What's the Best Way to Dry Wood Chips Mechanically?

Freeze drying is an innovative concept.

You might also look into a vacuum process since time seems critical.

Were time not a factor you could obviously just lay them in the sun....

Edignan, I think you are right on the vacuum process...to assist a primary process.

We've only heard of the sun here! How to lay chips on top of clouds?

Hi OT,

If these chips are fir/pine, one of the issues with mechanical processing would be how much pitch will there be to gum up the works.

Mike

Mikerho, we haven't had that problem as the constant abrasion and wetness keep things clean.

first thing that comes to mind is a dehumidifier room where the chips can pass through in a layer of vibrating conveyors snaking though the room at several levels. as they fall and move throughout the room, moisture should be removed by the process by the dehumidifying equipment.

IMHO, freeze drying is an energy-consuming dragon, and would not be feasible for your product (it can make the final cost sky-rocket).

Thank you! I'll look into the dehumidifying equipment.

Water in wood demands a lot of energy to remove quickly. It might evaporate in time as it come to equlibrium with the local vapor pressure (which must be less than that the wood will produce at 30% water. with that tonnage you will need to input some energy to replace the latent heat of evaporation of 25 tons per hour from 60% to 30% water.

A fast calculation shows that 50,000 wet pounds of wood hold at 60% 30,000 pounds of water, and thus 20,000 pounds of dry wood. For the final wood to be 30% water it will be about 29,000 pounds wet, so 21,000 pounds per hour of water need to be boiled off.

Now it can be sun dried, but to add that 50,000 pounds per hour to a pile so you withdraw 29,000 pounds per hour would need a huge pile with 30 days or so wood stacked in it and roofed over = huge operation with just sun heat.

It might be efficient to add a microwave heater through which the wood will pass and you add the heat and blow air through. This will need to be a powerful station to boil off 21,000 pounds of water per hour. gas heat might be less efficient, as most heat = wasted. Microwave heats the water, but is only 50% efficient, but it goes where needed. A study needs to be done..

Aurizon, how would one calculate the energy consumption of a microwave running at 110% of these conditions?

Langyaw, thanks for sharing your ideas! What industry uses dehumidifiers of this magnitude? Isn't it the same concept as compressed air dryers that cool the air to below the dewpoint to drop out water?

try contacting any of these American companies.

http://electronic-components.globalspec.com/SpecSearch/Suppliers/Electrical_Electronic_Components/Fans_Electronic_Cooling/Industrial_Dehumidifiers?SrchItem=1&frmqry=dehumidifier&kqid=201200786

Try Briquetting press manufacturer.The technique is well established considering the fuel oil prices(few days back).

Hi Oregon Tinker,

One way or another, energy must be spent to do it, but gas is out of question as its burning also produces water vapour and this would lessen natural evaporation of water from chips.

If there is enough sunlight available, I could design You system that would work 24/7 and You can draw electricity from it also. It would be similar to my Solar Power Stations, so I could let You use it in exchange for patenting it in Your country.

To boost evaporation, whole system could be turned into big microwave owen, but then Your conveyor line cannot be made out of metals that are incompatible with microwave emissions. Since You would have cheap electricity, spending it would not be problem.

In addition dehumidifying systems should also be used to remove already evaporated water from process, but it could be simple distillation system if outside is very cold anyhow. So You can produce distilled water as well in great quantity, pack it and sell, it is rather expensive in my country :-))

I have invented system for production of water from air by condensation that spend little electricity, and here it could be used as dehumidifier. It would be cheaper because there would be no need for filtering condensate, and simple piping system can drain all dehumidifiers into common reservoir otherwhere. I believe I can make completely passive system also, but to test this theory I need some good CFD software like SC TETRA, but it is rented for 15 000 $ per year, which I cannot afford at moment. If You can provide that software for me, I shall give You free licence to install and use such systems in this plant, with just small % of profit from sold distilled water :-))

Electricity produced by Solar system can supply power for conveyor line as well.

But if You are willing to spend electricity, then the system for compressing chips into a sticks trough pipe using screw compress should be fastest and could be made into continuous process, but You have to see if this is economical or not.

