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
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.
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.
Radiotracer Investigations Regenerator Disengager Stripper Test No. Section (Sub-system) Phase Tracer Activity used Det. points 1. Riser Catalyst La-14 6 mci 15 2. Riser Catalyst La-14 5 mci 15 3. Riser Gas Kr-79 213 mci 15 4. Stripper (N) Gas Kr-79 192 mci 13 5. Stripper (S) Gas Kr-79 188 mci 6. Stripper (S) Catalyst La-14 4 mci 13 13 Riser reactor 7. Stripper (N) Catalyst La-14 4 mci 13 8. Regenerator Gas Kr-79 115 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)
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
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 D12 6 4 Peak due to washing of injection system D13 D15 D14 2 2 4 6 8 1 12 14 16 18 2-2
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) 7 6 5 4 3 2 1 (a)-riser-reactor -1 1 15 2 25 3 D2 D3 D4 D5 D6 D7 Riser reactor: Gas phase (Good) 1 (c)-stripper 8 6 4 2 2 4 6 8 1 12 14 16 D11 D12 D13 Stripper: Gas phase (Poor) 8 7 6 5 4 3 2 1 Regenerator 5 1 15 2 25 3 35 4 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) 3 25 2 (b)-disengager D8 D9 2 18 16 14 12 1 8 6 4 2 (a)-riser-reactor 24 26 28 3 D2 D3 D4 D5 D6 D7 2 18 16 14 12 1 8 6 4 2 (b)-stripper top 3 35 4 45 5 D11 D12 D13 15 1 5-5 2 4 6 8 1 12 14 Disengager: 6 Gas phase (Poor) 5 4 3 2 1 (b)-disengeger D8 D9 1 2 3 4 5 6 7 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) 15.87 2.4 6.6 Gas phase D(2,3,4)-D(5,6,7) 15.87 1.5 1.6 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 D6 2.1 7.4 D3 D6 1.44 61
Normalized concentration, E(t) (1/s) Normalised tracer concentration (s -1 ) Normalised tracer concentration (s -1 ) Results of Model Simulations (ADM).3.25.2.15.1 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: 84 1..5. 5 1 15 2 25.14.12.1.8.6.4.2. -.2 Gas phase in regenerator Experimental (D13) ADP Model simulated ( s, P=17.3) 1 2 3 4 5.5. 24 26 28 3 E(t)(s -1 ).25.2.15.1.5 Gas phase in Stripper Experimental Model. 1 2 3
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.