H.J.Pant1, P.Brisset2, Ph.Berne3, G.Gousseau3,

A.Fromentin3

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

ID: B09-04

Radiotracer Investigations in an

Industrial-scale Fluid Catalytic Cracking Unit

(FCCU)

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 micro-

spherical zeolitic catalyst which

fluidizes when it comes in

contact with heated crude oil

resulting in conversion high-

boiling 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.

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.

Why Radiotracer Investigations?

Radiotracer Investigations

Riser reactor

Disengager

Stripper

Regenerator

Test No.

Section

(Sub-system)

Phase Tracer Activity used

Det. points

1. Riser Catalyst La-140 60 mCi 15

2. Riser Catalyst La-140 50 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

13

6. Stripper (S) Catalyst La-140 40 mCi 13

7. Stripper (N) Catalyst La-140 40 mCi 13

8. Regenerator Gas Kr-79 115 mCi 10

9. Regenerator Catalyst La-140 10 mCi 10

10. Regenerator Catalyst La-140 20 mCi 10

Krypton-79,

Half-life: 36 hrs, Gamma energy: 0.52 Mev

Lantanum-140 as irradiated catalyst

(Half-life: 40 hrs, Gamma energies: : 0.92 Mev, 2.54 Mev)

Radiotracer Injection and Monitoring

To fractionator

Riser

D11, D6, D3

E

a. Detector orientation for riser

La-140 injection for regenerator

Kr-79 and La-140 injection for riser and reactor

D7a, D3a

D12a, D7a

D12, D5, D2

D13, D7, D4

c. Detector orientation for regenerator

Flue gas

N

Kr-79 injection for regenerator

Disengager

D10

D8a D9a

D8 D9

D11 D12

D14

D13

D5 D6

D2 D3 D2

D1

Stripper

Regenerator

Standpipes

D8b D7a

D3a

D2a D13a D11a D12a

D10a

D5a

D9b

D15 Combustion air

Feed (Heavy oils)

D7

S

b. Detector orientation for disengager

N

E W

D8a D8

D9 D9a

S

E W

N

D13a, D8b

D11a, D6a

S

W

Kr-79 and La-140 injection for stripper

-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

0 20 40 60 80 100 120 140 160 180 200

Co

un

ts/1

00 m

s

Time (s)

Fig. CR2 Untreated solid tracer distribution curves

D16 D2

D3 D4

D5 D6

D7 D8

D9 D10

D11 D12

D13 D14

D15Peak due to washing of injection system

Typical Radiotracer Curves (Solid Phase)

Results: Radial Distribution

10 15 20 25 30-1000

0

1000

2000

3000

4000

5000

6000

7000(a)-Riser-reactor

Concentr

ation (

Counts

/100 m

illis

econd)

Time (Second)

D2

D3

D4

D5

D6

D7

24 26 28 300

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

(a)-Riser-reactor

Co

un

ts/2

0 m

illis

eco

nd

Time (Second)

D2

D3

D4

D5

D6

D7

Riser reactor: Solid phase (Good)

Riser reactor: Gas phase (Good)

0 5 10 15 20 25 30 35 400

100

200

300

400

500

600

700

800

Regenerator

Concentr

ation (

Counts

/20 m

illis

econd)

Time (Second)

Level 1-D3

Level 1-D6

Level 1-D7

Level 1-D8

Level 2-D2

Level 2-D11

Level 2-D12

Level 2-D13

Regenerator: Gas phase (Poor)

0 20 40 60 80 100 120 140 1600

2000

4000

6000

8000

10000 (c)-Stripper

Co

nce

ntr

atio

n (

Se

co

nd

)

Time (Second)

D11

D12

D13

Stripper: Solid phase (Good)

30 35 40 45 500

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

(b)-Stripper top

Radio

tracer

concentr

ation (

Counts

/20 m

illis

econd)

Time (s)

D11

D12

D13

Stripper: Gas phase (Poor)

10 20 30 40 50 60 70 800

1000

2000

3000

4000

5000

6000

(b)-Disengeger

Co

nce

ntr

atio

n (

Co

un

ts/2

0 m

illis

eco

nd

)Time (Second)

D8

D9

0 20 40 60 80 100 120 140-500

0

500

1000

1500

2000

2500

3000(b)-Disengager

Concentr

ation/1

00 m

illisecond

Time (Second)

D8

D9

Disengager: Gas phase (Poor)

Disengager: Catalyst (Poor)

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 10.6

Slip factor= Velocity of gas phase/velocity of solid phase=1.6

Solid t phase Gas phase

Detectors τ Pe Detectors τ Pe

D3 – D6 2.1 7.4 D3 – D6 1.44 61

Axial dispersion (Riser)

Results of Model Simulations (ADM)

0 10 20 30 40 50-0.02

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

No

rma

lize

d c

on

ce

ntr

ati

on

, E

(t)

(1/s

)

Time (s)

Experimental (D13)

ADP Model simulated

( s, P=17.3)

Solid phase in riser

Gas phase in regenerator

Gas phase in riser

0 5 10 15 20 250.00

0.05

0.10

0.15

0.20

0.25

0.30N

orm

ali

se

d t

rac

er

co

nc

en

tra

tio

n (

s-1)

Time (s)

Mean of D2, D3, D4

Mean of D5, D6, D7

ADM Simulated

MRT: 2.1 s, Pe: 8

Experimetal MRT: 2.4 s

24 26 28 300.0

0.5

1.0

1.5

2.0Experimetal MRT: 1.47 s

Mean of D2, D3, D4

Mean of D5, D6, D7

ADM Simulated

MRT: 1.41 s, Pe: 84

Time (s)

No

rma

lis

ed

tra

ce

r c

on

ce

ntr

ati

on

(s

-1)

0 10 20 300.00

0.05

0.10

0.15

0.20

0.25

E(t

)(s

-1)

Time (s)

Experimental

Model

Gas phase in Stripper

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.