Kevin van Dijk
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For most people the classic summer treat is ice cream. Around 7 billion gallons of ice cream and other related frozen desserts are produced every year worldwide, with production peaking (as you might expect) in the summer months, according to the International Dairy Foods Association. Yet, the moment you consume an ice cream, you will probably not wonder how this delicacy is being made. To get that perfect ice cream, a mass flow controller is often used.

What does ice cream have to do with mass flow meters?

Ice cream contains many different ingredients, such as fat, sugar, milk solids, an emulsifying agent, flavoring and sometimes coloring agents. But there is one main ingredient that you may not have thought about, probably because you can’t see it—air. Ice cream is made by freezing and simultaneously blending air into the ingredients. So why is air so important?

If you have ever had a bowl of ice cream melt, and then refroze it and tried to eat it later, it probably did not taste very good. Moreover, if you leave a carton of ice cream out in the hot sun and let it melt, the volume of the ice cream would simply go down. Air makes up anywhere from 30% to 50% of the total volume of ice cream, therefore aeration in the production process is crucial.

The amount of air in ice cream (often called overrun) affects the taste, texture and appearance of the finished product. Higher aeration will produce a tastier and smoother ice cream. A side effect of adding air to ice cream is that it tends to melt more quickly . Thus, for attaining an optimal structure of the ice cream, it is important to have a stable inlet air flow in the production process with a constant cream/air ratio. This can be achieved by using a mass flow controller.

To get an idea of the effect of air on ice cream, think of whipped cream...Whipped cream - cream with air - has a different texture and taste than plain cream. To learn more about this process, please read the story of our guest blogger Hans-Georg Fenzel, where he explains how air is used to create whipped cream.

The process of whipping ice cream into shape

To guarantee the right consistency and structure which ensures a full flavored ice cream, the cream must contain the correct proportion and composition of air bubbles. Hence, aeration mixer manufacturers use a mass flow controller to dose an exact amount of air into the cooled mixer. Such a mass flow controller will ensure a continuous air delivery, proportional to the cream flow . The mass flow controller must be capable of maintaining its performance regardless of any possible back pressure variation. Occasionally, a check valve is mounted at the mass flow controller’s downstream. If inlet pressure drops, such a valve will avoid ice cream back stream into the instrument. A pressure meter is also used with the purpose of monitoring the inlet pressure.

Image description Flow scheme of whipping ice cream process

The SEM (Scanning Electron Microscope) picture below shows the ice cream microstructure. Air bubbles are a critical ingredient. Experts claim its optimal size, distribution and quantity are one of the secrets for having a creamy texture recipe. Hence, according to meet such demands, Bronkhorst has provided efficient solutions for enhancing continuous aeration processes.

Image description Ice cream microstructure

So, the next time you head to the ice cream parlor with your friends, be sure to keep in mind the importance of Bronkhorst when it comes to that delicious refreshment.

Image description Bronkhorst EL-FLOW Select flow meter

Angela Puls
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In our daily life we use plastics or polymers in many different forms whether as a disposable product such as packaging film or as a long-lasting component in the automotive industry, in construction or in sports equipment and toys.

Nowadays, plastics are tailor-made for the respective application, depending on the properties desired. In this way, properties such as hardness, mold ability (or formability), elasticity, tensile strength, temperature, radiation and heat resistance can be adjusted as well as the chemical and physical resistance can be adapted to the desired function.

This large variety can be modified within wide limits by the choice of the basic building blocks (macro molecules), the production process and additives. The respective macromolecules are polymers of regularly repeating molecular units. The type of crosslinking and the used additives determine the final properties of the material. Last year, the world-wide production of plastics for bulk materials and films was over 300 million tons (source: BMBF) of which almost one third was produced in China. Europe and North America follow with slightly less than 20 percent each.

Precise dosing for operational efficiency and minimization of unnecessary waste

Typical additives in the plastics industry are antistatic agents, dyes, flame retardants, fillers, lubricants, colorants, stabilizers and plasticizers. Many of these additives are liquid. Precise dosing of the additives leads to operational efficiency and the minimization of unnecessary waste.

