In an engine, a suitable support, a driving-shaft and a plurality of steam-cylinders mounted thereon, pistons in said cylinders, a centrally-arranged steam-supply conduit, a rotatable valve-sleeve mounted thereon, a stem connected therewith, a head on said stem, an angularly-di sposed rotatable member mounted in said head, means for connecting said pistons therewith, and connecting means between said rotatable member and said shaft.
In an engine, the combination of a plurality of cylinders, pistons moving therein, gyrating means for receiving the movement of the pistons, avalve-casing mounted centrally of the cylinders, the said casing being opened at one end, a hollow valve mounted in said casing and provided with controlling-ports, a pressure-delivering conduit projecting into one end of said valve, a shaft extending into the other end of said valve, and means for rotating the shaft in conjunction with the operation of the pistons for properly moving the valve to deliver the pressure successively to the different cylinders.
An engine comprising a plurality of cylinders, pistons mounted therein, a member connected with all of the said pistons for delivering their motion to other mechanism, a valve-casing having ports connected with the said cylinders, a valve mounted in the said casing, a shaft movably engaging the valve for rotating the same, means for imparting a rotary movement to the said shaft, means projecting into the valve for delivering the pressure to the engine and exterior means projecting inwardly and engaging the said valve for moving it longitudinally with respect to its shaft and the valve-casing for reversing the engine.
In testimony whereof I affix my signature in presence of two witnesses. USA en. USREE en. The biggest increase in turbine size has been in the field of electric-power generation, and the end of this evolutionary trend is not in sight. For purposes of comparing electric-power turbines and marine turbines, one kilowatt is about 1. Our projections show that well before the end of the century single units of 2, megawatts will be required for the most efficient generation of power.
For propulsion of big ships and power generation, where large unit output and maximum efficiency are essential, the steam turbine is unchallenged. Diesel engines have a comparable efficiency but the largest units so far built are limited to about 30, kilowatts.
Gas turbines go up to , kilowatts, but their efficiency is somewhat lower. At the others end of the size range, steam is again being considered as a power medium for automobiles; it remains to be seen, however, whether turbines or piston units will be more successful.
The incentive is a reduction in air pollution. Nearly complete combustion can be achieved when fuel is used to fire a boiler instead of being burned in the cylinder of an engine. Present-day applications of land-based steam turbines are by no means limited to electric power production.
In many industrial plants, such as refineries, sugar mills, paper mills and chemical plants, low-pressure steam is needed in large quantities for process purposes. Instead of producing this steam directly a low pressure boiler it is advantageous to install a high-pressure boiler at little extra cost and to drop the steam to the desired level by expanding it through a "back pressure" turbine whose outlet pressure corresponds to the pressure needed for process steam.
If steam at two pressures is desired, a second turbine can be installed ahead of the back-pressure turbine so that steam can be withdrawn between the two units as well as after the second. When this is done, electric power can be produced as a by-product at almost no cost. In most cases, of course, an external power supply is needed to handle fluctuating electric loads. It is also common in industry to use steam turbines as a direct power source for rotating machinery, such as compressors, blowers and pumps.
All told, the worldwide demand for steam turbines requires the production of units whose annual combined output exceeds 50, megawatts, or 65 million horsepower. The development of practical steam engines occupied many minds in the 18th and 19th centuries. The fist successful steam engine had been introduced in by Thomas Savery.
It was a crude affair in which steam was condensed alternately in two chambers, creating a vacuum that could be used to draw water from mines. In Thomas Newcomen built the fist practical steam engine with a piston. In James Watt began making his contributions, and in he was the first to patent methods for converting the reciprocating motion of a piston steam engine to rotary motion.
With this advance the steam engine finally became a versatile prime mover. By Richard Trevithick had built the first steam-driven locomotive. During the remainder of the 19th century piston steam engines were steadily improved many inventors; however, saw the advantages that would result if steam could be used directly to produce rotary motion by means of some kind of turbine. Many devices were built in crude imitation of waterwheels. It remained for Parsons to recognize that what was needed was a device with many rows of buckets in which a small amount of the steam's kinetic energy would be extracted with high efficiency at each of many successive stages.
Whereas the piston steam engine exploited only the pressure and temperature of steam as it came from a boiler, the steam turbine used some of the pressure to create high-velocity jets, whose energy was then absorbed by the rotating blades. Early in the turbine's history two concepts of blade arrangement were developed, each with its champions. Parsons favored what became known as reaction blading. Some of his competitors adopted impulse blading [see Figs.
