The new Rosemount™ 6888C In-Situ Oxygen Analyzer can help you lower energy consumption and costs while minimizing emissions resulting from combustion processes. The robust Rosemount zirconia sensing cell features an acid-resistant option with catalytic beads to increase cell lifetimes in the presence of sulfur and other poisoning agents in flue gas.
The latest addition to the Rosemount 6888 portfolio can be configured as a blind, stand-alone transmitter with HART® or FOUNDATION™ Fieldbus communications, or with the Rosemount 6888Xi or Oxymitter remote electronics, or with an Emerson™ Wireless 775 THUM™ Adapter. The Rosemount 6888 analyzer is known for being simple to install, commission, and operate, and features a variety of calibration options. Calibrations can be performed manually, semi-automatically, or automatically. Semi- and fully-automatic calibration requires the use of a Rosemount IMPS 4000 or SPS 400 1B accessory or by ordering the integral autocalibration option. Additionally, the Rosemount 6888 portfolio provides industry-leading accuracy of ±0.75% of reading or ±0.05% O2, whichever is greater.
Gas chromatographs perform critical measurements in a wide range of process and natural gas industries. In many applications like natural gas production and custody transfer, these measurements translate directly into profitability, process efficiency, and regulatory and contract compliance. That’s why optimizing the performance of your GC can have a big impact on your bottom line.
To help users get the most from their GC over the course of its lifecycle, Emerson is offering a free webinar series that brings together our GC experts to offer trusted insights and best practices. The webinars will also provide answers to most frequently asked questions and solutions to challenges operators may be facing in the field. The first webinar in the series is coming right up –
WEBINAR 1: GC’s Response Factors and Why They Are Important
Tuesday, May 1, 2018
10 AM – 11 AM CDT (Houston)
Emerson’s GC expert, Bonnie Crossland, will discuss the importance of GC’s response factor. Understanding how a detector responds to the measured components can provide an effective way to validate the correct operation of your gas chromatograph. Changes in the detector’s response to the measured components can indicate changes in the analysis that might cause inaccurate measurements.
This webinar will review the elements that can cause variations in a response factor, and how those variations can be used to help troubleshoot the gas chromatograph.
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.
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:
Normally, this e-course is valued at $100, but for a limited time, you can sign up for free.
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.
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.
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.