Vac kiln for Costa Rica

[Den Socling]

Suppose we put the painted side toward the sun and a condenser on the other side. The wood would be stickered. Maybe we could control drying with humidity control. Maybe an alarm could pull lower chamber pressure if the wood got too warm. At night or anytime the painted side got too cool, the vac would shut down and the wood would equalize. What do you think, Sergey?

[serg]

Den, hi!
I think that this system will give positive result in heating.
Qualitative movement of air will not be. There will be a mould, the big difference on a stack.
What temperature in the afternoon in CR?
Sergey.

[Fla._Deadheader]

 HEY, A personal thread. 

  CR does not get above 80 degrees for very long each day, and that is just a few months of the year. The tank could be shaded some, if needed ??

[serg]

My opinion. In CR it is necessary to use a solar energy. I offer to heat water and to submit her(it) to registers. It is possible to strengthen heating of water due to mirrors. Cooling at night, the big pause, a stack will cool down strongly. In the afternoon energy will be directed on warming up of a stack. Drying will receive zero variant.
Stack to warm up, more energy is required 2-3 times.
Conclusion. It is possible to use the combined system of heating, in the afternoon the sun, at night maintenance with the help of the electric boiler. The tank should be warmed well. A pause of cooling of 20 minutes. My vacuum drying chamber works in Uzbekistan. Temperature in the summer of 45-50 degrees С. Economy of an electricity big.
Sergey.

[crtreedude]

Thanks for the help everyone - a little data here.

The temperature is variable in Costa Rica based on the altitude. Where Harold is, 82F would be warm - but, and it is a big one - the sun is direct. You won't believe how strong the sun is unless you have been in the tropics before. On the low lands (like the other farm Harold), it will get warmer - say 85 F.

When the sun is out, things heat up - it is just you only have 12 hours of sunlight year round. Doesn't really get cold at night either. If it rains the day before, when the sun shines, it can feel like a sauna. Harold hasn't experienced this yet.

The hot time of day is from 10:00 am to about 3:00 pm.  It is never like in the North in the Summer though. But that is ambient heat - not solar heat.

The solar heat is more intense - but the ambient heat is less due to the cooling during the night.

Oh, and electricity is very cheap here.

[Den Socling]

Sergey,

I'm thinking of this kiln as a steam vac. We leave enough air and vapor for natural convection. Since the location is so close to the equator, the sun is more directly overhead so one side might be painted black and the other side would be white or shaded.



Halfway up the shaded side would be a kiln condenser similar to this to cool and dry vapor that was rising on the black side. We would need to add a baffle under the cart. Air would flow through the stickered wood.

If the steel got too hot, we would pull the chamber pressure lower. This would interrupt the transfer to the wood and, since we lowered the boiling point, the wood would cool while a lot of water was removed.

If the wood started getting too cool, we would let the pressure back up and recover more heat.

Just thinking out loud, here. 

Den

[crtreedude]

Remember also labor is inexpensive - within reason, having someone move shading material on and off the vacuum might work fine. Just another chore to do on the farm - check temperature gauge and adjust shading.

If we can automate it - that is fine, but people will be around all the time - and they have no problem reading a guage.

[serg]

Den I with you agree. A solar energy to use in vacuum it is possible. You perfectly know that it is necessary to make: 45 degrees С, vacuum 0.09, plus movement of air through a stack. Can it is necessary apply the fan to good and fast heating switch off the fan and collect a condensate. Work behind experiment.
Sergey.

[Fla._Deadheader]

Anyone ever see an Autoclave ??  A BIG one Found one today, that is 50'' dia. X 24 feet long. Doors on both ends. Has a control box with needle type recorder. Has a track inside and 2 pipes, about 1'' dia., running the length of the tank, overhead. These have small holes, presumably to emit steam ?? Comes with 2 ball valves, one SS, one Bronze, probably 2? pipe. Many small pipes on the top outside, running the length of the tank.  Seals are Asbestos. Has insulation that can be removed if necessary.

  Questions

[Fla._Deadheader]

 Can I get a rough time schedule for drying one load in this kiln, if all goes well ??  Forgot the time frame involved. ?? It's all Hardwood.

