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Potable Water - The Third Way.
You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] Brian Whatcott Altus OK |
Potable Water - The Third Way.
Dear Brian Whatcott:
On Sep 21, 3:35 pm, Brian Whatcott wrote: You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] There are ship-board distiller units that use an engine to pull a vacuum, and the engine's waste heat to boil that water, to generate drinking water. A little shorter... David A. Smith |
Potable Water - The Third Way.
Brian Whatcott wrote in
: You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] Brian Whatcott Altus OK My deepest apologies to the engineers who may be rolling under their desks, crushing their pocket protectors. It took me a while to stop chortling. I nearly lost my Chinese dinner! Psst...Brian....40'? What about the lake above 40', it's 400' deep and above 40' ASL. It hasn't boiled away in millions of years from all that pressure and lack of pressure. In Tehran, Iran, my apartment was about 7000' ASL. Water DID boil at a lot lower temperature. Making a cake at 7000' altitude is simply amazing! ONE little cake mix makes 4 cakes!.....er, ah, after you clean out the oven from putting ALL the cake mix in the pan, filling the oven! But, alas, even at 7000', the water in my glass didn't boil itself at ambient temperature, even at 110F out on the lawn! Every engineering firm across the planet is going to be a jolly place after hearing about this on Monday...(c; Larry -- Sure glad it doesn't work that way! We'd all be DEAD! |
Potable Water - The Third Way.
dlzc wrote in news:1190415672.506271.93890
@k79g2000hse.googlegroups.com: There are ship-board distiller units that use an engine to pull a vacuum, and the engine's waste heat to boil that water, to generate drinking water. A little shorter... David A. Smith http://en.wikipedia.org/wiki/Boiling_point "The boiling point of water is 100 °C (212 °F) at standard pressure. On top of Mount Everest the pressure is about 260 mbar (26 kPa) so the boiling point of water is 69 °C. (156.2 °F)." AT 40' ASL, the boiling point must be down to...to....211.95F! Larry -- Search youtube for "Depleted Uranium" The ultimate dirty bomb...... |
Potable Water - The Third Way.
"Larry" wrote in message ... Brian Whatcott wrote in : You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] Brian Whatcott Altus OK My deepest apologies to the engineers who may be rolling under their desks, crushing their pocket protectors. It took me a while to stop chortling. I nearly lost my Chinese dinner! I think he is suggesting that the two tube be connected so that they form a vacuum at the top. It wouldn't take much to make the sal****er evaporate to fill the vacuum and condense over on the fresh water side. Productivity wouldn't be very high though. |
Potable Water - The Third Way.
Dear Larry:
"Larry" wrote in message ... dlzc wrote in news:1190415672.506271.93890 @k79g2000hse.googlegroups.com: There are ship-board distiller units that use an engine to pull a vacuum, and the engine's waste heat to boil that water, to generate drinking water. A little shorter... http://en.wikipedia.org/wiki/Boiling_point "The boiling point of water is 100 0C (212 0F) at standard pressure. On top of Mount Everest the pressure is about 260 mbar (26 kPa) so the boiling point of water is 69 0C. (156.2 0F)." AT 40' ASL, the boiling point must be down to...to....211.95F! What Brian left to the reader's imagination, is that the head space of the tubes is at a near perfect vacuum, flooded only with water vapor. You might recall that a perfect vacuum will lift a column of water about 32 feet, on a high pressure day. Or had you not figured that out? David A. Smith |
Potable Water - The Third Way.
On Sat, 22 Sep 2007 01:41:21 GMT, "Toller" wrote:
I think he is suggesting that the two tube be connected so that they form a vacuum at the top. It wouldn't take much to make the sal****er evaporate to fill the vacuum and condense over on the fresh water side. Precisely right. I'm surprised Larry didn't catch that. |
Potable Water - The Third Way.
In article ,
Larry wrote: Brian Whatcott wrote in : You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] Brian Whatcott Altus OK My deepest apologies to the engineers who may be rolling under their desks, crushing their pocket protectors. It took me a while to stop chortling. I nearly lost my Chinese dinner! Psst...Brian....40'? What about the lake above 40', it's 400' deep and above 40' ASL. It hasn't boiled away in millions of years from all that pressure and lack of pressure. Ummm...there is quite a difference between atmospheric pressure at 40' ASL and a (near) vacuum. Presumably the connection at the top is airtight and made with as little air as possible entering the tubes, and presumably also the bottoms of the tubes open and submerged in some sort of a vented container At sea level, atmospheric pressure will only support somewhere in the vicinity of 40 feet of water, so the top of the tubes will be approaching a vacuum. (This is why wells water wells deeper than 35 or so feet require a pump in the well, rather than at the top.) I see no reason why this wouldn't work, at least to some degree, although I do wonder how using a still of any sort differs from distillation. I also wonder how easy it would be to make an effective vertical solar collector on a boat that doesn't need constant climbing about to fiddle and adjust. -- Andrew Erickson "He is no fool who gives what he cannot keep to gain that which he cannot lose." -- Jim Elliot |
Potable Water - The Third Way.
