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Fluorescence Quenching Eclipses Conventional O2 Measurements in Natural Gas Pipelines

Jennifer Soto — Wed, 03 Feb 2010 22:00:00 GMT

For as long as anyone can remember, Oxygen (O₂) has been a problem in natural gas pipelines, especially when high levels of H₂S are present.

Measurement of O₂ has always come with its own set of issues: maintenance costs, inaccuracies, and reliability. But all that is changing with the introduction of a new technology…Fluorescent Quenching.

Based on a proven technology in the bio-tech world, it uses a sensor (optical probe) that contains an indicator dye sensitive to O₂. The dye is optically excited by an LED light source. The fluorescence emission of the indicator dye decays at a known rate, but if oxygen is present an energy transfer occurs and “quenches” the fluorescence, hence the name, Fluorescent Quenching.

Advantages over traditional measurement include greater accuracy, much faster response, simplified calibration, and virtually no maintenance. There is also no need for a scrubber and the net result is lower overall operating costs.

The sensor is not affected by even high levels of H₂S and there is no cross sensitivity to contaminants or other gases found in natural gas.

Larry Ewing, the owner of Ewing Energy Consulting of Tulsa, Oklahoma, is an expert in gas quality measurement technology. He see’s a wide range of potential applications in natural gas pipelines for Fluorescent Quenching. “It is ideal technology for any area that has H₂S concentration such as sour gas monitoring, production areas, and pumping stations.”

SpectraSensors of Houston, Texas, recently introduced the OXY4400 optical oxygen analyzer for natural gas pipelines using this technology. SpectraSensors has pioneered the use of optical analyzers with its Tunable Diode Laser units that are used world-wide in the industrial process and environmental monitoring markets.

The OXY4400 oxygen analyzer is a compact, stand-alone, one-channel meter with LCD display and data logger. The unit uses a light source (LED), an optical sensor probe and a photo detector. Pulsed light from the LED is sent down a fiber optic cable to the sensor probe (optode) where the energy from the light is absorbed by an indicator dye. The light (fluorescence emission) is sent back through the cable to the photo detector, where it is converted to an electrical signal that can be read.

The amount of “quenching” is determined by the amount of O₂ in the stream. The result is an exact and almost instant measurement down to 0.5 ppm.

Accuracy

Conventional membrane sensors (Clark Cells and Galvanic Cells) can be destroyed by high levels of hydrogen sulfide in the stream. For this reason, they require a scrubber to absorb the H₂S. But when the scrubber becomes saturated the sensor loses it accuracy. In addition, traditional sensors use an electrolyte solution that is “self-consuming” caused by an electrochemical reaction to the oxygen concentration. But that consumption degrades the sensor (similar to a battery) over time forcing users to perform constant calibration. Once these trace oxygen sensors are exposed to high levels of O₂ it can shorten the life or destroy the sensor which must be purged and that can take a long time.

All of this adds up to high maintenance costs and replacement parts to keep membrane sensors accurate.

Fluorescent Quenching offers new levels of accuracy. It does not consume O₂ and needs no scrubber, in fact, it reads the O₂ without being affected by the hydrocarbons or sulfur content. Optical response time is measured in seconds, not minutes.

Since there are no moving parts or electrolytes, there is no need for constant calibration once it is installed. The optical sensor is also unaffected by EMI, shock, or vibration.

Cost Comparison

Initial costs of the OXY4400 are higher than the cost of a traditional system. But the total cost of ownership over the first year is much less than a membrane system. The difference comes from the elimination of constant maintenance and replacement parts for Galvanic cell or Clark cell units. In addition, the cost savings of the optical measurement increases over the lifetime of the instrument.

“It’s a ten-fold savings in cost of ownership compared to membrane technology,” adds Ewing, “and the reliability is much higher. Just think of the late night maintenance calls when an O₂ spike sets off an alarm. Membranes take hours to recover, the optical sensor recovers immediately. There is no need for a maintenance operator to stay on task for hours testing for a gas that isn’t there just because his antiquated sensor has not recovered yet to give him an accurate reading.”

Sam Miller of SpectraSensors sees a host of applications for the OXY4400. “This technology transforms oxygen measurement in the natural gas industry due to its long-term stability. This is especially important for remote locations.”

3-Feb-10 4:00 PM

Naizak and SpectraSensors sign MOU to Manufacture TDL Gas Analyser

Jennifer Soto — Thu, 27 Aug 2009 16:00:00 GMT

Naizak Global Engineering Systems and SpectraSensors, Inc of USA signed a Memorandum of Understanding to develop and manufacture the TDL (Tunable Diode Laser) gas analyzers for the Saudi Arabian and the GCC market.

The collective agreement was signed recently in Bahrain between Khalid Al Abdulkarim, President of Naizak, and George Balogh, CEO of SpectraSensors.

SpectraSensors is the leading global provider of laser-based process instrumentation. Naizak is a customer-driven, local services organization with a deliberate policy to invest in people of high caliber and specialization. A large part of that investment is in training nationals and allowing them to participate in our economy.

“The introduction of the TDL gas analyzers in Saudi Arabia and in the GCC through this partnership will boost the productivity and efficiency of the region’s oil and gas sectors,” Abdulkarim said after signing the agreement.

“We are pleased and delighted with our collaboration with Naizak, and our company looks forward to be able to provide the needs of the region’s hydrocarbon industry,” Balogh said.

Under the agreement, Naizak will manufacture and develop the product. The partnership will also undertake integration capability to qualify the approval of SpectraSensors products as Saudi Arabian manufactured products in order to gain market preference and better provide the needs and requirements of the customers.

The manufacture products will be marketing by Naizak to customers in Saudi Arabia, and in GCC through Naizak’s regional offices. SpectraSensors has assigned an official representative to assist Naizak permanently in Saudi Arabia. He will also support the development of the TDL marketing in the region.

SpectraSensors has proven solutions for various industrial sectors, such as natural gas, refinery, gas processing/LNG, petrochemicals, chemical and atmospheric weather measurements. The company has a portfolio of patents including 14 issued, 36 pending and licenses for an additional six technology and product patents.

SpectraSensors uses TDLs in conjunction with Absorption Spectroscopy in an array of products including: Ambient Air Monitoring Analyzers, Moisture Analyzers (Hygrometers), Dew Point Analyzers, Hydrogen Sulfide Analyzers, and Gas Analyzers for Natural Gas Pipelines and Processors, Petrochemical Refineries and Chemical companies.

SpectraSensors’ Gas Analyzers measure Moisture (H2O), Carbon Dioxide (CO2), Hydrogen Sulfide (H2S), Hydrogen Chloride (HCl), Mehtane (CH4), Ammonia (NH3) Ethylene Oxide (ETO) and for various applications.

The agreement provides the development of local manufacturing, sales and services and TDL Technology. More products are due for release.

Saeed Saad Al-Shahrani, Naizak General Manager of the Instrumentation & Control Division, said the development and production of the TDL products will be undertaken in three phases. As General Manager of the Instrumentation & Control Division, Al-Shahrani oversees and manages four divisions, namely sales, services, process/analytical, and ISG services and calibration.

“The TDL products are very environment friendly and enable the energy and petrochemical industries to get cleaner; they are designed specifically to improve process efficiency in refineries and chemical plants.” Al-Shahrani said. He said the immediate beneficiaries of the TDL products are the oil and petrochemical companies in the region, including Saudi Aramco and SABIC.

The TDL products are the most effective means of reducing environmental impacts from energy and chemical production by giving the accurate gas analysis. Improved process efficiency delivered by the TDL products enables lower maintenance costs, more accurate measurements, faster response times and more economic value with fewer materials and waste, according to Al-Shahrani.

