(8.2)--任务2柴油安定性.ppt

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1、Task 2 Diesel StabilityDefinitionsThe stability of diesel refers to its ability to maintain the appearance,color,composition and use performance during transportation,storage and use.The indicators for evaluating the stability of diesel include accelerated and stable sediment,iodine value,10%the res

2、idual carbon,actual gum.I.Significance of Assessing Diesel Stability The main reason that affects the stability of diesel oil is the existence of unsaturated hydrocarbon in oil products,Such as alkene,alkadiene,nitrogen compounds with sulfur and other unstable components.Using diesel oil with good s

3、torage stability can ensure the normal operation of the diesel engine.The stability of Chinas vehicle diesel oil and ordinary diesel oil are evaluated by total insoluble substances which should not be more than 2.5 mg/100 mL.Wu Xianfeng,Deputy Director-General of the Atmospheric Department of the Mi

4、nistry of Ecology and Environment said,in order to further control motor vehicle pollution and vehicle emission,the Ministry of Ecology and Environment will follow the overall plan of Blue Sky Protection Campaign-Further eliminate about 1 million diesel trucks.II.Overview of Method of determination

5、SH/T 017594 Standard Test Method for Oxidation Stability of Distillate Fuel Oil(Accelerated Method).It is suitable for evaluating inherent stability of intermediate fraction fuel oil whose initial distillation point is not less than 175 and 90%temperature is not higher than 370.A radical principle:W

6、ith no water or active metal on the surface,and no environmental factors such as dirt,increase temperature and supply oxygen to test the resistance of samples to changes when they are exposed to the atmosphere.Such ability is called inherent stability.During measurement,Inject the filtered 350mL sam

7、ple into an oxidation tube supply air at the speed of 50 mL/min.Oxidize the sample at 95 for 16 hoursand then cool it to the normal temperature.Filter it to get a filtered insoluble substance.Use the three-mixture of acetone methanol and toluene of equal volume to wash the adhesive insoluble substan

8、ce from the oxidation tube.Evaporate and remove the three-mixture to get the adhesive insoluble substance.The sum of filterable insoluble substance and adhesive insoluble substance is called total insoluble substance amount(mg/100mL).Adhesive insoluble substance means a substance that is insoluble i

9、n isooctane,which is attached to the oxidation tube wall after the sample,is released during the oxidation under test conditions.Filterable insoluble substance is a substance produced during the oxidation and separated by filtration under test conditions.It consists of two parts.One part is the subs

10、tances suspending in the sample after oxidation.The other part is substances that are easy to be washed off with isooctane on the tube wall.After oxidation of 350mL specimen,the amount of insoluble material can be filtered out according to equation(8-5).After oxidation of 350mL specimen,the amount o

11、f adhesive insoluble matter is calculated according to equation(8-6).After oxidation of 350mL specimen,the amount of total soluble matter is calculated according to equation(8-7).X=X1+X2 （8-7）III.The main factors affecting the determination (1)The catalytic oxidation of metals and metal ions Copper,

12、chromium and other metals and their ions are catalytic to the oxidation reaction,which will increase the amount of insoluble material produced.（8-5）（8-6）Clean the metal residues thoroughly before use At the same time,to prevent the residue of chromium ions,it is not allowed to wash all glass instrum

13、ents and oxidation tubes with chromic acid lotion.(2)The purity of reagents.If the purity of the three-mixture reagent is not high,there will be an increase in the amount of adhesive insoluble substances.(3)Light irradiation.Exposure to ultraviolet light will cause an increase in the amount of total

14、 insoluble substances.Samples for testing must avoid sunlight or fluorescence.All operations of such as sampling,testing,filtering and weighing should avoid direct sunlight.Preservation of the sample before oxygen supply,Oxygen supply operation.The cooling operation after oxygen supply should be carried out in a dark place.