Coal Mill Technologies_brishank Srivastava

Loesche Experiences “Optimization & Efficiency improvement in Coal Pulverisers” IOCL – 2nd All India Servo Power Meet 2016, Ghaziabad (INDIA) Presented by: Brishank Srivastava (Loesche Energy Systems India Pvt. Ltd.) Vishal Agarwal (Loesche India Pvt. Ltd.)

Agenda 1. Introduction to the Loesche Group 2. Coal Fineness Control & Impact on Boiler Performance

3. Loesche 4th Generation Dynamic Classifier and Lubrication Requirements. 4. References 5. Dynamic Classifier Retrofit – Case Studies

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Section 1

Section 1

Introduction to the Loesche Group & Offerings

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1.1 Introduction – Loesche Group

 LOESCHE GmbH is a privately owned company founded 1906 in Berlin, Germany  Head office based in Dusseldorf, Germany  Main shareholder: Dr Thomas Loesche  Management:

Dr Thomas Loesche, Mr Rüdiger Zerbe

 Employees in Dusseldorf: 300+  Employees worldwide: approx. 600+  Certified according to DIN EN ISO 9001

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1.2 Loesche Worldwide

America • LOESCHE America,

Inc. Pembroke Pinkes, Florida, USA • LOESCHE Energy

Systems, America. Branch Office Pittsburgh, Pennsylvania,USA

Europe  LOESCHE Energy

Systems Horsham, UK  LOESCHE Latino-

americana S. A. Madrid, Spain  LOESCHE GmbH

(Head Office) / LOESCHE Automation Düsseldorf, Germany  LOESCHE OOO

Moscow, Russia Loesche Image

Africa  LOESCHE South

Africa (Pty.) Ltd., Johannesburg South Africa  LOESCHE Nigeria

Ltd., Lagos, Nigeria

Asia  LOESCHE Middle East

Tehran Branch Office Tehran, Iran  LOESCHE Energy Systems India (Pvt.) Ltd, New Delhi, India  LOESCHE India (Pvt.) Ltd. New Delhi, India  LOESCHE Mills Ltd.

Shanghai & Beijing, PRC  LOESCHE GmbH Vietnam

Branch Ho Chi Minh City, Viet Nam 5

1.3 Purpose of Loesche Energy Systems (LES)

LES is the Centre of Excellence for coal mill application in the power utilities industry.  In early 2004 Loesche GmbH identified an opportunity to diversify into the Power Market 

 Consequently a special purpose vehicle name LES was formed (2006).  This approach allowed the recruited boiler specialists to focus the Loesche products more directly into the Power industry

 In addition develop novel solutions to some of the current industry bottlenecks

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1.4 Overview of Loesche Energy Systems (LES)  Loesche Energy Systems Ltd (LES) is a 100% owned subsidiary of Loesche GmbH  Founded in February 2006 in Horsham, West Sussex, United Kingdom  LES is the coal mill technology holder for the Loesche Group. United Kingdom (Power Head Office)

 LES have introduced two new daughter companies in 2014 to expand geographical presence in the Pittsburgh(USA) and New Delhi (India)  LES has its manufacturing base in Chennai, as Loesche Energy Systems India (P) Ltd.

Chennai, India (Manufacturing Unit)

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1.4.1 Loesche Energy Systems - Products i.

Coal Mill Upgrade (Classifiers)       

ii.

Referenced retrofit on BTM‘s, HP, RP, MPS & E mills Increases mill throughput by upto 20% Increases fineness by 5-10% on 75 Micron Eliminates retention on 300 Micron Reduces LOI by approx 50% Reduces Nox by 12-15% Over 400+ retrofits completed globally

Advanced Modelling & Scanning  Combustion optimisation through two phase modelling

and simulation of furnace combustion to determine optimised burner and after air port design to minimise the formation of NOx.  SCR & SNCR flue gas flow modelling leading to optimisation of sorbent injection points to substantially reduce running OPEX (payback less than 12-18 months)  FGD flue gas flow modelling leading to optimisation of limestone injection points to substantially reduce running OPEX (payback less than 12-18 months)

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1.4.2 Loesche Energy Systems - Products iii. Coal & Biomass Mills  Capable of grinding all types of coal from anthracite,   

