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Sean French
Sean French's picture
Gasifier Instrumentation

Hello All
I have some new toys to show you. These are custom made thermocouples that I have been using on my woodburners. Type K max temp 2100F made from Inconel with compression coupling for air tight seal. I use two of these on my F-150 now and I am getting ready to install a third one. In the pics. there are two 17" probes two 10" and one 3" I also have access to a full line of digital display readers to go with the probes. I personally am very good at breaking all things and I haven't broken one of these probes yet (believe me I tried) good solid unit. Regards Sean

Chris Saenz
Chris Saenz's picture
Wow! Very cool. This could

Wow! Very cool. This could add some much needed remote instrumentation. What's the cost on these and where do we get them?

Sean French
Sean French's picture
Hi Chris,

Hi Chris,
I have a local company here that makes them. They are top quality at a reasonable price all the probes in the pics. are type K and go for $94.77 a piece doesn't matter how long you need the price is about the same. I can get you anything you can dream up. One day I plan to send a probe straight down the hopper to the grate and measure the temps this will not be cheap but I will be wealthy in knowledge. Since these are not sitting on a shelf and made to order please allow up to 2 months to be complete. Good things always take awhile. These probes have been a huge help in understanding gasification and have saved me a lot of heartache. Regards Sean

Henry Austin
Henry Austin's picture
Sean,

Sean,

Any chance you have a PDF Spec sheet for those? They look like they would integrate well with my PLC control system, I would like to see any info you have on them!

Sean French
Sean French's picture
Hi Henry,

Hi Henry,
Very cool a PLC would be great!! Unfortunately
I do not have a spec sheet on them at this time :( I will call the company and get one from them to post here.
Is there anything specific you would like to know ? I can make sure it's on the sheet. Regards Sean

Strike That

I just talked to them they don't have spec sheets because all there work is custom made.
What kind or brand of plc are you running? I can tell you these probes are type K with a millivolt A/C Signal
And your PLC Seimens, Allen Bradley ect. should have a card that adapts to read these probes.
I hope this helps let me know Regards Sean

Henry Austin
Henry Austin's picture
Sean,

Sean,

GE Fanuc PLC's, I dislike Siemens anything (overpriced and unreliable) and Allen Bradly rapes you on hardware and then twice more for the programming software - GE PLC's are available on eBay all day long and I have Proficy already.

I am not yet sure If I will be using thermocouple input cards or analog input cards. If I find sensors/transducers with a 0-10V output or straight up variable resistance I will use the analog cards, else I'll have to source a thermocouple input card.

I like the analog because I have a couple of 16 channel analog cards which will accept 0-10VDC or 4-20ma current. I am also looking for some vacuum transducers (saw some somewhere, cannot remember where) and an airflow sensor (thinking about using older modified automotive analog MAF sensors).

I want to know the temp, vacuum, and airflow at all of the various stages of the unit, so that the PLC can alert me when there are "abnormal" conditions present in the system.

I'm also liking water level sensors (still thinking on a tar level sensor - little more difficult) and some automated drain valves for Michigan's cold winters (trying to prevent freezing and of course, kneeling or lying down in slop).

I definitely have a lot of work to do!

Sean French
Sean French's picture
Hi Henry,

Hi Henry,
You certainly have your work cut out for you !!!! It will be awesome to bring all of these sensors into one main computer and have it report back to you the conditions of a gasification system. This is one of the side projects I have been working on I will help in any way I can. This t-probe company makes a lot of gizmos I just used the millivolt because I all ready had the controllers to go with them. I was thinking about using automotive map sensors for vacuum. And your idea on using a MAF to monitor airflow is great I see no reason that would not work. Keep at it Regards Sean

Steve Unruh
Steve Unruh's picture
Hey HenryA.

Hey HenryA.
Thanks for the experienced heads up on the PLC brand world.
Auto MAF's be fine for the primary air flow.
Produced wood gas flow however . . . . anytime it is intruded, diverted or cooled at all it want's to drop out slightly acid condensate and CO to CO2 revert dropping out a carbon soot particle. Whether you go with hotwire, sonic (Karmen Vortex) or VAF (flapper door) these contaminants are going to corrode and weight/coat deposit and throw off your calibrations.

