Emerson Process Management has introduced a special configuration of the Rosemount® Analytical CAT 100 continuous gas analyzer transmitter to meet all of the measurement requirements for hydrogen cooled turbine generators in electrical power plants.
The on-line thermal conductivity TCD analyzer is typically set up with three measuring ranges. The first and primary range (80-100% H2) is to monitor the hydrogen purity during normal operation; the second (0-100% H2) and third (0-100% CO2) measuring ranges allow safe opening of the turbines for maintenance.
On-line gas analysis is used to maintain a high concentration of hydrogen coolant to ensure cooling efficiency and maintain safe conditions. During normal operation, the hydrogen purity is monitored in an 80 to 100% H2 range (with air as background gas) to expose air leaks or hydrogen supply problems.
Keeping the hydrogen as pure as possible is critical for the efficient operation of a turbine. Every 2% reduction in the purity of the hydrogen coolant increases windage losses in the turbine and the cost of running an 800-megawatt generator is increased by up to US$1,000 a day. Contaminants in the hydrogen can also be very dangerous and air is the most common impurity due to leaks.
When the oxygen in the air is mixed with hydrogen, this can create an explosive condition. However, hydrogen does not support combustion in a nearly pure state (>90%) with the balance of air. By using the Rosemount Analytical CAT 100 continuous gas analyzer transmitter to constantly monitor the hydrogen purity, any potentially hazardous condition can be avoided, enhancing safety and maximizing efficiency and profitability.
When the turbine needs to be opened for maintenance, the hydrogen is first replaced with inert CO2 and this process is tracked with the second measuring range in the analyzer, 0-100% H2 (with CO2 as background gas). Once all of the hydrogen is removed, air is injected to displace the CO2 and this is tracked with the third measuring range 0-100% CO2 (with air as background gas). When all of the CO2 has been replaced with breathing air, it is safe to open the turbine. To restart the turbine, this process is reversed.
By accurately determining when each purge cycle is complete, the Rosemount Analytical CAT 100 continuous gas analyzer transmitter minimizes down time. Plant safety is enhanced by ensuring that the right conditions exist before personnel can open the turbine for maintenance.
About Emerson Process Management
Emerson Process Management (www.EmersonProcess.com), an Emerson business, is a leader in helping businesses automate their production, processing and distribution in the chemical, oil and gas, refining, pulp and paper, power, food and beverage, and other industries. A division of Emerson, Rosemount Analytical (www.EmersonProcess.com/proanalytic) includes a gas division is a leading supplier of on-line gas analyzers and systems for process, environmental and laboratory analysis applications. The best-in-class technology and expertise of Rosemount Analytical plays a key role in the Emerson mission of combining superior products and technology with industry-specific engineering, consulting, project management and maintenance services. Emerson brands include PlantWeb®, Fisher®, Micro Motion®, Rosemount®, Mobrey®, Daniel®, Bristol®, DeltaV(TM), Ovation®, and AMS(TM) Suite.
Emerson is a global leader in bringing technology and engineering together to provide innovative solutions to customers through its network power, process management, industrial automation, climate technologies, and appliance and tools businesses. Sales in fiscal 2005 were $17.3 billion.
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