Saturday, December 16, 2017

Increasing Safety in Chemical Waste Water Treatment Plant

Waste water treatment and location of the measurement
Waste water treatment and location of the measurement.
Purified Terephthalic Acid (PTA) is the preferred raw material for the most common plastic products of daily life. The PTA production process generates various waste water streams which are high in organic content.

Purification of Process Waste Water

In the waste water treatment plant, the water treatment starts with aeration. The last step is an anaerobic bio reactor where the treatment is done in a controlled atmosphere. Micro organisms purify the water and produce biogas. Biogas roughly consists of 60 % methane and 40 % Carbon dioxide. This biogas is compressed and used as a fuel to reduce the net energy supply.

Although production or intrusion of oxygen into the reactors or pipes is highly unlikely, safety systems are installed. In case air enters unexpectedly into the process this first may result in a non-supporting atmosphere for the microbes and in the worst case the gas mixture may lead to an explosion.

Safety Guaranteed Using Siemens LDS 6

To ensure that oxygen never exceeds the maximum accepted concentration, the customer chose an in-situ measurement with the Siemens Laser Diode Spectrometer LDS 6. LDS 6 performs a continuous monitoring of the oxygen concentration in the biogas produced.
Measurement path and the two LDS 6 sensor heads
Measurement path and the
two LDS 6 sensor heads.

The response of the system is in three levels:
  1. In case the oxygen level exceeds 5 % an alarm is triggered.
  2. The threshold of 7 % causes an automatic nitrogen injection and the closure of a valve preventing the gas mixture from entering into the compressor.
  3. When the limit of 9 % is exceeded, this automatically shuts down the compressor.
The in-situ measurement leads to a fast and reliable measurement.

The stability and availability of the LDS 6 system is ensured by the integrated reference cell which provides a lifetime calibration. To be absolutely on the safe side, the customer operates a weekly safety check which involves opening a valve that allows a controlled air intake into the LDS 6 sensor heads. As the sensor heads are physically separated from the process by process windows, no oxygen may enter into the process. The reaction of the system shows in any of these tests once more the reliability of the measurement method used.

For more information about this application, or for any analytical instrument requirement, contact Ives Equipment by calling (877) 768-1600 or visiting https://www.ivesequipment.com.

Reprinted with permission from Siemens Case Study.

Thursday, November 30, 2017

Beverage Container Manufacturer Improves Production Inventory Control with Radar Level Transmitter

SITRANS LR560 Radar Level Transmitter
SITRANS LR560 Radar Level Transmitter
A company in the southeastern United States produces and supplies beverage containers to a large number of bottling plants. The company produces a wide size range of polyethylene terephthalate (PET) bottles for both carbonated soft drinks and water. PET bottles are formed in a two-step process that includes both injection-molding and blow-molding equipment.

Challenge

The customer has a need to monitor the level in storage tanks containing crystallized PET plastic pellets used in the production of plastic soft drink bottles. The crystallized pellets range in density from 30 pounds per cubic feet to 56 pounds per cubic feet, and the tanks can be up to 60 feet in height.

The level measurement is used for inventory control, and it is important to maintain material supply during production periods. Production needs to know if they will need to switch tanks if the inventory is running low.

The customer had been using a plumb-bob for the level measurements and had also tried ultrasonic level measurement instruments, from a different vendor, in the past. The plumb bob cable became a mechanical nuisance, and because of high dust levels, the customer had experienced periodic loss of echo using the ultrasonic level devices.

Solution

The local Siemens representative convinced the customer to install a trial unit of the SITRANS LR560 radar level transmitter. The LR560 transmitter provided a continuous, repeatable and low-maintenance level measurement solution. The SITRANS LR560 unit’s plug and play performance is ideal for most solids level measuring applications, including those with extreme dust and high temperatures.

Its unique design allows safe and simple programming using the intrinsically-safe handheld programmer without having to open the instrument’s lid.

Results

The customer tested the trial unit for almost a year, and because of their confidence in the reliability of the level measurements, the customer placed an order for an additional 9 instruments for use in their storage silos.

Benefits

Time savings: No maintenance required. Because the SITRANS LR560 radar transmitter is a non-contacting instrument, the risk of product contamination is eliminated and no extended delays are caused as when plumb-bob cables get caught or broken.

Improved process reliability: Continuous level measurement is a real time indicator of how much is in the silo. A plumb-bob cable getting stuck at a certain distance can lead to misinterpretation of the actual level. After the cable gets stuck, there is no level history prior to the last request on demand from the instrument.

Easier to use: The SITRANS LR560 transmitter was set up using the quick start wizard and no further tuning or maintenance is required.

Unique product features: The local user interface allows for ease of con-figuration and set-up. Since the customer is only using the removable, local display during setup, the custom-er can save money by moving the display from unit to unit as needed. The narrow, 4-degree beam angle enables reliable depth penetration into the silo and ignores potential silo wall interference.

About the SITRANS LR560 Radar Level Transmitter The SITRANS LR560 2-wire, 78 GHz FMCW radar level transmitter is used for continuous monitoring of solids in silos to a range of 100 meters or 328 feet. Its plug and play performance is ideal for most solids applications, including those with extreme dust and high temperatures to +392ºF. Its unique design provides safe and simple programming using the intrinsically-safe handheld programmer without having to open the instru-ment’s lid.

The SITRANS LR560 transmitter includes an optional graphical local display interface (LDI) that improves setup and operation using an intuitive Quick Start Wizard, and echo profile display for diagnostic support. Startup is easy using the Quick Start wizard with a few parameters required for basic operation. The SITRANS LR560 instrument measures virtually any solids material level up to a range of 328 feet.

To discuss this, or any process instrument application, contact Ives Equipment by calling (877) 768-1600 or visit https://www.ivesequipment.com.