[serg]

Fla, hi!
I understand (the computer translator not absolutely correctly a little translates) you want to do (make) independently vacuum furnace? You want to dry what wood? Breed, density, thickness and humidity?? Capacity square or round. All begins with calculations of durability on residual pressure (-1) from an atmosphere. What technology of vacuum drying?
You do (make) technology CR? To give advice (councils) on a forum, knowing half essence of a question, not correctly and dangerously.
Sergey.

[Fla._Deadheader]

Hi Sergey
 Trying to build a kiln to dry tropical hardwoods. I do not have exact information to answer your questions. I understand the problem with answering without all the required information.  I was just asking a rough guess, referencing from past experience of Oak. I will be away from the Internet very soon, and will need crtreedude to obtain the information for us.  Thanks for any and all assistance you offer. It is greatly appreciated.

[serg]

Well.
I shall wait with the big interest the information from you.
Density of an oak in Russia 690 - 720 kg/ М3, density of exotic breeds from 900 up to 1200 kg / m3. Term of drying will increase in 2 times.
Sergey.

[Den Socling]

Harold,

We will be able to give you some idea after you have run a few loads.    You are entering uncharted waters! The only thing I might guess is that it will be faster than a conventional kiln depending on how late into the evening we might have enough heat to keep it going.

A better idea would to be to use an auxiliary heat source during the night. Copper pipe running back and forth on the inside bottom of the black half ought to keep the convection going.

It's surely going to be faster than air drying. And the wood is much safer in a steel chamber.

Den

[Tom]

May I interrupt for a question?

Here is my observation:

The heat from the sun is derived in intensity by the directness of the rays.   Summer gets them coming straight down and winter gets them coming at an angle.  The direct rays provide more energy.

The temperature in CR being 80 degrees is because of ocean breezes and altitude.  Ocean breezes evaporate perspiration and  make you feel cool, but a solar collector (not affected by wind) will get real hot.  Altitude is cold because there is not as much air to heat.  The suns rays are the same as at sea level though and a collector should generate as much heat in either place.

So, the cooling of a kiln at night could be controlled by insulation and Mass (serg's water)

Here is the question (assuming the above to be correct)

Wouldn't  CR be an ideal place for solar collection because of the direction of the rays, regardless of ambient air temperatures?  And, why would ambient air temperatures, controlled by insulation, be much of a concern?

[Murf]

As a follow up to Tom's observation......

Wouldn't it be relatively simple to use a large tank of liquid as a thermal storage unit?

Use the heat of the sun durning the day to heat the liquid, and kiln, then all night draw the stored heat back out of the liquid and into the kiln. That way you could achieve a much more uniform heat.

The other point, if it's of any use, I would be more than willing to offer English / Russian translation if it would make the process any easier. 

[Den Socling]

The auxiliary heat could certainly be from water that was heated by the sun during the day. Then it gets pumped through the copper pipes I mentioned. There is a greater danger of overheating during the day. He needs a vac system capable of forcing the boiling point down.

[old3dogg]

I would have a back up heat source because the sun is just not reliable enough.

I feel that while vac drying you need to have constant heat. What if you get weird weather and the sun doesnt come out for 6 days?

Id be afraid of a solar powered vac kiln.

I wish you luck and maybe it will work but vacuum drying only works well if you are stacking wood between hot water plates. Unless of course you are drying thin wood. But then again, whats the point of a vac kiln?

Steam, solar or DH will work on thin wood. And much cheaper also!

[crtreedude]

It is here except for about 2 weeks out of the whole year. Clear almost every morning - about 4:00 PM get a rain of about an hour.

Then, during the time you harvest most of the wood - no rain at all for 3 months just about.

I wouldn't worry about lack of sun.

[old3dogg]

Still dont think it would it work. The weather just aint reliable enough.
Ya must have constant heat to vac dry. And a constant vaccum.
Cant start and stop. It just doesnt work in vac drying.

[Den Socling]

Mike,

How you been?  Hear you do service at L&H.

You can start and stop if some parts aren't left out of the starting and stopping. It won't be anywhere as near as fast as one of our kilns but these folks don't want to spend $150K. Do you Harold? 

And I kind of like the idea of developing a low tech, low cost vac kiln for the guys who are willing to go 'relatively' slow.

Den

[Fla._Deadheader]

 Shoot Den. I don't mind spending that money. It's Fred's. 

