Common Industrial Refractometer Applications and Processes

Refractometers measure a dissolved material's concentration in a liquid. There are numerous prospective applications in various industrial sectors. Even if the production, environmental and processing processes differ from sector to sector, despite the end product, all fundamental unit operations and control strategies are approximately the same. Outlined below are several of the more common applications and processes where inline industrial refractometers are used.

Crystallizers

In industry, crystallizers are used for liquid solid separation. They are an important component of chemical processing equipment as they can generate high-purity products from a relatively low energy input. To determine the right seeding point (evaporative crystallizer) or to detect when crystals start to form (cooling crystallizer), the refractometer controls the liquor concentration.

Reactors

Process reactors are used for commercial production applications in adhesives processing, agriculture, chemical processing, cosmetics, food and beverage production, paints and coating production, paper and pulp processing, pharmaceutical and medical production, plastics and thermoplastics processing. The real-time progress of a reaction can be followed using inline refractometers, either through the leveling out of key process variables, or the reaching of a single component's targeted refractive index value.

Evaporation

An evaporator is a tool used in a method to transform the liquid form of a chemical substance such as water into its gaseous / vapor form. During that phase, the liquid is evaporated or vaporized into a gas form of the intended substance. Inline refractometers provide real-time data of concentration changes in the process media.

Reverse Osmosis

Reverse osmosis (RO) is a water purification method that removes ions, unwanted molecules and bigger particles from drinking water using a partially permeable membrane. Inline refractometers provide real-time data of concentration changes in the process media.

Spray Dryers

Spray drying is a way to produce a dry powder from a liquid or slurry by drying quickly with a warm gas. This is the preferred drying technique for many thermally sensitive products like foods and pharmaceuticals. A consistent distribution of particle size is a reason why certain industrial products such as catalysts are sprayed. Process refractometers monitor the concentration of the feed line to the spray dryer, ensuring correct particle size after drying, improving quality, and increasing product shelf life.

Dissolving Tanks

Dissolving tanks are used to dissolve solids into a liquid, thereby changing the concentration of the solution. Refractometers provide continuous measurement of the concentration components in solution as the solute dissolves into water or solvent. Information for dissolving rate and dissolved solids is provided instantly through the refractometer and corresponding electronics.

Solid / Liquid Extraction

Solid / Liquid extraction method is a very popular method in the pharmaceutical, cosmetic and food industries to acquire natural ingredients such as natural raw material flavors and fragrances. Inline refractometers are used to detect the amount of extracted substance (dissolved solids) in the liquid after the extraction process. The measurement by the refractometer is not affected by undissolved solids, only by the dissolved matter, making it ideal to follow extraction efficiency.

Cooking Processes

The art, technology, science and craftsmanship of preparing food for consumption is cooking. The large scale production of juices, jams, jellies, dairy, and fruits in modern production facilities require automation and control instrumentation for quality and efficiency. Sugar is a key component in many foods that needs to be monitored. The inline refractometer is used to monitor refractive index of the product, and when when cooking is complete. Inline refractometers determine the end of the cooking process based on qualitative measurements of dissolved solids.

For more information about using applying the refractive index to industrial applications, contact Electron Machine Corporation by calling 352-669-3101 or by visiting https://electronmachine.com.

Industrial Inline Refractometers for Sucrose, Fructose and Dextrose

The Electron Machine MPR E-Scan is perfectly suited for sugar applications. The refractometer directly measures dissolved solids, which can be easily converted to Brix.

In sugar refineries, the MPR E-Scan can be used to monitor and control Brix measurement from the beginning of the evaporation stages up to the seed point of crystallization.

The suggested adapter for most installations is either a 316S/S in-line type adapter or a 316S/S vacuum pan adapter. If coating may be an issue, a steam or hot water wash nozzle can be provided.

Sanitary-type adapters designed and manufactured to appropriate 3-A Sanitary Standards are also available if needed.

Refractometer for Food & Beverage Industries from Electron Machine Corporation

Introduction to Industrial Instrumentation

Engineer adjusting a
process controller measuring 
the refractive index of a process.

Instrumentation is the science of automated measurement and control. Applications of this science abound in modern research, industry, and everyday living. From automobile engine control systems to home thermostats to aircraft autopilots to the manufacture of pharmaceutical drugs, automation surrounds us. This chapter explains some of the fundamental principles of industrial instrumentation.