Any body close you could work with a running woodgas system to see all of this?

Regards
Steve Unruh

Henry Austin
Henry Austin's picture
Steve,

Steve,

This is good information!

Terry Grzyb is the only woodgas driver I know of that is "close", I think he's over west (ish) of Detroit, but otherwise nobody I know of nearby. I "Hope" to have my truck together by end of summer (if the remaining build videos go online in time). I have the truck (Chevy 2500 with a 7.4L 454) & plasma cutter (Lotos LTP5000D) purchased and am still researching welders (I believe I am going with the Millermatic 180) then it's full on construction until I'm done (I have the summer off). I intend to duplicate Wayne's system and after some operating experience slowly integrate advanced monitoring and automation (learn to walk, then attempt to jog).

It is possible, that if I am accurately metering incoming cold air (Flow, temp & density), + I know the internal temp of the unit, + the vacuum being pulled by the engine I can compute the amount of gas being produced, otherwise I may not be able to monitor produced gas flow. Might need a special sensor for these (or a REALLY cheap & readily available 'er replaceable) unit with a housing that allows for easily maintenance or replacement. Monitoring produced gas flow may well be more headache than it is worth but I plan to attempt it at least even if it is abandoned later on as fruitless (love a challenge).

I will have to research the industrial world for corrosion resistant or self-cleaning (wouldn't that be great) air/gas flow sensors. So far I have found a vacuum transducer that should work (ordered one today for bench testing). Sean is on to something with those thermocouples if we can interface them with the PLC (which I need to research further). And I have yet to research water level sensors for the condensate tanks.

Sean French
Sean French's picture
Hi Henry,

Hi Henry,
On the water level sensors how about a simple float switch ??
These are used on boat bilge pumps all kinds of nasty things are in a boats bilge.
If that switch can live in that environment a woodgas condensate tank should be no problem.
This switch will give you a normally open/ normally closed reading.

If you are thinking about a level indicator how about a gas tank sending unit
you would clearly see 1/4 1/2 3/4 to full. wouldn't that be sweet.
Just some thoughts Regards Sean

Henry Austin
Henry Austin's picture
I like the gas tank sending

I like the gas tank sending unit... They are basically a float driven potentiometer.

A few concerns though; Unlike gasoline the wood gas water will likely be corrosive, not sure how long it would last. Of more concern, most (that I have seen - GM's) are completely uninsulated as gasoline is not a conductor of electricity. The condensate mixture may have some electrical conductivity (affecting the reading). Any chance you could test some next time you drain your system? If it's not conductive we have a winner.

Also considering RV tank sensors,... the blackwater level sender should be able to withstand just about anything short of pure acid I would think? I even considered using an RV blackwater tank but they are all plastic nowadays, and I don't know that it would hold up well... might even melt if the gas was warm enough but the sender could be useful in our condensate tanks.

Sean French
Sean French's picture
Hi Henry,

Hi Henry,
Yes your on the right path. We had some weird things happen to our first wood truck but it was an all around
junker so we already tested the condensate it is mildly acid with no conductivity. I would recommend finding
a sending that is insulated or protected from corrosion. The rv sending unit in black water might be the way to go
magnetic hall sensor comes to mind. I toyed around with the plastic condensate idea for awhile haven't done it yet. Would have to be high temp A.B.S. plastic I don't think a rv tank would be beefy enough by itself. I don't see it melting unless something is wrong with the system but vacuum combined with mild heat could = crushed tank.
Regards Sean

Thomas McDaniel
hi

hi
allelectronics has sealed float switches i used 3 of them on a fuel tank at the lab 1 lite= refuel 2 lites half full 3 lites full mine also fed the pc that did the actual fueling
Tom

Henry Austin
Henry Austin's picture
Guys,

Guys,

I think I'm liking this for liquid level measurement;

http://www.nationalmagnetic.com/continuouslevel.html

These could be used to drive analog gauges (old school) an can be wired to provide an analog input to a PLC or other micro controller. I may request a quote (they don't provide prices, that's usually a bad sign) but if need be this is a fairly simple DIY build (compared to the actual gasifier!). Build it with stainless tubing and it should stand up to corrosion just fine.

