Petroleum coke conversion behavior in catalyst-assisted chemical looping combustion

Efficiently using petroleum coke as fuel and reducing carbon emission meanwhile have become attractive in oil processing industry.The paper is focused on the application of Chemical Looping Combustion(CLC)with petroleum coke,with the purpose of investigating its combustion performance and effects of potassium.Some experiments were performed in a laboratory scale fluidized bed facility with a natural manganese-based oxygen carrier.Experimental results indicated that the coke conversion is very sensitive to reaction temperature.The pre sent natural manganese-based oxygen carrier decorated by K has little effect on the improvement of coke conversion.XRD,SEM-EDX,and H2-TPR were adopted to characterize the reacted oxygen carrier samples.After being decorated by K,the oxygen carrier's capacity of transferring oxygen was decrea sed.A calcination temperature above the melting point of K2 CO3(891℃)shows better oxygen transfer reactivity in comparison to the one calcined at a lower temperature.The natural oxygen carrier used in the work has a high content of Si,which can easily react with K to form K(FeSi2 O6).Further,irrespective of reaction temperature,the coke conversion can be significantly enhanced by decorating the coke with K,with a demonstration of remarkably shorter reaction time,faster average coke gasification rate and higher average carbon conversion rate.

An image processing method for feature extraction and dynamic tracking of particle clusters in CFBs

A new image processing method based on the high-speed camera is proposed to identify,locate,and track clusters.The instantaneous characteristic parameters of particle clusters in the riser of the circu-lating fluidized bed(CFB)can be acquired,such as solids holdup,vertical velocity,lateral displacement,aspect ratio and near-circularity.Experiments were carried out with glass bead particles,river sand particles and FCC particles.The time series of images of gas-solid flow in a CFB riser with a 100 mm x 25 mm cross-section and 3.2 m in length were obtained using high-speed cameras.The k-means++clustering algorithm is utilized to identify the clusters,centroid is applied to locate the clusters,and the cross-correlation algorithm is employed to track the specific clusters and number them to get the instantaneous characteristic parameters.The results illustrate that the shapes of clusters in the center area are closest to circle,moving upwards at a uniform speed,while the clusters in the side-wall area are mostly elongated or long chain-like,moving slowly downwards.In the transition area,the clusters are more complex,moving upwards at a constant speed,and having large lateral displacement.The results show that the image processing method used in this study is successful in acquiring the dynamic and structural parameters of the clusters simultaneously.