Applying Process Refractometers in Sugar Cane Processing

In-line process refractometer
Image courtesy Electron Machine Corp.

Sugar cane, after harvesting, requires processing within a limited time window to avoid sugar loss by inversion to glucose and fructose. The traditional two stage process, milling and processing, may be combined in a single modern production facility. Process refractometers can be found in both operations, making an optical measurement of a solution’s refractive index used to determine the concentration of dissolved solids.

To achieve high quality liquid and crystal sugars and contain production cost, refractometers are employed to deliver accurate in-line Brix and other measurements in the cane sugar refining and milling processes.

Specific uses of refractometers in sugar production are:

• Product flow adaptation to evaporator capacity to achieve energy savings.
• Extraction process optimization, minimizing the use of water that will need to be removed at the evaporator.
• Separation column feed juice control to adjust concentration to match capacity.
• Quality assurance check on liquid bulk sugar and molasses.
• Vacuum pan automatic and accurate seeding.
• Monitor supersaturation over complete strike of crystallization.

Share your process analytic and measurement challenges with the experts at application specialists, leveraging your own process knowledge and experience with their product application expertise to develop an effective solution.

MCE Technology for Chloride and Sulfate Analyzers

Mettler Toldeo, under their Thornton brand, employs Microfluidic Capillary Electrophoresis in the on-line measurement of chlorides and sulfates. This measurement system delivers actionable measurements of these potentially harmful water constituents, enabling timely corrective action to be taken and prevent damage to turbines and other steam utilization equipment.

The MCE technology is currently available on Thornton's 3000CS  Analyzer which provides on-line measurements every 45 minutes. The system reduces cost of ownership and provides faster results than methods requiring sampling and off-line processing.

Share your steam system and fluid analytical challenges with fluid process analytic specialists, combining your own knowledge and experience with their product application expertise to develop effective solutions.

Match the Right Temperature Sensor Configuration to the Application

Using a temperature sensor properly configured for
the application will result in enhanced process performance
Image courtesy Smart Sensors, Inc.

There are more temperature controlled operations than any of us could count in a lifetime. Each one exhibits an exclusive set of performance requirements and design challenges. Matching the means of temperature measurement, the control loop characteristics, and heat delivery method to the application are essential to achieving successful operation.

Step one is to measure the process temperature. This sounds simple until you start researching products and technologies for measuring temperature. Like the temperature controlled operations mentioned previously, there are more than you can count in a lifetime. To filter the possible candidates for temperature sensing devices, consider these aspects of your application and how well a particular sensor may fulfill your requirement.

• Response Time - How rapidly the sensor will detect a change in process temperature is a function of how the sensor is constructed and how it is installed. Most temperature sensors are enclosed or encapsulated to provide protection for the somewhat vulnerable sensing element. Greater mass surrounding the sensing element will slow sensor response. Whether the slower response time will adversely impact process operation needs to be considered. More consideration is due to the manner in which the temperature sensor assembly is installed. Not all applications involve a fluid in which the sensor assembly can be conveniently immersed, and even these applications benefit from careful sensor placement.
• Accuracy - Know what your process needs to be effective. Greater levels of accuracy will generally cost more, possibly require more care and attention to assure the accuracy is maintained. Accuracy is mostly related to the type of sensor, be it RTD, thermocouple, or another type.
• Sensitivity - Related to the construction, installation, and type of sensor, think of sensitivity as the smallest step change in process temperature that the sensor will reliably report. The needs of the process should dictate the level of sensitivity specified for the temperature sensor assembly.

Let's look at a very simple application.

Heat tracing of piping systems is a common application throughout commercial and industrial settings experiencing periods of cold weather. Electric heat trace installations benefit from having some sort of control over the energy input. This control prevents excessive heating of the piping or applying heat when none is required, a substantial energy saving effort. A temperature sensor can be installed beneath the piping's insulation layer, strapped to the pipe outer surface. One sensor design option available to improve the performance of the sensor is a surface pad. The surface pad is a metal fixture welded to the sensing end of a temperature sensor assembly. It can be flat, for surface temperature measurements, or angled for installation on a curved surface, like a pipe. The increased surface contact achieved with the surface pad promotes the conduction of heat to the sensor element from the heated pipe in our example. This serves to reduce and improve the response time of the sensor. Adding some thermally conductive paste between the pad and the pipe surface can further enhance the performance. While the illustration is simple, the concepts apply across a broad range of potential applications that do not allow immersion of the temperature assembly in a fluid.

