Log drying kiln idea

[arboriculturist]

You need to replicate on a smaller scale exactly what the commercial manufacturers produce only on a smaller scale.

However I would not consider investing in most of those on the market in the UK as they are inefficient and costly to run due to fundamental design flaws. If you are on the feed in tariff of course this doesn't matter so much.

[Woodworks]

I have toyed with making a kiln along the lines suggested but when you look at what a commercial dehumidifier can remove it does not look so good. Say you have 10 cube of logs in the kiln thats around 5 tonnes of wood. previous tests have show you lose approximately 150 litres of water from a cube in the process of drying. Times that by your 10 cube you have 1500litres to remove. A quick search shows a commercial dehumidifier at 35C and 100% RH removing 38 litres per 24 hours and thats at it's optimum. So pretty much 40 days with the dehumidifier working at it's paper spec best which I am sure would not be achieved in the real world.

 

This was the dehumidifier spec https://www.energybulbs.co.uk/broughton+cr40+d+v+heavy+duty+industrial+dehumidifier/1691097694?gclid=Cj0KCQjwl9zdBRDgARIsAL5Nyn2Dpj0fgQiiCtWjOU8PSO5bbl0yqKZz23Us9Rs0Hg9MUscq3Vi82V0aAvaXEALw_wcB

Edited October 5, 2018 by Woodworks

[sandspider]

My dehumidifier (a decent brand, but not commercial) claims to remove 10 litres of water a day. In practice it will do 1 litre, maybe a little more. This is at about 80% humidity, 20C ish. Manufacturer's figures are wildly optimistic!

[arboriculturist]

A dehumidifier is a 100% waste of time. It will only remove what is in the atmosphere surrounding the timber and in any container it will be months and months before the wood tissues give up their MC. ?

[SbTVF]

You need to be getting temperatures well over 50 degrees to even come close to being effective. Ours runs at 65-75 for a week with enough air flow to completely change the air every 30 seconds and it still takes a week to dry 16 cube from 35% moisture to 15%.

You need high temperatures to increase the water carrying capacity of the air and then lots of air flow.

Ideally a heat recovery system is used on the wet air vent to remove the water from the air and send hot dry air back to the air inlet.

[jrgatelogs]

Hi all. Sorry I’m late on this topic. We have a couple of Glen farrow kilns. A flaw I’ve found is the vents at the bottom by the doors, I’d imagine they would be better at the top to release the moisture once it’s circulating in the air, otherwise it will just blow about in the top of the container and as soon as the kilns cool overnight the ceiling is covered with moisture. Even running it 24 hours I can’t see how the moisture can escape. I was wondering about a industrial dehumidifier on a timer to just come on for a couple hours 3/4 times a day to pull out the moisture. At the hottest point we get to 45/50 degrees this time of year, up to 60 in summer. I’m no expert but I imagine if there’s enough heat to get to the centre of the logs, and some way to get the damp out it should dry. 
i know I’m late to this, so if you have built something could post some info and photos please? 

[openspaceman]

2 hours ago, jrgatelogs said:

Hi all. Sorry I’m late on this topic. We have a couple of Glen farrow kilns. A flaw I’ve found is the vents at the bottom by the doors, I’d imagine they would be better at the top to release the moisture once it’s circulating in the air, otherwise it will just blow about in the top of the container and as soon as the kilns cool overnight the ceiling is covered with moisture. Even running it 24 hours I can’t see how the moisture can escape. I was wondering about a industrial dehumidifier on a timer to just come on for a couple hours 3/4 times a day to pull out the moisture. At the hottest point we get to 45/50 degrees this time of year, up to 60 in summer. I’m no expert but I imagine if there’s enough heat to get to the centre of the logs, and some way to get the damp out it should dry. 
i know I’m late to this, so if you have built something could post some info and photos please? 

I'm not familiar with these kilns but is there not a fan blowing fresh air into the kiln?

[WINTERBOURNE]

We have a boiler specifically for the kiln drying industry.

We have the Angus Orligno 600 hot air blower which is the ideal boiler for hot air process and space heating.

Emberair have done a number of installations where they are heating 20 Foot or 40 Foot containers.

Please see http://www.ecoangus.co.uk/angus_orligno_600_boiler.html

We work exclusively with Emberair as far as the supply and installation of this particular product range with contact details as follows

E-Mail [email protected]

If you would contact Simon as far as further details with your kiln drying requirements he should be able to assist as they have installed a number of boilers for this very application.

You can see one of these boilers being used for kiln drying by a customer in Kent on https://www.youtube.com/channel/UCiJAdtYNuPqaCIn4KPJBLGg/featured

Also Emberair have a Facebook web site which shows a number of kiln drying installations https://www.facebook.com/EmberAir

Edited March 11, 2022 by WINTERBOURNE

[jrgatelogs]

8 hours ago, openspaceman said:

I'm not familiar with these kilns but is there not a fan blowing fresh air into the kiln?

Yes. There’s 4 fans behind the radiator blowing fresh air in but the vents are at the bottom of the kiln which seems odd as surely the moisture would be better vented out at the top? 🤔

[openspaceman]

1 hour ago, jrgatelogs said:

Yes. There’s 4 fans behind the radiator blowing fresh air in but the vents are at the bottom of the kiln which seems odd as surely the moisture would be better vented out at the top? 🤔

In that case I wouldn't worry as the pressure from the fans will far outweigh any difference in buoyancy of moist air and it may be that heat is better conserved because as the warm air picks up moisture it cools and cooler air plus water vapour will fall even given water vapour is lighter than air normally.