When sizing a boiler you must have enough capacity to handle the maximum hourly load of the system. You should always install a boiler with future expansion in mind. More than one may be required depending how critical it is for continuous service during shutdown and maintenance. All boilers should be equipped with fully automatic controls to provide adequate safety at all times. All equipment in the system should be rated at least to the maximum allowable working pressure. Equipment and controls should meet if not exceed ASME, UA, local, state and all applicable codes.
Boilers require fresh air and ventilation and must be installed in areas where both can be attained. When in confined rooms permanent openings for air transfer should be provided. Vents and draft creating equipment may be needed to achieve proper movement. The venting system should be wired to the boiler to assure proper air when the boiler is fired up. At least two doors at a minimum are recommended for ingress and egress to insure proper safety for personnel.
When boilers are not used for periods of time, such as seasonal or storage in freezing weather the system should be drained so not to damage the equipment.
Types of boilers
Boilers based on tubes:
- Fire Tube Boiler - an external heating source produces hot gas which is then passed throught tubes that run through a container or vessel. The heat from the tubes is transfered to the water contained in the vessel which intern creates steam.
- Water Tube Boiler - this is basically reversed from a fire tube boiler. Water passes throught tubes that run through a container or vessel which intern creates steam. Hot gas surrounds the tubes that is pumped into a vessel from an external source.
Boilers by fuel types:
Boiler water types:
- Hot water boiler - a pressure vessel, fired or unfired, used to heat water. They can be classified by: low pressure boiler, high pressure or temperature power boiler, or miniature boiler depending on the various codes.
- Steam boiler - a closed pressure vessel, fired or unfired, used to create steam by applying heat. They can be classified by: low pressure boiler, high pressure or power boiler, small power boiler or miniature boiler depending on the various codes.
- Water boiler - designed to heat supply water and has automatic controls to limit the temperature to a maximum of 210°.
- API RP 535 - Burners for Fired Heaters in General Refinery Services
- API RP 573 - Inspection of Fired Boilers and Heaters
- ISO 16528-1 - Boilers and pressure vessels -- Part 1: Performance requirements
- ISO 16528-2 - Boilers and pressure vessels -- Part 2: Procedures for fulfilling the requirements of ISO 16528-1