John Dronette 15/08/2017
The cost of shipping dry bulk materials such as grain, coal or sand can be the most expensive part of a product cost especially when you consider the challenges associated with loading rail cars and trucks. For example, if you fill the car too much, there are considerable safety concerns, delays, and even fines that could be incurred. But, if you conservatively leave space in the car to avoid an overfilling, you are paying to ship air!
According to the Association of American Railroads, “A hopper car carrying more than it is designed for can cause a breakdown in the wheel assembly. A loaded car weighing more than the rail line’s capacity can also cause the track to break down. In either case, the breakdown can lead to a derailment with all the danger, inconvenience and expense that such an accident involves.”1 With this in mind, it is understandable that oftentimes, when loading dry bulk materials, the car will only be filled to 90% capacity. However, when you think about it, if all of the rail cars could safely be filled to capacity, it would only take nine cars to ship the product that today takes ten. How many empty rail cars are you shipping?
Is there any way to reduce shipping costs?
According to CSX, on average, transportation comprises 66% of a shipper’s total logistics costs.2 One of the most straight-forward ways to optimize shipping costs is to ensure you are taking full advantage of your truck or rail capacity. Using a single idler belt scale, you can accurately measure bulk material as it is loaded in the car. With an accuracy of +/- 0.5%, rail cars and trucks can be loaded to 99.5% of capacity, reducing total shipping cost by as much as 9% and avoiding the risk associated with overfilling.
You can also get a certified belt scale with an accuracy of +/-0.25% when using a two idler scale, which has the loading capacity up to 99.75%. Both of these belt scales can provide an instantaneous flow rate and an accumulated total of material as it is loaded. By using a batch controller, you are then able to receive a relay output when the rail car or truck is full. This can be used to tell the operator when to stop the filling process.
For more information on how to reduce your shipping costs, please click here: Weighing Systems
What are you doing to esure you are safely getting the most for your shipping dollars?
Herman Coello 27/07/2017
In the first part of this blog, I talked about closed pipe flow and the benefits and disadvantages it can have. In part two, I’d like to focus on open channel flow and how this option can be used to measure water and wastewater flow.
Measuring flow through an open channel is a popular choice for water/wastewater applications. It’s easy to see why, with ease of installation and maintenance over time. In open channel flow, the use of a primary measurement device, such as a weir or flume, along with a non-contacting level measurement device is used to determine the flow. There are several choices for the primary measurement device as well as the level device. Let’s take a look at just a few of the choices for this type of flow.
The Primary Measurement Device (PMD) is a key component of open channel flow measurement. A great deal of thought should be put into the selection of the primary measurement device. The flow rate that you have today may not be the flow rate that you will have tomorrow and must be considered to avoid the purchase of an inadequate system. Other items to consider are the accuracy of the PMD, maintenance and the fluid to be monitored. Installation of the PMD is critical for the proper reading of the open channel flow meter selected to measure the head of the flow. Improper installation or sizing of the PMD will impact the overall performance of the system.
It’s not just flow.
The level measurement system should also be given a great deal of thought. There are a couple of options in technology here such as radar or ultrasonic, and both options have their positives and negatives.
Radar has come a long way in the last few years and is a proven technology. The cost of a radar device has decreased and performance has increased. Radar level transmitters are easy to install and configure, and usually have a low cost of ownership once deployed. However, radar technology does have a few drawbacks when compared to other level technologies. Radar instruments do not have relay outputs, totalizers or displays that can be easily seen when installed over the weir or flume. Radar transmitters are mostly used for level applications and when used to determine flow, it is often required that a head vs. flow characterization curve is entered in the instrument itself or on a PLC. Radar also does not react as quickly to changing head levels as other technologies. Finally, the designs used for open channel flow measurement have a small horn antenna. This coupled with the operating radar transmitter frequency results in signal with a wide beam angle. This is an undesirable attribute when applied in narrow flumes and weirs.
Non-contacting ultrasonic level is one of the most popular technologies when it comes to open channel flow. When correctly applied and installed, an accuracy of ±1 mm can be achieved. For the highest accuracy, an external temperature sensor, separate from the transducer, is recommended to ensure the speed of sound is accurately adjusted for the varying temperatures of the day. Ultrasonic level transmitter devices usually have a variety of communication options and outputs to meet the needs of the end user. They are easy to configure via the user graphical interfaces and have many of the flow calculations for the various PMDs pre-programmed. Most ultrasonic level flow meters have a separate transducer and controller. The ultrasonic level controller can be mounted separately, hundreds of feet away from the transducer, to allow easy access for configuration, routine monitoring, and capture of the flow data.