Additives are frequently added by use of needle valves, which is inexpensive, but always has a risk on malfunction because of fluctuation within the process (e.g., pressure and temperature). In particular the use of plasticizers is increasingly critical since some of these substances are directly absorbed by human beings or accumulate in the food chain.

With the proven CORI-FILL dosing technology, Bronkhorst offers an easy-to-use setup to ensure the required accuracy and reproducibility. By combining a mini CORI -FLOW with a pump or a suitable valve, fluids can be dosed continuously or as a batch into the reactor with high reproducibility. These systems can be integrated or used as an add-on in already existing processes and production lines.

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5 Reasons why additive dosing with a Coriolis instrument supports process efficiency for plastic manufacturers

  • No need for (re)calibration in the field – fluid independent flow measurement and control
  • Gas and liquid can be measured with the same sensor
  • Ability to measure undefined or variable mixture
  • Multi parameters
  • The CORI-FILL™ technology features an integrated batch counter function and enables direct control shut-off valves or pumps

Watch the principle of operation of the Coriolis Mass Flow Meter with dosing pump.

Want to learn more about improving dosing and metering pump performance? Please read the blog of James Walton where he discusses dosing pumps in combination with Coriolis mass flow controllers.

Visit Bronkhorst at the Compounding World Expo 2018 Stand number: 602

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Vincent Hengeveld
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Efficiency and yield in a process require a stable gas flow. This gas flow can be measured and controlled by a thermal mass flow controller. As a Product Manager at Bronkhorst High-Tech, I experienced that various external factors can have influence on the measurement accuracy and control stability of mass flow controllers (MFCs). Some examples of external factors are:

  • Temperature fluctuations
  • Line-pressure fluctuations. These fluctuations can occur due to reduced pressure in a gas cylinder or due to cross talk between multiple flow controllers. How does Bronkhorst solve these problems, and what solutions do we offer?

Cross talk with mass flow controllers

What is cross talk? Cross talk typically arises when multiple mass flow controllers are positioned in close proximity in the same pipe, or installed upon the same rail or frame. The line-pressure from a gas regulator is affected by the flow demand of the flow controllers. When the flow instrument is changing its setpoint, it will affect the line-pressure. Due to this pressure change, the flow measuring section in a conventional flow controller is affected, indicating an incorrect flow measurement that does not represent the actual flow through the MFC. The smaller the nominal flow of the flow controller, the bigger the effect will be to a setpoint change of a larger, parallel installed MFC.

Static and dynamic pressure compensation

Static pressure compensation is the compensation for slow pressure changes, for example the slowly reduced pressure from a gas cylinder. By integrating a pressure transmitter to the mass flow controller, together with an on-board conversion algorithm, real-time calculation of the actual fluid properties can be performed. For semi-caloric measurement the density, viscosity, thermal conductivity and heat capacity are used in the calculation. Under influence of pressure and temperature, these properties change. Thus, actual temperature and pressure are measured and processed, resulting in accurate flow measurement and control stability.

Dynamic pressure compensation is the compensation for rapid pressure changes. This can occur when a higher-flow mass flow controller on the same supply line changes setpoint, an undesired effect which is also known as ‘cross talk’. The moment that these rapid pressure changes are identified by the pressure sensor, the valve control will be adjusted accordingly so that the flow remains stable.

Image description Dynamic compensation, insensitive to pressure changes

Stable flow control with on-board conversion

The on-board conversion algorithm makes it possible to convert the stored calibration fluid into one of the 25 on-board gases (multi-fluid multi-range functionality). The actual measured temperature and pressure is used in the on-board conversion model to compensate for changes in the process conditions. This leads to a more reliable and accurate conversion and control stability.

Image description More simple setup with mass flow meter containing ‘pressure insensitive’

Benefits for the user

  1. Firstly, due to the improved and accurate flow measurement and control, optimized and more constant process conditions are possible, resulting in an improvement of your process yield.
  2. Secondly, ease of installation since there is no need for exactly providing/meeting the process conditions the instrument was ordered for.
  3. Thirdly, because the supplied line pressure becomes less important for the accuracy and control stability of the instrument, less accurate components or even reduction of components in the supply line are needed. This allows saving costs on, for example, a pressure regulator.

