Combustion of biodiesel in a large-scale laboratory furnace

•CO emissions from biodiesel and diesel tested are similar.•NOx emissions from biodiesel tested are lower than those from diesel tested.•Diesel tested yields significantly higher PM (particulate matter) emissions than biodiesel tested.•Diesel tested originates PM with Cr, Na, Ni and Pb, while biodiesel tested produces PM with Ca, Mg and Fe.

Combustion tests in a large-scale laboratory furnace were carried out to assess the feasibility of using biodiesel as a fuel in industrial furnaces. For comparison purposes, petroleum-based diesel was also used as a fuel. Initially, the performance of the commercial air-assisted atomizer used in the combustion tests was scrutinized under non-reacting conditions. Subsequently, flue gas data, including PM (particulate matter), were obtained for various flame conditions to quantify the effects of the atomization quality and excess air on combustion performance. The combustion data was complemented with in-flame temperature measurements for two representative furnace operating conditions. The results reveal that (i) CO emissions from biodiesel and diesel combustion are rather similar and not affected by the atomization quality; (ii) NOx emissions increase slightly as spray quality improves for both liquid fuels, but NOx emissions from biodiesel combustion are always lower than those from diesel combustion; (iii) CO emissions decrease rapidly for both liquid fuels as the excess air level increases up to an O2 concentration in the flue gas of 2%, beyond which they remain unchanged; (iv) NOx emissions increase with an increase in the excess air level for both liquid fuels; (v) the quality of the atomization has a significant impact on PM emissions, with the diesel combustion yielding significantly higher PM emissions than biodiesel combustion; and (vi) diesel combustion originates PM with elements such as Cr, Na, Ni and Pb, while biodiesel combustion produces PM with elements such as Ca, Mg and Fe.