Tuesday, November 28, 2017

Vector System Image Processor for Water in Hydrocarbons and Particles in Hydrocarbons

Canty Process Technology specializes in many refinery applications. Some applications include oil in water / water in oil, hydrogen reformer cameras, and desalter monitors. The CANTY Inflow™ is a vision-based camera system used with the CANTY Vector System image processor for water in hydrocarbons and particles in hydrocarbons in a lab environment / at-line / in-line process. The presence of these two physical contaminants is a problem for equipment the hydrocarbon is entering.

The CantyVision™ Software accurately measures multiple aspects of the hydrocarbons from water / solids / gas independent of each other for accurate data. In comparison to a laser and capacitance, which measures only one dimension and can’t identify the difference of water and solids in the stream. The CantyVision™ software can identify the differences. The customer can also visually verify the readings. 

Hydrocarbon contamination takes place mainly in production and transportation. CANTY objectively takes the measurement and reports based on a two dimensional image. Solids & water are all measured and continuously and objectively monitored. By knowing whether there is a water or solids problem this helps the operators identify how to fix the problem. The Inflow™ is an in-line analysis system to make sure production samples are not skipped over.

A brochure for the Canty Inflow™ can be downloaded here.

Saturday, November 11, 2017

Introduction to the SIEMENS SIPART PS2 Smart Valve Positioner

The Siemens SIPART PS2 is currently the most widely used positioner for linear and part-turn actuators in a broad range of process industries. The proven all-rounder offers comprehensive functionality and diagnostics, controls a variety of valves both safely and reliably, and fulfills a multitude of highly specific requirements.

For more information, visit http://www.ivesequipment.com or call 877-768-1600.

Wednesday, October 25, 2017

United Electric Controls Product Catalog

UE Champion Distributor
Ives Equipment is a
UE Champion Distributor
United Electric Controls has a rich history of over 80 years in providing protection for plant assets, people and the environment. Their pressure and temperature instrumentation is designed specifically to meet the rigors of harsh and hazardous alarm and emergency shutdown applications and includes certified safety transmitters per IEC 61508. UE, and Ives Equipment, serves the Chemical & Petrochemical, Power, Water & Wastewater and Oil & Gas industries, as well as many other challenging OEM applications.

You can download a PDF of the UE product catalog here, or view it online below.

Tuesday, October 24, 2017

Tried and True: Industrial Bulb and Capillary Temperature Switches

UE NEMA 4 Temperature Switch
UE watertight and corrosion resistant temperature switch.
Not all processes or operations require the use of state of the art technology to get the desired result. Part of good process design is matching up the most appropriate methods and technology to the operation.

One method of changing the state of an electrical switch from open to closed in response to a process temperature change is a bulb and capillary temperature switch.  The change in state occurs in the mechanical switch when the temperature of a process control operation crosses a certain threshold. Bulb and capillary switches have the advantage of operating without requiring an excitation voltage, simplifying their use in a given application.

The physical operating principle behind the capillary thermostat relies on the use of a fluid. The fluid inside the thermostat expands or contracts in response to the temperature at the sensing bulb. The change in fluid volume produces a force upon a diaphragm or other mechanical transfer device. The diaphragm is connected to, and changes the status of, an adjoining circuit using a snap action switch.

Because of their simplicity and comparatively modest cost, commercial versions of bulb and capillary switches find application throughout residential and commercial settings. Some common applications include warming ovens, deep fat fryers, and water heaters.

UE hazardous area temperature switch
UE hazardous area temperature switch.

Industrial versions of bulb and capillary switches are fitted with appropriate housings for the installation environment. Housings designed for hazardous areas, drenching or submersion, high dust or high corrosive environments are standardly available. Many switching options exist as well, such as high current ratings, SPDT, DPDT, dual SPDT, adjustable deadbands, and internal or external adjustments.

Operation of the temperature switches is subject to a few limitations. The setpoint is most often fixed, so changing the setpoint accurately requires trial and error or a calibration procedure. The temperature range over which the switches are suitable is comparatively limited, with a matching of the bulb and capillary fluid system to the application temperature range a necessary task in product selection. Within its proper sphere of use, though, bulb and capillary temperature switches offer simple, reliable operation, with little requirement for maintenance.

Time-tested, and application proven, these simple mechanical devices are still strong candidates for applications in any temperature control process. As with any process instrument implementation, we strongly suggest you share your application requirements with a knowledgable product specialists for the best solution.

Monday, October 23, 2017

Siemens Ultrasonic Level - How it Works

Ultrasonic level measurement
Ultrasonic level measurement is a highly cost-effective solution for short- and long-range measurement, even under difficult environmental conditions such as vibrations and dust. Ultrasonic level measurement is a non-contacting technology used in numerous industrial areas to monitor and control the level of liquids, slurries and solids.

Watch the video below for a better understanding of how this technology works.



For more information on Siemens ultrasonic level measurement, contact Ives Equipment by calling (877) 768-1600 or visiting http://www.ivesequipment.com.

Friday, October 20, 2017

The Role of a Sensor, Logic Solver and Final Element in a SIS (Safety Instrumented System)

One Series safety Transmitter
UE One Series Safety Transmitter
IEC 61511 is a technical standard which establishes practices that ensure the safety of industrial processes through the use of instrumentation. Such systems are referred to as Safety Instrumented Systems. The title of IEC 61511 is "Functional safety - Safety instrumented systems for the process industry sector".

Traditional safety systems that follow the IEC 61511 standard consists of three major components: a sensor, or a transmitter; a logic solver, or a safety PLC; and the final element, which is often a pilot valve.

Many major manufacturers provide process transmitters with safety integrity level third-party certifications to provide the industry standard for 4-20 milliamp output. This analog signal retransmits the process variable to the safety PLC for analysis where algorithms test to see if the process is within safe operating parameters. If abnormal conditions are determined to exist, an alarm may be sounded and if dangerous conditions are confirmed, an emergency shutdown sequence may be initiated.

