100% AFR and high S petcoke with 500

mg/Nm3 NOx without SNCR

by The CINAR TEAM

Presented by Tom Lowes

at Cemtech Conference Marrakech 12th Feb 2013

Summary

Experience based fundamental practical rules to achieve 100% AFR with a

high S petcoke are outlined; together Plant Cases where it has been done,

with the use of Process Knowledge and experience aided as needed by MI-

CFD, together with the basics of low CAPEX hot reburn retrofits to drop the

contribution of kiln NOx and calciner fuels N to NOx emissions with Plants

cases where it has been done to meet < 500 mg/Nm3 without SNCR

100% AFR and high S petcoke with 500

mg/Nm3 NOx without SNCR

Not easy to achieve

Outside experience of most process people

Need to Understand ( 3W’s):

Why there is a the Problem?

Where is it occurring ?

WHTBD?

Have the ability to go in side the kiln and calciner and see WHERE the

problem is happening and WHY.

Then Identify WHTBD via Process Knowledge, MI-CFD simulations

and interpretation of a range of potential solutions

This paper will give the rules and show how it can be done for little or no

additional CAPEX on 5 of the 130 + Plants Projects that have been done by

the CINAR TEAM as a means of guiding Plants to their own specific

solutions

100% AFR and high S petcoke with 500

mg/Nm3 NOx without SNCR

Needs

Avoid excessive build up

No Significant loss of output

No increased VOC emission

Hit NOx targets

Rules for AFR and Petcoke

VF < 2

HM Carbon < 0.1%

HM Cl < 1%

Eliminate Kiln and Calciner Stratification

Need MOT not 3T’s

M – Micro mixing

O – Oxygen

T – Temperature

Additional for 500 mg/Nm3

MOT ++

i.e. Volatiles and sub stoichiometric RT

Combustion in a

very narrow

region

Case I

An AT Calciner 100% < 5% S petcoke

plus 15% Tyre Shreds

Stopping to dig put the Kiln and Riser

Every 3 weeks

0

0.2

0.4

0.6

0.8

1

1.2

1.4

2 2.5 3 3.5 4 4.5 5 5.5 6

Clin

ke

r %

SO

3

%O2

Clinker SO3 vs Preheater O2

Calculated Clinker SO3 lelvel So excess HOLDING up in riser and needing stops for digging out

WHY?

VF SO3 13.5

HMSO3 6.0

CO ppm 4856.3

O2 % 4.9

NOx ppm 248.0

tdf TSR 15

Average

O2 too low need @ 3.5% for petcoke plus tdf a top of riser - @ 6 at

PH and burner mmtm too low at 4 N/MW need 9 N/MW

CO at @ 5000 ppm

indicative of

Volatiles of tdf not

micro mixing with O2

before quenching.

NOx < 500 mg/Nm3

at 10% O2

MI - CFD Application to Kiln

O2

stratification

due to too

low a

momentum

MI - CFD Application to Kiln

Petcoke Combustion- 5 N/MW

Particle Size: 10 µm

Particle Size: 22 µm

Particle Size: 35 µm

Particle Size: 45 µm

Particle Size: 90 µm

Compare the +45 &

90u burnout on this

slide compared to

next one

MI - CFD Application to Kiln - Increased mmtm

Petcoke Combustion – 10 N/MW

Particle Size: 10 µm

Particle Size: 22 µm

Particle Size: 35 µm

Particle Size: 45 µm

Particle Size: 90 µm

Hence the

appropriate mmtm

can overcome +90u

issues

Plant feedback SO3 vs O2

R2 = 0,8157

0

1

2

3

4

5

6

5 5,5 6 6,5 7 7,5

O2

SO

3

SO3 VS O2 Polynomial (SO3 VS O2)

initial present Burner mmtm (N/MW) 4,30 7,10 SO3 (average ) 6,02 2,91 SO3 sd 2,47 0,89 SO3 (average) 0,53 0,95 SO3 sd 0,26 0,15 VF ( average) 13,48 3,21 Nox (average) 226 467 CO preheater 0,51 0,14

