Physics at Hamer Pellet Fuel

This morning we visited Hamer Pellet Fuel in Elkins, West Virginia.  This facility solely produces wood pellets common for wood pellet stoves.  This was an excellent opportunity to see several of the physics concepts we examine in application.

Let's begin by examining the blue cylinder seen in the picture section which turns and helps dry the saw dust used in the making process.  Our guide informed us the drum cylnder weighs approximately 110,000 lbs.  The estimated radius of the cylinder is 20 ft.  If the cylinder has an angular speed of 1.57 radians per second.  This speed must be maintained in order to complete the drying process.  The cylinder is rotated by four trunion wheels.  What total torque does the cylinder experience due to the rotating trunion wheels? This is an AP level question folks.  Remember to think of how we define torque.  The moment of inertia (I) for the cylinder is given by I = 1/2MR^2.

Now let us look at the dreaded incline plane. The picture section shows an incline with rollers used to move pallets loaded with bagged pellets at a weight of two thousand lbs.  With angle of the incline being rougly 15 degrees what is the final velocity of the pallet if it takes four seconds to move down the incline? The pallet is at rest initially.  The operators are using the incline, gravity, the pallets own mass and the rollers (eliminate friction) to move the pallet unassisted over a specific distance where the pallet is picked up by a forklift and deposited elsewhere. No man, no electical or computerized element are used.  Only a simple machine and physics.

Day One of Trip

Greetings folks!  Today was the first day of our excursion throughout West Virginia studying the timber and rail industries.  We spent the bulk of our time at Cathedral State Park. 

This is a remarkable sight which is in fact considered virgin timber; it has never had an ax brought against it.  Specifically, this area is predominantly composed of Hemlock.  Hemlock is an Evergreen tree that grows between 18 and 21 meters in height and makes its habitat in soils that are acidic; this is described as having a pH (Power of Hydrogen) below 7; alkaline describes a pH level above 7.  The numerical values can be determined by the equation pH = -log 10base [H+]. Qualitatively, pH canbe desribed as the molar concentration of hydrogen ions present.  The insturment typically used for this test consists of a a wire coated in silver chloride within a diluted hydrocloric acid solution surrounded by a glass membrane.  This membrane seperates the solution from what is being tested and determines the potential devoloped across the glass.  This can be shown to be proportional to the hydrogen ion concentration on the two surfaces.  Soil sample tests were conducted using a Vernier Labquest and were confirmed at a pH of roughly 4.1.

In addition to soil testing with pH confirmation, we worked in teams to determine the board feet of a tree.  Board feet is an industry term which estimates the amount of "usable" wood from a tree.  This proces includes using basic geometry and angle studies to determine the volume of a tree.  Volume is equal to area  times height.  We found the area by measuring the circumferene of the tree and used this to determine the radius.  With the radius known the area at chest level was determined.  A clinometer and the tangent function of the corresponding angle made and a distance of 66 feet from the tree were used to calculate the height.  The tree we measured was estimated at 1441 board feet.

This was a great first day.  Actually seeing a sight that had never been logged was exciting.  Yet, what struck me the most was the acid level of the soil and lack of life therein.  There really was not much living in this area aside from specific trees, mostly Hemlock, and ferns.  Cellular functions can only take within certain pH parameters and my best hypothesis is that a combination of reduced sun, a major canopy exists here, and acidic soil make this ecosystem limited in the number and types  of species it can sustain.

Take care, and I will bring you up to date on day two tomorrow.

Linear Expansion Follow -Up

Our last discussion entertained expansion of steel rails for a railroad due to the addition of heat.  So did our railroad engineer design the rail system correctly, or does this person need a refresher in physics?  Well, there was 2.5 millimeters between the rails.  Unfortunately, the linear expansion for the steel used was given at 1.2*10^-5 C^-1 and the original length of the rails were 12 meters long.  A 50 degree change in temperature could lead to linear expansion of .0072 meters or 7.2 millimeters; our engineer may have just cost his company quite a bit of money and should probably look forward to a physics refresher.

