April 16, 2018

Reduce False Alarms by Matching Flame Detection Technology to Your Application and Environmental Requirements

By Udi Tzuri, Director of Product Management, Flame & Gas Detection, Emerson Automation Solutions

There’s no perfect flame detection system for every application. Matching optical flame detector options – including single wavelengths of UV and IR, integrated UV/IR sensors, and more advanced units that offer triple wavelength IR sensors – to your requirements is everything. If you understand the type of flame to be detected, the environmental conditions surrounding the installation, and the required performance, the choice of flame detection technology becomes easier and the potential for false alarms is decreased.

Almost all flames produce heat, carbon dioxide, carbon monoxide, water, carbon, and other products of combustion, which emit visible and measurable UV and IR radiation. These same emissions from non-flame sources cause nuisance false alarms and plant shutdowns. There are two basic types of these emissions: natural sources including rain, lightning, and sunlight; and man-made sources including artificial light sources, welding, and radiation from heaters and machinery. All types include solar-blind UV; window contaminates; non-modulated IR; and modulated IR sources.

Energy that is constant over time or varies at an extremely slow rate like the IR energy emitted from heaters, lamps, and heat from the sun are described as non-modulated sources of radiation. Additionally, there’s a small amount of IR radiation emitted from all objects which is constantly present in any detector’s field of view. As a result, the majority of flame detectors are designed to only detect modulated IR radiation sources – a key characteristic of flames. Still, the detection isn’t straightforward. False sources include heated emissions, moving lights, signals, or combinations of non-modulating sources being altered by objects moving back and forth in front of them in between the source and the sensor (e.g., vehicles, personnel, or fan blades). This is overcome by the use of multi-bands which can distinguish on the IR spectrum between flames and other sources of radiation.

Outdoor applications must contend with the visible range of sunlight, which covers 0.3 to 0.8 microns. UV detectors generally detect energy below solar emissions (0.185 to 0.260 microns) and can be a suitable choice for outdoor applications because of their extremely fast response and wide field of view; but UV/IR and triple IR options offer higher immunity to potential false alarms from high-energy bursts from reflective surfaces. Safety engineers must also consider the source of the fire when selecting a detector. If the fuel could potentially be hydrogen-based, for example, a specially tuned detector is required. For hydrocarbon-based fires from fuels such as methane and gasoline, multi-spectrum IR detectors are typically the best choice.

Window contamination will negatively affect the detector’s performance and can cause the instrument to go into fault mode. Water droplets, condensation, snow, and ice are powerful absorbers of IR energy that can be delivered in random scales and intensity and are a well-known source to trigger false alarms or faults when combined with modulated energy sources like direct sunlight. UV radiation is also easily absorbed by a range of oils, smoke, carbon, and specific gases. Engineers need to be aware of the presence of vapors such as hydrogen sulfide, benzene, ammonia, ethanol, acetone, and others when selecting a flame detector for their application.

By analyzing your application for these types of potential false alarm triggers, you can let your flame detection expert know all the parameters for an optimal detector selection. If you’re experiencing a lot of false alarms, this may be a good time to review your choice of flame detection technology.

What kinds of problems do you experience with false alarms?

March 27, 2018

Maximize Your Gas Chromatograph’s Efficiency and Performance – Free Rosemount 370XA Gas Chromatograph Introduction E-Course

By Bonnie Crossland, Product Manager, Rosemount Gas Chromatographs, Emerson Automation Solutions

Knowledge is key to maximizing the capabilities of your Rosemount™ Gas Chromatographs (GC). Understanding how to properly operate and maintain your GC will help increase uptime, reduce maintenance costs, and extend asset life.

Regardless of your experience level, the Rosemount gas chromatograph online course will provide the knowledge and expertise you need to ensure your operations run as safely and efficiently as possible. This free e-course will provide attendees with a basic understanding of the 370XA gas chromatograph and will cover:
370XA gas chromatograph training preview

  • Capability and hardware
  • Installation and startup
  • Local operator interface (LOI)
  • Auto Valve Timing and Analysis Cycle
  • Calibration
  • Maintenance
  • Data Output and Chromatograms

 

SIGN UP FOR THIS ONLINE COURSE HERE!

Normally, this e-course is valued at $100, but for a limited time, you can sign up for free.

370XA gas chromatograph maintenance

Plus, if you complete this e-course and take our short survey by June 1, 2018, you’ll be eligible for 15% off your next Rosemount course, including any online courses and hands-on courses at one of our Emerson training centers.

