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Fw: [biofuel] How to build a still, Chapter Two

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    Message 1 of 1 , Apr 5, 2000
      Steve Spence
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      ----- Original Message -----
      From: <robertwarren@...>
      To: <biofuel@egroups.com>
      Sent: Wednesday, April 05, 2000 9:57 PM
      Subject: [biofuel] How to build a still, Chapter Two

      Building the Charles 803 Still
      Chapter 2, Principals of Operation of an Alcohol Still

      In order to ensure that you are consistently able to make high
      quality, high proof alcohol fuel (ethanol), at a pre-determined range
      of 160 to 180 proof, it is important to understand the functions of
      the various sections of the still before you get started.
      Furthermore, we must realize that in order to make our own
      alcohol fuel to replace or displace the use of gasoline (petrol), we
      must produce uniformly high quality fuel, so we need to understand
      this process. Running a still is actually a fun thing to do, as it
      gives you an incredible sense of self-reliance. The first time you
      pour some home-brew in your car or truck, and realize how much power
      you have (the same horsepower as before), it is really a great
      feeling! Also, you can make this fuel for $0.85/gallon or less!
      Dimensions on the blueprints are provided for a reason, even
      if it may not seem exactly clear as you proceed with this project. A
      1/4" tolerance of error may be allowed on vertical dimensions. But,
      when you are drilling holes through the 3 "copper pipe, the hole size
      must be precise! The places where a pipe extends through the curved
      wall of the 3"pipe must be pretty much a press-fit if you expect to
      get the solder to take and form a good joint. The still actually
      has no moving parts, other than the cooling coils, which do expand
      contract a little with temperature change.
      I apologize in advance for my readers in other parts of the
      world for not using metric measurements, but even though I am
      completely familiar with metric conversions, I am not familiar with
      standardized plumbing and pipe sizes in the world of metrics. So,
      except that I have provided you with temperatures in degrees Celsius,
      all measurements are US standards.
      A still, or distillation column, is nothing more than a
      temperature-controlled chamber where alcohol vapors and water vapors
      may separate, each according to its inherent boiling
      point/condensation point. For example, at sea level, water boils at
      212°F (100°C). Steam, on the other hand, condenses into water
      also at
      100° C. Heat is easily lost if it has somewhere cooler to go.
      the still is made out of copper pipe, which is a good conductor of
      heat, some of the heat is lost through radiation out into the
      atmosphere. It is important to remember this, as this will be a
      on very cold or windy days, and you will find that you have to adjust
      your temperature control valve a little differently than the setting
      for summertime operation. The other place the heat escapes, by
      is into the cooling water flowing through the 1/4 "copper tubing
      coiled up on the inside of the still. Since this will normally be
      either pressurized city water or well water (because you need to hook
      up your garden hose to the hose fitting on the temperature control
      valve), it is clean hot water. When we traveled with our still and
      demonstrated it at county fairs, we would use this hot water to make
      instant coffee or tea. If you are going to be running several batches
      of mash, you may want to use this heated water to warm up whatever
      feedstock you are going to use and facilitate your mixing process
      prior to adding enzymes or yeast. This is really a very small amount
      of hot water, but for efficiency's sake, we do like to recover and
      whatever heat energy we can. The subject of enzymes and yeast is
      thoroughly covered in the Alcohol Fuel Manual, which you may download
      from the Journey to Forever Web site.
      Pure alcohol boils at 174° F (78.9° C). Conversely, alcohol
      condense into a liquid at 174°F (78.9° C). To be perfectly
      accurate in
      the real world of observation, it has to be a little beyond the point
      of condensation. In the actual operation of this still, you want to
      keep the temperature just above this point, because control point is
      measured below the condenser and at the very top of the reflux
      where you want the alcohol steam to be hot enough to continue to
      into the condenser. Therefore, the control valve should be set to
      at 176° F (80° C), at sea level. If you are living in the
      you will have to adjust the temperatures to allow for the fact that
      water boils at a lower temperature at high altitude. In Denver, Co ,
      the mile high city (5,280 ft elevation), water boils at only 190°F
      (87.8° C) degrees. This means that the control setting for the
      is also much lower, around 154°F or 155°F (68° C).
      The still is divided up into three main sections. The bottom
      section is labeled the bubbler, (it can also be called a doubler,
      because this little section is where the steam first enters the
      and immediately doubles in concentration of alcohol vapors). The
      threaded female adapter near the bottom is where a high temperature
      type hose shall be attached. This hose is what conveys the hot steam
      from the top of the cooker to the still. As the hot steam enters the
      still, it is immediately directed downwards by the 90 degree fitting.