[crtreedude]

Since most of the time, there will not be an issue - the other times will not be a problem.

There is a difference between optimal performance, and adequate. As long as the quality of the wood is fine, even if it takes a few more days, it really isn't that important.

$150 thousand might be a good idea in the future if it was production ready and we needed the volume. Right now, it would require us to be ready to keep it fed, or it would be a bad investment.

No point having a dump truck with a backhole when you are just digging a garden. Once we get running, it is another matter.

Then again, a row of solar kilns might make more sense.

[Den Socling]

I saw a show on TV the other night that featured the capabilities of the fer-de-lance. 

I ain't makin' no service calls in CR! 

[old3dogg]

I have seen the affects of start, stop, start, stop in vacuum drying. It cracks wood.

I dont blame Harold and Fred for wanting to use the sun. Sounds like an endless energy source down there. If I were them I would feel better if I had a back up heat sorce for my kiln.

I would love to see these guys get this kiln going.

Den,
I go into L&H once a month to test the water for them. Not a lot of work because they do a great job in keeping it treated. Havent bio fouled the towers since Ive been going in there. The corrosion rates have been good also. No easy feat considering the hardness of thier well water and the acidity of the water in hard wood! They do seem to rot out a lot of shells on the heat exchangers. We figure that is due to the amount of Maple they dry.

I also go down to K & F Wood and we still have BWP. The water treatment at BWP has always been a night mare!

[kurtis]

Hi Fred,

We have talked about tatf in the past. FYI I thought I would comment that when I was in CR, I walked their solar drier and walked through a significant portion of the thinning lumber processing. All their drying of thinning (that I saw at least) is very low tech-all solar and air dried. The lumber waiting to go into the solar drier(s) was stacked and covered at the top. Rightly or wrongly I came to the conclusion that the lumber product (from early thinnings) was just not high enough $$ to go any higher tech and justify additional $. That as well as I do think Tatf only can use so much of the thinned lumber at a time and they were happy to process it at the current rate.

Also it appears that they are way behind in payments to tree owners for the thinned product in general and have recently been tagged for not paying social security payments on their employees. This much has been confirmed by an email that I received from the company. They, of course, are moving to correct these things, but I get the feeling that there may be more to the iceberg based on my experiences with them.

[Den Socling]

Mike,

I have one of those red, yellow, green stack lights on my kiln. This afternoon, I noticed the red light was on. That means the PLC shut it down because it 'thought' something was dangerously wrong. I walked over to see what the problem was and it said 'cooling water circulation failure'. that means 'clogged strainer'. Know what I did? nothing. I was busy and I'll clean the strainer tomorrow and then restart the kiln. It doesn't hurt a thing because drying was perfectly under control and drying conditions gently went/are going away.

I'd like to see a low-tech vacuum kiln for the tropics, too.

Most or all of the corrosion at L&H occurred about 5 or 6 years ago. I warned them every week or two that SRB's were getting their foot in the door. They just didn't understand the threat until it was too late.

Den

I heard the presumed correlation between maple and corrosion. I don't buy it. SUNY is doing a chemical analysis of HM juice - doing a study on converting wood sugar to ethanol. I'll double check for corrosives but I know they are minor compared to oak.

[Larry]

Oh, and electricity is very cheap here.

Sounds like time for a Nyle if you guys are serious and want to do it on a small investment. 

[old3dogg]

The corrosion rates are higher when drying maple because of the faster drying rate and L & H,s exchangers are way under sized.

Red Oak is much, much more acidic however, the drying rate is a lot slower so the exchangers can keep up. Gas is turned back to liquid at a much slower rate.

Would it be possible to make a shell and tube out of SS, copper and brass?

[crtreedude]

kurtis,

We are about 3 years away from thinnings - and I can sell everyone today if I had them. TATF is in a different part of the country, their wood grows slower (perhaps this will create a harder wood - hard to say) but because of this the size of their first thinning is much smaller. We of course have the advantage of coming after them and structuring differently. They planted more trees per hectare than we did - therefore, their first thinning has less value.