Emerson offers a wide range of both online e-courses and more in-depth, in-person, hands-on training classes on the theory, operations, and maintenance practices for analyzers and instrumentation. For more information on Rosemount’s full range of courses, browse our course catalog, or view a calendar of our instructor-led courses at our training centers in Houston, Minneapolis, and Charlotte.

Register today for the online 370XA gas chromatograph course – a flexible, engaging, convenient way to learn about our GC technologies and solutions and how you can maximize the benefits it offers your plant.

March 6, 2018

Dissolved Oxygen and Ozone: Just the Facts

 

By Michael Francis, global product manager, Emerson Automation Solutions

As part of our continuing series answering frequently asked questions from customers, here are some important basics about that water industry workhorse, the dissolved oxygen and ozone analyzer.

Q. How do dissolved oxygen/ozone sensors work?
A. 
Dissolved oxygen and dissolved ozone sensors are amperometric sensors with a gas-permeable membrane stretched tightly over a cathode. A silver anode and an electrolyte solution complete the internal circuit. During operation, oxygen or ozone diffuses from the sample through the membrane to the cathode. A polarizing voltage applied to the cathode converts all the oxygen entering the sensor to hydroxide ions. The reaction produces a current, which the analyzer measures. The current is directly proportional to the rate at which oxygen/ozone reaches the cathode, which is ultimately proportional to the concentration of oxygen/ozone in the sample.

Q. Why are dissolved oxygen measurements necessary?
A. 
Dissolved oxygen is very important in the treatment of domestic wastewater, as well as industrial waste from such sources as the food, pulp and paper, chemical, and metals industries.

The primary function of dissolved oxygen in a waste stream is to enhance the oxidation process by providing oxygen to aerobic bacteria so they will be able to successfully perform their function of turning organic wastes into their inorganic byproducts, specifically, carbon dioxide, water, and sludge. This oxidation process, also known as the “activated sludge process,” is probably the most popular and widely used method of secondary waste treatment today and is normally employed downstream of a primary settling tank. The process takes place in an aeration basin and is accomplished by aeration (the bubbling of air or pure oxygen through the wastewater at this point in the treatment process). In this manner the oxygen, which is depleted by the bacteria, is replenished to allow the process to continue.

In order to keep this waste treatment process functioning properly, a certain amount of care must be taken to hold the dissolved oxygen level within an acceptable range and to avoid conditions detrimental to the process. It is also important to make the measurement at a representative location on a continuous basis to have a truly instantaneous measurement of the biological activity taking place in the aeration basin.

Q. What affects the accuracy of dissolved oxygen/ozone sensors?
A. 
Since the O2 and O3 sensors measure diffusion across a membrane, anything that affects the diffusion rate can make the reading inaccurate. Two major concerns are: 1) a coated membrane which slows down diffusion; and 2) inadequate flow which reduces the availability of fresh sample near the sensor tip.

The rate of diffusion of ozone through the membrane also depends on temperature, as this affects the membrane permeability. Rosemount Analytical dissolved oxygen and dissolved ozone sensors include a PT100 RTD sensor, which can measure the temperature and send it back to the analyzer for automatic compensation. If the temperature reading is not correct, the analyzer will signal an error.

Q. How to calibrate a dissolved ozone sensor?
A. 
Calibration is necessary to ensure measurement accuracy. It is recommended that you calibrate your equipment regularly – the more critical the data, the more frequent the calibrations.

Because ozone standards do not exist, the sensor must be calibrated against the results of a laboratory test run on a grab sample of the process liquid. Ozone solutions are unstable, so the sample must be tested immediately. Portable test kits are available from other manufacturers.

Q. How do I clean my dissolved oxygen/ozone sensors?
A. 
Periodic maintenance and cleaning is required for best performance of the sensor. Generally, the membrane and fill solution should be replaced every four to six months. Sensors installed in harsh or dirty environments require more frequent maintenance. When cleaning a dissolved oxygen or ozone sensor, do not rub or brush the membrane surface. Carefully rinse the sensor tip with water to remove surface coating. If that does not restore function, change the membrane cap and calibrate.

Do you have any tips on using dissolved oxygen optimally?

And come join the Emerson Exchange 365 Community to get real solutions to real-world problems and maximize performance, productivity, and profitability: www.emersonexchange365.com.

References

January 17, 2018

Take the Risk Out of Complex Analytical Systems Integration Projects

 

By Nouman Raja, director of Rosemount Analytical Solutions, North America, Emerson Automation Solutions

Integrated analytical measurement systems are often complex, costly, and have multiple stakeholders involved throughout all phases of the system’s integration project – from conception to commissioning. With so many factors to consider, including stringent specifications, thorough documentation, and tight deadlines to meet, any minor delay can cause a major setback and place your bottom line at risk.

