FCC Issues

Startup & Shutdown

EPA Offices - RTP

May 22, 2012

The following slides were presented by 

Jeff Sexton of Marathon, based on 

data obtained from member 

companies of the FCCU Technical 

Consenters Team and presented 

during an API meeting with EPA.
2

FCC Startup & Shutdown Discussion Topics

Backend Control Technology Overview

Technical Concerns & Issues During Startup & Shutdown

Torch Oil Process Design & Utilization

Case Studies – FCC Startup & Shutdown Emissions

FCC Startup & Shutdown Process Dynamics

Advocacy Recommendation
3

FCC Emission Control Technology Options

FCC Regenerator

Expander

WH/CO Boiler

4th

stage

(FSS)

TSS SCR

Wet Gas

Scrubber

LoTOx

Scrubber

SNCR

Torch Oil

ESP

DFAH

Sketch shows most types of FCC flue gas emission 

control technology options. Technology selection is 

unit specific. A particular FCC would not use all of 

these technologies.
4

Technical Concerns & Issues – Startup & Shutdown

 Provisions for Torch Oil Use

 Increased CO Emissions

 Provisions for Start-Up Of CO Boiler

 Increased CO Emissions During Boiler Commissioning

 Provisions for Start-Up Of SCR Unit

 Increased NOx While Commissioning SCR and Increasing Temperature

 Bypass During Unit Start-Up to Minimize Catalyst Accumulation

 Provision for Start-Up of LoTOx Unit

 Need Sulfites to Absorb Excess Ozone (only after feed-in)

 Provisions for Start-Up Of ESP Unit

 Do Not Energize Until After Stable Operation Based Upon Safety

 Increased PM Emissions Until ESP Is Energized

 Provisions Transitory Operations (Hot Standby)

 Prolonged use of torch oil to minimize temperature cycles and start-up time

 NOTE: Hot Standby can result either from an unplanned shutdown, or from a planned shutdown of 

limited time duration. Either scenario provides data that illustrates the effects of torch oil on CO 

emissions since it is the use of torch oil (and not the reason for shutdown) that increase CO emissions. 
5

FCC Startup & Shutdown Discussion Topics

Backend Control Technology Overview

Technical Concerns & Issues During Startup & Shutdown

Torch Oil Process Design & Utilization

Case Studies – FCC Startup & Shutdown Emissions

FCC Startup & Shutdown Process Dynamics

Advocacy Recommendation
6

Torch Oil Process Design

Retractable Nozzle

FEED STEAM
7

Torch Oil Design

Torch Oil Distribution

Typically 1-5 distribution points

Used in Conjunction with DFAH 

– gas burner
8

Torch Oil Distribution
9

FCC Startup & Shutdown Discussion Topics

Backend Control Technology Overview

Technical Concerns & Issues During Startup & Shutdown

Torch Oil Process Design & Utilization

Case Studies – FCC Startup & Shutdown Emissions

FCC Startup & Shutdown Process Dynamics

Advocacy Recommendation
10

Case Study – FCC Unit Trip & Restart (Unit A2 with Baghouse)

