Hi. I’m Marc Mason, business development manager, and I’m happy to be your analytic expert today. You know the old saying, “You have to spend money to make money”? Well, in the water industry we’re finding that many water plants have to spend money to save money. Recently, Tom Johnson, water industry business development manager at Emerson, wrote an article for Water & Wastes Digest that talks about advanced technologies like radar leveling, Waste Water Art-2reagent-free liquid analysis, ultrasonic control, wireless measurement devices, advanced predictive diagnostics, and SCADA control systems, and how case histories are showing the cost savings that water treatment plants can garner from investing in emerging advanced analytical, diagnostics and measurement technologies, as well as the control systems that manage those technologies. The case history described in the article demonstrates this premise pretty clearly –

Taylorsville-Bennion Improvement District serves 70,000 people in approximately 14 square miles in the center of the Salt Lake Valley, Utah. The district has approximately 16,700 connections and 229 miles of water lines. For many years, it tried to keep its old chlorine and fluoride sensors and analyzers running by constantly rebuilding, recalibrating and replacing parts. While this seemed like the cost-effective thing to do, it was proving too much for the district’s small staff – a situation familiar to many managers. The units were laborious to rebuild and required replacement of two to three probes per year; plus, they used expensive membranes that were difficult to replace and often broke during installation. The district estimates that the cost to operate the old sensors and analyzers was approximately $9,000 per year at its three locations. The units required daily attention and annual rebuilds, adding labor costs to the equation.

When the district decided to replace the old sensors and analyzers with the latest technology, its situation changed drastically. The new systems were built to last three years, versus one year, and were known to be effective as long as 15 years. The new technologies were reagent-free, reducing costs and maintenance, and needed far less frequent calibration. Bottom line: the district now replaces the membranes and electrolyte of the chlorine systems for $150 per year, compared to more than $6,000 in maintenance costs for the old systems. While the new equipment was costlier to purchase, the dramatically lower cost of ownership is rapidly offsetting that differential – a situation that can apply to many technologies.

There are many other examples of cost savings quoted in the article. Click HERE to read it.

How about you? Have you invested in what seemed a costly technology, only to discover it saved money? We’d love to hear your story.

G’day y’all – Shane Hale here again from Gas Chromatographs. At the end of January, I had the honor of presenting at the Natural Gas Sampling Technology conference (NGSTech) held in New Orleans (they even have a photo of me speaking in 2008). This two-day conference focused exclusively on the latest developments and challenges in the field of natural gas sampling for both spot samples and online analyzers.

Fig. 1 – Calculating HCDP at pipeline pressure to provide an early warning of two-hase flow.

Just about every single paper presented at the conference mentioned the importance of the hydrocarbon dew point of the sample gas when designing or operating a sample system. (This being in New Orleans, there was even a suggestion to start a drinking game around the term!) My paper dealt with the issues that the hydrocarbon dewpoint of the sample can cause when using a gas chromatograph. I discussed how you can use the hydrocarbon dew point calculation in our C9+ gas chromatographs to calculate the hydrocarbon dewpoint at the pipeline pressure to provide an early warning of two-phase flow and avoid inaccurate flow measurement (see Fig. 1).

Fig. 2 – The effect on the energy value of the gas being measured when heavy components condense in the sample lines.

I then discussed the effect that poor sample handling can have on the analysis. I have a real-life example that I use all the time that shows the effect of the analysis when the heavy hydrocarbons drop out as the sample line temperature drops at nighttime (see Fig. 2). In this example, the heat trace was turned off.

And this is where it got interesting. I’m standing there on stage, in front of over 180 people, and an idea comes to me. We can calculate the hydrocarbon dew point at up to four pressures. The regulated sample pressure is controlled to around 20PSI G/1.4BarG. What if we calculate the hydrocarbon dew point of the sample at the regulated sample pressure, and compare this to the ambient temperature? If the hydrocarbon dew point is the same as (or very close) the ambient temperature, it means that the sample has dropped out some of the heavy components into the sample system. (see Fig. 3)

Fig. 3 – HCDP at the sample pressure tracking the ambient temperature, indicating the heavy components are dropping out in the sample lines.

If the heavies have dropped out, then the GC is no longer analyzing the same gas as what is in the pipeline. If the GC is not analyzing the same gas that is in the pipeline, then energy calculations and flow calculations will be incorrect, and thus the custody transfer measurement will be incorrect. This must have been a good idea, as the audience clapped at the end of my presentation, and quite a few people came up to me to discuss this in the exhibition hall later that day.

Wow. What a concept: online determination of the sample system performance. After the conference, I went back to my office and fleshed this out a bit. By entering the nominal regulated sample pressure into hydrocarbon dew point calculation as a fixed value, the C9+ Gas Chromatograph will provide the dew point of the gas in the sample lines. An ambient temperature transmitter can be connected to the analog inputs of the 700XA C9+ GC (for the Model 500, the second detector on the C9+ HCDP application uses the analog inputs) or the ambient temperature downloaded to the controller via modbus. A user calculation can then compare the values and if they are within a certain tolerance (e.g. 10°F), the controller can raise an alarm to highlight an issue in the sample system (for example, the heat-trace is turned off or not installed).

In practice, the comparison of the sample pressure hydrocarbon dew point and the ambient temperature is best done in the flow computer or the SCADA system, as they have better alarming and trending capabilities than the gas chromatograph, but the concept is the same. The ability of a C9+ gas chromatograph to calculate the hydrocarbon dew point on multiple pressures give us new online diagnostics to help us operate our custody transfer metering systems.

Do you think you could use this at your locations? Leave a comment here and tell us your thoughts. And if you’d like a copy of my paper, just click here.

’till next time,