Lignite pre-treatment and blending.

THE EUROPEAN UNION IPA 2013 PROGRAMME FOR KOSOVO*

Feasibility study for environment and other measures on Kosovo B Thermal Power Plant An EU-funded project managed by the European Union Office to Kosovo

Task 4: TRAINING WORKSHOP ON RETROFITTING

Lignite pre-treatment and blending Influence to the Thermal Power Plant operation optimization Ing. Lorik HAXHIU, PhD.

THIS PROJECT IS FUNDED BY THE EUROPEAN UNION

Introduction Coal blending allows utilities to save on generation costs by combining low grade coal with a higher grade coal in order to arrive at a certain calorific value, sulfur content and other parameters. Many new plants are being built with the capabilities of blending coal and older plants have to convert and to adapt the ability to do so.

Over the years utilities have adopted several different methods for blending coal depending on their needs and availability of coal. The method selected depends upon the site conditions, the level of blending required, the quantity to be stored and blended, the accuracy required, and the end use of the blended coal.

Blending can take place at the coal mine, delivery system, coal yard, and the power plant.

Coal Mine

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Transport

Coal Yard

Feasibility study for environment and other measures on Kosovo B Thermal Power Plant

Power Plant

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Current status of coal supply chain The Coal Production Division (CPD) supplies the Kosovo B power plant with required / planned quantities but without contractually specified quality parameters. The CPD delivers the quantities and quality is delivered based on best effort to blend coal on mine site by combining operation of different bench BWEs (knowing that best coal qualities and on clearly separated top bench and lowest qualities on the bottom of the seam where the separation of coal and base clay material is not so clear).

The CPD is responsible for the whole supply chain from the mine site, collecting belt conveyors, main belt conveyors, crushing/separation station, coal yard and stacker/reclaimer machines and up to Delivery Point on bridge/inclined belt conveyor from the coal yard to the Kosovo B power station (the internal coal supply system).

The coal supply to Kosovo B is done in three options: 1) from the coal yard, 2) from the belt conveyor (directly from the mines) or 3) a combination of both.

The only installed online monitoring system located on bridge conveyor from the coal yard to the Kosovo B power plant is out of operation for couple of years now. The delivered coal quantities are measured by survey and quality is measured by daily sampling and laboratory analysis performed by INKOS Insitute.

There are many limiting factors today that impair the optimization of coal handling system, such as: - Difficulties in implementation of the Mine plan (issues with overburden removal due to resettlement progress not allowing for proper mine bench development and advancement) - Lack of geological block model (based on entire coal column) which is easily accessible by planning and operational staff (for scheduling of MME) - No communication between BWE and S/R operators - Lack of continuous / online monitoring system on several points - Lack of global positioning system on BWEs - No organizational structure to deal with quality delivery planning on daily/weekly basis.

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Future coal supply contractual requirements The Sibovc lignite quality parameters (8500 kJ/kg) are in general better than those used for the design of Kosovo B power plant (7500 kJ/kg); there is also lower ash content but higher sulphur content, that is important parameter in regards to emissions.

With ongoing efforts for construction of a new modern 450 MW power plant (Kosova e Re) designed for Sibovc coal parameters, the CPD will be obliged to sign and comply with strictly prescribed Lignite Supply Agreement, meaning it has to follow contractually agreed quantities and qualities within specified quality margins.

As CPD will be a single coal supplier for Kosovo B and Kosova e Re, it will be necessary to construct or expand the exiting coal yard to also meet additional days of guaranteed reserves. It will be also necessary to implement a state-of-the-art coal yard management system with dedicated Coal Quality Management unit (for coordination and supervision of the LSA) The same applies for optimization of Kosovo B operation and efforts to increase the overall efficiency of the plant, as well as achieving the emission limit values.

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Lignite Supply Chain Mine Site (Sibovc Southwest) to TPP Kosovo B

Bunkers / Feeders Coal Yard Transport

Mining

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The future quality of coal supply

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The future quality of coal supply Range (kJ/kg) 6500 ‐ 7000 7000 ‐ 7500 7500 ‐ 8000 8000 ‐ 8500 8500 ‐ 9000 9000 ‐ 9500 Total

Distribution % 0.12 1.12 6.85 34.25 47.13 10.54 100

Weighted Average (kJ/kg) 6,883 7,334 7,846 8,269 8,759 9,114 8,548

Reference LHV (kJ/kg)

