Technical Description

The Steam Engine

Miguel Infante

The City College of New York

3/19/20

 

 

 

Contents        

 

Physical Shape and History_______________________________________________________

The Steam Engine

General Structure

Components___________________________________________________________________

The Firebox

Heat Rods and the Water Tank

Steam Pipe and Steam Chambers

Slide Valve, Drive Piston, Piston Rod, and Valve Rod

How it Works__________________________________________________________________

The Engine Process

Steam Engine Mechanisms

______________________________________________________________________________

Conclusion

 

 

 

The Steam Engine

 

Simple steam engine with flywheel attached.

https://www.livescience.com/44186-who-invented-the-steam-engine.html

Over the course of human history, human labor has become more and more mechanized allowing for heavier and faster work to be done. One outstanding invention that has accelerated the advancement of the human race is the steam engine. It was engineered by Thomas Savery and Edward Somerset around the year 1698. Its main function was to draw out water from a mine by using steam to perform mechanical pumping (Woodford 2019). The steam engine uses flammable fuel in order to boil water so steam can be produced to which it then creates pressure in order to move a series of components for mechanical work. Throughout the steam engine’s history, there have been different variations of how it is built and they range in size and the number of components. This technical description targets a generalized and simplified outline for the processes and mechanisms of a steam engine.

General Structure

The steam engine is made up of several components. The firebox, chimney, heat rods, a water tank, a steam pipe, a steam chamber, a slide valve, a drive piston, piston rod, and a valve piston. The firebox is a closed chamber system that has several heat rods extended from it. The heat rods lead to a separate component – the water tank. In it, the heat rods are suspended in the tank. Connected to the water tank is a steam pipe that leads into a steam chamber. Inside the steam chamber is a piston and valve mechanism that has rods extending outwards. Those rods are a part of a feedback system in the motion of the slide valve and the drive piston. A piston rod is connected to a valve piston that controls these said motions. The drive piston can be connected to whatever mechanism is used – for instance, train wheels, a conveyer belt, or a pump. As said earlier, steam engines come in different sizes so specific dimensions cannot be mentioned in this technical description.

General layout of a steam engine. Original Content – drawn by Miguel I

The Firebox and Chimney

The firebox, also known as a furnace, is an enclosed chamber where fuel is burned to create a fire for heat energy. Fireboxes are mainly cubic structures with a grilled hatch door to contain a fire whilst allowing oxygen to aid in the combustion process of fuel. In the top section of the firebox is a cylindrical piece referred to as the chimney that allows combustion products like carbon dioxide to move out of the firebox for continuous fuel burning. Chimneys are hollow, tubular structures involved in the exhaust of a system.

Heat Rods and the Water Tank

A water tank is any storage unit for water that comes in different volumes. Heat rods are primarily metal rods that allow the transfer of heat energy through conduction. The heat rods are connected to the firebox in a circular pattern. They then extend into the water tank but do not connect to the walls of a water tank to allow full heating of the water stored in the tank.

Steam Pipe and Steam Chambers

A steam pipe is any metal pipe that allows whatever pressure of steam to travel through it.  The steam pipe is connected to both the water tank and the steam chamber. A steam chamber is a contained compartment that captures steam. The steam chamber consists of two compartments in different sizes. These two compartments are connected by two small valve cylinders. The upper part of the steam chamber is smaller compared to the lower half. The lower half of the steam chamber is in the shape of a cylinder to accommodate the drive piston.

Slide Valve, Drive Piston, Piston Rod, and Valve Rod

A slide valve is a rectilinear component used to regulate the flow of an input to a system. A drive piston is a linearly reciprocating cylindrical component of a mechanism that aids in any major movement to it. A piston rod is a metal rod joining two components together creating a feedback system in movement. A valve rod is an extension that connects the valve to other components. The slide valve is a flat, rectangular, metal piece connected to a valve rod placed on top of the inlets separating the two compartments of the steam chamber. It is held in place by geometrical confinement which only allows it to move horizontally. The drive piston is located in the lower compartment of a steam chamber. Connected to the opposite sections of the drive piston and the valve rod is the piston rod.

