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Thursday, November 6, 2014

#196 - Nova Analyzers from the Field – Episode 8

Frequently, we get requests from power plants to offer a solution for hydrogen analysis. We mentioned before in this post and on the website here, that the power industry often uses hydrogen as a coolant for their electric generators. It is quite important in this application to maintain a high-purity of hydrogen. Reduction in purity can reduce cooling effectiveness and possibly allow an explosion potential to develop in the generator.

A common scenario involves older generators that still have the original hydrogen detector. The old H2 detector may be failing and a new instrument using modern technology and components is required.

Old GE Hydrogen panel.

We were sent these pictures from a large power provider in North America. The basic scope of this project was to replace the old OEM hydrogen purity analyzer which was manufactured by GE circa 1950’s. It measured the generator cooling gas, but in recent years, the spare parts and replacement sensors were getting too costly.

From the customer’s inspection of the old equipment, the old electronics consisted of wire wound resistors and transistors which had been obsolete for years. According to them, it was ‘state of the ark’ technology, as opposed to ‘state of the art’. The actual H2 purity measurement apparently used 100 ohm nickel RTD’s (resistance temperature detectors). Gas temperature and dew point of the gas are also usually measured in this application.

The upgrade project required a replacement hydrogen detector. The Nova Model 436 was the instrument of choice for this plant. This was probably because they had excellent success and performance from the portable 380 instrument that is used for the same application.

The generator has a fan on it to circulate the gas. One of the hurdles on this project was to get enough differential across the new analyzer sample cell to avoid having to vent the atmosphere gas out of the generator. They were able to configure the generator gas flow and sample input/output points to produce 0.6 LPM flow out of the generator, through the analyzer, and back into the generator.*

New Nova Hydrogen panel. Model 436N7N4 - The Control Cabinet
is on the left. The Detector Cabinet is on the right.

Recent performance evaluations at the plant indicate that the NOVA appears to have enough flow to measure correctly. The temperatures are measured with Rosemount Smart Temperature Transmitters. Everything seems to working very well now and they are very pleased with the results of their new panel.

For information on these and other gas analyzer systems, give Mike or Dave at Nova a call, or send us an e-mail.
sales at nova-gas dot com
websales at nova-gas dot com

* Nova analyzers usually operate best with a flow of 1 LPM. However, in this case, the flow of 0.6 LPM will be sufficient as long as they calibrate at that flow rate.


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