Monday, October 17, 2016

Applying Process Refractometers in Sugar Cane Processing

Sugar cane and refined white sugar
Refractometers measure concentration of dissolved solids
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.

(This is a repost of a blog originally appearing on the Electron Machine Corp. blog, 08/2016)

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 refractometry challenges and applications with the product application specialists for access to the best product selection resources.

Wednesday, October 12, 2016

Conductivity Controller For Boiler Applications

Multivariable water quality controller
Conductivity controller for boiler applications
Lakewood Instruments
Modern boilers using the Rankine cycle require feedwater and make-up feedwater quality maintained within certain limits with respect to alkalinity, conductivity, and other factors in order to maintain boiler operating efficiency and minimize maintenance requirements.

Controlling the feedwater quality can be accomplished with the addition of controlled amounts of the right chemicals to regulate various aspects of water quality. Another method is to purge, or blowdown, the boiler in a measured fashion that allows fresh feedwater to replace overly contaminated water. Filtration, which I generally deem to include ion exchange, reverse osmosis, and mechanical filtration, is a third method. All deal specifically with a limited scope of contaminates that have an impact on boiler operation and longevity.

Boiler blowdown can be used to limit the amount of total dissolved solids in the boiler drum water. As water boils, the dissolved solids in the water concentrate in the remaining liquid water. Blowdown purges a portion (or all) of this water, allowing the addition of water, presumably treated, with substantially lower total dissolved solids.

Boiler blowdown has an energy cost, since the replacement water must be heated to the design condition. It follows that executing this procedure should be undertaken when necessary, but not more frequently. A conductivity monitor and controller can accomplish properly timed blowdown cycles. The system consists of a conductivity sensor and a control unit that provides all the necessary functionality in a single integrated package. A data sheet is included below for one such unit from Lakewood Instruments.

Share your boiler operation challenges with an instrumentation specialist an explore how a properly instrumented steam system can provide operational savings and extended time between failure.

Thursday, October 6, 2016

Process Control - Annunciator Panel as Cyber Defense Measure

Process control annunciator panel
Standalone Annunciator Panel
Ronan Engineering Company
There are numerous applications for annunciator panels, stations, and equipment throughout the various industrial markets. One such application, arising and growing with the connectivity of industrial control systems to the internet, is in the cyber defense arena.

Industrial control systems are increasingly internet connected, making them vulnerable to cyber attack. There was a time when all that was necessary for plant or operation security was installing a perimeter fence around the property and posting a guard at the gate. Our industrial control systems are now subject to mischief or malicious attack from locations and parties unknowable and worldwide.

Do you know of ICS-CERT? If involved in industrial control, you should. It is the Industrial Control Systems Cyber Emergency Response Team, a part of the Department of Homeland Security that provides operational capabilities to defend control systems against cyber threats. You can follow them on Twitter, @ICS-CERT, and monitor the vulnerabilities and threats that they discover in the industrial control sphere. New items are added almost daily, naming specific vulnerabilities uncovered in named systems and equipment. Chances are that you will discover some of the equipment in your plant listed.

Annunicator systems and equipment can be employed as an isolated "watcher", monitoring process performance and providing alerts when conditions exceed specified limits.
A major impact of a potential cyber attack scenario is that, as operator, you can no longer fully trust what your software based internet connected control system is telling you, or whether it is doing everything it should and only those things that it should. An annunciator system, isolated from the primary control system and the internet, monitoring critical process conditions, incorporates a substantial level of safety against cyber attack.

There is more to be learned. Browse the document included below for a detailed visual demonstrating the set up of annunciators that can be isolated from your network. Share your process control challenges with specialists, and combine your process and facility knowledge with their product application expertise to develop effective solutions. And start following @ICS-CERT on Twitter and build your awareness and knowledge of industrial control cyber threats. 

Thursday, September 29, 2016

Silicone Rubber Heater Blankets - Flexible Heat Where You Need It

silicone rubber flexible heating blanket
Silicone rubber heater in one
of its simplest forms
Electric heaters for industrial and commercial applications are available in an almost dizzying range of types, materials, and forms. One of those is the silicone rubber heater.

Stock shapes and sizes are available from many manufacturers, but one distinct advantage of silicone rubber heaters is their flexibility. The resistance heater wires are encased in a silicone rubber sheet, providing the ability to wrap the assembly around an object or manipulate it into a close fit with the target of a heating application. The silicone rubber encasement also provides a high level of protection for the heater wires from impact, moisture, and some chemicals.

The watt density of the heaters can be specified to provide a good match between the delivery of heat and the need for it. Custom shapes and configurations can be manufactured to order, and on board or remote controllers provided. Pressure sensitive adhesive is a common option that facilitates the installation of the heater assembly to a part or vessel.

The maximum application temperature is in the range of +450°F (+232°). These heaters are a useful selection option for a large range of operations demanding heat to be applied directly to a surface, object, tank, drum, or other vessel. Share your industrial heating requirements with product specialists for the best match up between heater technology and your application.

Tuesday, September 20, 2016

Applying Precision Turbine Flow Meters

turbine flow meters flanged and threaded
High precision turbine flow meters
Courtesy Cameron Measurement Systems
Precision turbine flow meters are specially designed to accommodate a broad range of precise fluid measurement applications. They accommodate greater flow rates with lower pressure drops than other meters in their class. Some have a self-flushing design for longer sustained accuracy. The turbine's high-frequency digital output is suitable for interfacing with an assortment of readout and recording equipment. Some turbine flow meters have a symmetrical bi-directional design that supports reverse flow applications without a reduction in accuracy or capacity.

