Radiotracer Investigations in an Industrial-scale Fluid Catalytic Cracking Unit (FCCU)

Transcription

1 ID: B9-4 Radiotracer Investigations in an Industrial-scale Fluid Catalytic Cracking Unit (FCCU) H.J.Pant 1, P.Brisset 2, Ph.Berne 3, G.Gousseau 3, A.Fromentin 3 1: Isotope and Radiation Application Division, Bhabha Atomic Research Centre Mumbai, India 2: International Atomic Energy Agency, Vienna, Austria 3: DTEN/SAT-CEA Grenoble, Cedex, France

2 Fluid Catalytic Cracking Fluidized Catalytic Cracking is a process used in petroleum refining for production of petrol, diesel, naphtha, ATF and LPG. The process utilizes a microspherical zeolitic catalyst which fluidizes when it comes in contact with heated crude oil resulting in conversion highboiling petroleum fractions to more useful products. The process is carried out in a unit called Fluid Catalytic Cracking Units (FCCU), consisting of four sub-systems named as riser reactor, stripper, disengager and regenerator.

3 Why Radiotracer Investigations? The efficiency and quality of the products produced in a FCCU depends upon flow parameters such as residence times, velocities, slip factor, axial and radial mixing of the flowing phases. A radiotracer investigation was carried in an industrial FCCU in a refinery in INDIA to measure the various flow parameters before revamping, stepping up the production and modification of design of some of the components.

4 Radiotracer Investigations Regenerator Disengager Stripper Test No. Section (Sub-system) Phase Tracer Activity used Det. points 1. Riser Catalyst La-14 6 mci Riser Catalyst La-14 5 mci Riser Gas Kr mci Stripper (N) Gas Kr mci Stripper (S) Gas Kr mci 6. Stripper (S) Catalyst La-14 4 mci Riser reactor 7. Stripper (N) Catalyst La-14 4 mci Regenerator Gas Kr mci 1 9. Regenerator Catalyst La-14 1 mci 1 1. Regenerator Catalyst La-14 2 mci 1 Krypton-79, Half-life: 36 hrs, Gamma energy:.52 Mev Lantanum-14 as irradiated catalyst (Half-life: 4 hrs, Gamma energies: :.92 Mev, 2.54 Mev)

5 Radiotracer Injection and Monitoring D8a D1a Stripper La-14 injection for regenerator D2a D13a D11a D12a D8b W D9 Regenerator D9b N D8a D8 S b. Detector orientation for disengager Flue gas D7a D9a E D3a D14 D8 Standpipes D11 D5 Disengager D12 D6 D1 D7 D13 Riser To fractionator D9a D9 Kr-79 and La-14 injection for stripper D5a Kr-79 injection for regenerator Combustion air D15 D2 D3 D2 D1 Kr-79 and La-14 injection for riser and reactor Feed (Heavy oils) N D11a, D12a, D7a D6a W E D13a, D8b D7a, D3a S c. Detector orientation for regenerator D13, D7, D4 W D11, D6, D3 E D12, D5, D2 S a. Detector orientation for riser N

6 Counts/1 ms Typical Radiotracer Fig. CR2 Untreated solid Curves tracer distribution curves (Solid Phase) 16 D16 D2 14 D3 D4 12 D5 D6 1 D7 D9 D8 D1 8 D11 D Peak due to washing of injection system D13 D15 D

7 Counts/2 millisecond Radiotracer concentration (Counts/2 millisecond) Concentration (Counts/2 millisecond) Concentration/1 millisecond Concentration (Counts/1 millisecond) Concentration (Second) Concentration (Counts/2 millisecond) Results: Radial Distribution Riser reactor: Solid phase (Good) Stripper: Solid phase (Good) Regenerator: Gas phase (Poor) (a)-riser-reactor D2 D3 D4 D5 D6 D7 Riser reactor: Gas phase (Good) 1 (c)-stripper D11 D12 D13 Stripper: Gas phase (Poor) Regenerator Level 1-D3 Level 1-D6 Level 1-D7 Level 1-D8 Level 2-D2 Level 2-D11 Level 2-D12 Level 2-D13 Disengager: Catalyst (Poor) (b)-disengager D8 D (a)-riser-reactor D2 D3 D4 D5 D6 D (b)-stripper top D11 D12 D Disengager: 6 Gas phase (Poor) (b)-disengeger D8 D

8 Results (Riser): MRT, velocities, Slip factor Detector Nos. Table Distance (m) MRT(s) Velocity (m/s) Solid phase D(2,3,4)-D(5,6,7) Gas phase D(2,3,4)-D(5,6,7) Slip factor= Velocity of gas phase/velocity of solid phase=1.6 Axial dispersion (Riser) Solid t phase Gas phase Detectors τ Pe Detectors τ Pe D3 D D3 D

9 Normalized concentration, E(t) (1/s) Normalised tracer concentration (s -1 ) Normalised tracer concentration (s -1 ) Results of Model Simulations (ADM) Solid phase in riser Experimetal MRT: 2.4 s Mean of D2, D3, D4 Mean of D5, D6, D7 ADM Simulated MRT: 2.1 s, Pe: 8 Gas phase in riser 2. Experimetal MRT: 1.47 s Mean of D2, D3, D4 Mean of D5, D6, D7 1.5 ADM Simulated MRT: 1.41 s, Pe: Gas phase in regenerator Experimental (D13) ADP Model simulated ( s, P=17.3) E(t)(s -1 ) Gas phase in Stripper Experimental Model

10 Conclusions Radiotracer investigations were successfully carried out to measure flow parameters in an industrial-scale FCCU. The results of the investigation were utilized for process intensification, design modification and process optimization.

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