Image description New EL-FLOW Prestige PI (Pressure Insensitive) now available

Armand Bergsma
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Dome loaded back pressure controllers are often used in processes where constant pressure is needed in a (chemical) reactor. Electronic pressure controllers are very effective when it comes to automating such processes.

‘We use the latest Bronkhorst electronic pressure controller for our Equilibar dome loaded back pressure controllers. This allows us to regulate two control valves,’ says Armand Bergsma, owner of Pressure Control Solutions in Veenendaal (NL).

Dome loaded back pressure controllers

How does a dome loaded back pressure controller work? The process pressure is set by applying the required pressure to the reference side of the controller at a one-to-one ratio. The reference pressure can be applied using a manual reduction device, or for process automation, you can use electronic pressure controllers.’

‘Until recently, we used single-valve electronic controllers to get the right pressure levels, then to reduce pressure, we added artificial leaks. Although this works very well in practice, the downside is that this solution requires us to continuously use inert (high-pressure) gas.’

‘This configuration is fine for low-pressure applications using a compressed air network, or high-pressure applications where the customer provides a centralised high-pressure network. However, it can be a problem if such facilities are not available.’

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‘If there is no centralised high-pressure network, you can use 200 or 300-bar gas cylinders. The reactors used to test catalysts usually only need a pressure of 150 to 180 bar, so you should not use more than 50 to 20 bar respectively from a 200-bar nitrogen cylinder in order to maintain maximum process pressure. If you want to work for an extended period, you will have to find another way to limit the consumption of dome gas.’

(Industrial) Process Pressure Controller

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‘Together with Bronkhorst Nederland, I looked for a solution to reduce the consumption of dome gas. We now combine our Equilibar dome loaded back pressure controller with the new Bronkhorst EL-PRESS Process Pressure Controller. This device features an integrated PID controller, which means we can now regulate two control valves, reducing the consumption of dome gas by quite a lot.

This pressure controller opens the control valve located upstream of the pressure sensor. Meanwhile, the downstream valve remains closed, which causes the reference pressure to increase. Gas consumption during the pressure build-up is negligible. The control valve located downstream of the pressure sensor is only opened once the pressure is lowered. Naturally, the upstream valve remains closed when this happens. By choosing the right valve (orifice size) and PID settings, we can quickly or slowly increase and/or reduce the dome pressure, depending on our needs.’

Pressure control with two control valves for dome loaded pressure controllers

The Bronkhorst Process Pressure Controller (PPC) doesn’t just reduce gas consumption, it also offers excellent stability. Thanks to the clean pure gases that are used, processes that combine an Equilibar precision dome loaded pressure controller and the PPC can control pressure stability at a rate that is even better than 0.1%.

‘The process side of the dome loaded pressure controller is often used to process aggressive reactants and by-products at high temperatures. For these severe applications, the Equilibar can be manufactured from chemically inert materials such as SS316, Hastelloy, Zirconium and Monel. The multiple-orifice design is capable of controlling gases and liquids as well as multi-phase flows.’

* Learn more about all our absolute, relative and differential pressure controllers

Jos Abbing
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Experiencing harsh industry applications for many years now, I have seen several unpleasant results of corrosion. The global corrosion costs are huge, more than 2000 billion Euros according to NACE. Almost 60% occurs in industrial use, with the chemical, process, and oil & gas industry accounting for the majority share.

These types of industries are coping with demanding environmental and process conditions in production and operation. This includes associated services, such as in heat-transfer systems, transmissions, and distribution and storage of gases and liquids. Prevention or control of corrosion by the use of inhibitors often proves to be an economic solution.

Using a low flow control system can help you dose more accurate amounts of corrosion inhibitors. Accuracy is crucial here; it greatly influences the efficiency and minimizes environmental impact of an inhibitor system.

General corrosion factors

In fact, all metals have a tendency to corrode or dissolve to some degree. Corrosion is a natural process converting metals to a more chemically stable form. The main process medium and the environment have a major impact on corrosion factors such as oxygen, water content, acidity levels, temperature and other factors.

Image description Corrosion Factors

Influencing these main drivers allow corrosion to be stopped or slowed down sufficiently and it is here that inhibiting can play an important role.