% ppm ppm ppm %

fb:ai24c fb:ai25c fb:ai26c fb:ai23c fb:ai27c

O2 CO NOx SO2 PM

2/5/2012 15:00 2.224893 0.041363 14.37988 12.17822 4.220494

2/5/2012 16:00 9.815133 646.0181 4.611854 7.822043 4.076272

2/5/2012 17:00 10 1000 2.463162 4.532601 4.393805

2/5/2012 18:00 10 1000 1.663704 7.346815 4.315623

2/5/2012 19:00 10 1000 0.525491 9.9804 4.427371

2/5/2012 20:00 10 1000 1.268489 6.878176 4.363206

2/5/2012 21:00 10 1000 2.240567 6.583831 4.641382

2/5/2012 22:00 10 1000 2.319089 6.083542 4.73274

2/5/2012 23:00 10 1000 4.374256 5.38329 5.282178

2/6/2012 0:00 10 1000 1.277679 2.760265 5.189806

2/6/2012 1:00 10 990.8149 32.74268 -1.12886 6.451317

2/6/2012 2:00 10 612.9687 38.50444 1.17072 6.745082

2/6/2012 3:00 10 282.9718 42.66721 3.526949 6.402687

2/6/2012 4:00 9.625029 248.479 44.20884 4.237224 6.244692

2/6/2012 5:00 6.305254 175.9361 46.05983 4.068154 5.561254

2/6/2012 6:00 3.440695 18.86569 31.3849 1.040237 5.103787

2/6/2012 7:00 2.340538 28.34961 23.29546 2.139952 4.801994

2/6/2012 8:00

2/6/2012 9:00

Unit Trip

(loss of instrument air)

Feed-In

Example of Unit Trip and Restart – This particular case was caused by loss of

Instrument air causing a Safety Instrumented System to activate. The 

operator responded by introducing torch oil to maintain regenerator

temperatures and was able to re-introduce feed ~10 hours later. Duration of

restart will depend on many factors. . CO emissions remained high during the restart 

period (at CEMS maximum span) due to use of torch oil.The high resultant CO is from 

torch oil usage and would be the same for either a planned or unplanned shutdown
11

Case Study – FCC Unit Start-Up After TAR

(Unit A4 with FGS)

O2 CO NOx SOx

3/14/2012 0:00 10.01 34.73 0.47 0.25

3/14/2012 1:00 10.01 67.35 0.56 0.25

3/14/2012 2:00 10.01 175.26 2.71 0.25

3/14/2012 3:00 10.01 374.89 0.67 0.25

3/14/2012 4:00 10.01 318.17 0.47 0.25

3/14/2012 5:00 8.71 298.89 0.47 2.43

3/14/2012 6:00 6.26 268.93 0.48 14.81

3/14/2012 7:00 10.01 630.74 1.22 0.25

3/14/2012 8:00 10.01 1027.66 0.69 0.25

3/14/2012 9:00 10.01 1027.66 0.48 0.25

3/14/2012 10:00 10.01 1027.66 0.47 0.25

3/14/2012 11:00 10.01 1027.66 0.46 0.25

3/14/2012 12:00 10.01 1027.66 0.47 0.76

3/14/2012 13:00 10.01 1027.66 0.47 17.56

3/14/2012 14:00 10.01 888.85 0.47 33.19

3/14/2012 15:00 10.01 973.17 0.53 56.76

3/14/2012 16:00 10.01 286.34 4.09 72.43

3/14/2012 17:00 10.01 1027.39 0.47 62.10

3/14/2012 18:00 10.01 1028.08 0.48 64.21

3/14/2012 19:00 8.44 860.67 22.08 87.50

3/14/2012 20:00 2.18 118.21 54.32 195.33

3/14/2012 21:00 2.38 172.64 54.50 22.34

3/14/2012 22:00 1.48 60.97 47.73 7.33

3/14/2012 23:00 1.30 41.13 42.38 14.75

3/15/2012 0:00 1.33 32.10 40.86 5.00

3/15/2012 1:00 1.39 33.89 40.94 0.67

3/15/2012 2:00 1.09 40.38 32.79 0.25

Feed-In

Example of Unit Restart After TAR –This data shows emissions during a

unit restart after a maintenance turnaround. Duration of restart will depend

on many factors. CO emissions remained high during the restart period (at CEMS maximum

span) due to use of torch oil. Again this illustrates that any feed out condition of the FCCU

(whether planned or unplanned) which necessitates the use of torch oil to either maintain

or reheat the regenerator bed temperatures will have increased CO emissions.

