Equipment Roundup

India’s MSEB overcomes duct difficulties at Chandrapur

In May 2003, India’s Maharashtra State Electricity Board (MSEB) awarded a contract for the replacement of the flue gas duct at one of its power plants to Alstom Power Service India. Just five months later, the plant’s boiler was back operating at full load.

The contract for the work at the Chandrapur Super Thermal power station Units 5 and 6 was awarded to Alstom against BHEL, which installed the original equipment in 1991/2. The scope of the contract included the design, engineering, supply, civil work, installation, thermal insulation, uniform gas distribution and commissioning of the system.

MSEB awarded a contract for the replacement of the flue gas duct at the Chandrapur power plant to Alstom Power Service India in May 2003
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After a few years of operation, MSEB observed excessive erosion in the two units’ flue gas ducts, which were designed for a very high gas velocity. Furthermore, due to a leakage in the system, the gas velocity went as high as 22 m/s. This not only resulted in a loss of power generation but also forced MSEB to carry out a huge patchwork in duct that was just a temporary stopgap arrangement to minimize leakage. The situation caused the utility a huge financial loss.

Alstom Power Service India worked out a technical solution and executed the work on Unit 5 in just five months ” three months faster than was offered by BHEL. To save time, detailed manufacturing drawings and manufacturing of duct were done on site. This also ensured dimensional accuracy and quality, and eliminated any transit risk.

The Unit 5 boiler was operating at full load in September 2003 with the following achievements:

  • The gas flow distribution 8 nos. ESP pass was achieved within a range of +2.3 per cent and -3.3 per cent, compared to a guaranteed range of à‚±10 per cent.
  • The pressure drop across the ductwork was reduced. As a result, MSEB is now operating the boiler at 100 per cent load (500 MW) instead of 450 MW.
  • All the ID fans are now running with approximately 45 per cent damper opening instead of 100 per cent damper opening before. This has resulted in a substantial power saving.

ESB looks for quality

Systems designed and built by Christ-Kennicott Water Technology will perform the crucial task of maintaining water quality for boilers and steam turbines at two new ESB power stations in the Republic of Ireland.

The company is incorporating its Conesep condensate polishing technology, renowned internationally in power generation, as part of complete water treatment systems for the 150 MWe West Offaly station in Shannonbridge, County Offaly, and the 100 MWe Lough Ree station in Lanesboro County. The orders were placed by Foster Wheeler Energia Oy, which is constructing the two peat-fired power plants.

Christ-Kennicott is supplying water treatment systems to two peat fired power plants in Ireland
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Both are turnkey projects for Christ-Kennicott. At Lanesboro, boiler make-up will be supplied from a local bore hole and treated by an ion exchange plant delivering 30 m3/h.

In contrast, Shannonbridge will treat water from the river Shannon for boiler make-up.

Gear units step up production

A new conveyor system designed to increase production at UK Coal’s Daw Mill Colliery by up to 50 per cent is using Series G gear units supplied by David Brown, a Textron Power Transmission company.

The new conveyor, designed and built by Continental Conveyors, serves the latest coal face to be worked in the Warwickshire Thick seam, which produces fuel for power stations in the UK. The conveyor allows up to 1200 t/h to be brought to the surface via three main conveyors sited in the underground-to-surface drift system. Previously, the Daw Mill drift conveyor system was transporting 800 t/h of coal.

The new conveyor system at UK Coal’s Daw Mill Colliery employs David Brown’s Series G medium/heavy duty gear units
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The new system has a coal carrying speed of 4.6 m/s. It employs five new David Brown Series G gear units gearboxes rated at 1317 hp with an input speed to the gearbox of 1500 r/min and a reduction ratio of 20.594:1. They are linked by solid couplings to Breuer 600 hp variable speed motors.

Alstom Power Service India executed the work on Unit 5 in just five months
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The Series G units were specified for their robustness and ease of maintenance in service. An additional factor was David Brown’s ability to design and supply a sixth unit to be used in either a right handed or left handed mode, providing UK Coal with a single unit to serve as a versatile spare.

Arkansas replacement

SGT Ltd., a joint venture between Washington Group International and Framatome ANP, has received a contract to provide engineering and construction services for the replacement of steam generators and a reactor vessel closure head at Entergy’s Arkansas Nuclear One unit 1 plant in the USA.

The SGT work scope includes heavy haul of the components at the plant site, creating a temporary opening in the reactor containment building, and closing the opening once the retired equipment is removed and the replacement components are installed. The components will be supplied by Framatome ANP and replaced during a scheduled outage at the plant.

New drive for wind turbines

ABB has launched a new drive for wind turbines which combines advanced technology with modular construction to provide a flexible solution for the wind energy market. It can be used with both doubly fed asynchronous and full size synchronous generators, as well as with the latest permanent magnet generators.

