Level and Flow Wellhead Instrumentation Enhances Safety and Performance

Reliable wellhead instrumentation for level and flow control is critical to efficient processing and safety shutdown systems required of demanding production applications. The following steps in the wellhead production stream offer opportunities to realize better performance from your wellhead equipment, using level and flow measurement.

Wellhead Oil Field SeparatorWELLSTREAM SEPARATORS
Separators are large drums designed to separate wellstreams into their individual components. They are commonly designed to separate two-phase (gas/liquid) or three-phase (gas/crude/water) wellstreams. Separators are also classified according to horizontal or vertical configuration, operating pressure, turbulent or laminar flow, and test or production separation.

Interface level measurement will actuate a valve to adjust vessel level in the oil separation process. An emulsion layer along the oil/water interface can contaminate the oil with water or the water with oil. Foaming along the gas/liquid interface, if entrained, can cause liquid carryover or gas blow-by.

Level Technologies:
Continuous Level and Interface Level – Provides effective level measurement of gas/liquid interface that is insensitive to foam, to prevent liquid carryover or gas blow-by. Recommended: Eclipse® Model 706 guided wave radar transmitter
Visual Indication – Delivers technology redundancy and diversity, especially in remote, power-challenged sites where non-powered visual indication is preferred. Recommended: Orion Instruments® AtlasTM or Aurora® magnetic level indicator, or Jupiter® magnetostrictive transmitter
Flow Indication – Detects water level to activate shut-off. Recommended: Thermatel® Model TD2 flow/level/interface switch

Crude oil and water are stored at the wellhead. Unlike midstream tank farms at terminals and refineries, field storage consists of smaller vessels associated with oil and water processing. Diesel generator fuel, potable water and fire water are also stored.

Wellhead instrumentation that monitors level can provide overflow control and alarm systems or shut down pumps when level falls below the specified low level. Interface controls will sense the beginning of an oil/water interface during tank dewatering and control the water draw-off.

For Oil Tanks:
Continuous Level and Interface Level – Provides effective level measurement of gas/liquid interface that is insensitive to foam, to prevent liquid carryover or gas blow-by. Recommended: ECLIPSE Model 706 guided wave radar transmitter
Point Level – Effective “high alarm” device for overfill prevention. Recommended: Echotel® Model 961 ultrasonic level switch
Visual Indication – Delivers technology redundancy and diversity, especially in remote, power-challenged sites where non-powered visual indication is preferred. Recommended: ORION INSTRUMENTS ATLAS or AURORA magnetic level indicator, or JUPITER magnetostrictive transmitter

For Water Tanks:
Continuous Level – Effective level measurement across a wide range of process conditions. Recommended: Model R82 non-contact radar
Point Level – Effective “high alarm” device for overfill prevention. Recommended: ECHOTEL Model 961 ultrasonic level switch
Visual Indication – Delivers technology redundancy and diversity, especially in remote, power-challenged sites where non-powered visual indication is preferred. Recommended: ORION INSTRUMENTS ATLAS or AURORA magnetic level indicator, or JUPITER magnetostrictive transmitter

Wellhead Vapor Recovery UnitVAPOR RECOVERY UNIT
If allowed to escape into the atmosphere, hydrocarbon vapors diminish income through loss of hydrocarbon volume and create fire hazards and pollution problems. A vapor recovery unit (VRU) collects vapors from storage and loading facilities, reliquifies the vapors and returns the liquid hydrocarbons back to storage. Methods to recover vapors include absorption, condensation, adsorption and simple cooling.

A VRU is a simple, economical process unit that provides EPA compliance and improves operating economies by capturing up to 95% of fugitive emissions.

Continuous Flow Indication – Provides precise monitoring of hydrocarbon vapors and flared gases. Recommended: THERMATEL TA2 thermal dispersion mass flow meter

For more information about level and flow control applications in wellhead systems, click the link below.

Wellhead Instrumentation

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Look for Advanced Performance and Safety Benefits When Choosing an Ultrasonic Level Switch

Contact ultrasonic level switch technology was first applied to process control in the 1960s – and continues to provide accurate and reliable liquid level measurement in virtually every process industry today.

How an Ultrasonic Level Sensor Works

An ultrasonic level switch utilizes either continuous-wave or pulsed-signal technology.

Continuous-wave switches use two piezoelectric crystals positioned opposite each other across the transducer gap. The transmit crystal generates an acoustical signal that the receive crystal converts into an electrical signal. When liquid is present in the transducer gap, the amplifier becomes an oscillator causing a relay circuit in the electronics to indicate a wet gap condition. When liquid vacates the gap, the amplifier returns to an idle state.

Pulsed-signal ultrasonic level sensors feature a digital electronic amplifier that produces a powerful pulse of ultrasonic energy five to ten times stronger than most continuous wave units do. This pulsed-signal technology provides more accurate measurement in conditions of aeration, suspended solids, turbulence and highly viscous liquids.

