ChᎬ 311 HW - Coal Mining in Scotland Last year, while on vacation, I visited the National Mining Museum in Scotland. It is a real coal mine that operated from

1895-1981, and now serves as a museum, with guided tours where people can visit various of the mine buildings and actually go down into the mine to learn about its operation and history. It was a fascinating experience, and one that stirred all kinds of engineering amazement and human thoughts in me. So I would like to share some of what I learned, and ask you to analyze various aspects of the process of coal mining. In this particular mine there is just one “lift” (i.e. elevator), consisting of a double-decker "cage" which was used to carry both the miners and the coal. The capacity of the cage is 60 men (no women were allowed, but boys as young as 10 could work there), who rode in it down to a depth of 1500 feet underground (how many New York City blocks is that? Remember that in NYC there are 20 blocks/mile. How long would it take you to walk that far? How tall is the Empire State Building?). Over the course of each day, the miners cut coal from the walls of tunnels they dug underground, emanating out from the lift shaft, and put it in carts that ran on rails back to the lift. The carts were brought to the surface, emptied, and sent back down for more coal. The cage, which is suspended from the end of a steel cable, was raised or lowered by a very large machine called the "winding," shown here https://www.youtube.com/watch?v=1sMHZW9Lquo In this machine the lift cable winds around a large-diameter shaft that is made to turn at a controlled rate using a steam engine. When the mine was active, the steam for the engine was generated by boiling water in boilers. Some photographs of these and other boilers are shown here: https://www.google.com/search?q=coal+furnace+lady+victoria&client=firefox-b-1- d&sxsrf=ALeKk01Po7s00H6SpGVNFOK- h9VxfsBxmQ:1617988040774&tbm=isch&source=iu&ictx=1&fir=jXHVdBC3H9hWaM%252CB- PwLeGQ6uH9vM%252C_&vet=1&usg=AI4_- kQISy_eqXc1jXKMR3jV5BmLzW2d0Q&sa=X&ved=2ahUKEwjg5K6T0_HvAhWHFVkFHTMOAswQ9QF 6BAgNEAE#imgrc=jXHVdBC3H9hWaM The heat for the boilers was generated by burning coal. Discussion and Analysis: 1 - Watch the video of the winding machine. The diameter of the shaft is about 4 feet. Estimate the time it took to raise or lower the cage 1500 feet. Now imagine you're in that cage. In the dark. Twice a day. With 59 other people. 2 Estimate: How much coal did each miner have to remove from the mine each day to ensure that a cage full of men could leave the mine at the end of a shift? How does this compare with his own weight? (I wonder if this is where the expression “pulling his weight” comes from?). Strategy: a) Visualize the system. There are many processes to this operation. Draw a schematic, showing each separate process unit, how they are all connected, and what the inputs and outputs are in terms of mass, energy, and work (please no numbers here yet!). Label all process units and define all variables, with units. b) Analyze. What goes on in each of the process units? Explain in words. Define “efficiency" for each of the process units, and list any factors you think will contribute to that efficiency being <1. c) Numbers. What quantitative information do you need in order to answer the question about the miners? What numbers are known? What numbers will you have to estimate? d) Follow-through. How much electricity is needed to keep the lights on in your house for 6 hours a day? Assuming your electric power comes from coal, how much coal does this require? NOTE - Each part of this problem requires knowledge of ChE processes as well as estimates of some numbers. I would like you to think through all this, and am not expecting an exact answer. However, you should be able to come up with a reasonable order of magnitude estimate for the answers. Some relevant links: The type of boiler used at this mine was the Lancashire boiler. You can read about its development here: https://en.wikipedia.org/wiki/Flued boiler