   

bitumous, sub bitumous and lignite Capable of grinding all types of pelletised biomass (wood or straw) 2, 3 and 4 grinding roller mills Capacity up to 250 t/h @ fineness exceeding 85% on 200 mesh Drive motors up to 1,200 kW Supply of coal mills for NEW BUILD and RETROFIT Notable active markets, China, India, South East Asia and Poland Clients include DH, Doosan Babcock, Ansaldo, Rafako etc

iv. Novel Power Plant Solutions  Loesche has supplied grinding terminals for IGCC and

Oxyfuel  Current developments include high coal moisture enhancement process at minesite or front end of power plants  Notable active markets, South Korea, Australia, Indonessia & Nigeria

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Section 2

Section 2

Coal Fineness Control & Impact on Boiler Performance

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2.1 Power Industry Fuel Based Challenges Observations from the trends are 1. New emissions legislation  To reduce NOx, SOx, SPM etc. (Owing to MOEF Norms issued in December 2015 – Compliance by December 2017)

2. Change in Coal Flows  Due to cost reduction drives (cheaper coals)  Due to Use of Alternative fuels having different grindabilities

3. Upgrade of Old Power stations  Efficiency improvement  Reduction in unburnt carbon

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2.2 Classification – Historical  Traditional Static Classifier Design  Power plant coal mills were historically supplied with 1st generation static classifiers

 These were fit for purpose when considering the station drivers of the day, namely  Stable/reliable combustion  Efficient combustion  Emission regulations were negligible  Drive was to minimise LOI and CO  Static classifiers were cone type with external, manually adjustable fineness control static blades  Target fineness was 70% passing 75 micron with a PSD slope of 45º, which gave 99% on 300 micron  Classification is achieved by changes in air velocity and direction.  The product size can be altered to some extent by changing the angle of the vanes, but the efficiency is low and static classifiers can be regarded more as grit separators than efficient classifiers. Loesche Image

Typical XRP Mill Design 12

2.3.1 Classification – Impact on Combustion  Pulverised Coal Particle Size Distribution Variance

45μm 325 mesh

75μm 200 mesh

220μm 65 mesh

No. of particles

75μm

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2.3.2 Classification – Impact on Combustion  Pulverised Coal Particle Size i. ii. iii. iv. v.

The particle size distribution of the PF will affect the combustion taking place in the boiler The larger a particle, the lower its surface area: volume ratio Low NOx coal burners designed for 200 mesh (75 micron) particle size The further from the 200 mesh ideal particle size the worst the impact on the combustion The surface area to volume ratio affects how the particle will combust – primarily, how fast it will burn

vi.

Particles that are too large/coarse have an insufficient surface area to combust fully, as well as being physically excessively heavy, and will drop into the ash at the bottom of the furnace

vii.

Particles that are too small/fine have an excessive surface area and will combust too rapidly, increasing the flame temperature and catalysing the formation of increased levels of NOx

NOx formation

45μm 325 mesh Loesche Image

Ideal

75μm 200 mesh

unburnt carbon

220μm 65 mesh 14

2.4.1 LOESCHE 4th Generation Dynamic Classifier  Solution – 4th Generation Dynamic Classifier

Secondary classification: It is achieved by horizontally active forces between static flaps and rotating rotor blades. Material is thrown against the static flaps and falls back onto the table via the grit cone. This is coupled with centripetal and horizontal forces imparted by the rotor blades.

Primary classification in the mill by vertical forces - upstream gas flow versus gravitation (weight and density) . oversized particles are recirculated to table for regrinding and getting into liftable product range.

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2.4.2 Classification – Impact on Combustion  Pulverised Coal Particle Size Distribution Variance i. ii. iii.

iv.

The slope of the graph is broadly analogous to the variance of the distribution To put it simply, the RRSB slope gets steeper as the distribution of particle size gets narrower Thus the goal of any classifier design is to:  Minimise/eliminate all particles greater than 250 micron  Minimise all particles less than 45 micron  Without increasing mill pressure drop This is only achieved by increasing the RRSB slope

No. of particles

75μm Loesche Image

75μm 16

2.5 LSKS Classifier – Benefits Fineness:

Throughput:

1.

1.

2. 3. 4.

Steep grain size distribution curve typ. 54 to 57º Reduced coarse end fineness typ. trace on 50 mesh Retrofit applications HAVE achieved > 55% reduction in LOI Retrofit applications HAVE achieved > 15% reduction in NOx

2. 3.

