BIOMASS DRYING

I have touch on this topic in December 2010 in the title of Sawdust Drying . In many cases material needs to be  dried to certain acceptable  Moisture Content before it can proceed to the next stage of manufacturing  . 

In my visits to many plant , I have seen too many mistakes made in the selection of drying system , either wrong fuel are used , wrong design of furnace , wrong design of dryer , wrong design of conveying system for input and output of materials and etc . This mistakes cause many other problems down the line especially during pelletisation not mentioning high cost of drying . Make no mistake , you cannot have good system if you do not have proper knowledge of drying and combustion . That is why drying system are expensive because it will saves you money later and in some cases a matter of do or die . 

Drying Efficiency

Drying for pelleting process are normally done with direct chanelling of hot flue gas into the drum dryer where the hot air are in direct contact with the material to be dried . This process of direct contact are of highest efficiency as compared to indirect heating with a heat exchanger . Depending on material , moisture content of the material and structure of the material , the hot flue gas input temperature can be as high as 800º celcius . The higher the temperature , the faster the material are being dried and you will get higher output from the drum dryer otherwise the drying section will become bottleneck . Consistent temperature from the furnace to the dryer are also important so that the Moisture of Biomass dried is consistent . To achieve consistency and narrow range of Moisture , firing into furnace or dryer need to be consistent , this can be achieve by having good Burner .

Drying Cost

Many  a times this was overlook , everything we sell have a selling price and it also come with a cost . Similarly in wood pelleting , there is cost to manufacturing of wood pellet , and to those who use wet sawdust or even EFB , there will be need for drying , this is one section which is often overlook . Good cost structure will be drying cost of below RM20 / MT of dried raw material . How do we achieve this : 

1 ) use low cost material like timber offcut , woodchip , EFB , Palm Fibre etc

2 ) use high efficiency pellet burner because you are producing pellet 

3 ) do not use electricity , gas or diesel burner , you calculate the cost yourself to find out 

That being said , the planning of Good Drying System is pertinent to keep the cost low so that there will be profit in the selling of pellet . If you dry your material above RM50 / MT then this business will be unprofitable . 

In short it is not easy to keep cost low as currently for any fuel there is cost involved , selection of correct drying system are important .

Drying Quality

During pelleting process , consistent Moisture Content of material input are important to give consistent quality of pellet output , otherwise one minute you will get good and the next minute bad quality pellet . Therefore dryer must have flexibility to ensure Consistent MC for biomass output from dryer .

For your information , any sawdust or even EFB will have sand and stone in it , too much of it will increase the ash content of pellet and thus pellet price will be affected . A good dryer will have system to remove partial of the sand and stone . Removal of sand and stone will also prolong the life of roller and die during pelleting process . 

3 of the above factor are important in the selection of the correct dryer . Wrong selection will cause the followings : 

1 ) Under or Over Capacity of dryer 

2 ) Low temperature input will cause slow drying 

3 ) Inconsistent temperature cause fluctuation in drying thus MC of biomass dried will not be consistent 

4 ) Wrongly build furnace do not give enough heat input to dryer causing under utilisation of dryer 

5 ) Wrong air flow of hot flue gas are not sufficient for drying of biomass 

6 ) Wrong design of input and output conveyors reduce the efficiency of drying

7 ) Non Flexibility of dryer controller make it difficult to get good drying results

8 ) Wrong biomass used for firing , increase cost of drying , whole project not viable 

9 ) Manual feeding of biomass fuel in big furnace are not recommended as labour incur cost and optimum drying are not achieved 

10 ) Inconsistent MC of biomass dried cannot be pelletise into good quality pellet 

11 ) Too much sand and stone will jam the Pellet Mill and damage other parts

and many many more .

Make sure Dryer are selected correctly .

QC and R & D

Quality Control and Research and Development Programme 

Manufacturing is define as : 

The process of converting raw materials , components or parts into finished goods that meet a customer's expectations or specifications .

That being said , I would like to add , to be able to make profit the whole process is a race against time to reach optimum level of operation in shortest possible time .

As of now I believe there are more than 10 wood pellet plant in Malaysia , probably over half have difficulties in producing high quality pellet and running at low efficiencies . Some are not running at all . I admit mine are also having problems with breakdown here and there , but importantly improvement are carried out after each obstacles thus weakness becomes strength .