Further exploring the roles of each of these safety system components, all three must work together flawlessly in order to bring the plan to a safe state, or allow the process to continue and run in a safe manner. Reliability of each component becomes paramount to the proper operation of the safety instrumented function, or SIP, and therefore the safe operation in the plant.

For example, the central component must continuously monitor the process variable and provide this information to the safety PLC via a hardwired connection. What actually occurs however, is the analog signal from the sensor transducer is converted to the digital domain for processing. Digital signal processing occurs inside the transmitters electronics to adjust the signal for ambient and process temperature conditions, sensor response errors, signal filtering, user settings, sensor calibration, and the process variable display. The resulting conditioned and process signals converted back to the analog domain to retransmit the 4 to 20 milliamp signal over the hardwired connection to the safety PLC. The PLC must now determine if the analog signal reveals a dangerous condition by comparing the level of the analog signal with pre-programmed set points. Here is what actually occurs. The retransmitted analog 4-20 mA signal must be converted back to the digital domain for processing inside the safety PLC's electronics. The level of the signal is compared to a pre-programmed threshold that is set at the limit of safe operation. If the signal level is determined to be within the safe limits of operation, a relay inside the safety PLC will remain closed. If the signal level is determined to be outside in the safe operating limits of the process, the safety relay will open. The safety relay state - is it open or is it closed - will determine what action the final element will take via a hardwired connection.

The final element must now take action to perform the safety function. An example of a final element is a steam cut-off valve to a turbine generator. The valve, or the final element, can quickly close to cut off the steam that passes through the generator's rotor in order to stop the rotation. Here is what actually happens. A pilot valve is connected to the plant air supply. The pilot valve is actuated by energizing 120VAC solenoid coil. When the coil is energized, the valve is held open, allowing plant air to enter the pneumatic actuator for the steam valve. Air pressure is used to hold the steam valve open allowing steam to enter, and cause the turbine generator to rotate. If the signal from the safety PLC opens to de-energize the pilot valve coil, the pilot valve will close, cutting off the air supply to the steam valve, which will cause the steam valve to close. This is an example of a de-energized to trip (or DTT) safety function.

As you can see there are a lot of components that must operate as designed to shut down the turbine generator in the event that an abnormal condition exists. Examples of abnormal conditions may include low lubrication oil pressure, high lubrication oil temperature, steam pressure that's too high, inadequate plant air pressure, etc. In order to decrease the safety instrumented functions probability to fail on-demand, all of the functions described here must work flawlessly.

Saturday, September 30, 2017

Basics of Continuous Level Measurement

Continuous Level Measurement
Many industrial processes require the accurate measurement of fluid or solid (powder, granule, etc.) height within a vessel. Some process vessels hold a stratified combination of fluids, naturally separated into different layers by virtue of differing densities, where the height of the interface point between liquid layers is of interest.

A wide variety of technologies exist to measure the level of substances in a vessel, each exploiting a different principle of physics. This chapter explores the major level-measurement technologies in current use.

Level gauges (sightglasses)
Siteglass
Siteglass


Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found in industrial level-measurement applications, even when another level-measuring instrument is present, to serve as a direct indicator for an operator to monitor in case there is doubt about the accuracy of the other instrument.

Float

Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the surface of the fluid or solid within the storage vessel. The float itself must be of substantially lesser density than the substance of interest, and it must not corrode or otherwise react with the substance.

Hydrostatic pressure

A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on that fluid. The greater the vertical height of the fluid, the greater the pressure, all other factors being equal. This principle allows us to infer the level (height) of liquid in a vessel by pressure measurement.

Displacement

Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously measuring the weight of an object (called the displacer) immersed in the process liquid. As liquid level increases, the displacer experiences a greater buoyant force, making it appear lighter to the sensing instrument, which interprets the loss of weight as an increase in level and transmits a proportional output signal.

Echo

Echo level (radar)
Echo level (radar)
A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface of the liquid – typically from a location at the top of the vessel – using the time-of-flight for the waves as an indicator of distance, and therefore an indicator of liquid height inside the vessel. Echo-based level instruments enjoy the distinct advantage of immunity to changes in liquid density, a factor crucial to the accurate calibration of hydrostatic and displacement level instruments. In this regard, they are quite comparable with float-based level measurement systems. Liquid-liquid interfaces may also be measured with some types of echo-based level instruments, most commonly guided-wave radar. The single most important factor to the accuracy of any echo-based level instrument is the speed at which the wave travels en route to the liquid surface and back. This wave propagation speed is as fundamental to the accuracy of an echo instrument as liquid density is to the accuracy of a hydrostatic or displacer instrument.

Weight

Weight level
Weight level measurement
Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel. If the vessel’s empty weight (tare weight) is known, process weight becomes a simple calculation of total weight minus tare weight. Obviously, weight-based level sensors can measure both liquid and solid materials, and they have the benefit of providing inherently linear mass storage measurement. Load cells (strain gauges bonded to a steel element of precisely known modulus) are typically the primary sensing element of choice for detecting vessel weight. As the vessel’s weight changes, the load cells compress or relax on a microscopic scale, causing the strain gauges inside to change resistance. These small changes in electrical resistance become a direct indication of vessel weight.

Capacitive

Capacitive level
Capacitive level measurement
Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically
into a process vessel. As process level increases, capacitance increases between the rod and the vessel walls, causing the instrument to output a greater signal. Capacitive level probes come in two basic varieties: one for conductive liquids and one for non- conductive liquids. If the liquid in the vessel is conductive, it cannot be used as the dielectric (insulating) medium of a capacitor. Consequently, capacitive level probes designed for conductive liquids are coated with plastic or some other dielectric substance, so the metal probe forms one plate of the capacitor and the conductive liquid forms the other.

