Get to Know Electron Machine Corporation

Electron Machine Corporation, headquartered Umatilla, FL, manufactures industrial, inline, process refractometers. As a vertically-integrated manufacturer, we have complete control over the time it takes to manufacture our instruments providing the highest levels of service and support to our customers. Superb quality control is attained by adapting modern technology and practices to existing designs. These include in-house microprocessor and DSP software design, surface-mount PC card design and assembly, 3D CAD/CAM designing, CNC machining, and MIG/TIG welding. Additionally, our founder's innovative nature is still with us as we continue to research and develop new products.

Learn more about Electron Machine at https://www.electronmachine.com or by calling 352-669-3101.

Technical Sales Representatives: The Often Underutilized Asset

Work with your technical sales rep.
It will pay off in ways you haven't imagined.

Process refractometers are sold with the support of sales engineers working for the local distributor or representative. By realizing what these specialists have to contribute, and taking advantage of their knowledge and talent, you will save time and money and experience a better project outcome.

Consider these contributions:

Product Knowledge:
Sales engineers, by the nature of their job, are current on new products, their capabilities and their proper application. Unlike information available on the Web, sales engineers get advanced notice of product obsolescence and replacement. Also, because they are exposed to so many different types of applications and situations, sales engineers are a wealth of tacit knowledge that they readily share with their customers.

Experience:
As a project engineer or leader, you may be treading on fresh ground with a refractometry requirement for your current assignment. You may not have a full grasp on how to handle a particular challenge presented by a project. If this is the case, call in the local technical sales representative - there can be real benefit in connecting to a source with past exposure to your current requirement.

Of course, sales engineers will be biased. Any solutions proposed are likely to be based upon the products sold by the representative. But the best sales people will share the virtues of their products openly and honestly, and even admit when they don’t have the right product. This is where the discussion, consideration and evaluation of several solutions become part of achieving the best project outcome.

Whatever your stake in an upcoming or ongoing project, it's highly recommended you develop a professional, mutually beneficial relationship with a technical sales expert, a problem solver. Look at a relationship with the local sales engineer as symbiotic. Their success, and your success, go hand-in-hand.

PID Control: The Basics

PID diagram (courtesy of Wikipedia)

PID is short for "proportional plus integral and derivative control", the three actions used in managing a control loop. Process loop controllers use one, two or all three of these to optimally control the process system. PID control is used in a wide variety of applications in industrial control and process system management.

Many types of PID controllers exist on the market and are used for controlling temperature, pressure, level and flow. PID control is also used in industrial, inline refractometers to control process variables such as Brix, Percent Solids, Dissolved Solids, Specific Gravity Units, and Refractive Index. 

Here is a brief explanation of the three actions that make up PID control.

Proportional Control Action (P): The controller output responds in proportion to error signal. The characteristic equation for this action is:

• Where, Kp is called proportional gain, e is the error magnitude and B is the output from controller when there is no error. It is also called bias. 
• In a proportional controller, the value of gain is set as required by the process and can be varied from 0 to ∞. 

Integral Control Action (I): The control system will respond if the error is present over a period of time. This type of control action is called Integral Control Action. The integral action is defined mathematically as:

• Where, e= error, Ti= Time interval of integral action.
• Purpose of integral action is to provide adequate control action on varying demands of process. In this type of action, output varies as per the time integral of error. This action does not exist independently and always associated with proportional control. 

Derivative Control Action (D): To achieve a stable process, wide proportional band and low integral action are set. Due to these settings, the control system can be too slow. If large system disturbances occur over a wide interval, PI controllers are inadequate. These large system disturbances can be managed if the controller output responds not only to the magnitude of deviation, but also to the rate of change of deviation. Derivative control action is that control action. 

Today's process controllers are much easier to set the PID, thanks to auto-tuning algorithms. What used to be a very time consuming and tedious job can now be done with the push of a button and allowing the controller to "learn" the process dynamics. PID controllers minimize error and optimize the accuracy of any process.

For more information on the use of closed loop control with industrial inline process refractometers. contact Electron Machine Corporation by visiting http://www.electronmachine.com or calling 352-669-3101.

Understanding Error in Process Measurement

Instrumentation calibration is a procedure through which three general types of errors can be encountered. A typical signifier for a need of instrument recalibration is if the instrument is performing in an incorrect manner. This situation serves as a good way to showcase different types of error related to error analysis.

The three major category of errors regarding measurement are gross errors, systematic errors, and random errors. The first two categories of error, gross and systematic, are related to the two main elements of process control: controller and instrument. Gross errors are a product of the process controller or operator incorrectly evaluating the instrument value, with the best prevention of gross error being careful review of data both while recording and interpreting it.

Systematic errors impact every reading from a particular instrument, and are typically cause for instrument recalibration. Zero errors, where the instrument does not return to the predetermined zero value after each reading, are systematic errors because the same error in measurement is being displayed each time. Lastly, random errors impact instrumentation readings due to causes which are either unknown or simply unpredictable, meaning the error is both not able to be duplicated and is not a result of gross error. Random errors can be challenging to deduce due to both their singularity and their potential lack of a clear cause.

The previously mentioned zero error, also known as a zero shift calibration error, is typified by the resulting readings being offset at the same percentage. For example, a pressure transmitter which is functioning incorrectly as the result of a zeroing error can be corrected by a corresponding zero adjustment. After the adjustment and the transmitter being calibrated back to the correct zero point, the error will disappear. Another common type of systematic error is span shift calibration error. Unlike the zero error, span error can impact readings from the instrument repeatedly, but not necessarily identically. Similarly, by correcting the corresponding setting on the transmitter, in this case the span adjustment, the instrument can be correctly programmed once again by measuring the readings against a properly configured reference.