The transmit crystal of pulse signal units generates pulses of high-frequency ultrasonic energy only milliseconds in duration. In between each pulse, the receive crystal “listens” for the transmission. If liquid is present in the gap, the receive crystal detects the pulse and reports a wet gap condition to the electronics. When the gap is filled with air, the receive crystal cannot detect the pulse, and reports a dry gap condition.

Expect Advanced Performance and Enhanced Safety From an Ultrasonic Level Sensor

Ultrasonic contact technology provides liquid level measurement in virtually every process industry, including chemical, petrochemical, power, water and wastewater, pulp and paper, food, and pharmaceutical industries. Ultrasonic level switch devices are typically used in a wide array of industrial applications that can help prevent equipment damage, including pump control, pump protection and seal pot level control. Additionally, ultrasonic contact technology offers important tank overfill protection safety features, including high level alarms, that can help your process plant, pipeline terminal or tank farm comply with API RP 2350 4th edition updates.

Specific design features of ultrasonic level switches are intended to enhance safety in process environments. In the information below, Echotel® contact ultrasonic level switches from Magnetrol® are used to highlight available safety features.ultrasonic_level_switch

  • Low cost single- and dual-point sensing is accurate and reliable in a wide variety of liquids.
  • Dual-point option is ideal for two-alarm safety protocol configuration.
  • Advanced self-test technology provides unsurpassed testing of electronics, transducer, piezoelectric crystals and electromagnetic noise, which makes this technology suitable for use in Safety Integrity Level (SIL) 2 loops.
  • Best-in-class safe failure fraction of greater than 91%.
  • Adjustable time delay for turbulent aerated liquids that prevents false level alarms due to waves or splashing.
  • Integral or remote mount electronics enable easy installation and simple configuration.
  • Remote mount capability keeps workers off top of tank for switch modification.
  • Pulsed signal technology works well in challenging process conditions such as aeration, suspended solids and high viscosities.
  • Extensive FM, CSA and ATEX explosion proof and intrinsically safe approvals.
  • The ability to transmit a stable signal despite liquid property changes in specific gravity, conductivity, pH and dielectric or temperature shifts.
  • Electronic switches contain no moving parts, which prevents degradation and high maintenance costs.

Additionally, ultrasonic level switches compare very favorably to tuning fork technology, which can have a negative impact on performance and profitability due to the time and labor required to calibrate tuning fork level switches. For more information about how ultrasonic level switches compare to tuning forks, view the MAGNETROL video on the subject.


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Magnetrol® Announces The “Just Can’t Stop A MAGNETROL” Contest

Magnetrol® International announces the “Just Can’t Stop a MAGNETROL” contest to honor the hardest-working, longest-lasting level switches still in operation. Ever since 640x980_JustCantStop_adMAGNETROL invented and introduced the first mechanical buoyancy switches to process industries over 80 years ago, customers have counted on their exceptional reliability and performance in level control applications – even after decades of service.

MAGNETROL switch owners can visit JustCantStop.Magnetrol.com between May 1, 2015 and October 31, 2015 and submit the device’s age, its application and a photo to be eligible to win one of three prizes:

  • 1st Place: $500 Amazon.com gift card, plus a new MAGENTROL mechanical buoyancy switch
  • 2nd Place: $300 Amazon.com gift card
  • 3rd Place: $100 Amazon.com gift card

First and second place prizes will be awarded based on the age of the unit and a description of the application in which the unit works. Third place prize will be awarded based on a random drawing of all qualified entries.

To enter the contest and for complete contest information, visit JustCantStop.Magnetrol.com.

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Guided Wave Radar Provides Accurate, Cost-Effective Level Measurement for Single Use Systems

A variety of technology solutions can measure level, volume and mass in single use systems utilizing disposable bioprocess bags. These include load cells, floor scales, pressure transmitters and guided wave radar.

In single use systems in bioprocessing, each technology poses its own set of benefits and limitations. For example, load cells, which determine weight, provide accurate, repeatable measurement but at a very high cost.

On the other hand, guided wave radar (GWR) level measurement is a far more cost effective control solution. However, potential difficulties arise when GWR is used in an environment using single use bioprocess bags. The nature of disposable, single use bags (in that they flex, fold and/or inconsistently form to the wall of a tote or bin) can negatively impact the repeatability of GWR level measurement.

Technical Article Demonstrates GWR Repeatability Optimization in Single Use Systems

Guided Wave Radar Operating Principle

Guided Wave Radar Operating Principle

A recently published article in Pharmaceutical Engineering, authored by David Ladoski, principal engineer at Amgen, and Dan Klees, hygienic business manager at Magnetrol®, investigates the use of GWR technology in a wide range of single use system environments. “Investigation of New Level Technologies in Single Use, Disposable Systems” compares variables including stainless steel bins, plastic/polymer and steel totes; solid rod and flexible cable probes; and inside wall and outside probe placement.

The article demonstrates that GWR technology, which typically costs one-third of the price of a load cell system, can deliver repeatability rates as low as 0.25% of total process liquid volume.