Desgining in corrosion resistantance by selection of best compatible material and combinations, additional material thickness, and application of protective coatings may have an initial technical preference to inhibiting. Additionally, metal damage by erosive particles, fatigue, mechanical stress or cavitation may cause corrosion processes which cannot be controlled sufficiently with the use of inhibitors.

However, prevention or control of corrosion by inhibiting often proves to be an economic solution in lots of other situations, improving life time and operational costs with minimum environmental impact. Some relevant examples are to follow.

Examples of metal corrosion

Corrosion can have different drivers and causes:

Image description Anode-cathode principle

Galvanic corrosion requires two different metals that are in electrical contact. When exposed to an electrolyte, a migration of ions from the anode to the cathode causes a release of free electrons. The more noble metal (cathode) is protected and the more active metal (anode) tends to corrode.

Electrochemical corrosion, involving the release of electrons of anodic parts, is related or involved in a lot more corrosion processes, such as concentrated cell (crevice) or pitting corrosion.

Another example is chemical corrosion, which is often induced by strong oxidants, and may not be accompanied by the flow of electric current.

Biological corrosion is caused by the presence and growth of micro organisms. Their direct presence or their corrosion product caused by metabolic activity of the organisms damages the metal which can also lead to pitting or crevice corrosion.

Inhibitor classifications

The task of an inhibitor substance is to slow down or prevent the damage caused by corrosion to acceptable levels. Most corrosion inhibitors used are multi-component mixtures. Below some important examples for (liquid phase) inhibitors.

Image description Inhibitor classification

Environmental or scavengers inhibitors control corrosion by reducing or removing the corrosive properties in the medium, often involving oxygen reduction.

Interface inhibitors form a protective film on the metal, isolating the metal from the corrosive medium.

Anodic inhibitor will facilitate the formation of passivation layer blocking the anodic process. The critical concentration of the inhibitor is important to secure effectivity and to prevent corrosion acceleration caused by a too high concentration of inhibitor.

Cathodic inhibitor will decrease the corrosion rate by reduction of oxygen concentrations or increase in the over potential of hydrogen liberation (poison) and precipitate (deposit) on specific cathodic areas (precipitator), forming a protective film.

Mixed or organic inhibitors can moderate both anodic and cathodic principle e.g. by adsorption, chemisorption and film formation. An adsorption processes (physical) is relatively quick but are also more easily removed from a surface, requiring careful control. Chemisorption is a chemical adsorption process, caused by a reaction on an exposed surface, creating an electronic bond of a chemical on the adsorbed surface. The higher the concentration the greater the protection with a limit to a maximum. By exceeding the maximum concentration, corrosion acceleration is often observed.

Enabling smarter dosing control

A corrosion inhibitor system will add small concentrations of (bio) chemicals into the process. The effectiveness of an inhibitor system greatly depends on the correct injection amount. The correct injection amount is also influenced by the environmental and process conditions.

Image description Ex Zone 1 scale inhibitor with Coriolis mass flow controller

The required weight fraction of traditional mix of biocides, other inhibitor substances, agents, surfactants and pH regulators may vary e.g. between 0.001 and 0.1 weight %. The inhibiting system may inject in parts per million (PPM) to achieve low concentrations to be effective. Both continuous and shot dosing systems are used, based on the situation.

Traditional methods often involve manually tuned piston pumps with check valves. Verification of flow, by changing the stroke length, is often carried out empirically with stop-watch and graduated gauges. This traditional approach makes it virtually impossible to actively compensate to changing process conditions, such as temperature changes (caused by day/night). The result may be the worst-case flow setting, increasing chemical use, environmental impact and also cause over-dosing (!) of chemicals under normal operation conditions.

Accurate flow control

Accurate flow control enables cost effective applications with less environmental impact. High accuracy and high turndown ratio is achieved based on pure mass measurement with mini CORI-FLOW. This mass flow meter can also directly control valves and pumps by on-board PID control and can be further optimized with PLC and HMI control extending both performance and flexibility.