In the reaction turbine the fixed blades and the moving blades that constitute one stage are practically identical in design and function; each accounts for about half of the pressure drop that is converted to kinetic energy in the entire stage.
In the fixed blades the pressure is harnessed to in- crease the velocity of the steam so that it slightly exceeds the velocity of the moving blades in the direction of rotation. In the moving blades the pressure drop is again used to accelerate the steam but at the same time to turn it around with respect to the blades , so that its absolute tangential velocity is almost zero as it enters the next bank of stationary blades.
Thus thrust is impart- ed to the moving blades as the steam's absolute tangential velocity is reduced from slightly above blade speed to approximately zero. An imaginary observer moving with the steam could not tell whether he was passing through the fixed blades or the moving ones. As he approached either type of blade it would appear to be nearly motionless, but as he traveled in the channel between blades his velocity would increase steadily until he reached their trailing edges, which would then seem to be receding rapidly.
In the impulse turbine the fixed blades are quite different in shape from the moving ones because their job is to accelerate the steam until its velocity in the direction of rotation is about twice that of the moving blades. The moving blades are designed to absorb this impulse and to transfer it to the rotor in the form of kinetic energy.
In this arrangement most of the pressure drop in each complete stage takes place in the fixed blades; the pressure drop through the moving blades is only sufficient to maintain the forward flow of steam. The amount of energy transferred to the rotor in each stage is proportional to the change in absolute steam velocity in the direction of rotation. It turns out that the value is about twice as high for impulse blading as it is for reaction blading. This means, in turn, that an impulse turbine will need fewer stages for the same power output than a reaction turbine; the efficiency, however, will be about the same for both types.
This being the case, one would expect impulse blading to have carried the day. Not so. As often happens in engineering, a design that seems clearly superior can present secondary problems of such magnitude that the choice between the alternatives becomes very nearly equal. In turbine design one of the major secondary problems is providing seals to keep the steam from leaking through the narrow spaces between the rotor and the stator.
In impulse blading the complete expansion in each stage takes place in the fixed blades. It is thus desirable to place the seals on as small a diameter as possible. This has led to a turbine design known as the diaphragm type [see Fig 8]. Because the pressure differential is large the diaphragm needs considerable space in the axial direction.
Therefore the width of the fixed blade must be made larger than it would otherwise have to be. A circumferential shroud is often placed around each ring of moving blades. In reaction blading the pressure drop per stage is less than it is in impulse blading; moreover, it is divided equally between fixed and moving blades. Thus both blades can be fitted with similar seals, and the seals need not be as effective as those needed on the fixed blades in impulse blading.
The result is a drum turbine [see Fig 9]. For more than 50 years these two kinds of turbine, the diaphragm turbine and the drum turbine, have been in competition without either type's demonstrating a distinctive advantage. Along the way the advocates of the two designs have moved somewhat away from pure reaction or pure impulse blading to adopt various compromise arrangements.
The assumptions on which the calculations are based are detailed together with the basis for the calculation of the steam properties required. On the disk accompanying the report, there are examples of calculations for simple and compound engines of the uniflow type and a file containing the information for calculating steam properties. Excerpt from Mechanism of Steam Engines This book is intended as an elementary treatise on the kinematics of reciprocating steam engines and steam turbines.
Sufficient attention is given to the behavior of the steam itself to enable the student to study intelligently the machine for which the steam is the source of power. Very well detailed metric plans in French.
The description is in German and the plans in Metric. Plans include a boiler. This requires castings. The plans are in French and are Metric. The plans are Metric and in German. Steam Harley anyone? Bett Oscillating Engine: A small oscillating engine designed by Bett as a simple demonstrator.
Compound Condensing Engine: A complex but efficient design from capable of being built by an advanced amateur. Danpf Engine: A good sized vertical engine. Elbow Engine: An unusual demonstrator engine that takes some skills to build but the results should be stunning. Elmer Verberg's Beam Engine: Elmer's Beam is a typical old fashioned beam style engine - the iconic steam engine, easy to build and impressive when running.
Elmer Verberg's Geared Engine: Elmer's Geared engine is an unusual design but once in use in the factories of the industrial revolution. Elmer Verberg's Horizontal Engine: Elmer's horizontal engine is a simple double-acting engine of the type comminly used in mills for grinding grain a hundred years or more ago.
Elmer Verberg's H-Twin Engine: Elmer's horizontal twin cylinder is mostly made of brass so is easy to machine and looks great.
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