pH and ORP Analyzers

Yokogawa & Nouryon Co-Innovation Leads to New pH-Analyzer
 
 

Measurement of pH in high purity water presents many difficulties. Yokogawa's pH instrument's design success comes from addressing the unique challenges of the application.

The proliferation of microorganisms and the resultant formation of slime is a problem which commonly occurs in aqueous systems. Problematic slime producing microbes may include bacteria, fungi and/or algae. Slime deposits typically occur in many industrial aqueous systems including cooling water systems, pulp and paper mill systems, petroleum operations, clay and pigment slurries, recreational water systems, air washer systems, decorative fountains, food, beverage, and industrial process pasteurizers, sweetwater systems, gas scrubber systems, latex systems, industrial lubricants, cutting fluids, etc.

Industry:Refining, Food and beverage, Power, Oil and Gas, Pulp and Paper, Chemical

Dairy wastewater is a mixture of organic compounds, suspended solids, fats, and bacteria that can produce a film or coating on equipment in the process. 

Control of sodium chloride (NaCl) concentration at a salt dissolver where solid salt is dissolved in water, is highly important because of the electrolysis efficiency. A conventional way of measuring the concentration of supersaturated NaCl solution had been performed by using non-contact type sensors (e.g., γ-ray density meter) since NaCl, impurities, and precipitates are in the solution.

There are many points in the processing of edible fats and oils that benefit from the use of analytical measurements. Inductive conductivity, contacting conductivity, gas density, and pH can be utilized to increase the quality of the end product, as well as protecting expensive processes.

Clean-in-place (CIP) is the system designed for automatic cleaning and disinfecting in the food & beverage, pharmaceutical, and chemical industries. Tanks and piping are cleaned and sterilized with various cleaning solutions, fresh or hot water, or steam after manufacturing products is completed.

Problems at the wet end of a paper machine can rarely be corrected downstream. That is why monitoring and controlling pH in pulp stock is critical to the paper-making process. Essentially, at every stage in the manufacture of paper, correct pH values play a vital role. Variations in the pH value at the headbox have a negative effect on the quality of the paper produced. Proper monitoring ensures minimizing plugging and fouling problems that occur with pH measurements in paper mills. 

Cyanide-bearing wastewater from mining and electroplating facilities and certain types of chemical plants is toxic and must be treated by oxidation with chlorine or chloride to bring the cyanide concentration within regulatory limits.

Industry:Electrical and Electronics

The treatment of wastewater from pulp and paper plants is a serious environmental concern. Yokogawa's submersion holder with an ultrasonic+air-jet cleaner (customized product) can reduce the manual cleaning frequency to just once every one or two months.

Continuous technology improvement is ongoing in the pulp & paper industry to obtain the best possible performance. Problems at the wet end (stock preparation) can rarely be corrected downstream. That is why monitoring and controlling pH in pulp stock is critical to the paper making process. Essentially, at every stage in the manufacture of paper, correct pH values play a vital role.

Reverse osmosis (RO) is a separation process that uses pressure to force a solution through a membrane that retains the solute on one side and allows the pure solvent to pass to the other side. More formally, it is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure.

Sour Water is the wastewater that is produced from atmospheric and vacuum crude columns at refineries. Hydrogen sulfide and ammonia are typical components in sour water that need to be removed before the water can be reused elsewhere in the plant.

Power plant boiler houses designed to burn coal or high sulfur oil are required by Federal and State pollution regulations to "scrub" (remove) sulfur dioxide from flue gasses to meet emission limits. SO₂ in flue gasses is known to be harmful to the environment, as it is one contributor to the formation of acid rain. pH control is critical for the proper functioning of the scrubber system.

For control of batch neutralization, a pH measurement coupled with a timer-controlled chemical feed scheme provides very satisfactory results.

This system can be adapted for either acid waste or alkaline waste neutralization.

Wet scrubbers are used in utilities, paper mills, and chemical plants to remove sulfur dioxide (SO₂) and other pollutants from gas streams. Undesirable pollutants are removed by contacting the gases with an aqueous solution or slurry containing a sorbent. The most common sorbents are lime, Ca(OH)₂, and limestone, CaCO₃. 

Wastes have been considered to be a serious worldwide environmental problem in recent years. Because of increasing pollution, these wastes should be treated. However, industrial wastes can contain a number of valuable organic components. Recovery of these components is important economically. Using conventional distillation techniques, the separation of acetic acid and water is both impractical and uneconomical, because it often requires large number of trays and a high reflux ratio. In practice special techniques are used depending on the concentration of acetic acid. 

In flue gas desulfurization systems that use magnesium hydroxide (Mg(OH)₂) slurry, the consumption of the desulfurization agent (Mg(OH)₂) is controlled by using online pH analyzers. A great concern in the pH measurement is heavy staining of the pH electrodes by the Mg(OH)₂ slurry. To ensure accurate measurement, frequent cleaning of the electrodes with an acid is required, adding to both maintenance workload and cost.