      This bottom section is filled with cold water just before the
      distillation process is started. A little more than a quart of water
      is added through the 45° fitting just exactly opposite where the
      temperature hose attaches. If you have followed the dimensions
      properly during construction, at the point which too much water is
      added, it will then leak out the tee fitting just below the
      45°fitting. This is the proper water level.
      This small amount of water initially acts as a vapor trap, which
      effectively keeps the alcohol vapor from being lost prematurely
      the water temperature is high enough. When you first start the cooker
      to boiling, the alcohol starts boiling before the water does,
      theoretically. In actual practice, the alcohol is thoroughly
      in the water, so what actually happens is that the mash solution in
      the cooker boils at a slightly lower temperature due to the 5 to 10%
      amount of alcohol in solution. As the beer solution in the cooker
      first starts to boil, the alcohol starts to come out of solution.
      However, we do not want this vapor to escape just yet, before we
      establish an equilibrium temperature within the entire still, hence
      the water trap. This, then, is the first function of the doubler.
      The second function of the bubbler is to strip water content out of
      the steam. When the beer in the cooker does reach a full rolling
      the pressure starts to rise and the steam has to go somewhere. We
      direct it downwards into the water trap, because the liquid water
      cool the steam. This steam is immediately cooled down as much as 10
      degrees (it really won't have time to be cooled down more than that)
      and this will effectively remove half of the water content of the
      steam. Now, when steam hits a liquid it is going to be under
      and it wants to displace that liquid and drive it upwards. So, we try
      to baffle the flow of the steam so that a little bit has a chance to
      escape out the sides, and go up, since this is where it wants to go
      (heat rises). This is the purpose of the little holes you will drill
      in the bottom side of the 3/4"ninety degree elbow and also in the
      3/4"x 1/2"reducer below it. Some of the steam is then allowed to
      escape upwards instead of having to go the extra inch or two
      downwards. You will also need to drill a single 3/16" hole at the top
      corner of the 3/4"ninety degree elbow (I will remind you about this
      later on) as this allows a small bit of steam to go immediately
      upwards and thus hasten the upwards movement and start warming the
      upper sections.
      Now, just below that ¾"ninety° elbow, is the baffle plate which
      to deflect the steam back upwards, so that we do not lose it out the
      blow-off. The baffle plate is actually a stainless steel shower drain
      cover plate, which you will find in the plumbing section of your
      hardware store. You need to buy two of them: one 3", which exactly
      fits into the coupling which joins the top of the bubbler section
      the bottom of the reflux column. The other should be 2 ½"diameter.
      you have trouble finding this smaller size, and you may, you may buy
      two of the 3"and cut it down to a smaller diameter with a pair of tin
      snips or metal shears. The other possibility for making this
      plate is to use a piece of copper plate which can be cut to size and
      drilled with a whole lot of holes. This baffle plate is supported by
      short piece of ¾"or 1"copper pipe ( this size doesn't matter),
      is surrounded by three or four copper or brass Brillo pads ( or brass
      or copper lathe shavings). The Brillo pads should be readily
      available at a grocery store, but do not buy or try to use the kind
      scouring pads which are nothing but steel wool, as the steel will
      corrode and dissolve into a pile of rust rather quickly. I will
      discuss the drain port and the condensed water run-off (the ½ "
      and tee fittings on the right side of the bubbler section) later on
      when we discuss the actual operation of the still.

      So, assuming we are working at sea level, the middle section needs to
      stay hotter than 174°F, so that the steam is still steam and
      to rise into the very top-most section of the still. Notice that the
      alcohol drain fitting, which consists of a 1/2"pipe coming out of the
      lowest point of the top section of the still (it is labeled "fuel
      outlet" in Figure 1) is the only place the still is completely open
      atmosphere. Therefore, this opening is the path of least resistance
      for the steam and thus the steam wants to rise and exit out this
      However, the key to obtaining very high proof alcohol is to keep the
      temperature of entrance to this top section just above 174° F, so
      the alcohol is still steam and will rise into the top section.
      Therefore, you want the temperature of this area just below the
      transition between the mid section and the top section to be exactly
      176°F (80° C), as measured both by the temperature gauge which
      you can
      see, as well as the temperature probe for the automatic control
      At this temperature, 176° F, the alcohol is still a vapor, but the
      water is a liquid, so it falls back down to the bottom of the still.
