Novel riser simulator

The novel Riser Simulator is a suitable experimental tool for assessing adsorption parameters of various hydrocarbon lumps involved in the catalytic cracking process. 

Kraemer, D.W., "Catalytic Cracking in a Novel Riser Simulator Design and Testing", M.E.Sc. Thesis, The University of Western Ontario, London Ont., Canada, (1987). 

Kraemer, D.W., "Modelling Catalytic Cracking in a Novel Riser Simulator",... 

Kraemer, D.W.and de Lasa, H.I., "Catalytic Cracking of Hydrocarbon Feedstocks in a Novel Riser Simulator", Conference Proceedings, 37th Canadian Society of Chemical Engineering Conference, Montreal, P.Q., Canada, 35-37 (1987). 

Kraemer, D.W. and de Lasa, H.L, "Modelling Catalytic cracking in a Novel Riser Simulator", Paper presented at the AIChE Annual Meeting, November 27 to December 2, Washington, D.C (1988b). 

ABSTRACT. Characteristics and fluid dynamics of gas phase recirculation in a novel Riser Simulator Reactor have been investigated using constant temperature hot wire anemometry. In situ concentration and velocity measurements enabled to evaluate the mixing time and the inner recirculation ratio of the gas phase. In addition, fibre optic techniques allowed to characterize the degree of fluidization of the catalyst particles and the effect of gas phase density changes. By combining the anemometry and the fibre optic techniques, mixing patterns in the Riser Simulator have been evaluated. The importance of the study can be realized in the context of the potential use of the Riser Simulator for gas-solid reaction kinetics. 

The gas volumetric flow rate inside the annulus can also be calculated by multiplying the measured velocity by the cross sectional area of the annulus, which is 4.38 cm (refer to the column volumetric flow in Table 1), and assuming a flat velocity profile along the annulus section. For instance, knowing the volume of the lower chamber, which is approximately 20 cm then the gas can be recirculated through the lower chamber 1000 / 20 = 50 times in one second at the impeller speed of 7350 RPM (70%). It has to be mentioned that the reactor is normally operated at 7875 RPM (75%). Then a recycle rate above 50 in one second could be expected in this novel Riser Simulator Reactor. 

To this end, the Riser Simulator, a novel unit developed at CREC-UWO (1) was adapted and employed in the joint determination of these parameters. The use of accurate pressure monitoring devices allowed for good mass balances closures which in turn were crucial to the reliable determination of the other experimental parameters. 

ABSTRACT. The present contribution reviews the state-of-the-art on various aspects of catalytic cracking chemistry, catalyst formulation, catalyst preparation and FCC reactor engineering. Special consideration is given to the matters that relates to kinetic modelling. A detailed discussion is also presented on the characteristics and performance of a novel unit named Riser Simulator of particular value for FCC catalyst testing and kinetic modelling. 

The results described in this review demonstrate the importance of novel tools for kinetic modelling and catalyst development. In this context it is proposed to adopt the Riser Simulator to effectively represent the catalytic cracking reactions which take place in a FCC riser reactor. The technique allows for similar conditions to be used such as temperature, catalyst to oil ratio, partial pressure of hydrocarbons, solids loading and reaction time as those used in commercial units. Moreover, the contacting of the hydrocarbons with the catalyst is more representative of riser cracking where the catalyst moves in time with the vapours, than that achieved in the MAT test. 

It is concluded that the Riser Simulator is a suitable system for kinetic modelling of riser cracking and can also be used as a quick and reliable method for the screening of FCC catalysts. It is our view that the use of the Riser Simulator could contribute significantly to the development of novel catalysts required for the production of environmentally acceptable gasolines. 

The Riser Simulator Reactor is an internal recycle fluidized batch reactor. This patented novel device (de Lasa 1989 de Lasa, 1991), has been developed and successfully tested for the estimation of kinetic parameters of catalytic cracking of heavy oils (Kraemer and de Lasa, 1988). The details of the unit are given in the section entitled "Novel Techniques For FCC Catalyst Selection and Kinetic Modelling" by de Lasa and Kraemer in this NATO-ASI Proceedings. 

Thus, at the operational speed of 7875 RPM, the catalyst was intensively fluidized and gas was completely well mixed in the range of reaction times (1-10 seconds) expected for novel downflow reactors or riser units. In summary, this study proves the excellent ability of the Riser Simulator for catalyst testing and kinetic modelling of catalytic reactions to be conducted under short contact times. 

---