Thermodynamics, Railroading and Linear Expansion

My last post entertained briefly the First Law of Thermodynamics.  Such a concept permeates most all systems including what is often referred to as a closed system.  Within a closed system, matter can not cross a set boundary - enter or leave.  Most textbooks refer only to energy as being able to cross the set boundary within a closed system.  We demonstrated from earlier posts that work and energy were in fact synonomous, and as such, we can include work as being able to cross the set boundary of the system; this validates both th qualitative and quantitative definitions of the law: 1.  conservation of energy; 2.  delta U= Q-W - change in internal energy is equal to energy/heat added to the system minus the work done on the system.  Let's discuss why most solids expand when energy/heat is added.

As a child, I can remember my grandmother running hot water over the lids of jars to help open them.  This practice is based on the concept of linear expansion.  When energy/heat is added to most solids the molecules of the material speed up their interactions, push outward and the solid expands.  Quantitatively, and from a linear perspective, this is given by delta L = «a»L delta T - change in length is equal to the coefficient of linear expansion times the original length times the change in temperature. This «a» or coefficient of linear expansion will almost always be given in a stated problem.  For a good list of coefficients of this type you can go to www.engineeringtoolbox.com and search for coefficient of linear expansion for materials.  Here is a railroad example.

You are reviewing some specifications on a newly constructed railroad.  As you are examining the 12 meter long rails, you notice there is 2.5  millimeter gap between the rails. The coefficient of linear expansion for the steel used in the rail is 1.2*10^-5 C^-1; the units for coefficient of linear expansion are 1/C or C^-1. You check the almanac and find that the normal temperature can increase as much as 50 degrees Celsius on a hot day.  Did the chief engineer wisely design the rail system or should he retake high school physics?

Next time, we will.check the answer to this and tackle some other thermodynamic issues with rail transport.

www.engineeringtoolbox.com

Clearcutting Controversy

Here is a link to an interesting article from Clemson University which discusses the controversy surrounding clearcutting.  As with most pursuits of humankind, rarely if ever can we deal in absolutes.

http://www.clemson.edu/extfor/timber_production/fortp19.htm

Tree Identification

Tree identification will be an important part our project.  I have chosen to link  to a business named Industrial Timber and Lumber.  This group has several locations.  Yet, what pulled me to them was that they have two major sawmill operations in Vinton County, Ohio only about 45 minutes from my home, and a huge kiln drying operation in Marlington, WV.  I believe this is close to Elkins, WV.  I plan on visiting the sawmills
inthe next few days and hope we can stop at the Marlington location during our trip. 

Their site offers great deal of information on various species.  This includes tree identification by leaf, charted information about relative working properties for each wood, sample grade photos, and an overview of each species.  Incidently, information about each location's production offers some good insight into the productivity of our region. 

http://www.itlcorp.com/Species.aspx

First Law of Thermodynamics and Steam Locomotives

Recently, we have discussed work and energy concepts.  Let us now build upon those concepts within a basic steam locomotive.

We know from previous posts that there is more than one way to define work.  I am going to now offer another definition.  Work equals force times distance - W=Fd, is our most common definition. We also know this is equal to a change in energy.  Yet, if we consider pressure is equal to force divided by area - P=F/A, a common concept learned at least by middle school.  An easy manipulation tells us that F=PA.  Substituting this into our equation yields work equals pressure times area times distance - W=PAd.  But, area times distance is a definition of volume.  So work is equal to pressure times a change in volume - W=PdeltaV.  This concept of changing volume at constant pressure to move a piston is precisely the mechanism behind basic steam locomotive operation and owes its origination to the 1st Law of Thermodynamics;  the change in the internal energy of a system is equal to the heat added to a system minus the work done on the system - delta U=Q- W.

Our locomotive burns coal or oil to heat water. The water eventually changes to high pressure steam which increases its volume and expands pushing a piston within a cylnder.  This explains why locomotives must take on water periodically as its water supply is constantly be turned to steam.  The piston is connected to a rod apparatus which connects to coupling rods which move the wheels.  Incidently, the steam exaust is simply released by a valve under great pressure which accounts for the "choo choo choo choo" we hear and, the piston returns to its original position ready to be pushed again by pressure and volume expansion.

We now should begin to recognize some basic relationships among work, energy, power, and force with a locomotive.