A simple modification or addition of an option to a standard sensor assembly can deliver substantially improved measurement results in many cases. Share your temperature measurement requirements and challenges with a process measurement specialist. Leverage your own process knowledge and experience with their product application expertise.

Surface Temperature Sensors and Transmitters for Industrial Applications from Alliance Technical Sales, Inc.

Calibration of Process Instrumentation

Industrial temperature transmitter requires
periodic calibration to assure reliable performance
Image courtesy of Smart Sensors

Calibration is an essential part of keeping process measurement instrumentation delivering reliable and actionable information. All instruments utilized in process control are dependent on variables which translate from input to output. Calibration ensures the instrument is properly detecting and processing the input so that the output accurately represents a process condition. Typically, calibration involves the technician simulating an environmental condition and applying it to the measurement instrument. An input with a known quantity is introduced to the instrument, at which point the technician observes how the instrument responds, comparing instrument output to the known input signal.

Even if instruments are designed to withstand harsh physical conditions and last for long periods of time, routine calibration as defined by manufacturer, industry, and operator standards is necessary to periodically validate measurement performance. Information provided by measurement instruments is used for process control and decision making, so a difference between an instrument’s output signal and the actual process condition can impact process output or facility overall performance and safety.

In all cases, the operation of a measurement instrument should be referenced, or traceable, to a universally recognized and verified measurement standard. Maintaining the reference path between a field instrument and a recognized physical standard requires careful attention to detail and uncompromising adherence to procedure.

Instrument ranging is where a certain range of simulated input conditions are applied to an instrument and verifying that the relationship between input and output stays within a specified tolerance across the entire range of input values. Calibration and ranging differ in that calibration focuses more on whether or not the instrument is sensing the input variable accurately, whereas ranging focuses more on the instrument’s input and output. The difference is important to note because re-ranging and re-calibration are distinct procedures.

In order to calibrate an instrument correctly, a reference point is necessary. In some cases, the reference point can be produced by a portable instrument, allowing in-place calibration of a transmitter or sensor. In other cases, precisely manufactured or engineered standards exist that can be used for bench calibration. Documentation of each operation, verifying that proper procedure was followed and calibration values recorded, should be maintained on file for inspection.

As measurement instruments age, they are more susceptible to declination in stability. Any time maintenance is performed, calibration should be a required step since the calibration parameters are sourced from pre-set calibration data which allows for all the instruments in a system to function as a process control unit.

Typical calibration timetables vary depending on specifics related to equipment and use. Generally, calibration is performed at predetermined time intervals, with notable changes in instrument performance also being a reliable indicator for when an instrument may need a tune-up. A typical type of recalibration regarding the use of analog and smart instruments is the zero and span adjustment, where the zero and span values define the instrument’s specific range. Accuracy at specific input value points may also be included, if deemed significant.

The management of calibration and maintenance operations for process measurement instrumentation is a significant factor in facility and process operation. It can be performed with properly trained and equipped in-house personnel, or with the engagement of subcontractors. Calibration operations can be a significant cost center, with benefits accruing from increases in efficiency gained through the use of better calibration instrumentation that reduces task time.

Measurement of Oxygen in Processing Applications

This optical oxygen sensor is one of many oxygen
measurement devices
Image courtesy Mettler-Toledo

The measurement of oxygen is used throughout many industrial processing operations. Knowing about oxygen measurement technology can lead to better measurement performance.

Mettler-Toledo, a recognized leader in process analytical measurement technology, has authored a comprehensive guide to oxygen measurement. Some of the covered topics include:

• Theoretical background of oxygen measurement
• Calibration of oxygen sensors
• Description of oxygen measurement technologies
• Common challenges with oxygen measurements
• And more

A copy of the guide is included below. Share your process analytical requirements and challenges with measurement experts, combining your own knowledge and experience with their product application expertise to develop effective solutions. Ask for your own copy of the guide, too.

