Wednesday, May 31, 2017

Mounting Adaptions Expand Applications for Tunable Diode Laser Gas Analyzers

tunable diode laser gas analyzer with retroreflector adapter
Tunable diode laser gas analyzer with retroflector
requires no special aiming and puts the source
and detector on the same side of the pipe.
Courtesy Mettler Toledo
Gas analysis is an important part of production, quality control, safety, efficiency, or legal compliance in many industrial operations. Reliable and accurate information about the concentration of certain gas components enables operators to properly control processes and regulate output.

A tunable diode laser gas analyzer (TDL) is essentially an application of absorption spectroscopy. The laser light source can be adjusted to the absorption wavelength of the target gas molecule. The light passes through the gas and is collected and measured by a detector. Based upon known properties of the target gas molecule, its concentration can be determined. The technology provides suitable accuracy, delivers real time measurement data, and in many cases requires little maintenance. Of course, applying technology in the field can present unique site specific challenges.

Dust, other particulates, distance related to pipe diameter, pressure, and temperature can impact the instruments ability to deliver reliable measurements. Additionally, installations using opposing emitters and detectors in a "cross pipe" configuration can have difficulty in achieving and maintaining proper alignment. Solutions are at hand for many of these previously intractable applications. Integrating the light source and detector into a single unit with lighter weight and smaller size enables a less complicated installation scenario. There are other adaptions made to the instrument that overcome many of the commonly encountered difficulties when installing a TDL into an existing or new system.

Mettler Toledo, innovator in the TDL field, authored a white paper illustrating some of the installation challenges and how they can be successfully and easily overcome using a properly adapted tunable diode laser gas analyzer. The paper is included below, taking only a few minutes to read. It's well worth the time spent.

Share your process analytical requirements and challenges with specialists in process analytical solutions, combining your own process knowledge and experience with their product application expertise to reach a successful outcome.


Tuesday, May 23, 2017

Retractable Sensor Housing for Analytical Sensors

retractable sensor housing for Mettler Toledo Thornton Ingold sensors
The retractable sensor housings are available in several configurations
Process analytical sensors generally require some "care and feeding" to maintain specified performance levels. This maintenance can require removal of the sensor from the process in which it is inserted. Clearly, it is seldom advantageous to shut down a process for maintenance when it could otherwise remain in operation. The challenge - how to service the pH, redox, conductivity, or dissolved oxygen sensors without process interruption.

Mettler Toledo, under their Ingold brand of process analytic products, provides a solution in the form of a retractable sensor housing. Models accommodate sensors for pH, redox, conductivity, and dissolved oxygen. The housings are designed to enable safe retraction of the sensor from the process, with in place sensor cleaning or further maintenance operations made simple with the process remaining in operation.

The document below provides additional detail. Share your process analytical challenges with an application expert, combining your own process experience and knowledge with their product application expertise to develop effective solutions.



Friday, May 19, 2017

Activated Carbon Adsorber as Backup for Thermal Oxidizer

diagram of activated carbon adsorber as backup to thermal oxidizer
Activated carbon backup for thermal oxidizer
Courtesy Process Combustion Corporation
Volatile organic compounds (VOC) are one class of air pollutants with emission limits described in law. Industrial plants that produce VOC as part of their processing must take steps for the removal or destruction of the pollutant prior to discharge in the atmosphere.

Thermal oxidization systems are routinely employed to remove volatile organic compounds from industrial emission air streams. The systems deliver some operational advantages.
  • Ease of operation
  • Flexibility to match process changes
  • Continuous operation without need to change disposables
  • No byproducts requiring further handling or disposal
  • Simple process with small number of components
  • Broad application range for VOC
Operation of the thermal oxidation system is essential to maintaining continuance of plant operations, since the oxidizer continually processes plant output. The potential costs associated with a work stoppage due to malfunction or maintenance of the thermal oxidation system may make the installation of a backup VOC processor a prudent business decision.

Activated carbon is a well recognized material for the capture of VOC. Along with the addition of other sorbents, the scavenging profile of the fixed adsorbent bed can be tailored to specific process demands. The activated carbon processor is essentially a filtration unit that traps the target compounds as discharged process air flows through the unit. It is a simple effective system with known performance parameters

An activated carbon adsorber will serve as an effective backup unit for a thermal oxidizer. The limitations of the activated carbon unit are its rated flow rate for which VOC removal is defined, as well as the fixed holding capacity of the adsorbent itself. Once spent, the adsorbent must be regenerated or replaced. In selecting a properly sized backup VOC adsorber, these factors should be taken into account.

Share your VOC pollution control challenges with specialists in the field. The combination of your own process knowledge and experience with their product application expertise will produce effective solutions.

Friday, May 12, 2017

Magnetostrictive Level Transmitter

magnetostrictive level transmitter for process measurement and control
Magnetostrictive level transmitter, showing electronics (head)
mounting plate, sensing tube, and float.
Courtesy Jogler
The numerous level control technologies, methods, and instruments all have an application range or niche where they provide a feature set and performance advantageous to other measurement means. The particular set of attributes that can push one instrument over the top in the selection process is specific to each user and application.

