Sentry Equipment Corp., located in Wisconsin,

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1 Sentry Equipment Corp., located in Wisconsin, USA is widely recognized for manufacturing systems used to condition power plant water and steam samples. Sentry systems ensure integrity of the samples while enabling analytical measurements to be reliably made after conditioning the sample temperature, pressure and flow rate. The company relies on Mettler-Toledo Thornton instrumentation for providing accurate sample measurements. Thornton sensors and transmitters monitor specific cation and degassed cation conductivity, ph, ORP, dissolved oxygen and total organic carbon, which are typical of measurements made with the help of Sentry sample systems. Sentry conditioning systems are used in fossil fuel and nuclear power plants to validate and monitor water and steam samples. Sentry has equipment installed in virtually every power plant in the USA and in many power plants throughout the world. Sentry Equipment has been a leader in developing sample conditioning components including variable pressure reducers rated up to 345 bar (5,000 psi), single tube sample coolers and sample sequencing controllers. In addition to water and steam sampling, Sentry is also a leader in process sampling of gases, liquids, slurries and bulk solids. Sentry finds the multi-parameter capability of Thornton transmitters of particular significance in their water sampling panels. These transmitters allow up to four analytical parameters plus sample tem-

2 j j j perature to be measured, displayed and re-transmitted from a single instrument. This concept works well for cycle chemistry monitoring of key parameters on a single sample stream. It also allows greater functionality such as computing ph from specific and cation conductivity and comparing the result with a ph electrode measurement for backup. All of this is accomplished in a single transmitter with common display, operator interface and output signal type. In the past decade, the Thornton 770MAX transmitter has provided multi-parameter capability successfully to support the Sentry Equipment partnership. The 770MAX is widely used in cycle chemistry monitoring and makeup water treatment systems. The next generation multi-parameter transmitter recently introduced by Thornton, the M800, features a color touchscreen display with predictive maintenance, online sensor diagnostics, and Plug and Measure input for all parameters see sidebar. According to Mike Farrell, President and CEO of Sentry Equipment Corp., As new challenges arise in evolving power cycle chemistry treatment and control, Sentry Equipment and Mettler-Toledo Thornton will continue working together to provide optimal cost-effective measurement solutions. Discover more at: c c

3 Transmitter Configuration Tool (TCT) software is included with most Thornton transmitters. This PC-based program enables users to configure the transmitter and download, upload, save or print configurations specific to their applications using a USB port on the transmitter connected to a PC or laptop. This functionality exclusive to Thornton can save considerable time and effort when setting up multiple transmitters with custom configurations, repeatably, time after time. Once a configuration file is created, TCT software permits a user to upload it to all transmitters using any PC or laptop computer, eliminating all configuration at the keypad and thus greatly reducing setup time. Separate application configurations can be saved and uploaded from a library of previously developed configuration files. In addition, with the TCT, data can be logged and reviewed at the computer and stored in Excel files for review, troubleshooting or graphing at a later time. Convenience: If a process engineer needs to configure ten transmitters with identical settings, at an average of minutes each, the potential for error or inconsistency is considerable. However, once a file is created on a PC, TCT software enables the user to upload it accurately to each transmitter, either in a central location before installation, or after mounting on the water system. Flexibility and consistency: Multiple configurations may be stored for future use. For example, a configuration for a reverse osmosis / deionization application may include many conductivity, ph, TOC and flow sensors connected to a single transmitter. All measurement range settings and limits, alarms, outputs, etc. can be set and saved for this specific application, while another variation using different sensors or settings can be configured and saved separately. These custom applications can be pre-configured and loaded to transmitters whenever they are needed. Security: TCT software serves as a security backup to save application-specific configurations in a library folder on a separate computer for future use, in the unlikely event the configuration is inadvertently altered or deleted, or the transmitter is replaced. j Ensures consistent configuration of several transmitters with the same settings j Saves time individually configuring multiple transmitters j Saves time uploading applicationspecific configurations from the user- developed library j TCT software is bi-directional data may be transferred from PC to transmitter and vice-versa j Transmitter configuration can be completed at a convenient time and location even remotely or in an office j Enables real-time data collection j Data can be logged and reviewed at a computer and stored in Excel TM files for review, troubleshooting or graphing For further information about TCT software, contact your local Mettler-Toledo Thornton sales office or visit: c

