April 25, 2013

Conductivity standards below 100 µS/cm

 

The call comes in on a regular basis … “My process conductivity does not match the lab … help!”

GE DIGITAL CAMERAUsually this is followed by a conversation about the instrumentation not working. However, rarely is the instrumentation at fault. After checking temperature calibration, slope and offset, and cell constant settings the instrumentation is shown to be operable and fully functional. The problem: using commercially available standard solutions is not a good method of calibrating conductivity below 100 µS/cm.

There are a number of reasons that this method is prone to failure: instability and inaccuracy of the standards, temperature variation, and instability of samples themselves. The article “Is There an Accurate Low-Conductivity Standard Solution?” goes into great detail about the accuracy of the method typically employed for calibrating conductivity – a method that is sorely inadequate for low level measurements. However, there is a solution which is also explained in this article.

shutterstock_401691.artThe solution incorporates the Model CVU Conductivity Validation Unit designed by Rosemount Analytical to meet the critical calibration needs of the life science industry. The same solution lends itself to resolving discrepancies between labs and process in power, chemical and refining and a host of other industries that utilize low conductivity water for boilers, steam generation and process feed.

What is your experience with conductivity measurement?

April 10, 2013

Geothermal Power Plants Present Unique Safety Monitoring Challenges

Hello, this is Mauricio Romero, Latin American Business Development Manager for Emerson Process Management, Net Safety. In this blog post I’m going to outline challenges related to flame and gas detection within Geothermal power plants. Geothermal energy is a nonconventional supply which has many advantages. It is completely renewable, requiring only naturally present water and is continually replenished by heat generated from the earth’s GeoTherm_plantcore. There are very few, if any, by-products from the resulting steam, so the process is very clean and is of course a completely domestic energy source. With the cost and efficiencies associated with geothermal energy production beginning to match that of traditional power sources, more utilities and other companies are finding ways to take advantage of this resource.

Perhaps one of its few limitations is that the steam generated in many cases cannot be used as the primary driver for turbines, because it is not hot enough to flash on its own and water droplets can cause serious damage to mechanical components of the turbine. One good way to resolve this is by using a binary cycle concept design that uses hot water from the geothermal sources and a fluid with a much lower boiling point than water that is heated by the geothermal source – the steam from this liquid is then used to drive the turbine.

One of the best options for this application is pentane, which has a much lower boiling point than water. One huge disadvantage is that it’s extremely explosive, and even more so when converted into an absolute gaseous state.

In order to create a safe environment a reliable detection solution must be put in place to monitor the plant area for any potential pentane gas leak that can develop into an very serious condition if ignition was to take place. Normally these plants are located in remote areas, so detection technology must be very robust with minimum maintenance requirements, and power consumption has to be well monitored in order to avoid wasting the valuable energy generated onsite.

Installing Emerson Process Management, Net Safety detection solutions has proven to be an effective way to monitor potential hazards in this type of installation. Either catalytic bead sensor or infrared sensor technology can be used to monitor gas leaks of hot pentane, which happens to be a very heavy gas, making it extremely dangerous. Some alarms can be configured to provide early warning of dangerous concentrations of pentane in the environment, which can be used to alert personnel by means of signaling devices such as strobes or horns. This early detection will allow plant operators to proceed with effective measures that can range from isolating the environment, inspecting the area to visualizing points of pentane leakage. If a gas release results in a fire, optical flame detectors such as UV/IR or IR3 technology will be ready to respond instantly. Fast and accurate notification from flame detectors will also allow personnel to proceed with effective emergency response, potentially from remote locations, so time is of the essence in these circumstances. It may involve releasing of extinguishing systems to protect property, partial or total shutdown of the plant to minimize consequences, and evacuation of any personnel in the facility.

Net Safety detection technologies have proven to be an optimum solution overall in this application, due to a combination of highly robust construction that can resist the most challenging plant conditions and extreme environments, the lowest possible power consumption for fixed detection devices, with intuitive designs and special features that make Net Safety instruments highly reliable, user friendly and low maintenance.

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