SEE CLJ 

BOLDED 

COMMENT 

ADDED 

BELOW
12

Case Study – FCC Unit Trip & Restart (Unit A3 with ESP)

o2 CO Nox SO2 Opacity Torch Oil

% PPM PPM PPM % BPD

10/15/2010 8:00 2.95 92 107 6 6.47 0

10/15/2010 9:00 2.82 86 106 6 6.28 0

10/15/2010 10:00 2.79 77 105 6 6.13 0

10/15/2010 11:00 2.72 77 104 6 5.88 0

10/15/2010 12:00 3.55 175 107 5 6.34 0

10/15/2010 13:00 6.41 356 55 2 17.64 0

10/15/2010 14:00 10.00 219 9 3 14.73 52.12

10/15/2010 15:00 10.00 822 26 7 19.20 96.10

10/15/2010 16:00 10.00 1000 35 11 22.55 98.55

10/15/2010 17:00 10.00 1000 48 15 14.95 83.67

10/15/2010 18:00 10.00 1000 34 11 14.87 66.60

10/15/2010 19:00 10.00 113 11 5 10.18 9.93

10/15/2010 20:00 10.00 9 6 3 3.97 7.85

11/18/2010 9:00 10.00 1000 26 22 14.41 183.50

11/18/2010 10:00 10.00 915 21 24 12.98 159.67

11/18/2010 11:00 3.17 445 28 34 14.46 174.65

11/18/2010 12:00 3.68 222 91 77 17.53 128.03

11/18/2010 13:00 4.59 323 103 7 18.34 72.15

11/18/2010 14:00 3.21 42 107 18 17.96 181.85

11/18/2010 15:00 4.61 180 114 14 21.33 111.31

11/18/2010 16:00 5.12 601 114 1 21.54 0

11/18/2010 17:00 4.31 648 117 2 12.69 0

11/18/2010 18:00 3.84 511 116 3 3.72 0

11/18/2010 19:00 3.94 683 114 3 3.68 0

11/18/2010 20:00 2.96 258 109 5 2.78 0

11/18/2010 21:00 3.96 577 104 3 3.25 0

Unit Trip

Feed-In

Example of Unit Trip and Restart – This particular case was caused by loss of

power causing a Safety Instrumented System to activate. The operator 

responded by introducing torch oil to maintain regenerator

temperatures and was able to re-introduce feed ~10 hours later. Duration of

restart will depend on many factors. CO emissions remained high during the 

restart period (at CEMS maximum span)due to use of torch oil. The high resultant CO is 

from torch oil usage and would be the same for either a planned or unplanned shutdown.

SEE CLJ 

BOLDED 

COMMENT 

ADDED 

BELOW
13

Case Study – FCC Unit Trip & Restart (Unit A1 with TSS)

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CO (ppm); SOx (ppm)

NOx (ppm); Opacity (%); O2 (%)

NOx Opacity O2 CO SOx Shutdown 10/1 10:45 PM Start Up 10/4 12:12 AM

Example of Unit Trip and Restart – This particular case was caused by a unit

upset causing a Safety Instrumented System to activate. The 

operator responded by introducing torch oil to maintain regenerator

temperatures and was able to re-introduce feed ~61 hours later. Duration of

restart will depend on many factors. In this example, other equipment problems

Delayed feed-in. CO emissions remained high during the restart period (at CEMS maximum span)

due to use of torch oil. The high resultant CO is from torch oil usage and would be the same 

for either a planned or unplanned shutdown.

SEE CLJ BOLDED COMMENT 

ADDED
14

Case Study – FCC Unit Trip & Restart (Unit A1 with TSS)

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CO (ppm); SOx (ppm)

NOx (ppm); Opacity (%); O2 (%)

NOx O2 Opacity CO SOx Shutdown 12/11 10:30 AM Start Up 12/15 1:30 PM

Example of Unit Trip and Restart – Same example as previous case study.