Still simpler system would use waste heat from furnace chimney to heat chips by blowing trough them from downside trough blowers, while conveyor line can go trough tunnel, and tunnel has to have many chimneys instead of one only. Bad side is that conveyor baskets should be sieve like and have similar cover so chips would not get blown away. That baskets should also shake or turn so chips would be mixed and turned over (in any case). Good thing is that tunnel can have metal walls that form great circle, and waste heat could be used to warm big greenhouse inside of that circle for raising vegetables even in cold weather. Good is also that part of soot from smoke would be catched on chips and be carried back to furnace, saving You part of smoke rinsing cost......

I hope if You implement any of this ideas that You would remember me and send some cash to poor inventor from poor country........

Is this new project? If not, how did You do it till now?

Regards from Zagreb, the capitol of Croatia, Europe!

Henrik 14, you're very bright! All we have here is water, trees and cold wet wind. We can almost generate electricity with a waterwheel standing in a field catching rain.

I don't know if this has been done before. It is new to me. Most chip powered plants wouldn't need to pre dry because the de-gassify the chips then burn the gas where we are burning the chips in a traditional fashion.

I like the greenhouse idea, we would need to put in a sunlight piping system from above the clouds though.

Not enough sunshine, then? Forget it! Read my previous post!

The only way it can be efficiently done is a rotary drum dryer this is an old technology that injects heat down the tube while the chips pass through by means of the interior auger type blades (like cement mixer).It takes a lot of energy to accomplish what you need to do , as ealrier calculated .There is no simple way out.

If you find a better way best of luck.I have been involved in the chip business for about 20 years many company's want dry chips but do not want to pay for that process.Eventually somewhere along the supply chain someone is forced to install a dryer

If you have the material burn sawdust to fire the dryer all very complicated unless you find an existing facility at auction for short money.If you find a way let me know.

Traditional, can I assume then that chip board mills have chip dryers of a large scale? Do they use super heater steam to dry them? It is my belief that paper mills buy chips by the bone-dry unit (and sample every load) so that they don't pay for water but that the only drawback to 'wet' chips is the increased risk of spontanious combustion in storage piles. I can't imagine that they would dry the chips.

Oregon it is a pleasure to have someone show the respect to return all comments

Most buyers take in green chips but there has recently been inquirys for dry material in my area for pellet production they have further stipulated low bark content I have stayed away and stay with the mulch and biomass markets .I suppose if your looking into your own uses it may be a different story I think high compression will drive some mosture out but there is allways the cost verse gain.I would be curious what is your application?

Traditional, we need electricity for a small very remote community, they are currently running diesel generators. There is a far more than sustainable supply of whole log chips which we would like to use to fire a standard boiler but the chips are very wet due to being grown in a rainforest. The group has stated that we can't use the boiler exhaust, any form of petroleum fuel and any more electricity than consumed by conveyors. I think we will use more electricity than that.

the boiler will vent exhaust gasses that could be used to dry wood in a counter current dryer to achieve their end. Why does their doctrine say you cannot use the wasted heat of combustion to dry the wood??

In any event you can use the heat of the fire to dry the wood with the correct design of combustion chamber

Aurizon, I am still trying to change their mind on the exhaust gasses. Most sawmills, plywood plants and the like here in the Northwest have a problem in the winter season with high moisture in the bark we burn in our boilers. Many have used exhaust gasses to pre-dry the fuel. Most larger (600 horsepower and larger) wood fired boilers use force draft fans to feed the fire and induced draft fans on the exhaust side. This means we can use the exhaust in almost any configuration because we don't need natural draft.

I sense a combination of solutions on the horizon!

I see....

Because You have wet wood chips, You use forced draft to rise temperature of fire, and they perhaps think if chips are drier than usual that hot exhaust gases can set fire in chips before they reach boiler? But in such case You need just ability to transport chips at various speed, faster when they are drier than usual, and also system to regulate quantity deposited on conveyor to be smaller......

Why dont You simply tell us why they are opposed to using exhaust gases to dry chips?

If chips would be dry, then You would not need forced draft, do You?

Anyhow, for good draft You need just tall chimney, or at least long enough if it is spiral like I proposed.......

Main thing is that it could be modeled very precisely using CFD software I mentioned, and since there would be no need for forced draft, You would need just energy to run conveyor, and conveyor would be assisted by gravity force partly if You use my idea.