Regarding their financial problems - did you see Steve's response? The amount they are behind in taxes is only 1% of their asset base - not a big thing.  Oh, and here, being behind in taxes is not as serious as there - you only have to pay 2% per month (that that is on colones that devalue 10% a year) on the outstanding amount. We were 3 months behind on the CAJA - not deliberately, just the challenge of doing business in a foreign country with a clueless (since replaced) accountant.

TATF in a way would be considered a competitor of ours, but, except for them possibly being behind on paying tree owners, I have heard nothing that bothers me, or is just the fun of doing business.

TATF is behind 200,000 dollars - that sounds like a lot until you realize they have 500 employees if I remember correctly... I estimate that that is a payroll of 1 MILLION a year. It doesn't take long to get behind in the CAJA when you have that size of payroll.

The kiln is probably not for teak thinnings - it will be for other types of wood. But, it could easily be for the the teak thinnings too. 70% of our wood will probably be sold green - I can get 2 dollars a board foot for green teak thinnings all day long. They use it for construction here - and they use it green too. If you want to see an example, I can show you our house on the first finca. Perhaps Harold would like to comment on it. We put in 6x6 teak beams (12 of them) around the porch - green. 8 months later, they look great. The only problem is that we created a fashion in homes now in the area and everyone keeps buying the teak around us for building homes!

Just my comment regarding tree growers, I had an interesting converstation with a forestry engineer here with 20 years experience. Our discussion centered around this: Most of the tree growers out there do not realize that they are focusing on the wrong thing - growing trees. You have to focus on growing lumber, not trees. Trees will grow without you doing much at all - just leave the land fallow and trees will eventually grow - but lumber is a different thing.

Too often, when the people need to harvest their trees - they then find out selling trees for a good price isn't as easy as it sounds if you don't have a market. We are about 3 years away from our first thinning - but I am building the lumber company now. That is because I will have the demand and the shipping in place first. We are already buying wood from other plantation owners and selling it.

It seemed obvious to me that most of the money was being made by the processors and the sellers of wood - therefore that is where we are. We grow trees as a guarantee to have a source of good trees in the future. Costa Rica is projecting to have to start importing wood in 3 years. 

Unfortunately, much of the problem is that the majority of the teak planted here is poor quality because it is full of knots (and I can sell that that too - but for less) because people felt they were growing trees - not lumber.

The wood situation is getting tight enough here that people are cutting down fence post (which grow here) when then get big enough to use the wood for concrete forms. We get 50 cents a board foot for junk wood used for concrete forms.

By the way - someone forwarded me both the original and Steve's response (owner TATF) when it first  came out and Steve said that anyone could forward his response. If anyone wants to see it - I can post it.

[crtreedude]

Interject something into this - it might or might not be right.

I am an engineer by trade - software and also hardware. I am from a family of electrical engineers. This doesn't mean much regarding vacuum kilns, just a little background.

I appreciate calculations - but I have been around long enough to know that you build a system that can be "tweaked" - the great lie out there is that anything is designed directly - nope, it is adjusted. And then, people take the adjusted, look it over, and say - "you know, if you did this and that, you just might have something" They try it, and sometimes it works, sometimes it doesn't

I think we have found the tank for a very reasonable price - next is to get it built of course. Step by step.

old3dogg - I suspect we will make a backup source of heat - probably some kind of boiler that takes wood is my thinking - after all, we will probably have enough scrap around to fire any number of boilers.

What is going to be "fun" is that there are 150 different types of wood here... Thankfully, they are much more stable that wood in the north. We will probably have a situation where we start off getting most of the water out in the field - stack them in the shade for a month - and then we move them for final drying with the kiln - per order. Furniture makers targeting Northern markets will be the ones who want the wood from the kiln.

But for the rest - it just isn't an issue - air dry is fine. The wood in the walls of homes here is about 18 to 20 % - we are in a rainforest climate after all...

[Den Socling]

Mike,

L&H is running old and relatively slow schedules that I wrote 5 or 6 years ago. There's not a big difference in the amount of time they spend in drying different species. The schedules vary mostly by thickness. But lets suppose that they dried maple in 5 days and oak in 7 days. Suppose the oak starts at 70% and the maple starts at 80%. You would think that the pump condensers really get hit while drying the maple, right? Wrong. There's more water in the oak. If you dry 1000 bf from 70% to 6% in 7 days, you move 1.8 gallons per hour. And a 1000 bf of maple drying from 80% to 6% in 5 days works out to 1.6% per hour.