Additionally, the article discusses other benefits of GWR technology in single use systems, including the ability to perform periodic calibration verification on a bench dry calibration stand. For more information, we invite you to read the Pharmaceutical Engineering article, or contact Dan Klees at MAGNETROL.

Single Use Systems Article

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Eclipse® Model 706 Guided Wave Radar Transmitter Now With Modbus Protocol

Magnetrol® International has announced the release of the Eclipse® Model 706 guided wave radar (GWR) transmitter configured with Modbus protocol. The Modbus communications protocol is widely used in the unconventional oil and gas industry, where the ECLIPSE offers advanced liquid and interface level control to ensure accuracy, efficiency, reliability and ease of use for production applications.Modbus706

ECLIPSE Model 706 loop-powered, 24 VDC transmitters are designed with guided wave radar technology, which represents best-in-class liquid level instrumentation. The 706 offers high-performance solutions ideal for wellhead equipment including separators and oil tanks.

  • Fastest start-up and stabilization times reduce energy consumption.
  • Accurate top level and interface measurement delivers precise tank capacity control to reduce production costs.
  • Powerful diagnostics and data storage enable efficient remote monitoring.
  • Complete probe line ensures reliable performance in every application, regardless of media.
  • Compatible with industry standard RTUs.

For more information about ECLIPSE Model 706 GWR transmitters, visit eclipse.magnetrol.com or contact info@magnetrol.com.

Eclipse Microsite

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Level Solutions for Nuclear Power Plant Efficiency

As nuclear power plants continue to supply needed energy in many countries, ensuring power plant efficiency is crucial. Nuclear power plants must be able to handle the demands of energy consumption with minimum waste and maximum safety. Level instrumentation and pump protection can help maintain nuclear power plant efficiency during the storage, heating and cooling processes. In this blog post, the second of a two-part series on level solutions for the nuclear power industry, we will discuss level control applications for feedwater heaters and storage, diesel fuel storage tanks, lubrication oil storage, liquid waste storage, and cooling tower intake and basin levels. If you missed the first post, be sure to check it out, from April 7.

Feedwater Heaters and Storage

nuclear_power_plant_efficiency_1Application: Low and High Pressure Feedwater Heaters use extraction steam from the turbine to pre-heat feedwater destined for steam generation. The primary water sources for the heaters are the Condensers and Condensate Storage Tank. The Emergency Service Water System or the Ultimate Heat Sink (usually a river or lake) provides back-up feedwater to the SGs in the event of an interruption in the primary feedwater system.
Challenges: Redundant control loops manage feedwater heater level to prevent liquid from rising into the extraction steam; keep tubes in the condensing zone immersed; keep the drain cooler flooded, and optimize heater performance. The primary and back-up feedwater sources are typically equipped with level switches for valve actuation and alarms.
Level Instrumentation:
-Series 3 Float-Actuated External Cage Level Switch or B40 Float-Actuated Level Switch for point level
-E3 Modulevel® Displacer Transmitter or Eclipse® Model 706 Radar Transmitter for continuous level
-Atlas™ or Aurora® Magnetic Level Indicators for visual indication

Diesel Fuel Storage Tanks

Application: Diesel-powered engine-generator sets provide emergency power to operate critical nuclear plant systems in the event of a loss of station service power. The main nuclear_power_plant_efficiency_2diesel fuel storage tank provides a fuel capacity for one to seven days of full-load generator operation. The main storage tank is connected to an indoor day tank holding less than 1,000 gallons.
Challenges: Main storage tanks typically require a fuel level indicator with a remote indication transmitter. Sensors actuating electrical pumps connected to the main tank continuously monitor day tank fuel level. Day tank high-level alarms can lock out supply pumps until a system reset. Low levels and critical low-levels actuate alarms and the system will display the low-level conditions.
Level Instrumentation:
-Models A10 or B10 Displacer-Actuated Switches or Echotel® Model 961 Ultrasonic Switch for point level
-ECLIPSE Model 706 Guided Wave Radar, Pulsar® Model RX5 Radar Transmitter, or Jupiter® Magnetostrictive Level Transmitter for continuous level
-ATLAS or AURORA Magnetic Level Indicators for visual indication

Lubrication Oil Storage

Application: Nuclear plants operate many machines that require lubrication. Lubricants nuclear_power_plant_efficiency_3prevent damage caused by excessive friction and prolong equipment life. Oil is stored in stainless steel and carbon steel tanks. A generator gearbox lube oil system may have a reservoir with a capacity of 3,000 gallons and a turbine oil system may have a capacity of 150 gallons.
Challenges: Level monitoring of oil reservoirs will ensure the proper functioning of pumps, gearboxes, drives, compressors, materials handling equipment, generators and turbines. Temperature shifts in oil reservoirs affect media density that excludes some technologies, such as dP devices. Because ISO cleanliness levels increase oil change frequency, controls should be easy to remove.
Level Instrumentation: 
-ECHOTEL Model 961 Ultrasonic Switch or Tuffy® II Float- Actuated Switch for point level
-ECLIPSE Model 706 Guided Wave Radar or PULSAR Model RX5 Radar Transmitter for continuous level
-ATLAS or AURORA Magnetic Level Indicators for visual indication