8,548

Range

Min 8,000

Reference Moisture Ash Volatile matter Fixed carbon

% % % %

45.0 13.85 25.52 12.79

Range Min 33.8 10.9 21.2 9.3

Reference Carbon Hydrogen Nitrogen Chlorine dry basis Sulphur Oxygen Moisture Fluorine dry basis

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% % % % % % % mg/kg

24.22 6.54 0.49 <0.01 0.91 51.4 45.0 63.25

Feasibility study for environment and other measures on Kosovo B Thermal Power Plant

Max 9,500 Max 47.1 28.7 28.0 16.1 Range

Min 20.2 5.7 0.40 <0.01 0.65 33.8 33.0

Max 27.3 7.2 0.75 <0.01 1.98 47.1 125.0

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Optimized Coal Handling Coal handling systems are an integral part of a complete flow and quality management system.

In the recent years, the main focus was on the optimization of single parts of this system, such as mine equipment scheduling, or blending at the coal yard.

Now, however, complete system optimization, including the integration of all subsystems, is required to deal with the increased efficiency of modern coal-fired power plants and secure the coal supply in sufficient quantity and quality.

Main parts of the system: -

Mine site

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Transportation

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Coal yard

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Power plant

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Components of an Integrated coal management system Mine site

Transportation

Exploration & Mine Planning

Production Planning

(Exploration drilling campaign with assessment of the entire column on the borehole – not just sections / average values) also total analysis of lignite quality parameters.

Production Schedule: • Year • Month • Day

Detailed Geological Block Model optimized with exploitation in mind.

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Dispatching System Central Control System

BWE Fleet Management

Coal Yard

Power Plant

Dispatching System Belt Conveyor System redesigned with ability to blend on collecting / transfer stations.

Dispatching System

Production Schedule: Month Week Day Central Control System

Production & Control System Power Plant

Local Automation System for Stacker/Reclaimer

Local Automation System for BWEs

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Optimized Coal Handling â&#x20AC;&#x201C; Mine Site

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Optimized Coal Handling – Mine Site

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Feasibility study for environment and other measures on Kosovo B Thermal Power Plant

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Detailed Geological Block Model based on assay data obtained from analysis of the total column of the borehole

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Optimization of BWE scheduling with blending in mind

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Communication channel between Mine Site and Coal yard

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Optimized Coal Handling â&#x20AC;&#x201C; Coal Yard

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Blending techniques Blending of coal can be done in different ways to achieve different outcomes.

Blending is rather more complicated than just the mixing of two or more coals together. However, homogenization goes even further than blending for those who need a truly optimized combination of coals.

The difference between blending and homogenizing:

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Blending: the mixing of two or more different materials to produce a blend with a new average level of certain parameters. This can be done to bring together layers of material brought in from different deliveries. The total of the mix has a predicted average quality, although there will be variation within different regions of the mix.

•

Homogenizing: the combination of different mixtures to reduce the variation throughout relative to the average. This requires more effort and more dedicated equipment and is therefore more expensive than blending.

One of the simplest ways to physically blend coals is to pile the coals together. Obviously, to achieve an effective mix, there has to be control over how the coal is mixed and combined.

There are two general ways of blending on site: •

blending in advance – creating the blend in a pile as the coal is delivered, by depositing the different coals into the same pile or hopper in a controlled manner;

•

blending on demand – storing coals separately but reclaiming them into the mix as they are required for delivery to the boiler.

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Feasibility study for environment and other measures on Kosovo B Thermal Power Plant

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Coal Sampling In order to ensure that the characteristics of a coal or blend meet requirements, sampling and analysis is required at several steps during the coal delivery chain: •

to evaluate and confirm the characteristics of the coals before blending;

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to confirm that the blend achieved is as desired;

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in automated blending systems, to confirm or to adjust the blending ratios to ensure the blend remains consistent; and

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in some cases, the characteristics of the coal feed, such as sulphur content, are required to be recorded for compliance purposes.

Sampling •

The objective of coal sampling is to obtain a small amount of coal for detailed analysis which will be assumed to be representative of all the coal in that batch or shipment. Ideally the sample should reflect the overall variability within a coal batch. For materials such as coal, representative sampling can be a challenge.

•

In coal mines, samples may be taken after mining and before any sorting or blending. In coal handling and blending facilities, samples are commonly taken from the conveyors, as the coal is taken from the bins or stockpiles to the final transit point before combustion. Samples are grabbed, dropped or scraped from the belt into a container which is then removed for analysis

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International Standards for Sampling and Sample preparation International and national standards: ISO standards, ASTM International, British standards, Chinese coal standards, Indian standards, South African national standards, Australian standards.