Radiation

Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by traveling through the bulk of material stored within those vessels. By placing a radioactive source on one side of the vessel and measuring the radiation reaching the other side of the vessel, an approximate indication of level within that vessel may be obtained. Other types of radiation are scattered by process material in vessels, which means the level of process material may be sensed by sending radiation into the vessel through one wall and measuring back-scattered radiation returning through the same wall.

To download an excellent continuous level selection guide follow this link.





Content above abstracted from “Lessons In Industrial Instrumentation”
by Tony R. Kupholdt under the terms and conditions of the
Creative Commons Attribution 4.0 International Public License.

Tuesday, September 12, 2017

Measuring H2S in CO2 Bottling Gas

OMA H2S Analyzer
OMA H2S Analyzer 
Reprinted with permission from Applied Analytics

Prior to filling, beer bottles are purged with CO2 to remove air and protect the taste against oxidation. In the fermentation process, yeast consumes sugar and expels a large amount of CO2 which can be "reclaimed" and used for this bottle purging purpose. Unfortunately, fermentation often also produces toxic, odorous sulfides which can foam up into the piping and contaminate the reclaimed CO2.

In order to continue using the great resource of CO2 byproduct yet avoid contaminating the bottled beer with foul-smelling toxins, the reclaimed gas is run through sulfide removal skids. However, sulfide breakthrough can occur if the gas does not spend enough time in the scrubber. Employees are sometimes tasked with sniff-testing the reclaimed CO2 , but this is an unhealthy practice and is too discrete to vigilantly prevent product contamination.

An automatic, continuous analysis solution is required in order to immediately divert contaminated CO2 from use in bottling as well as provide feedback control for the sulfur removal processing time.

The OMA H2S Analyzer is used to continuously measure concentrations of hydrogen sulfide (H2S) and dimethyl sulfide (DMS) in the fermentation byproduct gas. This system uses a full-spectrum UV-Vis spectrophotometer to detect the absorbance of sulfides in the reclaimed CO2 stream, an ideal method as CO2 has zero absorbance in the UV spectrum. The OMA provides fast response alarms to high-concentration threshold which allows immediate diversion of contaminated CO2.

For this application, the OMA is typically multiplexed to automatically cycle analysis between multiple sampling points. This maximizes system value by allowing one unit to monitor the raw fermentation gas entering the reclamation system, gas coming off the acid aldehyde scrubbers, and the bottling gas coming off of the sulfur removal beds -- all with sample stream switching at user-defined intervals.

Monday, September 11, 2017

Use of Process Analyzers in Fossil Fuel Plants

Steam Power Plant
Steam Power Plant
In spite of all efforts concerning energy savings and efficiency, the growing world population and the aspired higher 'standard of living' will lead to a further in- crease of world energy demand. In this context, almost half of the primary energy demand will continue to be covered by solid fuels, particularly by coal, until 2020 and many years beyond.

This results in the challenge to power plant engineering to implement this increasing energy demand by using new technologies and applying the highest possible conservation of the limited resources of raw materials and the environment.

This includes new materials for higher operating temperatures and, therefore, higher efficien- cies of the power plants, as well as combined power plants that drastically reduce the share of unused waste heat or improved methods for reducing emissions.

Optimizing processes without delay, designing flexible operating conditions, improved use of the load factor of new materials and safely controlling emissions of toxic substances are all tasks that require the use of powerful measurement techniques. For this purpose, devices and systems of process analytics per- form indispensable services at many locations in a power plant.

In spite of all the alternatives, the undiminished increasing world energy demand also makes the expansion of energy recovery from fossil fuels necessary. However, the use of new materials and technologies further increases the efficiency of power plants and further reduces environmental pollution from the emission of toxic substances.

In this context, process analytics plays an important role: It determines reliable and exact data from the processes and thereby allows for their optimization.

Take a moment to review the document below, or if you prefer,  download the "Use of Process Analyzers in Fossil Fuel Plants" PDF file here.

Wednesday, September 6, 2017

Differential Pressure Transmitters and Inferential Measurement

Differential Pressure Transmitter
Differential Pressure Transmitter
(Siemens)
Differential pressure transmitters are utilized in the process control industry to represent the difference between two pressure measurements. One of the ways in which differential pressure (DP) transmitters accomplish this goal of evaluating and communicating differential pressure is by a process called inferential measurement. Inferential measurement calculates the value of a particular process variable through measurement of other variables which may be easier to evaluate. Pressure itself is technically measured inferentially. Thanks to the fact numerous variables are relatable to pressure measurements, there are multiple ways for DP transmitters to be useful in processes not solely related to pressure and vacuum.

An example of inferential measurement via DP transmitter is the way in which the height of a vertical liquid column will be proportional to the pressure generated by gravitational force on the vertical column. The differential pressure transmitter measures the pressure exerted by the contained liquid. That pressure is related to the height of the liquid in the vessel and can be used to calculate the liquid depth, mass, and volume. The gravitational constant allows the pressure transmitter to serve as a liquid level sensor for liquids with a known density. A true differential pressure transmitter also enables liquid level calculations in vessels that may be pressurized.

Gas and liquid flow are two common elements maintained and measured in process control. Fluid flow rate through a pipe can be measured with a differential pressure transmitter and the inclusion of a restricting device that creates a change in fluid static pressure. In this case, the pressure in the pipe is directly related to the flow rate when fluid density is constant. A carefully machined metal plate called an orifice plate serves as the restricting device in the pipe. The fluid in the pipe flows through the opening in the orifice plate and experiences an increase in velocity and decrease in pressure. The two input ports of the DP transmitter measure static pressure upstream and downstream of the orifice plate. The change in pressure across the orifice plate, combined with other fluid characteristics, can be used to calculate the flow rate.

