"The excellent qualities of the wood-pellet have led to high quality domestic automatic stoves and boilers being developed. A large market for these appliances and the wood-pellet fuel for them has developed both in Northern Europe and in the Northern part of the North American continent. The wood-pellet sets a very high standard for other bio-fuel pellets. [These are normally termed agri-pellets].

There are technical problems with burning agri-pellets in equipment developed for using wood-pellets. The main problems are:

o The high ash content relative to wood-pellets.[10 times more]
o Problems with slagging [sticking together] of the ash.
o Higher wear in the pelletising machinery.

Straw contain potassium and sodium compounds. These alkali compounds are present in all annual crops and crop residues in particular. During combustion, alkali combines with silica and causes slagging and fouling problems in conventional combustion equipment designed for burning wood at higher temperatures. Volatile alkali also lowers the fusion temperature of ash: in conventional combustion equipment having furnace gas exit temperatures above 800°C, combustion of agricultural residue causes slagging.

It is therefore not easy to generate a market for agri-pellets until stoves and boilers are developed for home usage of these pellets as a domestic fuel. The home heating market is where the highest added value is available".

The CARBOROBOT is specially designed boiler for high ash content agripellet, with lower temperatures of fuel layer on the rotary grate, and it can reduce slagging and fouling of these fuels. Practically the slagging of the ashes of the agripellets not (or at very low level) and the CARBOROBOT boilers can operate with agripellets without additives.

The ash removing from the burning zone is automatical. By the Classic and the Farmer types the ash cleaning from the boiler is manual. The Automat types have a special ash remover system, what can remove automatically the ash to the external ash bin or container.