Loesche Experiences “Optimization & Efficiency improvement in Coal Pulverisers” IOCL – IOCL – 2 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 – Retrofit – Case Case Studies
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 – Retrofit – Case Case Studies
Section 1
Section 1 Introduction to the Loesche Group & Offerings
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:
Employees in Dusseldorf: 300+
Employees worldwide: approx. 600+
Dr Thomas Loesche, Mr Rüdiger Zerbe
Certified according to DIN EN ISO 9001
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 Latinoamericana S. A. Madrid, Spain
LOESCHE GmbH (Head Office) / LOESCHE Automation Düsseldorf, Germany LOESCHE OOO Moscow, Russia
Asia
Africa
LOESCHE South Africa (Pty.) Ltd., Johannesburg South Africa LOESCHE Nigeria Ltd., Lagos, Nigeria
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
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
1.4 Overview of Loesche Energy Systems (LES)
United Kingdom (Power Head Office)
Chennai, India (Manufacturing Unit)
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.
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.
1.4.1 Loesche Energy Systems - Products i.
Coal Mill Upgrade (Classifiers)
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
ii. 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)
1.4.2 Loesche Energy Systems - Products iii. Coal & Biomass Mills
Capable of grinding all types of coal from anthr acite, 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
Section 2
Section 2 Coal Fineness Control & Impact on Boiler Performance
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
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.
Typical XRP Mill Design
2.3.1 Classification – Impact on Combustion
Pulverised Coal Particle Size Distribution Variance
45μm 325 mesh
75μm 200 mesh
No. of particles
75μm
220μm 65 mesh
2.3.2 Classification – Impact on Combustion
Pulverised Coal Particle Size i.
The particle size distribution of the PF will affect the combustion taking place in the boiler
ii.
The larger a particle, the lower its surface area: volume ratio
iii.
Low NOx coal burners designed for 200 mesh (75 micron) particle size
iv. v.
The further from the 200 mesh ideal particle size t he 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
Ideal
75μm 200 mesh
unburnt carbon
220μm 65 mesh
2.4.2 Classification – Impact on Combustion
Pulverised Coal Particle Size Distribution Variance i. ii. iii.
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
iv.
Without increasing mill pressure drop This is only achieved by increasing the RRSB slope
No. of particles
75μm
75μm
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.
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
Section 3
Section 3: Loesche 4th Generation Dynamic Classifier
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
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.
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
3.3 LOESCHE Mill – Lubrication Scheme
Classifier Assembly
Bearing Cartridge – Grease KPF 2G20
Gearbox (if applicable) – Mineral Oil VG320
Roller Assembly
Rocker Arm Assembly
Bearing Lubrication – Grease 2K10
Gearbox
Bearing Lubrication – Mineral Oil VG320
Gearbox Lubrication – Mineral Oil VG320
Hydraulic System
Hydraulic Oil VG68
Section 4
Section 4: Power Plant Coal Mill - Retrofit References
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.)
33
400
350
300
150
100
50
0 Classifier Sales
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
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)
4.1.1 SherCo Power Plant – Case Study 1 i.
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
ii.
Problem/Requirement:
iii.
10% NOx reduction by increasing fineness Existing mills (<68% on 75 micron & <98.5% on 300 micron)
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:
v.
Retrofit 14 x LSKS 36 - Dynamic Classifiers
Project execution data:
Order placed February 2014 Delivered between July – November 2014 Average install duration – 10 days Commissioning & Testing – 9 out of 14 complete
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
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.
4.2.1 Big Sandy Power Plant – Case Study 2 i.
ii.
Plant:
Problem/Requirement:
iii.
Increase throughput by +10% No increase in mill dp, mill kW & No reduction in wear life or loss of fineness
Solution:
v.
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
Target:
iv.
AEP, Big Sandy Power Station, Kentucky, USA 1 x 800 MWe Units, Built 1969 6 x B&W MPS 89 Pulverisers with Static Classifiers
Trial Retrofit 1 x LSKS 39 - Dynamic Classifier
Project execution data:
Order placed January 2012 Delivered between August 2012 Commissioning & Testing complete Dec 2012 Installation space extremely tight (1”) but achieved first time
4.2.2 Big Sandy Power Plant – Case Study 2
Existing v Retrofit
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
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.
4.3.1 Ratcliffe Power Plant – Case Study 3 i.
ii.
Plant:
Problem/Requirement:
iii.
EOn, Ratcliffe Power Station, Nottingham, UK 4 x 500 MWe Units, Built 1968 8 x Babcock 10E10 Pulverisers with Static Classifiers UBC & NOx reduction by increasing fineness Existing mills (<63% on 75 micron & <98.5% on 300 micron)
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:
v.
Retrofit 6 x LSKS 39 - Dynamic Classifier
Project execution data:
Order placed September 2004 – 2008 (all units) Delivered by April of corresponding year Commissioning & Testing complete Dec 2005 Success of 1 st boiler unit led to subsequent 3 boiler units
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
e v e i S g n i s s a P %
PF Fineness Results*: 300 micron:
99.95%
passing 90
150 micron:
97.5%
passing 80
75 micron:
70
72.4% passing
*Client’s test results
60
10
100
1000
50 Mesh - 99.95% Passing
Sieve Size - micron
Pre Conversion - 36t/h , Mean R-R Slope = 41.1° Post Conversion (2005) - 36t/h , Mean R-R Slope = 52.0°
100 Mesh - 97.5% Passing 200 Mesh – 72.4% Passing
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%
