Level and Flow Solutions for Ammonia Refrigeration Skids

Refrigeration is a key component of almost every industry. Aside from the obvious applications, like air conditioning and cold storage, refrigeration is used throughout many industries to facilitate processing. It’s employed for solvent recovery, liquefaction, gas separation, condensing, and heat exchange. In power generation, it cools inlet air for improved turbine performance. In oil refineries and chemical plants, refrigeration maintains low temperature processes, as in the alkylation of butane. Pharmaceutical refrigeration chills glycol in reactor vessels and immersion chillers, and removes water vapor and CO2 from preparations. With the majority of countries now agreeing to eliminate hydro-chlorofluorocarbon coolants by 2020, absorption refrigeration (also known as ammonia refrigeration) has become a leading industrial refrigerant.

Many owner/operators, OEMs and plant engineers fabricate their refrigeration units as modular skid systems. These systems are growing in popularity due to their efficiency and minimal site disruption. This post discusses level and flow solutions for ammonia refrigeration skids and is part of an occasional Magnetrol® blog series on modular skid systems.

Ammonia Refrigeration Skids

In an ammonia refrigeration skid, the refrigeration process cycles ammonia (refrigerant) and water (absorbent) through a compressor, condenser, high and low pressure receiver tanks, a throttling device, and evaporators, from where the process recycles.


Level and Flow Applications

  1. Condenser
    The condenser transfers heat from the refrigerant to a coolant medium—usually ambient air. Water-cooled condensers continuously circulate water to absorb refrigerant heat. Level controls monitoring the water basin include high and low level alarms.
    Continuous Level: Eclipse® Model 706 Guided Wave Radar Transmitter or E3 Modulevel® Displacer Transmitter
    Point Level: Tuffy® II Float Level Switch or Echotel® Model 910 Ultrasonic Switch
  1. High Pressure Liquid Receiver
    A high pressure receiver tank provides a buffer for liquid refrigerant as demand varies, and uses a recirculator to pump the refrigerant to multiple evaporator units. The tank is monitored for level.
    Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter
    Point Level: Model B35 External Cage Float Switch
  1. Low Pressure Liquid Receiver
    A low pressure receiver tank provides a buffer for liquid refrigerant as demand varies, and uses a recirculator to pump the refrigerant to multiple evaporator units. The tank is monitored for level.
    Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter
    Point Level: External Cage Displacer Switch or ECHOTEL Model 940/941 Ultrasonic Switch
  1. Evaporator
    Water level in the evaporator needs to be controlled close to the setpoint. Higher levels can put the refrigerant compressor in danger due to liquid carryover, while lower levels will result in smaller heat transfer rates.
    Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter or E3 MODULEVEL Displacer Transmitter
    Point Level: Model B35 External Cage Float Switch or ECHOTEL Model 940/941 Ultrasonic Switch

Pump Protection
Pumps operating on the skid are protected by flow switches that actuate an alarm in the event of no-flow conditions.
Flow Alarm: Thermatel® Model TD1/TD2 Thermal Dispersion Switch for low-flow cutoff


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Optimizing Plant Energy Management to Increase Efficiency

When it comes to plant energy management, the ability to better monitor combustion air, fuel gas flow and compressed air can help identify losses that over short periods of time can affect profitability. Regardless of the scale of an operation, any improvements in efficiency to purchased fuel and electricity consumption drop directly to a company’s bottom line. The ability to monitor the end-use location of fuel throughout a facility as well as the consumption specifics for individual applications — predominately the boiler — can offer insight to potential areas of improvement. The same is true of electricity consumption. In both instances, reductions can be realized by simply identifying where the energy is being lost.

The ideal instrumentation for monitoring energy usage is cost-effective and provides a strong return on investment. The goal is to realize the benefit in the shortest time frame possible at the most reasonable cost. Thermal dispersion mass flow meters are an optimal choice for both these considerations.

plant energy management

A Magnetrol® TA2 thermal mass flow meter in the field

Benefits of Thermal Mass Flow Meters for Energy Management

Thermal mass flow meters are primarily used in air and gas flow measurement applications. The meters consist of a transmitter and probe with temperature sensors (RTDs) located in the pins at the bottom of the probe. The reference sensor measures the process temperature and the other sensor is heated to a specific temperature above the reference. As the flow rate increases, heat gets taken away from the heated sensor. More power is then applied to the heated sensor to maintain the temperature difference. The relationship between power and mass flow rate is established during factory calibration.