Using tunable diode laser (TDL) technology that has been proven in the harshest real-world proven in SpectraSensors’ solutions successfully measure and monitor gas and petrochemical concentrations in a variety of applications such as environmental, energy, water, and chemical process monitoring. Recent advancements in semiconductor lasers have made spectroscopy economically viable for a host of commercial applications.

SpectraSensors uses highly scientific resources to deliver cost-effective robust measurement tools to customers. SpectraSensors’ products provide unprecedented reliability and speed and require virtually no maintenance.

SpectraSensors have a highly-skilled management team with decades of relevant industry experience, including deep expertise in lasers, optics, process efficiency, and applications and systems design for the gas and petrochemical industries. The team has a proven track record in using optical technologies, including laser absorption spectroscopy, a chemical sensing technique that emphasizes precision, fast response, and immunity to corrosive or contaminating elements in the sensing environment.

SpectraSensors was founded in 2001 as a technology spin-off of the NASA/Caltech Jet Propulsion Laboratory (JPL) in Pasadena, California. Among its customers, in additional Naizak, are Chevron (also an investor in the company), Conoco Phillips and BP.

SpectraSensors will be providing training to personnel of Naizak, as well as to the users of the TDL technology.

Naizak has diversified into the areas of in-Kingdom manufacturing, advanced supply chain programs and providing products, professional solutions and services in the areas of electrical and power, communication, industrial oil field, instrumentation, industrial automation, information technology, enterprise applications, Lab Systems and training and education.

Naizak continues to get involved in the growth of the Saudi economy by taking a leading role in providing products and services from its global partners to address and meet the needs of customers.

“We are delighted to have brought to Saudi Arabia the SpectraSensors technology, which will play a crucial and very important role in the Kingdom’s energy sector, particularly in the field of environmental protection,” said Abdulkarim.

Naizak is a subsidiary of Al Abdulkarim Group, the Gulf’s largest supplier/stockiest of electrical, electromechanical, telecommunication, instrumentation and oilfield components and equipment.

27-Aug-09 11:00 AM

Laser-based analyzer

Jennifer Soto — Mon, 24 Aug 2009 18:00:00 GMT

A new H2O moisture and analyzer technology is available that employs tunable laser diode (TDL) spectroscopy to provide highly accurate and virtually instantaneous measurements of trace amounts of a particular gas (H2O in this instance). By its nature, the TDL based gas detection method is not susceptible to aging affects, making its factory calibration a timeless constant. The result is a very low maintenance analyzer that does not require consumables or scheduled calibration.

TDL-based analyzers have revolutionized the measurement of gases in petrochemical streams such as natural gas. The technology employs a simple measurement that uses a fundamental principle: molecules vibrate when excited by light at specific wavelengths.

24-Aug-09 1:00 PM

TDL-Based Analyzer Eliminates Costly Problems of Inaccurate Acetylene Measurement

Jennifer Soto — Tue, 30 Jun 2009 19:00:00 GMT

One of the most problematic of those impurities is acetylene (C2H2), which can be difficult to measure accurately using conventional analyzers, and can also drift off spec due to slow analyzer response.

Because it is one of the more problematic contaminants that can spoil ethylene production, acetylene is removed from the ethylene during the purifying proves via the Acetylene Converter Unit. This series of reactors converts the acetylene in the hydrogen to form ethylene. When performing accurately, the converter reduces the amount of acetylene down to low PPM or even PPB levels as required.

“Acetylene hinders and damages the catalyst used in the chemical reaction to form polyethylene,” says Al Kania, a veteran of the petrochemical industry. “A big part of the problem is that acetylene, like moisture, is a component that is very difficult to measure accurately through chemical analysis. Also, the few tools that were previously available, such as the gas chromatograph, were unable to go very low in terms of sensitivity.”

Today, however, there is a technology for accurately measuring acetylene content in ethylene. That technology is a sophisticated application of the tunable diode laser (TDL), that was first developed by NASA to measure gas species even in extremely low concentrations.

TDL versus GC

There are several advantages of the TDL-based analyzer over the gas chromatograph (GC), which has been the primary tool for measuring acetylene and other impurities in ethylene until now.

To begin with, the TDL analyzer is extremely accurate, and remains so for the life of the analyzer. It is quite capable of measuring the concentrations of acetylene and other impurities at sub parts per million levels. The TDL analyzer, developed by NASA-spinoff SpectraSensors, Inc., Houston, TX, has become a state-of-the-art tool for accurately and continuously measuring very low levels of moisture, H2S and other impurities in hydrocarbon streams for several years.

The accuracy of the TDL analyzer is especially applicable to measuring acetylene impurities in ethylene today, not only because ethylene is such a valuable commodity, but also because excessive levels of such impurities will corrupt downstream uses of the ethylene.

“In the past, processors used to be able to tolerate a fair amount of acetylene in ethylene. But in polyethylene production, the presence of acetylene above stringent PPM and sometimes PPB levels is unacceptable and creates very expensive waste,” adds Kania.

If an acetylene converter unit operates too aggressively, he says, it could hydrogenate some of the ethylene back into ethane. So, the proper operation of the unit requires the fast and precise monitoring of acetylene in between the first of the two acetylene reactors (mid-bed) and as it exits the final reactor.

In addition to dependable and repeatable accuracy, the speed of measurements is vital to maintaining consistent purity in ethylene production. TDL analyzer offers the advantage of very high-speed readings.

When using the GC technology, the readings are relatively slow, commonly taking from 3 – 6 minutes to provide measurements. Conversely, the TDL analyzer provides almost continuous readings, with intervals taking only from 1-4 seconds.

“When you’re producing a lot of ethylene every day, acetylene and other impurities can swing on you very quickly,” Kania explains. “If you are unaware of those impurities for several minutes, which happens with the GC, you don’t have a chance to reroute the corrupted offspec ethylene. Also, it will take many hours of production, perhaps days, to purge it out of their downstream units. That’s an expensive proposition. On the other hand, the TDL analyzer measures the ethylene as it is manufactured to ensure it is of a very high purity.”

Beyond measurement

In addition to high-speed accuracy, the TDL laser offers ethylene producers other significant benefits over the traditional GC technology.

GCs are traditionally very complex mechanically, and require a lot of labour-based maintenance, Kania says. They also require a lot of consumables in order to maintain proper operation. However, the TDL analyzer requires very little maintenance and no consumables.

“In the past this was not so much of an issue because the ethylene was so valuable that processors simply bit the bullet and put in whatever resources were necessary,” explains Kania. “But the TDL analyzer requires only periodic maintenance, which adds to valuable uptime. And it does not use consumables, which may be secondary, but also adds to the high ROI.”

Another advantage of the TDL analyzer is the ability of ethylene producers to standardize on equipment. In addition to acetylene, there is an assortment of contaminants they need to monitor, and the TDL analyzer is an ideal solution for a large number of these contaminants.

The SpectraSensors analyzer, for instance, measures H2O, NH3, H2S and CO2 as well as acetylene. It is possible for users to standardize on SpectraSensors analyzers, operating them from the same control center.

“When they use multiple units for various contaminants they can roll up the measurements,” Kania says. “By doing this they not only upgrade their analyzer systems but also create more stable operations so that they don’t have to worry about these impurities or over purifying.”

30-Jun-09 2:00 PM

H2S, H2O & CO2 3-Pack gas analyzer system

Jennifer Soto — Mon, 15 Jun 2009 21:00:00 GMT

The SpectraSensors H2S, H2O & CO2 3-Pack gas analyzer systems retain the analytical benefits and reliability known by existing TDL users. Training, support, installation costs, space and overall complexity are reduced by employing one technology for all measurements.

The gas measurements are not affected by glycols, methanol or other corrosives. There is no need for light source or probe replacements, no tape, no carrier gas, and no field calibration.