Industry:Chemical, Power

In stable dispersion of fine particles is the pre-requisite for the selective flocculation technique involving separation of ultra-fine valuable particles from the gangue. Among mineral processing techniques selective flocculation technique is known to have outstanding potential of capturing the particles of particular mineral in slurry of mixed mineral system by selective adsorption of water soluble polymers known as flocculants.

Maximize steel plant efficiency with comprehensive waste treatment solutions. From coal washer to blast furnace waste, optimize processes for quality.

Where and why are the pH Measurements important in a brewery? No one wants a skunky beer. pH measurements in the wort, during mashing/souring the malt, and in the yeast enzymes are critical.
 

After extraction from sugar cane or sugar beets, the juice must be purified to remove the many other organics and minerals that accompany it. The processing to accomplish this is heavily dependent on reliable pH measurement and control as illustrated. 

The quality of paper for printing or writing should be high and it depends on many parameters. Cobb is one of the parameters, which requires control. Using a retractable fitting, this optimum pH level can be achieved by using Yokogawa's 4-wire pH Analyzer with a suitable, retractable fitting and sensor. Since a separate controller is not required for the dosing pump, this solution provides a cost-saving.
 

Wastewater from electroplating facilities and certain types of chemical plants contains toxic forms of hexavalent chromium such as chromate and dichromate. The hexavalent chromium in this wastewater must be reduced before the water can be discharged. This requires a two-step process: hexavalent chromium (CR₆) is reduced to trivalent chromium (CR₃); and CR₃ is precipitated as chromium hydroxide.

Industry:Electrical and Electronics

Yokogawa’s Process Liquid Analyzers series help pigment producers achieve a more reliable and accurate analysis of pH during industrial bioprocesses, improving product quality with less total operation costs.

Fish are totally dependent upon water to breathe, feed, grow, maintain a salt balance, and reproduce. Water quality determines the success or failure of an aquaculture operation.

In the manufacturing of Glass-Fiber wool for insulation a melt of a material such as glass is inductively heated at a stage intermediate an initial liquefying stage and a refining stage. Induction heating is the process of heating an electrically conducting object (usually a metal) by electromagnetic induction, where eddy currents are generated within the metal and resistance leads to Joule heating of the metal.

The level of dissolved oxygen is critical to the quality and consistency of any brew. Too little dissolved oxygen results in the fermentation step of the process will lead to: off flavors (e.g. poor removal of diacetyl and acetaldehyde), poor yeast crop in terms of quantity and vitality, and low ester and alcohol production. 

The detectors used to perform dissolved oxygen (DO) measurement in oxidation ditch type sewage treatment plants tend to become dirty quickly and require frequent cleaning. It has been d ifficult to remedy this problem inexpensively. One solution that significantly reduces the sensor maintenance workload is the use of float holders.

Many Ethanol plants running today are using a combination style pH electrode with a non-flowing reference to measure pH in the Mash Slurry transfer line from the Mash slurry mix tank to cook. The Mash is being pumped out of the Mash Slurry tank is at approximately 180 °F and 40 to 60 psig.

Yokogawa’s conductivity transmitters and converters possess USP functions that make this seemingly complex and troublesome requirement pain-free and automatic.

Optimizing four key factors will decrease pH sensor costs and optimize process control and overall plant efficiency.

The accuracy of pH measurements depends upon maintenance; maintenance frequency largely depends upon the application. Understanding and addressing the causes of pH measurement difficulties comprise key to ensuring stable and accurate readings.

The lifetime of a pH sensor has a significant impact on the overall annual costs of a pH measuring loop. Optimizing four key factors will decrease these costs and optimize process control and overall plant efficiency.

Kind of. Calibration itself will not extend the life of a sensor, however, a sensor that is not calibrated properly can cause unreliable measurements - that are often misdiagnosed leading to unnecessary replacements.

Optimizing the maintenance cycle is not always straightforward. In some cases, cleaning once a week is sufficient and other processes may require every 8 hours.

Learning these four lessons will help you improve your engineering skills and most importantly extend the life of your pH sensors.

Select the correct pH glass and reference type to improve your pH sensor lifetime and you can limit or even eliminate the effects of temperature and pressure on especially the reference sensor.

We invited Nick Crowe, our Product Manager for Analytical Products to debunk myths around Liquid Analysers. In part 1 of this series, Sean asked him whether the maintenance-free analyzer is a myth?

This video aims to answer the following: How does a traditional pH reference work and what are it's common problems? How does a sodium pH reference work and what are it's benefits? This webinar was presented February 12th, 2013.

Watch this on-demand webinar to review and learn the theory behind pH measurement, the issues surrounding high purity pH measurements, and how to implement good calibration and maintenance procedures.

What about other instrumentation pain-points in the blow tank, washing, or bleaching process?

In the digester process, high temperature and pressure, along with the slurry pulp, can cause extreme damage to traditional meters.