1. Sampling

4. Sample preparation

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General principles of sampling

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Constitution of a sample

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Establishing a sampling scheme

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Air drying

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Precision of sampling

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Sample reduction

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Sample division

2. Methods of sampling

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Sample mixing

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Sampling from moving streams

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General rules of sample preparation

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Sampling from stationary coal

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Manual sampling

5. Bias testing

3. Advances in mechanical sampling systems •

Automatic sampling systems

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Collecting the full cross section

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The sampling system crusher

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Sampling error

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Methods of testing for bias

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Stopped-belt sampler

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Automatic (mechanical) cross-â&#x20AC;?belt sampling system

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Standard laboratory Analysis of Coal Proximate analysis

Miscellaneous analysis

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Moisture

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Chlorine

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Ash

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Mercury

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Volatile matter

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Mineral matter in coal

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Fixed carbon

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Ash fusibility

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Coal swelling property

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Hardgrove Grindability index

Ultimate analysis •

Carbon and hydrogen

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Nitrogen

Instrumental analytic techniques

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Sulphur

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X-ray spectroscopy

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Calorific value

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Electron microscopy

Ash analysis

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Atomic spectroscopy

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Preparation of coal ash

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Mass spectroscopy

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Major and minor elements

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Neutron activation analysis

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Trace elements

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Online analysis systems

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Stockpile blending in advance Stacking coal in these formations requires specialist equipment â&#x20AC;&#x201C; a stacker

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Stockpile Blending in advance Perhaps the most simple and low cost method of coal blending is to place different coals into one single pile. This is known as â&#x20AC;&#x2DC;stockpile blendingâ&#x20AC;&#x2122;.

The pile grows as layers of different coals are added in horizontal layers as shown.

The different colors indicate the different coals as they are added to the pile. The positioning and thickness of the layers allows the coals to be stored in ways that allow blends to be created as part of the reclamation process.

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Feasibility study for environment and other measures on Kosovo B Thermal Power Plant

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Kosovo B Coal Yard

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Computerized Coal-yard management systems

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Volume measurement

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Stockpile management

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Blending by Reclamation The more layers of coal there are in a stockpile, the greater the blending effect. However, the homogeneity of the mix will still be limited by the thickness of the layers and the subsequent movement of the coal between collection from the stockpile and delivery to the boiler.

In some cases, simple layering is not enough to create an even blend. The blending of the coal can be improved during the reclamation process. In fact, blending can often be more dependent on the reclamation method than on the method of stacking.

The simplest method is probably the bucket-wheel reclaimer which uses buckets in sequence passing through the coal pile to gather the coal from the desired section, usually containing a mix of coals.

The reclamation of coal with any of this equipment can be achieved by bench reclaiming â&#x20AC;&#x201C; where the bucket or scraper passes at a fixed height across the length and or width of a coal stockpile; or by block reclaiming â&#x20AC;&#x201C; where the bucket or scraper gathers coal from one or more layers at a fixed level over a pre-determined area of the pile. The method will depend on the layout of the coal stockpile and the blend required and this will be controlled by the coal stockyard manager.

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Lignite Supply Agreement

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Key elements of Lignite Supply Agreement (LSA) 1. Definitions

9. Price

2. Effective Date, Term, Supply Period

10. Environmental Remediation

3. Extension for Change in Law

11. Reports to ICMM

4. Supply of Lignite

12. Billing and Payment

5. Measurement

13. Risk of Loss, Title

6. Assurances as to Supply

14. Taxes

7. Operating Procedures

15. Insurance

8. Quality; Off-Spec Deliveries

16. Representation

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Contract Lignite Quality

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Recommendations / Summary •

Geological Exploration Program (based on detailed analysis of the entire coal seam borehole column)

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Preparation of Detailed Geological Block Model

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Feasibility Study for Lignite Supply Agreement implementation

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Mine production planning and optimization, equipment scheduling with blending in focus

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Reorganization of coal colleting and delivery belt conveyors with blending in focus

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Definition of sampling points before stockpiling

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Definition of delivery parameters and setting up system for sampling and analysis of the agreed parameters

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Selection of most appropriate standards / methods for sampling and analysis

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Establishment of Coal Quality Unit

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Monitoring and Reporting between contractual parties

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Training program

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Questions and Discussion

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