      You will be removing so much water from your barrel of boiling beer
      that the extra amount of water has to drain off somewhere, so this is
      why you have a "condensed water runoff" which is so labeled in Figure
      1, near the bottom.

      During the distillation process, the whole point is the
      establish a dynamic equilibrium in the temperature probe area of the
      still. You have an automatic control valve which responds instantly
      temperature change, so this is what cools the 212°F steam down to
      precisely 176 F. Then the steam is almost pure alcohol vapor steam,
      and rises into the top section where the coldest water from the
      hose enters first. The very top chamber, the condenser, is somewhat
      thermally isolated from the rest of the still, as it has to remain
      several degrees cooler than the reflux section below.

      The top section of the still is pretty easy to understand. It is
      capped at the top with a soldered fitting, and it only has one
      to the outside: the fuel outlet, which consists of a 1/2"copper pipe
      which is angled down at a 45° angle. You will attach a 5/8"
      clear vinyl plastic hose to this short piece of pipe, and run this
      down to the 5 gallon glass bottle, or whatever container you will use
      to catch your high proof alcohol. We don't like to catch or store
      alcohol in steel fuel cans, as it is a bit corrosive (but not as
      corrosive as methanol), and will rust out the cans. Glass 5-gallon
      water bottles work pretty well, but you might crack one if you change
      the temperature too abruptly. The condensed hot alcohol enters
      when you are cooking off 50 gallon batches of beer, and so the glass
      warms up gradually and isn't a problem.
      The condenser section cooling coil first receives the cold water from
      the garden hose via the automatic temperature control valve, and
      initially enters the top of the top condenser section of the still.
      is a short section of coil, since the condenser section is also
      short. Then the cooling water exits this section and re-enters the
      reflux section just below the temperature probe. The fuel outlet has
      to be at the lowest point of the condenser section, so that you don't
      have trapped alcohol left inside the still when you are finished.
      There is one other detail to this condenser section: while you want
      the opening between the reflux section and the condenser section to
      as wide open as possible, there has to be a physical barrier to the
      packing materials. This is so that if you lay the still down
      horizontally for transporting it, the packing materials are not
      allowed to migrate into the upper condenser section. You will notice
      this in a written note near the top of Detail#1 in the drawing.
      There is one other aspect of the action that takes place in the
      condenser: when steam condenses from a gas into a liquid: the volume
      is decreased by a factor of 1800 times. This means that once alcohol
      starts condensing (you will see the clear liquid through the clear
      vinyl tubing attached to the fuel outlet) it is creating a partial
      vacuum, except for the fact that it is open to atmosphere. However,
      when the alcohol flows out the fuel outlet, this momentarily blocks
      air coming in, and the momentary vacuum helps to pull the steam below
      into the condenser section. This is a desirable effect, if the vapor
      just below the condenser is pretty much pure alcohol, as it helps the
      still to work more efficiently.
      It is possible that this steam in the temperature control zone is too
      high in water content because the bottom section of the still is not
      sufficiently cooled. The only way that you would know that this is
      happening is by seeing that the proof is not as high as you were
      trying to achieve (just remember that when you are measuring hot
      alcohol, you have to consult a temperature conversion table to allow
      for the temperature effects on the hydrometer). The only reasons
      possible for this condition are (1) the temperature valve is not set
      to the right temperature, or (2) the boiler is putting out much too
      much heat for the volume of steam to be cooled by this still.
      Typically, all you have to do is to pay a little more attention to
      operation of the automatic control valve, by making tiny adjustments
      and then watching the temperature gauge at the same instance that the
      valve is opening to release cooling water into the still. The second
      possibility may happen because you are boiling the mash much too
      If you are using a gas flame, you can turn down the flame. If you are
      burning wood, your adjustments may be limited to closing the smoke
      pipe damper, or pulling out the firebox drawer (if you follow my
      recommendation at making a safe and effective wood burning setup). If
      you have access to scrap wood (old pallets, shipping cartons,
      construction waste, etc) this is free fuel, further reducing the cost
      of the finished product.
      So far, we have discussed the top and bottom section of the still,
      have not discussed the middle section, called the reflux section. The
      term reflux refers, in the distillation literature, to the phenomenon
      of the up and down action of the steam vapors, where the steam which
      is being driven upwards is competing with condensed water falling
      downwards. The work reflux means, " to flow back or return,
      to heat so that the vapors condense and return to be heated again."