Alternatively, if ventilators are used on top and system can be enclosed so slight vacuum can be created, chips would dry even faster, but I believe this would not be necessary.

Anyhow, You burn those chips partly to get rid of them, dont You? How about turning those chips into methane first, and then into bioplastic, composite glues and fertilizers instead of just burning them? But this would ask for big flat area, and weather is cold like You wrote before, so I would have to ask inventors of this technology whether it would work or not. Perhaps it could be done part burning and part biodigestion, and shortest path would be to burn Methane or Biogas produced, but if it is turned into liquid state it can be fuel for cars or used for cooking, right?

Electricity You can get from the river, if barges are traveling on it.......

Now, I got another idea, with also spiral conveyor, but acting as feeder to fireplace and going down trough chimney AND trough FIRE itself to pre dry chips by heating them almost to point of smouldering, and focusing ventilators positioned in circle to blow trough fire and into chips that are coming from above. That way chips already dry and because of this light enough to fly would be lifted off conveyor and fall into center of fire..... Hot conveyor plates or baskets would preheat chips from start also, but they would not burn since they are too wet anyhow....

Only other solution would be to have extremely long flat spiral conveyor protected by the roof, by which chips would travel even few days slowly on surrounding air to lose their water in desired quantity, perhaps with chimney pipe going underneath to provide some heating and therefore drying the air..........

That would take more space and more materials to build, and first idea gives long chimney that would make forced draft unnecessary, so less electricity would be spent and there would be no ventilators to maintain, and nothing that could break. If there is enough wind, I have system that can replace forced draft made by ventilators also.

If system is carefully modeled, there would be no accidents possible and thing would be optimized for minimum expenditure of energy and maximum production of electricity.

Exhaust gases cause greatest waste of thermal energy that is produced, so to forbid its use is really shortsighted.

There is another option that would capture part of heat that exhaust gases carry, and this is to make chimney spiral go around boiler and there could be radiator ribs on chimney spiral from outside that would produce updraft hot air for drying chips as they come down in spiral, thus persevering part of heat naturally lost from boiler and heat that would be lost from outside of chimney can be used productively also.

Such system would not use heat as effectively so it would have to be much taller, but there is no danger of fire starting in chips before they reach fireplace...... But then, because conveyor and chimney are not tied one to another, there could be three chimney spirals going up on sharper angle, that could be united into one chimney pipe on top, and smoke would tend to swirl while going out, which would strenghten normal >>Chimney Effect<< and make artificiall forced draft unnecesary.

Now, You chose what You like the best :-))

Marijan Pollak, IT SA/SE 1st. Class, Instructor & Team Leader (retired)

Oregon I have been interested in the same goal of power production I looked at the wood gasifier it is an old technology( common in ww2 ) that is getting renewed attention .

I am currently building one to run a generator . Plans are available on the internet .

But the same problem it calls for dry material . If your requirements are not huge I have thought to bag chips in burlap bags I have experimented and it does work . It returns to scale how big a generator=tons/yds chips.

The ideas of drying trays and recycling heat are good ideas it comes down to the amount of chips you really need .

I would be curios about the reality of exhaust emissions remember any fuel with have emissions so burning wood is at least carbon neutral therefore the least destructive.

I am sorry that English is not my native language, so that's why I cannot understand You.......

Any burning produces CO2, and since cellulose of wood is in group of CarboHydrates burning produce CO2 and water mostly. Therefore it is not >>Carbon Neutral<<...

Our coleague has stated his requirement and it IS HUGE, that is the main problem. Using burlap bags cost money and additionall work, and still You got to dry chips somehow, which is more complicated by bag, as inside of bag is hard to be influenced by any process of drying chips. Also, if You want to spend less, You would have to unload bags after drying of chips are finished, as to burn chips together with bag is not economicall..... So, IMHO, just leaving chips in thin layers on extraordinary long slow conveyor on open air (but under the roof to protect it from rain and snow) would dry them better, but to supply 2.5 tons per hour that would have to be wide as well, so whole thing would cost fortune. Therefore it is most economicall to use waste heat from chimney that would be lost otherwise, and forced dry chips by heating them..... There is way to turn wood to methane using bacteria, but chips would better be grinded to dust for this, and this require energy expenditure also.......

