Driving Down Fuel Costs With Feedwater Heater Level Control

For most power plants, 70 to 80% of their production costs are fuel expenses. Hence, any improvement in fuel efficiency can have a significant impact on a plant’s profitability. By improving final feedwater heater temperature through better feedwater heater level control, plants can reduce heat rate and realize significant cost savings. For instance, in a 500-megawatt power plant, improving heat rate by 1% could generate $500,000 in annual savings.

Heat rate is a measure of how efficiently a plant uses heat energy. The higher the heat rate, the less efficient the plant. Heat rate has a major impact on a company’s bottom line and its ability to compete in unregulated markets. The benefits of an improved heat rate go well beyond consumption and cost. A plant can see a reduction in emissions by simply reducing the amount of fuel required to generate a given amount of energy. In many cases this can be accomplished in a cost-effective manner by improving feedwater heater level control. Reducing heat rate also increases boiler longevity by eliminating overfiring. And there is significant public relations value when a plant shows itself to be taking all possible steps to minimize its impact on the environment.

Level Control Throughout the Power Cycle
Maintaining accurate, reliable level control throughout the power cycle is critical. The condenser is the beginning of the feedwater heater process, where condensed steam from feedwater heater drains and HP, IP, and LP turbines is routed through successive feedwater heaters. At the same time, extraction steam from turbines reaches the appropriate feedwater heaters and the transfer of energy takes place. Reliable, accurate level control is critical to achieving the final temperatures that this cycle requires.

feedwater heater level controlFeedwater Heater Operation
Feedwater heaters use the heat of condensation to preheat water to the correct temperature for the boiler. During this process, shell and tube heat exchangers allow feedwater to pass through the tube side and extract water from the turbine to the shell side. When controlled properly, feedwater heaters can decrease fuel costs by using extraction steam to preheat water rather than costly hot fuel. Achieving optimum water level in the feedwater heater reduces heat rate and lowers fuel costs. Making an investment in level control can help you achieve optimum heat.

Instrumentation for Feedwater Heater Level Control
The Eclipse® Model 706, a guided wave radar transmitter produced by Magnetrol®, is a smart choice for monitoring feedwater heater level control. The ECLIPSE 706 guided wave radar (GWR) transmitter can help plant operators optimize the condensing zone, deliver accurate level control, maximize energy transfer, and minimize undue wear and tear.

While older level technologies, such as differential pressure, magnetostrictive, RF capacitance, and torque tubes are often used to measure feedwater heater level, these instruments can cause issues for power plant operators. Older technologies such as these are vulnerable to process conditions, induced instrument errors, shifts in specific gravity and mechanical or electronic drift.

GWR is the truly reliable measurement solution for feedwater heater level control, because it is unaffected by process conditions, requires no calibration or gravity corrections, and has superior signal-to-noise ratio. Using a guided wave radar transmitter like the ECLIPSE Model 706 can help power plants achieve a reduced heat rate and lower fuel costs.

More Information
To learn more about feedwater heater level control, and to download a kit about managing your heat rate, visit heatrate.magnetrol.com.


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Level Measurement Solutions for Chemical Distillation Towers

Separation and purification is a crucial part of all industrial operations that deal with chemicals. Selecting a separation technology from among 20 leading varieties depends upon a chemical’s nature, the number of phases, and the capacity, speed and efficiency required. Distillation—separating substances based on differences in volatilities—is the most widely used separation and purification method. Today, approximately 40,000 distillation towers are operating in U.S. chemical plants.

Magnetrol® has produced a brochure detailing different applications throughout the distillation towerschemical industry and exploring measurement challenges and solutions for each one. This blog post is part of an occasional series exploring each application in detail.

Level Measurement Challenges and Considerations
Distillation is an energy-intensive process—in a typical chemical plant, it accounts for about 40% of the total energy consumption. Reliable level measurement is needed in order to maintain energy efficiency throughout the distillation process and lower the fuel costs needed to distill. In addition, level measurement at the bottom of a distillation tower controls the “bottoms” product rate. Poor high level control could allow liquid to back up over the stripping trays causing damage and reduced yields. Too low of a level may cause pump cavitation. In related extraction and distillation towers, interface level control provides optimal separation from associated substances.