Liquid Waste Storage

Application: Waste liquids from sumps, radioactive leakage collectors, the Reactor Cooling System (RCS), and allied systems are collected, stored and processed. Inactive wastes are discharged or reused; active wastes are collected for processing. Radioactive liquids can provide make-up to the RCS, the ECCS, and the spent fuel storage pool.nuclear_power_plant_efficiency_4
Challenges: Waste liquids are collected and stored in large single- and double-walled tanks designed to suit radioactivity levels. Tanks are monitored for activity levels and their contents are processed, released or reused. Tank level instruments, frequently of redundant design, indicate inventory levels and protect against overfilling or underfilling that cavitates pumps. Prevention of tank overfilling.
Level Instrumentation:
-Models A10 or B10 Displacer-Actuated Switches for point level
-ATLAS or AURORA Magnetic Level Indicators for visual indication

Cooling Tower Intake and Basin Levels

nuclear_power_plant_efficiency_5Application: The hyperbolic cooling tower releasing clouds of water vapor is the iconic image of nuclear power. Warm water from the condenser is pumped to the natural draft cooling tower, distributed to remove waste heat to the ambient atmosphere through evaporation, and collected in a basin prior to being recycled back to the condenser.
Challenges: The cooling tower’s intake structure, typically a vertical wet pit, requires level sensing and pump control. Water basin level controls maintain level through the addition of make-up water and are frequently configured with high and low level alarms.
Level Instrumentation:
-ECHOTEL Model 961 Ultrasonic Switch for point level
-ECLIPSE Model 706 Guided Wave Radar, or PULSAR Model RX5 Radar Transmitter or ECHOTEL Model 355 Non-Contact Ultrasonic Transmitter for continuous level
-Thermatel® Model TD1/TD2 Switch for flow and pump protection

Nuclear Power Level Control


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Nuclear Power Plant Instrumentation for Level Control

According to the World Nuclear Association, there are over 435 commercial nuclear power reactors operable in 31 countries, providing over 11% of the world’s electricity as continuous, reliable base-load power, without carbon dioxide emissions. As the world continues to leverage nuclear power as a clean energy source, the demand for improved performance from existing and next-generation reactors increases. Nuclear power plant instrumentation, including level measurement and control devices, must meet the challenge to enhance the efficiency and safety of these facilities.

This blog article addresses level instrumentation applications in reactor containment structures. The pressurized water reactor (PWR) and the boiling water reactor (BWR) represent the world’s two most common forms of nuclear power generation. The level applications discussed below utilize instruments for process control. Typically, a separate level control using a diverse technology serves as an alarm for spill detection.

Emergency Coolant Tanks

nuclear_power_plant_instrumentation_1Application: The Emergency Core Cooling System (ECCS) supplies cooling water to the reactor during an interruption of the reactor’s normal cooling system. Upwards of 250,000 gallons of emergency make-up water is drawn from Refueling Water Storage Tanks (RWST) during the injection phase and from a containment sump during the second recirculation phase.
Challenges: Level control of Refueling Water Storage Tanks is essential for emergency cooling operations. Low levels in these tanks can trigger actuation of pumps which bring additional coolant from accumulators, deaerators, de-mineralized water tanks, and treated condensate tanks. The ECCS can be tripped by an indication of coolant pressure loss or by low level of reactor coolant.
Level Instrumentation: 
-Models A10 or B10 Displacer-Actuated Switches for point level
-Eclipse® Model 706 Guided Wave Radar Transmitter or Pulsar® Model R95 Pulse Burst Radar Transmitter for continuous level
-Atlas™ or Aurora® Magnetic Level Indicators for visual indication

SCRAM Discharge Volume Tanks

Application: A SCRAM is a rapid shutdown of a nuclear reactor whereby control rods are inserted between the fuel rods in the reactor core to discontinue the fission reaction. The nuclear_power_plant_instrumentation_2SCRAM is actuated manually by an operator or automatically when parameters are exceeded. When control rods are inserted, radioactive coolant is displaced by the rods and routed to a storage tank. This “hot” coolant is later processed and routed back to the recirculation system.
Challenges: Level instrumentation in the Discharge Volume Tank is an important control in the Reactor Protection System (RPS). The level controls must be approved for radioactive service in a steam environment. Conventional float switches are frequently specified as they meet these requirements with high reliability.
Level Instrumentation: 
-Model B40 Float-Actuated External Cage Switch for point level
-E3 Modulevel® Displacer Transmitter (remote version only) for continuous level
-ATLAS Magnetic Level Indicator for visual indication