Guide to Oxygen Measurement in Industrial Process Applications from Alliance Technical Sales, Inc.

Direct Reading Level Indicator Gauge for Process Tanks

Direct reading level gauge continuously indicates
tank liquid level
Image courtesy Jogler

Anytime there is a process tank, there is a need to know how full it may be. There are numerous methods and technologies that can be applied, with varying levels of complexity and accuracy, to provide a measure and indication of tank liquid level.

A direct reading tank level gauge is essentially an extension of the tank that provides a visible indication of liquid level. The level is not inferred from a pressure reading or tank weight, nor is it represented by the movement of a float or other device. The actual process liquid can be seen by an operator or technician by looking at the clear display area of the gauge.

A direct reading level gauge connects to tank fittings at significantly high and low points along the tank side wall. The connections permit process liquid to flow into the gauge, with the level in the gauge being the same as that in the tank. A scale on the gauge provides a reference point for liquid level that can be recorded or used in other ways in the process. The simple device has no moving parts, requires no calibration, demands little to no maintenance. It can be the primary level indicating device for a manually operated fill, or act as a backup or local indicator for an automated process.

There are pressure limitations for these indicators. Higher pressure applications, or those with liquids that may foul the clear viewing area of the indicator are better handled with a magnetic level indicator. Like all instruments, proper application is the key to getting the best performance.

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

Level Gauges, Flow Sight Glasses, and Analyzers from Alliance Technical Sales, Inc.

Heated Impulse Lines on Pressure Gauges and Transmitters

Successive cutaway view of self-regulating heat trace

cable showing various layers of material

Courtesy BriskHeat

Temperature of the environment surrounding process equipment and instruments can sometimes have a deleterious impact on its function. A common example is cold weather impact on the impulse lines connecting pressure gauges or transmitters to process piping in outdoor or unheated locations. While the process lines may be large, with sufficient mass flow and insulation to prevent freezing, this may not be the case for small diameter impulse lines. Liquid freezing in cold weather conditions can be a threat to process operation, depending on the type of liquid being used. A safeguard exists for impulse lines where the lines can be traced with a heat source, allowing for counteraction of the environmental conditions and maintenance of proper operation.

There are a number of ways to deliver heat to an impulse line. Recognize two essential goals, with the first being to prevent freezing or other changes to the fluid in the line that would impact the response or accuracy of the instrument reading. The second goal is related to the heat tracing itself. The delivered heat must not be great enough to impact the fluid in the impulse line and generate a false pressure reading. Optimally, delivering heat in a fashion that is limited to what is necessary to maintain the impulse line fluid in an ideal working state is best.

One example of heat tracing an impulse line is through the placement of a tube or small diameter pipe, located in close proximity to line, through which low pressure steam flows. Insulation is applied to the bundle and the steam line serves as a heat source. The tube transfers heat to the impulse line when steam flows. After the steam heats the impulse line, a steam trap accompanying the system collects condensate for return to the boiler. It is also conceivable that the steam line could ultimately vent to atmosphere, with no condensate return. There are a number of concerns that must be addressed in the design of the steam portion of this scenario, since it would be necessary to keep any condensate from freezing under all anticipated operating conditions, including process shutdown.

A second common solution for freeze protection of impulse lines is through the installation of electric heat tracing. Two-wire cable serves as protection against the cold. When powered, the heat from the cable keeps the line warm. Electric heat tracing is available in a broad range of physical configurations, including cables, tape, blankets, and other flexible and solid shapes. Control of the electric heat system can be accomplished with an external controller and sensor, or a self-regulating heat trace cable can be used. As with a steam heating system, there are some specific considerations for electric heat tracing. Thermal insulation is still considered a best practice. Electric power must be delivered to the installation, and a means of monitoring heat trace performance for faults or failure should be included in the design.

Share your heat tracing requirements and challenges for process piping and other industrial applications with a product specialist. There are many options and product variants from which to choose. A consultation can help direct you to the best solution.

Water Quality Testing - Turbidity Standards

ProCal turbidity standards are suitable for use
with instruments from other manufacturers.
Image Courtesy HF Scientific

Turbidity is a commonly measured indicator of water quality. Regardless of the instrument being used, frequent and regular calibration is part of the procedure assuring accurate and traceable results that may be used as evidence of regulatory compliance.

