GE Sensing: PT878GC Ultrasonic Flowmeter
Clamp-on flow measurement for large natural gas pipes

A Spanish gas distribution company recently built new recompression stations for delivering natural gas. Gas occupies a large volume and requires high pressure for pumping and transport to customers. Pressure drops due to long distances between the recompression stations and delivery points necessitated a nonintrusive method for monitoring the volume of flowing gas.

Although the customer purchased a competitor’s product, engineers from GE Sensing were confident that their technology would make measurements for the customer’s applications more reliably. They requested the opportunity to demonstrate GE’s Panametrics ultrasonic, clamp-on gas flowmeters. The customer agreed, and GE installed its portable PT878GC clamp-on gas flowmeter on a 24-inch (600 mm) carbon steel line with a 1⁄2” (12.7 mm) pipe wall at one of the recompression stations. Measurements were within 2 percent of an orifice plate meter, and most were below 0.5 percent error with an average deviation of 0.2 percent.

To ensure customer satisfaction, GE conducted a second demonstration on 30- and 36-inch pipes, which also delivered successful readings. Both pipes had a 0.28-inch (7mm) polyethylene (PE) coating on the outside. For the 30-inch pipe, GE obtained the best results with a 500 kHz transducer in a two-traverse configuration over the PE liner. Engineers left the PE jacket in place as it dampened undesired surface waves in the pipe wall, which could cause the meter to read incorrectly. For the 36-inch pipe, 250 kHz transducers deployed in a single-traverse configuration delivered the best results.


Dwyer Instruments: Digihelic Differential Pressure Controller
Power plant upgrades emissions control process

A power company is using the Digihelic differential pressure controller at one of its generating stations — a coal burning power plant. Due to environmental compliance issues many power companies are being asked to control NOx emissions. NOx is a combustion-generated gas that consists of nitrogen oxide (NO) and nitrogen dioxide (NO2).

One control method currently used when combusting solid fuels, such as coal, to reduce NOx emissions is called SCR (selective catalytic reduction). This is a post-combustion process that can reduce emissions by 50-60 percent. The SCR system being installed uses ammonia to perform the NOx reduction. The power plant’s method of ammonia injection utilizes an ammonia injection grid with 33 individual valves.

The ammonia is injected into an air stream moving between 350-500 SCFM. An averaging Pitot tube is used for flow measurement and the Digihelic computes the SCFM from the averaging Pitot’s differential pressure signal. The Digihelic computes airflow output, via its RS-485 communications, which is then transmitted wirelessly to a computer lab running a software package that adjusts each of the 33 valves for balance control.


Endress+Hauser: Proline Promass F 10-Inch Sensor
Coriolis system for natural gas fenceline measurement

The Promass 83F 10-inch Coriolis mass flowmeter was the solution of choice for a major global chemical company conducting a fenceline measurement for natural gas. This measurement used to be done with an orifice run over multiple years. Promass 83F 10-inch caught the company’s attention though, as Coriolis technology was already successfully used in other applications, but was so far not available for the large pipe sizes and higher flowrates required to match the needs of this application.

The Promass 83F 10-inch not only met the pipe size and flowrate requirements of the application, but also provided a specified accuracy of +/-0.35 percent of reading for natural gas and an increased turndown by more than a factor of 10 over the previous system, calculating to a monthly savings of several thousand dollars for the chemical company.


Kayden: Classic Flow/Level/Temperature Switch
Natural gas flare stack or rupture disc early warning

The customer needed a flow/no-flow switch with tight tolerances for leak detection. What made this application particularly challenging was that to function successfully the flow switch needed to have the sensitivity and repeatability to react predictably to a very small increase in flow, such as a slight gas leak. Additionally, the electronics and sensor needed to be robust to withstand the physical shock of a full release through the stack.

In this application, the Kayden Classic 810 thermal-dispersion flow/level/interface/temperature switch functions as a flow/no-flow indicator. The main relay contact is wired for normally open operation. After the range is set for flow and gas, the setpoint is configured to trip the relay when the thermal signal is below setpoint.

In this way the switch will provide a continuous electrical output through the relay contact when the switch is in a no-flow state. When gas is released, the thermal signal increases above setpoint and the relay contact opens, generating an alarm condition. Likewise, with a loss of system power, or if the Kayden switch is taken off line, the relay contact opens and an alarm is generated.


