The U.S. EPA (Environmental Protection Agency) publication "AP-42, Compilation of Emission Factors" has the information you want. The publication is available online.
Go to Volume I, "Stationary Point and Area Sources" which is available at www.epa.gov/ttn/chief/ap42/index.html and then to Chapter 1: "External Combustion Sources", and then to Section 1.3: "Fuel Oil Combustion", and then to Final Section: "Supplement E".
In Supplement E, start reading and scrolling ... and you will eventually find tables listing the many various emission factors for burning diesel oil. If your boiler is in the U.S., your local air pollution regulatory agency will most probably be be using the EPA's AP-42 emission factors.
Milton Beychok
(Contact me at www.air-dispersion.com)