There are many benefits to using thermal dispersion mass flow meters in plant energy management applications:

  • Repeatability of ±5% of reading
  • Direct mass flow measurement without the need for pressure or temperature compensation
  • Easy installation
  • No on-site or in-situ calibration
  • Strong signal, high turndown and good sensitivity with low flow rates
  • Accurate measurement under varying pressures

Considerations for Better Plant Energy Management

When looking for ways to improve plant efficiency, there are a few areas where better, more accurate measurement can make a difference. Combustion air flow measurement to a boiler is important to maintain a stoichiometric ratio with the amount of fuel being supplied. Too little air flow can result in incomplete combustion along with additional carbon monoxide or pollutants depending on the fuel being burned. On the other hand, too much air flow can cool the furnace and waste heat out of the stack. The repeatability of the air measurement is essential to obtaining the most efficient air-fuel ratio (AFR).

Measuring fuel gas flow (natural gas or propane) usage to individual combustion sources compared to the output (steam/hot water) can help optimize boiler efficiency and better manage energy consumption. Knowing individual boiler performance may also assist in operating those offering the best efficiency. Lowering fuel consumption is one of the easiest methods to reduce cost and improve profits.

Another key component of energy and facilities management is making compressed air systems more reliable and efficient. Valuable resources are wasted when a leak goes unnoticed or cannot be easily isolated.

By implementing more effective measurement solutions, plants can reduce the inefficiencies that lead to hidden maintenance costs and improve their steam generation. To learn more about level and flow measurement for all aspects of the steam generation cycle, visit steamgen.magnetrol.com.

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Level Solutions for Yeast Separator Efficiency

Yeast, the microorgan­ism responsible for fermenta­tion, also greatly influences a beer’s flavor and character. In the latter stages of beer production, brewers remove the spent yeast from fer­mented beer through the use of a yeast separator. The fermented beer is processed down­stream and the spent yeast is processed for resale.

In addition to their battle to gain the favor of consumers, attaining operational efficienciesyeast separator has always been essential for brewers. Beer and yeast separation and recovery is one aspect of the brewing process where using a yeast separator with a cyclone can realize greater efficiencies.

Separating Yeast From Beer

Separators have been essential equipment in beer brewing for decades. They ensure economical operation, a higher quality of beer, and efficient reclamation of beer and spent yeast. Over a period of time, however, a work­ing separator starts to lose its efficiency due to yeast packing, and the bowl of the separator must be dis­charged of packed yeast. The bowl discharge of the sepa­rator is called a “shoot.” The objective of controlling the shoots is to clean the separator bowl of caked yeast and also minimize the amount of beer that is lost when the separator bowl is open.

When the separator bowl shoots, it discharges the beer and yeast mixture into the top of the cyclone, tan­gentially to the sidewall. The yeast/beer slurry decelerates and col­lects in the bottom of the cyclone. The spent yeast is then pumped out of the bottom of the cyclone by means of a positive displacement or peristaltic pump and enters a yeast decanter or thermalizer. Any beer that is discharged with the shoot is lost.

The cyclone also acts as a surge vessel between the separa­tor bowl and the spent yeast storage, located below the pump. When the bowl shoots, additional beer will be dis­charged with the yeast into the cyclone.

Level Measurement for Yeast Separators

One Magnetrol® customer, a major U.S. brewer, had controlled the level in 64 cyclones throughout its breweries by using a competitor’s point level capacitance probe. The probe measured high level only and indicated when the cyclone was full of yeast/beer slurry. The brewer wanted to use a more precise measurement technique to capture more information about the cyclone.

MAGNETROL worked with one of the company’s brew­eries to prove that continuous level measurements could be made in a cyclone using guided wave radar (GWR) technology.

With the MAGNETROL Eclipse® GWR transmitter, the probe rod can be bent, enabling the brewer to measure down the sidewall, down the cone at the bottom of the cyclone, and into the discharge piping below the cyclone. By measuring level down to the outlet, the brewer can determine when there is slurry in the bottom of the cyclone and initiating pumping into the spent yeast cyclone. When the level is low, the pump will be stopped. This operation controls the discharge of the cyclone during separator shoots.

