Posted by: Brian McMorran
Date: February 23, 2011 02:33PM
Ok lets continue the conversation about burners.
Found the original calculations for the first generator, please feel free to correct any mistakes.
I based the original calculations on the MSS II oil fired generator built by the Mobile Steam Society and described in the Steam Automobile. At the time it was my only source that described all the parameters for a generator build. Modified the figures to suit the wood pellet I intended to burn and came up with the following;
60lbs of pellet per hour at 8201 Btu/lb = 492060 Btu/hr
(492060 x boiler eff. 75%) x engine eff. 13% = 47976 Btu = 19hp
For some reason I settled on 1.76lbs of pellets per minute which a boiler engineer told me would need 9.18 lbs of air /minute, 120 cfm.
The SPAL blower specification showed 288 cfm at 70mm pressure so would have been on top of the job if I could have maintained 26 volts.
To compare; the MSS II claimed 675,000 Btu/hr input and 85% efficiency. Max. 5 U.S. gal/min, Air rate 150 cfm, combustion gas 580 lb/hr.510 lbs steam per hour.
Combustion space is the thing that has flummoxed me.I squeezed 1.02 cuft into the first generator.The oil fired Anderson generator for this engine was only 0.46 cuft, so I hoped twice this would suit the pellets. I now fear it needs closer to 1.5 cuft. More experimentation needed.
Still pondering the Lamont.