典型工業(yè)粉體的料倉下料特征及優(yōu)化研究
發(fā)布時間：2018-11-25 07:05
【摘要】：以氣流床粉煤加壓氣化技術供料系統(tǒng)中的鎖斗下料環(huán)節(jié)為研究背景,利用有機玻璃料倉常壓下料系統(tǒng),研究了多種工業(yè)氣化粉體的通氣下料流動情況。通過FT4、粒度儀等測量了晉城煤、羊場灣煤及石油焦三種典型工業(yè)粉體的物性參數(shù),經粉體間Carr流動性指數(shù)、HR(Hausner Ratio)指數(shù)等物性參數(shù)的對比后發(fā)現(xiàn)所用工業(yè)粉體均有流動性較差,黏附程度較強的共性,綜合比較后發(fā)現(xiàn)HR指數(shù),Carr指數(shù)及剪切特性是預測粉體在料倉內流動的有效參數(shù)。借助于稱重模塊、壓力傳感器及ECT(Electrical Capacitance Tomography)等測量手段,歸納并總結了不同粉體所表現(xiàn)出的下料特征現(xiàn)象。分析壓力信號變化時發(fā)現(xiàn)倉內粉體靜置時間能夠嚴重影響粉體的重力下料過程;通氣對促進粒徑較小、黏附性較強粉體下料流動更為有效。對于流動性稍好的粉體,下料初期的料倉壁面的壓力增加幅度更高,而下料過程中在料倉錐口壁面附近又會產生持續(xù)負壓狀態(tài)。分析ECT信號變化可知,下料后粉體在豎直管內流型一般呈環(huán)核流形式,粒級較大粉體流動連續(xù)性好,顆粒運動過程不易受通氣影響;黏附性較強粉體則會出現(xiàn)管內流型向滿管流的轉變。由粉體堆積性質及下料現(xiàn)象提出了粉體下料過程中存在臨界堆積強度,粉體整體堆積強度小于臨界強度時下料才會發(fā)生,通氣的作用之一在于下料前降低倉內粉體堆積強度。結合流化床中的氣泡運動理論,建立了以氣相運動角度描述顆粒下落運動的下料分區(qū)模型,解釋了通氣下料流率拱形變化曲線、氣壓平衡拱等現(xiàn)象�；趯嶒灁�(shù)據關聯(lián)氣泡尺寸與通氣高度及通氣氣速間的關系,通過分區(qū)模型分別計算了工業(yè)粉體最優(yōu)相對通氣高度H/D=12.25和最優(yōu)通氣氣速U_g=1.58 m·s~(-1)即2.4Umf。模型計算值與實驗值的吻合效果良好,在5.56H/D18、U_gUmf的范圍內,下料流率的計算偏差小于±20%。證明了優(yōu)化方法的有效性。
[Abstract]:Based on the research background of the locking hopper in the feeding system of pressurized pulverized coal gasification with airflow flow of various industrial gasification powders was studied by using the normal pressure discharge system of organic glass bunker. The physical properties of three typical industrial powders, Jincheng coal, Yangchang Bay coal and petroleum coke, were measured by FT4, granularity analyzer. The Carr fluidity index between the powders was also measured. The comparison of physical property parameters such as HR (Hausner Ratio) index found that the industrial powder used has the commonness of poor fluidity and strong adhesion. After comprehensive comparison, the HR index was found. Carr exponent and shear characteristic are effective parameters to predict the flow of powder in silo. By means of weighing module, pressure sensor and ECT (Electrical Capacitance Tomography), the characteristics of different powders are summarized and summarized. When the pressure signal changes, it is found that the static time of the powder in the silo can seriously affect the process of gravity blanking, and the aeration is more effective to promote the flow of the powder with smaller particle size and stronger adhesion. For the powder with better fluidity, the pressure on the wall of the silo at the initial stage of blanking is higher, and the continuous negative pressure will occur near the wall of the tapered opening of the silo during the process of blanking. By analyzing the change of ECT signal, it can be seen that the flow pattern of the powder in the vertical tube is generally in the form of annular nuclear flow, the flow continuity of the larger particle size is good, and the particle movement process is not easily affected by aeration. The strong adhesion of the powder will lead to the change of the flow pattern to the full flow in the tube. According to the properties of powder stacking and the phenomenon of blanking, it is pointed out that there is critical stacking strength in the process of powder blanking, and when the overall stacking strength of powder is less than the critical strength, the effect of aeration is to reduce the stacking strength of powder in silo. Based on the theory of bubble motion in fluidized bed, a cutting zone model is established to describe the falling movement of particles from the angle of gas movement, and the phenomena such as the arch curve of flow rate under ventilation and the equilibrium arch of air pressure are explained. Based on the experimental data, the relationship between bubble size and ventilation height and velocity is correlated. The optimal relative aeration height (H/D=12.25) and the optimal aeration velocity (U_g=1.58 MS-1) of industrial powder were calculated by using the zoning model, i.e. 2.4 Umf. respectively. The calculated value of the model is in good agreement with the experimental value. In the range of 5.56 H / D 18 UgUmf, the deviation of calculation of discharge rate is less than 鹵20. The effectiveness of the optimization method is proved.