The new ABB 2 MW doubly fed drive measures only 1.6 x 1.8 x 0.6 m, and so can easily be accommodated in the nacelle
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The new drive is available with output ratings in the range 1-5 MW. Compact size was a main consideration during the design process, and the drives are around half the size of previous units. The 2 MW doubly fed drive, for example, measures only 1.6 x 1.8 x 0.6 m, which means that it can be easily accommodated in the nacelle. As a result, the drive can be factory installed by the turbine manufacturer, avoiding costly and time-consuming work on site. Scalability means that the same modules can be used in designs for different types of turbine and makes for easier maintenance and servicing.

Direct Torque Control (DTC) is used to provide fast and accurate control of both speed and torque without the need for pulse encoder feedback from the shaft. DTC offers a number of benefits, including robust operating characteristics, high availability and reliability, and high quality output with low harmonics. Through the use of DTC, the drives maintain good output quality over wind conditions varying from light to gusting, and they are also tolerant of fluctuations in the power network.

Advanced coal control solution

The USA’s Siemens Westinghouse has announced the launch of Power Accuracy Control Solutions (PACS), an innovative suite of advanced process control solutions for coal fired power plants. PACS was developed to address a wide range of power plant operational issues and has been proven in the global power markets.

The PACS technology was recently applied to the 780 MW supercritical coal unit at the Pennsylvania Power & Light Brunner Island Steam Electric Station in northeastern USA. This unit could not pass its load change accuracy test, which is required in order to sell premium services into the local power market. The plant had been operating in the conventional turbine follow mode, which yielded the most stable unit operation but not the precision control required during load transitions. The plant’s engineers tried a number of conventional tuning procedures, but were not able to achieve acceptable results.

Siemens Westinghouse analysed the process data and the existing plant documentation. The analysis defined new control strategies which were implemented during a recent outage using the existing plant Distributed Control System (DCS). Installation took three days, plus one day for acceptance testing. The unit performed well and passed all tests, which allowed the plant to begin earning additional revenue from selling power into the local market.

New flammable gas sensor

Zellweger Analytics announces its new Sensepoint flammable gas detector ” the Sensepoint High Temperature sensor ” designed for use in high temperature areas such as gas turbines. Certified for use in environments up to 150à‚°C, Sensepoint High Temperature offers a cost-effective, reliable and ATEX-compliant solution for flammable gas detection.

As well as being ATEX-approved in its own right, the Sensepoint High Temperature sensor enables gas turbine manufacturers to adhere to the ATEX directive of 1st July 2003 via a method of ‘dilution ventilation’. This method, which has been agreed by the European Commission and the Association of European Manufacturers of Industrial Gas Turbines, requires additional detectors to be placed at specific points in the turbine installation where potential risk has been identified.

As a result, Zellweger Analytics expects increased demand for ATEX-compliant sensors such as the Sensepoint High Temperature sensor, which will be an integral part of gas-fired turbines.

The Sensepoint High Temperature sensor from Zellweger Analytics offers a cost-effective, reliable solution for flammable gas detection
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Sensepoint High Temperature uses Zellweger Analytics’ proven Sieger catalytic bead technology. A world-leader in the manufacture of this technology, the company is uniquely able to ‘match’ bead pairs for highly stable operation across a wide temperature range. As a result, Sensepoint High Temperature features alarm trip points which can be set as low as five per cent of the lower exposure limit (LEL), and has a choice of measuring ranges from 0-20 per cent LEL to 0-100 per cent LEL.

The Sensepoint High Temperature sensor from Zellweger Analytics offers a cost-effective, reliable solution for flammable gas detection

A low cost, disposable sensor, Sensepoint High Temperature has a typical operating life of more than five years and a low power consumption of just 0.7 W, making it a highly cost-effective choice for new build and end user retrofits.

Sensepoint High Temperature has a robust, ATEX-approved stainless steel housing and a wide range of optional accessories including weather protection assemblies, flow housings, field transmitters and bridge to analog signal converters.

Electromagnetic solution

Link Microtek has announced the launch of its new Narda ELT-400 low-frequency radiation safety meter, which has been designed to enable quick and easy measurement of ELF (extremely low frequency) magnetic fields within the electricity supply industry.

The new ELF radiation safety meter allows quick and easy measurement of low frequency magnetic fields
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With the European Union pressing hard for a Physical Agents directive to cover electromagnetic fields, it is likely that plant managers and health and safety officer will soon have to address the issue of ELF radiation. The ELT-400 provides an easy means of helping employers to meet the proposed directive’s requirement of assessing the risk to workers.

Covering the frequency range 1 Hz to 400 kHz, the meter features an integrated ‘shaped time domain’ function that allows simple measurement of the complex waveforms commonly encountered in the electricity supply industry due to the presence of multiple field sources or different frequencies.

At the touch of a single key, the ELT-400 automatically evaluates all the different EFL field sources and displays the reading as a percentage of the ICNIRP international safety guideline.

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