Wood Pellets Biomass Fuel and Pellet Stoves Boilers

Archive for March, 2008

Mixing Moisture Contents

March 17th, 2008

As stated in earlier posts, the key issue that any interested small-scale pellet producer needs to address is the moisture content of their raw material. Any material to make a pellet to burn will be in the range of 10-20%. The exact moisture content is specific to that material, for example wood is generally 10-15%, but straw may require a little more than this to work well. There are purpose made material driers, but they tend to be very large and very expensive, there are more energy efficient and environmentally friendly solutions like solar driers, and I will address these in later posts.

There is another solution!

The basic problem is you have a raw material that is too moist, what you need is another raw material that is dry, to mix the two together to create a raw material of the correct moisture content. Now any biomass material can be used, but there is one material that is in vast quantities and is not fully utilized.

Cardboard

Or more specifically plain packaging cardboard, which has very little contaminates. With the vast quantities of cardboard produced, larger amounts still end up in landfill. Also cardboard cannot be constantly recycled, to make more cardboard. Once it has been recycled 3-4 times the fibres are so broken that they cannot be formed again to create a strong box. So what we are left with are vast quantities of a biomass waste material that has very little use and value, and more importantly a dry material.

At PelHeat we have made 100% cardboard pellets (see above), and they are very strong pellets, their key disadvantage is they have very high ash content, so require a lot more maintenance. Mixing cardboard with another raw material through, perhaps virgin wood could reduce the volume of virgin wood required to produce your required pellets, and you would not need to dry the virgin wood, by mixing the correct proportions of each material to get the right moisture content.

Summary

So mixing cardboard with another material could potentially solve the moisture issue and extend your raw material. You must however check waste handling and burning regulations in your area with regard to cardboard.

Thank you for your interest

www.pelheat.com

No comments »

Posted in Biomass, Making Pellets

6mm or 8mm Pellets?

March 17th, 2008

6mm or 8mm refers to the diameter of the pellet. And the general rule is as follows:

6mm Pellets: Stoves and Boilers

8mm Pellets: Boilers only

This in only a general rule, and there maybe a stove that utilizes 8mm pellets, but I have never found one.

Why have different sized Pellets?

Well to start with stoves are generally smaller than boilers, and so are their internal components. So the augur for example that feeds the pellets into the burn chamber is narrower, so can only utilize the smaller diameter pellet (6mm). Boilers on the other hand have a wider augur, so can utilize both 6mm and 8mm pellets.

Advantages / Disadvantages

For the user, utilizing 6mm or 8mm pellets there is very little difference, this is not true for the producer. You can achieve a higher productivity with 8mm pellets than with 6 mm pellets. The simple reason is that the pellet mill finds it easier to compress the material through the wider holes. So in terms of the PelHeat unit if you own a pellet boiler it makes better sense to use the 8mm die plate. Once development is finished we will have productivity figures for different material through the 6mm and the 8mm die plate, with lots of videos and pictures.