      (Merriam-Webster's Collegiate Dictionary). The reflux section has
      largest portion of the coiling coils, as this is where the greatest
      temperature change must occur, in this chamber. The lower two-thirds
      of this chamber is also filled with an inert packing materiel. This
      packing material does two things, actually. The first purpose is to
      provide a surface area on which the steam may condense. Secondly, but
      related to this first one, is that the packing material provides a
      cooler surface (initially) which will cool the steam. After the still
      has been in operation for twenty or thirty minutes, the steam has
      likely heated up the packing material quite a bit, so this function
      becomes less important. However, we are still interested in providing
      a maximum amount of surface area on which the water molecules may
      and condense. At the same time, the packing material must not be so
      compacted that it blocks the movement of steam.
      Because the cooker has an external heat source, additional heat
      energy is constantly being fed into the still in the form of live
      steam, and it comes in at the bottom of the still. Cooling water is
      circulating through the inside of the still, and thus, the small
      portion of the steam which contacts with the water cooling coil will
      immediately condense. This water starts falling down towards the
      bottom of the still, but, because of the packing material, it doesn't
      fall freely: it merely drips from one piece of packing material onto
      the piece below it. Now, this water which is dripping downwards cools
      the steam water rising upwards, but the steam is at the same time
      transferring its heat to this condensed water, giving up some of its
      energy. The whole idea here is to create some turbulence and
      interaction between liquid condensed water and the water content of
      the steam. Every time steam heats water, it gives up energy. And yet,
      we don't want it to give up so much energy that we are condensing the
      alcohol vapor prior to reaching the upper chamber. Thus, if some of
      the alcohol vapor has been condensed, and is falling downwards, it
      gets caught on the surface of the packing materials and re-heated so
      that the alcohol turns back into steam and rises to the top of the
      reflux chamber. This last statement is the primary reason for the
      purpose of the reflux chamber.
      We have a huge range of temperature between the condensing points of
      water and alcohol. 212° F minus 174° F is a 38°F (20°C)
      range. Now, the length of the reflux chamber is a critical factor, as
      we likely have a temperature quite close to 212°F at the very
      of the still where the live steam is rolling in, while near the top
      the reflux column, we are trying to closely control this temperature
      within one-half a degree of our desired 176° F. Before the advent
      automatic control valves, this was not an easy objective to achieve.
      On the other hand, most of the alcohol which was home distilled was
      a much lower proof, for drinking purposes. You will be surprised at
      the clarity and purity of the high proof alcohol which this still
      produces. However, 180 proof grain alcohol is too potent to drink (it
      will dehydrate body tissues at an alarming rate, especially in the
      throat and esophagus region). It is also possible that small amounts
      of methanol (wood alcohol) and fusel oils are present, although
      normally when the still is functioning properly, these are removed in
      the bottoms water in the bubbler section.
      Now, there are a couple of minor but key points to the functioning of
      this still to which attention must be paid. You will likely notice
      that the bottoms water does smell a lot like the original beer mash
      solution, and if you measure it with your alcohol hydrometer when
      are done, you will see that you do have a little bit of alcohol in
      bottoms water. You need to save this and add this to your next batch.
      However, if you are saving this water by attaching a clear plastic
      hose to the 1/2"pipe fitting (labeled "condensed water run-off" on
      Figure #1 on the drawing) you must make sure that this hose does not
      go uphill, before it goes down into the bucket or catchment
      This is very important, as for example, if this hose runs up over the
      side of a tall bucket before it drains into the bucket, you have just
      effectively altered the water level inside the bubbler section. We
      want this level to stay consistent with the height of the condensed
      water runoff port, otherwise we may be cooling the steam too fast,
      with too much contact time with the bottoms water. You may find that
      the still is a little easier to operate if you elevate it about eight
      or ten inches above ground level, for example, by sitting it on top
      a couple of concrete blocks. Then you have enough room to use a large
      bucket for the condensed water run-off. You may also need to have an
      extra bucket in case this first one fills up, because it may contain
      perhaps 5% alcohol, and you want to save this to add it to your next
      How much alcohol can you expect to make with this still? It
      all depends on how much feedstock you have available to ferment to
      make alcohol. If you start with 100 gallons of very high sugar
      fruit, such as culled peaches grapes, you may have such a high sugar
      content that you can get 12 or even 14% alcohol content. Above 14%
      alcohol is pretty difficult to obtain as the alcohol content gets so
      high that the yeast starts to die off in the presence of their own
      waste product (alcohol is the pee of the yeast organism, remember?).