So, as you can see, there are many options to choose from and it depends on your set-up. For volumetric flow in a closed pipe, you need to know if the liquid is conductive or not, a given in the water industry. If you are using the flow meter for clean or for water with significant suspended solids, you’ll need to consider whether a closed pipe or open channel is the right solution for you.
What is the right technology to use once I have decided on open or closed pipe?
Eric Heilveil 20/07/2017
Siemens’ Coriolis flow meter has a vast number of benefits and can be a highly advantageous solution to many flow measurement applications. The SITRANS FC410 flow meter is the lightest and most compact Coriolis system worldwide. With the FC410, you can reduce skid size, fit multiple units into the tightest areas and simplify installation into both new and existing applications. Sounds great, right? Well, it is…however, that is not to say that Coriolis flow meters are without flaws.
While every technology has certain challenges, process noise and dual-phase flow are at the top of the list for Coriolis.
Coriolis meters hate process noise. No matter if that noise is from a pump, a variable drive or just footsteps on a cat walk, noise can easily upset the precise measurement of a Coriolis sensor. Since the Coriolis sensor is carefully monitoring and measuring micro-variations in the flow tubes’ motion, the smallest of external vibration can be picked up and sampled, and thus can introduce an error in flow measurement.
The challenge for the Coriolis sensor is to maintain a high degree of sensitivity while at the same time metering in a sampling of protection from noise.
How do you address this?
The solution is a vast array of filters that can modify the digital signal or the analog outputs to present the desired nature of I/O. Typically, filters are used to slow or average the output signals to stabilize them. In more advanced states, the filters monitor a vast array of data produced in the modern Coriolis sensors and then use adaptive algorithms to learn and contour the output as required.
To learn more about Coriolis’ challenges and how you can address them, please click here.
Herman Coello 13/07/2017
Throughout my time in the industry, the one question that always gets brought up is, “With all of the options and technologies available, what is the best way to measure water and wastewater flow?”
This is a tough question to answer because there are so many options and each has their pros and cons. As government requirements and regulations are becoming more stringent, it is important to know the advantages and disadvantages of both because there is a great need to measure the flow rate throughout not only in the water/wastewater and irrigation industries but in all industries.
As your available options, you can choose from closed pipe flow and open channel flow before getting into the specific types. Let’s begin with closed pipe flow.
Closed pipe flow
In this type of application, there are several types of products and technologies that can be used to measure flow. The options for measuring flow include the use of magnetic and ultrasonic flow meters, pressure transmitters and other less practical and/or frequently used technologies such as capacitance, Time Domain Reflectometry (TDR ), and paddle wheel technologies to measure and totalize the flow.
Magnetic flow devices are one of the most commonly used technologies for measuring flow. The technology is accurate and well understood, and it offers a non-intrusive design because it has no mechanical moving parts. Magnetic flow meters are durable and some models can be submerged or buried without issue. Magnetic flow meters are usually not affected by solids that may be in the flow stream; however, they can be affected by air in the pipe and can give false readings if the pipe is not kept full. They can also be affected by stray electrical currents from Variable Frequency Drives (VFDs) that interfere with the magnetic field of the flow meter. Proper grounding helps to mitigate external influences. That is why it is key to use the best installation methods to ensure that the proper operation and readings are received from the magnetic flow meter.
Ultrasonic flow meters are another common means for measuring flow in a closed pipe. They are easy to install and can be installed on large enclosed pipes without interrupting the process. They are accurate and, with the proper installation, can yield accuracy in the 1% range of flow. This technology offers the ability to measure the flow of liquid in either an in-line or a non-intrusive clamp-on design. With both Transit Time and Doppler designs this technology can be used on clear liquids or liquids with entrained gases or solids. However, ultrasonic flow devices based on Transient Time technology can be affected by solids in the flow and in such applications, a magnetic flow meter is the right choice where suspended solids are present.
