Need advice on using freight container for klin.

[alsayyed]

Hello everybody I am going to get 20 feet cargo container. I am thinking using this one for drying wood, but you know this container gets very hot especially in the summer not to mention that  our summer is very hot. Do I still need fan inside to circulate the air. Do I need to cut 1 x 1 meter in the ceiling or in the side to place glasse or clear plastic sheet for the sun to go through in order to get some heat. Has anybody used this type of cargo container is it ok. I need some advice. I appreciate your answer.

[dundee]

Al Sayyad, I  am looking forward in hearing from our FF members their comments !!--I know your country very well, it's hot-hot and no humidity so to speak.

If I were you, I would build a simple 3 sided shed, place the lumber on stickers and place 2 or 3 commercial fans to drag in the heat and create a air flow, you may have to spray water on the stack to slow things down I would think

Good luck

Richard
New Zealand

[alsayyed]

I already have one but I think it is small. I think I should go tomorrow and remove the wood becuase it is laying for almost 3 months in the klin. I should remove them and put them in the shade.

[Ianab]

Yes you will want fans to move air around in the kiln and some degree of venting to let the moisture escape. Do you have problems with wood drying too fast and cracking? I so then you need to reduce the venting, allow the humidity inside the kiln to increase and slow the drying. If the wood dries too slow and stains or moulds then you should increase the venting and bring more dry air in.

I dont know much about solar kilns in a climate like yours, but it's possible that a metal roof / sides may gather enough heat to dry the wood without a special collector. Maybe painting them black would help? The normal kiln designs are optimised for much cooler climates so different things may work for you. Insulation and double layer solar collectors are probably not needed etc.

Whatever you build I think it should have fans and some form of adjustable venting to allow air exchange from the kiln.

Cheers

Ian

[Den Socling]

Since hot air rises, I would consider modifying the container to create natural convection. Normally, temperature is low as possible and humidity is high so you need fans to move enough air to carry the water. If humidity is low (coming in) and temperature is high, you don't need much air movement. Perhaps Sergey's ideas would be applicable. https://forestryforum.com/board/index.php?topic=17127.0 maybe air inlets in the bottom center and an air plenum left in the center of the stack and vents in the roof on both sides. Then just vent enough to dry at an acceptable rate. If you see cracks, vent less. Temperature may be high enough to kill most mold.

But if you're drying hard maple, it won't be white.  :D

[scsmith42]

Greetings Al Sayyed.

I have a 45' hi cube shipping container kiln, with a Nyle 200 dehumidification unit and Wood-Mizer controller. In your geographic area, if you use a non-insulated container I think that you may have a problem with keeping your temperature low enough during the first phases of drying; because if you heat your load too hot too fast you will get a lot of checking in your lumber.

Here are some of my lessons learned:

1. Purchase an insulated container if at all possible. High cube (9.5' ceiling height) is the best way to go.

A 45' length will let you get two carts of 16' cants and one cart of 12' cants in the kiln, which works out to around 4500 bf.   However, unless you are drying softwoods that can safely withstand fast moisture removal, a more realistic load size is 1500 bd ft.  This will fit into a standard 20' instulated container - a better way to go than what I did with my 45' box.

2. If you can't get an insulated container, the following process is very effective: Glue 2" foamboard (R6.5) to the inside top, sides and ends of the container.

Over this, glue FBBWP (foil, bubble, bubble, white poly) Tekfoil available from FarmTek (www.farmtek.com). It's about 3/8" thick, and has an R value of 10.

This insulation combination is unbelievably effective at retaining heat inside the kiln, and moisture will not easily condense on the white poly. On a seventy degree day, with an inside kiln temperature of 120 degrees, the steel outer shell of my container is about 72 degrees.

3. Build a track system inside the kiln, and even more importantly, extend the tracks outside the kiln. You will need to have about a 4' removable gap between the kiln and the outside tracks to allow the doors to close. The Nyle manual provides an example of an effective track system. Don't skimp on your kiln carts or cart wheels.

Inside track is important because the weight of the lumber can punch the cart wheels right through the wood floor of the container. Track outside the kiln is critical in order to use a forklift or tractor loader to load the kiln carts.

4. Build a relief in the side of the container for the dehumidification unit to sit in. It provides for more consistent air flow through the kiln and you reduce the chance of damaging your dehumidifier during loading or load inspections.

5. Install one fan for every 8 feet of container length. I have 5 in my 45' container. Hang the fans on rubber mounts (Grainger's has them), otherwise the steel container will reverberate and you'll hear it humming 600' away.

6. If you live in a rural area that is subject to power outages or surges (such as when a tree strikes a power line), be sure to install a surge arrestor on your load center. The kiln controllers can be susceptible to voltage surges. You can get surge arrestors at an electrical supply center.

7. If you purchase a Nyle unit, consider ordering the extended length cable from the controller to the dehumidifier. The standard 6' length is a little short.

8. Clean and paint all exposed metal surfaces inside the container, as moisture will condense and the metal will rust quickly. This is especially important on the insides of the doors and bottom of the door frame.

The folks at Nyle are really great, and their products are top quality and reasonably priced.

I have about 11k invested in my container kiln, excluding labor. Breakdown is as follows:

Container, delivered: 1,500.00
Nyle (Wood-Mizer) 200 series kiln: 4,745.00
Three extra fans (Nyle): 725.00
Moisture meter: 410.00
Steel for kiln carts and tracks: 1,000.00
Kiln cart wheels (Nyle): 420.00
Insulation (1" foam) 45 sheets @ 13.00 ea: 585.00
Insulation (Tekfoil FBBWP) 1,500 sq. ft.: 600.00
Misc electrical (load ctr, boxes, wiring): 350.00
Plywood and hinges for baffles: 350.00
Misc hardware: 100.00
Metal and wood for side kiln chamber: 200.00

Total, excluding labor: 10,985.00

From a labor perspective, it took the following: Two men about 40 hours to glue in the insulation, with furring strips for extra support, and to build the side kiln chamber. It took two men about 40 hours to install the fans (including electrical) and fabricate the plywood baffles. Finally, it took two men about 50 hours to fabricate three kiln carts (two 16' carts, and one 12' cart), and the track system inside and outside the kiln.

I have some 20' insulated shipping containers that were used to ship frozen foods across the oceans.  The are very effective at keeping the hot temperature outside, and if you can locate some of these, I can't think of a better way to go.

Good luck.

Scott

[Den Socling]

With all due respect to Scott, you don't need a DH unit. Nor insulation. he's in a different climate.

[oakiemac]

I'd think you would need insulation no matter what enviroment you live in. Once that lumber is up to temp and it is nice and steamy, if you don't have insulation at night it will condense and drip back onto your wood. :( Also the chamber will rust out faster with no insulation due to the vapor condensing.

[Den Socling]

Right now, Qatar is in the 90'F range during the day and around 75'F at night. The wood at night would be too warm for any condensing on it. But you would see condensation on the walls which might include acetic acid. Okiemac is right about the roof needing insulation or it would drip.