Calibration requires the use of a prepared sample of a known value. HF Scientific, manufacturer of water quality instrumentation, reagents, and standards, provides high quality premixed turbidity standards that are suitable for use with their instruments, as well as those of several other manufacturers.

Share your water quality analysis requirements and challenges with process analytic specialists, combining your own experience and knowledge with their product application expertise to develop effective solutions.

Turbidity Standards for Turbidity Measurement from Alliance Technical Sales, Inc.

Liquid Level Measurement Using Hydrostatic Pressure

Hydrostatic pressure can be used to measure liquid level
in tanks or other vessels.

Pressure measurement is an inferential way to determine the height of a column of liquid in a vessel in process control. The vertical height of the fluid is directly proportional to the pressure at the bottom of the column, meaning the amount of pressure at the bottom of the column, due to gravity, relies on a constant to indicate a measurement. Regardless of whether the vessel is shaped like a funnel, a tube, a rectangle, or a concave polygon, the relationship between the height of the column and the accumulated fluid pressure is constant. Weight density depends on the liquid being measured, but the same method is used to determine the pressure.

A common method for measuring hydrostatic pressure is a simple gauge. The gauge is installed at the bottom of a vessel containing a column of liquid and returns a measurement in force per unit area units, such as PSI. Gauges can also be calibrated to return measurement in units representing the height of liquid since the linear relationship between the liquid height and the pressure. The particular density of a liquid allows for a calculation of specific gravity, which expresses how dense the liquid is when compared to water. Calculating the level or depth of a column of milk in a food and beverage industry storage vessel requires the hydrostatic pressure and the density of the milk. With these values, along with some constants, the depth of the liquid can be calculated.

The liquid depth measurement can be combined with known dimensions of the holding vessel to calculate the volume of liquid in the container. One measurement is made and combined with a host of constants to determine liquid volume. The density of the liquid must be constant in order for this method to be effective. Density variation would render the hydrostatic pressure measurement unreliable, so the method is best applied to operations where the liquid density is known and constant.

Interestingly, changes in liquid density will have no effect on measurement of liquid mass as opposed to volume as long as the area of the vessel being used to store the liquid remains constant. If a liquid inside a vessel that’s partially full were to experience a temperature increase, resulting in an expansion of volume with correspondingly lower density, the transmitter will be able to still calculate the exact mass of the liquid since the increase in the physical amount of liquid is proportional to a decrease in the liquid’s density. The intersecting relationships between the process variables in hydrostatic pressure measurement demonstrate both the flexibility of process instrumentation and how consistently reliable measurements depend on a number of process related factors.

Solutions to process instrumentation and measurement challenges are most effective when developed in concert with a product application specialist. The combination of user knowledge and experience with product application expertise will lead to a successful project.

Online Chlorine Monitor

Online chlorine and TRO analyzer
Photo courtesy HF Scientific

Online chlorine analyzers are utilized throughout industrial and commercial applications for the monitoring and control of chlorine in potable water, seawater, swimming pool water, process water, waste water, food processing, pulp and paper, and more. Every application benefits from instrumentation delivering accurate and reliable results with a minimum amount of human intervention.

Many instruments are available, with each possibly having a set of construction and operational features that will make it an advantageous choice for a particular application or installation.

The CLX-XT2 online chlorine monitor from HF Scientific is optimized for high temperature marine applications and provides extended reagent life and unattended operation of up to 90 days. The instrument includes communications and output signals that can be used to control chemical feed pumps or provide alarm function.

More detail on the unit is provided below. Share your analytical measurement challenges with application specialists, combining your own knowledge and experience with their instrumentation application expertise to develop effective solutions.

Online Chlorine and TRO Monitor from Classic Controls, Inc.

Water Quality Analysis – Constituent Survey Part 3

Industrial steam turbines can be negatively impacted
by silica

What we know as “water” can consist of many non-H2O components in addition to pure water. This three part series has touched on some of the constituents of water that are of interest to various industrial processors. The first installment reviewed dissolved oxygen and chloride. The second article covered sulfates, sodium, and ammonia.

