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Author Topic: Home made vac kiln  (Read 16413 times)

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Offline Den Socling

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Re: Home made vac kiln
« Reply #100 on: March 18, 2017, 07:28:33 pm »
And I'll add that our vacuum kiln are very easy to operate. You set the final temperature which depends on species and the number of hours you want to spend getting to that temperature which depends on thickness. Then you walk away and come back when it's dry.

Offline serg

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Re: Home made vac kiln
« Reply #101 on: March 19, 2017, 01:08:48 am »
Dan, Hello friends!
Dan I have a question for you. The computer gives the command to move to another level of drying. I put the moisture sensor wood moisture content of wood falls schedule changes the temperature and vacuum. Each Board has a different moisture content on length, thickness. the core of the sapwood. In each Board there is no sensor. Which indicator Your program gives a command to the chart? What is the humidity level of the boards, length, thickness, the final residual humidity in the wood oak?
We have solid wood, African wood, bog oak drying in conventional convective cells do not. This work makes great vacuum drying.
My bad English Dan understands, will give adjustments to the forum to my question.
Sergey.

Offline Den Socling

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Re: Home made vac kiln
« Reply #102 on: March 19, 2017, 10:45:01 am »
Hi Sergey,

In our kilns, A Programmable Logic Controller runs the kiln. We have a computer connected to the PLC for data storage and to provide remote access through the Internet.

You don't want to use a moisture sensor that uses pins. The pins leave a hole in the wood and the wood around the hole will dry faster than the rest of the board because it is exposed to the vacuum.

Our drying schedules are time-based. Many years of experience have taught me how long it should take to dry a certain species or thickness. For example, I know from experience that I need 65'C to achieve a certain MC. I know that the wood will dry at an acceptable rate if I ramp the heat to this final temperature in 144 hours. So I set the final temperature to 65 and the ramp length to 144 hours and that's it. The PLC will smoothly ramp up the temperature and the MC will smoothly come down.

Oh, I forgot to mention the condensate dump cycle. Every time the PLC dumps water that has been condensed from the water vapor that has been remove from the wood, it increments a line on the computer. You can see the the rate that water is being dumped and you can see when the dumping ends.

 

 

In this picture, the drying rate is the black line that starts at the bottom.

Offline serg

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Re: Home made vac kiln
« Reply #103 on: March 19, 2017, 02:15:49 pm »
Dan, thanks for the reply! You and I are from different sides of the globe, I practice vacuum drying, all by doing these two things, You are strong in theory and computer. What I want to say that Your answer coincides with my schedule drying time, temperature, vacuum and final moisture of 1 m3 of oak, the only way to achieve uniform drying . It is important that this work makes a great vacuum drying. We see how much condensate is beyond the entire drying process. Thank You Dan.

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Re: Home made vac kiln
« Reply #104 on: March 19, 2017, 03:15:40 pm »
65 gives me a very low MC, most North American hardwoods dry to 7% at 60'C.

Offline Den Socling

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Re: Home made vac kiln
« Reply #105 on: March 19, 2017, 07:41:41 pm »
For those you thinking " I thought vacuum drying was low temperature", I'll explain. Most free water will evaporate under 115'F but removing the bound water needs more energy - higher heat. To get to 7%, you need 140'F with most species.

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Re: Home made vac kiln
« Reply #106 on: March 19, 2017, 09:50:27 pm »
Dan, I agree with you.
We have dry oak to a moisture content of 12 - 14 %. Quick sell. Winter operating humidity oak joinery product 5-6 %, the company does not give warranty on their product where moisture content 12 - 14 %. Dan, you're right to say, bound water requires more time and temperature than free. No one makes the oak thermal treatment. Why? Because humidity 12-14% for large ThermoWood. The steam from the wood will absorb the temperature . Quality ThermoWood is obtained from the humidity 6 %.
I recommend to dry oak to a moisture content of 6 %.
Sergey

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Re: Home made vac kiln
« Reply #107 on: March 19, 2017, 10:16:23 pm »
Sergey, we have built a couple kilns that do thermal modification. The reason I don't add it to our product line is because of the high cost of components. The high temperature heaters cost a fortune. Pumps and heat exchangers are expensive. I decided to leave it to companies who want this small market.

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Re: Home made vac kiln
« Reply #108 on: March 19, 2017, 10:56:40 pm »
Den. I saw Finland ThermoWood 20 m3 the price of 800 000 euros. Italy 40 m3 650 000 euros. Made of stainless steel 1.5 mm - 2 mm. Size large. I experimented a lot, made two technology in one machine, drying + thermal modification. We have a complex technique forest will not go, few literacy workers. I agree, the contact heating method of stainless steel, expensive coolant circulation pump, expensive, expensive measuring instruments. I've done black metal , separate alimenti stainless steel, used fireproof paint, non contact method of heating convective. Our price 5-10 times lower. It is important to note that vacuum drying + thermo sold together and not in separate chambers. To reduce price you can buy the tank metal 17 - 22 mm. It is eternal Luggage. Buy from us at the price charged , which is below the stainless steel. I took advantage of these hidden reserves and created a good price.

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Re: Home made vac kiln
« Reply #109 on: March 19, 2017, 11:07:03 pm »
Several options for the production of used tanks.














Offline Den Socling

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Re: Home made vac kiln
« Reply #110 on: March 19, 2017, 11:25:41 pm »
Yes, if your manufacturing cost are acceptable to the market, it makes perfect sense to use a vacuum kiln to dry and then thermally modify wood. Here in the US, it is too expensive.

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Re: Home made vac kiln
« Reply #111 on: March 19, 2017, 11:38:10 pm »
Den. I hope to visit Canada. There is my furnace with thermo. Long is the certification, I have not yet received. I really want to see You, but I was in the US you need a us visa.
Sergey

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Re: Home made vac kiln
« Reply #112 on: March 20, 2017, 02:39:17 pm »
Hi Sergey,
All I can suggest is that you email when you know that you are going to be in Canada. Maybe, if business allows, I'll visit for a meeting.
Den

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Re: Home made vac kiln
« Reply #113 on: March 20, 2017, 11:02:41 pm »
Dan, thank you very much!
Sergey

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Re: Home made vac kiln
« Reply #114 on: March 21, 2017, 10:34:30 am »
One thing Sergey, Gmail can never find you in my contact list since your address is in Russian. I can respond to your email but I have not found a way to initiate new mail.

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Re: Home made vac kiln
« Reply #115 on: March 21, 2017, 01:46:09 pm »
Den. I wrote you a letter on personal mail.

Offline Den Socling

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Re: Home made vac kiln
« Reply #116 on: March 21, 2017, 03:36:51 pm »
The gmail address bounced back but the other appears to have worked. You should find a note from me written in Russian!

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Re: Home made vac kiln
« Reply #117 on: March 21, 2017, 03:47:40 pm »
Bounced back again. I had to delete the gmail address from contacts and I think the latest went through. If you don't see a message in Russian, let me know and I'll start all over.

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Re: Home made vac kiln
« Reply #118 on: March 22, 2017, 12:10:22 am »
Den. Thank You for doing the connection between us. I will ask their children to do the correct translation. When you write to me, on the forum the translation is very good! When I'm writing, a bad translation :(.
Sergey