The system includes all required sample conditioning and regulation. The sample system is heated to 50°C (122°F) to keep all constituents in vapor phase.

15-Jun-09 4:00 PM

Purifying Ethylene With More Precision

Jennifer Soto — Wed, 20 May 2009 21:00:00 GMT

Excessive acetylene contaminants in ethylene make that valuable commodity unusable for polyethylene production. Fast, repeatable and dependable, the laser-based analyzer constantly measures acetylene contaminants during ethylene production, assuring high-quality product while eliminating costly waste.

The purity of ethylene feedstock is critical to the quality of a wide range of petrochemical products, particularly polyethylene plastics. Yet, periodically there are problems when contaminant concentrations exceed stringent purity specifications, rendering valuable ethylene feedstock unacceptable for use in producing such materials. One of the most problematic of those impurities is acetylene (C2H2), which can be difficult to measure accurately using conventional analyzers, and can also drift off spec due to slow analyzer response.

Because it is one of the more problematic contaminants that can spoil ethylene production, acetylene is removed from the ethylene during the purifying process via an acetylene converter unit. This series of reactors reacts hydrogen with acetylene to form ethylene. When performing accurately, the converter reduces the amount of acetylene down to low parts per million (PPM), or even parts per billion (PPB), levels as required.

“Acetylene hinders and damages the catalyst used in the chemical reaction to form polyethylene,” says Al Kania, a veteran of the petrochemical industry. “A big part of the problem is that acetylene, like moisture, is a component that is very difficult to measure accurately through chemical analysis. Also, the few tools that were previously available, such as the gas chromatograph (GC), were unable to go very low in terms of sensitivity.”

Today, however, there is a technology to accurately measure acetylene content in ethylene. That technology is a sophisticated application of the tunable diode laser (TDL), which was first developed by NASA to measure gas species even in extremely low concentrations.

TDL Vs. GC
There are several advantages of the TDL-based analyzer over the GC, which has been the primary tool for measuring acetylene and other impurities in ethylene until now. To begin with, the TDL analyzer is extremely accurate and remains so for the life of the analyzer. It is quite capable of measuring concentrations of acetylene and other impurities at sub-PPM levels. The TDL analyzer, developed by NASA spin-off SpectraSensors Inc., has become the state-of-the-art tool for accurately and continuously measuring very low levels of moisture, H2S and other impurities in hydrocarbon streams for several years.

“In the past, processors used to be able to tolerate a fair amount of acetylene in ethylene. But in polyethylene production, the presence of acetylene above stringent PPM, and some times PPB, levels is unacceptable and creates very expensive waste,” according to Kania.

Kania adds that if an acetylene converter unit operates too aggressively, it could hydrogenate some of the ethylene back into ethane. So, proper operation of the unit requires the fast and precise monitoring of acetylene in between the first of the two acetylene reactors (mid-bed) and as it exits the final reactor.

In addition to dependable and repeatable accuracy, the speed of measurements is vital to maintaining consistent purity in ethylene production. This TDL analyzer, furthermore, offers the advantage of very high-speed readings. When using GC technology, the readings are relatively slow, commonly taking from three to six minutes to provide measurements. Conversely, the TDL analyzer provides virtually continuous readings, with intervals taking only from one to four seconds.

“When you’re producing a lot of ethylene every day, acetylene and other impurities can swing on you very quickly,” Kania explains. “If you are unaware of those impurities for several minutes, which happens with the GC, you don’t have a chance to reroute the corrupted off-spec ethylene. Also, it takes many hours of production, perhaps days, to purge it out of downstream units. That’s an expensive proposition. On the other hand, the TDL analyzer measures the ethylene as it is manufactured to ensure it is of a very high purity.”

Beyond Measurement

In addition to high-speed accuracy, the TDL laser offers ethylene producers other significant benefits over traditional GC technology.

Conventionally, for instance, GCs are very complex mechanically and require a lot of labor-based maintenance, according to Kania. They also require a lot of consumables in order to maintain proper operation. However, the TDL analyzer requires very little maintenance and no consumables.

“In the past, this was not so much of an issue because the ethylene was so valuable that processors simply bit the bullet and put in whatever resources were necessary,” indicates Kania. “But the TDL analyzer requires only periodic maintenance, which adds to valuable uptime. And it does not use consumables, which may be secondary, but it also adds to the high return on investment.”

The SpectraSensors analyzer, for instance, measures H2O, NH3, H2S and CO2, as well as acetylene. It is possible for users to standardize on SpectraSensors analyzers, operating them from the same control center.

“When users use multiple units for various contaminants, they can roll up the measurements,” Kania says. “By doing this, they not only upgrade their analyzer systems, but also create more stable operations, so that they don’t have to worry about these impurities or over-purifying.”

SpectraSensors manufactures optically based gas analyzers and moisture analyzers for analytical process markets, and uses TDL absorption spectroscopy in an array of products, such as ambient air monitoring, moisture analyzers and gas analyzers for natural gas pipelines and processors, petrochemical refineries and chemical companies. For more information from the company, please call 800.619.2861 or visit www.spectrasensors.com.

20-May-09 4:00 PM

Making Analyzers that Work in the Real World

Jennifer Soto — Thu, 01 Jan 2009 20:00:00 GMT

If you work in a process plant, you probably have had some frustrating experiences with analyzers. They’re vital to process measurement and control, but keeping them running can be a real pain. Why can’t someone make an analyzer that works as well and as reliably as a pressure, a temperature or a flow transmitter?

The problems with analyzers are twofold. First, the measurements that have to be made are often a complex and frequently involve chemical reactions. Analyzing chemical composition is always going to more difficult than measuring pressure.

Seconds, many analyzer vendors have roots in making lab instruments for controlled and continuously monitored environments. Adapting these analyzers for on-line operation and field installation while making them rugged enough to not need daily maintenance has been too high a hurdle for many lab instrument vendors.

Now, new entrants from completely different industries are making their mark. For examples, SpectraSensors (www.spectrasensors.com) was started in 1999 to commercialize products adapted from NASA/Caltech Jet Propulsion Laboratory. Because the original products were designed for mission-critical aerospace applications, high reliability and low maintenance were a given.

The challenge was to adapt these aerospace-quality analyzers for industrial use and make them affordable. So, SpectraSensors focused on optical, laser-based gas analyzers for energy and petrochemical industry applications.

The company’s tunable diode laser (TDL) technology measures moisture and carbon dioxide. SpectraSensors also provides custom configurations for measurement of other compounds, such as methane, acetylene, ammonia, hydrogen chloride, hydrogen sulfide, carbon monoxide and nitrogen monoxide.

A leading application for SpectraSensor’s TDL analyzer is in refinery catalytic reformer units. These units convert naphtha streams into higher octane aromatic compounds that can be used in gasoline blending or chemical plants.

All of these compounds must be accurately measured and controlled, or their concentrations can increase until they poison the catalysts in the reactors. Hydrogen sulfide and ammonia must be minimized, while the right balance of moisture and hydrogen chloride must be maintained to extend the time between catalyst regeneration cycles and improve yields.

“All of the measurements can be performed on-line with TDL analyzers, which require less maintenance and are more reliable than previous methods,” says Bill Jenko, SpectraSensors’ director of process product line management.

“The most compelling is hydrogen chloride measurement, which typically is done manually with stain tubes, a handheld off-line measurement method subject to operator-induced variability. Some refineries use stain tubes to measure sulfur and ammonia as well. The ability to move these measurements from manual off-line to continuous on-line reduced operational costs, and improves the production of the reformate and the hydrogen,” adds Jenko.

Concentrations measured vary by application, but a typical dual-range analyzer might measure 0 ppm to 50 ppm and 0 ppm – 1,000 ppm hydrogen chloride.