Level Instrumentation Solutions
MAGNETROL offers a range of level instrumentation solutions for chemical extraction and distillation towers:

  • For point level measurement
    Series 3 float-actuated external cage level switch
  • For continuous level measurement
    Eclipse® Model 706 guided wave radar transmitter or E3 Modulevel® displacer-actuated transmitter
  • For visual indication
    Atlas™ or Aurora® Magnetic Level Indicators can be supplied with switches or transmitters

More Information
For more information on level measurement solutions for distillation towers and other chemical industry applications, download the Chemical Industry brochure.


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Answers to Key Measurement Questions About Thermal Mass Flow Meters

The Magnetrol® flow portal, flow.magnetrol.com, provides information about thermal mass flow meters and how they can improve the efficiency and safety of many processes. Periodically, MAGNETROL product manager Tom Kemme answers questions about flow meters in the portal’s Ask the Expert column. This week’s blog shares some recent Q&As.

Question: What is the difference between the flow units Nm3/h, Sm3/h, and actual m3/h?

thermal mass flow meters

Magnetrol® expert Tom Kemme answers your questions.

Answer: Actual m3/h is a flow rate at operating temperature and pressure. Normal or standard m3/h (Nm3/h = Sm3/h) is a flow rate at standard temperature and pressure (STP). I tend to reference the natural gas industry, where it is not possible to compare flow rates at every operating condition, so it is preferable to reference all flow rates back to a set of base conditions, such as 60°F and 1 atm. STP is not universal so it may be unique based on the region or industry.

Most flow meters output a flow rate at operating conditions and need to correct this measurement. This may be accomplished with a multivariable transmitter or external to the device. A few examples that do not need to correct the measurement are thermal mass flow meters, such as the ones produced by MAGNETROL, and Coriolis flow meters.

Question: Do you have any certified failure rate data on your units to perform an SIL verification?

Answer: A Failure Modes, Effects, and Diagnostics Analysis (FMEDA) is completed during development to determine failure rates and Safe Failure Fraction (SFF). The SFF is utilized to determine Safety Integrity Level (SIL), which is often the published value.

Question: What should my meter be reading with no air flow in the pipe?

Answer: At zero flow and a dry pipe, a thermal mass flow meter should measure zero. Different thermal meters may have varying stability at no flow due to differences in operation.

There are two different types of operation: constant temperature (CT) and constant power (CP). CT devices start with a low power and this power increases with the flow rate to maintain the constant temperature difference (ΔT) between the RTDs. CP devices start with a high ΔT between RTDs at low flow and the ΔT decreases as the flow rate increases. CP may lack stability at zero flow due to possible convection currents associated with the high ΔT. CT will hold zero better, particularly devices that add less heat. For example, the maximum surface temperature of a TA2 probe is 4 C above process temperature. This is extremely low heat, eliminating convection currents due to the sensor. Convection currents could also occur through the pipe due to temperature variations.

It is also possible for a thermal meter to measure above zero during a no flow condition when there is pressure buildup in the line (typically a valve closed downstream). There may be low flow cutoff settings that can be changed to ignore nuisance measurements.

More Information

For more information about thermal mass flow meters, or to ask a question of your own, visit flow.magnetrol.com.


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Happy New Year From Magnetrol!

happy new year

All of us at Magnetrol® wish you a happy and successful 2017! Thanks for being part of making our 2016 great.

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Happy Holidays From Magnetrol

happy holidays

Magnetrol® would like to wish you all a safe and happy holiday season! May you find peace and joy during this special time of year.

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Level and Flow Measurement for Water and Wastewater Treatment Plants

In a world more focused than ever on safe, sustainable stewardship of our water resources, it is critical to continue to improve the ways in which we measure and treat potable water and wastewater. Increased public awareness drives the need for safe, accurate and reliable level and flow instrumentation, in the harshest environments, under the most extreme conditions. At the same time, the regulatory climate requires plants to implement next-generation process improvement – moving from energy efficiency to energy independence and realizing cost-savings in doing so. Innovations in level and flow control can help water and wastewater treatment plants manage energy usage and monitor applications more effectively.

wastewater treatment plants

A Polaris® electromagnetic flow meter

Magnetrol® offers a wide range of instrumentation for water and wastewater applications, designed to monitor level, flow and volume at every step of the treatment process. Below are a few of the instruments that can help you better manage your treatment plant.