During normal separation of yeast (clarification of the beer), the separator bowl remains closed – not discharging slurry into the cyclone. However, the bowl of a separator is sealed by an elastomeric gasket. That gasket is prone to leakage, allowing good beer to be discharged at a low rate into the cyclone.

Using a guided wave radar transmitter, this brewer now monitors the cyclone level between shoots of the separator. If the separator bowl seal is leaking, the level in the cyclone will slowly increase. Therefore, by monitoring the level between shoots, the “health” of the separator bowl seal is monitored. If a leak is identified, the yeast separator is scheduled to have the bowl seal replaced.

Magnetrol now has 64 ECLIPSE trans­mitters installed to provide continuous cyclone measurement through­out the company’s breweries.

If this brewer can save one tenth of one percent of the beer by utilizing GWR, this translates into saving tens of thousands of gallons of beer per year! To learn more about guided wave radar and its other applications, visit radar.magnetrol.com.

guided wave radar

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Level and Flow Solutions for Pump Skids

Pump skids for fluid transfer are often found in field and factory processes. These skids move a broad range of fluids: from asphalt, cement slurries and drilling mud to potable water, hot condensate and every imaginable liquid chemical. Pump skids typically range from 10 HP electric-powered units to 1500 HP diesel skids with multiple pumps.

These pumps, especially condensate recovery pumps, can be configured as self-contained, modular skid systems. Modular skids are favored by many owner/operators, OEMs and plant engineers because of their flexibility, cost-effectiveness and reduced site disruption during fabrication. This post will discuss level and flow solutions for pump skids in the power industry used for condensate recovery and is part of an occasional Magnetrol® blog series on modular skid systems.

Condensate Recovery Pump Skid

Because condensate leaving a steam trap retains up to 25% of its original heat energy, recovery and utilization of condensate reduces feedwater make-up, fuel and water treatment costs. Pumping is necessary when the condensate return pressure is higher than the process/source condensate pressure.

A condensate recovery pump skid typically has one to four pumps, a condensate receiver tank (15 to 1,500 gallons; 57 to 5,678 liters), control panel, gate valves, drain valves, blowdown valves, condensate piping, and may include a heat exchanger, flash vessel or condensate cooler.


Level and Flow Applications for Condensate Recovery Pump Skids 

  1. Heat Exchanger or Steam Heater
    In steam heaters, steam is condensed while the process fluid is heated. One common control arrangement cascades the temperature controller to a level controller. The controller senses the rise in level due to an increase in process load and opens a fluid valve.
    Continuous Level: Eclipse® Model 706 Guided Wave Radar Transmitter or E3 Modulevel® Displacer Transmitter
    Point Level: Model B35 External Cage Float Switch
  1. Condensate Receiver Tank
    A receiver tank is placed below the heat exchanger to receive condensate that drains from the bottom. When the control senses the high level in the tank, it will actuate a valve to remove the accumulated condensate.
    Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter; E3 MODULEVEL Displacer Transmitter; Pulsar® Model RX5 Radar Transmitter; Model R82 Radar Transmitter or Echotel® Model 355 Non-Contact Ultrasonic Transmitter
    Point Level: Model B35 External Cage Float Switch
  1. Flash Vessel and Condensate Cooler
    Condensate and flash steam enter the flash vessel. The condensate falls to the base of the vessel where it is drained. Level measurement is necessary to control the flash tank level. In this stage of the process, the challenges are elevated temperatures and pressures.
    Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter
    Point Level: Model B35 External Cage Float Switch
  1. Pump Protection
    Pumps operating in a reduced or no-flow condition can overheat and rupture the pump’s seal. 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.
    Flow Alarm: Thermatel® Model TD1/TD2 Thermal Dispersion Switch for low-flow cutoff


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Guided Wave Radar Helps Drive Performance for Oil Well Cementing Trucks

oil well cementing

An Eclipse® guided wave radar transmitter in use in an oil well cementing truck

Mixing and pumping cement into a drilled borehole is one of the most critical steps in oil and gas well production. The injected slurry hardens to form a strong, protective sheath around the drilling string and isolates it from surrounding geologic features. Oil well cementing is typically among the first operations to prepare a well for production and one of the last operations to plug a well prior to its abandonment.