“Some plants have existing on-line analyzers for moisture measurement, but I haven’t heard of any other proven technology for on-line hydrogen chloride or ammonia measurements in these streams,” claims Jenko.

Jenko says TDL has some advantages that improve reliability and reduce maintenance. “TDL analyzers require no carrier gas or other consumable gases, and this lowers cost of ownership over other technologies. TDL hydrogen chloride and ammonia analyzers need a scrubber because they’re based on differential spectroscopy, but the scrubbers are the only consumable and typically last at least a year.”

1-Jan-09 2:00 PM

TDL Technology Promises Improved Process Control in Gas Plants

Jennifer Soto — Fri, 05 Dec 2008 19:00:00 GMT

Confronted with increasing costs and product integrity issues, the hydrocarbon processing industry has become increasingly dependent on sensors for detection and measurement of impurities in gas streams. For some sensing technologies this can be a hit and miss situation that can compromise process control and result in costly actions including high maintenance costs, unplanned shutdowns and unanticipated shut-ins where the buyer can block the seller from shipping gas.

Gas processing plants require fast and accurate measurements of moisture (H2O), hydrogen sulfide (H2S), and carbon dioxide (CO2) because these contaminants damage expensive equipment such as turbo-machinery and pipelines, shorten desiccant, contactor, or mole sieve lifetimes, and threaten the operator’s ability to maintain tight process control and product quality. In some cases, the gas processor’s downstream customer can shut in their supplier which costs hundreds of thousands of dollars. Tunable Diode Laser (TDL) based analyzers are increasingly being used in these “pain-point” analytical applications to measure contaminants reliably while reducing maintenance and operating costs. TDL absorption spectroscopy employs a laser mounted behind a window that protects it from the wear and tear of caustic gas contents, while enabling the analyzer to accurately and quickly read varying gas concentrations. The laser does not come into contact with the gas and calibration does not change or drift over time (Figure 1 and 2).

Dependable H2O Analysis

Impurities such as moisture and corrosive acids found in many gas streams are the nemesis of conventional sensors, which are directly exposed to the gas stream and those harmful elements. Over time—and sometimes within a few weeks— those probes become damaged and inaccurate, resulting in costly repair or replacement. In the meantime, corrosion and contamination from problematic impurities can damage equipment, catalysts, desiccants and processes.

The TDL-based analyzer allows the gas processors, whether they are sweetening, dehydrating, or removing various impurities, to monitor and measure the inputs and outputs of their processes for CO₂, acids, moisture and H₂S. Furthermore, it accurately takes repeatable measurements within seconds, whereas conventional devices often take many minutes.

Excessive dehydration costs may be incurred because of inaccurate moisture readings or concern on the part of the operator that the gas may be too wet. In many cases, it is necessary to over-process the gas in order to achieve quality specs for multiple customers when taking into consideration the risk of inaccurate measurements and potential false shut-ins. The availability of a fast and reliable measurement allows the plant to confidently deliver gas that is within specifications.

The TDL-based technology is very fast and does not drift, thereby enabling operators to keep dehydration costs to a minimum—without fear of a shut-in. (Figure 3)

Accurate H2S Sweetening

For monitoring and measuring H₂S in gas streams, lead acetate tape analyzers are frequently the technology of choice. In that design, gas is sent directly through the lead acetate tape, which changes color when reacting with sulfur. The system analyzes the color change with a photometer. However, the lead acetate tape is a consumable that is directly exposed to the gas stream. Tape reels must be changed periodically (weekly or monthly), and if there is a system leak, it exposes the whole tape. Also, the used tape is considered hazardous waste, and must be disposed of accordingly.

Some processors use a UV photometer for measuring H₂S. Natural gas may have varying percentages of methane, propane and possibly more than a dozen other components. The measurements results of UV photometers are susceptible to gas composition changes. When the background matrix of the gas changes, that often causes erroneous readings and consequential problems.

For H₂S applications, the TDL-based analyzer measures sour gas going into processing, and sweetened gas coming out. Fast analyzers enable better control of processes by letting the processor know instantly how much processing is needed and provides for faster shut-off when the sweetened gas is not up to required standards. Changes in gas concentrations can be seen immediately with TDL analyzers preventing false alarms, false readings and unwarranted shutdowns.

LNG Applications

The presence of even trace amounts of H₂O or CO₂ can threaten the integrity of processing equipment during compression and liquefaction of natural gas due to ice formation. It is essential to have very fast H₂O or CO₂ detection in order to improve the life of the desiccant while retaining product quality.

In the past, LNG (liquid natural gas) and NGL (natural gas liquids) gas processors have relied on surface based analyzers such as electrochemical and quartz crystal cells to measure trace amounts of moisture in process streams. Although these devices may perform with acceptable accuracy at first, the confidence level in their measurements soon becomes low, due to drift, the inability to read high concentrations of moisture, and the tendency for their sensor probes to become desensitized by the gas streams they are measuring. Such situations have led to excessive maintenance and high operational costs.

The TDL-based gas detection method does not experience aging effects, making its factory calibration a timeless constant. The result is a very low maintenance analyzer that does not require consumables or scheduled calibration.

Emphasis on Process Industries

Although TDL-based analyzers have been widely accepted by the natural gas production and pipeline transmission industry, this technology is fairly new to the process industry. However, because the need for improved process control and reduced costs are equally if not even greater among processors, there has been immediate interest in applying this technology throughout the petrochemical industry. Thousands of TDL analyzers are now installed at operations from off shore production to processing and refining, to chemical plants and emissions monitoring.

Note: Gases & Instrumentation periodically publishes articles about the technology of new products or innovative technologies introduced into existing products. This is to explain the technology in a non-commercial way to inform potential end-users of technology that may suit their application.

Gases & Instrumentation does not verify the test results noted, nor does Gases & Instrumentation endorse these products. The technology is presented for informational purposes only.

5-Dec-08 1:00 PM

Gas Analyzer Technology Boosts Potential For Converting Biogas To Electric Power

Jennifer Soto — Sat, 01 Nov 2008 14:00:00 GMT

The ability of advanced, laser-based sensors to detect moisture, hydrogen sulfide and other contaminants in gases can smooth the way for biogas as a resource for electric utilities.

Wouldn’t it be great if some of the expensive green power programs you hear about actually worked? Experts and financiers are predicting it will take billions of investment dollars and decades to get any meaningful quantity of energy from alternative resources.

Perhaps not. One of the oldest and most widespread forms of potential energy — methane gas — promises to give those efforts a sizable boost — right now.

The main component of “natural gas,” methane is found in abundance in many places other than subterranean gas wells. Landfills, oil pipelines, pasturelands, forests and waste treatment plants all contain methane or the biomass from which methane can be formed.

“Although methane gas contains plenty of energy, until recently the gas available from many sources has been considered economically unviable as a source of energy,” explained Sam Miller, a senior official with SpectraSensors, Inc., Houston, TX.

“Whatever the source of methane, you have to get it to market, which often means getting it into a pipeline that delivers gas to users such as power plants and industrial companies,” he said.

Transporting and marketing methane through pipelines requires that it meet safety and quality standards, Miller said. Virtually all biogas contains significant amounts and varieties of impurities that must be removed before pipelines will transport it and customers will accept it. Such impurities can disrupt the flow of gases, damage pipelines and contaminate the air with toxins that can be deadly to breathe.

PG&E Harnesses Cow Power

Last spring BioEnergy Solutions, Bakersfield, CA, launched California’s first biogas-to-pipeline injection project in Fresno County, central California. The project is using renewable natural gas derived from animal waste at a PG&E site.

“With nearly 2 million dairy cows in California, there is great potential for the state’s agriculture and power sectors to work together to address the challenges of climate change,” said Roy Kuga, vice president of energy supply at PG&E. “This project is yet another example of our company’s commitment to add innovative forms of clean renewable energy to help meet our customers’ future power needs.”