clinker

Hot meal

Combustion

Average PH O2

@ 6%

No stoppage for

digging out and build

up

So can go for 7% S

BUT disaster struck

Plant personnel

changed and lessons

learnt forgotten and

strive for low O2 and

thinking more output

0

2

4

6

8

10

12

0.78 0.98 1.18 1.38 1.58 1.78 1.98 2.18

Nu

mb

er

of

sa

mp

les

% SO3 in Clinker

High S Petcoke Trial

Target 1.9% SO3 in clinker to avoid build up

Lessons Learnt were forgotten too low PH O2 used on the misconception

more output would be achieved – ran 10 days and then had to shut down to

dig out the build up

Case II

A Gas Fired Calciner kiln which is

seeking to do 90% overall TSR from SRF

and Biosolids BUT cannot run for more

than 4 days without stopping for KILN

BALLS or BUILD UP

Kiln Balls and Build Up

Liquid OK at 26%

A/F and SR not in Kiln Balls Region

Kiln Burner mmtm low at 5 N/MW compared to TML OFT of 10

N/MW

MR in both hot meal and clinker << 1

BUT MI-CFD on the calciner identified probable cause and solution

It was down to the poor combustion of HiCal (50 ash and 50% C 2%

vols) produced from the SPL of the Aluminium Industry, not

combusting well in the KRD and causing balls via low temperature

melts under reducing conditions (F present with the HiCal)

Recommended moving it to the TAD

SO3 Na2O eq MR Cl

Clk 0.14 0.56 0.19 0.00

HM 0.35 0.77 0.35 0.98

VF SO3 2.50 VF K2O 5.96

Oxygen Profile For HiCal Cases O2 = 3.0 % O2 = 3.0 % O2 = 3.0 % O2 = 3.0 %

O2 % O2 %

O2 = 3.4 %

Base Case

HiCal Particles are

in Black Colour

Case 8 16% Stage3 in TA,

HiCal velocity

24m/s

Case 9 32% Stage3 Meal in

TA, HiCal velocity

24m/s, 30 deg angle

(upward)

Case 10 Reduced feed (150

to 100 tph), HiCal

velocity 45m/s

Case 11 In addition to 16% of

Stage 3, 50% From Stage

13 was also moved to

Lower Stage 3 in TAD,

HiCal velocity 24m/s

Big stratification

of O2 and fuel

Base

Case

Case 8 16% Stage3

in TA, HiCal

velocity

24m/s

Case 9 32% Stage3

Meal in TA,

HiCal velocity

24m/s, 30 deg

angle (upward)

Case 10

Reduced

feed (150 to

100 tph), HiCal

velocity 45m/s

Case 11 In addition to 16% of

Stage 3, 50% From Stage

13 was also moved to

Lower Stage 3 in TAD,

HiCal velocity 24m/s

Exit Oxygen % 3.4 3.0 3.0 3.0 3.0

Exit

Temperature

oC 847 840 840 849 865

HiCal

Burnout

% 41 99.6 99.3 99.9 99.6

Analysis of Simulation Results For HiCal

Implemented as case 9 to minimise hot spot potential at the same time as

the burner mmtm was increased to 10 N/MW and the Balls and excessive

build disappeared

Simulations showed how 90% TSR could be achieved via the burner and

calciner.

The biggest issue was stratification in the calciner, which caused poor

calcination and burnout in the KRD side of the calciner and a JAMS was

designed and invoked

Case 12 4.5 & 1.5 tph SRF

Oxygen Profile

Case 13 50-50% SRF

Case 14 4.5 & 1.5 tph

SRF 3 %JAMS

Case 17

50-50% SRF

5%JAMS

Case 15 50-50% SRF

3%JAMS

Case 16

4.5 & 1.5 tph

5 %JAMS

O2 %

Flow

Stratification

reduces with

JAMS (3& 5%)

O2 = 3.8 % O2 = 3.4 % O2 = 3.2 % O2 = 3.4% O2 = 3.2 % O2 = 3.4 % O2 = 3.3 %

Case 18

4.5 & 1.5 tph

5 %JAMS 1jet

SRF Particle Trajectories

BO = 94 % BO = 98 %

BO %

BO = 97 % BO = 99 % BO = 97 % BO = 99 %

Case 12 4.5 & 1.5 tph SRF

Case 13 50-50% SRF

Case 14 4.5 & 1.5 tph

SRF 3 %JAMS

Case 17

50-50% SRF

5%JAMS

Case 15 50-50% SRF

3%JAMS

Case 16

4.5 & 1.5 tph

5 %JAMS

Case 18

4.5 & 1.5 tph

5 %JAMS 1jet

BO = 98 %

One JET Jams better than 2 or 4,

50/50 KRD and TA split best

Case III

A coal fired calciner at 70% TSR

wishes to go to 100% Calciner TSR

with only 2 secs RT

Current Issues CO and @ 75C

increase in PH outlet temperature

100 % Calciner TSR

Impossible many would say.

