[biofuel] Re biofuel computer

[DAVID REID]

B.P. of ethanol is 78.4 C  (173.1 F). Controls are not too hard to design. It just depends on how sophisticated you want to get. you > >could regulate the flow of water manually and keep it at a slow pace and > let > >the computer do the rest.   I use a solenoid valve to turn the water off and on and a manually adjusted needle valve to control the flow. Please note temperature at takeoff point is different to temperature in boiler Can vary depending on still. This is a point where there is a bit of disagreement over location of sensors. Some people argue that because you want to control the temperature in the boiler which is what controls most of the other temperatures in the column etc that this is where you need the sensor and work from that point. To a degree they are right. I and most people who know what they are doing adopt a slightly different attitude knowing that the most critical temperature point in any still is at the takeoff or condensation point. I therefore mount the critical sensor there working backwards using insulation and other aspects of the design process to minimise the differences between temperature at this point and the boiler. The ideal situation is where you have 2 or 3 sensors each monitoring different points but then the controls and the monitoring situation become a lot more involved. contd below: >Use a 24volt sprinkler system valve, they are ON/OFF and controlled by a > 24V > >signal. A processor could monitor the temp in the top of the column and at > >>178 it would open the valve and let cold water into the cooling coil. you > >could regulate the flow of water manually and keep it at a slow pace and > let > >the computer do the rest. > >The only thing I need to know is where would the temp sensor go? how far up > >the column?   As I said at the takeoff or condenstion point.    would the temp sensor actually touch the cooling coils or would > >it be better to just measure the air temp?   No the temp sensor must not touch the cooling coils. You need to measure the vapour temp at this point. Please note that water vaporised expands to something like 1500  times the volume. Location and depth of sensor is critical. So many of the people designing stills dont have the first clue and there is so much false information out there. Before going further and designing a controller that might work go out and research the subject properly and read a few decent books. Most of the people designing stills are too lazy or too arrogant to do even that. If you can see how someone else achieved a certain goal you can admire it or fault their thinking. Quite often you can even improve upon ther original concept. Firstly you need to separate the chaff from the wheat. That way you may design a controller that works. PIC controls certainly have their place and proper intergration of these in the stills of the future will be commonplace and is one of the better solutions available. All the best with your efforts. B.r.,  David eGroups Sponsor Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html To unsubscribe, send an email to: [EMAIL PROTECTED]