On Sep 21, 10:15 pm, Andrew Erickson
wrote: In article , Larry wrote: Brian Whatcott wrote in : You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] Brian Whatcott Altus OK My deepest apologies to the engineers who may be rolling under their desks, crushing their pocket protectors. It took me a while to stop chortling. I nearly lost my Chinese dinner! Psst...Brian....40'? What about the lake above 40', it's 400' deep and above 40' ASL. It hasn't boiled away in millions of years from all that pressure and lack of pressure. Ummm...there is quite a difference between atmospheric pressure at 40' ASL and a (near) vacuum. Presumably the connection at the top is airtight and made with as little air as possible entering the tubes, and presumably also the bottoms of the tubes open and submerged in some sort of a vented container At sea level, atmospheric pressure will only support somewhere in the vicinity of 40 feet of water, so the top of the tubes will be approaching a vacuum. (This is why wells water wells deeper than 35 or so feet require a pump in the well, rather than at the top.) I see no reason why this wouldn't work, at least to some degree, although I do wonder how using a still of any sort differs from distillation. I also wonder how easy it would be to make an effective vertical solar collector on a boat that doesn't need constant climbing about to fiddle and adjust. -- Andrew Erickson "He is no fool who gives what he cannot keep to gain that which he cannot lose." -- Jim Elliot hmmm, I wonder what the rate would be? One could assume that you do not have to put in any heat to increase the temp so any heat input would simply go into latent heat of water vapor. You would hav o maybe use solar to heat the salt water side and cool the fresh water side by immersing it in the ocean. Then the max rate would simply be power in (whatever the heat from the sun would be in watts/m2 times the area of your collector) which is Joules/sec which is roughly 4 calories/sec. Somebody look up the latent heat of water (I dont have my handbook handy) and then you have grams/sec of fresh water (maximum rate). |
Potable Water - The Third Way.
On Sat, 22 Sep 2007 01:21:39 +0000, Larry wrote:
[Brian] The boiling point of water at the top of a sealed 40 ft column of water is near ambient. My deepest apologies to the engineers who may be rolling under their desks, crushing their pocket protectors. It took me a while to stop chortling. I nearly lost my Chinese dinner! ... Larry They say if you give a fool half a chance, he will rush in. And so he did. TWICE! Chortling, at that. Brian W |
Potable Water - The Third Way.
Brian Whatcott wrote:
On Sat, 22 Sep 2007 01:21:39 +0000, Larry wrote: [Brian] The boiling point of water at the top of a sealed 40 ft column of water is near ambient. My deepest apologies to the engineers who may be rolling under their desks, crushing their pocket protectors. It took me a while to stop chortling. I nearly lost my Chinese dinner! .. Larry They say if you give a fool half a chance, he will rush in. And so he did. TWICE! Chortling, at that. Brian W And your point was??? |
Potable Water - The Third Way.
On Sat, 22 Sep 2007 01:04:55 -0500, cavelamb himself
wrote: Brian Whatcott wrote: The boiling point of water at the top of a sealed 40 ft column of water is near ambient. They say if you give a fool half a chance, he will rush in. And so he did. TWICE! Chortling, at that. Brian W And your point was??? Put this pointy hat on, and go stand in the corner with that other fellow. I'll tell you when to sit down again. Brian W |
Potable Water - The Third Way.
"N:dlzc D:aol T:com (dlzc)" wrote: Dear Larry: "Larry" wrote in message ... dlzc wrote in news:1190415672.506271.93890 @k79g2000hse.googlegroups.com: There are ship-board distiller units that use an engine to pull a vacuum, and the engine's waste heat to boil that water, to generate drinking water. A little shorter... http://en.wikipedia.org/wiki/Boiling_point "The boiling point of water is 100 0C (212 0F) at standard pressure. On top of Mount Everest the pressure is about 260 mbar (26 kPa) so the boiling point of water is 69 0C. (156.2 0F)." AT 40' ASL, the boiling point must be down to...to....211.95F! What Brian left to the reader's imagination, is that the head space of the tubes is at a near perfect vacuum, flooded only with water vapor. You might recall that a perfect vacuum will lift a column of water about 32 feet, on a high pressure day. Or had you not figured that out? Well no, he obviously hadn't figured that out. Nor can anybody figure out what is going to hold a column of water 40 ft high as was stated in the original post. The tubes may be 40 feet but the column of water will be considerably less. How much less will depend on how much energy is heating on the hot side and how much energy is cooling on the cool side. The total amount of energy needed is not going to be any different than any other distilling method. Unless you have the free or cheap sources of cooling and heating at specific temperatures this isn't going to work any better either. -jim David A. Smith ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Potable Water - The Third Way.