Pressure transmitters are an economical way to measure flow. The technology is widely used through all industries and easily deployed. Volumetric flow is obtained by measuring the pressure at two different points in a tube or pipe and this is done using a differential pressure transmitter. There are a variety of primary elements like orifice plates, pitot tubes, Venturi tubes, etc. to cover pretty much any application. They have readily available communication interfaces and are easy to calibrate in the field. Unfortunately, pressure devices are not always the most accurate compared with other technologies and they do not have the turn-down capability of other devices. Pressure measurement devices can suffer from calibration drift and biological buildup, causing errors in the reading if they are not maintained over time.
On the other hand, open channel flow is a popular choice for water/wastewater applications.
Why is it so popular for these applications?
Join me for my next blog and find out! We’ll be diving into open channel flow in more depth.
What pros and cons have you found while using closed pipe flow technologies?
Christine Baumann 08/06/2017
The Automation Summit draws more than 500 attendees each year and for good reason! Instead of companies dictating what they think you should know, the Automation Summit brings in people from the field to share their experiences, the applications they used, what technologies they implemented and, most importantly, what worked for them and could be applicable to others.
User-led presentations are complimented by a handful of sessions hosted by Siemens field employees who are willing to share their best practices. Rather than a sales pitch, these classes are conducted by men and women who have the experience. Students will have hands-on access to equipment and all courses include a certificate that can be submitted for professional development hours.
With over 50 user-led presentations and many other activities, it may be tough to prioritize your “can’t miss” list. The conference runs June 26-29, 2017, in Boca Raton, Fla., so you still have a little time to read up on it. To lend a hand, here are a few tips to keep in mind.
- Technology Café.
This is a one-stop-shop where you’ll experience the entire scope of Siemens automation, controls and drives portfolio, and interact with Siemens experts in an open, informal setting. There are lots of demos here, and lots of opportunities to ask questions about your process and how to enhance it.
- Training Sessions.
With over 14 sessions, you can have your pick of the lot. And, you get PDH credits too. A list of training sessions, along with a brief description of the content, can be found on pages 17-18 of the program guide: 2017 Automation Summit Program.
- Breakout Sessions.
This is the meat of your visit. There are sessions on best practices, discussions on digitalization and cyber security, using cloud-based technology, safety techniques … if you can think of it, we’ve probably got you covered I can’t say which one is best, but take a look and see what grabs your attention! You can see the complete list of sessions here.
Interested to learn more?
Click here to read more on the benefits and features of the Automation Summit.
What steps are you taking to enhancing your plant?
- Technology Café.
Tom Pendergras 06/06/2017
The dry solids flow meter uses the impact of measuring through flow of material. The material impacts a sensing plate and, in turn, pushes on a load cell or linear variable differential transformer (LVDT). From the output of load on the load cell or LVDT you get a rate of flow. This could be in tons per hour or pounds per hour. Because it is measuring the impact force, the bulk density should remain within +/-1 lb. per cubic foot (PCF). As a result, it is essential to conduct material tests to ensure that it doesn’t negatively affect the impact on the plate.
What sort of scenarios can affect the impact on the plate?
From my experience, there are primarily six scenarios that can affect the impact on the plate.
- The bulk density of the product.
A good example would be dry corn versus wet (or fresh) corn. They are the same product but they have a very different bulk density. Dry corn has a bulk density around 50 pounds PCF and fresh corn from the field has a bulk density of around 56 pounds PCF. Dry corn is hard and will flow easier than wet corn. Wet corn is softer and will have a different impact onto the plate
- The size of the product can also affect how the material impacts the sensing plate.
If the product comes in as a powder one day and the next day the same product is a half inch in size, the material will flow differently causing the sensing plate to react differently. The material size can also affect the density of the product, which can affect the force of material that strikes the plate.
- How far the product falls before it hits the impart plate.
If the product is dropped one foot from the plate versus six feet from the plate, you will get a difference in impacted force onto the plate.
- How the product is fed to the sensing plate.
If the product is fed by a screw conveyor or a rotary feeder the output flow of these types of feeders will pulse, which will cause the plate to react differently.
- Air flow.
If the is air flow in the system is significant, the air will push onto the plate showing flow when truly there is no product flowing onto the sensing plate.
If you are using a dust collection system, it can act as the reversal to air flow and not allow the plate to move because the vacuum is so great.