Anyhow, concern here is not about CO2 production, but about burning wood chips that are too much wet to burn. Even production of electricity is not most important here, as they have to dispose great quantity of industriall waste in first place, and automatic feeding of furnace would spend energy also......

I could just wish that they would produce something usefull and sellable instead of just burning it, but in such cold weather like is described even use of bacteria that would turn celulosis into methane would be impracticall. Producing Biogas can lessen use of gas for driving cars, and from it we can make Bioplastic, composite glues and fertilizers also. But at least sawdust could be used for this purpose, and surely there should be enough of it also. It would be best if there is some process to turn softwood into high quality hardwood plates, but unfortunately I know not if somebody invented such technology......

It would take genetic engineering and lot of imagination to produce plant that would eat chemicaly decomposed soft celulosis and >>grow<< hardwood plates with hardness of plum >stones<< or seed of dates palm, or some similar very hard wooden materiall. Perhaps one day we would be able to do such things when we would be able to understand genetic programs and how to make new one that would grow something usefull to us, maybe whole boats, chairs, tables, even whole houses with all pipes ready for use inside :-))

Sorry for digresion........

people might buy them for heating and deal with the drying issues themselves. Bagging in burlap and stacking them is not good as the burlap would rot.

a scaled up version of this would work,. It uses wet chips.

http://www.daviddarling.info/encyclopedia/G/AE_green_wood_chip_furnace.html

another

http://www.biomasscenter.org/pdfs/Wood-Chip-Heating-Guide.pdf

http://www.biomasscenter.org/

and this search might help

http://www.google.ca/search?hl=en&q=%22wood+chip+furnace%22+%2Bgreen&btnG=Search&meta=

Thank you aurizon, you are more than generous. I have written the sites down and will look into them.

Traditional, I was told to design for 20-25 tons per hour. That is a lot of chips. I ran a chip plant that produced 850 tons per hour green basis so I know what the volume looks like and how to handle the material.

I don't forsee any emission problems from regulating agencies, worse case we would use a multiclone and or scrubber.

What would be the average difference in overall efficiency in average conditions when comparing a wood fired superheated boiler (figuring 30% mositure content) running a turbine generator, to a degassifier using the same raw materials and a gas burning internal combustion engine and generator? What are the pros and cons?

Henrik14, my part of this projects is to dry the chips, the boiler is provided by someone else, and the chip supply is yet another's responsibility. I believe in whole system engineering for many reasons.

You are right about the short sighted decision on not using exhaust gasses.

You have many good ideas so far. You may figure this out before I do.

Burning wood is considered carbon neutral when forests are sustainably managed and transforming the carbon back to oxygen...or something like that.

The chips can be heated to beyond their flash point if in the absence of oxygen, right?

If you heat the wood chips to a high temperature....this is called destructive distillation of wood and produces a range of chemicals, methanol,and many others and tar.

http://www.google.ca/search?hl=en&q=%22destructive+distillation+of+wood%22&btnG=Google+Search&meta=

I forgot that! Also releases the VOC 'blue smoke'.

That chips can be heated to beyond their flash point if in the absence of oxygen can happen in case I described where metal baskets would spiral down trough the chimney down into the fire, as smoke dont contain much oxygen after hot products of burning rise up from the fire, but temperature itself should be enough for water in chips to start boiling and fast reduce water content. But problem could be forced draft that could blow chips trough chimney, therefore baskets should be closed until basket come to unloading place to throw chips into fire. Actually it may not be bad even if chips would be burning in baskets, as then ash can be automatically transported out of fireplace.....

You still did not explain reasons why they want to avoid use of waste heat?

If chimney is made out of silicate bricks then microwaves can also be used in chimney and fireplace instead of forced draft and this would take down number of moving parts and lessen electricity consumption, I would say....... Strong enough microwaves can fast turn chips into wood coal, and uniformly at that. Combined effect of waste heat from fireplace and microwaves would bring energy consumption to minimum.

I remember how on first try I turned bread slices into coal that even started burning :-)) so it was for good cause as now I can help You with that wet chips.

Microwaves are really the best (if I understood properly how they work, and it is by targeting water molecules specifically) just there should be some protection from stray microwaves on chimney exit (perhaps with strong magnetic field) so birds flying over would not be incinerated also, and baskets should be of special materials too.

I think in the end all depends on budget.