On Sat, 22 Sep 2007 10:15:40 -0500, jim wrote:
What Brian left to the reader's imagination, is that the head space of the tubes is at a near perfect vacuum, flooded only with water vapor. You might recall that a perfect vacuum will lift a column of water about 32 feet, on a high pressure day. Or had you not figured that out? Well no, he obviously hadn't figured that out. Nor can anybody figure out what is going to hold a column of water 40 ft high as was stated in the original post. The tubes may be 40 feet but the column of water will be considerably less. How much less will depend on how much energy is heating on the hot side and how much energy is cooling on the cool side. The total amount of energy needed is not going to be any different than any other distilling method. Unless you have the free or cheap sources of cooling and heating at specific temperatures this isn't going to work any better either. -jim Well, at least this respondent Jim, is operating at shall we say the 7th grade level of science/engineering insight. Like so many other products of the domestic school system, he seems to have a severe case of self-esteem syndrome. Still, he may be retrievable, starting with a science demonstration he may have missed. Place a beaker of water in a bell-jar and pump the air out. When 99% of the air has been pumped out, the water in the beaker is boiling vigorously, until, in the usual way, the beaker boils dry. The beaker feels cool to the touch, naturally. To quote him: "unless I have a cheap source of heating this won't work..." For the $64 prize: NOW do you get it? Brian Whatcott Altus OK |
Potable Water - The Third Way.
Sounds neat, haven't seen that one before.
Thanks for sharing. "Roger Long" wrote in message ... There's another neat way you can demonstrate this with minimal equipment. Take a tight fitting jar and get the water boiling vigerously in it with the cap on loose enough to let the steam out. When it is full of dense steam and about 1/3 boiling water, remove instantly from heat and tighten cap. When everything is cooled to room temperature, put an ice cube against the jar and the water will start to boil. The ice condenses the water vapor further, reducing the pressure to the point where the water will boil at room temperature. I've seen it done and it looks like the ice cube is boiling the water. My father won a science fair doing this back in the 1930's. -- Roger Long |
Potable Water - The Third Way.
On Fri, 21 Sep 2007 17:35:02 -0500, Brian Whatcott
wrote: The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. Fraid not. It takes the same ammount of heat to boil water as at 212F. Approximately 1175 BTU/lb. You might save a little not heating the water all the wqy to 212. |
Potable Water - The Third Way.
"Brian Whatcott" wrote in message ... You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] Brian Whatcott Altus OK Lame suggestion and unworkable on most boats. Ya gotta think outta the box, man. However, there is another way. I thought it up all by my lonesome. All you need is a reverse osmosis membrane. You put it into a chamber that is vented to atmosphere on the inside and to the ocean on the outside of the membrane. You lower it into the ocean to a depth of only 500 feet and the pressure of the water is enough to push fresh water through the membrane into the chamber. When it gets full you haul it up and empty in into your tanks. Reverse osmosis without any energy used to get it. Ain't Wilbur brilliant? Wilbur Hubbard |
Potable Water - The Third Way.
"N:dlzc D:aol T:com \(dlzc\)" wrote in news:pv_Ii.42363$L_
: What Brian left to the reader's imagination, is that the head space of the tubes is at a near perfect vacuum, flooded only with water vapor. You might recall that a perfect vacuum will lift a column of water about 32 feet, on a high pressure day. Or had you not figured that out? David A. Smith There's a limit to the vacuum boiling. After a certain point, water goes from a solid straight to a gas with no liquid state, just like CO2 does at atmospheric pressure. You can't pull a full vacuum on it and get liquid water. http://invsee.asu.edu/ed/phase/phasefeat.htm (see graph this website, point t.p.) Larry -- Search youtube for "Depleted Uranium" The ultimate dirty bomb...... |
Potable Water - The Third Way.
"Roger Long" wrote in news:46f53eef$0$5006
: My father won a science fair doing this back in the 1930's. -- Roger Long Was his real name Don Herbert and he worked for GE?... Larry -- I don't think I ever missed a Mr Wizard TV show. Of course, if you put the same shows on, today, Mr Wizard would be so far over the heads of the kids with less than Master's Degrees.....they couldn't follow along...(c; |
Potable Water - The Third Way.
Dear Wilbur Hubbard:
"Wilbur Hubbard" wrote in message anews.com... .... Lame suggestion and unworkable on most boats. Ya gotta think outta the box, man. However, there is another way. I thought it up all by my lonesome. All you need is a reverse osmosis membrane. You put it into a chamber that is vented to atmosphere on the inside and to the ocean on the outside of the membrane. You lower it into the ocean to a depth of only 500 feet and the pressure of the water is enough to push fresh water through the membrane into the chamber. When it gets full you haul it up and empty in into your tanks. Reverse osmosis without any energy used to get it. Ain't Wilbur brilliant? You are still displacing that much water... not a small feat. David A. Smith |
Potable Water - The Third Way.
