Inline process refractometers are a type of

refractometer A refractometer is a laboratory or field device for the measurement of an Refractive index, index of refraction (refractometry). The index of refraction is calculated from the observed refraction angle using Snell's law. For mixtures, the index ...

designed for the continuous measurement of a

fluid In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...

flowing through a pipe or inside a tank. First patented by Carl A. Vossberg Jr.br>US2807976A
- Refractometer US2549402A, these refractometers typically consist of a

sensor A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

, placed inline with the fluid flow, coupled to a control box. The control box usually provides a

digital Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software ...

readout as well as 4-20 mA analog outputs and relay outputs for controlling pumps and valves. Instead of placing the sensor inline of the process, it can be placed in a bypass, attached by a thin tube. This

measurement Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared to ...

has been an important element in the

process control Industrial process control (IPC) or simply process control is a system used in modern manufacturing which uses the principles of control theory and physical industrial control systems to monitor, control and optimize continuous Industrial processe ...

of the chemical and refining, pulp and paper, food, sugar and pharmaceutical industries for more than a century. For instance, the in-line concentration measurement can be used as a real-time predictive tool for the final

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', '' number concentration'', ...

. A quick and accurate response is needed to optimize production. Cost reduction is possible by reducing the variation of mean average of the product concentration. The cost saving is related to the value of the component being measured. A digital inline process refractometer sensor measures the

refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

and the

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

of the processing medium. The measurement is based on the refraction of light in the process medium, i.e. the critical angle of refraction using a light source. The measured refractive index and temperature of the process medium are sent to the control box. It calculates the concentration of the process liquid based on the

and temperature, taking pre-defined process conditions into account. The output is typically a 4 to 20mA DC output or, increasingly, an

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

signal proportional to process solution concentration, liquid density, Brix or other scale that has been selected for the instrument. The inline process refractometer consists of three primary components: the inline sensing head, the electronics console, and the process adapter. The inline sensing head is mounted on the adapter and contains a prism that scans the process solution through a transparent window and outputs a value relative to the refractive index of the solution. The electronics console houses all control circuitry, microprocessors, digital displays and calibration points and conditions the sensing head signal. The process adapter is the mechanical connection between the inline sensing head and the process piping, and is designed specifically to accommodate the pipe size and application. Inline process refractometers are used primarily in the pulp and paper industry; the food and

beverage industry The drink industry (or drinks industry, also known as the beverage industry) produces drinks, in particular alcoholic beverage, ready to drink and soft drink products. Drink production can vary greatly depending on the product being made. Manuf ...

, the pharmaceutical industry, and the chemical industry as a means to assure consistency and quality. In the

pulp and paper industry The pulp and paper industry comprises companies that use wood, specifically pulpwood, as raw material and produce pulp, paper, paperboard, and other cellulose-based products. Manufacturing process In the manufacturing process, pulp is intr ...

, inline process refractometers are used in the energy recovery from black liquor recovery boilers by accurately measuring solids in the black liquor. In the food and beverage industry, inline process refractometers are used to measure dissolved solids, most often as sugar content, measured in degrees Brix. In the pharmaceutical industry they are used to monitor and control concentration levels during supersaturation, a critical process in crystallization. In the chemical industry they are used in

Hydrochloric Acid Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

applications, Sulphuric Acid applications, and boiler cleaning chemicals processes.

References

{{DEFAULTSORT:Inline Process Refractometer Refractometers