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.