PG&E is one of California’s largest investor-owned utilities. The state’s recently enacted Renewable Portfolio Standard (RPS) Program requires each utility to increase its procurement of eligible renewable generating resources to achieve a goal of 20% of load by 2010. The RPS Program was passed by the California Legislature and is managed by the CPUC and California Energy Commission.

Under a long-term contract approved by the California Public Utilities Commission (CPUC), BioEnergy Solutions will deliver up to 3 Bcf of renewable natural gas a year to PG&E. Using SpectraSensors’ laser-based gas analyzer technology, this is the first project in California to deliver pipeline-quality, renewable biogas to a utility.

“We are using these analyzers to monitor moisture in the methane,” said David Albers, BioEnergy Solutions president. “And of course we’re checking for hydrogen sulfide content and carbon dioxide content.”

Albers said the project, located in the town of Riverdale in western Fresno County, will use manure from the Vintage Dairy’s 5,000 milk-producing cows and calves. The waste is flushed into a covered lagoon — equal in size to the area of nearly five football fields and over three stories deep — that traps the methane gas produced as the manure decomposes. The biogas is upgraded, or “scrubbed,” to remove corrosive materials to meet PG&E’s industry-leading environmental standards for power plants and then delivered to PG&E through the utility’s pipeline.

PG&E uses the natural gas to deliver renewable electricity to its customers in central and northern California. The methane production system also reduces emissions of methane, a greenhouse gas 21 times more potent than carbon dioxide, by 70%.

Albers said SpectraSensors moisture analyzer offers assurance that the project will continually meet PG&E’s high standards. He said that in addition to offering the highest reliability of gas analyzers, this technology has a track record for considerably lower maintenance costs in both labor and consumables.

PG&E, a leader in utilizing biogas, is also a user of SpectraSensors technology. In addition to the utility’s contract with BioEnergy Solutions, it is working to cultivate the next generation of biogas technologies through its biomethanation research project.

Depending on what impurities might be contained in “polluted” gas — substances such as H2O, H2S, CO2, unsaturated hydrocarbons and glycols — it is vital to use monitoring equipment that can accurately read the levels of contaminants in gas streams.

The “gas analyzer” technology needed to quickly and accurately measure a wide variety of contaminants and background gases has been advanced to new heights by SpectraSensors, which makes Miller optimistic about the safety and economic viability of using non-standard sources of methane and other biofuels.

“There has been a significant rise in activity in production and distribution of ‘green gas’ as an alternate fuel,” he said. “Our company considers this a growth market. And while a primary market for our analyzer instruments include pipeline-quality natural gas from traditional producers, we can also help nontraditional producers deliver clean methane to various power generation customers.”

Miller cited several examples of sources for methane, which together could amount to a very sizable reduction of greenhouse gases as well as renewable resource for generating electric power for a grid that every year experiences added demand and will soon have to accommodate plug-in passenger cars.

“Waste-to-energy methane from human and livestock digesters has the potential to become a major source,” he said. “But other, smaller sources are becoming increasingly viable. For instance, the methane gas pockets present in pipeline oil have traditionally been burned off when it reached the oil refinery. Now, it is economically feasible to feed that gas into a gas pipeline and use it to generate electricity.”

The patented technology that SpectraSensors employs in its gas analyzers is tunable diode laser (TDL)-based absorption spectroscopy. This is an optical measurement technology used to detect moisture (H2O), carbon dioxide (CO2), hydrogen sulfide (H2S), ammonia (NH3), oxygen (O2) and more.

In the traditional natural gas production and pipeline market this technology has become the de facto standard for ensuring consistently accurate readings in gas streams. Not only is it in use among many leading pipeline operators, but is also the technology of choice among leading utility companies.

Fast, Accurate And Lower In Costs

Essentially, the SpectraSensors TDL-based gas analyzer uses laser (light) absorption spectroscopy to identify and measure one or more gases in a flow of mixed gases. This type of analyzer is typically “tuned” to monitor a target gas (e.g. H20, CO2, H2S) by monitoring the absorption of light at wavelengths specific to the target gas.

The SpectraSensors gas analyzer line is designed to provide extremely fast and accurate readings without expensive labor and replacement costs. That is because the gas is analyzed away from the stream in a sample cell. As the laser light passes through the gas sample in the cell, the presence of any target gas is detected and its concentration measured.

“This design is very process worthy,” said Miller. “The TDL-based analyzer technology has proven to be so reliable and trustworthy that it is the new standard in the natural gas pipeline industry, and is being adopted by oil refineries, petrochemical plants and process industries all over the world.”

1-Nov-08 9:00 AM

Improving Process Control with TDL Technology

Jennifer Soto — Wed, 01 Oct 2008 19:00:00 GMT

Confronted with increasing costs and product integrity issues, the hydrocarbon processing industry has become increasingly dependent on sensors for detection and the measurement of impurities in gas streams. For some sensing technologies, this can be a hit and miss situation that can comprise process control and result in costly actions, including high maintenance costs, unplanned shutdowns and unanticipated shut-ins.

Protecting expensive process equipment

Gas processing plants require fast and accurate measurements of moisture (H2O), hydrogen sulphide (H2S) and carbon dioxide (CO2), because these contaminants damage expensive equipment such as turbo-machinery and pipelines; shorten desiccant, contractor or molecular sieve lifetimes; and threaten the operator's ability to maintain tight process control and product quality. In some cases, the gas processor's downstream customer can shut in their supplier, which costs hundreds of thousands of dollars.

1-Oct-08 2:00 PM

SpectraSensors Ranked Fifth on Inc. Magazine's List of the Top 50 Environmental Services Companies in America

Jennifer Soto — Tue, 26 Aug 2008 14:00:00 GMT

Houston, TX – August 26, 2008 – SpectraSensors, Inc. has been ranked fifth on Inc. Magazine’s list of the 50 fastest-growing private American companies in the environmental category, which includes a broad range of product and services companies. The company placed 583rd on the Inc. 5,000 list of the fastest-growing private companies in the U.S., with nearly 600 percent revenue growth from 2004 through 2007. SpectraSensors is a leading manufacturer and supplier of precision optical laser-based gas analyzers used by the natural gas, petrochemical, clean tech and environmental monitoring industries to improve efficiency and product quality.

“Our second annual Inc. 5,000 continues the most ambitious project in business journalism,” said Inc. 5,000 project manager Jim Melloan. “The Inc. 5,000 gives an unrivalled portrait of young, underreported companies across all industries doing fascinating things with cutting-edge business models, as well as older companies that are still showing impressive growth.”

SpectraSensors was founded in 2001 as a technology spin-off of the NASA/Caltech Jet Propulsion Laboratory (JPL) in Pasadena, Calif. The company uses tunable diode lasers (TDLs) to improve the quality and efficiency of natural gas and petrochemical processing and to conduct environmental monitoring in a host of clean tech applications. It enables customers such as Chevron (also an investor in the company), ConocoPhillips and BP to operate in a cleaner and safer manner while also helping to improve product yields.

For example, in the clean tech market, SpectraSensors is helping Pacific Gas & Electric (PG&E) to harvest and transport methane (CH4) as a safe, clean energy source. The company is also aiding weather forecasters in limiting commercial flight delays that cost the airline and freight industries more than $1 billion annually in wasted time and fuel.

“Our growth over the last several years has been sharply tied to the rise of energy prices and the energy industry’s strong desires to increase efficiency and improve product quality,” said George Balogh, CEO of SpectraSensors, Inc. “The industry is rapidly becoming more automated, which is fueling increased demand for our products and the added speed and reliability they enable.”

