Auma develops bus stop solution

German company Auma Riester GmbH has developed a fieldbus for connecting electrically automated values using loop redundancy so that system integrity can be maintained even if the bus is interrupted at one point.

The system, which uses conventional copper fieldbus cable, is capable of interconnecting 127 actuators – each up to 1200 m apart – providing a maximum loop circumference of nearly 154 km. System performance is increased by including a signal repeater in every actuator.

Auma fieldbus provides valve automation with long distance redundancy
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Data transfer across the fieldbus complies with the open Modbus protocol. An Auma Master Station SIMA, which is capable of administering loop redundancy, acts as the fieldbus master station.

Automatic voltage control for ESPs from Stock Equipment

A new digital electrostatic precipitator (ESP) controller has been launched by Stock Equipment. The AVC X-M is an automatic voltage controller based on a 32 bit microprocessor with a dedicated digital signal processor to enhance accuracy and stability and for advanced waveform analysis.

The use of high speed, high resolution digital sampling allows plant staff to diagnose ESP problems without the need for an oscilloscope. The speed and accuracy of the AVC X-M combined with the use of advanced control algorithms are intended to proved more intelligent reaction to sparks, allowing more power to be provided to the ESP more often.

The unit is designed to allow automatic fine tuning of the ESP during changes of fuel or process. It has Triple level circuit protection as well as standard features such as energy management, power-reduced rapping, back corona detection and background power settings.

Greener without recycling

A gas and dual-fuel burner from Hamworthy Peabody offers low emission levels without the need for recirculated flue gas (RFG). Eliminating the need for RFG, together with low burner draft loss, lowers overall energy consumption too, the manufacturers say. With a capacity of up to 20.5 MW, the Envirojet burner can be mounted onto a boiler front at virtually any angle while front air entry and monobloc assembly allows for reduced cost of installation, the company claims.

The burner is capable of operating with NOx emission levels of less than 30ppm when burning natural gas without RFG. RFG and water injection can be used to reduce emission levels further. The unit has the option of variable fan speed and is designed for quiet operation. It is compatible with both water tube and fire tube boilers.

GE 7H gas turbine heads West

The first 60 Hz 7H gas turbine from GE Energy’s Greenville, South Carolina plant has completed testing and is on the way to California. The unit, one of two planned for a 775 MW generating plant call Inland Empire, is capable of greater than 60 per cent thermal efficiency in the H-system combined cycle configuration according to the US company, making it the most efficient design so far produced.

The 316 t unit was transported from Greenville to the port of Charleston by rail where it joined a vessel for a six week voyage through the Panama Canal to Long Beach, California. From there it will be moved by road to the Inland Empire Energy Center in Romoland, near Riverside.

The gas fired combined cycle power plant is expected to begin operating in the summer of 2008. The project is being financed by GE which will own the plant. Calpine Power Services will manage plant construction and Calpine Energy Services will market the plant’s output. Calpine is expected eventually to purchase the power station and to become its sole owner and operator.

GE’s H system turbines employ steam cooling which enables higher turbine firing temperatures. First stage buckets and nozzles are made from single-crystal material to withstand the extreme conditions. Three 50 Hz 9H turbines were shipped to Japan in June while the first GE H-system, at Baglan Bay in the UK, has been in commercial service since 2003.

High capacity heat exchanger for power plant market

A heat exchange with a heat transfer area of up to 3.8 m2 per plate and capable of accommodating flow rates of more than 4500 m3 per hour has been developed by UK-based company APV. Called the APV Sirius, the heat exchanger can be provided in a variety of sizes, designs and plate patterns. It is aimed at the large power plant market as well as oil and gas processing facilities.

The APV Sirius heat exchanger stands tall
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The heat exchanger is available in titanium for seawater cooling and AISI316 for freshwater use. Plate thicknesses are 0.5 mm, 0.6 mm and 0.7 mm and the design temperature range is -35°C to 150°C. There is a specially designed hoist for handling tie bars and nut spanners and a ‘bubble lock’ plate locking system ensures correct plate pack alignment, the company claims. EasyClip gaskets are used to reduce service down time and spare part costs. The heat exchangers meet ASME and PED international standards.

Ceramic Fuel Cells moves a step closer to volume production

The Australian company Ceramic Fuel Cells has announced a new generation of fuel cells which it believes will be a major step towards commercialization. The units will be incorporated into micro-combined heat and power units for homes and small offices.

The new cells, with a power density of more than 400 mW/cm2, are over twice as powerful as the company’s current fuel cells. This higher power density will enable smaller fuel cell stacks to be built, making them easier to integrate into commercial appliances.

The new fuel cell stacks are designed to produce 1 kW of electricity with significantly less than 1 kW of heat. Each stack is composed of square ceramic fuel cells arranged in a ‘window-frame’ display and separated by metal interconnect plates. Other design improvements include a 50 per cent smaller steam generator, a 40 per cent smaller heat exchanger and a 75 per cent reduction in airflow through the system.

Acciona debuts 1.5 MW unit

Spanish company Acciona has launched a new AW-1500 wind turbine with an improved nacelle design by Navarrese sculptor Faustino Aizkorbe. The 1.5 MW machine is available with rotor diameters of 70 m, 77 m and 82 m and with tubular steel towers of 60 m and 80 m hub height. An 80 m concrete tower is also available and a 100 m concrete tower is expected to be certified shortly.

The main shaft of the new machine is mounted on a double frame to reduce load on the gearbox. It employs variable speed technology and has independent hydraulic pitch control for each blade. The unit’s asynchronous generator operates at 12 kV.

The sculpted nacelle of the new AW-1500 wind turbine
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The company, which has two manufacturing facilities in Spain and a third in China with a combined capacity to produce more than 1120 units each year, is also developing a 3 MW turbine based on the AW-1500. The new machine will be available with rotor diameters of 100 m, 109 m, and 116 m and with tower heights options of 100 m and 120 m.

In situ bearing repair keeps outage on schedule

When technicians at Verve Energy’s Kwinana power station in Western Australia discovered unexpected wear in a intermediate pressure (ip) steam turbine shaft bearing support during a nine-yearly outage they needed to find a means of repairing the damage.

The wear in the bearing support threatened to cause operational problems and reduce the bearing’s life expectancy. However engineers from Verve Energy and the outage contractor, Siemens UKG Alliance, found a solution; build up the affected area with weld and then remachine it in order to reproduce the original spherical surface. For this they enlisted the skills of Australian company Furmanite and its on-site machining expertize.

Technicians inspect the ip steam turbine at Verve Energy’s Kwinana plant
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The work by Furmanite, which took five days from initial inspection to completion, required construction of a precision assembly to carry out the remachining of the bearing. Following addition of the weld material, machining was carried out in incremental steps until it matched the original surface to within 0.03 mm. This speedy resolution of the problem allowed the outage at the six-unit 900 MW power plant to proceed on schedule.