But it cannot be done like You described, that each part of system is treated separately as nobody can make system out of incompatible parts. At worst, it would not function at all, and at best it would be inefficient energy converter as there would be no synergy between parts and each place would have its energy leaks........

More expensive to build and to maintain and repair, which is also cost.........

Whose idea it is anyway? Somebody has to have clear vision how things would function as whole, as each part influence other parts.....

Starting from feeding chips to fireplace in such quantity, assuming they came there dry enough to burn, to evacuation of ashes that also must be continuous process, it determines type of fireplace to be used. Since fireplace has to effectively heat boiler, then boiler should fit fireplace, and most effective boiler is one with biggest surface exposed to fire, therefore fire and smoke should pass trough it, if possible on its way to chimney.... Therefore it is best to make several chimney pipes to pass trough boiler, or one central hole. Since there should be tunnel for conveyor feeding fireplace, why not use chimney for double purpose, and in process dry chips so they would burn easy? If in addition chips use baskets for moving fireplace, ashes could be evacuated at once after burning chips, so this problem is also solved.........

As I wrote before, to have enough draft You need just chimney tall enough, and even additional silicate bricks are cheaper than big ventilators, specially such that would be exposed to IR radiation.......

Ashes are problem by themselves, so better be prepared to collect them and pack and sell as fertilizer, but You cannot think of such >>details<< when there would be big pile of ash acumulated.....

They cannot just be dumped in river, mind You :-((

Whatever You do or construct, treat it as system with its own inputs and outputs, and think of bigger system (like environment) whose part it would become......

To build effective system, think of synergy and emergent characteristics of processes going inside...... Do You know that nowadays they dont dig coal out of ground but use coal eating bacteria that produce methane, and they collect this and send trough pipes..... I am sure same bacteria can eat Your chips, but You would need big reservoir for that purpose as process is not so fast to be able to digest easyly tones per hour, and then burning methane would not be only option. Since there is river, for making electricity You dont need to burn Methane produced, and at least fertilizers can be sysnteshized from it, which would be more valuable to sell, dont You think?

Cheaper fertilizer would make food production cheaper and more aboundant, so people would be able to buy more with same amount of money, right? There could be also composite glues and bioplastic produced, and that in form of plates could help isolate Your houses from cold and from heat also, so some energy would be saved, and that means less expenses and less consumption of fuels, which means less CO2 produced and at same time more CO2 removed from atmosphere, which then could bring Carbon Credits...........

Would that not be better that just staying >>Carbon Neutral<<? If bacteria produced in process could be fod for some microorganisms in ecosystem, then You could have end result of more fishes in that river, which could then be exploited commercialy or just for sport of fishing, or as adition to food industry.........

I have some coleagues that have developed such technology that would turn agriculturall waste into Biogas, just I dont know if it is applicable in cold climate.....

Well, in the end it is just another engineering problem, as all that has to be done is to use materials that are isolators, like that same bioplastic plates glued together with that same composite glues that would be end product of such instalation, so all You need is big flat space, preferably where that river would not flood it.........

I would really like to know what people who originated this project would think of another use for that wood chips, other than making lot of smoke and ashes?

Regards from Zagreb, the capitol of Croatia, Europe!

Marijan Pollak,

IT Systems Analyst and Systems Engineer 1st. Class,

Instructor and Team Leader

(retired)

Henrik14, I will explain why we can't use exhaust heat as soon as I know the answer. Ash cleaning is done automatically and the ash is then used as a soil suppliment. If the chips are to be dried and even partially burned by exhaust, they will need to be collected and or deposited into the fire pile outside of the wind stream. Otherwise there may be an excessive amount of burning material carried from the fire box up into the combustion chamber which causes an overload on the flyash and cinder collection system, glass like deposits in the bottom part of the combustion chamber and several other problems.

I agree that the whole system should be designed by one team and hope it comes to that soon.

I've not yet ruled out the use of microwaves. It may be found best to spend a great deal of electrical energy to dry the fuel rather than not burn it at all.

Sorry to see that You did not understand what I wrote :-((

Chips would be dried on their way to fireplace, so no storing them in interim is necessary, because they would be burned after being heated up to lose part of moisture.