Most industrial companies aren’t equipped to go into the systems integration business in order to meet their analytical systems’ needs. Emerson is! With a unique combination of analytical expertise, process knowledge, and global resources, Emerson is a single-source provider of complete analytical solutions for liquid and process gas applications including integration of third party analyzers. From sample handling systems and standalone instrumentation panels and cabinets, to three-sided shelters and environmentally controlled walk-in enclosures, Emerson offers wide flexibility in system packaging to meet project and application requirements.

Far from just nuts and bolts hardware, Emerson manages systems projects through the Project Management Office (PMO) where highly trained systems engineers take care of everything from Front End Engineering Design (FEED) and consulting services to manufacturing, integration and testing, to commissioning and on-going lifecycle support.

A new guide available HERE shows you how to stay on time and on budget, ensure project certainty and reduce risks. The guide outlines ways to –

  • ­Simplify the complexities of your project scope. Your designated project manager engages early to understand project requirements and align with your team to manage and control scope.
  • Avert risks and stay on schedule. The PMO collaborates with your team to identify opportunities for efficiency and risks, and implement mitigation plans to prevent possible schedule pitfalls. ­
  • Stay on task and on budget. It is the PMO’s responsibility to manage the budget and update you throughout the project, accounting for possible risks, changes in scope, and other possible situations which may impact the budget.

Download a copy of the guide HERE and get a better idea of how to take the risk and worry out of executing complex analytical systems projects. We also invite you to learn more about the Emerson advantage in systems integration by visiting Emerson.com/RosemountAnalyticalSystems.

And come join the Emerson Exchange 365 Community to get real solutions to real-world problems and maximize performance, productivity, and profitability: www.emersonexchange365.com.

January 4, 2018

Learn the Basics of Optimum Chlorine Analysis

By Michael Francis, global product manager, Emerson Automation Solutions

Let’s talk chlorine. Obviously, balancing chlorine in water treatment is a critical issue, so having a friendly relationship with your chlorine analyzers is important. Customers ask us a number of basic questions about chlorine and its analysis. Here are a few of these questions with the essential answers from our Rosemount Analytical experts.

Q. How do you measure chlorine in aqueous solutions?
A. 
Reagent-less chlorine measurement requires an amperometric sensor and an analyzer to convert the current signal to a ppm reading. Unless the pH never changes more than 0.2 pH units, a separate pH sensor is strongly recommended when performing chlorine measurement. The preferred installation is in a bypass line with the sensors installed in a low flow cell. Other alternatives are installation in a 1-1/2 inch tee or submersed in a tank.

Q. How do chlorine sensors work?
A. 
Amperometric sensors use electric currents or changes in electric current to detect ions in a solution. The amperometric sensor tip consists of a membrane stretched over a noble metal cathode. The chlorine in solution diffuses through the membrane to the surface of the cathode. A voltage applied to the cathode reduces the chlorine to chloride. This process consumes electrons, which come from a second electrode (the anode) inside the sensor. To measure the amount of chlorine in the solution, the analyzer measures the number of electrons consumed at the cathode (the current) which is directly proportional to the concentration of chlorine in the sample. Since the sensor is constantly consuming chlorine from the process, it is necessary to have a continuous flow in front of the sensor, or else all the chlorine in front of the cathode will be destroyed, and the sensor will read zero chlorine in the sample.

Q. What types of chlorine sensors are available for real-time measurement and process control?
A. 
Monochloramine, free chlorine, and total chlorine sensors and systems are available for process control. It’s important to match the application and kind of chlorine to the measurement system.

Q. How do I calibrate a chlorine sensor?
A. 
Because stable, diluted chlorine and monochloramine standards are generally not available, the sensor must be calibrated against the results of a laboratory test run on a grab sample of the process liquid. (Learn how to zero the Free Chlorine Measuring System with a Rosemount Analytical 499ACL sensor here.)

Q. What affects the accuracy of chlorine measurements?
A. 
Chlorine measurement accuracy can be affected by fluctuations in temperature as it changes membrane permeability rate, electrolyte conductivity, and the sample pH levels. The need for additional sensors is reduced with the automatic temperature compensation and low sample conductivity requirement on the Rosemount 499ACL (Option -01) free chlorine sensors. Click HERE to learn more about the Rosemount Analytical 499ACL Chlorine Sensor.

There are many more basic questions on chlorine measurement that can be critical to successful water treatment. If you have pressing questions, please comment below.

We’ll address some more chlorine questions in the future.

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