Sean French
Sean French's picture
Hi Henry,

Hi Henry,
That's exactly what I had in mind when I said magnetic pickup sensor Awesome find

Sean French
Sean French's picture
A little help if possible we

A little help if possible we have a good thread going on instruments. I am going to ask if anyone here has access to a gas analyzer for measuring a wide variety of gases? Hmmm flamable and non flamable Regards Sean

Steve Unruh
Steve Unruh's picture
Hi SeahF

Hi SeahF
There is much used automotive equipment out there for cheap and even sometimes free haul-a-way.
Be care.
Old, Old two gas only able to measure CO and HC's
Old three and four gas pick up CO2 and O2.
Newest five gas stuff picks up NOx's - nitrous oxides.
Old, old equipment was always expensive to keep running and use.
90's manufactured 3 and 4 gas stuff not to bad if still manufacture supported.
ALL take special to buy "Calibration Gas" composed of precisely mixed CO, CO2 and HC (usually methane or a propane) to be able to verify your machine to measure and quote live gas composition with any accuracy.
ALL WILL CLOG UP WITH ANY TARS.

Then there is the combustion Furnace world grade stuff.
Lab grade stuff.

Regards
Steve Unruh

Henry Austin
Henry Austin's picture
I have the vacuum transducer

I have the vacuum transducer now, (Transducers Direct #TDH31BGV01503D004) as well as (2) WIKA vacuum gauges and (2) temp gauges. I plan to construct a simple manifold with the WIKA gauge and the transducer on it very shortly and verify the readings are properly scaled and usable using a vacuum pump for my bench test. I will let all know how it works. If this works well, I'll probably play with either buying or building the float switch we talked about above, and then the thermocouples and flow meters. Not sure why I started with the vacuum transducers but that's where I started.

Interestingly, the Music City Metal temp gauges are oval in shape. From the videos it looks like Wayne has round gauges, did I get the wrong gauges or did I just not notice the oval shape while looking at the photos and videos?

Wayne Keith
Wayne Keith's picture
Hello Henry,

Hello Henry,

The temp gauges I use are oval and should have been under ten bucks.

Henry Austin
Henry Austin's picture
Thanks Wayne, those are the

Thanks Wayne, those are the ones I have.

Carl Zinn
Carl Zinn's picture
I wondered if there is a need

I wondered if there is a need to install a fuel/air ratio kit, or something like that, to help evaluate the performance??
cz

Chris Saenz
Chris Saenz's picture
Yes, Wayne has a narrowband

Yes, Wayne has a narrowband O2 sensor with an AFR gauge in the dashboard. Even better would be a wideband sensor with gauge, they are more precise and read accurately at ratios other than 14:1.

Premium members, check out the new instrumentation page over here: http://driveonwood.com/premium/instrumentation

Henry Austin
Henry Austin's picture
Sean,

I got motivated to think on the temp probes today,.. I guess I need some more info here'

You are using probes rated for 2100F, I first found some rated up to 2300F, but I thought i read somewhere that the internals of the unit (combustion zone specifically) reached higher temps. Do we know what the highest expected temp reading in a WK style gasifier is?

It looks like the absolute highest thermocouples available are rated for 1600C which is 2900F, this should definitely hold up. I found this while searching around;

http://thermocouple-online.com/thermocouple-T4.html

What is interesting about these is that they have a 4-20ma transmitter option - meaning they will connect to the much less expensive analog input cards as opposed to thermocouple input cards (GE PLC). - Sean, can you get your units with a 4-20ma transmitter?

Here's their ordering guide for this thermocouple;

http://thermocouple-online.com/pdf/pages/095.pdf

What are your thoughts Sean?