With proper construction of boiler, which should form bell or conical shape over fireplace, it would not matter even if chips start to burn before they reach fireplace, as they would just add to temperature that heat boiler from the fireplace, and since there is little oxygen left in chimney, they could turn to wood coal at best, which would also burn, but by proper calculations it could be fixed so that just enough water is lost from chips so they can burn normally in the fireplace.......

But if there would be interest to better use that wood chips using biotechnology like I described, let me know and I shall consult with technology creators if it is applicable in this case........

Otherwise, I am sure that using microwaves would be most economical and need least repairs....

I am very much interested to know reason why using waste heat is forbidden, even if I can imagine that some may be afraid of causing forest fire, but this is also less likely since temperature of exhaust would be lowered and more water vapour would be present in it, and if there is no forced draft necessary, that danger would also be less.

Anyhow, I am repeating myself, and for all my posts on this thread I did not get even one GA :-(( so I would stop posting..........

I happened to work in paper and printing industry long ago, and they dont mind water as they cook wood chips anyhow and grind it wet to produce raw cellulose. They know what percentage of water is, so they pay that much less per m3 of chips, if somebody would sell chips, that is. Usually they use classic logs for firewood that should be debarked first, and then special machines turn that into chips that goes to cooking with some acid, therefore they just need less water to add......

What would I like to know is who is delivering those chips and why they dont use this wood for something more useful?

If it is just to produce electricity, You have river there as You mentioned, so that must have to be branches and pine needles You are using that are cut to chips?

Still, would it not be better product to make firewood or wood pellets for fireplaces to burn? Well, I guess it is mostly bark and pine needles anyhow.....

Henrik14, we have hundreds of sawmills around here and trees are growing faster than lumber is selling which has dropped and stagnated the value of timber. Paper mills are also very slow now, they get all of the chips they need from sawmill waste. The supply of firewood on the market is slightly higher than demand due to unemployed mill workers having a need for money. Wood pellets are in high demand and the factories are starting to have problems getting sawdust and shavings with all of the mill curtailments. We have access to an abundant supply of wood chips right at the boiler and we are determined to burn them.

patented? Just give us the patent number and we will look it up

Possible Solution:

Cut down the wood into pieces. Make the pieces small enough that the moisture will be released in a short amount of time through evaporation. Location should be in a place with: 1. a high altitude (i.e. vacuum), and/or 2. a wide open sunny/ dry location (i.e. dehumidifier), or provide/ find a location with opportunity for quick evaporation.

As for fire dynamics. I don't know how the size affects the amount of heat or the intensity of the heat generated from the wood you are using. Why not saw dust over wood chips?

The best would be if you can use your environment as a source of energy.

Look into vegetable dehydration.

Someone has to know something about using 'screw compressor' technology! They are used to compress air, move concrete, uniformly feed and compress recycled plastic and wood fiber, as a shear for recycling bulk materials...why not for super compressing like wood pellets, fire-logs, charcoal briquettes and driving the moisture out of wood chips?

It is an honor to have this dialog with this group!

I have seen that somebody in Croatia has made machine that make round sticks out of compressed wood chips, but that was for commercial sale for firewood at home. You would need awful lot of such machines to process quantity in question on continuous basis, so perhaps You would end spending most of energy You are supposed to produce......

Only way to get it cheap is to use waste heat from chimney of boiler You are stocking with this chips, so in the end You may end feeding fireplace trough chimney, while chimney would be long tunnel trough which wet chips would travel and gradually dry. It may be long screw type transporter that would mix chips while pushing them forward, and there should be blowers underneath blowing hot air and smoke up, to be let out trough small chimney overhead. That way process would sustain itself for free and only cost would be to build whole system. Energy that would have to be spent would be almost same one that You would be spending anyway for conveyor that should feed fireplace, but to remove half of water from chips there would be need for for chips to travel long way. Perhaps instead of straight tunnel You should build 36 angled double pipe inside of which there would be cascade of screw transporters going around from highest point to fireplace, and chimney should spiral underneath with blowers on it like I described before. Blowers should be smallest and more numerous closest to fire and biggest near end of spiral chimney. Of course You have to calculate diameter and height necessary for chips to pass trough heat long enough to dry. Spiral conveyors could be connected to turning mechanism situated inside of center of this structure, or they can pass rotation to one another using cardan joints. Blowers should blow directly inside pipe containing screw conveyor from below, so hot air would be directed at chips , and most of holes in pipes should be on upper side. To spend less energy, each pipe with screw conveyor should be down slanted in direction of transport, so gravity would assist, but that can make path much shorter, unless structure is much higher. Alternatively, there could be 360 shorter segments for one turn of spiral, just You need that much more cardan joints. Slant of downward path should be calculated so that next spiral turn come directly beneath chimney pipe spiral. Since blowers would blow on screw segments that would push wood chips, part of heat would accumulate there, providing additional heating of chips as they are mixed and pushed downward, so it must be done carefully lest chips start to burn from contact..........