Pulse Burst Radar

The MAGNETROL Model R82 pulse burst radar transmitter provides radar-reliable process measurement in challenging, vapor-saturated environments. It is inexpensive enough to be used in place of ultrasonic transmitters, making it a cost-effective choice.

In a water treatment plant, the R82 can provide continuous level measurement for:

  • lift station and coagulant feed tanks
  • settling tanks during clarification
  • polymer, filter, and lime slurry tanks during filtration
  • open atmospheric water reservoirs where control technology must withstand weather conditions

The R82 is also a reliable option for wastewater treatment plants, where it can:

  • control level at lift station pump, open channel flow and screening system
  • monitor feed tanks containing chemical coagulants, oxidants and phosphorus precipitations
  • measure splitter box and clarifier levels
  • control corrosion inhibitors
  • manage PH adjustment, mixed liquor and secondary clarifier levels
  • provide activated sludge and digester level control

Thermal Dispersion Mass Flow Meters

Flow measurement plays a vital role in efficiently managing water quality processes and regulatory reporting protocol. MAGNETROL produces the Thermatel® Model TA2 thermal dispersion mass flow meter to monitor these applications. The THERMATEL TA2 offers outstanding accuracy and reliability, as well as the ability to maintain a strong signal at low flow rates and pressure over a wide operating flow range.

The THERMATEL TA2 is ideal for wastewater operations due to its low flow sensitivity, wide temperature operation and high turndown capabilities. It can manage efficient blower airflow to optimize breakdown of waste and reduce blower costs. The THERMATEL TA2 also offers exceptional safety and accuracy for digester gas flow measurement.

Electromagnetic Flow Meters

The Polaris® electromagnetic flow meter, produced by MAGNETROL, offers flow monitoring that can help maintain efficient water and wastewater operations. POLARIS flow meters can measure forward and reverse flow rates through the capability of empty pipe detection. Closed pipe flow control is a widespread application for POLARIS throughout water treatment plants. In wastewater treatment facilities, POLARIS flow meters provide efficient water and sludge flow control. The flow meters have current, pulse and alarm outputs that are configurable through the display or a device type manager, making POLARIS a flexible choice for flow control.

More Information

These are just a few of the options MAGNETROL offers for water and wastewater process instrumentation. For more information on level, flow and volume control for water and wastewater treatment plants, please visit water.magnetrol.com.

wastewater treatment plants

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Increasing Energy Efficiency by Tracking Natural Gas With Flowmeters

With today’s increased emphasis on strategic energy management, many throughout the chemical process industries and elsewhere are attempting to obtain better information on the natural gas consumption in their facilities. While custody-transfer flowmeters are typically in place at the property line (to track total gas consumption throughout the facility), the flow to individual combustion sources, such as heaters, furnaces, boilers and so on, generally remains unknown. When armed with better information on actual natural gas utilization, users can optimize the combustion performance by operating combustion processes at peak efficiency.

Similarly, when users measure actual natural gas flow, they are able to determine which of their units is the most efficient. The operating efficiency of furnaces or dryers will vary. Knowing which process unit is the most efficient can result in significant cost savings. For instance, if more than one furnace, dryer or other type of gas-consuming unit is available, the user will be able to choose the combustion unit that provides the highest efficiency.

A Magnetrol® TA2 thermal mass flow meter

A Magnetrol® TA2 thermal mass flow meter

The first step to better energy management and improved energy efficiency is to obtain good measurements of the flow rates of each individual combustion source. In addition to providing tools for improving energy management, the measurement of the natural gas utilized by individual combustion sources may also permit users to meet the regulatory requirements for determining emissions by reporting actual (rather than estimated) natural gas usage for each individual combustion source within the facility.