Magnetostrictive level transmitters provide a continuous signal indicating liquid level in a vessel. They should not be confused with what are called magnetic level gauges, an instrument that locally provides a visual indication of liquid level.

Magnetostrictive level measurement employs a precise measuring of the transit time for an electric pulse travelling on a wire extending down an enclosed tube oriented vertically in the subject media. A magnetized float on the exterior of the tube moves with the liquid surface. The float’s magnetic field interacts with a magnetic field produced along the wire to generate a return signal to the transmitter head. Processing the time from emission to return provides a measure of distance to the liquid surface.

These level transmitters offer good accuracy and ease of installation and maintenance. They are best applied with relatively clean fluids. Media that will impede the free movement of the float along the sensing tube should be avoided. Magnetostrictive level instruments are often employed alongside, or integrated with, a magnetic level gauge. The magnetic gauge provides a local indication of tank level, while the magnetostrictive transmitter delivers a level signal to monitoring and control equipment.

Share your level measurement requirements and challenges with a process measurement specialist, combining your own process knowledge and experience with their product application expertise to develop effective solutions.


Thursday, May 4, 2017

Keep Condensation at Bay in Your Facility

condensation on glass with cold drink
Condensation accumulates water on
the exterior of this cold glass
Condensation, the accumulation of liquid water on a surface through contact with humid air, can be harmless in some settings, an undesirable or even damaging occurrence in others. In situations where condensation is undesirable, taking steps to prevent the conditions that preclude its formation are relatively simple and deliver a good payback.

What is condensation? In general usage, the term refers to the formation of liquid water droplets that occurs when humid air contacts a cooler surface. It is the liquid moisture that accumulates on the exterior of a glass containing a cold drink. Properly, the term condensation names the process of a vapor changing to a liquid. It is the opposite of evaporation. Condensate (note the different word form) is the liquid accumulated through the condensation process. This article is limited to condensate that forms when atmospheric air contacts a cold surface, so the general usage term condensation will be used.

Where can it happen? Water vapor is contained in air when it has sufficient energy to remain in the vaporous state. Remove some of that heat energy and a calculable quantity of the water vapor will no longer be supported, condensing into liquid water. The temperature at which any given quantity of air will start to shed some of its water vapor content is primarily determined by the concentration of water vapor in the air. A higher water vapor content will result in a higher temperature at which the water vapor will begin to condense. In everyday terms, higher relative humidity leads to a higher temperature at which condensation takes place.

What is the range of impact? Condensation appears to us as water that almost magically manifests on a surface. It seems to come right out of thin air.....because that is where it came from. It can form locally or broadly throughout an area. The potential impact of condensation arises from the fact that it is liquid water. Anything that will be damaged by water will be adversely impacted by condensate formation on its surface. This includes rust and corrosion of metals, spotting on material or object surfaces, the promotion of mold and mildew, and a wide range of other undesirable effects. Accumulated condensate on overhead objects or surfaces can eventually drip onto equipment, materials, and work areas situated below. Puddles of water on a floor can also create a hazard.

Prevention is the best, maybe the only cure.

How to prevent condensate formation?

  • Ventilation - If there is a source of moisture in a space that is elevating the humidity, continually diluting the space moisture content by introducing fresh air with a lower moisture content may be an effective prevention method. Ventilation relies on the fresh air conditions always being sufficient for moisture reduction without creating some other adverse impact on the space. For example, ventilating with outdoor air may be effective throughout only part of the year. Without a reliable source of ventilation air with known conditions, this method may not always deliver the desired results. Ventilation is an active method that requires energy to move the ventilation air. Additional energy may be required to adjust the temperature or moisture conditions of the ventilation air, as well.
  • Insulation - The surfaces where condensation occurs can be isolated from the moist air by insulating materials. This is common with HVAC ductwork and process piping. If done properly, this method is effective. The goal is to create a new surface that does not exhibit the cooler temperatures of the isolated surface. The thickness and reduced thermal conductivity of the insulation material will achieve this. There is also a vapor barrier on the exterior of the insulation that prevents entry of moisture laden air into the insulation material.  It is important the the vapor barrier installed as part of the insulating process remain intact and undamaged. Otherwise, water vapor will enter the insulating material and condense, with the potential for a localized failure of the insulating scheme. Insulation is a passive measure that requires no added energy to remain effective.
  • Dehumidification - Outright reduction of moisture contained in the air of an enclosed space will reduce the temperature at which water vapor condenses. Dehumidification machinery is available in a wide range of sizes and performance levels to suit almost any scenario. Though it requires energy to operate, the machinery is generally simple and operates automatically to maintain a space condition that will not support condensation.
  • Heating - Some cases can be most effectively treated using the application of a small amount of heat to the surface where condensation forms. This active method can be very effective when the need is localized. Also, surface heaters can be fabricated that will fit where insulation will not, and the heating assemblies may be more resistant to impact and damage than insulating materials. Proper control of heating equipment will minimize energy consumption.
Implementing an effective plan to combat condensation involves the identification of the conditions that promote its formation in your own facility. Selecting the best prevention plan calls for consideration of costs and reliability of various schemes. Active methods, such as heating or dehumidification, have some capacity for adjustment if conditions change over time. Insulation plans should have sufficient headroom or safety factor in their design to accommodate unforeseen conditions.