Process environments use pressure measurement to inferentially determine level, volume, mass, and flow rate. Using one measurable element as a surrogate for another is a useful application, so long as the relationship between the measured property (differential pressure) and the inferred measurement (flow rate, liquid level) is not disrupted by changes in process conditions or by unmeasured disturbances. Industries with suitably stable processes - food and beverage, chemical, water treatment - are able to apply inferential measurement related to pressure and a variable such as flow rate with no detectable impact on the ability to measure important process variables.

Thursday, August 31, 2017

Process Instrumentation White Paper: Seven Switch Myths Busted

One Series Pressure and Temperature Transmitter-Switches
One Series Pressure and Temperature
Transmitter-Switches (United Electric)
Summary

With more than 80 years of evolution since its introduction, switch technology as changed significantly enough that some of the common beliefs about switches are no longer true. Seven common myths surrounding switches are analyzed. Recent technology advancements in switch design and how these advancements solve problems in industrial and OEM applications are discussed. Readers will acquire a better understanding of the new technology available to improve control, process efficiency and safety.

1. Blind & Dumb

Prior generations of switches were incapable of displaying process measurements locally, forcing the installation of gauges that created more leak paths and added additional costs. Operators were unaware when installed switches stopped functioning due to welded contacts in the microswitch. Switches required removal from service and manual testing to conform functionality. Often, the control or safety function would go unprotected for days while the switch was in queue to be bench tested, creating an immediate safety concern.

These industry-wide problems inspired manufactures to innovate the next generation of switches that incorporate liquid crystal displays (LCD), presenting local process variable measurements, and integrated internal diagnostics, monitoring the health of the device. The addition of LCDs and device diagnostics increases up me and improves overall plant safety. Original equipment manufacturers (OEM) benefit from a reduction in installed components and a more dependable turnkey product for their customers.

2. Difficult Adjustments

Set point and deadband adjustments were a nuisance for operators and technicians. The instruments were required to be removed from service and calibrated on a bench in the maintenance shop. Installation instructions were not always available for installed devices, leading to wasted me searching for documentation or requesting additional information from the manufacturer. Delicate adjustments were required to achieve desired set points and deadbands, the dead time where no action happens, varied based on the microswitch inside the control. More often than not, instruments were mis- handled leading to premature failure due to inexperienced technicians.

Today’s generation of switches offer electronic platforms that reduce setup and programming to a ma er of seconds. A user interface on the local LCD provides simple prompts that allow users to program switch set points instantly without the need to remove the instrument from the process. Deadband and set point are now 100 percent adjustable, allowing operators to choose the desired range based on the application requirements. No longer are operators required to order and stock redundant devices in the event one failed in the eld. Users now have the flexibility of programming one switch to match many different process requirements.

3. Unsafe in Critical Applications - Not Appropriate for SIS

Industrial process plants are pushing pressure and temperature limits to new boundaries in an effort to stay competitive in a global market. Many of the systems designed 20 years ago were not intended to run at the current process extremes. It is only a ma er of me before these systems fail. Safety instrumented systems (SIS) are being installed to protect the process, people and the environment. These systems require devices that have been rigorously tested by third party agencies to verify the level of safety performance. Mechanical switches, referred to as sensors in SIS, are one of the most common components to fail in these systems. Users and designers require a switch that matches their required system performance level while also being fault tolerant.

Based on the strict performance requirements of SIS, newly introduced hybrid switches integrate the functionality of a switch and a transmitter. The switch portion of the device provides a direct digital output (relay output) to a final element that will instantly bring a process to a safe state in the event of a critically abnormal situation. The analog transmitter signal can be used for trending to determine the health of the device and the process. These new transmitter-switches and recently SIL 2 and 3 exida-certified devices (One Series Safety Transmitter) offer operators a simple and safe product that matches the demanding performance requirements of safety instrumented systems.

4. Problematic in Tough Environments

Whether installed on plant rotating equipment, such as turbines, or on demanding OEM auxiliary equipment, such as pumps or compressors, switches are required to function in tough environments that include shock, vibration, heat and pressure. Vibration is one of the leading causes of electro- mechanical switch failure. Most switches are mechanical in design and utilize a plunger to activate a microswitch. In areas of high shock and vibration, the plunger position can fluctuate and lead to false trips.

New solid-state, electronic switches provide a solution to the common problems with mechanical switches installed in high vibration applications. Because they have no moving parts, these switches can be mounted directly to the equipment or process without connecting impulse lines to keep them isolated from vibration. Industry leading turbine manufacturers and end users operating large compressors in petrochemical plants are experiencing much more reliability and fewer false trips with these new electronic switches, compared to the old mechanical designs.

5. Deploy Electromechanical Designs When Line Power is Unavailable

Most pressure switches sold over the past 80 years were designed to operate without electric power by incorpora ng a sensor that measures pressure by placing force on a plunger that would actuate a microswitch.

The first genera on of digital switches required line power to operate and were not adopted due the unavailability of line power and the cost of wiring. The new genera on of switches operates from leakage current in the circuit when connected to a host device, such as a Programmable Logic Controller (PLC), allowing electronic switches to be drop-in replacements for the old mechanical switches. Today, we have the ability to replace a blind and dumb mechanical switch with a new solid-state, electronic switch that offers a digital gauge, switch and transmitter in one instrument without adding any wiring or hardware.

6. Antiquated Technology


Today’s process plants run their processes faster and ho er than they were originally designed. Ultimately, these plants will have to ini ate modernization projects to support the new demands of the process. Old switches provided users with digital, on-off signals that were either wired to control a piece of equipment directly or sent to a PLC for alarm functionality. As plants go through modernization projects, they restructure control system input/outputs (I/O) to support more analog signals than the digital signals used in the past. Transmitters are commonly chosen and recommended over switches in these new projects, but transmitters do not provide the internal control functionality found in switches.

