Demonstration and Evaluation of agro fuel heating
Action: Demonstration and Evaluation of agro fuel burners and boilers

The technique to burn crop is new. Today, there is no wood pellet burner who can combust crop effectively and environmentally friendly. Therefore, it is essential to design an agro pellet so that at least some of the most common wood pellet burners and hard fuel boilers can use the fuel, hence avoiding having to design a completely new combustion technique for the BIOAGRO fuel. To compete with wood chips we have to compete with a fuel price around 15 EUR per MWh or 110 EUR per ton BIOAGRO together with the fact that wood chips is easier to use. When the pellet presents an acceptable quality (in task 3) the performance when combusted will be verified. Samples will be combusted both in lab scale and at Skånefrö in two different sizes of hard fuel boilers from Hotab to decide performance, e.g. regarding production of acid and ash melting.

Methods:
A (full scale). Hotab together with Skånefrö will be responsible for this task. Hotab will initially test the agro pellets in a small hard fuel boiler (250 kW) and after that in a medium sized hard fuel boiler (1250 kW). It is important to learn from the tests of the small boiler in order to avoid having to make unnecessary modifications on the bigger boiler before demonstration. We will look at e.g silo withdrawal, transport, fuel input and ash management. The smaller boiler is a standard boiler converted to agro pellets by using a selected burner capable of handling high ash content to the fuel. The bigger boiler is a standard solid fuel boiler with a modified program for fuel with a density twice as high (density 600 kg/m3) compared with the raw material and the energy content around 4,5 – 4,6 kWh/kg. When Hotab are satisfied with the outcome of the demonstration, the combustion results will be verified and documented by Hotab and Äfab (and if necessary also by SP Swedish National Testing and Research Institute), to meet the emissions and performance according to BBR (Boverkets ByggRegler), emissions of CO solids and boiler efficiency. The choice of pellet burner functioning with agro pellets will be made by practical combustion in laboratory environment at Äfab in Lidköping. For tests at Skånefrö, Äfab testing instrument (Testo 350) will be used to measure emissions from the exhaust gases.

B (lab scale). The agro pellets will also be tested at lab-scale on real integrated multifuel boilers for domestic heating such as KWB, Baxi and Ling and in traditional underfed/burning upwards burners such as Thermis Bequeem and EcoTec A1. We will also test that the agro pellets will be functional on overfed/forward burning burners like PellX and Eurofire after some modifications, e.g. different fuel feeding speed, or minor modifications of the air feeding design. Finally, we will test the BIOAGRO fuel in a new pellet boiler, designed by Äfab for Gerkos, one of the biggest small boiler manufacturers in Ireland. The aim is to test a boiler technique that can burn pellets with higher ash content based on pellets made from other than wood.

Targets:
To make the BIOAGRO pellet work in the chosen pellet burners and boilers with a minimum of maintenance and low emissions close to what are usual for wood pellets on the market. The product shall perform the same sustainability and be as easy to fire as wood pellets and allow a fairly dustfree handling. The environmental impact from the agro pellets and the chosen hard fuel boilers  shall fulfil all regulatory requirements by a wide margin, and the economical results will give Skånefrö and other users a good profit.
Expected results:
A. We expect to demonstrate that the pellets produced in Task 3 will have an acceptable performance when burned in the Hotab boilers. This means that the combustion efficiency must be higher than 85%, that the level of emission corresponds to BBR and EN 303-5 and that the combustion does not cause unnecessary emergency stop or need of maintenance.

B. We also expect the project to succeed in producing a pellet that is possible to use in at least 20% of the domestic wood pellet burners on the market today without causing too big differences in cleaning intervals and level of reliability, hence securing a high use of the pellets produced by the agriculture sector.

Results will be documented in test reports. The test reports will include a separate section on the environmental impact.
Assumptions and Constraints:
 What limits the use of BIOAGRO is that the existing burner must deal with 7-10 times more ash than from wood pellets and an ash that melts at a lower temperature. That means that automatic removal of ash has to be installed if the firing of BIOAGRO is to be considered as comfortable as the firing of wood pellets. BIOAGRO must be made as sustainable and easy to fire as wood pellets. Previous research makes us confident that we will achieve these goals. As the Task contains many steps there is a risk that unexpected issues might delay the other steps. However, we have taken that concern into consideration by adding a “security time gap” of six months. This task is now scheduled to encompass up to 16 months which should be enough to reach the targets set.
See time schedule »»