EATON TN06 520-1005 MTL Gas Analysers and Systems User Guide
- June 12, 2024
- EATON
Table of Contents
EATON TN06 520-1005 MTL Gas Analysers and Systems
Product Information
- The MTL gas analyzers and systems are designed for monitoring and controlling de-oxo plants. These plants are used to remove the final traces of oxygen from low-grade nitrogen produced by pressure swing absorption plants (PSA) and membrane nitrogen generators. The MTL gas analyzers use a zirconia oxygen sensor to measure oxygen concentration in the nitrogen gas, allowing precise control of hydrogen addition to react with the oxygen.
- The zirconia oxygen sensors produced by Eaton have unique attributes that make them ideal for this application. They can measure oxygen concentrations ranging from 1 down to 10-23 atmospheres and provide a rapid response rate measured in fractions of a second. The sensors work similarly to pH electrodes when measuring acidity, allowing them to monitor the neutralization of oxygen with hydrogen in a de-oxo plant.
- Using the MTL gas analyzers eliminates the need for expensive precision analyzers, flow meters, computers, and mass flow control valves, which are required in traditional monitoring methods. Additionally, the use of zirconia oxygen sensors reduces the amountof hydrogen present in the final product, offering an alternative approach to de-oxo plant monitoring and control.
Product Usage Instructions
To monitor and control a de-oxo plant using the MTL gas analyzers, follow these steps:
- Ensure that the de-oxo plant is properly installed and connected to the nitrogen generator or membrane nitrogen generator.
- Connect the MTL zirconia oxygen analyzer to the de-oxo plant according to the provided diagram (Figure 1).
- Power on the MTL zirconia oxygen analyzer and wait for it to initialize.
- Configure the analyzer settings, including the desired oxygen concentration range and response rate.
- Start the nitrogen production process in the PSA or membrane nitrogen generator.
- Monitor the oxygen concentration in the nitrogen gas using the MTL zirconia oxygen analyzer.
- Adjust the hydrogen flow rate to react with the oxygen based on the readings from the analyzer.
- Continue monitoring the oxygen concentration and adjusting the hydrogen flow rate as necessary to maintain the desired oxygen content in the product.
- If required, pass the gas through a dryer before using it for technical or safety reasons.
For further assistance or troubleshooting, refer to the complete user manual or contact Eaton Electric Limited at the provided contact details.
De-Oxo Plant Monitoring and Control
- Recent years have seen a revolution in the production of nitrogen, particularly of the so called low grade variety containing 0.1 to 1% oxygen.
- Whereas twenty years ago nitrogen was produced almost exclusively by the distillation of liquefied air, today pressure swing absorption plants (PSA) and membrane nitrogen generators are being used in growing numbers.
- These noncryogenic plants selectively remove oxygen from air to produce nitrogen (mainly) with a typical oxygen content of between 0.1 and 1%. Both systems, particularly PSA, can be designed to produce a much lower oxygen content, but it is frequently uneconomic to do so. As an alternative, de-oxo plants can be used to remove the final traces of oxygen from the products of these plants.
- De-oxo plants work by adding hydrogen to the low-grade nitrogen and react the resultant mixture by passing it through a column of catalytically active material. The hydrogen reacts with the residual oxygen to form water. The following chemical equation describes the reaction.
- 2H2 + O2 + N2 = 2H2O + N2
- If necessary, the gas can then be passed through a dryer. For either technical or safety reasons many processes that use the gas produced by this system cannot tolerate any excess hydrogen in the product.
- The problem, therefore, is to add just sufficient hydrogen to react with the oxygen.
- One of the most common approaches to the problem has been to monitor the oxygen concentration in the product from the nitrogen generator and its flow rate to the de-oxo reactor.
- These figures are used by a microprocessor system to compute the flow rate of hydrogen required to react with oxygen.
The required flow rate is then set by means of an expensive mass-flow valve
placed in the hydrogen supply line. As a safety check, the end products are
monitored by a hydrogen analyzer whose resolution is typically ±50ppm at best.
The method works but has two major disadvantages.
- It is expensive; requiring precision analyzers, flow meters, computers and mass flow control valves.
- It results in the product containing noticeable amounts of hydrogen.
An alternative approach is to use an oxygen analyzer produced by Eaton based on an MTL zirconia oxygen sensor
Eaton Electric Limited, Great Marlings, Butterfield, Luton Beds, LU2 8DL, UK.
Tel : + 44 (0)1582 723633
Fax : + 44 (0)1582 422283
E-mail: [email protected]
www.mtl-inst.com
© 2016 Eaton
All Rights Reserved Publication No. TN06 520-1005 Rev 3 October 2016
De-Oxo Plant Monitoring and Control
October 2016
MTL Zirconia oxygen sensors have a number of unique attributes two of which
make them ideal for this application. Firstly, they can measure oxygen in
concentrations ranging from 1 down to 10-23 atmospheres; secondly, they can do
this with a response rate measured in fractions of a second. They measure
oxygen concentration in an analogous way to pH electrodes when measuring
acidity.
In a way similar to a pH electrode being used to monitor the neutralising of
an acid by an alkali, a zirconia oxygen sensor can be used to monitor a
“neutralisation” of oxygen with hydrogen
The graph in Figure 2 shows the classical neutralization curve for such a
process. The ‘neutralization’ point is where the reactants are in exactly the
correct proportions to produce no excess of either. This is normally referred
to as the ‘stoichiometric’ point.
At this point the concentrations of oxygen and hydrogen are due entirely to
the dissociation of the water produced by the reaction and are in the order of
parts per billion.
Fig. 1 (overleaf) shows the general arrangement for monitoring and controlling
a de-oxo plant using a MTL zirconia oxygen analyser.
Using this approach allows a lower-cost conventional controller and control
valve to be used as well as making the system fundamentally simpler. If
required, an additional hydrogen analyser/monitor can be incorporated to
monitor for a fault situation; e.g. the de-oxo reactor failing. Eaton can
supply an oxygen analyser with this additional monitor incorporated.
Note : The MTL G1010 oxygen analyser (H-type cell) and MTL K1550 hydrogen
analysers are used in this type of application.
Eaton Electric Limited, Great Marlings, Butterfield, Luton Beds, LU2 8DL, UK.
Tel: + 44 (0)1582 435600
Fax : + 44 (0)1582 422283
www.mtl-inst.com
E-mail: [email protected]
© 2016 Eaton
All Rights Reserved Publication No. TN06 520-1005 Rev 3 191016 October 2016
EUROPE (EMEA): +44 (0)1582 723633
[email protected]
THE AMERICAS: +1 800 835 7075 [email protected]
ASIA-PACIFIC: +65 6 645 9888
[email protected]
The given data is only intended as a product description and should not be
regarded as a legal warranty of properties or guarantee. In the interest of
further technical developments, we reserve the right to make design changes
October 2016 TN06 520-1005 Rev 3