      But, for illustrative purposes, lets us say that you have 10% alcohol
      shown on the hydrometer that you have floated in your mash solution.
      If you have 100 gallons of this, the 10% is 10 gallons of high proof
      fuel, approximately. The actual formula, it you are trying to make
      proof (90 % ethanol) in this case would be (100 gal x .10 ) / .9=
      gallons of 180 proof.
      If you are trying to make 160 proof (80 % alcohol, which makes an
      excellent, very economical fuel (more about that later on) and you
      were using culled pears as a feedstock (they are lower in sugar,
      likely yielding around 7.5% alcohol in the Balling hydrometer) then
      your expected yield would be (100 gal x .075)/.8 = 9.4 gallons of 160
      The first few times you run this still, it is recommended that
      you run small batches of 50 gallons of mash at a time, until you get
      little better understanding of the various procedures and tasks ahead
      of you. It may seem at first that it is a lot of work to get only
      or ten gallons of fuel, barely enough for an entire week of in-town
      driving. However, this still is a serious, very high quality tool,
      capable of turning out 7.5 gallons per hour over a twelve hour
      For example, if you had a 1,000 gallon tank of mashed and fermented
      culled pears, in a 12 hour run you would get 93.75 gallons of 160
      proof fuel. The formula, this time, would be 1,000 gal x .075) / .8
      =93.75 gal.
      With proper attention to engine conversion techniques, you can expect
      to achieve exactly the same or possibly better gas mileage with 160
      proof ethanol as you do with gasoline. If some of your fuel and
      feedstock inputs are free, then you only need to count your labor for
      obtaining supplies and running the still. 94 gallons of gasoline
      costs $1.54 per gallon for regular (as of Mar. 27, 2000). So 94
      gallons at $1.54 = $144.76 US.. During the 12 hours of running the
      still, if you automate much of the process, then perhaps you will
      have 3 hours of actual work on and around the still, but it may well
      take you 9 or 10 hours on another day to gather and prepare the
      materials, and to clean up afterwards. So, If you obtain $144.00
      of essentially free fuel, and it takes you 14 hours to do this, then
      you are making $10.00 / hour. This may or may not be worth your time.
      You may choose to pay an employee $7.00/hour to do this work and make
      a profit of $3.00/hour off his time and your capital investment.
      The assumptions in the previous paragraph assume that feedstock is
      free; but, in the real world, everything, even throwing something
      away, has its price. I shall not go into details here, but we are in
      the process of posting other economic and agricultural studies to
      web site which demonstrates that even on a moderately small scale,
      fuel alcohol may be made (including the cost of buying agricultural
      commodity feedstock, but also selling the distillation byproducts)
      $0.85/gallon US.
      One other major point about the economics of this particular still.
      Perhaps you find that you do have large agricultural resources
      available for feedstock. So, you do some number crunching, and you
      find that in order to economically make the amount of fuel you want
      and make the profit margin you need, that you need to make 75
      gallons/hour. No problem! Just build ten of these stills and run them
      in parallel! Better still, make the "Big Brother" version of this
      still and run five of them in parallel for an output of 100 gallons
      high proof , high octane (106 octane) fuel per hour. A modular
      approach will also save you operational coasts as you can adjust flow
      rates and heating requirements according to the timing of when
      feedstocks become available.
      In later chapters I shall describe methods of handling batches of
      various types of feedstock, as well as how to change this still from
      batch process still into a continuos process still. The economic
      challenge of any tool or piece of machinery is to fully utilize its
      inherent capabilities, and the more hours it runs, the more fuel and
      money it makes for you! In addition to the standard industrial
      business model, we should also explore the farm co-op model, or even
      food co-op model, as the need for fuel is a common community need,
      since vital and recyclable resources are spread throughout a
      community. A community co-op run alcohol fuel still makes perfect
      sense as a way that we as a society can free ourselves from the
      shackles of a polluting and militarized petroleum economy.
      Next: Building the still
      Please note: Drawings, and Chapter 3, on assembling and building the
      still shall not be available in the Bio-fuels newsletter, but may be
      ordered from the author, Robert Warren. Other sections on how to run
      the still shall be published in this newsletter.


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