Water Quality Analysis – Constituent Survey (Part 1)

Wastewater Treatment Plant

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. Share your water analysis and treatment challenges with application experts, combining your own process expertise with their product knowledge to develop effective solutions.

Next Generation of Medium Voltage Drives From Siemens

One of several variants of the GH180
medium voltage drive
Courtesy Siemens

Siemens, global leader in drive technology, has released its latest generation of medium voltage drives. The Sinamics GH180 line incorporates a newly designed power cell with a reduced part count that increases unit reliability and reduces space requirements. The new drive delivers a number of advantages and improvements.

• High reliability with fault tolerance through cell redundancy and Siemens Advanced Cell Bypass
• Energy efficiency through improved unit control for better throughput and less energy waste
• Delivers near unity power factor by eliminating harmonic current and voltage distortion
• Reduced motor insulation stress and harmonic heating
• Significant torque pulsations eliminated from load
• Proactively alerts operator of potential issues before they become shutdown worthy problems

The drives are suitable for new and retrofit installations because of their compact size. A range of models cover applications from 300 kVA through 18,000 kVA.

A datasheet is included below that provides more detail. Share your motor drive challenges and applications with a product specialist and combine your process and facility knowledge with their product application expertise to develop effective solutions.

Next Generation Medium Voltage Drives from Instrument Specialties, Inc.

High Performance Butterfly Valves

Valdisk High Performance Double Offset Butterfly Valve
Courtesy Flowserve - Valtek

Industrial process control applications can present stringent and challenging performance requirements for the physical equipment and components that comprise the process chain. The valves employed in fluid based operations need to be resistant to the impact of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are maintained in a predictable way.

Industrial valves intended for extreme applications are generally referred to as severe service or high performance valves. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define what constitutes a severe service valve.

So, how do you know when to focus valve selection activities on severe service or high performance valves, as opposed to those rated for general purpose? There are a number of basic criteria that might point you in that direction:

• Extreme media or environmental temperature or pressure
• High pressure drop operation that may cause cavitation
• Rapid or extreme changes to inlet pressure
• Certain types or amounts of solids contained in the fluid
• Corrosive media

Certainly, any of these criteria might be found in an application serviceable by a general purpose valve, but their presence should be an indicator that a closer assessment of the fluid conditions and commensurate valve requirements is in order. The key element for a process stakeholder is to recognize when conditions are contemplated that can exceed the capabilities of a general purpose valve, leading to premature failure in control performance or catastrophic failure that produces an unsafe condition. Once the possibility of an extreme or challenging condition is identified, a careful analysis of the range of operating conditions will reveal the valve performance requirements.

There are numerous manufacturers of severe service or high performance valves, each with specialized product offerings focusing on a particular performance niche. Flowserve, under their Valtek brand, manufactures the Valdisk high performance butterfly valves ranging from NPS 2-52 and ASME class 150, 300, 600, 900, 1500 pressure ranges. The valve design is ideal for manual or automated actuation, installed with a manual hand gear, electric actuator, or a pneumatic actuator. Seats are available as soft or metal on this double offset butterfly valve that provides tight closure for bi-directional flow. Construction materials include carbon steel and stainless steel. A range of options and variants are available to customize the valve build to suit a replacement or new installation.

There is more information available about the Valtek high performance offering. You can always get more information and discuss your special requirements with a valve specialist. They have application experience and access to technical resources that can help with selecting the right valve components to meet your severe service and high performance applications.

Proper Installation of Rupture Disc Assures Proper Performance - Here's How

Rupture discs are fixed setpoint devices designed to provide failsafe performance in venting gases or liquids in the case of excessive pressure. The precision made and certified disc is contained within a holder specially designed for the disc and to facilitate proper inspection and maintenance.

Fike is a globally recognized manufacturer of products that protect people and critical assets from dangers such as fire, explosion and over-pressurization. With over 60 years experience manufacturing products ranging from rupture discs and explosion protection systems, to fire suppression and fire alarm systems, Fike offers reliable solutions for customers around the world.

An integral part of the inclusion of a safety device in a process system is the manner in which it is installed. Documented product performance, upon which the user is depending, is predicated upon installation in a manner which duplicates the rating condition. Varying from the manufacturer's installation procedure or instructions can have an impact on the performance of almost any process measurement and control product, but adherence to procedure is especially important when safety devices are concerned. The video below demonstrates the proper procedure for installing Fike rupture discs.