The cement sheath creates a smooth internal bore for operating well-drilling equipment. It fortifies drill pipe strength, protects the casing from shock loads during operation, and wards off contamination and corrosion. Through zonal isolation, cementing segregates the various zones that may have different pressures or fluids. By sealing off high-pressure zones from the surface, cementing curbs blowout potential.

Cementing also stabilizes surrounding geology and prevents unstable formations from caving-in and bogging down the drill string to bring production to a halt. Cement’s impermeable seal prevents water, soil, and sand from contaminating the well flow.

Level Control Considerations for Oil Well Cementing

Mixing and injecting the cement into a well is accomplished by truck-mounted, trailer-mounted and skid-mounted equipment configurations. The mobile cementing truck, with its integrated mixing, pumping, and control systems, is the preferred choice among oilfield professionals. Trucks feature bulk transport or batch mixing units and an accompanying high-pressure pump to force the slurry down the casing. The mixing system blends Portland cement, water, and various additives that affect the weight, density, behavior, and setting time of the slurry. Control systems typically include automatic density control and data recording systems with user-friendly interfaces, serial data output, and manual backup controls. An essential consideration for the performance of the control system is effective level control.

Accurate mixing and storage tank levels are key parameters. Measurement must be precise and responsive since sluggish level response can lead to delayed control reactions that damage cementing systems and shut down operations when tanks exceed high or low level limits. The level control’s ability to deliver consistently uniform, blended slurries that meet performance criteria is vital throughout the life of the equipment. In addition to accuracy, responsiveness, user-friendliness, and reliability, the mobile level controls must be extremely robust to tolerate the day-in, day-out concussions of oilfield travel.

A Measurement Success Story

A leading manufacturer of cementing equipment in China wanted the above attributes in level controls for the cementing trucks it manufactures. The measured medium is a complex mix: an agitated slurry with foam, solids, and changing density. Operation is under atmospheric pressure with a typical temperature of around +95oF (+35o C). Liquid additives mixed into the slurry reduce viscosity to about 60 centipoise (cP), which is similar in viscosity to corn oil.

Given the nature of this application, the petroleum machinery manufacturing company selected the Magnetrol® Eclipse® Guided Wave Radar (GWR) level transmitter with an overfill-capable probe installed in an external cage with a 31 inch (800 mm) center-to-center measurement range. The closed coaxial design tends to reject the false target that foam is known to produce, and the probe’s high accuracy ensures safe and efficient operation. The convenient user interface makes field adjustment and configuration quick and easy.

The ECLIPSE guided wave radar unit was tested against competitive GWR instrumentation. Two advantages gave ECLIPSE transmitters the edge. First, the response time was extremely quick – within one second – and thus showed operators real-time level. Competitors’ units required a full 10 seconds to respond. Second, the overfill safe probe delivered outstanding performance, giving accurate level readings to the top of the probe and close to the very top of the tank. By demonstrating best-in-class transmitter response time and full probe measurement range, over 100 ECLIPSE GWR transmitters were used for upgrades to the customer’s oil well cementing trucks.

More Information

For more information on guided wave radar and how it performs in a variety of applications, visit radar.magnetrol.com.

guided wave radar

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Magnetrol International NV Nominated for Entrepreneurship Award

As they have in previous years, the Belgian economic magazine “Trends” searched for “Gazelles”—fast growing companies that symbolize competitive entrepreneurship.

Magnetrol® International NV, located in Zele, Belgium, was among the nominees for this gazelle awardsaward. MAGNETROL was nominated in the “Large Companies” category. The category contains companies with sales of at least €10 million. These companies reinforce the competitive capacity of the area, thereby having a positive influence on business in general.

Based on data and information published in Trends Top 100,000, the editors of “Trends” examine which of the companies have grown the fastest in the period from 2010 – 2014, as far as turnover, personnel and cash flow are concerned.

Since 1971, MAGNETROL International NV has had a branch office in Zele (larger Ghent Area), Belgium. MAGNETROL grows each year and creates additional opportunities on the job market, two key factors that are taken into account when nominating companies for the Gazelles Award. Congratulations to MAGNETROL on this nomination.