Calciner far too small at 2 secs RT need at least 6 secs.

However look at the car development

1 litre engines now produce the power or 10 litres 50 years ago

How has the development been done

Via well customised CFD programmes for Engine combustion for both

diesel and gasoline

A customised CFD programme – MI-CFD – can do the same for a small

calciner

SO Tune the Engine give it an MOT What is the Engine

Coal and AFR injection, TA , meal and das riser

The micro mixing or O2 and fuels need to be optimised with respect

combustion and heat transfer to the meal

The is little point in adding volume at the cold end if

the engine is poorly tuned

MI-CFD - Calciner

Schematic of where the focus needs to be to improve calciner performance

and /or drop NOx. Find the hidden enemy – STRATIFICATION and

ELIMINATE OR EXPLOIT IT!!!!

Engine – meal, fuels, burners, kiln

gases and TA

Optimisation and Tuning of this area

via MI-CFD makes a calciner perform

much better in terms of output,

kcals/kg/AFR and emissions

Main body of calciner

where more

combustion and

calcination takes

place, efficacy

depends on the

Engine Tuning

Adding Calciner Volume is often

proposed to improve calciner

performance, however it is at the

COLD end of the calciner and does

not cost effectively improve

performance compared to engine

tuning

DAVID beat Goliath with skill and

knowledge, NOT SIZE

Hot Reburn region

below the TA allowing

optimised reburn and

NHi conversion to N2

and not back to NO

Burnout Time - WHITE ANT - for a 250u Particle as a function of O2 and

Temperature K

0

2

4

6

8

10

12

14

0 1 2 3 4 5 6

% O2

Bu

rno

ut

Tim

e s

ecs

1200 1300 1400 3 secs RT 1100Significance of Temperature and O2 vs RT

N.B simply adding RT at the cold end of the calciner without modifying bottom end does little for burnout

SLC 100% 7 % S petcoke Oxygen and petcoke Temperature and Meal

Petcoke

particles’

trajectories

Hot spots where

meal and petcoke

do not mixed and

are cause of the

high NOx Meal

particles’

Trajectories

Exit

O2

1.2%

Exit

Temp.

905oC

Initially 3 secs

RT, pyro top

added to give 5

secs to run at

100% high S

petcoke

BO%

Calc. %

SLC 100% 7 % S petcoke

Petcoke

burnout

98% Meal particles

calcination – 93%

Petcoke burnout = 95%

Calcination =90%

Little done below this

level.

Generally extending the

calciner volume to

improve performance is

not very cost effective

compared to improving the

early mixing and hence

combustion between TA,

meal and fuel via MI-CFD

without increasing the size

of the calciner.

Plus 93% calcination at

905 C is not a good

calciner.

Replacing

single burner

with 2 burner

down at 60

deg and 75

m/s

Gets 98% BO

and 95% Cal.

at pyro top

100% Calciner TSR

CINAR did initially work for this calciner plant to overcome problems of

poor coal burnout and calcination and very bad build up

This is shown on the next 3 slides, how a low cost modification to the

TA inlets enabled them to overcome the problem and get to @ 70%

calciner TSR with an Engineered Fuel (EF), however the Plant Manager

wanted to get to 100%

.As the calciner has only 2 secs RT this proved to be difficult for them,

due to CO, less of output and elevated PH outlet temperature and we

were asked again to help

From simulations of the current operations it was identified that:-

The EF was being quenched too fast to get a good burnout and its path was

going to the lower O2 regions in the calciner and only burning out to 73%

Simulations of the EF and coal injection points, plus meal splits and a

venturi a series of recommendations were made to get potential to 100%

TSR

Oxygen Mass Fraction [-]