Steam Generator

nuclear_power_plant_instrumentation_3Application: Primary coolant circulating in a PWR is heated under extremely high pressures to prevent boiling. The heated coolant enters two or more boilers called Steam Generators (SG) and boils the secondary loop coolant in a heat transfer process accomplished without mixing the fluids together. The coolant turns to steam which drives the turbine-generator.
Challenges: 30% of emergency PWR shutdowns are attributable to SG level control problems. Controls balance feedwater to steam flow under all operating conditions. High-high levels can trip the turbine. Abnormally low levels can actuate emergency feedwater or a reactor shutdown. Measurement accuracy is challenged by thermal reverse effects known as “shrink and swell” and by static pressure effects.
Level Instrumentation:
-Series 3 Float-Actuated External Cage Level Switch; or B40 Float-Actuated Level Switch for point level
-E3 MODULEVEL Displacer Transmitter or ECLIPSE Model 706 Radar Transmitter for continuous level
-ATLAS or AURORA Magnetic Level Indicators for visual indication

Containment and Drainage Sumps

Application: A plant has many low-lying drainage reservoirs known as sumps. Small sumps include pump enclosures and tank rupture basins that contain leakage. The nuclear_power_plant_instrumentation_4reactor’s large, containment sump is an essential reservoir of the ECCS whose function is to continuously circulate coolant through the reactor once all coolant storage tanks are depleted.
Challenges: Small sumps are monitored for leak detection with simple, float-operated level switches designed for bracket mounting in floor level sumps or troughs. These switches detect leaks or spills from pumps, valves, vessels, and pipelines. Levels of the large containment sump, or ECCS sump, are monitored during the recirculation phase of residual heat removal when the reactor’s primary coolant system is down.
Level Instrumentation:
-Models A10 or B10 Displacer-Actuated Switches for point level
-ECLIPSE Model 706 Guided Wave Radar with Single Rod Probe (remote version only) for continuous level
-ATLAS Magnetic Level Indicator for visual indication

Spent Fuel Pool

nuclear_power_plant_instrumentation_5Application: One-third of the total fuel load of a reactor is removed from the core every 12 to 18 months and replaced with fresh fuel. Spent fuel rods generate intense heat and high radiation and are stored underwater in pools with depths of 20 to 40 feet. The water cools the fuel and provides radiation shielding. Spent fuel is later sent for reprocessing or dry cask storage.
Challenges: Without cooling, the spent fuel pool water will heat up and boil. Exposed fuel assemblies will overheat, melt or combust. Pool level is tightly controlled and water is continuously cooled by recirculation to heat exchangers and then back to the pool to resume cooling. High and low level alarms as well as redundant continuous level indication are typically required.
Level Instrumentation:
-Models A10 or B10 Displacer-Actuated Switches for point level
-PULSAR Model RX5 Radar Transmitter for continuous level

Be sure to check out the Magnetrol blog next week for the second part of our discussion on level control applications for nuclear power plants.

Nuclear Power Level Control

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Flow Solutions and Technologies for Chemical Processing

The chemical processing industry relies heavily on flow processes, such as mass air and compressed air flow, process and waste gas flow, tank blanketing, and pump protection. Reliable flow measurement and instrumentation is key to the efficiency and safety of these processes. Flow technology can ensure that chemical processing runs smoothly and without leaks or spills. In this article, the last in Magnetrol’s series on the chemical industry, we will discuss flow technology applications and solutions for chemical processing. If you missed the rest of the series of level and flow applications for the chemical industry, be sure to catch up on the other posts, from February 10, February 17, March 3, March 10, and March 17. 

Mass Air & Compressed Air Flow

chemical_processing_1Application: The flow of air is monitored in nearly all industrial settings, including applications for processing, air/gas mixing, cooling, blowing & drying, combustion, aeration, ventilation, filtration, and ingredients mixing. Compressed air (CA) is essential for pneumatic tools, materials handling, oxidation, fractionalization, cryogenics, dehydration, filtration and aeration.

Challenges: Significant air-flow variables include pipe diameters, wide flow ranges, varying velocities and low flow sensitivity. Flow meters help ensure efficient operation at rated SCFM output and detect air leaks. A flow meter with a totalizer provides an accurate measurement of CA consumption.

Flow Technologies:
Thermatel® Model TD1/TD2 Thermal Dispersion Flow Switch for flow alarm
– THERMATEL Model TA2 Thermal Dispersion Mass Flow Meter for continuous flow

Process & Waste Gas Flow

Application: Common process gases used in chemical, pharmaceutical, plastics, semi-conductor, food, beverage, and petrochemical processing include compressed air, natural chemical_processing_2gas, nitrogen, argon, hydrogen, oxygen, and carbon dioxide. Industrial waste exhaust gases are present in a wide variety of compositions from benign to toxic. Measurement of the flow of these later gases is often required for reporting environmental emissions.

Challenges: Continuous mass flow measurement of compressed gases help improve plant efficiency. Often these applications require high turndown capabilities and low flow measurement with varying gas pressures and temperatures. Thermal mass flow measurement ideally handles these applications providing high accuracy and high turndown with reliable, dependable operation.

