Cannot help with a machine model, but while I understand the palletizing issue, the end user may have issues with that hollow form. The hollow log will burn much faster than a solid round one if that is important. For people looking to fuel furnaces the shape is not optimal for packing the combustion chamber for a long slow burn.
If you want to produce solid brick like units may I offer the possibility that you may be able to expand your machine search to include cement/masonary brick and block making machines. They extrude cement mixtures under presure and then wire or knife cut them to units.
Would concrete block forming equipment produce enough pressure to bind the sawdust without using some time of adhesive in the mixture? From my understand, the lignin will bond sawdust together when exposed to high pressure. The hollow form isn't really important. I just like the rectangular shape since it's easy to stack on a pallet.
I doubt very much that an extruder for cement or any other type of product will work for briquettes. It takes much more pressure than an open ended extruder can produce. Every briqutte machine I looked at needed a "head" to push against to produce the required pressure.
In modern wood burners or boilers with controled dampers I don't think the design of the briquette makes any difference, hollow or solid.
You are correct about lignin bonding under pressure. No additives needed. Moisture content is also an issue. From my research 12-13% mc is the best. I make briquettes in my Wiema with 8% mc dust and it works fine for my use.
Do a google search and see what you can find. Weima, Ruf, Stiles and North Tech are a few for starters.
I just remembered that the machine Stiles sells is an open ended machine. It compresses against a cone shaped die thus producing an extruded briquette. I looked at it at the AWFS or IWF 2-3 years ago. Very nice machine but way too high production and priced for me. It made a round briquette.
I have a couple of different purposes for briquettes. We're in the process of developing a waste fired boiler that will provide steam for our vacuum kiln and produce our own current. There is also a very good market for fire starter logs. We produce a tractor trailer load about every 3 days.
If you use a tub grinder, you have to cut the rippings. A horizontal grinder with a vibrating conveyor can be placed next to the rip saws and no further handling/storage is required. Many good grinders available. Had good luck with Cresswood.
We have used a briquette machine for a few years. Our machine is a Comafer made in Italy.
I would recommend going with a machine that has support and service in the US.
The square bricks are better and easier to store. The machines that make square usually cost more.
The hollow center should cause no problem and will probably burn better. You cannot compare briquettes to logs.
If you have a moulder the briquetter would need 200 to 250kg per hour capacity minimum to keep up. At your volume probably a lot more. At a trailer load every 3 days it might be more cost effective to go with a silo that feeds a sawdust burning boiler. The European companies bringing in briquette machines usually offer these systems also.
as for as i know , the best machine to make biomass briquettes is "plug and press" type briquette machine which is durable , efficient,etc The most important is , this kind of machine is suitable for most raw materials such as woodwaste, agri-forestry wastes, plastic ,etc. please contact me to know more details : firstname.lastname@example.org 0086-18766117903
Below pics is the type of briquetter that can be used for briquetting with this shape.
It is also called pini-kay shape in the world somewhere.
You may find more specifications through the Maxton's website and may find other briquetter that is also useful for sawdust.
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