Hysteresis error occurs when the instrument in question returns erroneous responses as the input variable changes. The antidote to this kind of systematic error is to check the instrument against a pre-defined set of calibration points, first by increasing the input, and then subsequently decreasing the input in sequence to determine how the instrument responds as the input changes. Mechanical friction has been known to be a common culprit for hysteresis errors.

Understanding the capabilities and limitations of whatever instrument is relied upon for delivering process information is essential to successful operation.

Bleaching of Pulp in the Paper Making Process

The purpose of the bleaching process is to enhance the physical and optical qualities (whiteness and brightness) of the pulp by removing or decolorizing the lignin. Two approaches are used in the chemical bleaching of pulps. One approach called brightening, uses selective chemicals, such as hydrogen peroxide, that destroy chromatographic groups but do not attack the lignin. Brightening produces a product with a temporary brightness (such as newspaper) that discolors from exposure to sunlight or oxygen. The other approach (true bleaching) seeks to almost totally remove residual lignin by adding oxidizing chemicals to the pulp in varying combinations of sequences, depending on the end use of the product. This creates a longer lasting (sometimes permanent) whiteness, but it weakens the fibers and reduces sheet strength. The most common bleaching and brightening agents are chlorine, chlorine dioxide, hydrogen peroxide and sodium hydroxide.

Typically, the pulp is treated with each chemical in a separate stage. Each stage includes a tower, where the bleaching occurs; a washer, which removes bleaching chemicals and dissolved lignins from the pulp prior to entering the next stage; and a seal tank, which collects the washer effluent to be used as wash water in other stages or to be sewered. Bleaching processes use various combinations of chemical stages called bleaching sequences.

The first stage in the bleaching process is the chlorination stage, whose primary function is to further delignify the pulp. Chlorine reacts with lignin to form compounds that are water-soluble or soluble in an alkaline medium, which aids in delignifying the pulp before it proceeds to the next bleaching stage.

The next stage after chlorination is typically the extraction stage. This stage and the remaining stages serve to bleach and whiten the delignified pulp. The extraction stage removes the chlorinated and oxidized lignin by solubilization in a caustic solution.

Chlorine dioxide is often used in bleaching, either in the chlorination stage (as a substitute for some of the chlorine usage - chlorine dioxide substitution) or as an additional chlorine dioxide stage. Chlorine dioxide has 2.63 times greater oxidizing power (on a pound per pound basis) than chlorine and is used for nearly all high brightness pulps.

The next stage is the actual bleaching stage. Hypochlorite is a true bleaching agent that destroys certain chromophobic groups of lignin. It also attacks the pulp so high cellulose degradation occurs in Kraft pulp. Application of hypochlorite to Kraft pulp is usually used only as an intermediate stage of the sequence or to produce semi-bleached pulps. In the bleach process, residual chlorine must be removed through washing in vacuum washers.

Abstracted from Washington State
Air Toxic Sources and Emission
Estimation Methods

Sulfite Pulping

Pulping is the term used for the process which separates wood fibers. Chemical pulping, dissolving the lignin in the wood to create a pulp, is the most commonly used pulping process. Chemical pulping creates higher sheet strength than mechanical pulping; however, yields 40 to 50 percent pulp, where mechanical pulping yields 95 percent pulp.

The two main types of chemical pulping are the more common sulfate pulping (most commonly known as Kraft pulping) and sulfite pulping. Kraft pulping accommodates a variety of tree species, recovers and reuses all pulping chemicals, and creates a paper with a higher sheet strength. Sulfite pulp, however, is easier to bleach, yields more bleached pulp, and is easier to refine for papermaking. The major difference between the two types of chemical pulping is the types of chemicals used to dissolve the lignin.

Sulfite Pulping

The concept of sulfite pulping was created in the United States in 1867, however it was not used in a mill until 1874 by a Swedish chemist who was probably unaware of the U.S. Patent (MacDonald, 277). Sulfite pulping produces a lighter pulp than Kraft pulping. It can be used for newsprint, and when bleached can be used for writing papers and for the manufacture of viscose rayon, acetate filaments and films, and cellophane.

Description of Process 

Sulfite pulping follows many of the same steps as Kraft pulping. The major difference in sulfite pulping is that the digester “cooks” with a mixture of H2SO3 (sulfurous acid) and HSO3 ion in the form of calcium, magnesium, sodium, or ammonium bisulfate). The pulp continues on through the same processes as in the Kraft pulping process.

However, the chemicals separated from the pulp in the washers may or may not go into a recovery process. Chemical recovery in sulfite pulping is practiced only if it is economical. If chemical recovery does occur the liquor goes through an evaporator and then to a recovery furnace. Here, smelt is not formed, but ash and SO2 are formed.

Abstracted from Washington State

Air Toxic Sources and Emission

Estimation Methods

MPR E-Scan Deemed RoHS Compliant and Earns CE Marking

Electron Machine Corporation engaged F2 Labs for the technical assessment of the MPR E-Scan using the European standard, EN 50581:2012 Technical documentation for the assessment of electrical and electronic products with respect to the restriction of hazardous substances, to determine compliance with the RoHS Directive 2011/65/EU, and has determined Electron Machine Corporation can claim compliance to the RoHS Directive 2011/65/EU for the subject equipment based upon the supplied documentation.

RoHS stands for Restriction of Hazardous Substances. RoHS, also known as Directive 2002/95/EC, originated in the European Union and restricts the use of specific hazardous materials found in electrical and electronic products.

This certification applies to each portion of the MPR E-Scan (IS), which includes the Console, Cable, Barrier Box, and Sensing Head; along with all components that each of these major subassemblies of the MPR E-Scan contain.

For more information, please contact Electron Machine at 352-669-3101 or by visiting this link.