The first step, naturally, is measurement. If we can’t measure something, it is really pointless to try to control it. This “something” usually takes one of the following forms in industry:

• Fluid pressure
• Fluid flow rate
• The temperature of an object
• Fluid volume stored in a vessel
• Chemical concentration
• Machine position, motion, or acceleration
• Physical dimension(s) of an object
• Count (inventory) of objects
• Electrical voltage, current, or resistance
• Refractive Index

Once we measure the quantity we are interested in, we usually transmit a signal representing this quantity to an indicating or computing device where either human or automated action then takes place. If the controlling action is automated, the computer sends a signal to a final controlling device which then influences the quantity being measured.

This final control device usually takes one of the following forms:

• Control valve (for throttling the flow rate of a fluid)
• Electric motor
• Electric heater

Both the measurement device and the final control device connect to some physical system which we call the process. To show this as a general block diagram:

Process control loop

The common home thermostat is an example of a measurement and control system, with the home’s internal air temperature being the “process” under control. In this example, the thermostat usually serves two functions: sensing and control, while the home’s heater adds heat to the home to increase temperature, and/or the home’s air conditioner extracts heat from the home to decrease temperature. The job of this control system is to maintain air temperature at some comfortable level, with the heater or air conditioner taking action to correct temperature if it strays too far from the desired value (called the setpoint).

Industrial measurement and control systems have their own unique terms and standards. Here are some common instrumentation terms and their definitions:

Process: The physical system we are attempting to control or measure. Examples: water filtration system, molten metal casting system, steam boiler, oil refinery unit, power generation unit.

Process Variable, or PV: The specific quantity we are measuring in a process. Examples: pressure, level, temperature, flow, electrical conductivity, pH, position, speed, vibration.

Setpoint, or SP: The value at which we desire the process variable to be maintained at. In other words, the “target” value for the process variable.

Primary Sensing Element, or PSE: A device directly sensing the process variable and translating that sensed quantity into an analog representation (electrical voltage, current, resistance; mechanical force, motion, etc.). Examples: thermocouple, thermistor, bourdon tube, microphone, potentiometer, electrochemical cell, accelerometer.

Example of a transducer.
In this case, a
Refractive Index transducer.

Transducer: A device converting one standardized instrumentation signal into another standardized
instrumentation signal, and/or performing some sort of processing on that signal. Often referred to as a converter and sometimes as a “relay.” Examples: I/P converter (converts 4- 20 mA electric signal into 3-15 PSI pneumatic signal), P/I converter (converts 3-15 PSI pneumatic signal into 4-20 mA electric signal), square-root extractor (calculates the square root of the input signal).
Note: in general science parlance, a “transducer” is any device converting one form of energy into another, such as a microphone or a thermocouple. In industrial instrumentation, however, we generally use “primary sensing element” to describe this concept and reserve the word “transducer” to specifically refer to a conversion device for standardized instrumentation signals.

Transmitter: A device translating the signal produced by a primary sensing element (PSE) into a standardized instrumentation signal such as 3-15 PSI air pressure, 4-20 mA DC electric current, Fieldbus digital signal packet, etc., which may then be conveyed to an indicating device, a controlling device, or both.

Example of a transmitter and/or
controller. In this case, refractive
index signal conditioning electronics
to modify the transducer signal,
and optionally, provide a control
output to a final control element.

Lower- and Upper-range values, abbreviated LRV and URV, respectively: the values of process ^oC and its URV would be 500 ^oC.
measurement deemed to be 0% and 100% of a transmitter’s calibrated range. For example, if a temperature transmitter is calibrated to measure a range of temperature starting at 300 degrees Celsius and ending at 500 degrees Celsius, its LRV would be 300

Zero and Span: alternative descriptions to LRV and URV for the 0% and 100% points of an instrument’s calibrated range. “Zero” refers to the beginning-point of an instrument’s range (equivalent to LRV), while “span” refers to the width of its range (URV − LRV). For example, if a temperature transmitter is calibrated to measure a range of temperature starting at 300 degrees Celsius and ending at 500 degrees Celsius, its zero would be 300 ^oC and its span would be 200 ^oC.

Controller: A device receiving a process variable (PV) signal from a primary sensing element (PSE) or transmitter, comparing that signal to the desired value (called the setpoint) for that process variable, and calculating an appropriate output signal value to be sent to a final control element (FCE) such as an electric motor or control valve.