To conclude the three part series on water quality analysis in process control related industrial applications we examine silica, another element which in sufficient quantities can become a confounding variable in water for industrial use. In natural settings, silica, or silicon dioxide, is a plentiful compound. Its presence in water provides a basis for some corrosion-inhibiting products, as well as conditioners and detergents. Problems arise, however, when high concentrates of silica complicate industrial processes which are not designed to accommodate elevated levels. Specifically, silica is capable of disrupting processes related to boilers and turbines. In environments involving high temperature, elevated pressure, or both, silica can form crystalline deposits on machinery surfaces. This inhibits the operation of turbines and also interferes with heat transfer. These deposits can result in many complications, ranging through process disruption, decreased efficiency, and resources being expended for repairs.

The silica content in water used in potentially affected processes needs to be sufficiently low in order to maintain rated function and performance. Silica analyzers provide continuous measurement and monitoring of silica levels. The analyzers detect and allow mitigation of silica in the initial stages of raw material acquisition or introduction to prevent undue disruption of the process. Additionally, a technique called power steam quality monitoring allows for the aforementioned turbine-specific inhibition – related to silica conglomerates reducing efficacy and physical movement – to be curtailed without much issue. The feedwater filtration couples with a low maintenance requirement, resulting in reduced downtime of analytic sequences and a bit of increased peace of mind for the technical operator.

While silica and the other compounds mentioned in this series are naturally occurring, the support systems in place to expertly control the quality of water is the most basic requirement for harvesting one of the earth’s most precious resources for use. As a matter of fact, the identification and control of compounds in water – both entering the industrial process and exiting the industrial process – demonstrates key tenets of process control fundamentals: precision, accuracy, durability, and technological excellence paired with ingenuity to create the best outcome not just one time, but each time.

The measurement of the various contaminating constituents of process water requires special equipment and techniques. Share your water quality measurement requirements and challenges with fluid process specialists, combining your own knowledge and experience with their product application expertise to develop effective solutions.

Water Quality Analysis – Constituent Survey (Part 2)

Sewage treatment is but one area where water quality
measurement is employed

It would be difficult to understate the role and importance of water in industrial processing, even our own biological existence. In the first installment of this series, the roles of dissolved oxygen and chlorides were covered.

Continuing the examination of water quality monitoring in municipal and industrial processes, another key variable which requires monitoring for industrial water use is sulfate. Sulfate is a combination of sulfur and oxygen, salts of sulfuric acid. Similarly to chlorides, they can impact water utilization processes due to their capability for corrosion. The power generation industry is particularly attuned to the role of sulfates in their steam cycle, as should be any boiler operator. Minerals can concentrate in steam drums and accelerate corrosion. Thanks to advancements in monitoring technology, instruments are available which monitor for both chlorides (covered in the previous installment in this series) and sulfates with minimal supervision needed by the operator, ensuring accurate detection of constituent levels outside of an acceptable range. Ionic separation technologies precisely appraise the amount of sulfate ions in the stream, allowing for continuous evaluation and for corrective action to be taken early-on, avoiding expensive repairs and downtime.

Another substance worthy of measurement and monitoring in process water is sodium. Pure water production equipment, specifically cation exchange units, can be performance monitored with an online sodium analyzer. Output from the cation bed containing sodium, an indication of deteriorating performance, can be diverted and the bed regenerated. Steam production and power generation operations also benefit from sodium monitoring in an effort to combat corrosion in turbines, steam tubes, and other components. Sodium analyzers are very sensitive, able to detect trace levels.

Ammonia is comprised of nitrogen and hydrogen and, while colorless, carries a distinct odor. Industries such as agriculture utilize ammonia for fertilizing purposes, and many other specializations, including food processing, chemical synthesis, and metal finishing, utilize ammonia for their procedural and product-oriented needs. An essential understanding of ammonia, however, includes the fact that the chemical is deadly to many forms of aquatic life. Removing ammonia from industrial wastewater is a processing burden of many industries due to the environmental toxicity.

Methods for removing ammonia from wastewater include a biological treatment method called ‘conventional activated sludge’, aeration, sequencing batch reactor, and ion exchange. Several methods exist for in-line or sample based measurement of ammonia concentration in water. Each has particular procedures, dependencies, and limitations which must be considered for each application in order to put the most useful measurement method into operation.