Only exception is opacity spiked during this restart. A technician reported

the opacity meter beam was not aligned with its receiver due to thermal

expansion. Ambient temperature was very cold. CO emissions remained high 

during the restart period due to use of torch oil. Restart took 99 hours.
15

Case Study – FCC Unit Trip & Restart (Unit A6 with LoTox + FGS)

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CO (ppm); SOx (ppm)

NOx (ppm); Opacity (%); O2 (%)

NOx Opacity O2 CO SOx ESD @3:39 Feed in @ 21:30

Example of Unit Trip and Restart – This particular case took 18 hours to restart.

LoTOx was not operational during this period to minimize ozone slip without

Any sulfites in scrubber liquor. CO emissions remained high during the 

restart period due to use of torch oil.
16

Case Study – FCC Unit Trip & Restart (Unit A5 with COB+FGS+SNCR)

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CO (ppm); SOx (ppm)

NOx (ppm); Opacity (%); O2 (%)

NOx Opacity O2 CO SOx Unit Shutdown Feed In

Example of Unit Trip and Restart – This particular case took 9 hours to restart.

CO emissions were controlled with use of torch oil since this unit had a CO Boiler 

and was able to maintain operation during restart. Not all CO Boilers are 

maintained on-line during restart due to safety concerns.
17

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CO (ppm); SOx (ppm)

NOx (ppm); Opacity (%); O2 (%)

NOx Opacity O2 CO SOx Unit Shutdown

Case Study – FCC Unit Shutdown (Unit A5 with COB+FGS+SNCR)

Example of Unit Shutdown – CO emissions were controlled with a CO Boiler. 

Not all CO Boilers are maintained on-line during shutdown due to safety concerns.
18

Case Study – FCC Unit Shutdown (Unit B1 with TSS+PRU+ESP)

Example of Unit Shutdown – CO emissions 

collected with temporary analyzer with higher span 

than CEMS to collect higher CO values during 

shutdown. Note CEMS is at maximum span of 

1000ppm but actual CO emissions were above 

3000ppm as a result of the need to use of torch oil 

to maintain regenerator bed temperature
19

Case Study – FCC Unit Shutdown (Unit B1 with TSS+PRU+ESP)

Example of Unit Shutdown – Same unit as previous slide. Data shows other emissions.
20

Case Study – FCC Unit Startup (Unit B1 with TSS+PRU+ESP)

Example of Unit Startup– CO emissions collected with 

temporary analyzer with higher span than CEMS to 

collect higher CO values during startup. Note CEMS is at 

maximum span of 1000ppm, and CO emissions from 

analyzer hit the maximum span of 5000ppm as a result 

of the need to use of torch oil to heat up the regenerator 

bed temperature prior to feed introduction
21

Case Study – FCC Unit Startup (Unit B1 with TSS+PRU+ESP)

Example of Unit Startup – Same unit as previous slide. Data shows other emissions.
22

Case Study – FCC Unit Startup From Hot Standby (Unit B1)

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2/2/12 12:00 2/3/12 0:00 2/3/12 12:00 2/4/12 0:00 2/4/12 12:00

CO Emissions

(ppm) 

Feed (MBPD) 

Torch Oil (BPH) FCU Hot Standby - CO emissions

Total FCU Feed (MBPD) Torch Oil SE Nozzle (bph) CO Rolling 1hr Average (ppm)

Example of Unit Startup –CO emissions 

were high (at CEMS maximum span) due 

to use of torch oil to maintain regenerator 

bed temperatures prior to feed

Introduction. The high resultant CO is 

from torch oil usage and would be the 

same for either a planned or unplanned 

shutdown
23

Case Study – FCC Unit Startup 

(Unit C1 with ESP-prior to 2010 and FGS post 2010)

Startup Jan 2010 May 2009 Sep 2008 Nov 2007

60 Day Period After Startup

Stack NOx, ppmvd

 Period Average 111 101 84 65

 Maximum Daily 253 154 171 159

Stack CO, ppmvd (1)