The Engine Process

The process that drives the mechanism of the steam engine is fairly simple to understand. Water is boiled by heat in order to create pressure from steam that drives a piston forward and backwards. The source of the heat energy in the steam engine comes from the fire box. Coal, wood, or whatever flammable fuel source creates the heat energy from combustion. The carbon dioxide that is produced from the burning of fuel travels out from the chimney allowing oxygen to come into the firebox. The heat energy travels through the heat rods via conduction and boils the water in the water tank. Steam is generated as a result. The steam is then funneled into a steam pipe that leads into the steam chamber containing the drive piston and slide valve. As a result of the steam pressure rising, the slide valve opens an inlet to let the steam travel into one side of the drive piston chamber. The closed inlet allows for steam to escape allowing for a low-pressure area on the other side of the drive piston. The high pressure causes the drive piston to move outwards in order to produce mechanical motion for whatever mechanism it’s supporting. As the drive piston moves out, one end of the piston rod moves with it while the other end moves the opposite direction. This causes the valve piston to move the slide valve into another position which closes off high pressure going into one side of the drive piston. The low-pressure side of the drive piston is then filled with high pressure which forces the piston to move inwards. The outwards and inwards motion repeats the mechanism involving the piston rod, valve piston, and slide valve to move high pressure steam into the low-pressure side of the steam chamber.

Steam chamber/piston setup and colored pressure flow. http://ecampus.matc.edu/mihalj/scitech/unit5/engines/engines.htm

Steam Engine Mechanisms

By popular iconography, the steam engine is most seen in rotating the wheels of a locomotive. In this scenario, the drive piston is connected to a crankshaft that translates its linear motion into circular motion to turn a train’s wheels.

Cross section of steam engine powered locomotive.

http://www.stuartmcmillen.com/blog/making-of-peak-oil-6-artistic-decisions/

The original use of the steam engine was a pump system. The drive piston would be connected to a lever system that reciprocates a pump up and down to draw water out of a mine. Instead of a slide valve being used to release steam pressure for linear motion, a valve at its bottom would open as the piston creates suction by moving up and releasing water. The pressurized steam would condense and drive the piston down, closing the water valve and opening chamber to new steam.

Original steam engine pump setup.

 https://etc.usf.edu/clipart/15500/15597/steamengine_15597.htm

Conclusion

 The process behind a steam engine has been used for a wide spectrum of mechanical activities. Whether it be to drive a locomotive forward or take water out from a source, the steam engine can be built to drive whatever mechanism it has to. Using a heat source to generate steam from boiling water, it can move a mechanism of pistons to create work. The power and work in its output has advanced the mechanization of human labor. The steam engine has even evolved into more advanced forms like gas turbines and piston engines, improving the energy and fuel ratios. It is even still in use today by factories using steam engines to move their work lines forward.  The steam engine has been a technological marvel since it’s creation in 1698 by Savery and Somerset.

 

 

References

 

Whitney, W. D. (n.d.). Steam Engine. Retrieved March 17, 2020, from https://etc.usf.edu/clipart/15500/15597/steamengine_15597.htm

 

The making of Peak Oil comic #6: deliberate artistic decisions. (2017, May 16). Retrieved March 17, 2020, from http://www.stuartmcmillen.com/blog/making-of-peak-oil-6-artistic-decisions/

 

Mihal, J. (2016). Heat Engines. Retrieved March 17, 2020, from http://ecampus.matc.edu/mihalj/scitech/unit5/engines/engines.htm

 

Woodford, C. (2019, July 25). How do steam engines work?: Who invented steam engines? Retrieved March 17, 2020, from https://www.explainthatstuff.com/steamengines.html