Discrete Particle

Discrete Particle

ABMA

White Paper
Boiler Horsepower: History of Definitions in the Firetube Boiler Industry

American Boiler Manufacturers Association 8221 Old Courthouse Road – Suite 207 Vienna, VA 22182

Table of Contents
Section 1 2 3 4 5 Introduction Historical Background Basic Design Requirements Today’s Environment Considerations for the Future Description Page No. 3 3 5 5 6

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1. Introduction The purpose of this paper is to discuss developments over the past 50 years in the design of firetube boilers, as they relate to reductions in the boiler heating surface per Boiler Horsepower (Bhp). It is emphasized that only firetube boilers are discussed and that parallels should not automatically be drawn to transfer this logic to the design of other types of boilers which are not the topic of this paper. 2. Historical Background The concept of generating steam has been known since the first century A.D., when Hero of Alexandria described a boiler and reaction turbine. It was not until the 17th Century, however, that there is any recorded practical use of steam. At that time the events of the Industrial Revolution, primarily in England, promoted the more rapid development of the steam engine by such inventors as Thomas Newcomen and James Watt. James Watt is credited with being the first inventor to separate the steam engine and the boiler into two separate units in the latter part of the 18th Century. In these early times the primary use of the boiler was to generate steam for steam engines. As steam engines replaced the horse as a means of motive power, it followed that steam engines were rated in Horsepower. Boiler design progressed from what was essentially a kettle to a relatively largediameter flue pipe submerged in water – the first firetube boiler. As power and pressure requirements increased, boilers became larger and the single-flue pipe became a larger number of smaller diameter flue tubes combined with either an external or an internal furnace for the...