Study On Chemical Agglomeration Of Dust For Electrostatic Precipitation Technology

In recent years,haze weather occurs frequently,coal burning pollution is becoming more and more serious.It does great harm to human health.It is necessary to develop a new type power generation technology and realize clean utilization of the coal in order to alleviate this situation.Coal gasification technology is an effective means to realize clean utilization of the coal.However,gas from the producer contains a large amount of particulate matter,which will cause damage to the generator set directly.Therefore,it needs to be purified by a dust removal equipment.The existing wet type purifying process has low collection efficiency and massive water consumption.The electrostatic precipitator is recommended to use for its high efficiency in order to replace the traditional wet process.On the reason that the dust particle size from the gas producer is too small,it is difficult to be purified by the electrostatic precipitator,chemical agglomeration technology can be used in the electrostatic precipitator to solve this problem.It can effectively promote dust agglomeration without changing normal production conditions or existing dust removal equipment.Therefore,the chemical agglomeration technology used in the integrated combined cycle(IGCC)purification system is presented in the paper.And the factors affected by the chemical agglomeration is discussed.The physical and chemical properties of gasifier dust are analyzed and the influence factors of chemical agglomeration on corona discharge performance of dust from the gasifier are investigated in the paper.The results show that:dust from the gasifier is dominated by these elements,such as C,O,and Fe.The median diameter of dust is 23.25μm.Its specific surface is about 7.8 m~2/g.Its specific resistance range is between 10~4～10~6Ω·cm.Chemical agglomeration agent xanthan gum(XTG)works the best.Turbulent mixing effect spraying at the inlet box position is the best.The agglomeration and charging performance which selected solid cone type nozzle is the best.Chemical agglomeration has effects on the corona discharge performance of dust from the gasifier.adding agglomerating agent,surfactant and increasing the concentration of surfactant can reduce the spark voltage.While using the four tooth barbed wire and adding graphite powder in the agglomerating agent can expand the corona discharge range of the dust from the gasifier and increase the discharge current.The properties of agglomerate have effect on the dust removal efficiency.When the agglomerating agent is XTG,the concentration of agglomerating solution is 0.1 g/L,and Tween 80 is used,the dust removal efficiency is the highest.The dust removal efficiency can be further improved by adding a certain concentration of phosphoric acid into XTG.The operating conditions have influence on the dust removal efficiency.When the electric field voltage is 40 k V,the flow rate is 1.5 L/h,the electric field gas speed is 1.0 m/s,the dust concentration is 180 mg/L,and the electrode type is fish bone wire,the dust removal efficiency is the highest.It is also the highest when adding chemical agglomerating agent at the inlet box.When the gas speed is more than 11.2 m/s,adding chemical agglomerating agent at the middle section,the dust removal efficiency where the angle of attack is 180°is bigger than that is 90°.The voltage has little effect on the turbulent mixing.The dust removal efficiency at the three locations increases with the concentration of agglomerate solution and injection flow rate.The coordination of water mist charging has effect on the dust removal efficiency.When the water pressure is 0.5 MPa and the solid nozzle is selected,dust removal efficiency is the highest,and it is 99.12%.The addition of specific resistance regulator has effect on the dust removal efficiency.After adding graphite powder into agglomerate XTG,the efficiency of dust removal can be improved to 90.28%.It is solved by using the technology of chemical agglomeration to promote the precipitation efficiency of the dust from gasifier because the dust which has small particle size is collected by the electrostatic precipitator.It provides a new idea for the purification of the gas from gasifier in China.The research also provides a theoretical and technical reference on the industrial application of electrostatic precipitator for the purification of gasifier dust.