The Birth of The Water Tuber Boiler and Christened as Steam Generator

1. The Birth of The Water Tuber Boiler and Christened as Steam Generator P M V Subbarao Professor Mechanical Engineering Department

2. The Crisis As industry developed during 19th century, so the use of boilers for raising steam became widespread. Disastrous explosions sometimes occurred. Boilers of that period consisted of heated pressure vessels of large diameter. These are subject to internal pressure which is tensile stresses in the walls of the enclosure. The existence and importance of stress, known as �hoop stress� is given by

3. Historical Development 1766 William Blakey: Patent on water in tube and fire outside. Several tubes alternately inclined at opposite angles were arranged in the furnaces, the adjacent tube ends being connected by small pipes. The first successful user of water-tube boilers, however, was James Rumsey, an American inventor, celebrated for his early experiments in steam navigation, and it is he who may be truly classed as the originator of the water-tube boiler. In 1788 he patented, in England, several forms of boilers, some of which were of the water-tube type. One had a fire box with flat top and sides, with horizontal tubes across the fire box connecting the water spaces. Another had a cylindrical fire box surrounded by an annular water space and a coiled tube was placed within the box connecting at its two ends with the water space. This was the first of the "coil boilers". Another form in the same patent was the vertical tubular boiler, practically as made at the present time.

5. John Stevens, 1804 The first boiler made of a combination of small tubes, connected at one end to a reservoir, was the invention of another American, John Stevens, in 1804. This boiler was actually employed to generate steam for running a steamboat on the Hudson River, but like all the "porcupine� boilers, of which type it was the first, it did not have the elements of a continued success.

6. 1805 : John Cox Stevens Another form of water tube was patented in another form of water tube was patented in 1805 by John Cox Stevens, a son of John Stevens. This boiler consisted of twenty vertical tubes, 1� internal diameter and 40�� long, arranged in a circle, the outside diameter of which was approximately 12 inches, connecting a water chamber at the bottom with a steam chamber at the top. The steam and water chambers were annular spaces of small cross section and contained approximately 33 cubic inches.

7. Julius Griffith, in 1821 The first purely sectional water-tube boiler was built by Julius Griffith, in 1821. In this boiler, a number of horizontal water tubes were connected to vertical side pipes, the side pipes were connected to horizontal gathering pipes, and these latter in turn to a steam drum.

8. 1822, Jacob Perkins In 1822, Jacob Perkins constructed a flash boiler for carrying what was then considered a high pressure. A number of cast-iron bars having 1�� annular holes through them and connected at their outer ends by a series of bent pipes, outside of the furnace walls, were arranged in three tiers over the fire. The water was fed slowly to the upper tier by a force pump and steam in the superheated state was discharged to the lower tiers into a chamber from which it was taken to the engine.

9. Joseph Eve, 1825 The first sectional water-tube boiler, with a well-defined circulation, was built by Joseph Eve, in 1825. The sections were composed of small tubes with a slight double curve, but being practically vertical, fixed in horizontal headers, which headers were in turn connected to a steam space above and a water space below formed of larger pipes. The steam and water spaces were connected by outside pipes to secure a circulation of the water up through the sections and down through the external pipes.

10. John M'Curdy In the same year, John M'Curdy of New York, built a "Duplex Steam Generator" of "tubes of wrought or cast iron or other material" arranged in several horizontal rows, connected together alternately at the front and rear by return bends. In the tubes below the water line were placed interior circular vessels closed at the ends in order to expose a thin sheet of water to the action of the fire.

11. Stephen Wilcox, 1856 Stephen Wilcox, in 1856, was the first to use inclined water tubes connecting water spaces at the front and rear with a steam space above. Water-cooled enclosures.

12. Struggle for Understanding First Law of Steam Generation 1803 John Stevens: A pseudo-water-tube design used in a steamboat. 1822 Jacob Perkins: Once-through boiler using cast iron bars. 1856 Stephen Wilcox: Inclined tube boiler with water-cooled enclosures. 1880 Allan Stirling: Bent tube connecting drums.

13. The Theory of Producing Steam Water boils and evaporates at 100�C under atmospheric pressure. By higher pressure, water evaporates at higher temperature - e.g. a pressure of 10 bar equals an evaporation temperature of 184�C. During the evaporation process, pressure and temperature are constant, and a substantial amount of heat are use for bringing the water from liquid to vapour phase. When all the water is evaporated, the steam is called dry saturated. In this condition the steam contains a large amount of latent heat. This latent heat in the dry saturated steam can efficiently be utilised to different processes requiring heat. The steam boiler or steam generator is connected to the consumers through the steam and condensate piping. When the steam is provided to the consumers, it condensate. It can then be returned to the feed water tank.