Sean French
Sean French's picture
Hi Henry,

Hi Henry,
So far this looks really good. I haven't tried Alumina yet currently working with Inconel and having trouble free results. The two probes on my f-150 were on my old red truck as well so over 20,000miles total on them now.
I would be interested to see what there pricing looks like. Current temps at the nozzle field at this time are not known. If I were going to measure this I would make sure the probe could handle at least 4000 f I can get these but your probably not going to like the price. Toss a nail in the gasifier and it will come back through the grate. toss a bottle cap or aluminum can in there and your never see it again. I will ask on Monday about the transmitters. Regards Sean

Henry Austin
Henry Austin's picture
I was re-reading Chris's post

I was re-reading Chris's post about the AFR gauge Wayne uses. I found this wideband sensor/gauge kit;

Autometer 4378 on ebay at:

http://www.ebay.com/itm/Auto-Meter-4378-Ultra-Lite-Wideband-10-1-to-20-1...

What I like about this kit isn't the price ($289.76 - haven't price checked elsewhere yet) but this;

"Gauge has a 0-4 volt output data port that can be used for data acquisition, to connect to an ECU, or for custom tuning on your laptop."

If this is a straight up linear 0-4V output, this could also be routed to the PLC's analog input card. This would allow us to create a Fuel ratio subroutine that controls the air/fuel mixture for us on the fly!

Thoughts?

Sean French
Sean French's picture
I like the product but we can

I like the product but we can do much better on the price. Try searching. Aem wideband gauge on eBay I use the analog dial version price should be 100 125 dollars at most

Chris Saenz
Chris Saenz's picture
I think the wideband sensor

I think the wideband sensor output a linear voltage from 0-5 volts, you could get a simple voltmeter and translate the voltage into the desired ratio.

Henry Austin
Henry Austin's picture
Agreed, that price is too

Agreed, that price is too high. I found several alternatives using that search. I am now interested in this one, and at $199.80 it is not only less expensive, it also has slightly better output resolution (0-5V instead of 0-4V); Great tip man!

http://www.ebay.com/itm/AEM-Wideband-O2-Air-Fuel-UEGO-Gauge-Kit-/1905052...

As I begin to think about the instrumentation package, I am a bit torn conceptually on what is best. One of our core philosophies in the switchgear industry is to always have a backup. When you automate something, you always include a manual backup in case the cpu, plc, or whatever other component you are using dies. Many of the sensors, transducers, etc I am considering can be directly wired into the PLC without the need for further gauges, and in some cases it is more cost effective to then have the plc drive an analog gauge when one is desired, however I like the idea of also having the actual gauge to look at, just in case the plc does fail (they rarely fail, but it has been known to happen). I think my design concept will be to have (unless it is absolutely impossible) all measurement devices feed the PLC, with the ability to function independently if the PLC fails, or where this is not possible to have a second external device provide redundant indication. The automated bells and whistles are nice, really nice - BUT at the end of the day you must be able to use your ride, even if the toys aren't functioning properly.

Also, being sorta old school I just really like an analog gauge, it's a lot easier for your mind to interpret the needle moving across a dial scale than it is for it to interpret digital numbers on a screen this was the first thing I learned when trying to parallel multiple generators.

Henry Austin
Henry Austin's picture
Chris,

Believe it or not this is exactly what a large portion of our industrial metering was! You would take a voltmeter or an ammeter and then provide a scale plate labeled for whatever you were metering. Old school but it definitely works, and it is very simple.

Unfortunately both of the above kits drive the voltage output from within the gauge. It looks like the wideband sensors provide a 0.45V RAW output (from sensor to gauge), meaning if we just wanted to save some $$$ by buying the sensor for $45 we would have to develop a home-brew transducer to generate a usable voltage or current output (this voltage is too low for the PLC and most voltmeters to read). Or we could buy one kit, open up the gauge and see if we can reverse engineer it, it's probably a pretty simple PCB. This could become a huge cost saver if we all start using them...Then I found this;

0-1V to 4-20ma converter schematic; (Feeds signal to PLC or other micro-controller)

http://schematics.dapj.com/2005/10/0-1v-to-4-20-ma-converter.html

Couple it with something like this; (provides a gauge for us humans to look at)

http://schematics.dapj.com/

This site has several useful schematics for those with the skill/knowledge to build their own PCB's. If we devoted the time to design the PCB there are many companies that will manufacture them for you at very low cost, sometimes less than $10 / PCB though they almost all have minimum runs. If there was significant interest in going this route, I might be willing to devote the time necessary to develop a master PCB for woodgas use - after all required and desired metering is determined (no sense in making multiple small PCB's). I wouldn't mind one that connected to all the sensors, probes, transducers etc and provided voltage outputs for gauges and 4-20ma outputs for automation, that would be pretty slick!