Dear Larry:
"Larry" wrote in message ... "N:dlzc D:aol T:com \(dlzc\)" wrote in news:pv_Ii.42363$L_ : What Brian left to the reader's imagination, is that the head space of the tubes is at a near perfect vacuum, flooded only with water vapor. You might recall that a perfect vacuum will lift a column of water about 32 feet, on a high pressure day. Or had you not figured that out? There's a limit to the vacuum boiling. After a certain point, water goes from a solid straight to a gas with no liquid state, just like CO2 does at atmospheric pressure. It actually goes into this state at very high pressures too. But you are talking "below" the triple point, which is 0.1degC: http://www.sv.vt.edu/classes/MSE2094...es/triple.html .... not much of a problem above this temperature. You can't pull a full vacuum on it and get liquid water. http://invsee.asu.edu/ed/phase/phasefeat.htm (see graph this website, point t.p.) Not a full vacuum, since water vapor does fill it. And if you boil too fast, you lose your two columns of water. And if you don't refresh the contents of the two columns then you start having scaling issues. Not a slam dunk, but not a bad idea either. David A. Smith |
Potable Water - The Third Way.
Larry, I think you are confusing the pressure/pull of a standing/ suspended 40 ft water column and that of a 40 ft air column. Chris of a On Sep 21, 6:21 pm, Larry wrote: Brian Whatcott wrote : You've heard all about distilling water, and you've heard all about reverse osmosis, but you haven't heard about low-cost, low energy stills: they are brand new. Briefly: Take one forty ft vertical tube filled with saline. Take one forty ft vertical tube filled with fresh water. Connect them with a little engineering help - at the top. The boiling point of water at sea level pressure is about 100 deg C The boiling point of water at the top of a sealed 40 ft column of water is near ambient. So, it doesn't take much heat to boil the brackish water, and have it pass to the fresh column where it is slightly cooled to hold the near vacuum conditions at the boiling level. [An engineering effort of a U of Utah group I think] Brian Whatcott Altus OK My deepest apologies to the engineers who may be rolling under their desks, crushing their pocket protectors. It took me a while to stop chortling. I nearly lost my Chinese dinner! Psst...Brian....40'? What about the lake above 40', it's 400' deep and above 40' ASL. It hasn't boiled away in millions of years from all that pressure and lack of pressure. In Tehran, Iran, my apartment was about 7000' ASL. Water DID boil at a lot lower temperature. Making a cake at 7000' altitude is simply amazing! ONE little cake mix makes 4 cakes!.....er, ah, after you clean out the oven from putting ALL the cake mix in the pan, filling the oven! But, alas, even at 7000', the water in my glass didn't boil itself at ambient temperature, even at 110F out on the lawn! Every engineering firm across the planet is going to be a jolly place after hearing about this on Monday...(c; Larry -- Sure glad it doesn't work that way! We'd all be DEAD! |
Potable Water - The Third Way.
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Potable Water - The Third Way.
On Sat, 22 Sep 2007 10:55:52 -0500, Brian Whatcott
wrote stuff and I replied: But what is the cheap source of getting the vacuum? I figured there had to be a vacuum, although it was not said. But how do you get it? Well no, he obviously hadn't figured that out. Nor can anybody figure out what is going to hold a column of water 40 ft high as was stated in the original post. The tubes may be 40 feet but the column of water will be considerably less. How much less will depend on how much energy is heating on the hot side and how much energy is cooling on the cool side. The total amount of energy needed is not going to be any different than any other distilling method. Unless you have the free or cheap sources of cooling and heating at specific temperatures this isn't going to work any better either. -jim Well, at least this respondent Jim, is operating at shall we say the 7th grade level of science/engineering insight. Like so many other products of the domestic school system, he seems to have a severe case of self-esteem syndrome. Still, he may be retrievable, starting with a science demonstration he may have missed. Place a beaker of water in a bell-jar and pump the air out. When 99% of the air has been pumped out, the water in the beaker is boiling vigorously, until, in the usual way, the beaker boils dry. The beaker feels cool to the touch, naturally. To quote him: "unless I have a cheap source of heating this won't work..." For the $64 prize: NOW do you get it? Brian Whatcott Altus OK Human bevaviour: Bestiality with a brain |
Potable Water - The Third Way.
Dear OldNick:
"OldNick" wrote in message ... On Sat, 22 Sep 2007 10:55:52 -0500, Brian Whatcott wrote stuff and I replied: But what is the cheap source of getting the vacuum? I figured there had to be a vacuum, although it was not said. But how do you get it? Fill the tubes, with a small air bubble in between. Lift the tube at the bubble. No small feat if you are looking to make hundreds of gallons per day, but a one-shot expense... David A. Smith |
Potable Water - The Third Way.
On Sat, 22 Sep 2007 20:43:48 -0700, "N:dlzc D:aol T:com \(dlzc\)"
wrote stuff and I replied: Then how do you keep the freshwater tube so cool? It has to be a _lot_ cooler, not so? Is this a continuous or pulsed process? How do you maintain stasis and extract fresh water? If you have a small air bubble, where does the extracted fresh water go? etc Fill the tubes, with a small air bubble in between. Lift the tube at the bubble. No small feat if you are looking to make hundreds of gallons per day, but a one-shot expense... David A. Smith Human bevaviour: Bestiality with a brain |
Potable Water - The Third Way.