【學位授予單位】：華東理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ546;TB44
本文編號：2355211
[Abstract]:Based on the research background of the locking hopper in the feeding system of pressurized pulverized coal gasification with airflow flow of various industrial gasification powders was studied by using the normal pressure discharge system of organic glass bunker. The physical properties of three typical industrial powders, Jincheng coal, Yangchang Bay coal and petroleum coke, were measured by FT4, granularity analyzer. The Carr fluidity index between the powders was also measured. The comparison of physical property parameters such as HR (Hausner Ratio) index found that the industrial powder used has the commonness of poor fluidity and strong adhesion. After comprehensive comparison, the HR index was found. Carr exponent and shear characteristic are effective parameters to predict the flow of powder in silo. By means of weighing module, pressure sensor and ECT (Electrical Capacitance Tomography), the characteristics of different powders are summarized and summarized. When the pressure signal changes, it is found that the static time of the powder in the silo can seriously affect the process of gravity blanking, and the aeration is more effective to promote the flow of the powder with smaller particle size and stronger adhesion. For the powder with better fluidity, the pressure on the wall of the silo at the initial stage of blanking is higher, and the continuous negative pressure will occur near the wall of the tapered opening of the silo during the process of blanking. By analyzing the change of ECT signal, it can be seen that the flow pattern of the powder in the vertical tube is generally in the form of annular nuclear flow, the flow continuity of the larger particle size is good, and the particle movement process is not easily affected by aeration. The strong adhesion of the powder will lead to the change of the flow pattern to the full flow in the tube. According to the properties of powder stacking and the phenomenon of blanking, it is pointed out that there is critical stacking strength in the process of powder blanking, and when the overall stacking strength of powder is less than the critical strength, the effect of aeration is to reduce the stacking strength of powder in silo. Based on the theory of bubble motion in fluidized bed, a cutting zone model is established to describe the falling movement of particles from the angle of gas movement, and the phenomena such as the arch curve of flow rate under ventilation and the equilibrium arch of air pressure are explained. Based on the experimental data, the relationship between bubble size and ventilation height and velocity is correlated. The optimal relative aeration height (H/D=12.25) and the optimal aeration velocity (U_g=1.58 MS-1) of industrial powder were calculated by using the zoning model, i.e. 2.4 Umf. respectively. The calculated value of the model is in good agreement with the experimental value. In the range of 5.56 H / D 18 UgUmf, the deviation of calculation of discharge rate is less than 鹵20. The effectiveness of the optimization method is proved.
【學位授予單位】：華東理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ546;TB44
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