Although at $199 for the gauge, the sensor, the wiring harness, and the ability to drive a PLC (if desired) the AEM looks like a pretty decent value. Laziness is likely to get the best of me here!

Chris Saenz
Chris Saenz's picture
OK, I spent a little time

OK, I spent a little time reading up on wideband sensors and narrowband sensors, and why thye always have controllers for wideband. This is what I came up with:

  • The narrow band sensors give off a voltage potential between 0 and 1 volts. Basically flipflop from one voltage to the other, to tell the computer "rich/lean". Computer is constantly flip flopping the sensor to try and ride the edge.
  • The wideband sensors take this a step further. They add an oxygen pump to the narrowband sensor, and add a small amount of oxygen to make the narrowband part stay right on the line. The current required to drive this oxygen pump varies linearly with the AFR of the exhaust gas. So we have gone from interpreting voltage to measuring current. This is where you need a controller. It has to run the oxygen pump at the right speed to balance the narrowband part, while converting the current measurement into a usable signal for the gauge/ECU. These controllers are set up to output 0-5 volts. You could then display the voltage result on any analog meter or gauge.

Summary: narrowband measures voltage 0-1v, wideband measures current and the controller outputs voltage 0-5v.

Those expensive gauges have a controller built in, there are other controllers that are inline between the gauge and sensor. Innovate makes the LC-1 and LM-1 which are inline. Pretty pricey even there.

I am familiar with the Arduino PLC platform, it may be possible to write a program to run the whole shebang and output to a cheap display or voltmeter. The chip is $4, depending on what you need with it development kits run $70 or so.

Wayne Keith
Wayne Keith's picture
Fuel/air

Fuel/air

If one has loud mufflers he can set the fuel/air ratio by the sound of the motor but if the vehicle is quite the fuel/air ratio gauge really helps.

Once the gasifier has warmed up you should be able to drive out a hopper of fuel without readjusting.

I filmed this short clip just at daylight this morning.

http://youtu.be/imP0oxzldQI

Chris Saenz
Chris Saenz's picture
Wayne,

Wayne,
You got it going on! I did notice that even as slowly as you were adjusting it, things jumped from lean all the way to rich very fast. I think you just demonstrated the problem with narrowband sensors, they are very sensitive in a narrow range, but not in the range that we need. Not that they can't be used, but that's why manufacturers are moving to wideband and why we should do the same.

Henry,
Check out this link: http://www.megamanual.com/PWC/

Carl Zinn
Carl Zinn's picture
Excellent Wayne. What kind of

Excellent Wayne. What kind of O2 "kit" did you install? I'm assuming you poked the probe into the exhaust, (I wonder where), and ran some wire. 2 wire, 3 wire or 4??

cz

Sean French
Sean French's picture
This is great you all are

This is great you all are making some real headway on this subject. Henry that's the same gauge I use keep searching you might be able to find it even cheaper. I will look when I get a min. I can't get away with loud mufflers in my neighborhood so these have been a real help. Make sure you install the sesnor pre cat converter or you won't get good readings Regards Sean

P.S. This is the link to the same setup I have and it is also the one I would recommend notice the number scale goes from 8-18 8 rich 18 lean make sure your gauge has a wide scale range on it stay away from the ones marked e85 the price has gone up a bit since my last build

http://www.ebay.com/itm/AEM-UEGO-WIDEBAND-O2-SENSOR-OXYGEN-AIR-FUEL-GAUG...