Dear Old Nick:
"OldNick" wrote in message ... On Sat, 22 Sep 2007 20:43:48 -0700, "N:dlzc D:aol T:com \(dlzc\)" wrote stuff Fill the tubes, with a small air bubble in between. Lift the tube at the bubble. No small feat if you are looking to make hundreds of gallons per day, but a one-shot expense... and I replied: Then how do you keep the freshwater tube so cool? It has to be a _lot_ cooler, not so? Likely, yes. You could use evaporative cooling (of brine) on that side, and solar heating on the other side. Is this a continuous or pulsed process? I woudl assume it could be either, depending on the sophisticatioin of your control process. How do you maintain stasis and extract fresh water? Ever seen a mercury barometer? The bottom end of the tube ends in a "pan" open to atmosphere. The bottom end of both tubes can simply be sunk... one in the ocean, and one in a wet well for a pump station. If you have a small air bubble, where does the extracted fresh water go? The air bubble expands when the vaccum is created. etc etc. Take your shades off, dude. It is coloring everything you see... It isn't the greatest thing since sliced bread. But it is another process, and a viable one. David A. Smith |
Potable Water - The Third Way.
On Sun, 23 Sep 2007 21:57:56 +0800, OldNick
wrote: .... Then how do you keep the freshwater tube so cool? It has to be a _lot_ cooler, not so? I'm probably going to regret responding, but I will anyway, with a question: What is the difference in temperature between steam and water, both at the boiling temperature of water, whatever it may be? Cooler means lower temperature, right? OK you can now answer your own question. I hope. Brian W |
Potable Water - The Third Way.
Dear Brian Whatcott:
"Brian Whatcott" wrote in message ... On Sun, 23 Sep 2007 21:57:56 +0800, OldNick wrote: ... Then how do you keep the freshwater tube so cool? It has to be a _lot_ cooler, not so? I'm probably going to regret responding, but I will anyway, with a question: What is the difference in temperature between steam and water, both at the boiling temperature of water, whatever it may be? Cooler means lower temperature, right? OK you can now answer your own question. I hope. You don't happen to like bitters, do you? ;) David A. Smith |
Potable Water - The Third Way.
On Sun, 23 Sep 2007 11:29:46 -0700, "N:dlzc D:aol T:com \(dlzc\)"
wrote: Dear Brian Whatcott: You don't happen to like bitters, do you? ;) David A. Smith Angostura I can take or leave: India Pale Ale works for me, but not if I've gone for a Burton. :-) Brian W |
Potable Water - The Third Way.
On Sun, 23 Sep 2007 18:10:09 GMT, Brian Whatcott
wrote stuff and I replied: You are a rude and arrogant prick On Sun, 23 Sep 2007 21:57:56 +0800, OldNick wrote: ... Then how do you keep the freshwater tube so cool? It has to be a _lot_ cooler, not so? I'm probably going to regret responding, but I will anyway, with a question: What is the difference in temperature between steam and water, both at the boiling temperature of water, whatever it may be? Cooler means lower temperature, right? OK you can now answer your own question. I hope. Brian W Human bevaviour: Bestiality with a brain |
Potable Water - The Third Way.
On Mon, 24 Sep 2007 09:38:16 +0800, OldNick
wrote stuff and I replied: and snickering, snide and childish as well You are the sort of cliqueish dolt that spoils useful NGs like this. If you have KF'd me, you simply prove your weak, childish nature. It's shame. You do actually seem to have a lot of knowledge. IT's a pity you have to use it to sneer and brag rather thatn help those "lesser" than you On Sun, 23 Sep 2007 18:10:09 GMT, Brian Whatcott wrote stuff and I replied: You are a rude and arrogant prick On Sun, 23 Sep 2007 21:57:56 +0800, OldNick wrote: ... Then how do you keep the freshwater tube so cool? It has to be a _lot_ cooler, not so? I'm probably going to regret responding, but I will anyway, with a question: What is the difference in temperature between steam and water, both at the boiling temperature of water, whatever it may be? Cooler means lower temperature, right? OK you can now answer your own question. I hope. Brian W Human bevaviour: Bestiality with a brain Human bevaviour: Bestiality with a brain |
Potable Water - The Third Way.
On Sep 22, 11:12 am, "Roger Long" wrote:
There's another neat way you can demonstrate this with minimal equipment. Take a tight fitting jar and get the water boiling vigerously in it with the cap on loose enough to let the steam out. When it is full of dense steam and about 1/3 boiling water, remove instantly from heat and tighten cap. When everything is cooled to room temperature, put an ice cube against the jar and the water will start to boil. The ice condenses the water vapor further, reducing the pressure to the point where the water will boil at room temperature. I've seen it done and it looks like the ice cube is boiling the water. My father won a science fair doing this back in the 1930's. -- Roger Long http://www.metacafe.com/watch/414997/boiling_using_ice/ Joe |
Potable Water - The Third Way.
