Application Study Of Atomization Hypergravity Technology On Removal NO_x And PM From Diesel Engine Exhaust

In recent years,our country has adopted various measures to control atmospheric pollution sources,and improve the quality of the atmospheric environment.In the background of particulate matter from coal enterprises have been greatly reduced,vehicle have become an important source of particulate matter and nitrogen oxide in the atmospheric environment.Among various types of vehicle,diesel-fueled vehicles contribute far more to particulate matter and nitrogen oxide than other types of vehicles.At present,there are many problems in diesel exhaust denitrification and dedusting technology:the efficiency is easily affected by the sulfur content,the equipment investment is expensive.Therefore,the research of a diesel engine exhaust purification technology with low cost and high efficiency is an urgent problem in the current environmental protection field.Atomization hypergravity technology is a new technology for the collaborative treatment of particulate matter and gaseous pollutants.In this paper,according to studying the characteristics of particulate matter and nitrogen oxides from diesel engine exhaust,the purification device for diesel engine exhaust is designed.The purification device is composed of oxidation section,reduction section,dedusting section.Firstly,in the oxidation stage,NaClO₂ droplets oxidize and absorb NO.Secondly,in the reduction stage,Na₂SO₃ droplets reduce and absorb NO₂.Lastly,the dedusting section is equipped with a hypergravity dedusting collector to collect the particles in the diesel engine exhaust and the droplets.A demisting box is added between the oxidation section and the reduction section to collect the droplets produced in the oxidation section,to avoid the interference between two sections.Based on the characteristics of particulate matter and nitrogen oxide from diesel engine exhaust,the efficiency of different denitrification reagents is studied experimentally.NaClO₂ and Na₂SO₃ with high efficiency are selected in the purification device.The three important parameters of reagents concentration,atomization amount and residence time are optimized,and the optimal operation parameters are determined.Finally,a set of high efficiency,low cost and stable operation diesel engine exhaust purification device is designed.The main conclusions of this paper are as follows:（1）The result of denitrification reagent efficiency experiment shows that NaClO₂ and Na₂SO₃ are the best denitrification reagents in the purification device.（2）The experimental result shows that when the concentration of NaClO₂ is 0.425mol/L,the atomization amount is 22g/m³,the residence time of oxidation section is 0.07s,the concentration of Na₂SO₃ is 0.66mol/L,the atomization amount is 70g/m³,and the residence time of reduction section is 0.34s,the denitration efficiency of purification device is 80%,and the dedusting efficiency is 90%in the purification device.（3）The result of cost accounting shows that the investment cost of the purification device is 3260 yuan,and the treatment cost of exhaust from 1L diesel is 1.08 yuan.The comprehensive cost of the purification device is lower than traditional diesel exhaust treatment technologies.To sum up,the purification device based on atomization hypergravity technology can not only removal particulate matter and nitrogen oxides,but also have the advantages of simple device,low cost,easy operation,easy maintenance,which provides a new way for diesel engine exhaust treatment.