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Thermal Mass Flow Meters Save Energy in Wastewater Treatment Plants

Thermal mass flow meters are one of many energy-saving technology solutions that can be used in a variety of applications, including the treatment of wastewater. Various types of processes are used by wastewater treatment plants to remove organic pollutants. Activated sludge systems are currently the most widely used biological treatment. In the activated sludge process, a portion of the activated sludge (frequently from the secondary clarifier) is returned to the aeration basin. Wastewater flows continuously into the aeration basin where air is injected into the wastewater to mix it with the activated sludge. This also provides the oxygen needed for the microorganisms to break down the organic pollutants.

Compressed air is normally used to provide air into the basins. Controlling the amount of air that is released is very important since it controls the growth and the health of the microorganisms. Flow meters are typically installed in the pipes to measure and control the amount of air to run the system properly.

The cost of energy to produce compressed air has increased tremendously due to the high cost of fuel. Regulating and controlling the air injection not only reduces the amount of energy consumed but also optimizes the operation of the plant. While there are many technologies to measure the flow rate of air, most of these methods measure the flow rate at the actual operating pressure and temperature, and require pressure and temperature correction to obtain the mass flow. Traditionally, the most common benefit of thermal dispersion mass flow measurement is the inherent ability to directly measure the mass flow without the need for pressure and temperature correction, as required with volumetric gas flow measurement. This not only provides a more useful flow measurement, but also makes thermal very cost-effective.

Thermal Dispersion Technology

Thermal dispersion technologies are based on the operational principle that states the rate of heat transfer by a flow stream is proportional to its mass flow. The flow measurement is accomplished by precisely measuring the cooling effect as the mass (molecular) flow passes the heated sensor. The sensor consists of two elements: the reference, which measures the temperature of the gas, and a second element, which is heated at a variable power to maintain the desired temperature difference between the two sensors. The illustration below shows the amount of power required to maintain a constant temperature difference between the two sensors. Under low mass flow conditions, there is minimal cooling and little power is required. As the mass flow increases, more power is required. The thermal mass flow meter provides excellent low flow sensitivity and high turndown capabilities.

thermal mass flow meters

Technology Benefits

Thermal mass flow meters offer many advantages over traditional technologies:

  1. Mass flow measurement based upon heat transfer. No correction of the gas flow rate for pressure or temperature is required.
  2. Excellent low flow sensitivity. Sensitive to velocities down to 10 standard feet per minute.
  3. Excellent turndown. Turndown of 100:1 or more depending upon the application requirements and calibration of the instrument.
  4. Low pressure drop. The insertion probe has little blockage of the pipe, creating very low pressure drops.
  5. Ease in installation. The insertion probe can easily be installed in a pipe or duct.
  6. Low installation cost. When considering options to measure mass flow, thermal dispersion has the lowest installed cost while providing excellent performance. No additional instrumentation is required to obtain a mass flow measurement.

Improved process optimization and reduced energy consumption are the main benefits of selecting the proper flow meter for your plant. There are multiple ways to measure air and gas flow rates; thermal mass flow meters should be considered as one of the proven and acceptable methods of measuring air and gas flows in the wastewater industry. For more information on flow instrumentation for this and other applications, visit flow.magnetrol.com.


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Level Technologies for Chemical Storage Tanks and Makeup Water Treatment

Makeup water treatment is a critical component of the steam generation cycle. It is the means to resupply the system with water suitable for boiler and other operations that, for whatever reason, was lost in the cycle. Unlike other aspects of the steam generation cycle, level control for the water treatment process is not necessarily about efficiency, but rather, accuracy, reliability and safety while providing proper inventory management to ensure chemical storage tanks and makeup water supply meet demand.

chemical storage tanks

High-visibility magnetic level indicator with a magnetostrictive transmitter supports the offloading of ammonia at a combined cycle power plant

The chemical component of the water treatment often presents difficulties for level technologies that may work perfectly on non-chemical applications related to the water treatment process or those with limited variations in the contents of the vessel’s vapor space. Although ammonia, acid, caustic and other chemical storage tanks are not difficult level applications by any stretch, small nuances in how the vessels are monitored relative to level technology can have a dramatic effect on the day-to-day practicality and reliability of the type of instrument(s) used. Additionally, there are safety considerations when replenishing chemicals, as well as short-and long-term maintenance costs, which can be addressed simultaneously with inventory monitoring by implementing a few simple, cost-effective modifications to the instrumentation package.