On Sep 25, 8:54 am, OldNick wrote:
On Mon, 24 Sep 2007 09:38:16 +0800, OldNick wrote stuff and I replied: and snickering, snide and childish as well You are the sort of cliqueish dolt that spoils useful NGs like this. .... "Go away" ... If you have KF'd me, you simply prove your weak, childish nature. .... "Stay and argue with me" ... It's shame. You do actually seem to have a lot of knowledge. IT's a pity you have to use it to sneer and brag rather thatn help those "lesser" than you .... "I will smear **** on you, if you don't argue with me" ... Human bevaviour: Bestiality with a brain Human bevaviour: Bestiality with a brain How is it that you complain about other's behavior, yet you form not one response but *two*, that show exactly the behavior your signature talks about. Is that signature line a complaint, an acknowledgement, or a promise? Be good to know. Because it seems like we have a choice. David A. Smith |
Potable Water - The Third Way.
On Sep 22, 10:39 pm, OldNick wrote:
On Sat, 22 Sep 2007 10:55:52 -0500, Brian Whatcott wrote stuff and I replied: But what is the cheap source of getting the vacuum? I figured there had to be a vacuum, although it was not said. But how do you get it? Gravity. |
Potable Water - The Third Way.
On Thu, 27 Sep 2007 13:54:13 -0000, "jim.isbell"
wrote: On Sep 22, 10:39 pm, OldNick wrote: On Sat, 22 Sep 2007 10:55:52 -0500, Brian Whatcott wrote stuff and I replied: But what is the cheap source of getting the vacuum? I figured there had to be a vacuum, although it was not said. But how do you get it? Gravity. Wishful thinking. Where are you going to get the feedwater containing no noncondensible gasses in solution? In all real distillation plants a continuosly operating vacuum pump is required to maintain vacuum and prevent the condensers from filling with noncondensible gasses. There is no way you are going to eliminate the vacuum pumps with any kind of inverted tube arrangement. For reasonable efficiency real distillation plants are multi-stage, where the latent heat of condensation from one stage is used to boil feedwater in the next stage, with up to 5 stages being used in larger plants (in the days before reverse osmosis made them uneconomical by comparison). Sucessive stages operate at lower pressures, and corresponding lower temperatures. The 1100 or so BTU required to boil one pound of water can thus boil up to 5 pounds of water instead. You still need enough thermal gradient to get the heat to flow through all those heat exchangers. By using low thermal differentials between the hot and cold ends you either reduce capacity to a pittance or require huge and expensive heat exchangers, in either case not competitive. TANSTAAFL. |
Potable Water - The Third Way.
On Thu, 27 Sep 2007 21:25:39 GMT, Glen Walpert
wrote: On Thu, 27 Sep 2007 13:54:13 -0000, "jim.isbell" wrote: On Sep 22, 10:39 pm, OldNick wrote: On Sat, 22 Sep 2007 10:55:52 -0500, Brian Whatcott wrote stuff and I replied: But what is the cheap source of getting the vacuum? I figured there had to be a vacuum, although it was not said. But how do you get it? Gravity. Wishful thinking. Where are you going to get the feedwater containing no noncondensible gasses in solution? In all real distillation plants a continuosly operating vacuum pump is required to maintain vacuum and prevent the condensers from filling with noncondensible gasses. There is no way you are going to eliminate the vacuum pumps with any kind of inverted tube arrangement. For reasonable efficiency real distillation plants are multi-stage, where the latent heat of condensation from one stage is used to boil feedwater in the next stage, with up to 5 stages being used in larger plants (in the days before reverse osmosis made them uneconomical by comparison). Sucessive stages operate at lower pressures, and corresponding lower temperatures. The 1100 or so BTU required to boil one pound of water can thus boil up to 5 pounds of water instead. You still need enough thermal gradient to get the heat to flow through all those heat exchangers. By using low thermal differentials between the hot and cold ends you either reduce capacity to a pittance or require huge and expensive heat exchangers, in either case not competitive. TANSTAAFL. Ah well, another great idea skuppered by dat old devil science :-) Bruce in Bangkok (brucepaigeATgmailDOTcom) |
Potable Water - The Third Way.