Unlike other sensor devices, SpectraSensors’ products provide continuous, real-time monitoring capabilities. They supply unprecedented reliability and speed and require virtually no maintenance. The company’s standard products include moisture (H2O) sensors for atmospheric measurement, plus sensors that assess moisture and carbon dioxide (CO2) levels in natural gas as it is transported through pipelines. Process applications are available for the measurement of other compounds.

The 2008 Inc. 5,000 list measures revenue growth from 2004 through 2007. To qualify, companies must be U.S.-based, privately held and independent – not subsidiaries or divisions of other companies – as of December 31, 2007 and have had at least $200,000 in revenue in 2004 and at least $2 million in revenue in 2007.

# # # #

About Inc. Magazine
Founded in 1979 and acquired in 2005 by Mansueto Ventures, LLC., Inc. magazine (www.inc.com) is the only major business magazine dedicated exclusively to owners and managers of growing private companies that delivers real solutions for today’s innovative company builders. With a total paid circulation of approximately 700,000, Inc. provides hands-on tools and market-tested strategies for managing people, finances, sales, marketing and technology.

About SpectraSensors, Inc.
SpectraSensors, Inc. is a leading manufacturer of optically based gas and moisture analyzers for analytical process markets. SpectraSensors uses Tunable Diode Laser (TDL) Absorption Spectroscopy in an array of products such as Ambient Air Monitoring, Moisture Analyzers (Hygrometers) and Gas Analyzers for Natural Gas Pipelines and Processors, Petrochemical Refineries and Chemical Companies. SpectraSensors’ gas analyzers measure moisture (H2O), carbon dioxide (CO2), hydrogen sulfide (H2S), methane (CH4), ammonia (NH3) and more.

26-Aug-08 9:00 AM

Analyzer Technology Boosts Potential for Converting Biogas to Power

Jennifer Soto — Thu, 03 Jul 2008 20:00:00 GMT

The ability of advanced, laser-based sensors to detect moisture, hydrogen sulfide and other contaminants in gases can smooth the way for biogas as a resource for electric utilities. Wouldn’t it be great if some of the expensive Green Power programs you hear about actually worked? Experts and financiers are predicting it will take billions of investment dollars and decades to get any meaningful quantity of energy from alternative resources. Maybe not. Maybe not. One of the oldest and most widespread forms of potential energy – methane gas – promises to give those efforts a sizable boost – right now.

3-Jul-08 3:00 PM

TDL-based moisture analyzers can offer high return on investment for refinery

Jennifer Soto — Wed, 14 May 2008 15:00:00 GMT

Tunable-Diode Laser-based moisture sensors help ensure long catalyst life, reduce operational costs, and offer the lowers overall cost of ownership.

Refineries and chemical plants have long been subjected – perhaps unwittingly - to high costs incurred from failure of conventional moisture analyzer to accurately read moisture intrusion in feedstocks and hydrogen recycle streams, vital to optimizing product yield and catalyst life.

Because typical analyzers, such as those based on surface absorption or adsorption, employ sensors that are exposed directly to harsh elements in the streams they monitor, timely and accurate moisture readings may be disrupted within a relatively short period of time. The disruptive operational life leads to substantial costs that can range from exorbitant consumables and maintenance to conceivably hundreds of thousands of dollars for premature catalyst recharging or untimely interruption of continuous processes.

The innovative employment of tunable diode laser (TDL) technology has enabled the development of a new moisture technology — the laser-based spectroscopy moisture analyzer. One such device, developed as a spin-off of NASA-JPL space technology by SpectraSensors, Inc. (San Dimas, CA), continuously samples reformer streams without coming into contact with them, thereby avoiding destructive contents such as hydrochloric acid, which can quickly damage (“poison”) a surface-absorption based sensor. Moreover, the surface based sensors may not be entirely disabled, or it may drift for a number of reasons and may continue to transmit inaccurate moisture readings until catalyst life has been compromised.

The TDL-based sensor can provide refineries and chemical processors with a high return on investment (ROI) based on avoidance of tangible costs, such as consumables, as well as extremely high intangible costs, such as catalyst recharging and process interruptions.

Tangible costs are greatly reduced through the use of the TDL based moisture analyzer. While initial purchase price is somewhat higher, the reduced operating costs of this technology are likely to overcome this initial investment quickly. These devices can run for years without requiring maintenance, recalibration or replacement. Therefore, costs such as analyzer technicians, repair or replacement of probes, as well as an inventory of spare sensor heads are eliminated.

During turnovers or other abnormal process events, moisture slugs can render conventional moisture sensors “blind” for hours or days. For this reason, refineries have resorted to building in redundant analyzers and the associated sample handling conditioning and stream switching. This can double or triple the installed costs!

Speed and reliable measurements characterize TDL-based moisture analyzers. They are about to detect moisture problems with extremely high accuracy and measurement intervals as frequent as within a second, enabling practically instantaneous response. This helps to eliminate the chance that moisture will get through “reading time gaps” that are often several minutes or hours in duration with conventional sensors.

14-May-08 10:00 AM

PinPoint Precision - Sam Miller, SpectraSensors Inc., USA, examines how a TDL based analyser pinpoints moisture intrusion and trace H2S levels in refinery operations.

Jennifer Soto — Fri, 01 Feb 2008 16:00:00 GMT

The emergence of tuneable diode laser (TDL) based technologies has been a major development in many industries, and has created valuable opportunities for refineries and chemical plants to maximise productivity while avoiding high maintenance costs.

By instantly and accurately pinpointing the presence of moisture, HCl, H2S and other impurities in feedstock and fuel gas streams, the TDL based gas analyser is able to provide significant benefits. Among those are the prevention of foreshortened lifespan of costly catalysts, enhanced assurance of product quality, reduced turnaround recovery times, and avoidance of unscheduled shutdowns.

What is a TDL?

A tuneable diode laser is a type of semiconductor based laser that can be tuned to optically select a very specific wavelength (or colour) of light. NASA’s jet propulsion laboratory (JPL) developed long wavelength (near infrared) tuneable lasers and processor controls that enable users to precisely ‘target’ specific modules and detect trace elements in gas. This spectroscopy technology was vital to research and operations in the Space Station and Mars Polar Lander programs as well as studies on global warming, emissions, weather and climates throughout the world.

TDLs emit near infrared light at wavelengths that can be absorbed by the gas being measured (e.g. CO2, H2S, H2O, HCl). The laser’s light passes though the gas sample, and then is measured by a solid state detector. As the laser’s wavelength is swept or ‘tuned’ across a specific wavelength, energy is absorbed, reducing the amount of light arriving at the detector at that specific wavelength only. The result is a sharp peak shaped curve (Figure 1). The fraction of light absorbed (the peak height) is directly proportional to the concentration of the associated target gas.

As the laser is tuned across the line multiple times per second, it can be used for fast, accurate measurements and control of process parameters. TDL gas analysers have the ability to react quickly to upset conditions without the risk of false alarms.

Design

The TDL based spectrometer’s optical design is a critical factor in terms of accuracy, repeatability and durability. The nature of the optical design developed by SpectraSensors is such that the sample flows though the chamber and the sensor is isolated behind a window, rather than in the stream of gas. By doing so, the accuracy of the analyser is not affected by the gas or impurities, which are harsh enough to debilitate the accuracy and service life of conventional electromechanical analysers.

For example, the presence of moisture or hydrogen chloride in a reformer of a refinery can ‘poison’ the catalysts. Undetected and untreated moisture slugs can result in the premature degradation of catalysts, costly unscheduled process downtime or possibly requiring replacement of this exceedingly expensive material. Slugs of moisture can render conventional electrochemical sensors useless for a period due to a required ‘dry down’ time. Such an event makes those sensors inoperative at a time when they are needed most.