These modernization projects are costly requiring new equipment, updated wiring, expanded I/O, extensive engineering resources, and costly down me. Users are diligently exploring new ways to reduce overall project costs. The average process transmitter can cost upwards of $2,000 compared to the average process switch costing around $500. Process plants often have 100 to 1,000 switches installed. To upgrade all switches to transmitters could cost a plant up to $1.5 million. Consequently, switch manufacturers researched and developed new electronic switches that are capable of producing both digital and analog signals required by these new modernization projects, while keeping a similar price point to the original mechanical switches installed.

This dramatic savings allows plants to reduce the overall modernization project costs by upgrading the 2nd most likely component (sensor) to fail in a tradional safety system, without upgrading the rest of the safety system and reducing the down me needed to complete the project during a short shut- down turn- around project.

7. The Speed of Response of Transmitters is Faster than Switches


Without question, electromechanical switches are faster than any pressure transmitter on the market. With transmitters, huge amounts of conversions, computations, compensation, and other work must be done to get an accurate signal. Even using today’s high-speed processors, they cannot match the speed of the instantaneous reaction of a mechanical device. The fastest of these devices can be be er than 5 milliseconds while process transmitters can range from 300-500 milliseconds or more. Purpose built transmitters for safety applications designed for speed of response in lieu of accuracy (not needed in safety applications) can be as fast as 250 milliseconds. New solid state transmitter-switches can react in 100 milliseconds or less in the switch mode. If your application requires fast response such as in positive displacement (PD) pumps and turbine trip for over-speed protection, consider new solid-state transmitter-switches over process transmitters.

Recommendations


United Electric Controls has recognized the challenges faced by users and developed new products to match their growing needs. In an effort to reduce plant project costs and help OEMs design and build affordable and reliable equipment for the industrial sector, we have developed a new line of electronic switches that provide drop-in replacement of old mechanical switches. These new switches reduce the costs of plant modernizations. Built-in digital and analog communication provides users the op on of control- ling a piece of equipment locally or sending information back to a central control system for process trending and health, or both.

About this white paper:

UE ViewPoint white papers provide Executive, Business and Technical Briefs written by product, application and industry subject matter experts employed by United Electric Controls.  For more UE ViewPoint papers, visit this link.

Tuesday, August 29, 2017

Introduction to a Closed Loop Control System

Closed Loop Control System
Closed Loop Control System
The video below explains the concept of a closed loop control system, using a steam heat exchanger and food processing application as an example.

A closed loop control system uses a sensor that feeds current system information back to a controller. That information is then compared to a reference point or desired state. Finally, a a corrective signal is sent to a control element that attempts to make the system achieve its desired state.

A very basic example of a temperature control loop includes a tank filled with product (the process variable), a thermocouple (the sensor), a thermostat (the controller), and a steam control valve feeding a tubing bundle (the final control element).

The video outlines all the major parts of the system, including the measured variable, the set point, the controlled variable, controller, error and disturbance.


Contact http://www.ivesequipment.com with any process control or instrumentation requirement. Call 877-768-1600 for immediate assistance.

Friday, August 18, 2017

Level Instrumentation for Your Entire Industrial Plant

Siemens level switches
Siemens level controls.
Whether you are measuring liquids, slurries or bulk solids, Siemens provides the ideal level measuring instruments for every job. Siemens level measurement devices set the standard in their respective disciplines for water, cement, mining, chemical, petrochemicals, food, beverage, pharmaceutical and other industries.



Point Level

Siemens level switches for point level measurement are distinguished by their outstanding performance. Their robust design ensures reduced cost of maintenance, spare parts, and downtime. Siemens level measurement instruments offer easy commissioning, connection to alarm or control systems, long service life, and low operating costs. Technologies include capacitance, rotary paddle, ultrasonic and vibrating.


Continuous

The product portfolio for continuous level measurement covers both contacting and non-contacting measurement. Radar, ultrasonic and gravimetric technologies are available for the non-contacting applications. Capacitance, guided wave radar and hydrostatic technologies are available for the contacting applications. As well, don’t forget that the safest engineered level measurement solution includes switches for back-up, overfill, low level and dry run protection. Technologies include radar, guided wave radar, ultrasonic, gravimetric, capacitance, and hydrostatic.


Interface

Siemens broad portfolio includes a large number of devices for many interface measurement applications, and includes the following products. SITRANS LC500, Pointek CLS 100, CLS 200, CLS 300 and CLS 500 are capacitance instruments for a wide range of tasks. The SITRANS LG uses guided wave radar technology.

Watch the entertaining video below to get a better idea of what level solutions Siemens (and Ives) has to offer.

Thursday, August 3, 2017

Consider Controlled Environment Room Air Flow

walk-in controlled environment room
Air flow characteristics can determine how well a controlled
environment room or chamber performs for an application
Environmental chambers, whether of the reach-in or walk-in variety, all rely on the movement of air within their controlled space to attain performance specifications. Various manufacturers will employ differing strategies for chamber air movement, and the manner in which their designs disperse air flow throughout a chamber of any size can have an impact on the work or process held within the chamber.
This article is about controlled environment rooms, but much of what is included here is also applicable to smaller sized chambers.
The design of air flow in a controlled environment room can be impacted by a number of factors, some of which may be based on specific application requirements, and others that may be influenced by cost, production simplicity, or other factors unrelated to the performance goal of the equipment.

What aspects of controlled environment room air flow bear on performance?