 Period Average 21 38 36 32

 Maximum Daily 255 572 717 541

Regenerator Flue Gas CO, ppmvd

 Period Average 60 80 54 69

 Maximum Daily 585 1812 1898 1319

Low-NOx Promoter Injection

 Period Average, lb/day 59 45 41 32

 Cumulative Total, lb 3511 2701 2435 1898

96 Hour Period After Startup

Stack NOx, ppmvd

 Period Average 137 93 117 53

 Maximum Hourly 298 198 222 298

Stack CO, ppmvd (1)

 Period Average 98 208 207 164

 Maximum Hourly 1000 1000 1000 1000

Regenerator Flue Gas CO, ppmvd

 Period Average 243 576 494 561

 Maximum Hourly 5901 5381 4693 9503

Notes

(1) Stack CO CEMS maximum range = 1000 ppmvd

Example of Unit Startup –

CO emissions collected with 

temporary CEM to collect 

higher CO values during 

startup. CO emissions were

high due to use of torch oil. 

Note that the hourly 

averages (red circle below) 

are at maximum span of 

1000ppm for the CO CEMS, 

but the analyzer shows values 

in the 4500 – 9500 ppm range 

for a span of 10,000ppm. 
24

0

2000

4000

6000

8000

10000

0 8 16 24 32 40 48 56 64 72 80 88 96

Regen Flue Gas CO, ppmvd

Hour

FCC Startups - Regenerator Flue Gas CO

Hourly Average Data

Jan 2010 May 2009 Sep 2008 Nov 2007

Case Study – FCC Unit Startup 

(Unit C1 with ESP-prior to 2010 and FGS post 2010)

Example of Unit Startup –

CO emissions collected from 4 

different unit start-ups to show 

range and variability. A 

temporary CEM was used to 

collect higher CO values. CO 

emissions were high due to use 

of torch oil.
25

Case Study – FCC Unit Startup (Unit C2 with COB + ESNCR + FGS)

0

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0 20 40 60 80 100 120 140

Stack CO, ppmvd

Hour Reference

FCC Startup - Apr12

Stack CO - Hour Average Data

Exceeded 500 ppm CO

With COB in Operation

Example of Unit Startup –

CO emissions, even with at 

fired COB in service, can 

exceed 500ppm on startup. 

Additionally, not all FCCU’s will 

start-up with a COB in service 

due to safety and plant 

stability concerns
26

FCC Startup & Shutdown Discussion Topics

Backend Control Technology Overview

Technical Concerns & Issues During Startup & Shutdown

Torch Oil Process Design & Utilization

Case Studies – FCC Startup & Shutdown Emissions

FCC Startup & Shutdown Process Dynamics

Advocacy Recommendation
27

FCC Startup = Process Dynamics

Drawing Removed Since Did Not Get Permission From Licensor
28

FCC Startup & Shutdown Discussion Topics

Backend Control Technology Overview

Technical Concerns & Issues During Startup & Shutdown

Torch Oil Process Design & Utilization

Case Studies – FCC Startup & Shutdown Emissions

FCC Startup & Shutdown Process Dynamics

Advocacy Recommendation
29

Advocacy Recommendations – Work Practice Standards

 Safety and operability risks for running some flue gas emission control 

equipment (such as ESP, SCR and SNCR) during FCC startup

 FCC Startup & Shutdown Emissions Are Not Practical to Measure 

 FCC startups and shutdowns are generally infrequent – contribution to 

long-term pollutant mass emissions is relative small

 Typical refinery goal is a 4-5 year FCC run length 

 PM Testing During S/U Represents Safety Risk & No Coke Burn

 The EPA should consider a technology-based exemption to any shortterm limits during transitory periods associated with startup, 

shutdown, and hot standby operations. The EPA could accomplish this 

by requiring facilities to prepare a Startup/Shutdown Plan, outlining 

the specific steps to be taken to minimize FCCU emissions during this 

period. The long-term limits would still need to be met.