New approaches

Marco Bertorelle, Bedeschi S.p.A., Italy, presents two case studies of coal storage projects undertaken in the power plant industry.

Coal is one of the most important energy sources in the world. It satisfies nearly 45% of the energy requirements of Asia and more than 50% of countries, such as China and India.

The surge in energy demand in recent years has led to an increase in coal’s share of the total energy requirements worldwide. The application of modern technology in treating smoke, for example, has greatly reduced the environmental impact of coal-fired power plants. This has resulted in more coal-fired power plants in Europe and also the US.

With the high quantities of coal being used, the bulk material handling market requires ever more efficient and economical methods of storing coal.

Case study: coal storage at the Virginia City Hybrid Energy Centre, US
Bedeschi has provided the design, engineering and complete supply of equipment to the development of the 600 MW Virginia City Hybrid Energy Centre, which entered commercial operations on 10^th July 2012. Virginia City is one of the cleanest coal-fired power plants in the US. It is operated by Dominion Energy. The circulating fluidised bed unit will use coal and up to 20% biomass for its fuel.

The contract issued with Bedeschi included the supply of all the mechanical components and the electrical and control systems for two STK 31/1400 linear stackers and two PAL PD 260/22+220/12 double arm lateral portal reclaimers for coal handling at the power plant. The stackers have been designed for 950 tph and the reclaimers have been designed for 860 tph.

This project is unusual because Dominion Energy blends low-BTU coal with high-BTU coal on the field belt conveyor, which is fed by Bedeschi reclaimers.

Due to the method of blending, Bedeschi and Dominion Energy engineers were required to work closely together in order to develop the software operating program. This software automatically adjusts the quantities of low-BTU coal and high-BTU coal. This maintains and optimises heat value within a desired range and also avoids any unexpected fluctuation. The ability to change the blend of low-BTU and high–BTU coal allows the Dominion Energy boilers to operate at high efficiency levels, while also maintaining acceptable emission levels.

Dominion Energy has made further savings by eliminating the need for expensive multiple coal bunkers and the required extraction feeders that would need to be installed beneath them. Coal silos are still used, however, to fine tune the coal blend as it is conveyed directly from the storage piles.

Case study: covered coal domes at the South Brindisi ENEL power plant, Federico II, Italy
Bedeschi is providing the turnkey design, engineering, construction, complete supply of materials, commissioning and starting up of equipment to the development of the 2640 MW South Brindisi ENEL power plant, Federico II.

South Brindisi is one of the biggest coal-fired power plants in the country. It is operated by ENEL Produzione S.p.A. The power plant will use coal sourced from Indonesia and South Africa.

The project, which was a response to protests by environmentalists and the local authorities, will aim to take the place of the current outdoor longitudinal coal storage at the power plant. This will involve the implementation of two new domes with a wooden covering structure and an environmental impact almost equal to zero. The dome’s dimensions will be as follows:

• A diameter of 150 m.
• A height of 45 m.
• A total stored volume of coal equal to 350,000 t.

The implementation of circular technology in the stacking and reclaiming operation will also see an increase in efficiency.

The contract issued with Bedeschi, which started in August 2011, includes the supply of all the mechanical components and the electrical and control systems for two STK R 35/2000 circular stackers and two PAL PRD 300/36+240/24 double arm slewing lateral portal reclaimers for coal handling at the power plant. These will be installed into the two new covered domes for the complete automation of stacking and reclaiming operation. The stackers have been designed for 3000 tph and the reclaimers have been designed for 1500 tph.

This project is unusual because the two machines will be equipped with state-of-the-art safety and environmental systems.

The project uses various new technologies. The machines will be equipped with a vacuum cleaning system for standard maintenance operations, a water spray system for dust suppression and de-dusting operations, an air compressed system and also, due to the highly restrictive classification of the hazardous area (ATEX 22.2), two fire fighting systems.

A gas fire fighting system will be located in the power and control cabins, while a high pressure water fire fighting system will be installed in the machine column to prevent and fight any fire that may occur on the heap surface of the stored coal or on the belt conveyors onboard the machines.

Conclusion
The case studies show the potential gains to be made by combining the latest available stacking and reclaiming technology for coal storage at power plants. The choice of the best machines to be selected depends on several factors including the type of coal handled and requirements for blending. Bedeschi's Technical Department is available to assist users and recommend the most appropriate technical and commercial solution.

This article was originally published in the November issue of World Coal. For more articles like this, sign up today for a free trial.

Written by Marco Bertorelle, Bedeschi S.p.A., Italy.

Edited by Jonathan Rowland

Read the article online at: https://www.worldcoal.com/handling/27012014/coal_storage_solutions_from_bedeschi_handling01/