4 Ecolutia Services is a global provider of mobile water treatment solutions to industrial and municipal customers. As a part of the Stulz H+E group, Ecolutia Services operates the world s newest and most efficient fleet of mobile water treatment systems for process water, wastewater and ultrapure water treatment. Water flow capacities range from 1440 to 7200 cubic meters per day (380,400 to 1.9 million gallons per day). The global increase in demand for water is a driver in products developed by Ecolutia Services and its sustainable approach to water treatment. Customers can benefit from solutions to drought-proof supplies, reuse water, recover and treat wastewater, all while using products with greater productivity, greater efficiency, lower logistical costs and lower energy consumption. Many customers have found that outsourcing water treatment on a temporary or even permanent basis enables them to concentrate on their core business. They no longer have to be concerned with the handling of pre-filtration treatment chemicals, cleaning agents for reverse osmosis, acids and bases used to regenerate deionizers or reagents needed for waste neutralization. Customers are also relieved of responsibility for the day to day operation and expertise needed to optimize a treatment system for varying raw water conditions. In addition, customers generally pay only for treated water consumed, rather than for direct costs of building and installing the treatment system. Typical applications include: j Emergency water supply j Start up and plant commissioning j Planned or unplanned maintenance outages j Condensate recovery and polishing j Treatment of alternative water supply Industries served include: j Power j Chemical j Semiconductor, Microelectronics j Pharmaceutical and Life Science j Food and Beverage j Oil and Gas j Pulp & Paper, Mining, Municipal and other water systems

5 The Ecolutia water treatment systems are designed to treat a wide range of raw water from sources such as surface reservoirs, to brackish or seawater, to industrial wastewater. Quality can vary depending on the project location and water availability. To achieve the desired quality, volume and efficiency, a range of treatment methods are employed, such as multi-media filtration, ion exchange, reverse osmosis, electrodeionization and membrane technologies. Ecolutia uses Mettler-Toledo Thornton conductivity / resistivity, ph and ORP instrumentation for real-time measurement and control of the processes. Accurate measurement is required to provide information on the system performance which could otherwise lead to out of specification water quality and damage to filter media and membrane systems. The M300 transmitter and sensor ranges meet and exceed the requirements on projects where the mobile water treatment systems are operated. From the ease of use of the transmitters to the advanced range of robust sensors, Thornton instrumentation provides highly accurate performance. Chief Operating Officer for Ecolutia Services, Colin Wright commented Our experience with the Thornton equipment has proven successful and we are now pressing ahead to standardize and further incorporate them across our plants and systems. As the mobile water treatment systems are configured to suit the unique requirements of each specific customer, the instrumentation must also be flexible to allow for varied duties. The Thornton M300 series of process analytical instruments provides this flexibility with single-channel, multi-channel and multi-parameter models that can measure conductivity / resistivity, ph /ORP, dissolved oxygen, dissolved ozone and flow rate. Included with each M300 transmitter is a Transmitter Configuration Tool (TCT). This PC-based program allows the user to configure the M300, download, upload, save or print unique configurations specific to customer applications via the transmitter s USB port. c