With all of these scenarios, you can see how any one of these changes can affect the rate outcome.
This is why simply hanging a test weight on the dry solids flow meter cannot cover all six of these scenarios in the factory.
Finally, the best way to test the flow meter is to run multiple material tests. Once you are satisfied with the outcome of your tests, you can hang the test weight to see what that weight represents and use that number to keep the unit calibrated.
How do you ensure your dry solids flow measurements are accurate?
- The bulk density of the product.
Jonas Norinder 06/06/2017
Perhaps you have heard people talking about how the biofuels industry has been slowing down in recent years or that it’s an industry in recession. Well, that is surely not the case. In 2015, almost 15 million gallons of ethanol was produced across 199 ethanol refineries and three more plants were under construction(1). This was the best year ever for the ethanol industry, and 2016 was said to be looking slightly better. Most of the ethanol produced has been blended into gasoline to satisfy a maximum 10% ethanol content by volume in most fuel grades in the U.S.
What goes into making ethanol?
In order to make ethanol, an intricate process that involves fermentation and distillation needs to be accurately controlled and monitored to ensure that the various ethanol purities can be achieved. And although the process may sound very familiar to some of you, we’re not talking about making beer. As for any process that requires monitoring and control, accurate process sensors throughout the process is required as well as a Distributed Control System that can control the process from start to finish.
How do you ensure that your plant’s process is cost-efficient and running smoothly?
Have questions about your plant’s set-up or want to be sure you’re up to code? Want to learn more about the latest technology? Or are you wondering if your plant running as cost-efficiently as possible? Bring your questions with you to the Fuel Ethanol Workshop 2017 in Minneapolis, MN, June 19-22, 2017. Siemens Industry will be in booths 625, 627, 724 and 726 along with Trident Automation, our Automation Solution Partner. We’d love to have a chat with you and help answer some of your questions and concerns!
(1)Source: Renewable Fuels Association Ethanol Outlook 2016 - https://www.ethanolrfa.org/wp-content/uploads/2016/02/Ethanol-Industry-Outlook-2016.pdf
Joshua Ramos 11/05/2017
What is the difference between internal and external temperature compensation, and how can it affect you?In ultrasonic level instrumentation , a controller measures the time-of-flight of the sound wave produced by an ultrasonic transducer for the round trip between the transducer and the target (material level). The speed of sound is the distance travelled per unit time by a sound wave. In dry air at 68°F, the speed of sound is 1,129 ft/s....
Factors that contribute to the calculation of sound velocity are temperature and the medium it is traveling through such as air or a gas. To measure distance using time-of-flight, you have to know two things accurately:
- How long did the round trip take?
- How fast was the sound wave traveling?
So why is temperature compensation an important factor with ultrasonic level technology?
First, we must understand what occurs to the sound velocity with temperature. The hotter the air is, the faster the sound velocity becomes. The colder the air is, the slower the sound velocity.
Modern ultrasonic transducers have built in temperature sensors . You might also need an external temperature sensor as well. So, how do you choose whether to go with an internal or external temperature sensor? Let’s make one thing clear: whether it is internal or external sensor, they both compensate the speed of sound as the temperature changes.
Years ago, I had a conversation with someone who was using ultrasonic level transmitters to measure the level of corn, potato flakes and flour in a silo. His issue was that the units were not measuring accurately and the transmitters were reporting a lower level. He stated that he encountered these issues every year during the summer months. After visiting the site, we found that the transducers were on top of metal silos and exposed to the heat of the sun. As the day progressed, the temperature registered by the transducer increased more than the actual temperature in the vessel. This was a result of the transducer being in direct contact with sunlight.
It is a good practice to utilize a sun shield whenever instruments are in direct sunlight, and more so when the external heat source can influence a level measurement. The integral temperature sensor in the transducer is surrounded by the transducer housing and a potting compound. Due to this, it takes more time to heat or cool the integral temperature sensor to meet the actual temperature inside a vessel. In this case, the solution was to bypass the integral temperature sensor and use an auxiliary temperature sensor inside the vessel to detect the air temperature in the process.
This issue could have been resolved with a sun shield and thus, the integral temperature readings would have not been influenced by external factors.
