Water Quality Analysis – Constituent Survey Part 3

Water quality can be a concern for process input or effluent

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.

New Pulsar R86 Non-contact Radar Level Transmitter From Magnetrol

Magnetrol's new non-contact radar level transmitter,,
Pulsar R86
Courtesy Magnetrol

Level measurement is a part of countless industrial processes and installations. Accurate measurement of contained solids or liquid enhances safety and operational efficiency, both of which contribute to the bottom line.

Magnetrol, globally recognized innovator in flow and level measurement, recently released its latest version of non-contact radar level measuring instruments. The Pulsar R86 transmitter operates in the 26GHz range, delivering a smaller wavelength with improved resolution, smaller antenna, and a narrower beam. Other unique innovations have been incorporated into the instrument to simplify installation and application.

The R86 is suitable for a broad range of applications across almost every industry. On board diagnostics are incrementally advanced to provide best performance and deliver the information needed to maintain proper operation.

The latest information on the Pulsar R86 is included below. Reach out to process measurement specialists and share your measurement challenges and requirements. Combining your own process knowledge and experience with their product application expertise will result in an effective solution.

Magnetrol Non-Contact Radar Level Transmitter Pulsar R86 from Miller Energy, Inc.

Water Quality Analysis – Constituent Survey (Part 2)

Water can contain many contaminants

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.

The detection and measurement of water constituents can pose challenges to plant operators. Share your requirements with instrumentation experts, and combine your own process knowledge and experience with their product application expertise to formulate an effective solution.

Water Quality Analysis – Constituent Survey (Part 1)

Water quality analysis is utilized at sewage treatment plants,
but at many other industrial facilities, too.

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.

Primary Flow Elements - Orifice Plate

A simple orifice plate
Courtesy Flow Lin

An orifice plate, at its simplest, is a plate with a machined hole in it. Carefully control the size and shape of the hole, mount the plate in a fluid flow path, measure the difference in fluid pressure between the two sides of the plate, and you have a simple flow measurement setup. The primary flow element is the differential pressure across the orifice. It is the measurement from which flow rate is inferred. The differential pressure is proportional to the square of the flow rate.

An orifice plate is often mounted in a customized holder or flange union that allows removal and inspection of the plate. A holding device also facilitates replacement of a worn orifice plate or insertion of one with a different size orifice to accommodate a change in the process. While the device appears simple, much care is applied to the design and manufacture of orifice plates. The flow data obtained using an orifice plate and differential pressure depend upon well recognized characteristics of the machined opening, plate thickness, and more. With the pressure drop characteristics of the orifice fixed and known, the measuring precision for differential pressure becomes a determining factor in the accuracy of the flow measurement.

There are standards for the dimensional precision of orifice plates that address:

• Circularity of the bore
• Flatness
• Parallelism of the faces
• Edge sharpness
• Surface condition

Orifice plates can be effectively "reshaped" by corrosion or by material deposits that may accumulate from the measured fluid. Any distortion of the plate surface or opening has the potential to induce measurable error. This being the case, flow measurement using an orifice plate is best applied with clean fluids.

Certain aspects of the mounting of the orifice plate may also have an impact on its adherence to the calibrated data for the device. Upstream and downstream pipe sections, concentric location of the orifice in the pipe, and location of the pressure measurement taps must be considered.

Properly done, an orifice plate and differential pressure flow measurement setup provides accurate and stable performance. Share your flow measurement challenges of all types with a process measurement specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Wireless Transmitters In Process Measurement and Control

Wireless industrial temperature transmitter
Courtesy Yokogawa

In process control, various devices produce signals which represent flow, temperature, pressure, and other measurable elements of the process. In delivering the process value from the measurement point to the point of decision, also known as the controller, systems have traditionally relied on wires. More recently, industrial wireless networks have evolved, though point-to-point wireless systems are still available and in use. A common operating protocol today is known as WirelessHARTTM, which features the same hallmarks of control and diagnostics featured in wired systems without any accompanying cables. Other wireless standards are employed in industrial settings, as well.

Wireless devices and wired devices can cohabitate the same network. The installation costs of wireless networks are decidedly lower than wired networks due to the reduction in labor and materials for the wireless arrangement. Wireless networks are also more efficient than their wired peers in regards to auxiliary measurements, involving measurement of substances at several points. Adding robustness to wireless, self-organizing networks is easy, because when new wireless components are introduced to a network, they can link to the existing network without needing to be reconfigured manually. Gateways can accommodate a large number of devices, allowing a very elastic range for expansion.

In a coal fired plant, plant operators walk a tightrope in monitoring multiple elements of the process. They calibrate limestone feed rates in conjunction with desulfurization systems, using target values determined experientially. A difficult process environment results from elevated slurry temperature, and the associated pH sensors can only last for a limited time under such conditions. Thanks to the expandability of wireless transmitters, the incremental cost is reduced thanks to the flexibility of installing new measurement loops. In regards to maintenance, the status of wireless devices is consistently transmitted alongside the process variable. Fewer manual checks are needed, and preventative measures may be reduced compared to wired networks.

Time Synchronized Mesh Protocol (TSMP) ensures correct timing for individual transmissions, which lets every transmitter’s radio and processor ‘rest’ between either sending or receiving a transmission. To compensate for the lack of a physical wire, in terms of security, wireless networks are equipped with a combination of authentication, encryption, verification, and key management. The amalgamation of these security practices delivers wireless network security equal to that of a wired system. The multilayered approach, anchored by gateway key-management, presents a defense sequence. Thanks to the advancements in modern field networking technology, interference due to noise from other networks has been minimized to the point of being a rare concern. Even with the rarity, fail-safes are included in WirelessHARTTM.

All security functions are handled by the network autonomously, meaning manual configuration is unnecessary. In addition to process control environments, power plants will typically use two simultaneous wireless networks. Transmitters allow both safety showers and eyewash stations to trigger an alarm at the point of control when activated. Thanks to reduced cost, and their ease of applicability in environments challenging to wired systems, along with their developed performance and security, wireless industrial connectivity will continue to expand.

Share your process measurement and control challenges with knowledgeable professionals, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Trace Moisture Analyzer

Portable and fixed installation trace moisture analyzers
Courtesy Teledyne Analytical Instruments

Moisture, the presence of water molecules, can impact certain products and processes in undesirable ways. Trace moisture analysis of clean gases can be accomplished using aluminum oxide sensors, one of several technologies available.

Instruments are available for continuous monitoring of moisture levels, or spot checking. Aluminum oxide moisture sensors rely on the change in capacitance within the sensor, which varies with the moisture content.

A concern with aluminum oxide sensor technology is drift associated with temperature and aging. A great degree of this has been alleviated through changes in sensor structure. The technology and instrumentation is easily applied and requires little in the way of maintenance other then periodic calibration.

More detail and explanation of the technology and instruments can be found in the brochure included below. Share your process analytical measurement challenges with experienced product specialists, combining your own process knowledge and experience with their up to date product expertise to develop effective solutions.

Trace Moisture Analyzer For Industrial Use from Miller Energy, Inc.