This is only way to get drying almost for free, and regardless of weather conditions outside. If You provide me with CFD SC TETRA software, I could make simulation of such installation for You, or it could be my fee after You dont need it any more, or You can rent one copy for me....

Now, I gave You solution that could save You big pile of money, so I hope You at least let me patent idea so I could sell it to someone else, in addition to that CFD software........

That is how I would do it, but I am no expert in this field, I am just inventor and Systems Engineer :-))

Screw compressor technology is same as that in meat grinder, where turns grow progressively closer and smaller in diameter. But instead of ending in open, at end of screw there is system of three segmented massive tool that is pushed by hydraulic pressure together. When hole at meeting point of those blocks get filled, blocks pull apart and pellet fall out. There could be fine holes surrounding screwing part so water can leak out, and also in those blocks, but they are very small so chips would not be pressed into them...... System could be mechanic also instead of hydraulic, but still there should be hydraulic pusher if just one hole is used, or system could be revolver like, with one hole being filled up while other is emptied. I would even think to use push produced by screw compressor to push finished pellet out of hole at same time using levers....

But process is relatively slow, require energy to be spent for mechanic work, and for such quantity You would need many of such devices to work in parallel, so forget it!

I personally like the idea of using the exhaust to dry the fuel. Having worked with wet wood before, it might be tough to get enough heat to boil water... much less get up a head of steam.

You might ask the OSU Extension Service over in Corn Valley (Corvallis).

www.extension.oregonstate.edu They might have some ideas.

Bill <-- Oregon Native

Any drying scheme that involves heat - microwaves, stack gasses - is going to require adding the heat of vaporization for water, which is considerable.

Look into centrifuging. You are reducing the moisture, not eliminating it, so the centrifuge may do the job for very little energy input.

LG Dave, I had a similar thought this morning when I saw our centrifugal 'juicer'and thought it wouldn't work...but you may be right in that we're only reducing the water rather than eliminating it.

Thanks!

Considering quantity and that this has to be continuous process, I think You are on wrong trail. Energy expenditure for scaled up centrifuge and its construction cost would be too great.

Screw compression could be made into continuous process and should eliminate enough water, but still You must spend lot of energy out of that which You intend to produce in first place.........

Please read my previous post, as this would be best if it would be considered how to best use material at hand instead of just burning it.......

Oregon,

A household clothes washer removes most of the moisture in the clothes with a spin cycle - it takes them from soaking wet to damp with very little energy. Then the clothes dryer uses a lot of energy to remove the small amount of remaining moisture. Maybe your process will be on the inexpensive part of the drying curve.

LG_DAVE

Wood chip drying !!!! I know you have requestd not using gas or electric!! Is this because the fuel is not available or you are just seeking alternaive routes!!

Have you considered an alternative drying system? CDS offer a system named RO2. Its a reduced oxygn drying system. However there is energy required... but at much reduced level than cinventional drying!!!

If you are interested please contact me at andy.hall@cds-group.co.uk

Best Regards

Andy Hall

I've started a new thread looking for insight into a mechanical process. I am getting closer to having permision to use exhaust heat.

I was asked to design a smaller prototype which will process 2 tons per hour, and encouraged to find a mechanical solution.

Thank you all for your continued support!

Oregon Tinker !!!!!!

I have some good news for you while looking through e bay in equipment section under (other ) heading I saw exactly what you need as I described before( a drum dryer ) It was called an "industrial peanut roaster" item#190296411464 it is -a drum dryer- located in California 36 feet log 7 foot diameter exactly the unit needed for your application they were asking 95k but I bet it could be had for 10k as there were no bids .I bet it had an easy life drying peanuts .I am sure the earier link has fizzeled so someone forward this if Oregen misses it .Send me a message if you cant find it

Traditional, do you think they filled the drum with dry steam or just hot air or external heat to make the steel drum hot?