  • Velocity - In the common usage of the term when referring to air flow, the speed of the moving air. Depending upon the air moving equipment arrangement and any dispersion devices, such as perforated suspended ceilings or wall plenums, air velocity can vary throughout a chamber. Users should consider how their work may be impacted by air flow velocity. The storage of material in closed and sealed containers may be impervious to air velocity effects because the "product" within the container is not in contact with the moving air. Plants and insects, on the other hand, are an example of items that may be significantly or severely impacted by air velocity. Higher air velocity at a chamber location exposes that location to more air per unit of time. Desiccation is one possible concern that is exacerbated by increased air velocity. Higher velocity can also be beneficial, even necessary, for some applications. Rapid cooling or heating of materials placed within a chamber is enhanced by increased air movement across the material surface.
  • Volume - The volumetric flow of air through a controlled space or chamber is needed to transfer heat to or from the space in order to maintain temperature control. Much of the air in a controlled environment room is recirculated, with cooling, heating, and in some cases moisture applied to condition the air in the room to the setpoint. The volume of air movement is loosely related to velocity, so increasing volume will result in an increase in velocity unless other design changes are made with respect to how the air is dispersed throughout the room. Higher volume, or turnover rate, contributes to better temperature uniformity in the room. As with velocity, there may be application specific requirements for low air movement. Keep in mind that low air movement creates challenges to the attainment of close temperature control and uniformity. 
  • Pattern - The way in which air is distributed throughout the controlled environment room can impact system performance once materials are placed in the room or process work is commenced. Empty chambers generally perform well, regardless of the air flow pattern, because there is little in the way of a load on the system and no solid materials in place to block or redirect air flow. Consideration should be given to the way in which air is dispersed throughout the work area. Loading patterns for stored product or the placement of work in process should be accommodated by the air flow pattern.
Matching the right air flow characteristics to the work to be achieved in a controlled environment room will result in better overall performance, not just when empty chamber tests are conducted, but when real work is being accomplished.

Share your environmental chamber and controlled environment room requirements and challenges with application experts. The combination of your own experience and knowledge with their specialized technical expertise will yield an effective solution.

Monday, July 31, 2017

Monitoring Catalyst Presulfiding

Catalyst ‘presulfiding’ is a practice which reduces the extent of early catalyst deactivation on by preventing coking (carbon deposits). The procedure involves passing a gas stream containing H2S over the catalyst or into the reaction feedstock.

In order to generate the H2S which will interact with the catalyst, a sulfur carrying agent (e.g. dimethyl sulfide) is injected into the stream. Under high temperature and catalytic reaction, the agent decomposes and releases its sulfur component, forming H2S. The H2S reacts with the catalyst’s metallic surface to substitute sulfur atoms for oxygen atoms.

Read the document below to learn more about monitoring this process with the Applied Analytics OMA-300 H2S Analyzer



Sunday, July 23, 2017

Ives Equipment Business Groups

Ives Equipment organizes its extensive product line into four distinct groups:

Ives Equipment and Controls, providing instrumentation and control products to the chemical, petro-chemical, refining, bulk storage, primary metals, pulp & paper, powergen, gas & oil distribution and OEM markets.

Pharmaceutical, Bio-pharm, and Sanitary, providing hygienic, ultra-pure and sanitary instruments, connectors, fittings, tubing and gaskets to the pharma, bio-pharm, food and beverage, life-science and labortory industries.

Analytical Instruments, used to analyze process material samples and record the data for quality, conformance and compliance.

Water and Wastewater Treatment, providing instruments, analyzers, valves and controls for the transfer, storage, analysis, treatment, and logging of municipal and industrial water treatment systems.

Sunday, July 16, 2017

Definition: Industrial Valve Actuator

pneumatic actuator
Pneumatic actuator on ball valve.
(Worcester)
Actuators are devices which supply the force and motion to open and close valves. They can be manually, pneumatically, hydraulically, or electrically operated. In common industrial usage, the term actuator generally refers to a device which employs a non-human power source and can respond to a controlling signal. Handles and wheels, technically manual actuators, are not usually referred to as actuators. They do not provide the automation component characteristic of powered units.

electric actuator
Electric actuator (Worcester)
The primary function of a valve actuator is to set and hold the valve position in response to a process control signal. Actuator operation is related to the valve on which it is installed, not the process regulated by the valve. Thus a general purpose actuator may be used across a broad range of applications.

In a control loop, the controller has an input signal parameter, registered from the process, and compares it to a desired setpoint parameter. The controller adjusts its output to eliminate the difference between the process setpoint and process measured condition. The output signal then drives some control element, in this case the actuator, so that the error between setpoint and actual conditions is reduced. The output signal from the controller serves as the input signal to the actuator, resulting in a repositioning of the valve trim to increase or decrease the fluid flow through the valve.

electro-hydraulic actuator
Electro-hydraulic actuator
(MIH Trident)
An actuator must provide sufficient force to open and close its companion valve. The size or power of the actuator must match the operating and torque requirements of the companion valve. After an evaluation is done for the specific application, it may be found that other things must be accommodated by the actuator, such as dynamic fluid properties of the process or the seating and unseating properties of the valve. It is important that each specific application be evaluated to develop a carefully matched valve and actuator for the process.

Hydraulic and electric actuators are readily available in multi-turn and quarter-turn configurations. Pneumatic actuators are generally one of two types applied to quarter-turn valves: scotch-yoke and rack and pinion. A third type of pneumatic actuator, the vane actuator, is also available.

For converting input power into torque, electric actuators use motors and gear boxes while pneumatic actuators use air cylinders. Depending on torque and force required by the valve, the motor horsepower, gearing, and size of pneumatic cylinder may change.

There are almost countless valve actuator variants available in the industrial marketplace. Many are tailored for very narrow application ranges, while others are more generally applied. Special designs can offer more complex operating characteristics. Ultimately, when applying actuators to any type of device, consultation with an application specialist is recommended to help establish and attain proper performance, safety and cost goals, as well as evaluation and matching of the proper actuator to the valve operation requirements. Share your fluid process control requirements with a specialist in valve automation, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Contact Ives Equipment for any valve actuator application. Visit http://www.ivesequipment.com or call (877) 768-1600.