Flow Technologies:
– THERMATEL Model TD1/TD2 Thermal Dispersion Flow Switch for flow alarm
– THERMATEL Model TA2 Thermal Dispersion Mass Flow Meter for continuous flow

Tank Blanketing

chemical_processing_3Application: Nitrogen—the most widely used commercial gas—is the ideal tank blanketing gas when injected into the vapor space of a storage tank. It prevents ignition of flammable liquids, inhibits vapor loss, and protects chemicals, pharmaceuticals and foods from oxygen and moisture degradation. Nitrogen is also used as a purging agent and in cryogenic applications.

Challenges: Mass flow measurement will monitor the nitrogen blanketing gas. A mass flow meter can track usage as a cost control measure by determining when and where gas is used. Flow monitoring of feed lines can prevent unsafe conditions that may arise when gas supply is insufficient.

Flow Technologies:
– THERMATEL Model TD1/TD2 Thermal Dispersion Flow Switch for flow alarm
– THERMATEL Model TA2 Thermal Dispersion Mass Flow Meter for continuous flow

Pump Protection

Application: Pumps are used throughout chemical operations for moving process fluids.chemical_processing_4 Whether caused by a closed valve, a plugged line downstream or by pump cavitation, pumps operating in a reduced or no-flow condition can overheat and rupture the pump’s seal and cause a dangerous deviation in process pressure and temperature.

Challenges: A flow switch along a pump’s discharge piping will actuate an alarm and shut down the pump when liquid flow drops below the minimum flow rate. Solid state switches provide the highest level of protection in these instances by offering low flow sensitivity, wide temperature operation and high turndown.

Flow Technologies:
– THERMATEL Model TD1/TD2 Thermal Dispersion Flow Switch for flow alarm
– THERMATEL Model TD1/TD2 Thermal Dispersion Flow Switch for pump protection


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Upgrading Your Feedwater Heater Level Controls: Is It Worth It?

by Don Hite, Power Industry Business Development Manager

A global outlook for the installed base of coal-fired and, to some degree, nuclear power generation can leave decision makers staring into a crystal ball when deciding whether or not to pursue investments in technologies that improve feedwater heater level control and ultimately plant efficiency (heat rate), while significantly reducing maintenance cost.   In North America, for example, coal is the environmental equivalent of a four-letter word. On the other hand, China, India, Japan and Southeast Asia, as well as other regions, see their vast coal reserves as a valuable asset upon which their long-term energy security is hinged. Nuclear power shares a similar dilemma, with public concerns about safety and the upfront engineering cost associated with change as factors affecting industry development.

I am not going pretend my crystal ball is any better than the next guy’s, but I am willing to step out on the limb a bit to share some insight from my work with various clients in the power industries. Hopefully, the information will be helpful to those who are entertaining the “is it worth it?” aspect of feedwater heater level controls.

Countries that view coal-fired and nuclear generation as part of their long-term strategic plan can realize gains in efficiency and maintenance sufficient to recover the cost of retrofitting their level controls at roughly around two to two-and-a-half years. Of course, there are a number of factors that come into play including, but not limited to, the performance of existing controls relative to feedwater optimization. Nonetheless, there is certainly value when you factor efficiency, environmental and maintenance benefits into the equation, which ultimately drop to the bottom line. In regions where the future of coal-fired generation is up in the air, i.e., retiring due to age, environmental constraints/impact, overall inefficiencies and so forth, I see plants pushing the timeframe out to five or more years, where the first two years are spent recovering the investment through operational, performance and maintenance gains and profits are realized for the duration of the plant’s lifecycle. Note the nuclear power industry may experience a slightly longer cost recovery period due to additional front-end engineering requirements.

The scope of the balance of this post is not to highlight the application and cost benefits of the Magnetrol® Eclipse® guided wave radar (GWR) as compared to traditional level technologies employed on feedwater heaters prior to…. let’s say the 1999-2004 timeframe.  I’m assuming you have already opted for the technology, so I focus the discussion on the path to retrofitting an existing installation to a state-of-the-art configuration as well as some cost considerations.   If you’re not at this point yet, you can download our literature at eclipse.magnetrol.com, which details the upside of GWR, or feel free drop me an email to discuss specifics at dhite@magnetrol.com.   Additionally, if you would like more information on how the technology can improve performance – thus, heat rate – please download the whitepaper “Heat Rate and Feedwater Heater Level Control” from Magnetrol’s website via the link below. Be advised this is one you won’t want to put down.

Feedwater Heater Level Control

For those of you who are continuing on with the conversation, there are three consistent feedwater heater retrofit scenarios I encounter in the field relative to coal-fired and nuclear generation.