Coriolis dosing system

Our Coriolis dosing system approach, with digital communication, enables real-time monitoring, control and logging of injection rates. This allows online checking of flow rates and instantaneous re-setting of the required flow rate. Asset management and preventive maintenance is supported with several active diagnostics such as on-board status alarms enabling, steering monitoring, density alarm changes, single or multi point totalization for costs calculations, empty tank alarm, and pump protection shut down.

Bronkhorst has been supporting field applications and R&D research projects with extensive know how on low flow fluid handling. The ongoing research for even more environmental friendly solutions, such as biodegradable based inhibitors, is gladly supported by us.

Corrosion inhibitors are also used in other kind of industries such as public water systems. Check our blog about how phosphates are added to our drinking water as corrosion inhibitor to prevent the leaching of lead and copper from pipes and fixtures.

Bronkhorst Coriolis mass flow controllers can be an ideal solution for corrosion inhibitors. Have a look at our Coriolis product line.

Rob ten Haaft
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It might surprise you but already since the Middle Ages, people are interested in the smell of a person’s breath. In those days it must have been quite a challenge to investigate but as early as those days diseases like diabetes (associated with a sweet, acetone odor) and liver failure ( a fish-like smell) were diagnosed upon one’s breath. I will not discuss the treatments during those years; let’s say that much has improved since the Middle Ages. For example, nowadays, we use Ion Mobility Spectrometers (IMS) to measure Volatile Organic Compound (VOC).

At the beginning of the 21st century, research studies show that dogs are able to detect cancer by smell. The dogs are trained to detect different kinds of cancer in exhaled breath of human patients, as they can smell with a sensitivity of parts per trillion (ppt). To give an example: the scent of one cc of blood, diluted in 20 Olympic sized swimming pools can still be detected by the dog. It was concluded that dogs are probably discriminating between breath samples based on a specific breath odor but it is still unknown what odor or mix of compounds dogs detect. The detection of cancer by trained dogs seems to be obvious when you think about it, but it requires a lot of training of the dogs and it is still unknown why not all cases of cancer are detected.

Volatile Organic Compound (VOC)

This is the reason that researchers have started to develop analyzers that can do the dog’s job. In the last few years it was discovered that Volatile Organic Compounds (VOC) can be distinctive biomarkers in the diagnosis of human diseases. Volatility is the tendency of a substance to evaporate, therefore Volatile Organic Compounds are organic compounds that will easily evaporate or sublimate at room temperature.

The exhaled human breath contains a few thousand volatile organic compounds and the composition of the VOCs is used in breath biopsy to serve as a biomarker to test for diseases such as lung cancer.

An increasingly popular analytical technique to measure VOC’s is Ion Mobility Spectrometry (IMS). This technique is ideal for analysis in medical applications since the analysis is fast, not affected by humidity, highly sensitive, and operates at ambient pressures. This makes the technique very suitable for portable or Point of Care application.

Ion Mobility Spectrometry (IMS)

The Ion Mobility Spectrometer operating principle is based on the drift, or time-of-flight, of ions that are formed in the reactant section. The ions travel, supported by an electric field, through the drift tube where they encounter a drift gas (N2 or Air). The shape and the charge number of the ion will make it easier or harder to flow through the drift gas which will cause a separation of the ions in the sample and after detection give an IMS-spectrum as shown in Figure 1.

Image description Figure 1 : Ion Mobility Spectrometer with spectrum

Mass Flow Controllers

To deliver the gases to the drift tube, Bronkhorst has the knowledge and experience to supply the right products. Our products address the specifications that are important for controlling the gases in Ion Mobility Spectrometry such as:

  • cleanliness,
  • small instrument size,
  • fast response, good reliability,
  • low power and
  • low cost of ownership. Our MEMS (Micro Electro Mechanical Systems) based instruments, such as the IQ+FLOW thermal flow meters, are very suitable for Ion Mobility Spectrometry.

Image description IQ+FLOW thermal flow meter

Are you interested to read more about mass spectrometry (MS) and how mass flow controllers and evaporation is used for Electrospray Ion source, check our blog ‘A closer Ion them’.

Check our success story using IQ+ gas flow meters and pressure controllers for a gas chromatography application.

If you have questions or ideas on Ion Mobility Spectrometry other analytical applications that involve controlling of gas or liquid, feel free to contact us.