Terry Grzyb
Terry Grzyb's picture
I find nothing wrong with the

I find nothing wrong with the narrow band. The only range they display is the range you want he engine to be running in anyway. I don't need to know how far out of adjustment the mixture is.
T

Bruce French
Narrow band gauges use LED

Narrow band gauges use LED lights and if the mixture moves fast one way or the other and the driver misses the move, then confusion sets in. Once the extremes are hit the LED lights no longer light up. The analog gauge never confuses. I have tried both and would not use an LED gauge again. On the narrow band gauge the lean mark is no where the true lean mixture the truck can run on.

Terry Grzyb
Terry Grzyb's picture
I agree Woody, LED's would be

I agree Woody, LED's would be harder to follow. I have a dial face narrow band, no problem reading it.

Bruce French
Who is the gauge made by?

Who is the gauge made by? What O2 sensor are you using?

Wayne Keith
Wayne Keith's picture
Hello Carl,

Hello Carl,

I have been using the cheaper brands (about $30).

There is a hot wire, ground wire and a third wire that connects to the wire coming out of the computer that runs to the 02 censer.

Terry Grzyb
Terry Grzyb's picture
Here are all my monitoring

Here are all my monitoring gauges Woody.
2 manometers, temp and AFR.(piggy back stock O2)
By the way, the thermocouple is 1" down from the restriction. It runs through the hopper where it shorted out from the moisture. When it was running, it would have the dial pegged. So of course I no longer use it. Someday I may hook it up to the grate.

Terry

link to gauges http://www.amazon.com/GlowShift-White-Color-Needle-Ratio/dp/B007K8MU08/r...

Bruce French
Thanks Terry. That's the

Thanks Terry. That's the first analog air to fuel mixture gauge I've seen. So you hooked it up to the factory O2 sensor? If so, that's neat and very good setup imo.

Drove 50 miles on wood yesterday and the wood is soaked now. It never gets a chance to dry out with 96% humidity and 5 inches of rain over night. I keep a stack of 2x4 scraps in the garage to keep dry for start ups.

I had nearly the same problem with my first thermocouples. The acid from the wood gas ate up the wire and started giving all kinds of weird readings. The shielded one has lasted almost 10 months now and still looks OK.

Terry Grzyb
Terry Grzyb's picture
Yes, it's connected to the

Yes, it's connected to the stock sensor.

If I had as much rain as you guys, I think I would have to monitor those temps pretty closely. We all do what we need to get by.

My thermocouple has the ceramic blocks/separators. It is not sealed from the environment so hopper sludge was able to short it out.

Bruce French
The gasifier killer on this

The gasifier killer on this end was the heavy loads we were trying to pull. The wet wood hasn't been a problem. We have several different ways of dealing with the wet stuff. In the Ranger if I load the bed up with wood the thing heats up more than when empty. There are times when heat makes more of a difference depending on the state of the gasifier.

Brent Wolf
Brent Wolf's picture
sean, have you ever thought

sean, have you ever thought of trying to use oxygen sensors as a "crude and cheap" way of measuring gasifier operation, i believe since you have a wealth of thermocouples you could observe changes in temperature and compare to O2 sensor readings, they might be able to be pretty close to the burner, cooling rack, or after the hay filter, i think if it were to work it could be a cheap alternative means of instrumentation, but i can see them getting plugged easily, since woodgas isnt engine exhaust,

just a thought

Sean French
Sean French's picture
Brent

Brent
I think that measuring the gasifier temp is extremely important. And the probes and displays I use are dead on accurate well worth the money for what your getting. I have used these same probes for years now they never fail. Do you know something about o2 sensors I don't because as far as I know they don't respond to heat only flammables. Below is a test to see if a sensor is bad or not. Sean

http://www.youtube.com/watch?v=1mb4VmDd0ao

Brent Wolf
Brent Wolf's picture
i actually dont know a lot

i actually dont know a lot about them, and yes im sure having a accurate and precise (those are two very different adjectives) temp reading is the best you can get, if O2 sensors are looking for a varying amount of O2 (not sure of this but the name implies this), i would hypothesize that the O2 levels would increase as a gasifier was running low on fuel, i figured since you have a very good feel for your equipment, and have watched it perform over and over again that adding an O2 sensor and comparing its readings with your gasifiers usual behavior and the actual temp readings that you might be able to see trends between the O2 sensor readings and your temp readings, the only reason i ask or suggest is bc i have a bunch of those laying around and i know they work, and im a budget minded individual, anything i can get for free ill take it, and i was thinking about how i would go about instrumenting my unit, bc i dont want to melt the thing down out in the middle of nowhere or something, ill look into this more, i just figured since they are used in exhaust applications they could take the heat, and even soot/tar, but i think it could be likely they would gumm up after a few thousand miles