6 The phenomenon known as single-phase FAC occurs in water-touched lines operating at moderate temperatures (typically near 150 C / 300 F) with high flow velocities, turbulence, and in a reducing environment. These conditions exist in feedwater piping, economizers, attemperator (desuperheater) lines, and other locations, where the water has been treated with an oxygen scavenger / metal passivator such as hydrazine. For this reason, many plants with all-ferrous feedwater components have eliminated reducing agent feed to allow operation under carefully-controlled oxidizing conditions which are much less corrosive and ensure a safer environment. Brad Buecker, process specialist at Kiewit Power Engineers, and a well-respected author and power plant chemistry expert, explains how he retrofitted a Mettler- Toledo Thornton 770MAX system to monitor the conversion of a unit in a mid-western US power plant from reducing to oxidizing chemistry: The all-ferrous condensate / feedwater system of a pulverized-coal boiler was on an all-volatile treatment reducing [AVT(R)] condensate / feedwater program. We decided to switch to all-volatile treatment oxidizing [AVT(O)] to minimize the potential for single-phase FAC in the feedwater piping and economizer. At the same time, we had been in touch with Mettler-Toledo Thornton about a multichannel, multi-parameter instrument to monitor conductivity and dissolved oxygen on the economizer inlet sample. We included ORP as an additional monitoring parameter. Where possible, conversions like this have given good results, although understanding of FAC and the techniques to minimize it continue to evolve. In plants with copper alloy-tubed feedwater heaters, an oxidizing environment is not acceptable since it would result in rapid copper corrosion and thus efficient deaeration and reducing agent feed are still required. These processes achieve the very low oxygen concentration (usually < 5 ppb) and reducing conditions that minimize copper corrosion by maintaining a consistent protective layer of cuprous oxide (Cu 2 O) on the tubes. It is precisely this environment that favors flow-accelerated corrosion of ferrous piping. Chrome-alloy steels placed in zones of high turbulence can reduce vulnerability to FAC, and primary examples are the pipe elbows in low-pressure economizers The combination of dissolved oxygen and ORP monitoring was excellent for evaluating process conditions. The instrument readings clearly showed that the conversion from [AVT(R)] to [AVT(O)] established the desired process chemistry. Subsequent lab analyses indicated very low iron corrosion rates in the feedwater system.

7 and evaporators of heat recovery steam generators (HRSG). However, in many cases it is not easy to identify all turbulent areas or what alloys are present in an existing plant. A chemistry approach, including accurate monitoring, is the only reasonable method to minimize FAC. Dissolved oxygen (DO) measurement has long been used to confirm the proper operation of de-aerators and control of reducing agent feed. It is now known that even in oxidizing environments singlephase FAC may occur at locations where flow causes a mechanical depletion of oxygen. Thus, low-level DO measurement is not an exceptionally good measure of FAC-inducing conditions that might exist within the system. Analyzers are also available to measure reducing agent concentration. However, they have historically been maintenanceintensive and do not accurately reveal the true feedwater environment. Conditions depend not only on reducing agent concentration but also upon metallurgy, ph, and the concentrations of dissolved oxygen, metal ions, and other impurities in the feedwater. Studies have shown ORP (oxidationreduction or redox potential) measurement to be quite valuable for monitoring reducing chemistry conditions in boiler feedwater. ORP is measured with an inert platinum electrode and a reference electrode identical to those used for ph. The platinum picks up a millivolt signal, which is related to the ratio of oxidizing and reducing species in contact with it. Under reducing conditions, the ORP goes negative and values between 200 to 350 mv (Ag /AgCl reference electrode) are common. Because every plant is different, it is important to determine an ORP range that achieves minimal iron and copper corrosion, and from that to set the reducing agent feed rate. Mettler-Toledo Thornton provides ORP measuring capability along with other common cycle chemistry parameters, including conductivity, ph and dissolved oxygen. A choice of several multipara meter transmitter platforms enables matching application requirements for 1, 2 or 4 channels of measurement with any combination of the above parameters. Readers can learn more about these instruments and the chemistry which they monitor at power conferences and exhibits such as Electric Utility Chemistry Workshops held annually in Champaign, Illinois, Southwest Chemistry Workshops held in the western US, EPRI Fossil Cycle Chemistry Conferences held in North America, and VGB and PowerPlant Chemistry conferences held in Europe. Find out more at: c

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