Original

Modified

Original Modified

Burnout % 70 93

Calcination % 70 90

Oxygen Profiles / Fuel Trajectories

Coal / O2

O2 [m/m]

EF / O2

The EF releases

if volatiles fast,

but is then

quenched too

fast by the meal

and then travels

in a low O2

region which

makes the

burnout poor

Near the walls of

there are oxygen

rich areas where

available oxygen

would enhance

the burnout

Case Base Case

Coal Burnout (%) 99

EF Burnout % 73

Total Burnout % 81

Calcination 95

EF particles in O2-Meal particles in Temperature

70%

Profuel Axial Sleeve of

EF injectors

100%

Profuel

O2

T (C)

Adding a

lower meal

inlet

Currently

being

implemented

Best Case Implementation and Feedback

Based on the MI-CFD simulations, modification were proposed to

the EF burners, meal split and the installation of the customized

venturi design not only to stop the EF drop out but to improve the

mixing of the O2 with the EF. The predicted change is below

So the burners have been modified and part of the Venturi has been

installed, with the change below from the Plant info, which shows

already 85% TSR , more output, less CO and better kcals/kg, with a

potential savings of > €1mpa and a pay back on the MI-CFD of @

2weeks

Case 70/30 100%

Coal Burnout (%) 99 -

Eng. Fuel Burnout % 73 84

Calcination % 95 97

Exit O2 % 4.2 3.9

Calciner Exit Temperature (C) 865 866

Year Before part Mod After part Mod Percentage

Clinker tpd 2788 2838 2%

EF firing rate tph 6.8 8.2 21%

PH Exit Temperature 431 416 4%

ID fan O2 ppm 7.5 6.6 14%

ID Fan CO ppm 1110 930 19%

Fuel Comsumption kcals/kg 936 896 5%

Case IV

A Plant is 100% petcoke, but cannot

get above 2.5% S, without running into

build up issues, even though it has a

clinker MR of 0.6 and wishes to go for

100% high S petcoke plus AFR and

meet 600 mg/Nm3

Current issues apart from build up is a

hot spot

Calciner RT @ 2.5 sec

a

O2 [kg/kg]

T [oC]

Meal and Fuel Particles Tracking – current operation

Burnout / Calcination

Av. Burnout: 83% Av. Calc: 75% Fuel Particles &

O2

Meal Particles

& Temperature

Poor burnout/ calcination plus a hot spot

Engine need TUNING

Splitting Meal, Modifying Petcoke Burner and Injecting Alternative Fuels

T [oC]

O2 [kg/kg]

Hotspots at

cone and

cylinder

body

reduced by

better meal

calcination.

60% Meal

mass

injected

below TA

High temperatures

caused by AF´s ,

dropping through

need a customised

venturi

Black:

Petcoke

Pink: SRF

Yellow:

BF 2

Purple:

BF 1

Av. Calcination: 88%

Petcoke Av. Burnout: 98%

SRF Av. Burnout: 95%

Bio Fuel 1 Av. Burnout: 86%

Biofuel 2 Av. Burnout:90%

AF´s falling to kiln hearth

should be avoided by

insert installation in order

to prevent build up

formation .

Case V

A newly built coal fired calciner running

at 800 to 1000 mg/Nm3 needs to hit < 500

mg/Nm3 without SNCR

Needed CINAR Hot Reburn Technology

Essentials of Hot Reburn Retrofit

1300C for 0.15 sec followed by at least 0.5 secs at @ 1000C – meal

quench – at the SR for volatiles < 0.9 to allow for HCN and NHi to

go to N2 and not convert to NO

Care has to be taken to ensure that the TA does not mix in before

this via MI-CFD

For the hot section SIC and Cardox and blasters should be planned

to minimise the impact of build up

The burners need to be optimised with the O2 and NOx profile from

the kiln.