Concerns When Installing Flowmeters

There are many different ways to measure the flow of gases. The difficulty in obtaining good gas flow measurements is the simple fact that gases are compressible, and thus the volume of the gas is dependent upon the pressure and temperature at the point of measurement.

Chemical engineers will recall the basic concepts of the Ideal Gas Law, whereby gas volume is proportional to the temperature and inversely proportional to the pressure. This complicates gas flow measurement because, with the exception of thermal mass and Coriolis flowmeters, many gas flow measurement technologies measure the flow at the actual operating pressure and temperature.

Thermal Mass Flowmeters

Thermal mass flowmeters provide an inferred measurement of the mass flow of the gases passing through them. Specifically, thermal mass flowmeters measure heat transfer that is caused as the molecules (hence, the mass) of gas flow past a heated surface. The relationship between heat transfer and mass flow is obtained during the calibration of the instrument.

In addition to providing a mass flow measurement without the need for additional devices to correct for pressure and temperature (as is required with many other flow measurement devices), thermal flowmeters also provide the following advantages:

  • Lower flow sensitivity. A thermal mass flowmeter will easily measure flow rates that are much lower than those that can be measured using orifice plates or vortex flowmeters. This permits a thermal flowmeter to be retrofitted into existing natural gas pipes using a simple NPT (national pipe thread) thread or flange connection on the pipe. This simplifies installation compared to other flowmeters, which may require a reduction in the pipe size in order to obtain the desired rangeability.
  • Higher turndown capabilities. Some combustion systems may have a high natural gas firing rate during initial warm-up operation and then, once the desired temperature has been obtained, the flowrate of the gas is typically reduced to maintain the desired operating temperature. A thermal mass flowmeter can easily handle this range, which may be difficult to obtain with other technologies.
  • Simplified installation. An insertion device permits simplicity of installing the flowmeter using NPT connection, flange, compression fitting or even a complete retractable probe assembly. Using a “hot tap” permits the user to install the flowmeter without having to shut down the operation. The insertion design also permits the use of the same instrument in different pipe sizes. Some use the insertion probe as a semi-portable instrument and reconfigure the transmitter for the different pipe sizes.
  • Lower pressure drop. There is virtually no pressure drop when using a thermal mass flowmeter. This is advantageous in low-pressure applications where other technologies would consume operating pressure.

More Information

Magnetrol® produces a thermal mass flowmeter, the Thermatel® TA2, which can be used for natural gas applications. To learn more about the THERMATEL TA2 and other advantages of flowmeters, please visit flow.magnetrol.com.


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How to Minimize Your Insurance Risk With Overfill Protection

The oil and gas industry is no stranger to incidents that have resulted in stricter regulations and guidelines for operating safely and responsibly. Since the Buncefield overfill accident in 2005, overfill protection has had a spotlight on it from global regulatory organizations to make sure this type of accident does not happen again.

Both American Petroleum Institute (API) and Health and Safety Executive (HSE) have instituted new guidelines to help ensure proper overfill prevention through management systems and safety-integrated systems of level measurement in storage tanks. All of these guidelines are targeted at reducing the risk of a Buncefield-type incident occurring at any storage terminal on a global scale. There are benefits to risk reduction that go beyond just incident prevention, including a reduction in liability insurance for storage terminals. Storage terminal operators and insurance providers have different perspectives on liability insurance and how they evaluate and minimize the risk.

overfill protection

Protect your plant against accidents and disasters.

Assessing Insurance Risk

Insurance agencies look at how much a storage terminal location has minimized the risk of events deemed catastrophic to the environment and employees. Overfill protection is one aspect of the risk reduction that is reviewed for liability insurance. The insurance agency will review the local jurisdictional requirements and industry guidelines when determining the insurance rates. During this review, the insurance agent is looking for evidence that the safety measures are properly maintained, as well as that each safety measure is functioning properly. It is important for the devices that are used as safety guards to have an ability to be easily tested and maintained.