For refineries, the ultimate danger of dry down lapses is not only potential damage to the reactor catalyst, but also that ‘off spec’ materials might be inadvertently produced, both of which could cost a refinery hundreds of thousands of dollars or more.

In the same situation the TDL based analyser is not affected by the moisture slug, and has zero dry down time. Rather, this technology utilises absorption spectroscopy that safely measures moisture from behind the non wetted side of an optical window.

H2S measurement

For H2S measurement, the hazardous waste, costs, and maintenance issues associated with ‘traditional’ analysers, such as lead, acetate, tape systems, UV analysers, chromatographs and other technologies, are also now being avoided via the TDL based H2S analyser. One of the major benefits of the TDL based analyser for this application is the avoidance of hazardous waste, a major drawback of lead acetate tape systems. Lead acetate tape is a consumable that must be changed weekly or monthly. Once used, the tape must be disposed of in a manner that is both costly and inconvenient. If there is a system leak, the entire tape is exposed, causing considerable added expense.

UV analysers used for H2S measurement require light source replacement, and are often ‘confused’ by interfering background gas components. Fuel gases have varying percentages of H2S as well as other gas components.

UV photometer measurement results are susceptible to changes in composition: that is, when the fuel gas background matrix changes, erroneous readings, and consequential problems, often occur.

The other traditional H2S measurement technology, gas chromatography, is a highly complex system and requires trained experts to operate. Those factors are contrary to the trend of refineries and chemical plants, which is to reduce required manpower for maintenance through automation. Here again the TDL based analyser measures both sweet and sour gas though a window outside the stream, avoiding contact with caustic gases. The changing gas matrix does not confuse the tuneable laser.

For H2S analysis, the TDL based analyser measures sour gas headed for processing and sweetened gas coming out. Because it provides faster readings, process control is improved by instantly letting operators know how much processing is needed. Also, when exit gases do not meet specifications, shutoff can be performed immediately, while false alarms and unwarranted shutdowns can be virtually eliminated.

In addition to enhanced accuracy and process control, the TDL based H2S analyser offers consistent repeatability as well as low operational costs. This greatly reduces the cost of ownership and virtually eliminates technician support while providing accurate and stable calibration throughout the life of the analyser. Each SpectraSensors unit is preset at the factory, so it is truly ‘plug and play’ and requires little training.

While initial purchase price is somewhat higher, the reduced operating costs of this technology are likely to overcome this initial investment quickly. These devices can run for years without requiring maintenance, recalibration or replacement. Therefore, costs such as analyser technicians, repair or replacement of probes, as well as an inventory of spare sensor heads are eliminated.

The TDL based gas analyser has become the de facto standard in the natural gas industry, where producers, processors and pipeline operators have been upgrading to this technology for several years.

1-Feb-08 10:00 AM

NASA Moisture Analyzer Technology Delivers Imporved Process Control in Hydrocarbon Plants

Jennifer Soto — Tue, 01 Jan 2008 17:00:00 GMT

Ultra-fast and highly accurate, a new Tunable Diode Laser analyzer technology is being adopted by petrochemical plants, refineries and gas processors, reducing maintenance while providing enhanced control over process integrity

TDL Technology

A tunable diode laser (TDL) is a type of semiconductor-based laser that can be tuned to a very specific wavelength (or color) of light. NASA's Jet Propulsion Laboratory (JPL) developed long wave length (near infrared) tunable lasers and processor controls that enable users to precisely "target" specific molecules and detect trace elements in gas (Figure 1). This technology was vital to research and operations in the Space Station and Mars Polar Lander programs as well as studies on global warming, emissions, weather and climates throughout our world.link

1-Jan-08 11:00 AM

Improve process control in gas plants using tunable diode laser spectroscopy

Jennifer Soto — Tue, 01 Jan 2008 16:00:00 GMT

Tunable diode laser (TDL)-based analyzers (Fig. 1) are increasingly being used in these “pain-point” analytical applications to measure contaminants reliably while reducing maintenance and operating costs.

TDL absorption spectroscopy uses a laser mounted behind a window that protects it from the wear and tear of caustic gas contents while enabling the analyzer to accurately and quickly read varying gas concentrations. The laser does not come into contact with the gas and calibration does not change or drift over time.

Dependable H2O analysis.

Impurities, such as H2O and corrosive acids found in many gas streams, are the nemesis of conventional sensors that are directly exposed to the gas stream and those harmful elements. Over time—and sometimes within a few weeks—those probes become damaged and inaccurate, resulting in costly repair or replacement. In the meantime, corrosion and contamination from problematic impurities can damage equipment, catalysts, desiccants and processes.

The TDL-based analyzer allows gas processors, whether they are sweetening, dehydrating or removing various impurities, to monitor and measure the inputs and outputs of their processes for CO2, acids, H2O and H2S. Additionally, it accurately takes repeatable measurements within seconds, whereas conventional devices often take minutes.

Excessive dehydration costs may be incurred due to inaccurate H2O readings or concerns that the gas may be too wet. In many cases, it is necessary to over-process the gas in order to achieve quality specifications for multiple customers when taking into consideration the risk of inaccurate measurements and potential false shut-ins.

Fast and reliable measurement availability allows the plant to confidently deliver gas that is within specifications. TDL-based technology is very fast and does not drift, thus enabling operators to keep dehydration costs to a minimum—without fear of a shut-in.

Accurate H2S sweetening.

For monitoring and measuring H2S in gas streams, lead acetate tape analyzers are frequently the technology of choice. In that design, gas is sent directly through the lead acetate tape, which changes color when reacting with sulfur. The operator then analyzes the color change with a photometer. However, the lead acetate tape is a consumable that is directly exposed to the gas stream. Tape reels must be changed periodically (weekly or monthly), and if there is a system leak, it exposes the whole tape. Also, the used tape is considered hazardous waste and must be disposed of accordingly.

Some processors use an ultraviolet (UV) photometer for measuring H2S. Natural gas may have varying percentages of methane, propane and possibly more than a dozen other components. UV photometer measurement results are susceptible to gas composition changes. When the gas background matrix changes, it often causes erroneous readings and consequential problems.

For H2S applications, the TDL-based analyzer measures sour gas going into processing, and sweetened gas coming out. Faster analyzers improve processes control by letting operations know instantly how much processing is needed and providing for faster shutoff when the sweetened gas does not meet specifications. Changes in gas concentrations can be seen immediately, with TDL analyzers preventing false alarms, inaccurate readings and unwarranted shutdowns.

Liquefied natural gas (LNG) applications.

Even trace amounts of H2O or CO2 can threaten processing equipment integrity during natural gas compression and liquefaction due to ice formation. It is essential to have very fast H2O or CO2 detection in order to improve the life of the desiccant while retaining product quality.

In the past, LNG and natural gas liquids processors have relied on surface-based analyzers such as electrochemical and quartz crystal cells, to measure trace H2O in process streams. Although these devices may perform with acceptable accuracy at first, the confidence level in their measurements soon becomes low, due to drift, the inability to read high H2O concentrations and the tendency for the sensor probes to become desensitized by the gas streams they are measuring. Such situations have led to excessive maintenance and high operational costs.

The TDL-based gas detection method does not experience aging effects, making its factory calibration a constant. The result is a very low-maintenance analyzer that does not require consumables or scheduled calibration.

Emphasis on process industries.

Although TDL-based analyzers have been widely accepted by the natural gas production and pipeline transmission industry, this technology is fairly new to the processing industry. Because the need for improved process control and reduced costs is equally in demand among processors, there has been immediate interest in applying this technology throughout the petrochemical industry. Thousands of TDL analyzers are now installed from offshore production to processing and refining, chemical plants and emissions monitoring.