Fike provides certified rupture discs to meet all applications for process industries including isolating pressure relief valves from corrosive materials, reducing involuntary emissions, insuring pressure relief in critical applications, rupture discs for sanitary/pharmaceutical processes.

Share your over-pressure safety requirements with a product specialist and select from the complete line of cost-effective rupture discs, holders and custom pressure relief devices which are compliant with global code regulations and designed to meet or exceed industry requirements for performance, reliability and quality.

Protecting Pressure Relief Valves and Safety Relief Valves

A rupture disc can provide PRV isolation

Safety and pressure relief valves are common elements of any pressurized system. Their general purpose is to stop system pressure from exceeding a preset value, preventing uncontrolled events that could result in damage to personnel, environment, or assets. Their operating principle and construction are comparatively simple and well understood.

Long term exposure of a relief valve to any number of media can result in corrosion, material buildup, or other conditions which may shorten the useful life of the valve, or worse, impair its proper operation. This excessive wear will increase the ongoing cost of maintaining or replacing a prematurely worn valve. One other aspect of relief valves can be the reduction in their seal integrity or force as the system pressure approaches the setpoint. This could possibly lead to fugitive emissions, an undesirable condition.

A reasonable solution is posed by Fike, globally recognized leader in fire, explosion, and overpressure protection. Isolating a relief or safety valve from the process media through the installation of a rupture disc upstream of the valve inlet will eliminate exposure of the costly valve to effects of the media. It is necessary to establish proper rating and selection for the rupture disc to avoid any impairment of the overall operation of the relief valve, but the selection criteria are not complex. A number of benefits can accrue with this concept.

• Avoid purchase of relief valves manufactured from exotic materials to accommodate exposure to corrosive media. Rupture disc provides isolation of the valve from the media.
• Eliminate fugitive emissions at the relief valve. Rupture discs, when properly installed, are leak free and bubble tight.
• Relief valve inventory can be evaluated for reduction.
• Longer valve life.
• Less downtime.

The additional cost for the rupture disc enhancement can have a reasonable payback period, with all factors considered. In any case, the rupture disc protection makes for a cleaner relief valve installation.

Rupture discs and holders are available in sizes and materials for most applications. Share your ideas with a product specialist, combining your process knowledge with their product application expertise to develop an effective solution.

Applying rupture discs for relief valve protection from Instrument Specialties, Inc.

Refractometry in Industry

In-line Process Refractometer
Courtesy K-Patents

Refractometry, a combination of physics, materials, and chemistry, is the process which measures the composition of known substances by means of calculating their respective refractive indexes (RI). RIs are evaluated via a refractometer, a device which measures the curve, or refraction, resulting when the wavelength of light moves from the air into and through a tested substance. The unitless number given by the refractometer, usually between 1.3000 and 1.7000, is the RI. The composition of substances is then determined when the RI is compared to a standard curve specific to the material of the substance. There are also four separate types of refractometers: digital, analog, lab, and inline process. Although refractometry can measure a variety of substances, including gases and solids, the most common category of known substances to calculate are liquids; the inline process refractometer is used to quantify the makeup of liquids.

The ultimate focus of industrial refractometry is to describe what is in a final product or output of a process step. A field which relies directly on the results of refractometry is gemology. Gemological refractometry is crucial for accurately identifying the gemstones being classified, whether the gemstones are opaque, transparent, or translucent.

Other common examples of industrial refractometry uses are measuring the salinity of water to determine drinkability; figuring beverages’ ratios of sugar content versus other sweeteners or water; setting eye-glass prescriptions; understanding the hydrocarbon content of motor fuels; totaling plasma protein in blood samples; and quantifying the concentration of maple syrup. Regarding fuels, refractometry scrutinizes the possible output of energy and conductivity, and for drug-testing purposes, refractometry measures the specific gravity, or the density, of human urine. Regarding food, refractometry has the ability to measure the glucose in fruit during the fermentation process. Because of this, those in food services know when fruit is at peak ripeness and, in turn, also understand the most advantageous point in the fruit’s “lifetime” to put it on the market.