The first is upgrading from torque tube (displacer) technology to GWR, which can be as simple as removing the “guts” of the torque tube (displacer) and replacing with the GWR utilizing the existing chamber. Or, it can be more complex if the original installation is a top-in/bottom-out type process connection with a control scheme comprising an imbedded PID (set point) controller for local, pneumatic control to maintain “normal water level” in the feedwater heater. Yes, pneumatic controls are still out there. I used the latter scenario in my example (Retrofit Option 1) since it is the most expensive route and requires additional hardware to install the GWR and maintain the existing control scheme. It is easy enough to eliminate portions that may not apply to a particular installation or a less complicated scenario, e.g., we can delete the PID controller and I/P converter if the torque tube transmitter and pneumatic controls have been upgraded to transmit a 4-20mA signal to the DCS.

The second most common retrofit involves upgrading a differential pressure installation where no existing, external chamber is available to accommodate the GWR, but we can take advantage of available process connections. This scenario falls more in line with the example in Retrofit Option 2 relative to cost.

Last, but not least, is retrofitting an RF capacitance or magnetic level indicator coupled with a magnetostrictive-type level transmitter. This scenario is pretty straightforward since, in most cases, the existing external chamber can be used, making it a simple matter of removing/replacing the current technology with GWR. Adding an external chamber (Retrofit Option 2) covers situations where this is not the case or where an Aurora® configuration (Orion® Instruments magnetic level indicator with integral GWR) is preferred.

HP Feedwater Heater

Triple redundancy on HP feedwater heater: Two standalone ECLIPSE guided wave radar units and an AURORA configuration (ORION Instruments magnetic level indicator with integral GWR)

Here we pursue a “kill two birds with a single stone” approach in that this option offers a solution for retrofitting the torque tube level transmitter/controller to GWR technology, as well as upgrading the sight (glass) gage to reduce overall maintenance costs*, while at the same time providing a higher margin of personnel safety. As mentioned, this is a worst case scenario in that the process connections for the torque tube (top-in/bottom-out) are problematic when retrofitting with a top mounted technology and the pneumatic control scheme at this site was to remain intact.

Taking advantage of the side/side process mounting configuration of the existing sight (glass) gage location on each feedwater heater (Figure 1) is the most straightforward method of retrofitting the torque tube level controllers with an AURORA configuration (magnetic level indicator with integral GWR).

Magnetic Level Indicator

Although this method adds some cost to the instrument itself and may require the introduction of isolation valves, it eliminates plumbing modifications to accommodate a side/bottom process connection configuration (Retrofit Option 2) for the GWR, along with the bonus of alleviating ongoing sight (glass) gage issues. By the way, I mention the isolation valves only because they are integral to the sight (glass) gage in some instances. If the valves are separate, we can use what is in place.

This is a practical approach since sight (glass) gages are not mandated in the ASME boiler code relative to feedwater heaters; hence, they are rarely encountered in new feedwater heater installations. The AURORA (MLI with integral GWR) offers the best of both worlds: highly accurate level indication along with the host of other GWR benefits, coupled with an easily readable and redundant visual indication. The cost of replacing/repairing the sight (glass) gage in the above image would more than offset the additional cost of the instrumentation. Installation would simply be a matter of removing the sight (glass) gage and socket welding the necessary isolation valves (as required) and the AURORA configuration in its place.

To maintain a control scheme consistent with an existing pneumatic design, the new system will include a PID (set point) Controller and I/P converter as an interim set point control solution. The PID controller will accept the 4-20mA feedwater level signal from the ECLIPSE GWR, and calculate the control output where it will be converted to the corresponding pressure (3-15 psi or 3-27 psi) by the I/P converter for appropriate valve operation to maintain “normal water level” in the feedwater heater. The PID controller and I/P converter can be easily removed and the 4-20mA output signal routed directly to the I/O cabinet for the DCS in the future or if the existing control scheme can accommodate the analogy output of the GWR. (Figure 2)

PID Controller Schematic

*The primary failures of sight/tubular (glass) gages are due to leakage from a steam cut or failed seal or integral valve and etched glass. The repair process goes something like this: Remove the unit; sandblast; shave surface; install repair kit; reassemble and torque bolts; reinstall on vessel; bring vessel up to temperature and back down; verify torque values. The following details the cost associated with repair of these devices.

Retrofit 1 Budget

Budgetary Considerations (Retrofit Option 1):

  • AURORA (MLI with Integral GWR)
    • ECLIPSE Model 706 Guided Wave Radar with Coaxial Steam Probe
  • PID Process Controller
    • Outputs:  4-20mA
  • I/P transducer, non-explosion proof
    • Input – 4-20mA
    • Output: 3 – 15 psig/3 – 27 psig
  • Other Items
    • Enclosure for PID Controller and I/P Converter
    • Isolation Valves (if existing integral to sight (glass) gage)
    • Labor

Utilizing the existing torque tube, RF capacitance or magnetic level indicator chamber is one of the easiest and most cost effective methods of retrofitting a feedwater heater to incorporate more advanced level control technologies. The process is simply a matter of verifying the existing chamber can accommodate GWR, ensuring the GWR comes with the proper mating flange and subsequent removal and replacement.

