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Dave steam 5 (savery)(35)

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History of steam engines, part 5 - Thomas Savery's steam-driven pump

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Dave steam 5 (savery)(35)

  1. 1. Steam Engines<br />A series of lessons <br />by David C<br />Dec 2010<br />
  2. 2. Part 5<br />Steam pumps<br />
  3. 3. Okay. Let’s start out where we left off in the last lesson:<br /> - A very deep mine that’s filling up with water. <br />
  4. 4. Okay. Let’s start out where we left off in the last lesson:<br /> - A very deep mine that’s filling up with water. <br />This could be rainwater coming down through the passage but in most cases it’s going to be groundwater oozing down through the rocks.<br />This is especially bad for mines near the sea.<br />
  5. 5. Well this is one way of doing it:<br />You stick a thing that looks like a syringe into the water and lift it up as high as it will go and let the water pour out through a hole near the top.<br />
  6. 6. Well this is one way of doing it:<br />All you need is someone strong enough to lift the handle, over and over and over and over ….. <br />
  7. 7. Well this is one way of doing it:<br />All you need is someone strong enough to lift the handle, over and over and over and over ….. <br />You can imagine it gets pretty tedious after a while, not to mention hard work.<br />
  8. 8. Here’s a picture from the 1500s, showing some improvements. <br />Can you se the crank handle on the left? You get some strong men to turn this handle.<br />
  9. 9. Here’s a picture from the 1500s, showing some improvements. <br />Can you se the crank handle on the left? You get some strong men to turn this handle.<br />That turns the wheel at the top, which raises and lowers the handle for three pumps at different levels.<br />Each pump feeds water up to the level above it.<br />
  10. 10. But look at this! <br />A radically new idea by Edward Somerset in Worcester, England in the 1650s.<br />
  11. 11. Water in a sealed container at the bottom gets boiled, which then pushes its way as steam into the two chambers on the side. <br />
  12. 12. Water in a sealed container at the bottom gets boiled, which then pushes its way as steam into the two chambers on the side. <br />The steam presses down on the water that happens to be there and forces it up the pipe to the top. <br />
  13. 13. Water in a sealed container at the bottom gets boiled, which then pushes its way as steam into the two chambers on the side. <br />The steam presses down on the water that happens to be there and forces it up the pipe to the top. <br />When the steam has done all it can, more water is poured into the chamber and the cycle starts over again.<br />
  14. 14. Mr Somerset built one into his home (Raglan Castle) and got it to work.<br />But he died before he could sell the idea to anyone in the mining business.<br />
  15. 15. The idea was picked up 50 years later by a fellow named Thomas Savery. <br />
  16. 16. The idea was picked up 50 years later by a fellow named Thomas Savery. <br />You can see that he’s improved on the design somewhat by adding a second chamber in the middle.<br />
  17. 17. The idea was picked up 50 years later by a fellow named Thomas Savery. <br />You can see that he’s improved on the design somewhat by adding a second chamber in the middle.<br />Steam flows from the boiler into this chamber, and then the valve behind it is closed.<br />
  18. 18. Now here’s the clever bit: <br />Savery pours water over the top of the chamber, which cools it down so that the steam inside it will condense.<br />
  19. 19. Remember that water occupies only 1/1600th the volume of the steam it was condensed from?<br />That means there’s an awful lot of nothing in that chamber now; a near-perfect vacuum.<br />
  20. 20. So now if you open the valve on the bottom left, water will be sucked up the pipe and into the middle chamber.<br />
  21. 21. And then if you close the lower valve to stop the water draining back to the bottom… <br />and open the valve to the pipe going upwards…<br />and then let the steam back into the middle chamber. It will push all that water up to near the top. <br />
  22. 22. So now you switch all the valves again and suck some more water into the middle chamber…<br />
  23. 23. So now you switch all the valves again and suck some more water into the middle chamber…<br />From here on you just repeat the cycle over and over, to get water out of the puddle at the bottom.<br />
  24. 24. What makes Savery’s pump work so well is that he is condensing the steam to suck water into the chamber.<br />
  25. 25. What makes Savery’s pump work so well is that he is condensing the steam to suck water into the chamber.<br />Condensing the steam creates a massive difference in volume which means you have a very powerful vacuum inside the chamber to do work with.<br />
  26. 26. What makes Savery’s pump work so well is that he is condensing the steam to suck water into the chamber.<br />Condensing the steam creates a massive difference in volume which means you have a very powerful vacuum inside the chamber to do work with.<br />Consequently this is a much more powerful device than the one Somerset invented.<br />
  27. 27. So MrSavery went into business manufacturing and selling these pumps to mining companies. <br />Some companies were rich enough and adventurous enough to try out the new idea. <br />
  28. 28. But as good as the idea looks on paper, the pumps turned out not to be very practical.<br />
  29. 29. But as good as the idea looks on paper, the pumps turned out not to be very practical.<br />Part of the reason is that you have to get a man to stand next to these tanks and pipes and open and close those valves at just the right time, over and over.<br />
  30. 30. But more importantly, it was an engineer’s nightmare trying to install one of these things halfway down a mine shaft. <br />Lighting a fire inside a coal mine, for example, is just asking for trouble.<br />
  31. 31. MrSavery did reasonably well out of his invention, though. <br />I guess his biggest contribution to the story is that he got people thinking about the usefulness of steam.<br />
  32. 32. Within a few years, another Englishman came up with an even better idea for using steam.<br />
  33. 33. Within a few years, another Englishman came up with an even better idea for using steam…<br />… inspired in part by this invention:<br />A pressure cooker designed to improve the quality of food.<br />
  34. 34. Within a few years, another Englishman came up with an even better idea for using steam…<br />… inspired in part by this invention:<br />A pressure cooker designed to improve the quality of food.<br />I’ll talk about that in my next lesson.<br />
  35. 35. End<br />dtcoulson@gmail.com<br />

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