Best Configuration developed via MI – CFD – up to 4 plus variable

PA/Velocity probably optimum for the lowest NOx

However 2 at 30 deg down and @ 60 m/s is giving @ 500 mg/Nm3 at

10% O2

This can be applied to all ILC and also MINOX and RSP’s however

up to 50% of the fuel for the latter 2 has to be taken out and put in

the riser to reburn the kiln NOx and stage the calciner fuel NOx

SLC’s are much trickier , thermal NOx needs to be stopped and the

fuel N staged OR the TA split

NOx to 500 mg/Nm3

The simulation below shows a prediction for normal operation that show the calciner NO generation to give a calciner exit NOx of 850 ppm , with a reburn temperature max < 1200oC;

The reason it is not meeting 500 mg/Nm3 is that the reburn temperature is too low for the 0.5 secs RT between the coal injection and the TA mixing into the reburn zone

Dropping the burners by 3.5 m and optimizing them gets 1300C for 0.15 sec before meal and plus 0.5 before TA mixing

NOx

[ppm]

Coal injection

/Meal injection

@ 12 m (@ 0.5

secs) to TA

mixing

T [oC]

Coal Volatiles and NOx predictions

Plenty of

volatiles

for reburn

at 1300oC

45 m/s

30 deg 105 m/s

30 deg

45 m/s

60 deg

NOx

Predictions

& Tests

Vel Pred. Stack NOx Actual NOx

m/s mg/Nm3 mg/Nm3

45 450 No Test

105 518 350

45 540 550

y = 0.0365x + 192.32

y = 0.1143x + 294.16

y = 0.3172x + 569.05

0.0

100.0

200.0

300.0

400.0

500.0

600.0

700.0

800.0

900.0

1000.0

0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 1400.0 1600.0 1800.0 2000.0

S

t

a

c

k

m

g

/

N

m

3

a

t

1

0

%

O

2

KBE NO ppm

Normal operation, Hot Reburn plus a 1200C > 1 sec RT calciner

Burners Down rebutn 73%, staging - 50%But not fuly optimised

> 1 sec reburnreburn 92% staging 70%

30 deg at

105 m/s

NOx Summary

Hot reburn can and is being applied to ILC, RSP’s and AT calciners,

via MI-CFD to reach < 500 mg/Nm3 without SNCR

Petcoke can be trickier due to its low volatiles

Which results in a higher NOx for the same fuel N

This is due to the char N contributing potentially @ 50% of the NOx

emission, due to the fact that while the NO from the char N is

normally reduced to < 100 ppm by the NOx form the volatiles in the

boundary layer, the low SSA of low volatile petcoke does not allow

this to happen

However the hot reburn 0.15 sec section drives off more volatiles

than the proximate analysis test gives and is working well for ILC

SLC’s of the long vertical type are giving an problem, the key need

is a not reburn after most of the volatile and char NOx has been

formed

This is under development and Plant tests currently being carried out

12000 kms East of here

Generic Calciner for < 500 mg/Nm3 and

90% TSR

Cinar customised HOT

REBURN – 0.15 secs at 1300C

SR volatile < 0.9

Non coating refractory(SiC)

plus blasters

Customised Venturi for AFR

Further reburn and stating

section to allow HCN ->

N2with up to 50% meal

quench, at least 0.5 secs

Opposed TA

inlets or

horseshoe to

enhance mixing

and avoid

stratifications

Enhanced mixing

and combustion

region – hot spot –

controlled by rest

of meal

2.5 secs RT above TA, for

calcination and burnout

AFR and Coal

burners design

and location

customised as a

function of

specification

100% AFR and high S petcoke with 500

mg/Nm3 NOx without SNCR Difficult but can be done, SO REMEMBER

Do not throw CAPEX or SNCR at a problem

All that is needed to succeed is to do:

VF < 2

HM Carbon < 0.1%

HM Cl < 1%

Eliminate Kiln and Calciner Stratification via MOT

M – Micro mixing

O – Oxygen

T – Temperature

Additionally for 500 mg/Nm3

MOT ++

i.e. Volatiles and sub stoichiometric RT

Workout HOW to do it for Low/Zero Capex from

fundamental process knowledge and experience

aided by MI-CFD simulation and interpretation and

IMPLIMENT IT

CINAR delivers solutions to AFR, Process and Emission

Issues in 3 months from Kick Off.

Over 130 projects for cement and lime.

Have Corporate Contracts for all aspects of Process, AFR,

Output and Emissions

Cinar’s Clients- Producers and Manufacturers

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