KROHNE: OPTIFLEX Radar Level Gauge
Noncontact level measurement for harsh environments

Air Liquide, a leading producer of industrial and medical gases, selected the KROHNE OPTIFLEX level meter to replace load cells for measuring levels of CO2. The OPTIFLEX was chosen due to its ability to operate in extreme temperatures down to -20 C when the tank was being filled at a pressure of 20 bar. Measuring operations start immediately after the valve is opened. According to Air Liquide, the OPTIFLEX indicated the correct level even when interfaces formed as a result of different CO2
densities.

The OPTIFLEX has higher signal dynamics, which translates to accurate and stable measurements. Despite disturbances, such as strongly agitated surfaces, the OPTIFLEX can clearly locate the product’s true surface and provide accurate measurements.


Philadelphia Mixing Solutions: Opti-Con Controller
Aeration process optimization and control for wastewater treatment

Since two-thirds of the power consumed by wastewater treatment plants is devoted to the aeration process, the Opti-Con controller aims to provide complete control over energy usage by the aeration equipment while managing the biological treatment process.

The philosophy behind the creation of the Opti-Con controller system is to take advantage of the varying loads and flows during a day, often referred to as the diurnal curve. Essentially, this curve depicts the demand for biological control over time. First-generation systems waste large portions of power due to being set at a specific level. This is often an operation average that ensures the permitted level of effluent is met. The Opti-Con, on the other hand, constantly monitors the real-time characteristics of these aeration basins to meet the influent demand. By following the diurnal curve’s ebbs and flows, the process power is utilized only when required, turning down aerators to take full advantage of power saving potential.


Rosemount: 3051S Ultra for Flow Transmitter
Providing improved accuracy and wider flow turndown

A large manufacturer of industrial gases implemented the 3051S Ultra for Flow transmitter at its metering sites that are used for billing delivered product, including Syngas, oxygen, hydrogen, nitrogen, etc. By implementing 3051S transmitters with Ultra for Flow performance, the manufacturer was able to achieve 1 percent metering accuracy at 10-to-1 flow turndown with a single DP transmitter. Previously, two transmitters had to be stacked to be able to achieve the level of performance required. The customer estimates it saved over $2,500 per installation in capital cost and at least one hour per year in calibration time.

An OEM providing extruders to customers in the food and feed processing industries used the 3051S Ultra for Flow on systems where steam injection rates were too small to measure accurately using conventional technologies. This OEM purchased Ultra for Flow as part of a complete flowmeter solution, eliminating impulses that were causing erroneous flow readings as the wet leg heights changed. The integral assembly also provided simplified installation and startup.


Spirax Sarco: Pivotrol Pump
Eliminating waterhammer in pressure-powered condensate system

A textile plant had used pressure-powered condensate pumps for many years. After a few years of service, a duplex pump package began to have constant problems. As the pumps failed, the condensate would begin to back up in the piping, causing waterhammer.

Pivotrol Pump retrofit mechanisms with PowerPivot technology were installed in the pump bodies. Upon startup, the pumps were noted to be operating at six cycles per minute, normally too high a cycle rate to provide reliable service. Immediately the maintenance staff checked the pumps to ensure correct operation. After four months, there were no repair orders, banging of pipework, or flooded pipes. Six months, a year, then 18 months passed — the Pivotrol pumps still ran strong, and the condensate noises disappeared for good.


Yokogawa: Admag AXF Magnetic Flowmeter
A new approach for monitoring electrode buildup

Yokogawa’s AXF Series of Admag magnetic flowmeters features electrode-coating diagnostics, which allows users to monitor the status of electrodes in real time and schedule maintenance before the electrodes coat to the point where the measurement is interrupted or significantly degraded.

ADMAG AXF’s electrode-coating function can provide a visual indication of the coating via a four-segment display. The coating level is determined by applying a small square wave current between the electrodes and the earth rings. The current pulses are coordinated with the coil excitation pulses so as not to interfere with the flow measurement. As the coating increases and the resistance in the electrode/earth ring circuit increases, the number of segments shown in the bar graph also increases. At any point in time, the user can go into the AXF’s software and directly read the resistance values seen by the magmeter. Users can also change the resistance setpoints for the electrode coating function if they need to be fine tuned for a specific application. If desired, the status output can be configured so that a contact closure will be provided when the third segment lights. When the fourth segment lights, an alarm function is activated, indicating that there is an issue that needs to be addressed.