As alluded to earlier in the conversation, there are installations, where the existing chamber will not suffice for whatever reason – usually, the top-in/bottom-out process connection configuration (Figure 3). In this situation the cleanest route to implementing the GWR solution is to replace the existing chamber with one incorporating a side/bottom or side/side process mounting configuration. This also applies to differential pressure retrofits where no external chamber exists; however, the original level transmitter process connections will be used to mount the external chamber and the GWR.


Level control scheme is consistent with the options described in Figure 2.

Budgetary Considerations (Option 2):

  • ECLIPSE Guided Wave Radar with external chamber
    • Model 706 Guided Wave Radar with Coaxial Steam Probe
    • Chamber: (side/bottom or side/side process connections (as required)
  • PID Process Controller (as required)
    • Outputs:  4-20mA
  • I/P transducer, non-explosion proof (as required)
    • Input – 4-20mA
    • Output: 3 – 15 psig/3 – 27 psig
  • Other Items
    • Enclosure for PID Controller and I/P Converter (as required)
    • Labor


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Level Control Applications for the Chemical Processing Industry

The chemical processing industry is dependent on proper level control to ensure safety and efficiency. Storage and processing technologies such as waste sumps, neutralization, liquids storage and liquefied gas storage can benefit from level instrumentation and improve their performance. In this article, part of Magnetrol’s series on the chemical processing industry, we will explore the impact that level control instrumentation can have on chemical manufacturing and storage. If you missed the previous posts in the series, be sure to catch up on them, from February 10, February 17, March 3, and March 10. 

Waste Sump

chemical_processing_industryApplication: Industrial chemical plants generate large volumes of liquid wastes and runoffs that are collected in large open-atmosphere sumps—concrete lift stations, in-ground pits or reservoirs. When the collected liquid reaches a pre-determined level it is discharged for transport to waste storage, treatment, or disposal facilities.

Challenges: Level controls typically actuate a pump to automatically control sump level between two set points. The control can be configured to activate an alarm and a pump shutdown to avoid overfill or pump cavitation in the event of too high or too low levels. Sump level controls must often be robust enough to contend with corrosive media, high solids content and very punishing weather.

Level Technologies:
– Model A10 Displacer-Actuated Level Switch for point level
– Echotel® Model 338 Ultrasonic Transmitter for continuous level


Application: To protect neighboring water systems, industrial wastewater must be neutralized so that it is neither acidic nor chemical_processing_industry_2alkaline prior to its discharge. The neutralization process takes place in a tank where aqueous solutions of an acid and a base are added to wastewater. Sulfuric acid, sodium hydroxide and calcium carbonate are most commonly used.

Challenges: Level is measured in the neutralization and chemical regeneration tanks, which typically involve agitation and aggressive chemicals. Ideally, the tank level monitoring system should be easily removable for frequent cleaning. Contact level sensors should be single rod types to avoid media buildup.

Level Technologies:
– ECHOTEL Model 961 Ultrasonic Level Switch for point level
– Pulsar® Model RX5 Pulse Burst Radar Transmitter or ECHOTEL Model 338 Ultrasonic Transmitter for continuous level
– Orion Instruments® Atlas™ or Aurora® Magnetic Level Indicators for visual indication

Liquids Storage

chemical_processing_industry_3Application: Liquids stored at chemical plants include water (potable, demineralized, fire, cooling), ingredients and finished product storage. Hazardous chemicals include inorganic acids, buffers, ammonia, chlorine, and solvents. Tanks range in size from small plastic totes to large steel tanks. The chemical stored and the tank type largely determine the level control used.

Challenges: Level instruments indicate inventory levels and protect against tank overfills and underfills that cavitate pumps. As some chemicals are corrosive enough to destroy contact sensors, or can crystallize and coat sensors to render them ineffective, non-contact level monitoring, resistant materials, by-pass chambers and redundant controls are sometimes used.

Level Technologies:
– Model A10 Displacer-Actuated Level Switch for point level
– PULSAR Model RX5 Pulse Burst Radar Transmitter or ECHOTEL Model 338 Transmitter for continuous level
– ORION Instruments ATLAS or AURORA Magnetic Level Indicators for visual indication

Liquified Gas Storage

Application: Gases are frequently converted to a liquid to facilitate convenient storage. chemical_processing_industry_4Many liquefy by cooling at normal atmospheric pressure while others require pressurization as well. Industrial gases commonly stored in this fashion include liquid oxygen, liquid nitrogen, liquefied chlorine, LPG and LNG. Gases are re-vaporized through an application of heat.

Challenges: Above or below ground insulated storage tanks are built to specifically hold liquefied gases and minimize the amount of evaporation. Liquefied gas tank level monitoring typically contends with pressurization, extremely low temperatures and low dielectric media. Contact and non-contact measurement sensors may require a standpipe.

Level Technologies:
– Series 3 Float-Actuated External Cage Switch or Tuffy® II Float- Actuated Switch for point level
– Eclipse® Model 706 Guided Wave Radar or PULSAR Model RX5 Pulse Burst Radar Transmitter for continuous level
– ORION Instruments ATLAS or AURORA Magnetic Level Indicators for visual indication


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