Considerations for Storage Tank Applications

Demineralization, water header and chemical storage tanks come in a variety of shapes and sizes, usually horizontal or vertical vessels six to ten feet in diameter/height, with the ammonia storage and demineralizer tanks being the largest. It is not uncommon to see some type of level transmitter (ultrasonic being the most prevalent) installed to provide level indication to the control room with a local display at the base of the tank, either in series with the 4–20 mA transmitter output or repeated from the control room. The signal to the control room tracks inventory, acts as a high alarm for overfill protection and establishes the resupply interval. The local display facilitates monitoring the offload of chemicals from the supplier’s truck.

Key Components to Chemical Storage Monitoring

The ideal technology for chemical storage monitoring would be able to address all of these components:

  • Inventory Management (for accuracy)
  • Resistance to chemical attack (for reliability & maintenance)
  • Unaffected by changes in the vapor space of the vessel (for reliability)
  • Performance verification (for maintenance)
  • Visibility during product transfer (for safety)

Chemical Storage and Water Treatment Level Technologies

Accuracy, reliability and visibility in dynamic vessel environments and operational scenarios are a level technology’s best attributes when addressing chemical storage applications. Any number of level technologies can be used in chemical storage tanks. Adhering to the principles of minimizing the number of variables (e.g., vulnerability to process dynamics, calibration, hardware complexity, etc.) that can affect a technology’s ability to perform as intended is a key step in reducing the total cost of ownership. Guided wave (contact) radar as well as its through-air (non-contact) radar counterpart excel in these areas. These two technologies are also very tolerant to a changing vapor space. Magnetic level indicators (MLI) operating in conjunction with Guided Wave Radar or coupled with a magnetostrictive level transmitter offer redundancy and technology diversity while enhancing visibility for improved safety during resupply operations. There is also the added benefit of redundancy when verifying the primary transmitter’s performance during periodic inspections on scheduled outages or while troubleshooting. When magnetostrictive transmitters are paired with MLIs, they offer an alternative to top-mounted level transmitter technologies while being isolated from vessel contents. For non-chemical or less critical applications in the water treatment process, ultrasonic (non-contact) transmitters are an excellent level measurement solution.

More Information

Learn more about instrumentation for every part of the steam generation cycle, from steam drum level control to the condensate recovery process and much more, at steamgen.magnetrol.com.

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Level and Flow Solutions for Natural Gas Dehydration Skids

Natural gas is one of the most widely used commercial gases because it is odorless, colorless, tasteless and non-toxic. However, it needs to undergo extensive purification before it can become pipeline-quality. Water vapor is the most common undesirable impurity found in natural gas. Left untreated, it can result in the formation of ice-like hydrates, which plug flow lines and natural gas processing equipment, causing severe operational problems. Two methods employed for natural gas dehydration are expansion refrigeration, or absorption through the use of solid or liquid desiccants.

Natural gas dehydration methods, especially glycol dehydration, can be fabricated as self-contained modular skid systems. This approach is increasing in popularity throughout many industries as a flexible, cost-effective and lower-impact way of conducting process operations. This post will discuss level and flow solutions for natural gas dehydration skids and is part of an occasional Magnetrol® blog series on modular skid systems.

Glycol Dehydration Skids
The use of ethylene glycol liquid desiccants is one of the most established and reliable techniques for natural gas dehydration. Liquid desiccants include diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TETRA EG). The dehydration process is sometimes separated into two skids: one for glycol absorption and another for glycol reconditioning.

Ethylene glycol flows downward from the top of a tower and meets a rising mixture of water vapor and hydrocarbon gases. Dry gas exits from the top of the tower while the glycol/water mixture is pumped out of the bottom. The glycol and water are separated, and the glycol is recycled.

