#202 - GE 7216 V2.2 H2 Analyzer available at Nova

Over the years, we have had many requests for an analyzer system called GE 7216 V2.1 or V2.2. We used to manufacture this product for GE. It was specifically for use as a stator leak detector on large electric generators. In time, some of the components and technologies used in this analyzer were discontinued and subsequently updated.

We have also noticed that the functionality of some of these systems has been impaired by moisture ingress over the years. On most sites, the moisture removal systems prior to the H2 detector have been designed and installed by the original generator provider. If these fail, moisture can enter the H2 detector and ruin it.

Even though the GE 7216 V2 is no longer available to electric power providers, we do have a couple of options to allow you to proceed with a solution.

Replacement detector assembly – If all of the other components on the system are functioning properly, and an updated detector is all that is needed, we may be able to provide a heated box assembly with the updated detector inside. This option is not available in every case, but may be worth inquiring about.

Replacement gas analyzer – The GE 7216 V2 product was in production quite a number of years ago. Many of the installations are getting old or have been contaminated with water, and require replacement instead of repair. The Models 430VN4 and 430QN4 Continuous Hydrogen Monitor are available for this purpose.

The various components are now protected inside a common NEMA 4 wall-mount cabinet. The H2 reading is displayed locally on the analyzer cabinet, and is also sent to an analog 4-20mA output. As an option, we can make this an isolated or non-isolated output. We can also provide a hydrogen alarm with indicator light and relay contact.

The slight difference in model numbers designates the design of moisture removal system. Some installations have a supply in instrument air already connected to the old 7216 module. The new 430VN4 can also utilize this air supply. If there is no instrument air available, the model 430QN4 can be used instead.

If you have a 7216 and are experiencing age- or moisture-related problems, we can undoubtedly assist you. Contact us by e-mail. Be sure to state your 4-digit serial number and full model number.

1-800-295-3771

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#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.

1-800-295-3771

sales at nova-gas dot com

websales at nova-gas dot com

http://www.nova-gas.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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#160 - Improving the Safety of Hydrogen Analysis - Nova Model 436 for Generator Monitoring

Many large power generators use hydrogen gas as a coolant. Hydrogen has low density and very good thermal conductivity. It can carry away the heat produced in a generator and thus allow the generator to operate at a higher power output.

The Nova Model 436 is an excellent choice for continuous monitoring of the hydrogen atmosphere in a generator. It offers the following analysis ranges:

Range 1: 0-100% Hydrogen in Air

Range 2: 0-100% Hydrogen in CO2

Range 3: 0-100% Air in CO2

This model is similar to the portable Model 380 mentioned in this post. When a generator shutdown is scheduled, it is recommended that the continuous analyzer is used to monitor the purge process, while a portable analyzer is also connected and used as a back-up monitor.

We have been asked recently by some power companies to consider offering an additional interesting feature to the Nova Model 436.

In some cases, an unsafe condition has developed when the continuous H2 purity analyzer has been accidentally switched to the wrong range and left to operate that way. The analyzer will now be looking for an incorrect combination of gases and will not report a reliable result. Because H2 purity is an important parameter to monitor during normal generator operation, the analyzer should remain set to the correct range for reliable results.

Would this feature be of interest to you? 

To ensure that the purity range is activated at all times during normal generator operation, an explosion-proof lock-enabled switch can be provided. The purity range would be always locked on, and only a key could disable it and enable the purge ranges. The key would stay in the slot during purge, and only be removable when the purity range is selected again. Perhaps the key would be kept in the supervisor’s office when not in use.

If this is of interest to you, contact Nova for details.

1-800-295-3771

sales at nova-gas dot com

websales at nova-gas dot com

http://www.nova-gas.com/

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#147 - Hydrogen - Nova Model 380 for Generator Monitoring

Many large power generators use hydrogen gas as a coolant. Hydrogen has low density and very good thermal conductivity. It can carry away the heat produced in a generator and therefore allow the generator to operate at a higher power output.

The Nova Model 380 is an excellent choice for monitoring the hydrogen atmosphere in a generator. It offers the following analysis ranges: 

• Range 1: 0-100% Hydrogen in Air
• Range 2: 0-100% Hydrogen in CO2
• Range 3: 0-100% Air in CO2

The ranges mentioned above are designed to allow monitoring of the purge procedure that is implemented during a generator shutdown. However, not all purge procedures are exactly the same for each generator. We have been asked recently by some power companies to consider offering some additional capabilities to the Nova Model 380.

Would these features be of interest to you?

- We can produce a variation of Model 380 that allows it to be used on generators that are purged with Nitrogen (N2) instead of CO2.

- We can also produce a Model 380 that is set up for Argon (Ar) instead of CO2.

- We can also add dew point analysis and hydrogen pressure indication to Model 380.

If any of these options are of interest to you, contact us here about these options.

For information on Nova gas analyzer systems, give Mike or Dave at Nova a call, or send us an e-mail.

1-800-295-3771

sales at nova-gas dot com

websales at nova-gas dot com

http://www.nova-gas.com/

https://twitter.com/NOVAGAS

http://www.linkedin.com/company/nova-analytical-systems-inc-

http://www.tenovagroup.com/

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