Figure 5-1 Fuel mass flow vs . biodiesel content .

has sulfur levels typically under 10 ppm and so sulfur dioxide emissions are reduced compared to home heating oils with higher sulfur values . Although NOx emissions are not regulated and are not normally monitored or measured for home heating oil applications , in many tests in boilers and furnaces flue gas NOx levels were found to be reduced with biodiesel but some results were reported to be similar to those with No . 2 fuel oil . Smoke and CO emissions are typically as low or lower than with petroleum No . 2 heating oil .

During this project , additional experimental data was obtained specifically on the impact on combustion , excess air values , and flame sensor sensitivity to changing biodiesel content in delivered fuels . As an oxygenated and ultra-low sulfur fuel , biodiesel typically requires less combustion air and burns with less particulates than conventional No . 2 fuel oil . A conventional cast iron home

heating boiler and a common retention head oil burner and cadmium sulfide flame sensor were used in these tests . While there are some small technical differences from manufacturer to manufacturer , this system is a good example of the vast majority of systems in the home heating oil market in the US . A fresh sample of B100 meeting ASTM D6751 was provided by a major biodiesel producer for these tests .

The fuel system was arranged with split suction so that the test fuel could be changed without shutting down the burner . Test fuels were located on lab balance for direct measurement of the mass flow rate . During these tests , the burners safety control was bypassed to enable direct measurement of the cadmium sulfide photoconductor resistance . With the common burner control used in these tests , a resistance level under 1600 ohms in steady state is associated with proper performance .

The testing was done in two phases . In the first , the burner excess air value was tuned as is normally done for a home heating oil system ( i . e . low CO and smoke number ) and set at approximately 4.75 % excess oxygen ( 27 % excess air ) based on operating in steady state with B0 . After this , the biodiesel blend level was changed and combustion performance measurements were made keeping the air flow control damper position fixed . This would simulate a home setup and running on conventional No . 2 oil switching to the higher blends without making any adjustment in the flame sensor operation or excess air setting .

In the second phase , the burner operated on just B100 . The burner ’ s air shutter setting was then changed to evaluate the impact on the flame sensor resistance as a function of flue gas O2 measured in the exhaust .

RESULTS

Figure 5-1 shows the impact of biodiesel blend level of fuel mass flow and shows an increase with increasing biodiesel content . It is well known that these nozzles have higher mass flow with higher fuel viscosity and this is likely the cause of this small increase . l FON

( This excerpt to be continued in the May 2019 issue .) www . yourfuelsolution . com ( 978 ) 258-8360

NEXT-GENERATION PERFORMANCE ADDITIVES

detergents + stabilizers + cold flow improvers + biocides moisture control + lubricity agents + corrosion inhibitors

ulsd • ulsho • biodiesel blends • marine fuels • gasoline

14 APRIL 2019 | FUEL OIL NEWS | www . fueloilnews . com