As water is an essential part of almost every facet of human endeavor and the environment in which we all dwell, the study and application of related analytics is an important component of many water based processes. The variety of compounds which can be considered contaminants or harmful elements when dissolved or contained in water presents multiple challenges for engineers and process operators.

Alliance Technical Sales specializes in the instruments, equipment, and supplies utilized to analyze water and other liquids employed throughout commercial and industrial operations.

Water Quality Analysis – Constituent Survey (Part 1)

Many industrial and commercial processes rely on
specific water quality requirements

Of all the raw materials available for human consumption – aside from the air we breathe – the most vital component of life on earth is water. In addition to the global need for humans to drink water in order to survive, the use of water is essential in a myriad of industries relating to process control. Whether the goal is the production or monitoring of pure water for industrial use, or the processing of wastewater, the ability to measure the presence and level of certain chemical constituents of water is necessary for success.

In order to use water properly, industrial professionals combine state of the art analyzers with technical expertise to evaluate water quality for use or disposal. Two essential values of process control are ensuring elements of a control system are accurate and secure, and, furthermore, that they are accurate and secure for each product every time. By properly vetting water in industry, engineers and other personnel in fields such as pharmaceuticals, chemical, food & beverage, brewing, power, and microelectronics are able to maintain standards of production excellence and conform with regulatory requirements related to water quality.

The amount of dissolved oxygen present in water can correlate with the degree of movement at an air-water interface, also being impacted by pressure, temperature, and salinity. Excessive or deficient dissolved oxygen levels in industrial process waters may have an impact on process performance or end product quality. Likely, the most common application for dissolved oxygen measurement is in the evaluation of wastewater for biological oxygen demand. The primary function of dissolved oxygen in wastewater is to enable and enhance the oxidation of organic material by aerobic bacteria, a necessary step in treatment.

To measure dissolved oxygen, specialized sensors and companion instruments are employed that require careful maintenance and trained technical operators. The level of measurement precision varies depending on the industry employing the technology, with numerous applications also being found in the food & beverage and pharmaceutical industries. In-line continuous measurement is used in wastewater processing to determine if the dissolved oxygen remains in a range that supports the bacteria necessary for biodegradation.

Chloride concentration in wastewater is strictly regulated. Industrial and commercial operation effluent can be regulated with respect to allowable chloride content. While commonly found in both streams and wastewater, chlorides, in large amounts, can present challenges to water utilization or processing facilities. Chloride levels impact corrosion, conductivity, and taste (for industries in which such a variable is paramount). In a process system, having an essential component marred due to elevated quantities of a substance could reverberate into any end-product being manufactured. Chloride analyzers, some of which can also detect and monitor other water characteristics, serve as important tools for water consuming facilities to meet regulatory standards for effluent discharge or internal quality standards for recycling.

There are other constituents of what we refer to as “water” that are subject to measurement and monitoring for a range of institutional, industrial, and municipal applications. Those will be explored in the next part of this article series.

The measurement of dissolved oxygen or chloride concentration requires special equipment and techniques. Share your water quality measurement requirements and challenges with fluid process specialists, combining your own knowledge and experience with their product application expertise to develop effective solutions.

Common Industrial and Commercial Process Heating Methods

Many industrial processes utilize heat as an energy input

Many industrial processes involve the use of heat as a means of increasing the energy content of a process or material. The means used for producing and delivering process heat can be grouped into four general categories.

• Steam
• Fuel
• Electric
• Hybrid

The technologies rely upon conduction, convection, or radiative heat transfer mechanisms, soley or in combination, to deliver heat to a substance. In practice, lower temperature processes tend to use conduction or convection. Operations employing very high temperature rely primarily on radiative heat transfer. Let's look at each of the four heating methods.

STEAM

Steam based heating systems introduce steam to the process either directly by injection, or indirectly through a heat transfer device. Large quantities of latent heat from steam can be transferred efficiently at a constant temperature, useful for many process heating applications. Steam based systems are predominantly for applications requiring a heat source at or below about 400°F and when low-cost fuel or byproducts for use in generating the steam are accessible. Cogeneration systems (the generation of electric power and useful waste heat in a single process) often use steam as the means to produce electric power and provide heat for additional uses. While steam serves as the medium by which heat energy is moved and delivered to a process or other usage, the actual energy source for the boiler that produces the steam can be one of several fuels, or even electricity.

