Posts Tagged ‘efficiency’

Uncontrollable Factors In Coal Fired Power Plants

Wednesday, September 5th, 2018

    You know that little red guy that bobs in and out of a glass of water, seemingly without end?   He’s an example of a non-perpetual motion device, because even he will eventually come to a stop due to something known as uncontrollable factors.   Uncontrollable factors are a hindering factor in coal fired power plants, as well, most notably by a measure of efficiency known as heat rate.

Uncontrollable Factors At Play

Uncontrollable Factors At Play

    The term heat rate is industry jargon for gauging how efficiently a coal fired power plant is operating.   We previously learned that heat rate can be affected by things like missing thermal insulation on pipes and equipment.   Of course missing insulation can easily be corrected because it’s directly under human control, but heat rate can be affected by many factors we can’t do anything about, known as uncontrollable factors.

    Human fallibility is behind the phenomenon of uncontrollable factors, and because we are less than 100% accurate and efficient, so is anything that we make.   At their best utility coal fired power plants have an overall efficiency of between 30 and 40 percent, which means 60 to 70 percent of the stored energy inside coal is wasted and doesn’t go towards generating electricity.

    Unfortunately there’s nothing we can do to eliminate these waste factors until improvements are made in the present level of technology. When we look through a microscope to view microbes we’re limited by the accuracy of the equipment, and in a similar way we are limited in everything we do as humans by the equipment we’ve built.   That includes energy efficiency within power plants.

    We’ll start identifying the uncontrollable factors that affect power plant performance next time.

Copyright 2018 – Philip J. O’Keefe, PE

Engineering Expert Witness Blog



Reciprocating Engines Maximize Efficiency When They Employ Flywheels

Thursday, December 21st, 2017

   Last time we had a look inside a marvelous piece of engineering machinery known as a crankshaft.   It plays a key role in converting the reciprocating linear motion of a steam driven engine into the rotary motion required to power externally mounted devices that are attached to it.   Today we’ll finish up our blog series on flywheels when we see how using one in conjunction with a crankshaft facilitates a more even transmission of energy.   Reciprocating engines maximize efficiency when they employ flywheels.

   We learned that the energy in the steam supply decreases as the piston moves in its cylinder, which means a concurrent decrease in the engine’s horsepower and its ability to power machinery.   Without an intervening action, the reciprocating steam engine would stall.   Now, let’s see how adding a flywheel to the crankshaft can solve the problem.

Reciprocating Engines Maximize Efficiency When They Employ Flywheels

Reciprocating Engines Maximize Efficiency When They Employ Flywheels


   As we’ve learned before, a flywheel stores up kinetic energy while the engine powering it is performing at full horsepower, but if that power should drop off or cease to be produced, the flywheel gives up the kinetic energy stored inside it so as to keep externally mounted machinery operating until that stored energy is exhausted.   This is all made possible because flywheels are designed to have moments of inertia sufficient to positively contribute to its storage of kinetic energy.   This inertia is a numerical representation of the flywheel’s resistance to change in motion.   Please review our past blog on the subject to refresh your memory.

   The overall effect is that while the engine is operating, there’s an even flow of energy between the engine and flywheel and horsepower is supplied to keep machinery mounted to the crankshaft operating.   Any diminishment in the power supplied will be compensated for by the flywheel’s stored kinetic energy.

   Next time we’ll introduce a new topic, a phenomenon known as cavitation.

opyright 2017 – Philip J. O’Keefe, PE

Engineering Expert Witness Blog



Superheating, Part I

Monday, August 19th, 2013

      Last time we learned that our power plant boiler as presently designed doesn’t do a good job of producing ample amounts of superheated steam, the kind of steam that turbines need to spin and power generators.   During the process of superheating the more heat energy that’s added to the steam in our boiler, the higher its temperature becomes.   However, our boiler can only produce a limited amount of superheated steam as it stands now.

Engineering expert witness power plant

      So how do we get more heat energy into the superheated steam?   Take a look at the illustration below for the solution to the problem.

coal fired power plant expert witness

      You’ll note a prominent new addition to our illustration.   It’s called a superheater.

      The superheater performs the function of raising the temperature of the steam produced in our boiler to the incredibly high temperatures required to run steam turbines and electrical generators down the line, as explained in my blog on steam turbines.   The superheater adds more heat energy to the steam than the boiler can alone.

      In fact, the amount of heat energy in the superheated steam produced with our new design is proportional to the amount of electrical energy that power plant generators produce.   Its addition to our setup will result in more energy supplied to the turbine, which in turn spins the generator.   The result is more electricity for consumers to use and a more efficiently operating power plant.

      But inefficiency isn’t the only problem addressed by the superheater.   We’ll see what else it can do next week.