Many insurance agencies will make recommendations based on failure modes they have experienced to ensure safety. These recommendations include processes to maintain operation, but also features of the level transmitters or switches themselves. Level transmitters for tank level should have internal diagnostics that are able to identify issues when they exist. Level alarms (or switches) should be able to be proof tested either electronically or manually to ensure proper functioning. By choosing the appropriate level transmitters and switches with these capabilities, the overall risk of an incident is reduced and the insurance premium is much lower.

Assessing Operation Risk

From the insurance customer’s perspective, the narrative changes. Plant operations staff are concerned with the ability to operate profitably based on expenses and costs. Storage terminals have to deal with both fixed and variable costs that must be managed in order to operate profitably. As it was noted above, this can be managed by making sure that risk has been reduced across the terminal. Operators can receive the recommendations of the insurance agencies and work to make the best selections of their level instrumentation based on those recommendations. Typically, they can expect to be audited by the insurance entity (external or internal) to review their level instrumentation annually, so it is important to stay compliant. Operators take on a large amount of risk by not following the recommendations of the insurance agencies and could face fines for not complying with industry standards if an incident were to occur. They can evaluate the level instrumentation on the market, but it can help to get guidance from suppliers that parallels the insurance agency recommendations.

Level Transmitter and Switch Providers

By selecting the appropriate level instrumentation, a storage terminal site can demonstrate that it has taken measures to reduce the risk of overfill or other hazardous situations. As level instrumentation technology has advanced, continuous level transmitters have become more prevalent in storage terminal level control. There are many transmitters on the market that have self-diagnostics that are constantly running to assess the health of the device. Based on the storage terminal’s assessment of critical tank levels, the transmitter can identify when these levels are reached, allowing ample time to remove product from the tank as part of the overfill protection system.

Beyond previously using point level controls, continuous level measurement devices can provide real time level readings to control rooms while tanks are being filled/emptied. This helps the operator reduce the risk of having a dangerous event by knowing the tank level in real time. A further risk reduction step is to utilize additional point level controls as the failsafe alarms. The continuous level device can have the output set to alarm certain functions, but if those were to fail, then the additional alarms at high and low level can provide emergency shut down or emergency pumping of product to avoid an overfill. These devices can be as simple as a mechanical level switch with manual proof test capability, or they can be as sophisticated as an electronic point level switch using ultrasonic technology with built in self-test diagnostics. Either of these are industry acceptable and provide an added layer of protection to meet industry standards and reduce overfill risk.

More Information

Magnetrol® has produced an overfill protection kit with resources to help you comply with regulations like API RP 2350 and minimize your insurance risk. Visit api2350.magnetrol.com to download the kit today.


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There’s No Debate: It Pays to Take Control of Your Heat Rate

In this election year, two hot-button issues have been energy efficiency and cost control. Politicians on a local and national level have argued over the challenges these topics present in today’s business climate.

However, one point that’s not debatable is the potential savings a power plant can realize by improving efficiency. Taking control of your heat rate can help you use energy more efficiently, minimize fuel costs and improve your bottom line.

Here’s fact that underscores the point very clearly: Improving heat rate by merely 1% can generate $500,000 in annual savings for a 500-megawatt power plant. (A 1% improvement in heat rate is worth $500,000 in annual fuel cost savings based on: Fuel cost of $1.25/million Btu, Capacity factor of 85% and Boiler efficiency of 88%.)

Two Causes of Heat Rate Inefficiency and Fuel Cost Acceleration

Fuel expenditures are often the largest production expense for power plants. For most power plant operators, these expenditures account for 70% to 80% of production costs.

heat rate

Eclipse® Model 706 Guided Wave Radar

It’s also important to note that as a plant ages it becomes even less efficient. Most power plants have a life expectancy of 30 to 40 years, and many plants are at or reaching their operational longevity.

In addition, older plants often use outdated level technologies that cannot achieve a performance level sufficient to manage controllable losses due to instrument-induced errors.

Here are two causes of heat rate inefficiency that can be overcome.