Final Control Element, or FCE: A device receiving the signal output by a controller to directly influence the process. Examples: variable-speed electric motor, control valve, electric heater.

Manipulated Variable, or MV: The quantity in a process we adjust or otherwise manipulate in order to influence the process variable (PV). Also used to describe the output signal generated by a controller; i.e. the signal commanding (“manipulating”) the final control element to influence the process.

Reprinted from Lessons In Industrial Instrumentation by Tony R. Kuphaldt under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.

Understanding the Use of Inline Refractometers in Food and Beverage Production

Inline refractometers are used
for jam and jelly production to
ensure consistency and quality.

This post is intended to give a basic understanding of the use of inline refractometers in commercial food and beverage production. 

Refraction

According to Wikipedia, "Refraction is the change in direction of wave propagation due to a change in its transmission medium."

To understand more clearly, consider this. If you place a pencil in a jar of standing in water and look through the jar, it appears to be broken at the water line. When you add sugar to the water, the pencil appears to bend even more. The reason for this is because light travels slower in water than through air. When you dissolve materials (sugar) in the solution, the light will travel even slower.  Understanding this basic concept allows you to understand how you can measure, and therefore control, the concentration on a material in a solution through the use of refraction.

Refractive Index

The refractive index (RI), is the ratio between the speed of light in vacuum and the speed of light in a given media. It determines how much light is bent, or refracted, when entering a material. The Refractive Index of air is 1.0003, and the RI of most gases, liquids, and solids is between 1 and 2.

Refractive Index is defined as:

• RI= Speed of Light in Vacuum / Speed of Light in a Particular Medium

Applying Refraction to Food and Beverage Processing

Food and beverage industries prefer to use their own units rather than the index of refraction for controlling quality of their product. Examples are measuring sugar content in tomato products, citrus juices, and jams and jellies. These industries prefer to use the % Brix scale, which refers to the sugar concentration. Refractive Index is easily converted to % Brix units through simple calculations.

Inline Refractometers for Large Scale Food and Beverage Production

Industrial inline refractometers directly measure the Refractive Index of process fluids and then display the reading in any number of customer-desired units such as Brix, Percent Solids, Dissolved Solids, etc. 

Inline refractometer in food and beverage process
highlighting sensing element and electronics console.

There are two primary components to an inline refractometer, the electronics console and the sensing head.  

The electronics console usually contains a display of some type, and provides a standard output such as 4-20mA. Optionally, there may be some form of networking protocol such as HART® or RS-232/422. 

The sensing head is installed in line by mounting the prism assembly in a pipe and inserting this pipe section in the process line. Vessel mounting is accommodated by having the prism assembly inserted in a flange that can be attached to a storage tank or mixing tank. 

For more information on any commercial or industrial application for inline refractometers, contact visit Electron Machine at http://www.electronmachine.com or call 352-669-3101.

Inline Refractometers Used in Commercial Food and Beverage Production

Refractometers assist in consistent quality
in commercial food and beverage processing.

All commercial food brands must assure a level of quality their users have grown to expect. A change in their product's quality can trigger a change in the customer's buying habits. The ability to provide consistent quality and taste is key to happy customers and continued sales.

For producers of many commercial food products, such as wine, fruit juice, jams, and carbonated beverages, a critical way to control quality is by measuring "Brix".

Brix is a unit of measurement used to to establish the concentration of sucrose and other sugars (as well as other dissolved solids) in aqueous solutions. When evaluating sweetness, one degree Brix (symbol °Bx) is defined as 1 gram of sucrose in 100 grams of solution, and represents the strength of the solution as percentage by mass.

Inline refractometers provide commercial food,  juice and wine producers critical information about the make-up of their product. Many commercial food processing plants use refractometers to blend their products to consistent Brix level, thus assuring consistency. Because the dissolution of sucrose and other sugars in a solution changes the solution’s refractive index, measuring this change can be used reliably to measure consistency and quality. A refractometer works by shining an LED light source from a range of angles, through a product sample, onto a prism surface. By measuring the difference in the reflection and refraction of the light source, a critical angle can be determined and the refractive index can be accurately calculated.  This measurement and calculation can be done accurately, repeatably, and with speed, so inline refractometers have proven themselves reliable instruments for the measurement of Brix in all food processing applications.

Typical applications for the measurement of sucrose, fructose, and dextrose by an inline refractometer:

• Soft drinks, fruit juices, dairy.
• Apple sauces, jams and jellies.
• Beer wine, coffee, and tea.
• Vegetable oils.
• Tomato pastes and sauces.
• Honey.