The determination of the substance composition of the product examples listed above all speak to the purpose of quality control and the upholding of standardized guidelines; consumers rely on manufacturers not only to produce these products but also to produce these products consistently and identically every single time. Therefore, the success of commercialism, etc. is dependent on maintaining the standards for the composition of substances, i.e. industrial refractometry.

Equipment manufacturers have developed numerous refractometer configurations tailored to specific use and application. Each has a set of features making it the advantageous choice for its intended application. Product specialists can be invaluable sources of information and assistance to potential refractometer users seeking to match the best equipment to their application or process.

Process Refractometer For Concentration Measurement of Liquids from Instrument Specialties, Inc.

Summary of Technologies Used For Continuous Liquid Level Measurement in Industrial Process Control

Two versions of radar level transmitters
Courtesy Krohne

Automated liquid processing operations in many fields have requirements for accurate and reliable level measurement. The variety of media and application criteria demand continuous improvement in the technology, while still retaining niches for older style units utilizing methods that, through their years of reliable service, inspire confidence in operators.

Here is a synopsis of the available technologies for instruments providing continuous liquid level measurement. All are generally available in the form of transmitters with 4-20 mA output signals, and most are provided with additional outputs and communications. What is notably not covered here are level switches or level gauges that do not deliver a continuous output signal corresponding to liquid level.

Whether considering a new installation or upgrading an existing one, it can be a good exercise to review several technologies as possible candidates for a project. None of the technologies would likely be considered the best choice for all applications. Evaluating and selecting the best fit for a project can be facilitated by reaching out to a product application specialist, sharing your applications challenges and combining your process knowledge with their product expertise to develop an effective solution.

Displacer – A displacer is essentially a float and a spring that are characterized for a particular liquid and range of surface level movement. The displacer moves in response to liquid level, changing the location of a core connected to the displacer by a stem. The core is within a linear variable differential transformer. The electrical output of the transformer changes as the core moves.

Guided Wave Radar – A radar based technology that uses a waveguide extending into the liquid. The radar signal travels through the waveguide, basically a tube. The liquid surface level creates a dielectric condition that generates a reflection. Calculations and processing of the emitted and returned signals provide a measure of distance to the liquid surface. No moving parts.

Magnetostrictive – A method employing measurement of the transit time of an electric pulse along a wire extending down an enclosed tube oriented vertically in the media. A magnetic float on the exterior of the tube moves with the liquid surface. The float’s magnetic field produces the return signal to the sensor. Processing the time from emission to return provides a measure of distance to the liquid surface.

Pulse Burst Radar - A radar based technology employing emissions in precisely timed bursts. The emission is reflectex from the liquid surface and transit time from emission to return is used to determine distance to media surface.  Not adversely impacted by changes in media conductivity, density, pressure, temperature. No moving parts.

Frequency Modulated Continuous Wave Radar – Another radar based technology that employs a radar signal that sweeps linearly across a range of frequencies. Signal processing determines distance to media surface.  Not adversely impacted by changes in media conductivity, density, pressure, temperature. No moving parts.

RF Capacitance - As media rises and falls in the tank, the amount of capacitance developed between the sensing probe and the ground reference (usually the side metal sidewall) also rises and falls. This change in capacitance is converted into a proportional 4-20 mA output signal. Requires contact between the media and the sensor, as well as a good ground reference. No moving parts.

Ultrasonic Non-Contact – Ultrasonic emission from above the liquid is reflected off the surface. The transit time between emission and return are used to calculate the distance to the liquid surface. No contact with media and no moving parts.

Differential Pressure – Pressure sensor at the bottom of a vessel measures the pressure developed by the height of the liquid in the tank. No moving parts. A variation of this method is often called a bubbler, which essentially measures hydrostatic pressure exerted on  the gas in a tube extending into the contained liquid. It has the advantage of avoiding contact between the measuring instrument parts, with the exception of the dip tube, and the subject liquid.

Laser - Probably one of the latest arrivals on the liquid level measurement scene, laser emission and return detection is used with time interval measuring to accurately determine the distance from the sensor source to the liquid surface.

Load Cell - A load cell or strain gauge can be incorporated into the support structure of the liquid containing vessel. Changes in the liquid level in the vessel are detected as distortions to the structure and converted, using tank geometry and specific gravity of the liquid.

All of these technologies have their own set of attributes which may make them more suitable to a particular range of applications. Consulting with a product specialist will help determine which technologies are the best fit for your application.