Preliminary Study On The Emissions Test Of Offshore Fishing Vessels

Compared with standard emission measurement system,the measurement accuracy and stability of PEMS（Portable Emission Measurement System）are questionable.This paper compared and analyzed the test differences between the PEMS and the standard emission analyzer under the transient and steady conditions of diesel engine on the engine test bench.The bench test was based on a non-road four-stroke direct injection supercharged diesel engine（National Stage III）,the PEMS adopted AVL M.O.V.E PEMS,and the standard emission analyzer used the HORIBA MEXA system.In the bench test,the PEMS and HORIBA system simultaneously collected the instantaneous concentration of engine exhaust pollutants,and combined with the engine operating condition parameters（speed,power,etc.）to calculate the power-based weighted emission factors（g/kWh）.The test results showed that under transient condition,the test differences of the components from large to small are CO,CO₂,THC,NOx,and PN,which are 12.78%,11.31%,8.06%,6.44%,and 2.02%respectively.Under steady condition,the test differences of each component from large to small are PN,CO,CO₂,THC,and NOx,which are 36.91%,15.69%,10.62%,10.35%,and6.85%respectively.The difference of gaseous components by different test equipment is small and relatively stable,and the test difference of PN is large and unstable.The engine load also has a great influence on the test difference of the equipment.Under low load,the test difference of CO,THC,CO₂ is large,and under high load,the test difference of NOx and PN is large.Based on the results of PEMS comparative test,six representative fishing vessels in Beihai,Guangxi Province were tested under typical conditions,and the emission factors of offshore fishing vessels were obtained,and the emission factors of CO₂,CO,NOx,THC,PM based on fuel consumption were 3400.93,44.59,84.82,19.69 and 10.23 g/kg fuel.Because Chinese marine fishing vessels are mainly offshore fishing vessels,the marine fishing vessels Emission Inventory can be calculated based on the emission factors of offshore fishing vessels and the total fuel consumption of Chinese marine fishing vessels.In 2018,the total emission of CO₂,CO,NOx,THC,and PM of Chinese marine fishing vessels were 305.15×10⁴t,4.01×10⁴ t,7.61×10⁴ t,1.77×10⁴ t and 0.92×10⁴ t.In order to explore the actual effect of biodiesel on energy saving and emission reduction of ships,PEMS test comparison tests of B0（petrochemical diesel）,B50（diesel and biodiesel each account for 50%of the volume）and B100（biodiesel）were carried out.The test results show that B50 can reduce the emission factors of CO,THC,PM and CO₂ of ships by 45.60%,47.48%,28.30%and 0.88%respectively,but the emission factor of NOx increases by20.12%.