For any questions about the use of refractometry in food and beverage processing, contact Electron Machine Company at 352-669-3101 or visit http://www.electronmachine.com.

Industrial Refractometry: The Very Basics

Most objects can be evaluated quantitatively and qualitatively. Determining the number of cars on a highway is a quantitative calculation; determining the color of a car is a qualitative calculation. In the process control industry, analyzing the qualitative and quantitative natures of a product is one of the most important steps in ensuring a manufacturer is delivering their clients not only the best product, but making sure that every product made is the best product.

If you’ve ever cracked open a crisp, cold beer on a Sunday, sampled a great wine, or asked yourself, “why does this soda taste so good?” you’ve had experience with what the process control industry calls “industrial refractometry.” Pink Floyd’s album cover for Dark Side of the Moon, where a beam of light hits a prism at a certain angle and then exits the other side in multiple colors, illustrates a core component of refractometry. Refractometry measures the speed at which light passes through an object.

Here’s how evaluating a substance with a refractometer works: a substance is placed on top of a prism. Then, a beam of light shines through the prism and reflects through the substance. The refractometer compares how much slower (or faster) light travels through the object compared to the speed of light through air. The comparison allows the evaluator to determine qualitative aspects of the substance, such as the density or concentration. For standardization purposes, the speed at which light passes through air has a refractive index (RI) value of 1. If a substance has an RI value of 1.16, light travels 16% quicker through air compared to the substance on the prism. Depending on the color and temperature of the reflected light, even more qualitative characteristics of the substance can be determined.

Electron Machine Inline Industrial Refractometer

While the process won’t always help determine what exactly a substance is (different substances can have the same RI values), refractometry is essential in determining how something is. If a corporation knows the RI value of a liquid product, they can ensure each iteration of said product is precisely made, quantitatively and qualitatively. When two substances are being combined to create one resulting substance, refractometry can show exactly how close the combined substance is to being an accurate fusion.

Overall, refractometry is used by industrial companies as a control method. Industry professionals use refractometers to perform evaluations; these refractometers range from small, hand-held devices to full-powered, computer-controlled precision machines which measure the quality of every product coming out of on an assembly line. Refractometry is an objective way to prove standards are being met while achieving production excellence, making refractometry an extremely valuable tool for industrially geared businesses of almost every size.

So, the next time you want to combine coffee and creamer, if you know the refractive value of the best cup of coffee, you could use your own refractometer to measure how close you are to the perfect morning blend!

Control Boiler Cleaning Chemicals with Inline Refractometry

Inline industrial refractometer for boiler cleaning acids.

Chemical cleaning has been considered a necessary part of boiler maintenance for many years. The objective of a chemical cleaning is to safely remove all the deposits from the inside of the boiler tubes. Proper chemical cleaning removes deposits from the inside of boiler tubes which improves the boiler heat rate, reduces tube failures and improves the stability of boiler chemistry. However, chemical cleaning can cause severe damage to the boiler if proper chemical dilution is not maintained.

The MPR E-Scan allows chemical cleaning companies the ability to control acid dilution to strict specification. This insures the proper cleaning dilution is achieved while reducing the risk of over shooting the target control point causing costly damage. By installing the instrument in-line after the dilution point, the MPR E-Scan provides real time control, trending and data logging information to operators insuring the required chemical dilution is achieved and remains constant. This will reduce the overall time needed to meet target dilution, saving time and minimizing the boiler downtime.

The MPR E-Scan can be constructed of various alloys to ensure a long service life in a harsh chemical environment. By utilizing the instrument to control and monitor the cleaning solution, chemical cleaning companies can assure customers that proper dilution was met and maintained. When the job is completed, the cleaning company can provide their customer with documentation of both the process dilution and temperature throughout the entire cleaning process.

Application Features:

• Measurement and temperature output with data logging
• Continuous accurate control of acid dilutions to meet target
• Trend graphing
• Functional status indication of monitored parameters Error and Warning light indications
• Time reduction
• High-resolution color display 

Additional design features:

• Data logging documentation for dilution and temperature
• Multiple product ranges and configurable set points.
• Sapphire Prism
• Daylight visible color display
• NEMA 4X
• Stainless-steel CNC machined sensing head
• 4-20mA & RS-232 outputs
• Configurable alarm points: high/low, setpoint/ deviation, etc.