Reduction in system pressure drop, which allows…. Increase of mill throughput by typ. 15-20% Allows for return to n+1 operation in USA, India and RSA

Flexibility 1. 2. 3. 4.

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Ability to change classifier speed online allows…. Optimization for fineness when coal is good (increase speed) Optimization for throughput when coal is bad or wet (reduce speed) Optimization when co-firing BIOMASS

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Section 3

Section 3: Loesche 4th Generation Dynamic Classifier

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3.1 LSKS Dynamic Classifier - Overview I.

LSKS Dynamic Classifier is the 4th generation of Loesche rotary classifier.

II. Original development and trials in power undertaken in early 1990’s. III. Over 400+ retrofitted to existing stations in the last 5 years. IV. All type of mills have been retrofitted (MPS, HP, E-Mills, XRP, RP and Ball Tube Mills) V. NFPA 85 and Atex compliant VI. ZERO performance liquidated damages to date

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3.2 LSKS Classifier Components i. ii.

PF Outlet duct.

iii. Classifier rotor cpl.

Coal feed chute. v. Drive motor.

vi. Classifier housing.

iv. Static guide vane.

vii. Grit cone. Loesche Image

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3.3 LSKS Classifier Lubrication LOESCHE DYNAMIC CLASSIFIER - LSKS

 Grease lubrication of bearing cartridge:      

 

Grease reservoir with level sensor Continuous low level alarm will trip the system after X hours (usually 8 hours) Single outlet grease pump Grease splitter (50:50) 2 lines into (upper / lower bearing) Pump runs for 10 minutes, shuts down for 50 minutes and restarts as long as classifier is running The bearing temperature is monitored continually by temperature sensors Grease type  KPF 2G20 or comparable

Illustration Loesche Image

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3.3 LOESCHE Mill – Lubrication Scheme  Classifier Assembly  Bearing Cartridge – Grease KPF 2G20  Gearbox (if applicable) – Mineral Oil VG320

 Roller Assembly  Bearing Lubrication – Mineral Oil VG320

 Rocker Arm Assembly  Bearing Lubrication – Grease 2K10

 Gearbox  Gearbox Lubrication – Mineral Oil VG320

 Hydraulic System  Hydraulic Oil VG68

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Section 4

Section 4: Power Plant Coal Mill - Retrofit References

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5.1 LSKS Reference List 450

Mil Type/Design

No. of Retrofits

XRP

200

B&W

63

Babcock (E-Mills)

62

BBD Mills

24

250

Loesche

38

200

Others (MPS/IHI/ZGM etc.)

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400

350

300

150

100

50

0 Classifier Sales

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2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

4

14

24

43

66

94

117

169

190

210

224

232

307

392

420

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Section 4

Section 4: Dyn. Classifier Retrofit - Case Studies  SherCo – 2 x 750MW (Built in 1970s)  Big Sandy – 1 x 800MW (Built in 1969)  Ratcliffe – 4 x 500MW (Built in 1968)

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4.1.1 SherCo Power Plant – Case Study 1 i.

ii.

Plant:

 Xcel, Sherborne County Power Station, Minnesota, USA  2 x 750 MWe Units, Built 1970’s  14 x Alstom HP 1003 Pulverisers with Static Classifiers

Problem/Requirement:  10% NOx reduction by increasing fineness  Existing mills (<68% on 75 micron & <98.5% on 300 micron)

iii.

Target:  Increase fineness to +75% on 75 micron & +99.9% on 300 micron  No increase in mill dp, mill kW & No reduction in wear life.

iv.

Solution:  Retrofit 14 x LSKS 36 - Dynamic Classifiers

v.

Project execution data:    

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Order placed February 2014 Delivered between July – November 2014 Average install duration – 10 days Commissioning & Testing – 9 out of 14 complete

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4.1.2 Sher Co Power Plant – Case Study 1  Results Target  Increase fineness to +75% on 75 micron & +99.9% on 300 micron  No increase in mill dp, mill kW & No reduction in wear life.

PGT (9/14)  Increase fineness to +89% on 75 micron & +99.9% on 300 micron  No increase in mill dp, mill kW & No reduction in wear life.