But it makes me wonder if a kiln in CR needs a chiller.

Den

[old3dogg]

Den,

Maybe it is not how fast they are drying but how much?

I do see a big difference in corrosion rates between Maple and Red Oak. Maple has a higher rate of corrosion.

CR will need cold water for the vac pump and heat exchanger.

I never did a study with the corrosin coupons at BWP. Maybe I should have. I will have to see if we still have the reports from the last few years. I dont know what they would tell me but you never know. I know that they are using pure soft water in the hot water boiler with out an inhibitor and are chewing up their heating plates. Plain old soft water is murder on aluminum.

[crtreedude]

No problem on cold water - gazillion springs here. (one farm has 7, the other 4)

As long as it is only pass through (no pollution) - it won't be an issue.

[old3dogg]

Single pass does work best and since you are only planning one kiln you shouldnt have to recycle your water.

I had 8 vac kilns and 3 RF/V kilns so I needed lots and lots of cold water!

Cant remember the true number but I think we would push something like 10,000 gpm through our system. If you reuse it you have to treat it.

[Den Socling]

Mike,

Your cooling tower pumps were 1050 gpm each.

Fred,

What's the temperature of spring water in CR?

Den

[old3dogg]

The water coming out of wood is considered pollution here in the states. This is due to the very low PH. I had to treat the waste water with caustic soda to keep the PH level above 6.5. Anything below that is acid and if allowed to flow into streams it could kill fish.
However, you are only talking about one kiln so I dont see a problem.

[GaS]

their single pass of spring water through the condenser and vac pump should come out nearly pure (maybe some vapor making it past the condenser into the pump, but not much)

the condensed water out of the kiln, like you say, is a completely different story

[kurtis]

Fred,

Just a retorical question or two then I will stop polluting the thread with teak/TATF stuff.

If you can easily get 2.00/bd ft for green teak thinnings, why doesn't tatf offer that as an alternative to their tree owners for the early first and second thinnings? I am sure that at least the second thinnings are large enough. Also the quickest way to have owners loose faith is to not make distributions in  timely manner.

Yes, I have the email from Steve, but frankly, it just increased concerns on my part. How does someone control and/or run a business when they do not take an active role in the management of the place. Steve is an attorney and how do you run a business and not pay social security taxes for 3 years? This says to me that he has lost touch with operations. Who exactly am I doing business with? After all, the buck stops with the owners and the email from Steve did and said everything except that he takes responsibility...

I have more comments as usual but will save them for a more appropriate thread and time.

[crtreedude]

No idea why he doesn't offer that to his tree owners. But, he won't make money at 2.00 a BF - since that is what it is sold as. Just some basic math if you wish.

Price of teak stumpage 100 to 200 colones per BF (500 colones per dollar - so, figure 20 to 40 cents.) Of course, the 40 is for good wood. I have heard as high as 1.25 BF for older teak (20+ years) and there is some here, but it is rare.

The price at the sawmill for good teak - between 80 cents to 1.00. This is what our tree owners will be getting (adjusted upward for increase in value of wood, etc.) and they make their numbers. We make the money above that for the markets for value added processing.

This treats teak not as "the king of the trees" but as a very good quality lumber that is resistant to insects.

Yes, Steve is responsible for whatever his people do. Where did you see that it had been three years? With his payroll - I doubt it would take that long to get behind.

As far as I know, Steve was out trying to market RALEO - their furniture company. This was their plan on how to make money for the tree owners. He trusted someone else to be watching over the factory - this is normal. He wasn't paranoid enough - this is also normal.

If you would like the official average prices for wood in Costa Rica - I can send it to you.  It is from Directorio Forestal de la Oficina Nacional Forestal, 2005

I am honestly trying to be fair with TATF - I have no desire to beat my chest and say "Look and them - aren't I better!"  But, it isn't my job to defend them, or their business.

On the international markets - you can get a better price - but you have to have distribution set up.

[crtreedude]

Oh, and one thing perhaps different with us - if you want to look at our books - we have a policy of releasing them to anyone who is interested in what we are doing.

And I agree - I check everything, all the time. But then again, I am paranoid.

[Den Socling]

As convoluted threads go, this one takes the cake. 