Sean French
Sean French's picture
Brent

Brent
Yes your are on the right thinking path however the temps will rise instantly as soon as the unit runs out of fuel. The next will be weak gas at this point the temps are already to hot and risk damaging the unit. So I wouldn't try or rely on it next the o2 sensor in the gas stream is not going to hold up over time it will carbon up and you will constantly be cleaning it. My probes tell me lots of information not just out of fuel. Also overall gasifier conditions and leaks in the system. More on this later
if you want to experiment there is nothing wrong with that if you want something that is tried tested and proved the probes are here for you. It comes down to how much is your time worth to you. Sean

Brent Wolf
Brent Wolf's picture
yea i watched the video,

yea i watched the video, thats neat and i didnt know that, and yea i bet they do gum up, if you had to pick a basic and reliable set of thermocouples, and their locations in a standard burner+cyclone+cooler+filter unit and their temp ranges what would you suggest? just me thinking again i would say one right around the grate area and right around the entrance to the cooling rack, do you think reliable operation from those two thermocouple locations and a few vacuum guages between systems would give the user enough information to run with out too much worry? also what temp ranges for the needed locations? you said earlier 4000deg f for the burner area and then maybe like a 100-600 deg f for the cooling rack area?

Richard "Pepe" ...
Richard "Pepe" Lemieux's picture
Hi Brent,

Hi Brent,
We were asked in a machine design class, "What's the difference between precision and accuracy?". Lots of puzzled looks including mine. Suppose a program is set to drill a series of holes in a plate. Precision is drilling every hole in the exact same place every time. Accuracy is making sure those that those holes are located in the correct location in reference to the plate.
I'm at a point where I want to monitor temps in my gasifier so this is great info for me, but you are technically heads and tails above me, but the monitoring is fascinating. I'm at the beginner laser pointer level and not sure if that's worthwhile information.
That's a sharp looking PU.
Pepe

Brent Wolf
Brent Wolf's picture
thanks pepe, i always

thanks pepe, i always remember by thinking about rulers, where the distance between the hash marks being as close to equal as possible determining the precision of the tool, and then if you measure an inch with this ruler and it is infact an actual inch then the tool would be considered accurate, yes your analogy is right on, and thanks about my truck!

Steve Unruh
Steve Unruh's picture
Hi Guys

Hi Guys
Yes O2 sensors do measure the "Remaining" oxygen in an exhaust stream. Narrow band type only designed as a feed back sensor around a very narrow range.The single wire (two wire and some three wire) snesors do this outputting a variable self made voltage signal from the inside of a ceramic tube closed end tube exposed to the outside air versus outside of the tube exposed to the exhaust gases. The tube surfaces are coated with rare metals. This style has to be heated to work and yes is easily contaminated from either side of the tube.
The wide band types can be either be in external testing instruments or exhaust stream mounted. Tney are ussally designed to measure oxygen from zero to ~22%. To do this they are always self heater heated, and most use an oxegen changing variable resistance element tech. So they must have an outside power supply for the heater element, a very precice fixed input voltage or amperage external supply. Measurement changes are in monitoring circuit voltage or amperage changes created by the oxegen present changed sensor resistance. They are also easily contaminated. A lot more electronics involved and software logic in these.

Varying pulse width tech can also be used. These have always had a very high in field failure rate. Lab rat stuff.

Temp monitoring is much more reliable and direct and durable for the operating conditions. Pressure monitoring good outside the core hot zones.

Regards
Steve Unruh

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