International Society for Industrial Process Tomography

Identification and Digital Control Design for a Pilot FCC
Type Unit using Gamma Transmission Measurements

Antônio J. Cruz F.º ¹* , Enivaldo S. Barbosa¹ , Carlos C. Dantas¹ , Hilário J. B. de

Lima F.º ² , Emerson A. O. Lima⁴ , Silvio B. Melo⁵

¹Universidade Federal de Pernambuco – DEN/UFPE, Recife, PE, Brazil.

²Universidade Católica de Pernambuco – UNICAP, Recife, Pernambuco, Brasil.

³Universidade de Pernambuco – UPE, Recife - PE, Brasil.

⁴Universidade Federal de Pernambuco – CIN/UFPE, Recife, PE, Brazil.

^*Email: antoniocruzfh@unicap.br / antonio.jcf@gmail.com

ABSTRACT

A digital control design of a CFB - Circulating Fluidized Bed pilot cold unit is proposed using pressure and catalyst concentration as process variables. Circulating two-phase flow FCC – Fluid Catalyst Cracking type unit fluid dynamic is under study aiming the scale-up process to industrial scale. Flow investigation by means of gamma ray tomography evaluates fluid dynamic parameters in a non-intrusive methodology. Such a contribution in a literature review shows that solid transport in dense phase, circulating inside unit geometry according to steady state conditions as required for mathematical models, are still a challenge for control technology. The studies were carried out simulating a transfer function by dynamical system identification using concentration as function of solid flow rate. The model obtained by system identification is validated and the results compared with experimental data. A digital controller is projected and analysed in a closed-loop feedback system and built in Matlab/Simulink functions. The output signals were modified by regular pulses and regular noise and a control function is tuned by computing technique. Independent variables are pressure, air flow and gamma intensity by which the fluid parameters are determined. Simulations of the identified system response under digital controller action show the effectiveness of this approach.

Keywords two-phase flow, gamma ray measurements, digital control, system identification

Industrial Application chemical industry, oil industry.