Mike, 
The new shell and tube heat exchangers are are all brass and copper. SS doesn't conduct heat very well.
Den

Harold,
Did you end up with the autoclave? To have a sealed door is a leap forward.
Den

[kurtis]

Fred,

Wow? Open books! This is unparalleled. Steve and TATF (as you know) won't disclose any information about nearly anything.

Again, if the company is yours, I agree, you need to be paranoid.

One clarification: as I understand things, TATF is suggesting that they will find a market for the thinned teak (through Raleo) at 2.51/bd ft for the early thinnings. They do eventually take 6% for harvesting costs.

Someday I will be back in CR and will swing by for a day. We have not been to the north yet.


[float=left][/float]

Oh, and one thing perhaps different with us - if you want to look at our books - we have a policy of releasing them to anyone who is interested in what we are doing.

And I agree - I check everything, all the time. But then again, I am paranoid.

[crtreedude]

Well Kurtis - if I invested in you for 25 years - I would want to know you are financially sound, and were going to stay that way.

More power to him if he can find a buyer at 2.51 / bd - but I suspect that is why he has to get RALEO cranking.  The locals aren't going to buy for that price.

It sure isn't the local market - but at times I can do that with overseas.

I prefer personally to build business plans based on my lowest estimates - not high end. Currently, logs are selling to India for 250 dollars a cubic meter of plantation grown teak. That is almost 59 cents a bf which isn't bad. This has to be well grown trees and at the dock.

Our advantage is our soil and location. If you are in the tree business, you know it is a crop. The better soil, the better the growth. The better the growth, the better the return. We also give it superior care as well.

We would love to have you visit us - perhaps you can keep FDH out of trouble, of course, that might not be a vacation... 

[Fla._Deadheader]

  Hi guys
 Got a little Internet time, so, I will comment. First, Den, Fred and I just recently crossed paths, and we are wanting to get the tank. It is perfect, and won' t take a lot of work to make ready. BOTH ends have sealed doors. 

  We have active springs all over the place here, and I would guess water tempis in the mid 60's.  Doesn't feel like it when you first turn on the shower, but, you get used to it, (numb) real quick.

  Been sawing Beams for Hectors House, then we concentrate on the Lumber Business. We need to get the tank(s), soon and get them ready.

[serg]

These guys from Ukraine do impossible!
What you tell?
Sergey.

[Fla._Deadheader]

  Hi Den
 Fred and I had a good talk, and we are going to proceed with the Vacuum kiln, here in CR. The tank is about a quarter inch thick. It is 50" in dia X 24' long.

  If we can not find a suitable pump here, I will import the pumps we have in Pa. May not be the correct type, but, they are paid for and will at least get us up and going. We can always improve on equipment, once we have a working system.

  Serg's last photo on this tread, shows a lot of tubing running the length of the tank. Is this for hot water or what is the function??  We have constant warm weather here, so, I am thinking about a black painted outer surface, sitting the tank in a sunny place, on a slab of concrete.

 Wheels for the carts. Should they have bushings instead of bearings. Will the vacuum have a negative effect on the sealed bearings ??

[Den Socling]

Hi Harold,

I don't know your tank's design but 24' of 1/4 steel needs some support rings.

Serg's picture shows the heating water pipes that are placed on the bottom and sides to induce a draft. Remember he has the condenser top center and a gap in the load to get air flow. If you want your kiln to heat like his, you need air flow.

Grease is OK at the vacuum that you will be running so bearings are fine.

I'm designing a discontinuous vac for a pole-treating company in the western US. They want to use electric heaters powered by solar cells. It's an interesting project and could parallel yours.
Den

[Fla._Deadheader]

  I will check the tank design. Seems that there IS support rings around the outside of the tank ?? Tank is insulated, and I believe the supports are where the insulation is inserted between them

  I was figuring a Solar Collector to heat water, OR the tank painted Black The Sun is intense here.

[crtreedude]

You know that from experience, eh Harold?

However, you can't count on the sun where we are going to put it - otherwise we would be considering a solar kiln. Most of the time Ciudad Quesada is cloudy. I think we have to consider a secondary heat source.

Also, it gets down to about 65 here at night. We are about 500 feet higher than you are at your place, and very different weather.