This analyzer technology is replacing conventional sensors to improve the bottom line

Confronted with increasing costs and product integrity issues, the hydrocarbon processing industry has become increasingly dependent on sensors for detecting and measuring impurities in gas streams. For some sensing technologies, this can be a hit-or-miss situation that can compromise process control and result in costly actions including high maintenance costs, unplanned shutdowns and unanticipated shut-ins.

Gas processing plants require fast and accurate moisture (H2O), hydrogen sulfide (H2S) and carbon dioxide (CO2) measurements because these contaminants damage expensive equipment such as turbo-machinery and pipelines, shorten dessiccant, contractor or mole sieve lifetimes, and threaten the operator's ability to maintain tight process control and product quality. In some cases, the downstream customer can shut in their supplier which can costs hundreds of thousands of dollars.

1-Jan-08 10:00 AM

Analyzer inaugurated for speciality gases markets

Jennifer Soto — Sat, 01 Sep 2007 15:00:00 GMT

A NEW LASER-based moisture analyzer, measuring trace moisture in process and speciality gases, has been introduced by SpectraSensors of California, a leading provider or optically orientated gas sensors for the industrial process and environmental monitoring markets.

In the past, speciality gas suppliers and users have relied on electrochemical cells, gravimetric and other technologies to measure trace amounts of moisture in speciality gases in process streams. Gravimetric technology has provided excellent results, but can also be seen as slow, expensive and demanding of a great deal of expertise to operate.

Now, however, a new H2O moisture analyzer is available that uses tunable laser diode (TDL) spectroscopy to provide highly accurate and virtually instantaneous measurements of trace amounts.

Based on advanced NASA optical technologies, the new product could play an important role in industry. For the users of high-purity bulk nitrogen, hydrogen, dry air or other speciality gases, it is critical to stable operations that these gases are free of contaminants such as moisture.

Although electrochemical devices may initially perform with acceptable accuracy, the confidence level in their measurements soon depreciates due to drift, the inability to read high concentrations of moisture.

The system consists of a cell that the sample gas flows through, a TDL that emit’s a specific wavelength of light through the gas, an optical detector and software to analyse and deliver the results.

In effect, this new technology offers the best of both worlds in measurement as it affords accuracy and speed and does not become desensitized or the subject of drift over time.

1-Sep-07 10:00 AM

Laser Sensors for Trace Moisture Measurements in Olefins Product Streams

Alfred Feitisch — Sat, 01 Sep 2007 15:00:00 GMT

Trace moisture measurement has critical importance for many petrochemical processes such as Olefin production. The SpectraSensors SS2100 analyzer, which has been developed to measure trace moisture in Olefins product streams based on wavelength modulation spectroscopy is presented. A differential measurement scheme is employed to eliminate the interference from background gases (e.g. ethylene and/or propylene). Moisture can be accurately measured in the 0 ~ 3 x 10 ^-6range. A repeatability (3) of (5~10) 10^-8has been demonstrated for moisture detection in Ethylene and Propylene. An excellent repeatability (3) of (2~6) 10^-8has been successfully demonstrated for moisture detection in other hydrocarbons such as various Alkane. Demonstration experiments confirm the sensitivity and accuracy of the analyzer.

1-Sep-07 10:00 AM

Laser-based analyzer gives ultra fast and accurate measurement of trace moisture

Jennifer Soto — Mon, 06 Aug 2007 15:00:00 GMT

To users of high-purity bulk nitrogen, hydrogen, dry air or other specialty gases, it is critical to stable operations that those gases are free of contaminants such as moisture. Specifications for maximum moisture allowed are often as low as the parts-per-million and even parts-per-billion levels.

In the past specialty gas suppliers and users have relied on electrochemical cells, gravimetric and other technologies to measure trace amounts of moisture in specialty gases in process streams. Gravimetric technology provides excellent results, but it can be slow, expensive, and require a lot of expertise to run.

Although electrochemical devices may perform with acceptable accuracy at first, the confidence level in their measurements soon becomes low, due to drift, the inability to read high concentrations of moisture. There is a tendency for those sensor probes to become desensitized by the gas streams they are measuring.

Specialty gas manufacturers must certify the contents in ppm or ppb to their customers. This is why reliability of measurement is so important.

Now a new H2O moisture and analyzer technology is available that employs tunable laser diode (TDL) spectroscopy to provide highly accurate and virtually instantaneous measurements of trace amounts of a particular gas (H2O in this instance). By its nature, the TDL based gas detection method is not susceptible to aging affects, making its factory calibration a timeless constant. The result is a very low maintenance analyzer that does not require consumables or scheduled calibration.

In effect, this new technology offers the best of both worlds in measurement: accuracy and speed.

Developed by SpectraSensors (Rancho Cucamonga, CA), TDL-based analyzers have revolutionized the measurement of gases in petrochemical streams such as natural gas. The technology employs a simple measurement that uses a fundamental principle: Molecules vibrate when excited by light at specific wavelengths. Therefore, if you can detect how much light is absorbed at these wavelengths, you can precisely measure the concentration of a given gas.

The system consists of a cell that the sample gas flows through, a tunable laser diode that emits a specific wavelength of light through the gas, an optical detector, and software to analyze and output the results.

The technology, widely considered a new standard in trace gas measurement, is extremely fast and the results are highly reliable. Furthermore, this "TDL" sensor does not become desensitized or drift over time.

6-Aug-07 10:00 AM

New Laser Technology Gives Ultra-Fast Moisture Detection During LNG Liquefaction

Jennifer Soto — Sun, 01 Jul 2007 16:00:00 GMT

A New Tunable-Diode Laser Analyzer Technology Helps to Prevent Catastrophic Ice Formation in LNG Liquefaction

The presence of even trace amounts of H2O moisture of CO2 can threaten the integrity of processing equipment during compression and liquefaction of the natural gas due to ice formation. While CO2 can be leading indicator of H2O or vice versa, in any case, it is essential to have very fast detection to improve the life of the desiccant while maintaining product quality.

In the LNG liquefaction process it is desirable to extend the life between regeneration of the mole sieve or to monitor performance of a glycol or amine contactor while avoiding contamination to the natural gas. This is done by checking the output of the bed or column in order to determine the breakthrough point (the exact point at which the concentration of H2O or CO2 rises), which indicates that the desiccant is saturated.

Now, a new H2O moisture and CO2 analyzer technology is available that employs tunable diode laser (TDL) spectroscopy to provide highly accurate and virtually instantaneous measurements of trace amounts of particular gas (H2O or CO2 in this case). By its nature, the TDL-based gas detection method is not susceptible to aging effects, making its factory calibration a timeless constant, the company said. The result is a very low maintenance analyzer that does not require consumables or scheduled calibration.

Developed by Rancho Cucamonga, California, USA based SpectraSensors, its TDL-based analyzers employ a simple measurement that uses a fundamental principle: molecules vibrate when excited by light at specific wavelengths. Therefore, it you can detect how much light is absorbed at these wavelengths, you can precisely measure the concentration of a given gas.

The system consists of a cell that the sample gas flows through, a tunable diode laser that emits a specific wavelength of light through the gas, an optical detector, and software to analyze and output the results.

In the past, LNG and NGL gas processors have relied on surface-based analyzers such as electrochemical and quartz crystal cells to measure trace amounts of moisture in process streams. Although these devices may perform with acceptable accuracy at first, the confidence level in their measurements soon falls due to drift, the inability to read high concentrations of moisture, and the tendency for their sensor probes to become desensitized by the gas streams they are measuring. Such situations have led to excessive maintenance and high operational costs.

The technology, widely considered a new standard in natural gas measurement, is extremely fast and the results are highly reliable, according to the company. Changes in gas concentrations during dehydration can be seen immediately, without the wet-up and dry-down delays that occur with traditional moisture analyzers. Furthermore, this “TDL” sensor does not become desensitized or drift over time.

1-Jul-07 11:00 AM