Dear Glen Walpert:
"Glen Walpert" wrote in message ... On Thu, 27 Sep 2007 13:54:13 -0000, "jim.isbell" wrote: On Sep 22, 10:39 pm, OldNick wrote: On Sat, 22 Sep 2007 10:55:52 -0500, Brian Whatcott wrote stuff and I replied: But what is the cheap source of getting the vacuum? I figured there had to be a vacuum, although it was not said. But how do you get it? Gravity. Wishful thinking. Where are you going to get the feedwater containing no noncondensible gasses in solution? In all real distillation plants a continuosly operating vacuum pump is required to maintain vacuum and prevent the condensers from filling with noncondensible gasses. There is no way you are going to eliminate the vacuum pumps with any kind of inverted tube arrangement. But they don't have to be large, and they don't even have to run continuously (just frequently). There are also going to be controls... You could even run it without a vacuum pump until it shut itself down, drop and purge the gas bubble, then "forklift" your pipes back up. And do it at less than the melting point of plastic (should that be important). For reasonable efficiency real distillation plants are multi-stage, where the latent heat of condensation from one stage is used to boil feedwater in the next stage, with up to 5 stages being used in larger plants (in the days before reverse osmosis made them uneconomical by comparison). Scaling is real problem too... Sucessive stages operate at lower pressures, and corresponding lower temperatures. The 1100 or so BTU required to boil one pound of water can thus boil up to 5 pounds of water instead. You still need enough thermal gradient to get the heat to flow through all those heat exchangers. By using low thermal differentials between the hot and cold ends you either reduce capacity to a pittance or require huge and expensive heat exchangers, in either case not competitive. TANSTAAFL. .... a characteristic article ... http://www.hcn.org/servlets/hcn.Arti...ticle_id=17136 This was not proposed to be a source of free energy, violate the second law of thermodynamics, or poke fingers in anyone's eyes. I think it was something that someone could do fairly cheaply, to get drinkable water from salt water. In other words "a graduate or undergraduate college project". I just wonder if you get any improvement in what is left in the brine, vs. what also evaporates at the lower temperatures... David A. Smith |
Potable Water - The Third Way.
On Thu, 27 Sep 2007 18:06:47 -0700, "N:dlzc D:aol T:com \(dlzc\)"
wrote: Dear Glen Walpert: "Glen Walpert" wrote in message .. . On Thu, 27 Sep 2007 13:54:13 -0000, "jim.isbell" wrote: On Sep 22, 10:39 pm, OldNick wrote: On Sat, 22 Sep 2007 10:55:52 -0500, Brian Whatcott wrote stuff and I replied: But what is the cheap source of getting the vacuum? I figured there had to be a vacuum, although it was not said. But how do you get it? Gravity. Wishful thinking. Where are you going to get the feedwater containing no noncondensible gasses in solution? In all real distillation plants a continuosly operating vacuum pump is required to maintain vacuum and prevent the condensers from filling with noncondensible gasses. There is no way you are going to eliminate the vacuum pumps with any kind of inverted tube arrangement. But they don't have to be large, and they don't even have to run continuously (just frequently). There are also going to be controls... The vacuum pumps need to be sized to the load, and it is not a foregone conclusion that a larger pump running intermittently would be more efficient than a smaller one running continuosly. Consider also that the vacuum pump cannot pump out just the noncondensible gasses, it must pump out the gas mix in the condenser which will be mostly water vapor - the pumping rate establishes the percentage noncondensible gasses in the condenser, amd the optimum rate needs to be established as part of a distillation plant design. You could even run it without a vacuum pump until it shut itself down, drop and purge the gas bubble, then "forklift" your pipes back up. Does this use less energy per gallon produced? And do it at less than the melting point of plastic (should that be important). For reasonable efficiency real distillation plants are multi-stage, where the latent heat of condensation from one stage is used to boil feedwater in the next stage, with up to 5 stages being used in larger plants (in the days before reverse osmosis made them uneconomical by comparison). Scaling is real problem too... True, but one which can be solved by limiting brine concentration and with chemical treatment and/or periodic cleaning. Sucessive stages operate at lower pressures, and corresponding lower temperatures. The 1100 or so BTU required to boil one pound of water can thus boil up to 5 pounds of water instead. You still need enough thermal gradient to get the heat to flow through all those heat exchangers. By using low thermal differentials between the hot and cold ends you either reduce capacity to a pittance or require huge and expensive heat exchangers, in either case not competitive. TANSTAAFL. ... a characteristic article ... http://www.hcn.org/servlets/hcn.Arti...ticle_id=17136 This was not proposed to be a source of free energy, violate the second law of thermodynamics, or poke fingers in anyone's eyes. As usual with this sort of article there are no meaningful numbers included, perhaps because a complete design analysis has not been done. I think it was something that someone could do fairly cheaply, to get drinkable water from salt water. In other words "a graduate or undergraduate college project". Doing an analysis of this approach would be a good student exercise. Not much point building one without doing the anylysis first - a complete engineering analysis including the selection or design of all heat exchangers, mist eliminators, pumps, piping etc., including both performance and cost calculations. It is always cheaper to optimize a pencil and paper or computer model than hardware, especially for something so well understood as heat transfer and fluid flow. I just wonder if you get any improvement in what is left in the brine, vs. what also evaporates at the lower temperatures... David A. Smith I doubt if that would be much of a factor. What contaminants would be in the feedwater which would evaporate less compared to water as boiling point is reduced by low pressure? The biggest issue with distillate quality is carryover; a fine mist of unevaporated water droplets are inevitably produced by boiling regardless of temperature, and while most of these can be separated out, some always make it through to the condenser. This is a big issue where biological contamination exists in the feedwater, requiring chlorination of the distillate to make it potable. It might be possible to eliminate this factor by eliminating the boiling of bulk liquid, and instead evaporating from a thin film of water flowing over the heat exchanger surfaces, but I doubt if it would be cost effective. Perhaps it would be another good student exercise. |
Potable Water - The Third Way.
