Riser simulator

Figure 2.3.2 (Kraemer and deLasa 1988) shows this reactor. DeLasa suggested for Riser Simulator a Fluidized Recycle reactor that is essentially an upside down Berty reactor. Kraemer and DeLasa (1988) also described a method to simulate the riser of a fluid catalyst cracking unit in this reactor.

The riser is a vertical pipe. It usually has s 4- to 5-inch (10 to 1" cm) thick refractory lining for insulation and abrasion resistance. Typical risers are 2 to 6 feet (60 to 180 cm) in diameter and 75 to 120 feet (25 to 30 meters) long. The ideal riser simulates a plug flow reactor, w here the catalyst and the vapor travel the length of the riser with minimum back mixing. 

The thermal and catalytic cracking of PP, PS, and SBR waste, dissolved in light cycle oil, was studied in a riser simulator. 19 refs. 

Several different reactor types were used for catalyst evaluation, including a DCR pilot riser [3] an ACE fixed fluidized bed (FFB) reactor [7], a Riser simulator [4,9], and a specially designed extended residence time circulating pilot unit. The reaction conditions of each of the reactors will be reported in the sections dealing with the specific reactor type. Different grades of Brazilian Campos Basin derived VGOs were used in the experiments. Feed properties are presented in Table 2.1. 

To evaluate the new process conditions that would allow the MAB catalyst to produce lower slurry oil yields than those obtained in the FEB unit, a series of experiments were carried out using a Riser Simulator—built and perfected at the Institute of Petrochemistry and Catalysis Research (INCAPE/FIQ-UNL) in Santa Fe, Argentina (Figure 2.11). 

In the Riser Simulator, an impeller rotating at very high speed on the top of the reaction chamber keeps the catalyst fluidized between two metal porous plates, inducing the internal circulation of the reacting mixture in an upward direction through the chamber. When the reactor is at the desired experimental conditions, the reactant is fed through an injection port, and immediately after the set reaction time is attained, products are evacuated and analyzed by gas chromatography. Of particular importance to the experiments performed was the ability to extend reaction... 

FIGURE 2.11 Riser simulator reactor schematics, showing reaction chamber at left and peripherals at right, including a preheated vacuum cylinder linked to a gas chromatograph to drain, quantify and identify reaction products at the end of a rnn. 

Tables 2.1 and 2.4 show the VGO-C feed quality properties and the test conditions of the Riser Simulator experiments. The three catalysts tested were the same ones used in the FFB reactor experiments. Temperature for the LZM catalyst was lower than for the other catalysts to reproduce typical conditions used for mid-distillate maximization in commercial units.

In the Riser Simulator it was possible for the MAB catalyst to reach slurry oil yield levels compatible with the conventional LZM catalyst operating at typical conditions for maximum mid-distillate. However, the yields of heavy naphtha range aromatics were half of those obtained with the LZM catalyst compared at the same slurry oil yield (Figure 2.12). The MAB ClO-Cll aromatics trend as a function of slurry oil yield was a continuation of the inert catalyst trend, an indication that a similar reaction mechanism could be taking place. The minimum slurry oil yield for the inert catalyst, even at maximum severity, was still above 40 wt% ... 

FIGURE 2.12 Riser simulator results Heavy naphtha aromatics (ClO-Cll) as a function of slurry oil yield (343°C+) (X) Inert, ( ) LZM catalyst, (a) MAB catalyst. 

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. 

PRUSKI ET AL. Riser Simulator Testing of Adsorption Effects... 

A typical pressure profile obtained from the two transducers is presented in the Figure 2. Curve I along with points A, B and C illustrates the characteristic pressure prorile observed during the operation of the reactor. Meanwhile, curve II depicts the pressure profile inside the vacuum chamber. Point A of curve I indicates the pressure condition inside the Riser Simulator just prior to the hydrocarbon injection. Point B gives the Riser Simulator pressure at the end of the reaction period (just before evacuation commences) and Point C represents the equilibrium pressure once the pressures between the vacuum chamber and the Riser Simulator have stabilized. 

Figure la. Schematic of the Riser Simulator with a general view of the unit... 

Figure lb. Riser Simulator Components reactor, vacuum box, glass chamber... 

Figure 2. Curve I Riser Simulator Pressure. (A) Prior to Injection, (B) Before Evacuation, (C) Equilibrium Pressure. Curve II Vacuum Chamber Pressure.

At the same time, the total pressure in the vacuum chamber during pressure equalization as well as in the Riser Simulator during reaction is the sum of the partial pressure contributions of the various lumps ... 

Thus, by combining Equations (1-4) the total pressure rise inside the Riser Simulator can be represented by the following equation ... 

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

Figure 3.13 Scheme of a riser simulator reactor for plastic conversion [83]. (Reproduced by permission of Javier Bilbao)... 

The cracking of PE/LCO and PP/LCO blends over HZSM-5 zeolite catalysts in the riser simulator at 450°C led towards mainly a C5-C12 hydrocarbon fraction of aromatic nature and a low yield of C1-C2 gases and coke. 

Arandes et al. [84] studied the catalytic degradation of several plastics (polypropylene, polystyrene, polystyrene-polybutadiene) dissolved in a light cycle oil (ECO) in a riser simulator of a ECC unit using both a fresh and an equilibrated ECC catalysts. Similarly, De la Puente [85, 112] studied the catalytic degradation of styrene-based polymers dissolved in benzene streams in the same riser simulator. Although the reported results are promising, oil refiners are reluctant regarding the inherent risks for the normal operation of the refinery units. 

G. de la Puente et al. [48] LDPE Riser simulator reactor 6.5 EquiUbrium Engelhard FCC catalyst ASA... 

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. 

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