natural gas dehydration

Level and Flow Applications

  1. Glycol Contactor
    Wet natural gas first flows through a glycol contactor to remove all liquid and solid impurities. The gas flows upward through the contactor where it is contacted and dried by glycol. The ‘pipeline-ready’ dried gas passes through a heat exchanger and into the application loop. Water-rich glycol is withdrawn from the bottom of the absorber via a level controller.
    Continuous Level: Eclipse® Model 706 Guided Wave Radar Transmitter
    Point Level: Tuffy® II Float Level Switch
  1. Flash Tank
    Skids are often provided with low pressure, three-phase flash separators to separate solution gas from the glycol and hydrocarbon condensate. A flash separator also removes up to 90% of methane emissions. The flash separator is installed on the rich glycol line between first pass of the glycol/glycol heat exchanger and the glycol filter bank.
    Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter
  1. Glycol Circulation Pump Protection
    Glycol recirculation pumps operating in a reduced or no-flow condition can overheat, rupture the pump’s seal, and disrupt the glycol reconditioning circuit. A flow switch along the pump’s discharge piping will actuate an alarm and shut down the pump when liquid flow drops below the minimum flow rate.
    Flow Alarm: Thermatel® Model TD1/TD2 Thermal Dispersion Switch for low-flow cutoff
  1. Exhaust Gas Flow Monitoring
    Exhaust gases emitted from the reboiler that are discharged directly to the atmosphere can be monitored by a mass flow transmitter. Because flow rates and gas compositions fluctuate, the mass flow transmitter can be used to obtain relative flow indication.
    Continuous Gas Flow: THERMATEL Model TA2 Thermal Dispersion Mass Flow Meter


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Eliminating Hidden Maintenance Costs With Condensate Recovery Process Level Control

The benefits of any condensate recovery system are well documented in industries relying on steam generation for their processes. Condensate has real value in that every gallon recovered spares the cost of additional makeup water, makeup water treatment and/or wasteful discharge to municipal or other systems. Oftentimes, it is the instrumentation, or lack thereof, that limits the performance of the overall system causing the condensate recovery process to fall short of financial expectations. Three areas of particular interest relative to efficiency when it comes to level controls are the condensate receiver and main condensate tanks, condensate pumps and associated valves as well as any shell and tube heat exchangers/condensers.

condensate recovery cycle

The Condensate Recovery Process

The condensate receiver tanks accept blow‐through steam and condensate from various steam process groups throughout a plant. Condensate is later pumped to the main condensate tank where it is stored pending reintroduction into the steam generation cycle. The shell and tube heat exchanger/condenser allows what would otherwise be waste energy to be recovered in the form of flash steam from the receiver tank to preheat makeup water or other process fluids through the heat of condensation. The resulting condensate drains back to the condensate or condensate receiver tank. 

The level transmitter on the condensate receiver tank facilitates the automatic management of the condensate level to ensure adequate capacity is available to accommodate (recover) condensate from various plant processes as well as maintaining sufficient headspace in the vessel for the creation of flash steam. Aside from being a critical asset for the plant, the condensate in the condensate receiver tank also protects valves and condensate pump seals from direct exposure to high temperature steam while maintaining a minimum head pressure on the pump. This prevents hardware damage, expensive maintenance and downtime of the receiver tank, and subsequent ripple effects on the steam generation cycle and makeup water requirements. Lastly, the level transmitter provides the control signals for the valves and condensate pump necessary to transfer condensate from the receiver to the main condensate tank, ensuring approximately 15 percent level retention for the aforementioned reasons. At this point, the main condensate tank level transmitters take over to manage boiler feed water supply to service steam generation demand.

Advantages of Guided Wave Radar and Magnetic Level Indicators

In order to ensure that the condensate recovery process has efficient level control, plants need to install high-quality level instrumentation. Guided wave radar (GWR) and magnetic level indicators are two technologies that can help eliminate hidden maintenance costs. GWR and magnetic level indicators are designed for high-temperature steam applications. Both technologies provide reliable measurement in a wide range of applications. They require no calibration and have setup wizards with full diagnostics for fast setup and fault isolation. Each instrument can be pre-configured for the specific application where it is being placed. The instrumentation hardware is simplified—and in the case of GWR, has no moving parts, eliminating instrument-induced errors. Using a GWR transmitter in conjunction with a magnetic level indicator provides level measurement for every aspect of the condensate recovery process.

With proper level instrumentation, the hidden maintenance costs in this process can be reduced or even eliminated. Learn more about GWR, magnetic level indicators and other technology for monitoring the steam generation cycle and condensate recovery process at steamgen.magnetrol.com.

steam generation

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