The KPI scrubber is a magnesium hydroxide system. The pH measurement is installed after neutralization and the wastewater includes many magnesium sulfate solids. The flow chamber was sometimes clogged with solids.

KPI had been using a pH sensor with a water jet cleaning system. The cleaning system, however, was ineffective against solids that coated and plugged the glass and liquid junction of the sensor. After a few days of operation KPI could no longer trust the pH values being received as the readings would fluctuate significantly. Even when the sensor was cleaned manually, a time-consuming and expensive process, the pH sensor had to be replaced every month.

As a result, KPI often had to control the dosing of magnesium hydroxide manually based upon the experience and intuition of the operators. In addition to the cost, personnel time and extreme inconvenience, the plant was faced with significant local regulations regarding emission of SOx. If the manual control led to low magnesium oxide dosing, a SOx emission could occur with subsequent fines. If the dosing was too high, the costs of the expensive magnesium hydroxide soared and increased costs.

On top of all this, the pH sensor KPI had been using was connected to an analog device which made it impossible to get sensor status from the instrument automatically. The company could not predict sensor failure or receive other data without manual intervention.

With good reason, KPI was looking for a method of applying automatic control to its set points based on reliable pH measurement.

KPI switched their pH analysis to the Rosemount Analytical Model 1056 using the PERpH-X 3300HT-10-30 with SMART pre-amp as a sensor. The PERpH-X sensors are designed with an enhanced double junction reference that is specific to extreme applications. Reference flow into the process stream is controlled using a porous Teflon® junction that can be replaced in the event of fouling or plugging. The specially designed junction is chemically resistant and has a large surface area to maintain a steady reference signal in dirty or oily applications. This reference also resists poisoning which can occur with other sensors as a result of the diluted hydrochloric acid used to manually clean the sensor during preventive maintenance.

The 3300 has been able to operate accurately for two to three weeks before manual cleaning and the sensors are able to be used more than nine months in the process as KPI also takes advantage of the rebuildable reference feature of the 3300. The 3300 has lasted nine times longer than the previously used sensor – a dramatic improvement saving time and money.

The HART-enabled pH measurement by the 3300 allows KPI to monitor other valuable information such as reference impedance, glass impedance, temperature, etc. By monitoring these sensor parameters, KPI could detect a sudden large deposit of the reference impedance. Figure 1 shows the increasing reference impedance trend as well as the result of a sudden deposit. This information is used by KPI to improve the timing of maintenance. They are also able to use temperature data to determine clogging of the flow chamber which saves both maintenance costs and prevents shutdowns. Using the Emerson 1056P-HT with a 3300HT sensor with the SMART pre-amp and jet sprayer, KPI has been able to control the dosing volume of magnesium hydroxide automatically saving time and improving efficiency. While savings in actual product costs measures in the thousands of dollars, the value of the accurate measurement is incalculable.

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

Usually 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.

The 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?

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 core. 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.

The traditional method of determining the hydrocarbon dew point online is to use a chilled-mirror device that reduces the temperature of a mirror in a measurement chamber filled with the natural gas until enough hydrocarbon mist condenses on the mirror to be detected. Other dedicated HCDP analyzers using different measurement techniques are also available; however, they all provide a HCDP only at a single pressure and are dedicated analyzers that provide a single measurement.

An alternative to a dedicated HCDP analyzer is using an equation of state (EOS) to calculate the hydrocarbon dew point at any pressure from the composition obtained from a gas chromatograph (GC). By entering the composition of the natural gas into a recognized equation of state, the theoretical HCDP can be calculated for any pressure as well as the cricondentherm (the highest dew point temperature at any pressure). The validity of the calculated value depends on the accuracy of the composition used especially for the higher carbon number hydrocarbons (C6 to C9).

Gas chromatographs are already used in custody transfer measurement to determine the energy content, compressibility, density, and other physical properties. Therefore, using a gas chromatograph to determine the HCDP using an EOS provides additional valuable information from already required equipment.

To learn how the C9+ gas chromatograph can be used to calculate hydrocarbon dew point at any pressure allowing pipeline operators to take corrective action before heavy hydrocarbons enter the network, click HERE. And let us know if you’re using, or have considered using a gas chromatograph at your plant!

As you know, many different pathogens (bacteria, viruses and parasitic protozoa), some of which are potentially lethal, can be found in both surface water and some groundwater sources. Disinfection is integral to ensuring water quality and safety. Large-scale use of chlorine for water disinfection began in the U.S. in 1908, and chlorine is now used in both primary and secondary disinfection steps at many water treatment plants. However it has been reported that trihalomethanes and haloacetic acids are produced as byproducts of the chlorination process, and that these byproducts could be hazardous. Ozone also can produce byproducts, bromates, and much study about safe levels is being conducted.

In response to these reports, many water utilities have begun examining alternatives to chlorine for primary water disinfection, two of which are monochloramine and ozone. We will discuss ozone in this blog.

The first drinking water plant began operations in Nice, France in 1906. Since Nice has been using ozone since that time, it generally is referred to as the birthplace of ozonation for drinking water treatment. Today, some U.S. water plants are moving to ozone for disinfection to address more stringent drinking water regulations. Ozone is a powerful oxidant. Its effectiveness is measured by the amount of residual ozone remaining. The presence of a small residual implies that all organic compounds have already been neutralized.

Adding ozone to bottled water is a way to ensure that the water in the bottle is free of microorganisms, without leaving trace disinfectants.  When diffused into water, ozone oxidizes organic material, including waterborne microorganisms. It’s more effective than chemical disinfectants like chlorine and is both odorless and tasteless.  Because of ozone’s short half-life, any bottled ozonated water will have little or no remaining ozone in the solution.  It will have received an effective disinfection prior to bottling which will leave no residual disinfectant.

Ozone gas is produced by electrical discharge in air. The gas is injected into a contact chamber via diffusers to distribute the gas evenly and speed the disinfection process along. The ozone concentration in the contact chamber, where reaction is still occurring, can therefore be much higher than in the final effluent. Some ozone generator manufacturers recommend monitoring ozone concentration in the contact chamber to meet disinfection requirements. Aside from the capital cost of the ozone generator itself, the main cost of an ozone system is the electricity used.

Have you used or considered using ozone for water treatment? What was your experience? We’ll be happy to talk with you about the effective use of ozone in your water treatment or bottling plant – just let us know!