Wood Pelleting are more an arts rather than skill . There are just too many variables especially for China Made Machines . 

Unless and until you get all the parameter right , it is near to impossible to get high efficiency and quality .

In many organisation QC and R & D are lacking especially in the SME . This is the nature of business as it is too costly to setup and followup . But without these you would be FLYING BLIND , that is what happen and the blame is simple , on the machine . No doubt , China Machine is bad but there are ways to go around to get it better . Unless you are willing to invest in American or European Machines which will cost a bomb .

In wood pelleting , the person in charge MUST be able to setup proper recording so that improvement can be carried out . Proper records are just like a GPS in a foreign country . You use it ( the records ) to see : 

1 ) Who can help 

2 ) What happened 

3 ) Where are you now and where are you going 

4 ) When can you arrive 

5 ) Why things happen 

6 ) How did it happen 

Remember the 5 W's and H

!! GHOSTBUSTER !!  SOUNDS FAMILIAR

Imagine that you are starting , you get into problem , the supplier of the machines did not give correct procedure ( friend , they are seller of machines , they will promise you sky to sell , they are not production man , how do you expect them to give full range of advice when we are paying pittance for the machines ) and your machine are damage or you are running at very low effciency .

What do you do ???

You try and try , after 2 months time loss you give up , losses amounts to RM50,000 or more , you still want to carry on but do not know where to start and when can solve all this problems . Sounds very familiar , it happen to me too !!

What do you do ??? or better WHO YOU GONNA CALL !!! GHOSTBUSTER  , CALL ME .

For now enjoy the song & video .

Word of  Advise , if you are not able to solve the problems in 2 months , it is not possible for me to solve it by phone , it is just impossible , there are just too many parameters and you will need tools to help just like the GPS .

With all the advice and tools hopefully you are on the way for higher efficiency and higher quality of wood pellet . 

Many people called but are unwilling to pay ( no free lunch ) , so advice from the phone are limited in quality , they try the method advised still doesn't work , it won't work , we take 6 months of blood sweat and tears to perfecting our method , so with 30 minutes advise you expect it to work , I wish how simple it is .

In fact I would advise , after you have commission your machine and it does not perform to expectation within 2 weeks ,  better call me immediately for consultation , if not you will lose 2 months at least and over RM50,000 for trial and error . 

WHO YOU GONNA CALL !!!

Drum Dryer

Sawdust Drying

We are touching this topic specifically due to it's importance to make good wood pellet unless your sawdust is already dried to 15% Moisture Content ( MC ) .

If you have gone through our earlier writings , the cost of drum dryer are significant for a Whole Line Wood Pellet Plant . The High price are due to it's big structure and complication in maintaining stable MC sawdust output . Sawdust comes in various MC from 12% to 60% , therefore it is important to control the MC for optimum pelleting otherwise you would not get high standard wood pellet and high production efficiency .

We will now study a typical drying process base on the following conditions :

1 ) Input Sawdust MC 35%

2 ) Output Sawdust MC 12%

3 ) Drying Rate 2 Ton Per Hour Output

To reduce MC from 35% to 12% you would need to evaporate 20% of water , based on 2,000 kg per hour output , water that need to be removed is 600kg and the input sawdust is 2,600 kg/hr .

To remove 600kg of water you will need 640kw ( 550,000 kCal/hour ) of energy which is equivalent to burning 200kg/hour of wood offcut . In short 100kg/hour need to be combusted to dry 1 TPH ( output ) sawdust . Cost of drying would be about RM5 / ton sawdust if your offcut cost is RM50 / ton .

The Calculation Chart below is from ASPENTECH software and reconfirm by manual calculation which I did not show here due to it's tediousness of calculation , suffice to say the input data , output data and design of the dryer are correct .

Drum Dryer selection are important , many factor affect the cost of the dryer , in this case we believe Drum Dryer Size of Diameter 1.5 meter X Length 9 meter should be enough to dry 2 TPH of sawdust .

Cost of this dryer should be around RM200,000 landed in Malaysia c/w stove , electrical panel and cyclone .

We hope to use this Dryer and the Pellet Mill to make EFB Pellet once we have started Wood Pellet Production probably in August 2011 .