  1. Mechanical or electronic drift due to aging instrumentation, moving parts or intrinsic design. Torque tube/displacer technology requires calibration between shutdowns to achieve reasonable accuracy and prevent nuisance deviation alarms between multiple level transmitters. In addition, this technology may take too long to respond to rapid level changes due to dampening effects that are fundamental to its principle of operation.
  1. Measurement technology that is vulnerable to process conditions.
    Shifts in specific gravity and the dielectric constant of media related to variations in process pressure and temperature affect the accuracy of differential pressure, magnetostrictive, RF capacitance and torque tube/displacer technologies. As a result, these technologies cannot provide accurate level from startup to operational temperatures without applying external correction factors – or can only deliver the specified accuracy at operational temperatures. To compound the issue, calibrations performed on these technologies during a shutdown often require adjustment when the process reaches operating temperature to maintain acceptable control and prevent unnecessary deviation alarms.

The bottom line is that aging level instrumentation combined with instrument-induced errors negatively impacts heat rate and fuel costs.

Proven Technologies for Heat Rate Reduction Efforts

Power plant operators that want to reduce their heat rate should consider highly accurate level control solutions needed to satisfy the most complex applications.

Magnetrol® provides a full array of innovative and reliable level measurement solutions, including the industry-leading guided wave radar:

Eclipse® 706 Guided Wave Radar Transmitter

Why Choose It: Leading edge level transmitter designed to provide measurement performance well beyond that of many of the more traditional technologies.

Key Benefits:

  • Complete proactive diagnostics with automated waveform capture
  • Available with DTMs and allows for HART or Foundation FieldbusTM installations
  • Accurately measures from the bottom to the top of the probe for small ranges without a dead zone or transition zone
  • Superior signal-to-noise ratio

MAGNETROL provides effective solutions to help make all of your level applications – including feedwater heaters, condenser hotwells, deaerators, cooling towers, air heaters and compressed/instrument air – as efficient as possible.

More Information

For more information about managing heat rate and controllable losses, visit heatrate.magnetrol.com.

heat rate

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E3 Modulevel® Displacer Level Transmitter Outperforms Torque Tubes

For continuous liquid level measurement, many operators turn to a displacer level transmitter to monitor their applications. The two main technologies that are used as displacer level transmitters are torque tubes and range spring/LVDT (Linear Variable Differential Transformer) technologies. There are substantial advantages to range spring/LVDT technologies over torque tubes. Magnetrol® produces a range spring displacer level transmitter, the E3 Modulevel®, which is suitable for a wide range of applications, from light hydrocarbons to viscous slurries. Below are some of the many reasons why the E3 MODULEVEL is the superior choice for liquid level measurement:

displacer level transmitter

E3 Modulevel® displacer level transmitter

Advantages of the E3 Modulevel®

  • Increased sensor motion. MAGNETROL displacer transmitter output is produced by 1¼ inches of sensor movement, almost twice as much motion compared to the ⅝ of an inch of sensor movement that produces torque tube output. This increased motion leads to a stable output without a need for artificial damping or flow restriction.
  • Greater output stability. Torque tubes are generally oversensitive, producing an unstable output. The range spring technology in a MAGNETROL displacer level transmitter dampens the effect of vibration and turbulence. Not only does this result in an output with four times the stability, it also provides reliable measurement for tougher applications.
  • Decreased wear and tear. Torque tubes are constructed with a knife-edge bearing that leads to a point of stress, where wear and tear can significantly damage the function of the instrument. Vertical range spring movement is friction-free, eliminating the potential for wear and tear.
  • A smaller footprint. E3 MODULEVEL transmitters weigh 30% less than torque tubes, and are more compact, for a smaller footprint in the application and easier maintenance.
  • Enhanced remote mount capabilities. The E3 MODULEVEL can be mounted up to 400 feet away from the application and still perform at top levels. In contrast to that, torque tubes must be mounted no more than 30 feet away from the application in order to function.
  • Flexibility. Unlike a torque tube, the head of the E3 MODULEVEL can be removed without depressurizing the process or chamber if maintenance is required. In addition, the head can also be rotated 360° to accommodate any installation. Torque tubes must have their installation angle specified during manufacture and cannot be changed in the application.

More Information
For more information on the E3 MODULEVEL and how it can help improve the efficiency of your application, visit e3modulevel.magnetrol.com.

displacer level transmitter

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