Wouldn't the trum be about 4 times what I need? It's huge!

Howdy,

I am Originally from Oregon. Grew up in Eugene, and a grad of the UofO.

I was thinking a rotating furnace as probably mentioned already using exhaust from boiler through a heat exchanger

You may find this link interesting. I believe it provides you with the solution you are looking for:

http://www.altentech.com/technology.html

I have informations that this project is abandoned, so save efferts on some other problem :-((

I'm not sure where Henrik gets his 'information' from but Altentech is very active and primarily working with the goverment of British Columbia on large scale industrial wood waste moisture reduction projects.

www.altentech.com

www.bcbioenergy.ca

I mailed OP some time ago because I was curious how this project progress, and he told me it was scrapped......

Now, I am curious as to how it could be done fast and economically, because this is one of problems all would be Power plants that want to burn wood face.

But still, I feel that to burn wood for producing electricity is great waste, as it should be used to produce paper instead (at least) or any other useful thing that would bring more profit and endanger environment less.....

But, it is just my personall opinion :-))

Cliff perhaps more directly to the point Altentech Power has the technology to reduce moisture content in wood chips to 10% quickly, consistantly and cost effectively.

We are working with mills in British Columbia and the BC Bioenergy Network.

If you have specific questions we can give you detailed answers.

info@altentech.com

Cliff,

Altentech's fuel prperation system can quickly, consistantly and cost-effectively dry 60% moisture content wood chips down to even 10%. The company is very involved with the BC Bioenergy Network working with mills and biomass fueled power plants.

Boiler efficiencies will be increased over 50% and wood fibre consumed reduced by 60% plus there are significant environmental benefits.

Your answer may only be a short drive north up I-5!

If you have specific questions details can be readily available

info@altentech.com

www.altentech.com

www.bcbioenergy.ca

Hi Cliff "OT",

I have been looking into the same problem as you because in Atlantic Canada we have also wet bad weather. I am working on a briquetting plant. What I am Considering is as follows;

Hammermill chips as small as practical.

load up a single or multible silos or vertical flash dryers.

insulate them.

inside add baffles that use gravity to tumble and keep the density low enough to blow air up from the bottom."Design is key to whole thing I have some ideas"

screen type baffles may be used.

use heated air from stack or wood furnace to blow heat in near base of silo through screened side panel and screened diffuser piping inside silo.

Temper air with outside air to maintain temperature low enough not to cause fire.

maintain temperature with forced and induced blowers.

monitor humidity and advance rotary valve at bottom to drop dryed chips into boiler feed tube as chips at bottom are dryer as system causes a drying front to go up the dryer.

if one silo is dry switch to another or shut down system.

I estimate roughtly 15% of chips for system are burn in a furnace for drying system if no stack heat is used?

Any comments or advice is appreciated.

Thanks,

Robert

Hello Oregon Tinker from Philliro,

As I see it you have waste heat from turbine and stack unless you have econimizer.

calculate available btu's from waste heat.

build a silo just like a grain dryer silo. The silo has tubes going in the side and uses any number of confiqurations from a continuos coil to a ring and uprite pipes that countinue until they protrude throught the top of the silo cover. silo must have baffle arrays to keep the density of chips flowing downward from packing too tight. Drive waste heat through pipes to heat silo. Blow Heated air through a separate pipe into silo where the pipe converts into a perforated pipe array inside the silo. Vent the top of the silo and moisture is now moved out with the flow of air. A drying front will form from the bottom of the silo and moisture travels up.

A rotary valve at the bottom of cone in silo allows dry chips to drop into feed system. If you do not have enough heat to dry your chips you can use a chip furnace to supply the rest. Contact me at rcphil2@bellaliant.net for design. I ballpark guess at 60% starting moisture you will use 10 to 15 percent of wood chips in furnace to dry to 15% to 20% moisture if the furnace is all you use to dry the chips. Use dry chips in chip furnace. Drying time depends on calculations for design and please insulate the outside of everything to save heat. Build multiple silos if needed.

If this sounds like too risky for you buy an old fashion drum-dryer system but don't burn green wood!

Good luck with pitching this If you get it approved I bow to your superior political skills.

Philliro