Operating Principle

(The following is excerpted from Model 700 Series Turbine Flowmeter User Manual, from Cameron Measurement Systems....with some editing)

Fluid flows over a diffuser section and is accelerated onto a multi-blade hydro-dynamically balanced turbine rotor. The rotor speed is proportional to the volumetric flow rate. As the rotor turns, a reluctance type pickup coil (mounted on the meter) senses the passage of each blade tip and generates a sine wave output with a frequency that is directly proportional to the flow rate.

The rotor is the only moving part of the turbine flow meter. The small lightweight rotor hubs ensure fast response to process flow changes. The rotor is hydro-dynamically balanced during operation, eliminating the need for mechanical thrust leveling. This low-friction design improves metering linearity and reduces wear and maintenance.

A variable reluctance generating pickup coil contains a permanent magnet and a wire winding. In some cases, the rotor blade of the turbine meter is made of a ferritic stainless steel such as grade 430. The movement of the rotor blade in proximity to the magnetic field of the coil tip produces an AC type voltage pulse within the coil winding. An alternate arrangement finds the ferritic bars embedded in the rotor shroud, where they can interact with the pickup coil. Increasing the quantity of bars on the shroud to outnumber the rotor blades provides more pulses per unit volume (resolution). This feature can be valuable when proving large-capacity meters with a small-volume prover. Shielded wire cable conveys the output of the pickup coil to compatible electronic instruments to indicate flow rate, record, and/or totalize the volumetric flow. The coil itself does not require electrical power to operate.

The meter may be factory-fitted with multiple coils for redundancy, indication of flow direction or pulse train verification. The pickup coil type and magnetic strength vary with application requirements.

The turbine flow meters are calibrated in a horizontal position. Therefore, the best correlation of calibration occurs when the meter is operated in this plane. However, the meter will operate satisfactorily in any position.

System Pressure

The maximum and minimum system pressures must be considered when applying the turbine meter. To obtain proper response, a back pressure should be applied to the meter. This back pressure should be at least twice the pressure drop of the meter at maximum flow. For liquid meters, the back pressure should be twice the pressure drop of the meter at maximum flow, plus twice the fluid vapor pressure.


Turbine flow meters, with their simple, durable construction and wide operating range, may be the right choice for a number of applications. As with all instrumentation, there are a number of factors to consider when making a selection. Share your flow measurement challenges and requirements with instrumentation specialists, combining your process knowledge with their product application expertise to develop the most effective solutions.

Thursday, September 15, 2016

Video Demonstration of Transit Time Difference Method of Flow Measurement

portable ultrasonic flow meter Flexim
Portable Ultrasonic Flow Meter
The measure of flow is a pervasive task in fluid process control. There are several differing technologies employed for measuring fluid flow, each with its own set of performance and application attributes that might make it the advantageous choice for a particular operation.

Ultrasonic flow measurement uses several methods for determining the average velocity of a fluid. One of those methods employs the difference in the transit times of ultrasonic pulses travelling with the flow direction and against the flow direction. The flow velocity of the media will offset the transit times between the flow and counterflow measurements. The measured difference in transit times can be used to determine average flow velocity and, with additional processing, mass flow.

Ultrasonic flow meters are accurate and provide repeatable results, making them suitable for custody transfer operations, as well as many other process control applications. Little maintenance is required and the units have no moving parts. Measurement instruments are available with in-line or clamp-on mounting, providing a high level of installation and application flexibility.

The short video below provides a clear explanation of how transit time difference measurement works. Share your flow measurement challenges and requirements with a product application expert, combining your process knowledge with their product expertise to develop effective solutions.

Wednesday, September 7, 2016

RTD or Thermocouple for Your Temperature Measurement Application?

RTD or thermocouple temperature sensor assembly
Temperature Sensor Assembly
Proper temperature sensor selection is key to getting useful and accurate data for maintaining control of a process. There are two main types of temperature sensors employed for industrial applications, thermocouple and resistance temperature detector (RTD). Each has its own set of features that might make it an advantageous choice for a particular application.

Thermocouples consist of a junction formed with dissimilar conductors. The contact point of the conductors generates a small voltage that is related to the temperature of the junction. There are a number of metals used for the conductors, with different combinations used to produce an array of temperature ranges and accuracy. A defining characteristic of thermocouples is the need to use extension wire of the same type as the junction wires, in order to assure proper function and accuracy.
Here are some generalized thermocouple characteristics.

  • Various conductor combinations can provide a wide range of operable temperatures (-200°C to +2300°C).
  • Sensor accuracy can deteriorate over time.
  • Sensors are comparatively less expensive than RTD.
  • Stability of sensor output is not as good as RTD.
  • Sensor response is fast due to low mass.
  • Assemblies are generally rugged and not prone to damage from vibration and moderate mechanical shock.
  • Sensor tip is the measuring point.
  • Reference junction is required for correct measurement.
  • No external power is required.
  • Matching extension wire is needed.
  • Sensor design allows for small diameter assemblies.
RTD sensors are comprised of very fine wire from a range of specialty types, coiled within a protective probe. Temperature measurement is accomplished by measuring the resistance in the coil. The resistance will correspond to a known temperature. Some generalized RTD attributes:
  • Sensor provides good measurement accuracy, superior to thermocouple.
  • Operating temperature range (-200° to +850°C) is less than that of thermocouple.
  • Sensor exhibits long term stability.
  • Response to process change can be slow.
  • Excitation current source is required for operation.
  • Copper extension wire can be used to connect sensor to instruments.
  • Sensors can exhibit a degree of self-heating error.
  • Resistance coil makes assemblies less rugged than thermocouples.
  • Cost is comparatively higher
Each industrial process control application will present its own set of challenges regarding vibration, temperature range, required response time, accuracy, and more. Share your process temperature measurement requirements and challenges with a process control instrumentation specialist, combining your process knowledge with their product application expertise to develop the most effective solution.