FUEL

Fuel based process heating systems, through combustion of solid, liquid, or gaseous fuels, produce heat that can be transferred directly or indirectly to a process. Hot combustion gases are either placed in direct contact with the material (direct heating via convection) or routed through tubes or panels that deliver radiant heat and keep combustion gases separate from the material (indirect heating). Examples of fuel-based process heating equipment include furnaces, ovens, red heaters, kilns, melters, and high-temperature generators. The boilers producing steam that was described in the previous section are also an example of a fuel based process heating application.

ELECTRIC

Electric process heating systems also transform materials through direct and indirect means. Electric current can be applied directly to suitable materials, with the electrical resistance of the target material causing it to heat as current flows. Alternatively, high-frequency energy can be inductively coupled to some materials, resulting in indirect heating. Electric based process heating systems are used for heating, drying, curing, melting, and forming. Examples of electrically based process heating technologies include electric arc furnace technology, infrared radiation, induction heating, radio frequency drying, laser heating, and microwave processing.

HYBRID

Hybrid process heating systems utilize a combination of process heating technologies based on different energy sources or heating principles, with a design goal of optimizing energy performance and overall thermal efficiency. For example, a hybrid steam boiler may combine a fuel based boiler with an electric boiler to take advantage of access to low off-peak electricity cost. In an example of a hybrid drying system, electromagnetic energy (e.g., microwave or radio frequency) may be combined with convective hot air to accelerate drying processes; selectively targeting moisture with the penetrating electromagnetic energy can improve the speed, efficiency, and product quality as compared to a drying process based solely on convection, which can be rate limited by the thermal conductivity of the material. Optimizing the heat transfer mechanisms in hybrid systems offers a significant opportunity to reduce energy consumption, increase speed and throughput, and improve product quality.

Many heating applications, depending on scale, available energy source, and other factors may be served using one or more of the means described here. Determining the best heating method and implementation is a key element to a successful project. Alliance Technical Sales specializes in electric heating applications and facets of the industrial production of steam. Share your process and project challenges with them and combine your facilities and process knowledge and experience with their product application expertise to develop effective solutions.

Automatic pH Sensor Cleaning and Calibration Saves Time and Cost

Automated pH sensor cleaning and calibration
with EasyClean 400
Courtesy Mettler Toledo

Measurement of pH is a common analytical operation in liquid processing. Whether chemical or wastewater operations, pH measurement provides useful information about process condition.

The sensors used for measuring pH can require care and maintenance, in the form of cleaning and calibration, to maintain peak performance. Traditionally, these operations have been performed manually by trained technicians. The task, though, is a good candidate for automation to provide cost savings and uniformity for sensor cleaning and calibration.

Mettler Toledo manufacturers four different automated cleaning and calibration systems for their analytical sensors. The offering ranges from simple water rinsing or compressed air cleaning to prevent build up to fully automated cleaning and calibration systems requiring little in the way of human intervention.

The technical data sheet below provides details about the fully automated system. Share your analytical measurement challenges and requirements with application specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Automated pH Sensor Cleaning and Calibration from Alliance Technical Sales, Inc.

Mounting Adaptions Expand Applications for Tunable Diode Laser Gas Analyzers

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.

Folded Path Tunable Diode Laser Gas Analyzers from Alliance Technical Sales, Inc.

Retractable Sensor Housing for Analytical 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.

Retractable Sensor Housings for Analytical Sensors from Alliance Technical Sales, Inc.

Activated Carbon Adsorber as Backup for 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.

Magnetostrictive Level Transmitter

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.

Magnetostrictive Level Transmitter for Industrial Process Measurement from Alliance Technical Sales, Inc.

HF Scientific - Water Quality Measurement

Alliance Technical Sales recently commenced representation of HF Scientific, a manufacturer of water quality instrumentation and chemistry products. The arrangement complements the already broad line of analytical products offered by Alliance for fluid processing and analysis across a wide range of applications and industries.