. The large difference between the flame temperature and the heat exchanger discards most of the available entropy. Discarding most of the entropy caps the thermodynamic efficiency below the range needed to make a low pressure boiler suitable for a co-generation plants even when the available capacity is adequate for the application. Advantages of package boilers are that they can be delivered and installed as a complete insulated assembly that doesn’t require a large exclusion zone around itself. The required steam, water, fuel, and electrical connections can be made rapidly. These boilers are inexpensive to operate because their automatic burner management system doesn’t require continuous supervision and they have low scheduled maintenance costs.^[1]

A great cost-saving for package boilers is their reduced need for draughting. In operation the stack gasses are cooler and less corrosive than solid fuels. They may be vented using an existing masonry chimney, or an insulated coaxial steel tube chimney. Because the burner’s blower delivers combustion air, the over-fire draught negative pressure required is nearly nil. Stack height need only be sufficient for structure safety and to clear the nuisance of the exhaust fumes. The tall chimney needed to provide a large negative pressure to draw combustion air through a bed of solid fuel is not required. In most installations a barometric damper is used to maintain a constant over-fire draught so that the air to fuel ratio remains constant instead of increasing with the increasing draught available at the stack as the outdoor temperature falls.