 Additional Comments 

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

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Installation, commissioning and optimization of the Dynamic Classifier retrofit on both units is completed.. Sherco achieved their NOx objectives with only 9 of the 14 DC's installed. Our team was complimented several times on their approach and technical input, they achieved an excellent professional working relationship with station employees. LES met and exceeded tight deadline schedules required by the plant.

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4.2.1 Big Sandy Power Plant – Case Study 2 i.

ii.

Plant:

 AEP, Big Sandy Power Station, Kentucky, USA  1 x 800 MWe Units, Built 1969  6 x B&W MPS 89 Pulverisers with Static Classifiers

Problem/Requirement:  Trial to prove increased throughput  Ability to return boiler unit to n+1 mill operation and avoid unit de-rate during planned & unplanned mill outages

iii.

Target:  Increase throughput by +10%  No increase in mill dp, mill kW & No reduction in wear life or loss of fineness

iv.

Solution:  Trial Retrofit 1 x LSKS 39 - Dynamic Classifier

v.

Project execution data:    

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Order placed January 2012 Delivered between August 2012 Commissioning & Testing complete Dec 2012 Installation space extremely tight (1”) but achieved first time

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4.2.2 Big Sandy Power Plant – Case Study 2  Existing v Retrofit

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4.2.3 Big Sandy Power Plant – Case Study 2  Results Target  Increase throughput by +10%  No increase in mill dp, mill kW & No reduction in wear life or loss of fineness

PGT (9/14)  Increase throughput to +19.3%  No increase in mill dp, mill kW & No reduction in wear life (ongoing) or loss of fineness.  Eliminated the mill reject/dribbling issues  Reduced the specific power consumption of the mill by over 10%

 Additional Comments    

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LES met and exceeded tight deadline schedules required by the plant. Extremely tight area for install – distance between mills were limited Use of laser survey by LES enabled full installation plan to be determined This led to zero clash issues during removal & installation.

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4.3.1 Ratcliffe Power Plant – Case Study 3 i.

ii.

Plant:

 EOn, Ratcliffe Power Station, Nottingham, UK  4 x 500 MWe Units, Built 1968  8 x Babcock 10E10 Pulverisers with Static Classifiers

Problem/Requirement:  UBC & NOx reduction by increasing fineness  Existing mills (<63% on 75 micron & <98.5% on 300 micron)

iii.

Target:  Increase fineness to +70% on 75 micron & +99.9% on 300 micron  No increase in mill dp, mill kW & No reduction in wear life.

iv.

Solution:  Retrofit 6 x LSKS 39 - Dynamic Classifier

v.

Project execution data:    

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Order placed September 2004 – 2008 (all units) Delivered by April of corresponding year Commissioning & Testing complete Dec 2005 Success of 1st boiler unit led to subsequent 3 boiler units

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4.3.2 Ratcliffe Power Plant – Case Study 3 Results Coal Flow:

Ratcliffe - LSKS Rosin Rammler Size Distribution

36.0 (Te/hr)

99.98

Contract Coal:

99.9

Bituminous

99

% Passing Sieve

 PF Fineness Results*:  300 micron: 99.95% passing 90

 150 micron: 97.5% passing

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 75 micron: 72.4% passing  *Client’s test results

70 60

10

100

Sieve Size - micron

Pre Conversion - 36t/h , Mean R-R Slope = 41.1° Post Conversion (2005) - 36t/h , Mean R-R Slope = 52.0°

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1000

50 Mesh - 99.95% Passing 100 Mesh - 97.5% Passing 200 Mesh – 72.4% Passing

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4.3.3 Ratcliffe Power Plant – Case Study 3 Project Summary Increased Boiler Combustion Efficiency Independent testing found that the LSKS Dynamic Classifier gave a substantial reduction in un-burnt carbon due to the greatly improved particle size and distribution At Ratcliffe an average reduction in UBC (at normal excess air levels) of

around 62% was achieved. Subsequent results at other stations have led to LES often confirming a UBC reduction of 40-50% In addition it was found that LSKS Dynamic Classifier directly allowed a reduction in NOx whilst increasing overall boiler efficiency. This was achieved by reducing excess air levels at the burner (the unit operator was able to achieve this due to the stabilised combustion). 12 – 15%

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Thank you for your attention ! Questions or Comments?

Contact: Brishank Kumar Srivastava Phone: +91 9910018792 E-mail: [email protected] Loesche Image

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