Dear Glen Walpert:
On Sep 28, 7:09 am, Glen Walpert wrote: On Thu, 27 Sep 2007 18:06:47 -0700, "N:dlzc D:aol T:com \(dlzc\)" .... Gravity. Wishful thinking. Where are you going to get the feedwater containing no noncondensible gasses in solution? In all real distillation plants a continuosly operating vacuum pump is required to maintain vacuum and prevent the condensers from filling with noncondensible gasses. There is no way you are going to eliminate the vacuum pumps with any kind of inverted tube arrangement. But they don't have to be large, and they don't even have to run continuously (just frequently). There are also going to be controls... The vacuum pumps need to be sized to the load, and it is not a foregone conclusion that a larger pump running intermittently would be more efficient than a smaller one running continuosly. Consider also that the vacuum pump cannot pump out just the noncondensible gasses, it must pump out the gas mix in the condenser which will be mostly water vapor - So you can get some condensate here, but it will likely have "vacuum pump oil" in it... the pumping rate establishes the percentage noncondensible gasses in the condenser, amd the optimum rate needs to be established as part of a distillation plant design. You could even run it without a vacuum pump until it shut itself down, drop and purge the gas bubble, then "forklift" your pipes back up. Does this use less energy per gallon produced? Available on a desert island. Simple block and tackle would do. Since the (de)compression rate is likely low, and the condensation production rate is necessarily low, if you were not using animal power, it could be *more* efficient. But you still have to supply or waste a good deal of heat. .... For reasonable efficiency real distillation plants are multi-stage, where the latent heat of condensation from one stage is used to boil feedwater in the next stage, with up to 5 stages being used in larger plants (in the days before reverse osmosis made them uneconomical by comparison). Scaling is real problem too... True, but one which can be solved by limiting brine concentration and with chemical treatment and/or periodic cleaning. In the case of the marine vacuum distillation unit, they simply have a constant flow of brine. Probably need to have a "tube within a tube" to refresh the fluid near the boiling interface. Sucessive stages operate at lower pressures, and corresponding lower temperatures. The 1100 or so BTU required to boil one pound of water can thus boil up to 5 pounds of water instead. You still need enough thermal gradient to get the heat to flow through all those heat exchangers. By using low thermal differentials between the hot and cold ends you either reduce capacity to a pittance or require huge and expensive heat exchangers, in either case not competitive. TANSTAAFL. ... a characteristic article ... http://www.hcn.org/servlets/hcn.Arti...ticle_id=17136 This was not proposed to be a source of free energy, violate the second law of thermodynamics, or poke fingers in anyone's eyes. As usual with this sort of article there are no meaningful numbers included, perhaps because a complete design analysis has not been done. More than likely omitted because: - the reporter's eyes were glazing over, or - they are working on a patent (since you can probably even patent cheese now). I think it was something that someone could do fairly cheaply, to get drinkable water from salt water. In other words "a graduate or undergraduate college project". Doing an analysis of this approach would be a good student exercise. Not much point building one without doing the anylysis first - a complete engineering analysis including the selection or design of all heat exchangers, mist eliminators, pumps, piping etc., including both performance and cost calculations. It is always cheaper to optimize a pencil and paper or computer model than hardware, especially for something so well understood as heat transfer and fluid flow. I just wonder if you get any improvement in what is left in the brine, vs. what also evaporates at the lower temperatures... I doubt if that would be much of a factor. What contaminants would be in the feedwater which would evaporate less compared to water as boiling point is reduced by low pressure? Water does get involved in some azeotropes (some alcohols), so depression of boiling point would not help there. And thermodynamically, if one of the things you were trying to remove became a solid at high vacuum (NaOH maybe?) it might help. The biggest issue with distillate quality is carryover; a fine mist of unevaporated water droplets are inevitably produced by boiling regardless of temperature, and while most of these can be separated out, some always make it through to the condenser. This is a big issue where biological contamination exists in the feedwater, Such as natural brines... requiring chlorination of the distillate to make it potable. It might be possible to eliminate this factor by eliminating the boiling of bulk liquid, and instead evaporating from a thin film of water flowing over the heat exchanger surfaces, but I doubt if it would be cost effective. Perhaps it would be another good student exercise. I wonder if the increased viscosity of droplets at lower temperature would assist in more efficient removal? Thanks for the discussion... David A. Smith |
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