Monday, July 10, 2017

Principles of Ultrasonic Flow in Industrial Clamp On Flow Meters

Ultrasonic Flow in Industrial Clamp On Flow Meters
The video below demonstrate the principles applied to industrial clamp on flow meters using the SITRANS FS as an example.

The ultrasonic technology of the SITRANS clamp on flow meter provides highly accurate measurement of liquids and gases. With no pressure drop or energy loss, a wide turn-down ratio and no need to cut the pipe or stop the flow, installation is easy and maintenance is minimal.

For more information about ultrasonic flow meters, contact Ives Equipment at 877-768-1600 or visit http://www.ivesequipment.com.

Friday, June 30, 2017

Happy Fourth of July from Ives Equipment

"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. — That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, — That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness."

THOMAS JEFFERSON, Declaration of Independence

Thursday, June 29, 2017

Refinery Gas Analyses Using Compact Gas Chromatographs and Gas Detectors

The analysis of trace permanent gases has many different fields of application in the petrochemical industry. One of the most important is for controlling the manufacturing process and the product quality. For example, some contaminants as carbon monoxide and carbon dioxide tend to deteriorate the catalysts in the propylene and ethylene polymer grade production.

An instrument for monitoring trace impurities is then required. Many different GC techniques are available on the market. Most of the techniques use a combination of TCD, FID and methanizer for the trace analysis of H2-O2-N2-CH4-CO-CO2 in propylene and ethylene. More precisely, an FID and a methanizer are used to trace CH4-CO and CO2. A TCD with Hydrogen or Helium carrier gas is used to trace O2-N2 detection. Finally, a second TCD with Argon or Nitrogen carrier gas must be added to trace H2 detection. These solutions require complex GC solutions with multiple detectors and multiple gas sources for carrier, fuel and air. On top of that, an FPD must be added in some cases when the trace analysis of H2S is required.

Read the application note below for more information. Contact Ives Equipment at (877) 768-1600 or visit http://www.ivesequipment.com for a consultation.

Thursday, June 22, 2017

Understanding Hydrostatic Pressure

Understanding Hydrostatic Pressure
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.

For more information on any type of pressure instrumentation, visit Ives Equipment at http://www.ivesequipment.com or call 877-768-1600.

Monday, June 12, 2017

An Explanation of Industrial Process Heating Technologies

Boiler providing steam for process heat
Boiler providing steam for process heat.
Process heating technologies can be grouped into four general categories based on the type of fuel consumed: fuel, steam, electric, and hybrid systems (which utilize a combination of energy types). These technologies are based upon conduction, convection, or radiative heat transfer mechanisms - or some combination of these. In practice, lower-temperature processes tend to use conduction or convection, whereas high-temperature processes rely primarily on radiative heat transfer. Systems using each of the four energy types can be characterized as follows:

Fuel-based process heating systems generate heat by combusting solid, liquid, or gaseous fuels, then transferring the heat directly or indirectly to the material. Hot combustion gases are either placed in direct contact with the material (i.e., direct heating via convection) or routed through radiant burner tubes or panels that rely on radiant heat transfer to keep the gases separate from the material (i.e., indirect heating).  Examples of fuel-based process heating equipment include furnaces, ovens, red heaters, kilns, melters, and high-temperature generators.

Steam-based process heating systems introduce steam to the process either directly (e.g., steam sparging) or indirectly through a heat transfer mechanism. 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 used by industries that have a heat supply at or below about 400°F and access to low-cost fuel or byproducts for use in generating the steam. Cogeneration (simultaneous production of steam and electrical power) systems also commonly use steam-based heating systems. Examples of steam-based process heating technologies include boilers, steam spargers, steam-heated dryers, water or slurry heaters, and fluid heating systems.
Electricity-based process heating systems also transform materials through direct and indirect processes. For example, electric current is applied directly to suitable materials to achieve direct resistance heating; alternatively, high-frequency energy can be inductively coupled to suitable materials to achieve indirect heating. Electricity-based process heating systems are used for heating, drying, curing, melting, and forming. Examples of electricity-based process heating technologies include electric arc furnace technology, infrared radiation, induction heating, radio frequency drying, laser heating, and microwave processing.

Hybrid process heating systems utilize a combination of process heating technologies based on different energy sources and/or heating principles to optimize energy performance and increase overall thermal efficiency. For example, a hybrid boiler system may combine a fuel-based boiler with an electric boiler to take advantage of access to lower off-peak electricity prices. 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/throughput, and improve product quality.

For more information, visit www.ivesequipment.com or call (877) 768-1600.

Wednesday, May 31, 2017

An Industrial Valve Positioner that Offers Decisive Advantages

SIPART ® PS2 electro-pneumatic valve positioner
The SIPART ® PS2 electro-pneumatic valve positioner is used to control the final control element of pneumatic linear or part-turn valve actuators. The electro-pneumatic valve positioner moves the actuator to a valve position corresponding to the setpoint. Additional function inputs can be used to block the valve or to set a safety position. A binary input is present as standard in the basic device for this purpose.

The SIPART PS2 smart valve positioner is characterized by significant advantages compared to conventional devices, such as:
  • Only one device version for linear and part-turn valve actuators
  • Simple operation and programming using three keys and a two-line LCD
  • Automatic startup function with self-adjustment of zero and span
  • Manual operation without additional equipment
  • Selectable or freely-programmable characteristics
  • Minimum air consumption
  • Selectable setpoint and manipulated variable limiting
  • Programmable "tight shut-off function"
For more information about the Siemens SIPART 2 positioner download the detailed product brochure from this link,  or visit http://www.ivesequipment.com.