Highest efficient supply for coal-fired power plants

ABB’s support to power plant operators to handle their use of coal more efficiently and sustainably
Regardless of the increasing number of discussions on regulations of greenhouse emissions, coal will remain to be the most important source of fossil primary energy for the next decades on a global base. In order to face these future challenges, ABB provides technology support to power plant operators with trapezoidal stockpiles to handle their use of coal more efficiently and sustainably.
From mine to plantCoal handling systems are an integral part of a complete material flow and quality management system
While in recent years, the main focus was on optimisation of single parts like mine planning or advanced automation solutions now a seamless integration of all sub-systems and an overall optimisation from the mine to the power plant is requested.
The increased degree of efficiency of modern coal power plants requests an integrated coal handling management system to secure the coal supply in the requested quantity and quality.
In order to cover these requests, ABB has developed a modular system  The production management level includes the tools for managing the mine, haulage and trade process in regard of fulfilment of contracts (quantity and quality), production management, maintenance and asset management. This level provides also necessary interfaces to ERP systems like SAP and others.
The Stockyard Management System (SMS) which will be described more in detail later on enables a fully automated operation of the whole stockyard from a central control room and consists of the following modules:

Pile monitoring and visualisation
Material tracking
Quality management
Autonomous stacking/reclaiming.
The local automation level covers all basic control functions, mostly implemented on the stockyard equipment itself. It includes instrumentation, electrification and automation scope on a local PLC for operator controlled stockyard machines.
This system can be customised to the needs of determined projects like:

Stockyard systems for lignite power plants (connected with the mine by rail or an overland conveyor system)
Export or import coal terminals with ship and train loading and unloading
In plant coal handling systems.
Stockyard management descriptionIn order to achieve a fully automated operation from a central control room, the operator must know at every time how much coal with a certain quality is at what place, even it is in a surge bin, on a belt or on the stockpile.
These requirements can be met by an exact database of material quality information in the transportation and stockpile model which monitors online the material flow.
The necessary input for the model is delivered by laser scanners and positioning systems mounted on the stockyard machines which allow the autonomous operation of the machines as well.
The scanners can provide surface information from its environment which will be used to recalculate the model. This solution enables a nearly real time update of the pile surface even after material movements due to environmental influences like storm or heavy rain or due to the use of mobile machines as grader or bull dozer.
Furthermore, these devices support the interface to the BulkExpert System which enables a fully automated stacking and reclaiming. The coal can be stacked and reclaimed by various methods in order to provide an adequate treatment of the material and perform the mixing and blending process.
Pile monitoring and visualisationThe stockpile monitoring and visualisation module records material movements to and from a stockpile and calculate the material distribution on a stockpile accordingly. The module supplies information about the material on the stockpile and its shape as well as the different properties (quality) of the material. Material distribution on the stockpile will be calculated with a computational module-based on the information of the module material tracking, stacking and reclaiming technologies and the 3D-laser scanning results. The stockpile visualisation component offers a graphical presentation of the information stored in the stockyard management system in a modern browser technology. The visualisation shows an overview over all stock piles on the job site.
For a detailed analysis of the stockyard, it is possible to zoom and turn the view. The view can be adjusted from different viewpoints and separate piles can be selected.
Stockpiles can be splitted into small individual virtual piles. These sections are shown with its borders in Fig 4.
Additionally, pile areas with its properties, slice or cut views can be shown (Fig 5).
Material trackingThe module “material tracking“ supports the operator in monitoring the material flow of bulk material and supplies real time stockpile tracking by tonnage and quality. The main functions are:

Gathering information of material type, quality and its specifications at the inlet of the stockyard
Monitoring of masses/volumes on the way to the stockpiles via belt conveyors
Tracking of materials to the discharge point
Dynamic display of belt load with colour-coded information about material properties
Balances of input, stored and output material mass/volume
Data exchange to overriding MES systems.
The module manages the distribution on the stockyard to enable an efficient usage of the complete area with determined coal quality in every stock pile (Fig 6).
Coal qualityAn integrated coal quality management system is in particular important where power plants are supplied by different mine sites with variable coal parameters like:

Calorific value
Ash content
Moisture content
Content of sulphur, silicon, aluminium and potassium.
Modern generating units need a certain coal quality with tight variations in order to ensure an efficient burning process. Significant deviations can cause slagging processes to the point of unscheduled downtimes of the whole unit with remarkable loss of production.The coal quality parameters can be detected offline by drill samples and laboratory analysis, or online with radiometric methods.
For the quantity measurement, belt scales or belt volume scanners can be used.
Quality information (e.g. RFID, bar code, electronic transmission per file or freight papers) has to be handed over by the supplier or/and can be measured online right away the loading point and often verified after the discharge point.The quality can be assured by blending the coal within the mine (combination of mining units, shifting heads and coal lines), on the stockyard during the stacking or reclaiming process or in the in plant storage and feeding system.
Realise advantagesBy implementing stockyard management system, power plant operator achieves many advantages. First, the modular system enables a seamless integration of the coal flow from mine to plant which is cutting the effort in material handling. Furthermore, the fully automated operation of the stockyard devices significantly reduces longitudinal travelling and decreases downtimes by predefined alternative routing.
Additionally, the intelligent power plant supply by monitored blended material qualities enables a better coal firing which ultimately will improve the carbon footprint.

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