Alternatively, you can use an auxiliary temperature sensor. The auxiliary temperature sensor is not an expensive solution, but it is also not as practical or economical as using a sun shield. An auxiliary temperature sensor requires a cable run from the controller to an available port on the vessel. The latter is not always ready available, which can lead to additional costs if a retrofit is needed.
If you have an application where faster temperature response is required, than an auxiliary temperature sensor is the preferred recommendation. The critical nature of the application may or may not require temperature compensation beyond the ultrasonic transducer capabilities.
Have you encountered inexplicable discrepancies in level monitoring that made you question what you are using to measure?
Tom Evanto 04/05/2017
For the last 17 years, I’ve worked in level and weighing instrumentation as an Application Engineer. During that time, I have occasionally seen situations where a level sensor or a level transducer has been unreliable due to excessive condensation build-up on its face plate.
How do you know if your level transducer or sensor is not performing correctly?
Operators at most sites perform rotational checks often enough to be able to identify when their instrumentation isn’t performing correctly. When it comes to condensation issues, you’re going to be able to spot the problem pretty early on because your level instrument will either lose its level signal or start acting erratically when overwhelmed by too much condensation. The excess condensation will be apparent on the sensor itself. After your transmitter dries, the level device should start working again without issue. However, depending on the environment your instrumentation is located in, you may have dust or some powdery material that, when moistened or wet, cakes onto the transmitter and potentially causes monitoring issues.
Although it is nearly impossible to remove condensation in some environments, we have found some ways to mitigate or even avoid the adverse effects caused by condensation.
- Radiant barrier works by preventing radiation cooling of the sensor to the point where the temperature is below the dew point on a clear night. Radiant barrier is more effective on a clear night than on a cloudy night but can still help to some extent.
- Tilting the transducer slightly one or two degrees does the job in most cases.
- Applying Rain-X on the tilted transducer face will also assist in clearing/condensate build-up from the transducer face.
These ideas are sensor installation dependent and will often require experimentation to determine what works to reliably avoid or significantly reduce condensation and therefore improve the sensor performance. There is a cost benefit factor in order to implement one or more of these ideas that must be weighed by the end user.
Keep in mind the need to resort to the suggestions above would only be in an extreme case of condensation. By design, the pulsating action on the face of the transducers is sufficient to vaporize most condensation that otherwise will form on the sensor. But, if your application results in excessive condensation, the above suggestions are a good approach to consider tackling such nuisances.
What applications do you have issues with due to condensation?
Jack Roushey 28/04/2017
Flow measurement is more critical in more areas of a plant than ever before. Do you have places in your process where you now wish you had included a process flow measurement? Are there problems in those locations where making a quality measurement is difficult? Things like process lines you can’t shut down, pipes you can’t cut into, specially lined pipe or exotic pipe materials because of the nature of the process, non-ideal pipe runs, high pressure process lines or difficult process mediums?
These issues and more can make the addition of a flow measurement point seem impossible. But is it really?
Did you ever consider or think that you could just clamp a device to a pipe and measure flow and measure it accurately? What are you currently using for flow measurement and meter verification in your plant?
Clamp-on ultrasonic flow can help with many of the adverse conditions listed above and the new Siemens SITRANS FS230 digital platform clamp on ultrasonic flow meter can expand on the traditional versatility of clamp-on technology. Now you can measure flow where...
- You have less than desirable pipe straight run by using either a multiple path ultrasonic and/or by utilizing the Siemens patented pipe configuration software.
- Deal with pulsating flow: the FS230 offers the fastest update rate in the industry.
- Complicated set ups are no longer required. The menu driven wizards of the FS230 makes setting up the transmitter easy, even for the most challenging applications.
- You need an understanding of what’s going on in your process measurement. Siemens offers diagnostics that open the window into your process, providing variables not offered by any other flow meter on the market.
- You have a wide range of pipe sizes where measurement is required. Installation is available on line sizes from 0.5” to 394”; and because it is clamp-on technology, it isn’t affected by pressure in the process line.
- Cutting into the pipe is not an option. Our clamp-on meter is designed to mount easily on the outside of the pipe, and doesn’t require the shut down of your process for installation.
Just when you thought there wasn’t a measurement solution for the areas in your plant that may not have been designed around flow instrumentation, you can now take advantage of the fact that Siemens has engineered solutions to alleviate these problems.
To learn more about the SITRANS FS230, please click here.