Coal Bed Methane Oxygen Analyzers
Introduction
In recent years there has been a great demand by producers, processors, and distributors of natural gas to measure oxygen in natural gas produced from the coal bed deposits of North America.
The importance of oxygen measurement includes contamination control, product validation, and safety.
Teledyne is the acknowledged market leader for providing analysis systems to this market. The benefits of choosing a Teledyne system for this application are plentiful:
Teledyne has more field installations than any other manufacturer of similar systems
Teledyne is the only manufacturer of such analysis systems to have a field proven sensor, the A-2C, for natural gas streams. This sensor is produced in our factory with our ISO 9001 certified quality management system, providing the highest quality and reliability of this key component.
Despite the claims of other manufacturers, only Teledyne is able to provide a third party, NRTL (Nationally Recognized Testing Laboratory) approved system for Class 1, Div 1. (Visit our certification page for confirmation). Moreover, some manufacturers simply use approved junction boxes for alarm connections which does not equate validation by an authorized third party testing lab for demanding Class 1, Div 1 service.
Teledyne analyzers are available in a variety of configurations, and in many cases are custom engineered at no extra charge to minimize integration issues. Our experienced Engineering team is dedicated to excellence.
Finally, consider the Teledyne Advantage which is our superior customer service and support. A defective analyzer can cost thousands of dollars in lost revenue. Teledyne's customer service department is available 24 hours a day, 7 days a week.
The Pipeline Process
Natural gas is extracted from the depths of 3000 to 15,000 feet. During the initial years of exploration, the gas will be under 60 to 70 psig pressure which is sufficient for removal.
However, gas pressure drops over time and eventually the pressure equilibrates with ambient pressure requiring external motive force for further extraction.
Compressor Extraction
Two common modes of forced extraction are flooding and applying a vacuum using large capacity compressors. The compressor method is more common where the facility has only gas wells. When oil is also extracted, water coming out with the oil is separated and used for flooding the gas wells to compress and extract the gas.
When compressors are used, 8 to 32 gas wells are lateralized and pooled per compressor. Compressors are sometimes used even when the gas is under pressure where the well location is sub-optimal and extraction efficiency is poor.
Applying a vacuum to extract the gas creates the potential for atmospheric oxygen leaking into the pipeline / wellhead. The leakage can occur through the stuffing box on the plunger or through the gas transmission pipeline. Therefore to insure purity and safety, monitoring for oxygen contamination is essential.
The Oxygen Problem
According to industry professionals -
Oxygen at higher levels (1000 ppm or above) would pose a severe explosion hazard at the wellhead
Even at 100 ppm levels, oxygen can pose significant corrosion threats to the pipeline. With long distances of the pipeline buried underground, corrosion may cause gas leaks and contamination threats
On a commercial note, the value of the natural gas drops significantly if the sales gas has more than 50 ppm of oxygen
Oxygen Monitoring System Requirements
Consider: A power line may not always be available. Solar power is the main source with panels normally supplied as part of the flow computer unit (FCU)
Therefore: The analyzer may have to work at 12 VDC power or less
Consider: Telemetry is the main source of signal back to the SCADA. The telemetry system is supplied as part of FCU.
Therefore: The analyzer should seamlessly integrate with the FCU in use. Signals should be unaffected during wireless transmission
Consider: Field instruments are subjected to severe extremes in environmental conditions
Therefore: The system should endure the conditions of the great outdoors -- 24 hours a day, every day of the year.
Consider: Special radios are used in the field for communication with the control staff
Therefore: The system should be unaffected by strong radio frequency interference.
Teledyne has considered all these important factors as well
Teledyne's Solution
OT-3
The OT-3 is designed to accurately monitor the oxygen content in a wide variety of gases at the ppm level. The transmitter is equipped with two oxygen analysis ranges (0-100 and 0-1000 ppm) and is acceptable for operation in Class I, Division 2, Groups B, C, and D hazardous environments when used in conjunction with a non-incentive power source such as the Elsag Baily Total Flow System.
The OT-3 is designed to work with Total Flow model 6713, one of the predominant FCUs in the industry. Moreover, the system operates at as low as 9 VDC.
The heart of the OT-3 system is Teledyne's own Micro-fuel Cell oxygen sensor. This cell is a sealed electrochemical device which translates the amount of oxygen present in a sample into an electrical current. Since it is sealed, there is no electrolytes to change or electrodes to clean, and is therefore virtually maintenance free.
The OT-3 System is housed in a metal NEMA-4 case with the display visible through a clear Lexan window. For access to the Micro-fuel Cell and transmitter controls, the front door swings open.
Feature Overview
Two analysis ranges, user selectable, 0-100 and 0-1000 ppm
Designed to work with Total Flow model 6713, one of the predominant FCUs in the industry
Operates at as low as 9 VDC
High sensitivity (0.5% FS)
High accuracy (+/- 2% of full scale at constant temperature)
Insensitive to flow variations
Fast response and recovery
Long, life maintenance free Micro-fuel Cell sensor
Unaffected by reducing agents (HC's, CO, SO2, etc.)
Easy to calibrate, no zero gas required
Rugged NEMA-4 bulkhead mount enclosure
Stainless steel sample system (nylon cell holder)
H2S scrubber
InstaTrans-XD
The InstaTrans-XD is a two-wire, loop-powered 4-20 mA oxygen transmitter packaged within a weather tight NEMA-4 housing. The product was named for its built-in level of flexibility, as it can instantly transform from ppm to percent (or vice-versa) by changing out the Teledyne sensor and resetting the range scale of the unit to ppm or percent via the function keypad. No other electrical or resistor changes are required.
The InstaTrans-XD has six user selectable ranges from 0-10 ppm to 0-25%. In addition, depending on the corrosive nature of the sample, the InstaTrans-XD can be supplied with either stainless steel or nylon wetted parts.
Unlike the competition, Teledyne's transmitter offers one key feature invaluable to the user a built-in meter. Through visual feedback, the user confirms correct operation of the InstaTrans-XD whether it be a range change or conducting a span calibration. The meter incorporates various readouts to clearly and continuously show:
Insta Trace Inside
For the InstaTrans-XD, Teledyne patented a novel method of improving the time it takes to obtain meaningful results (below 10 ppm O2) when changing from an expired cell to a new one. Historically, the recovery period required when changing out trace Micro-fuel Cells was from 12 to 24 hours. Under Teledyne's newly patented sensing technology, INSTA TRACEª, users can obtain meaningful trace oxygen results in just a few minutes.
Intrinsically Safe Design
The InstaTrans-XD can be used in a general purpose, non-hazardous environment or a hazardous area. When used in Division 1 or equivalent hazardous / classified locations, the InstaTrans-XD must be installed in conjunction with optional intrinsic safety barriers. The InstaTrans-XD is designed as intrinsically safe for use in Class I, II, Division 1, Groups A, B, C, D, E, F & G hazardous areas or EExiaIICT4 (60°C). The InstaTrans-XD is self-certified by Teledyne as suitable for Class I, Division 2 areas without the use of I/S barriers utilizing specific installation guidelines.
Download a PDF data sheet of the InstaTrans-XD here.
